document_title: List of oldest church buildings

question_text: where was the first catholic church built in the world

text: List of oldest church buildings

text: Early Christianity[edit]

text: Church buildings of the 2nd to 4th centuries, either excavated archaeologically or substantially preserved.

text: Africa[edit]

text:
hideBuilding

Image

Location

Country

Oldest Part

Denomination

Notes

Monastery of Saint Anthony

Eastern Desert

Egypt

356

Coptic Orthodox

Partially destroyed in the 11th century and rebuilt; very little of the original structure remains.

Monastery of Paromeos

Wadi El Natrun

Egypt

335

Coptic Orthodox

Built by St. Macarius the Great, its name(Pa-Romeos) which in Coptic means "The Romans" is thought to refer to his two Roman disciples Saints Maximus and Domitius sons of the Roman Emperor Valentinian II. The Monastery flourished during the Middle Ages and continues to be a major monastery within Egypt.

Monastery of Saint Macarius the Great

Wadi El Natrun

Egypt

360

Coptic Orthodox

Built by St. Macarius the Great, Who was a father for more than 4000 Monks of different Nationalities. It has been continually inhabited since its construction and has experienced renovation and expansion in the 20th century.

Monastery of Saint Pishoy

Wadi El Natrun

Egypt

4th Century

Coptic Orthodox

Built by St Pishoy, his body was moved to the monastery on December 13 in 841 AD. The Monastery contains five Churches and a Keep, constructed in the 5th century AD, for protection against Berber raids. The Monastery has been raided several times by the Berbers throughout the ages, the most famous incident is when forty of the Monasteries elders were martyred and thrown in a neighboring well, consequently called "The Well of Martyrs".

Monastery of St. Mary Deipara

Wadi El Natrun

Egypt

4th Century

Coptic Orthodox

Most commonly known as"Syrian Monastery". Some sources claim that Monks had lived there since the 4th century, but it is most commonly believed that it Was established in the 6th century by monks from the Monastery of St. Pishoy who rejected the Julian Heresy, which claimed that Christ was incorruptible.  As a result, they abandoned the Monastery and established a new one which they named after the Theotokos, to emphasize that they believed in Christ's humanity and corruptibility. The Monastery was bought by Syrian Merchants in the eighth century and inhabited by Syrian Monks.

Abu Mina Basilica and Complex

Alexandria

Egypt

late 3rd century

Coptic Orthodox

Built near the place at which the Body of St. Mina the Martyr was buried, the Basilica was ordered to be built by Emperor Zenon after the Saint healed his leper daughter. A Monastic community and a city eventually sprang up near the Basilica and it became a famous site of pilgrimage. Terracotta pots with the image of the Saint and spices from his body have been found all throughout the Roman Empire and as far north as Germany. The City complex and Basilica as well as the Monastery were sacked and destroyed in the 7th century by the Arab invaders. The ruins are currently a UNESCO World Heritage site.

Monastery of St. John the Short

Wadi El Natrun

Egypt

4th century

Coptic Orthodox

Built by Saint John around his "Tree of Obedience". The Monastery remained open until the 17th century when it was finally abandoned. Originally the body of St. John was in a Church near modern-day Suez, Egypt, but his disciples moved it to the monastery in 515 AD.

Monastery of St.Moses the Strong

Wadi El Natrun

Egypt

4th century

Coptic Orthodox

Built by Saint Moses the Strong, who is called the Apostle of Peace. St. Moses was an Outlaw who repented and became a Monk in Sketes. As he progressed in age he became a father unto many, some of whom were criminals following his example. He was ordained a Priest and built a Chapel and a small monastic community around it. In 405 AD St. Moses heard news that the Monastery was going to be sacked, his disciples wanted to pick up arms and defend their home, however he urged them to either stand as Martyrs with him or escape to neighboring monastic communities. He and 7 others remained in the Church as it was sacked. Later some of his disciples returned and took his body, and the 7 others, with them to Paramous, where they lay today. The Monastery has remained desolate to this day.

Church of Our Lady Mary of Zion

Axum

Ethiopia

4th century

Ethiopian Orthodox

Originally built in the 4th century, it has been rebuilt several times, most recently in the 17th century during the reign of Emperor Fasilides.

text: Asia[edit]

text:
hideBuilding

Image

Location

Country

Oldest Part

Denomination

Notes

Dura-Europos church

Dura-Europos

Syria

c. 241[2]

Early Church

House church. Several walls still standing, oldest images of Jesus discovered within the surviving frescoes of the large baptistry room. Fragments of parchment scrolls with Hebrew texts unearthed containing Christian Eucharistic prayers closely connected with the prayers in the Didache.[10]

Megiddo church

Legio near Tel Megiddo

Israel

late 3rd century[11]

Early Church

Ruins discovered on prison grounds in 2005, possibly oldest building constructed as a church ever discovered.  It retains mosaic floor decoration with Christian motifs – possibly the oldest building with this feature.[12]

Aqaba Church

Aqaba

Jordan

late 3rd-early 4th century[3]

Early Church

Ruins uncovered in 1988; Remains of an early basilica.[13] Considered to be the world's first purpose-built church.[14]

Etchmiadzin Cathedral

Vagharshapat

Armenia

301 (tradition); current church: 483-484

Armenian Apostolic Church

According to scholars it was the first cathedral of the world (but not the first church) built in ancient Armenia.

Mar Sarkis Monastery

Ma'loula

Syria

4th century

Syriac Catholic

Built in the 5th century on the remains of a pagan temple, it likely predates the Council of Nicea (325 AD) as evidenced by the fact that it has a round altar, which was prohibited at the Council.[15] The monastery suffered extensive damage and desecration in the Syrian Civil War.[16]

Sts. Constantine & Helena Cathedral

Yabroud

Syria

326

Syriac Catholic

Originally built as a pagan temple dedicated to Baalshamin during the first millennium BC, it was converted to a church when St. Helen passed through the city on her way back to Rome from Jerusalem. The church was damaged during the Syrian Civil War.[17]

Church of the Holy Sepulchre

Jerusalem

335

Simultaneum

Originally completed in 335, the building suffered extensive damage and was almost completely destroyed in 1009. The church was rebuilt in 1038.

Church of the Nativity

Bethlehem

Palestine

339

Simultaneum

It was commissioned in 327 by Constantine and his mother Helena over the site that was traditionally considered to be located over the cave that marks the birthplace of Jesus. The original basilica was completed in 339.

Mar Mattai monastery

Mount Alfaf

Iraq

363

Syriac Orthodox

Extensively rebuilt over the years with the earliest portions built during the 4th century.

Kasagh Basilica

Aparan

Armenia

4th or 5th century

Armenian Apostolic

Original building retains many ancient features.

Mor Gabriel Monastery

Midyat

Turkey

397

Syriac Orthodox

Built on the ruins of an old Assyrian temple, the property is now currently subject to a dispute between the Turkish government and the church.

Chora Church

Istanbul

Turkey

4th century

Eastern Orthodox

Very little remains of the 4th-century structure, but it contains impressive 13th-century mosaic decoration.  It was converted to a mosque in 1501 and has been a museum since the time of Ataturk.[18]

Hagia Irene

Istanbul

Turkey

4th century

Eastern Orthodox

Now a museum and concert hall (due to its excellent acoustics).  Its excellent state of preservation is due to the fact that it lies inside the Ottoman palace complex (Topkapı Palace).[19]

Jubail Church

Al-Jubail

Saudi Arabia

4th century

Assyrian Church

The government hides it from locals and bans foreigners from openly visiting it – even archaeologists.[20]

Church of St Peter

Antioch (Antakya)

Turkey

4th or 5th century

Syriac Orthodox

Cave church used by very first Christians of Antioch, where St. Peter presided as bishop. Known by its original Aramaic name of Knisset Mar Semaan Kefa. Extensively reconstructed, with oldest surviving elements from 4th or 5th century.[21]

text: Europe[edit]

text:
hideBuilding

Image

Location

Country

Oldest Part

Denomination

Notes

Cathedral of Saint Domnius

Split

Croatia

295–305

Roman Catholic

Built 295–305 as the Mausoleum of emperor Diocletian, is the second oldest structure used by any Christian Cathedral. Consecrated in 641 AD, is regarded as the oldest Catholic cathedral in the world that remains in use in its original structure, without near-complete renovation at a later date.

Rotunda of St. George

Thessaloniki

Greece

306

Greek Orthodox

Built as an imperial mausoleum or temple, currently a museum, with church access for various festivities.  Largely as built in 305; consecrated later in the century.

Santi Cosma e Damiano

Rome

Italy

c. 309

Roman Catholic

Occupies the former space of the Temple of Romulus in the Roman Forum.

Panagia Ekatontapiliani

Parikia

Greece

326

Greek Orthodox

Panagia Ekatontapyliani (also known as the Church of 100 Doors) is a historic Byzantine church complex.

Stavrovouni Monastery

Larnaca

Cyprus

327–329[22]

Greek Orthodox

It was founded by Saint Helena the mother of the Byzantine Emperor Constantine the Great at the place where after a miracle she found the lost Holy Cross on her way back from her pilgrimage to the Holy Land. Saint Helena went on the pilgrimage after the First Ecumenical Synod in Nicaea (325). The monastery has a piece of the Holy Cross left there by Saint Helena.

St. Peter's Basilica

Vatican City

Vatican City State

333

Roman Catholic

Largest church in the world and the seat of Roman Catholicism, the current church (1635) is built on the site of the original basilica and the grave of St. Peter (who was martyred in Rome).[23]  The actual grave is visible in excavations under the church.  The original floor and columns are visible in a space under the 17th-century floor.

Santa Maria in Trastevere

Rome

Italy

340

Roman Catholic

The first sanctuary was built in 221 and 227 by Pope Callixtus I and later completed by Julius I, but the oldest parts of the present church, the wall structure and floors, date from 340 AD[24][25]

Cathedral of Trier

Trier

Germany

340

Roman Catholic

Oldest cathedral in Germany, and still in use today.  Its construction was overseen by Bishop Maximin of Trier, the construction of the grandest ensemble of ecclesiastical structures in the West outside Rome. A few 4th-century elements remain in a mainly Romanesque building.

Basilica di San Lorenzo

Milan

Italy

364

Roman Catholic

When built, it was the biggest circular church building standing. It was an inspiration for the Hagia Sofia in Constantinople.  Few ancient features remain.

Basilica di San Simpliciano

Milan

Italy

c. 374

Roman Catholic

Exterior walls are original from the late 4th century. Roman basilica windows as in Cathedral of Trier are still visible on the flanks of the basilica.

Basilica of Saint-Pierre-aux-Nonnains

Metz

France

380

Roman Catholic

Originally built to be part of a Roman spa complex, the structure was converted into use as a church in the 7th century when it became the chapel of a Benedictine monastery. It is the oldest church building in France.

San Nazaro in Brolo

Milan

Italy

c. 382

Roman Catholic

One of the earliest Latin cross buildings in western Europe; retains few ancient features.[26]

San Paolo fuori le mura

Rome

Italy

386

Roman Catholic

One of the four major Constantinian basilicas in Rome, and the only one to retain its antique character, the basilica was heavily damaged by an 1823 fire.  It was rebuilt true to form, however, so it remains one of the best "preserved" Constantinian basilicas in the Roman world.  All that remain of the ancient basilica are the interior portions of the apse and the triumphal arch.[27]

Santi Giovanni e Paolo

Rome

Italy

398

Roman Catholic

A 4th-century basilica was erected on the site of one of the most well-preserved "house churches" of early Christianity (dating from the 1st, 2nd or 3rd century), with intact fresco decoration.[28]  The houses are part of a museum currently, but the basilica still functions as a church.

Lullingstone Roman Villa

Eynsford, Kent

England

4th century

Early Christian

Room in a large Roman villa turned into a Christian chapel or house church, with wall-paintings surviving (Chi-Rho, largely restored, illustrated)

Basilica di Sant'Eustorgio ruins

Milan

Italy

c. 4th century

Roman Catholic

Some ruins remain of the apse of the ancient basilica.

Church of St. George

Sofia

Bulgaria

4th century

Bulgarian Orthodox

Built by the Romans with many later additions, St. George is the oldest building in Sofia and the only one dating from the Roman era.  Still a functioning church.[29]

Aula Palatina (Konstantinbasilika)

Trier

Germany

4th century

Evangelical Church in the Rhineland

A Roman palace basilica that was built by the Emperor Constantine at the beginning of the 4th century. The basilica contains the largest extant hall from antiquity. The church was converted to Protestant use from its original Roman Catholic use in 1856.[30]

Santi Nereo e Achilleo

Rome

Italy

4th century

Roman Catholic

Adjoins the Baths of Caracalla at the site where St. Peter is said to have dropped the cloth covering his wounds upon his removal from the Mamertine Prison.  First referenced in 336, a 15th-century basilica sits on its original site; only the columns are original.[31]

Santa Pudenziana

Rome

Italy

4th century

Roman Catholic

Retains original and unique late Roman mosaic decoration.[32]

San Clemente al Laterano

Rome

Italy

4th century

Roman Catholic

The present basilica was built just before the year 1100, but beneath it is an intact 4th-century basilica that had been converted out of the home of a Roman nobleman, part of which had in the 1st century briefly served as an early church.  This ancient basilica retains fresco decoration (see image).  The basement the house had in the 2nd century briefly served as a mithraeum.  The home of the Roman nobleman had been built on the foundations of a republican era building that had been destroyed in the Great Fire of Rome in 64 AD.

Santa Costanza

Rome

Italy

4th century

Roman Catholic

Built under Constantine as a mausoleum for his daughter, Costanza.  Retains many original mosaic decorations, and her porphyry sarcophagus is a gem of the Vatican Museum.

Santi Quattro Coronati

Rome

Italy

4th century

Roman Catholic

Sanctuary is located in an isolated green area of Rome, so it retains the ambience of the area in antiquity.

text: Valkum (Fenekpuszta) Built before 433 AD remains of a Bazilika in Hungary near lake Balaton

text: Late Antiquity and Early Middle Ages[edit]

text: Church buildings dating to between the 5th and 10th centuries.

text: Africa[edit]

text:
hideBuilding

Image

Location

Country

Oldest Part

Denomination

Notes

Saint Catherine's Monastery

Sinai Peninsula

Egypt

548 AD

Greek Orthodox

Built by Emperor Justinian surrounding St. Helen's Chapel of the Burning Bush. One of the Monasteries was converted into a Mosque by the Fatimid Caliphs in the 10th century and remained in popular use till the 13th century. The Mosque was restored in the 20th century and continues to be used in special occasions.

Church of the Virgin Mary in Haret Zuweila

Cairo

Egypt

10th Century AD

Coptic Orthodox

Served as the See of St. Mark, and the Seat of the Coptic Orthodox Pope of Alexandria from 1400 to 1520. Later a Nun's Convent was added to it in the 19th Century.

Monastery of Saint Paul the Anchorite

Eastern Desert

Egypt

560 AD

Coptic Orthodox

Partially destroyed in the 15th century and rebuilt; was abandoned in the 16th century, but was later repopulated by Monks from St. Antony's monastery early in the 17th century.

Church of Saint Menas

Cairo

Egypt

6th century AD

Coptic Orthodox

Built in honor of the Saint and Martyr, the Church was built within what later was renamed "Cairo". The Church was renovated in the 8th century, and the body of Saint Mena which had been in the ruins of the Abu Mena Complex in Mariout was moved there. The body remained there until a modern Monastery bearing the Saint's name was built adjacent to the ruins, in 1967 the body was moved to the new Monastery. The Church remains open to this day and is a prominent pilgrimage and tourist center in Cairo.

Debre Damo

Tigray Region

Ethiopia

6th century

Ethiopian Orthodox

The best preserved example of Aksumite Architecture.

text: Asia[edit]

text:
hideBuilding

Image

Location

Country

Oldest Part

Denomination

Notes

Monastery of Stoudios

Istanbul

Turkey

462

Greek Orthodox

No longer a functioning church, and was a mosque until it fell into ruin.  As with many other archaeological sites in Turkey, plans to revert the ruins back into a mosque are underway.[33]

Qalb Loze

Qalb Loze

Syria

5th century

Assyrian Church

Built in 460s, one of the best-preserved early Syrian churches, the first known with a wide basilica, where the columns that separate the aisles from the nave have been replaced with low piers and soaring arches that create the feeling of expanded space.

Church of Saint Simeon Stylites (Deir Semaan)

Aleppo

Syria

475

Greek Orthodox

Once a popular pilgrimage site, now in ruins, but walls still standing.

Bolnisi Sioni

Bolnisi

Georgia

479–493

Georgian Orthodox

The oldest extant church building in Georgia.

Turmanin Basilica

Turmanin

Syria

480

Early Church

Drawing reconstruction shown. Now in ruins, served a monastery and hospice.[34]

Etchmiadzin Cathedral

Vagharshapat

Armenia

483

Armenian Apostolic

Built in 483 and heavily rebuilt in the following centuries. Still the main cathedral of the Armenian Apostolic Church. A UNESCO World Heritage Site.

Mor Hananyo Monastery

Mardin

Turkey

493

Syriac Orthodox

Founded in 493 by Mor Shlemon on the site of a temple dedicated to the Assyrian sun god Shamash that was converted into a citadel by the Romans, then transformed into a monastery. Better known as Saffron Monastery. (Deir-ul-Zafran)

Dranda Cathedral

Dranda

Abkhazia/Georgia

c. 550–600

Georgian Orthodox

The oldest church building in Abkhazia, still functioning as a church.

Church of the Nativity

Bethlehem

West Bank

c. 565

Simultaneum

One of the oldest church buildings in the world which has continuously functioned as a church.

Jvari (monastery)

Mtskheta

Georgia

590–604

Georgian Orthodox

A World Heritage Site.

text: Europe[edit]

text:
hideBuilding

Image

Location

Country

Oldest Part

Denomination

Notes

San Vitale

Rome

Italy

400

Roman Catholic

Although it was restored several times, the church retains its original structure and walls; it actually sits below street level due to its age and relative lack of major structural renovations.  The portico is one of the most ancient parts of the church.

Santa Sabina

Rome

Italy

422

Roman Catholic

Mostly unaltered, with some original mosaic decoration and agate window treatments.  Notably, wooden doors date from around the same era and contain an early depiction of the crucifixion.

San Giovanni Evangelista

Ravenna

Italy

424

Roman Catholic

Partially original walls, with original floors and columns under layers of new floors.

Santa Maria Maggiore

Rome

Italy

432

Roman Catholic

Features intact original mosaic decoration, including some of the oldest depictions of the Virgin Mary.  18th-century façade covers 12th-century façade which replaced the original.

Church of the Acheiropoietos

Thessaloniki

Greece

450–470

Greek Orthodox

The Acheiropoietos has been dated from its bricks and mosaics to c. 450–470, making it perhaps the earliest of the city's surviving churches. It was modified in the 7th century and again in the 14th and 15th centuries, but retains much of its original character. Known as the Panagia Theotokos in Byzantine times, it is dedicated to Mary.

Santo Stefano Rotondo

Rome

Italy

455

Roman Catholic

Believed to be the first church in Rome with a circular plan, inspired by the Church of the Holy Sepulchre in Jerusalem.

Sant'Agata dei Goti

Rome

Italy

460

Roman Catholic

Built for the Arian Goths by Ricimer, this ancient church retains its original site plan and columns, despite many restorations.

Stenče Basilica

Polog Valley

Macedonia

420–465

Early Church

To date remains of 16 early Christian basilicas have been revealed in the Polog Valley, of which 12 in Tetovo area and 4 in Gostivar area, and best has been investigated the one in Stenče dating from the 5th century AD, which is unique in Macedonia with 3 baptisteries.

Santa Prisca

Rome

Italy

4th or 5th century

Roman Catholic

In the interior, the columns are the only visible remains of the ancient church after a 17th-century restoration, but the floor plan remains. A baptismal font allegedly used by Saint Peter is also conserved.

Little Hagia Sophia

Istanbul

Turkey

527

Greek Orthodox

A former Eastern Orthodox church dedicated to Saints Sergius and Bacchus in Constantinople, converted into a mosque during the Ottoman Empire.  This Byzantine building with a central dome plan was erected in the 6th century by Justinian, likely was a model for Hagia Sophia, and is one of the most important early Byzantine buildings in Istanbul.  Poorly executed restorations leave the church with a modern character.[35]

Hagia Sophia

Istanbul

Turkey

532–537

Greek Orthodox

For almost 1,000 years it was the largest church in Christendom, the main center of worship for the Eastern Orthodox Church, and the jewel of Constantinople.  In 1453, it was captured and converted into a mosque, becoming a museum in 1932 under Atatürk.

Basilica di San Vitale

Ravenna

Italy

547

Roman Catholic

The best-preserved basilica from the time of Justinian I, filled with outstanding Byzantine mosaics in an excellent state of preservation.

Basilica of Saint Servatius

Maastricht

Netherlands

c. 550

Roman Catholic

The oldest church in the Netherlands.  There was a small memorial chapel on the site dedicated to the Saint Servatius (310–384),  who became the first bishop of Maastricht, and this was later replaced by a larger stone church, incorporating the ancient stone.

Dormition of the Theotokos Church, Labovë e Kryqit

Gjirokastër

Albania

6th century

Eastern Orthodox

The Dormition of the Theotokos Church (Albanian: Kisha e Shën Mërisë) is a church in Labovë e Kryqit, Gjirokastër County, Albania. The foundation on the structure dates from 6th, with the rest from 13th. It is a Cultural Monument of Albania.[36] The present building dates from the 13th century.[37]

St. Martin's Church

Canterbury

United Kingdom

597

Anglican

The oldest church building in England, still functioning as a church.

Church of Saint Apostles Peter and Paul

Stari Ras, Novi Pazar

Serbia

6th century

Serbian Orthodox

Also known as Peter's Church (Serbian: Петрова црква / Petrova crkva), it is a Serbian Orthodox church, the oldest intact church in Serbia.  It is situated on a hill of Ras, the medieval capital of the Serbian Grand Principality (Rascia), near Novi Pazar, Serbia. It is part of the Stari Ras complex, listed on the UNESCO List of World Heritage Sites in Serbia.  The foundations of the structure date from the 6th century, with the rest from the 7th, 9th, and 12th centuries.[38]

Saint Sofia Church

Sofia

Bulgaria

6th century

Bulgarian Orthodox

The church was built near the Amphitheatre of Serdica. 343 in the building took place the Council of Serdica that was attended by 316 bishops. The current building is from the 6th century

Chapel of São Frutuoso

Real, Braga

Portugal

656

Catholic Church

Visigoth chapel. It has been modified and rebuilt many times.

San Juan Bautista

Baños de Cerrato, Venta de Baños, Castile and León

Spain

Completed in 661

Catholic Church

Visigoth church built by King Recceswinth in 661 and whose solemn ceremony of consecration is believed to have been on January 3, 661. The excavations carried out in the years 1956 and 1963 found a medieval necropolis of 58 tombs to the northwest of the church and also found three pieces of bronze of the 7th century: 2 lychee-shaped belt clasps and 1 liturgical object.

Santa María de Melque

San Martín de Montalbán, Castile-La Mancha

Spain

668

Catholic Church

It served as a monastic ensemble of the Visigoths. The radiocarbon dating of a sample obtained from the conserved part of the original stucco plaster has given a most probable construction date in the interval 668-729 AD. Probably its construction was paralyzed when the arrival of the Arabs began and it was finished and it was reformed later, having suffered multiple historical vicissitudes.

Chapel of St Peter-on-the-Wall

Bradwell-on-Sea, Essex

England

660–662

Catholic, now Church of England

Early Anglo-Saxon church, reusing Roman brick. Still in use.[39]

Escomb Church

Escomb, County Durham

England

c. 670-675

Catholic, now Church of England

Early Anglo-Saxon church. Still in use.[40]

All Saints' Church, Brixworth

Brixworth, Northamptonshire

England

before 675

Catholic, now Church of England

Early Anglo-Saxon church, with later additions. Still in use.[41]

San Pedro de la Nave

El Campillo, San Pedro de la Nave-Almendra, Castile and León

Spain

680

Catholic Church

Visigothic church. It must have been built between 680 and 711.

Crypt of San Antolín of the Cathedral of Palencia

Palencia, Castile and León

Spain

7th century

Catholic Church

Located under the current cathedral of Palencia. It is the only remnant of the primitive Visigothic cathedral built in the second half of the 7th century. The oldest vestige of worship that is preserved today is the bottom of the crypt, a building dating from the middle of the 7th century. The remains of Antolín, noble Gallo-Visigoth, saint and martyr, would have arrived in Spain in the procession of King Wamba from Narbonne in the year 673. Wamba himself would order the construction of the burial.

Hermitage of Santa María de Lara

Quintanilla de las Viñas, Mambrillas de Lara, Castile and León

Spain

Completed at late-7th century or early-8th century

Catholic Church

Visigothic hermitage.

Church of St John the Baptist, Kerch

Kerch

Ukraine

717

Ukrainian Orthodox

Founded in 717, later rebuilt on several occasions.

Santa Cruz de Cangas de Onís

Cangas de Onís, Asturias

Spain

Completed in 737

Roman Catholic

Church of Kingdom of Asturias. t was consecrated in 737. The church was restored in 1633 and 1936. Now it is a World Heritage Site.

Church of San Juan Apóstol y Evangelista

Santianes, Pravia, Asturias

Spain

774

Roman Catholic

Church of Kingdom of Asturias. Built between 774 and 783. In the church the debate between the Beatus of Liébana and Elipando of Toledo was celebrated, on the adoptionist interpretation of the divinity of Christ. Now it is a World Heritage Site.

Oviedo Cathedral

Oviedo, Asturias

Spain

781

Roman Catholic

Church of Kingdom of Asturias. It underwent modifications and was enlarged until 16th century. Now it is a World Heritage Site.

Santa María de Bendones

Bendones, Asturias

Spain

792

Roman Catholic

Church of Kingdom of Asturias. Built between 792 and 842. It suffered a restoration after Spanish Civil War. Now it is a World Heritage Site.

Aachen Cathedral

Aachen

Germany

805

Roman Catholic

It is the oldest cathedral in northern Europe and was constructed by order of the emperor Charlemagne, who was buried there after his death in 814.

San Julián de los Prados

Oviedo, Asturias

Spain

Completed in 830

Roman Catholic

Church of Kingdom of Asturias. The church's construction was ordered by Alfonso II of Asturias and it was built by the court architect Tioda. Now it is a World Heritage Site.

Santa María del Naranco

Municipality of Oviedo, Asturias

Spain

Completed in 842

Roman Catholic

Church of Kingdom of Asturias. Built as a banqueting house, later used as a church. It is a World Heritage Site.

San Miguel de Lillo

Oviedo, Asturias

Spain

Completed in 842

Roman Catholic

Church of Kingdom of Asturias. It is a World Heritage Site.

Santa Cristina de Lena

Lena, Asturias

Spain

Completed in 852

Roman Catholic

Church of Kingdom of Asturias. It is a World Heritage Site.

Iglesia de San Tirso

Oviedo, Asturias

Spain

9th century

Roman Catholic

Church of Kingdom of Asturias. It was founded in the 9th century. It has undergone various reconstructions and restorations. Now it is a World Heritage Site.

San Pedro de Nora

Las Regueras, Asturias

Spain

9th century

Roman Catholic

Church of Kingdom of Asturias. It suffered a restoration after Spanish Civil War.

Cámara Santa

Oviedo, Asturias

Spain

9th century

Roman Catholic

Church of Kingdom of Asturias. Its function, practically from its construction and that it conserves at present, has been the one of guard of the relics and cathedral treasure. It is now a World Heritage Site.

San Salvador de Valdediós

Municipality of Villaviciosa, Asturias

Spain

9th century

Roman Catholic

Church of Kingdom of Asturias. Consecrated in 893. Now it is a World Heritage Site.

Santiago de Gobiendes

Gobiendes, Asturias

Spain

late-9th century

Roman Catholic

Church of Kingdom of Asturias. It was restored in three times.

Santo Adriano de Tuñón

Tuñón, Asturias

Spain

9th century

Roman Catholic

Church of Kingdom of Asturias. Founded in 891. It suffered many reforms.

Church of St. Margaret of Antioch

Kopčany

Slovakia

9th or 10th century

Roman Catholic

The only remaining Great Moravian building. The oldest church in Slovakia. Well-preserved and openly accessible to the public.

Church of San Salvador de Priesca

Villaviciosa, Asturias

Spain

Completed in 921

Roman Catholic

Church of Kingdom of Asturias. Consecrated in 921. It suffered some enlargements and two restorations. Now it is a World Heritage Site.

San Pietro in Trento

Ravenna

Italy

c. 977

Roman Catholic

Facade restored, but very much intact.  Constructed by Galla Placidia.

text:
The Dead Cities of Syria feature ruins of many churches, all abandoned prior to the 8th century and many dating from the 4th and 5th centuries
St. George's Church, Rihab, Jordan, 1st to 8th centuries. Dates are contested by experts but area under the church may have been used for Christian worship as early as 33 AD[42][43][44]
Church of Sts. Constantine and Helen, Yabroud, Syria, 5th century,[45] Built from Roman temple; Desecrated in 2014 by extremists in Syrian Civil War[46][17]
Al-Aqiser church, built in 500s, oldest church building in Iraq (foundations, some walls remain).[47]
Saint Elijah's Monastery, near Mosul, Iraq is a 6th-century ruin and among the oldest monasteries in Iraq
St. George's Church, Izra, Syria, Built in the 6th century[48][49]
Saint Hripsime Church, built 618 AD in Armenia (Armenian Apostolic)[citation needed]
The Hanging Church, Built c. 690 on site of earlier church, possibly the oldest church building in Egypt  (Coptic Orthodox)
Ateni Sioni Church, early 7th century, Georgia
Anchiskhati Basilica, built in the 600s, the oldest church building in Tbilisi.
São Pedro de Balsemão, built in the 7th century, possibly oldest church building in Portugal (Roman Catholic).
Densuş Church, built in 600s, oldest church building in Romania
St Peter's Church, Monkwearmouth, UK, porch and west wall date from 674 AD
St Paul's Church, Jarrow, UK, parts – including the original dedication stone – date from 685 AD
St Peter’s Church, Titchfield, Hampshire, UK,  some parts remain from c. 680
Great Church, Elst, Netherlands, church built in the 15th century, built upon and using the remains of two Gallo-Roman temples.
Gallarus Oratory, built between the 6th and 9th centuries, Possibly the oldest church building in Ireland
Church of Holy Cross, Nin, built in the 9th century, oldest church building in Croatia (Roman Catholic)[citation needed]
Kadamattom Church, India, built in the 9th century.[citation needed]
St. Mary's Forane Church, Kaduthuruthy, India, built in 500 AD. Also known as Kaduthuruthy Valiya Palli[50]
Church of Ayios Lazaros, Larnaca, built in the 9th century, one of the oldest churches in Cyprus[citation needed]
Church of SS. Peter and Paul, built at Budeč fortified settlement between 895 and 905 during rule of Spytihněv I is the oldest extant church building in the Czech Republic. The site (cf. cs:Budeč (hradiště)) is located near village of Zákolany, about 17 kilometres (11 mi) NW of Prague.
Tkhaba-Yerdy Church, Russia, built prior to the 9th century
Greensted Church, UK, built in the mid-9th or mid-11th century, oldest wooden church building in Europe
Worth Church, UK, dated c. 950 to 1050 AD.[51]
Shoana Church, Russia, built c. the 10th century
Senty Church, Russia, built c. the 10th century
Church of Tarnaszentmária, built at the end of the 10th century
The Pantheon in Rome became a church in AD 608.

text: High to Late Middle Ages[edit]

text: A selection of notable, extant 11th- to 14th-century churches.

text:
Building

Image

Location

Country

Oldest Part

Denomination

Notes

Church of Our Lady

Aarhus

Denmark

1060

Lutheran

An older wooden church was on the site in the 10th century. The crypt of the church is the oldest extant stone church in Scandinavia.  It is still functioning as a church.

Cathedral of Pisa

Pisa

Italy

1063

Roman Catholic

Built on the foundations of an older church. Dedicated to the Assumption of St. Mary, it is a Primatial church.

Santiago de Compostela Cathedral

Santiago de Compostela, Galicia

Spain

1075 (current church)

Roman Catholic

According to tradition, the Apostle James, son of Zebedee spread Christianity in the Iberian Peninsula. In the year 44 he was beheaded in Jerusalem and his remains were later transferred to Galicia in a stone boat. The king Alfonso II of Asturias ordered the construction of a chapel in 810s in the place. This chapel was followed by a first church in 829 and later by a pre-Romanesque church on 899, gradually becoming an important place of pilgrimage. In 997 this primitive church was reduced to ashes by Almanzor, commander of the army of the Caliphate of Cordoba. The construction of the current cathedral in the same place was built between 1075 and 1122 under the reign of Alfonso VI of León and Castile. The baroque façade of Obradoiro was made in 1740; also baroque is that of Acibecharía; that of Pratarías was built by Master Esteban in 1103; the Pórtico da Gloria, a primordial work of Romanesque sculpture, completed by Master Mateo in 1188.

St. Michael's Church

Vienna

Austria

1220–1240

Roman Catholic

One of the oldest churches in Vienna, Austria, and also one of its few remaining Romanesque buildings. Dedicated to the Archangel Michael, St. Michael's Church is located at Michaelerplatz across from St. Michael's Gate at the Hofburg Palace.

text:
Christ Church Cathedral, Dublin, Ireland, built c. 1030
St. Margaret's Chapel, built in the 11th century, possibly the oldest church building in Scotland
Saviour Cathedral (Chernihiv), Ukraine, built in the 1030s
Saint Sophia Cathedral (Kyiv), Ukraine, built in the 1030s
Saint Cyril's Monastery (Kyiv), Ukraine, founded in 1140
Arkhyz churches, Russia, 10th to 13th centuries
Novgorod Cathedral, Russia, built between 1045 and 1050
Old Aker Church (Norwegian: Gamle Aker kirke) is a medieval church located in Oslo. An active parish, the church is the oldest existing building in Oslo from 1080.[citation needed]
Church of the Holy Sepulchre, rebuilt in 1089, in Jerusalem is venerated as Golgotha (the Hill of Calvary), where Jesus was crucified, and is said also to contain the place where Jesus was buried (the Sepulchre) (some walls from earlier structure may exist), (Greek Orthodox, Roman Catholic, Armenian Apostolic Orthodox, Syrian Orthodox, Coptic Orthodox, and Ethiopian Orthodox)
Church of St. Adalbert, Kraków, Kraków, Poland, built in the 11th century, possibly the oldest church building in Poland
Saint Sophia Cathedral in Polotsk, Belarus, 18th-century building with an 11th-century apse
Abbey of Romainmôtier: a 5th-century church was rebuilt in the 7th century, and again between 990 and 1030. The church building remained mostly unchanged since the 11th century, and qualifies as one of the oldest romanesque buildings in Switzerland.
Lund Cathedral, built in 1123, Possibly the oldest church in Sweden (although part of Denmark in 1123) (Lutheran)
St. Mary's Cathedral, Limerick, Ireland, founded in 1168.
St. Peter's Church, Hamburg & St. Nicholas' Church, Hamburg, Hamburg, Germany, Building Started 1189 but were rebuilt several times due to fire & war but still stand in their original positions today.
St. Audoen's Church, Dublin, Ireland, founded in 1190.
St. Patrick's Cathedral, Dublin, Ireland, founded in 1191.
Church of Saint George, Lalibela, Ethiopia, Built in the 12th century, one of the oldest church buildings in Ethiopia (Ethiopian Orthodox Church)
Church of St. Panteleimon (Nerezi), built in the 12th century, One of the oldest church buildings in Macedonia
Kalozha Church, the oldest extant church building in Belarus, 12th century.
Church of Kish, the oldest extant Armenian church building in Azerbaijan, 12th or 13th century.
Basilica of Saint Servatius, church congregation dating to 384 AD, current building built from 11th to 13th centuries, oldest congregation and possibly the oldest church building in the Netherlands (Roman Catholic)
Thiruvithamcode Arappally (Arappally means Royal Church) Kanyakumari District is the oldest Church building that still exists in India.[year needed][citation needed]
St. Canice's Cathedral, Kilkenny, Ireland, built between 1202 and 1285.
St. Nicholas Church, Vilnius, Lithuania, is the oldest surviving church in Lithuania. Originally built in the 14th century.
Hvalsey Church, located in Hvalsey (modern-day Qaqortoq), Greenland, Kingdom of Denmark, is the oldest surviving church (no longer in use, in ruins) in the Americas. Originally built in the 14th century as a Catholic church, although archaeology suggests it was constructed on the site of a previous church.

text: Early Modern[edit]

text: Notable early churches built in the New World between the 15th and 19th centuries. Listed are especially the oldest extant church buildings by country.

text:
St. Francis Church, Kochi, India, built 1504–1516, oldest European church building in India (Church of South India)
Catedral de Santa María la Menor, commissioned by Pope Julius II in 1504, and built 1514–1540. It is the oldest church in the Americas and the oldest church building in the Dominican Republic (Roman Catholic)
St. Paul's Church, Malacca, Malaysia,  built in 1521 as a Roman Catholic chapel and finally abandoned in 1753. It is the oldest known church building in Malaysia
Cathedral of San Juan Bautista, Puerto Rico, built in 1521, oldest church building in the United States (Roman Catholic)
Chapel of Ermita del Rosario, Mexico, built in 1523, oldest chapel in Mexico
The church of La Balbanera, Ecuador, was constructed in 1534, making it the oldest church constructed by the Spaniards in Ecuador
Chapel of San Jacinto, Guatemala, founded in 1524, one of the oldest churches in Guatemala (Roman Catholic)
Franciscan Chapel of the Red Cross, Jamaica, built in 1525, one of the oldest Spanish cathedrals in the New World (Roman Catholic)
St. Dominic's Church, Macau, China, built in 1527 by three Dominican Priests (Roman Catholic)
Church of Saints Cosme and Damião, built in 1535, in the city of Igarassu, Pernambuco. Brazil's oldest church (Roman Catholic).
Cebu Metropolitan Cathedral, Cebu, Philippines established in 1565, previously named as the Church of St. Vitales and is the first church erected in the Philippines.(Roman Catholic)
Mexico City Metropolitan Cathedral, built 1574–1813, one of the oldest churches in Mexico (Roman Catholic)
Old West Kirk, Greenock, 1591, the first Protestant church built in Scotland post Reformation (Church of Scotland)
Cathedral of the Immaculate Conception in Beijing, founded in 1604, possibly the oldest continuous church congregation in China (Roman Catholic)
San Agustin Church, Manila, built in 1607, one of the oldest church buildings in the Philippines. (Roman Catholic)
First Jamestown Church (foundations), 1607, first Protestant church in what would become the USA (Episcopal)
San Miguel Mission, Santa Fe, New Mexico, USA, built in 1610, oldest church building in the continental U.S. (Roman Catholic)
Ruins of St. Paul's, China, built in 1627 (Roman Catholic)
St. James Church, Barbados, founded 1627, oldest congregation in Barbados (Anglican)[citation needed]
St. Luke's Church, USA, built in 1632, oldest building in one of the original Thirteen Colonies (Episcopal)
Third Jamestown Church (tower), 1636 (Episcopal)
Old Ship Church, USA, built in 1681, the oldest church building in continuous use in continental U.S., oldest wooden church (Congregationalist, later Unitarian)
Notre-Dame-des-Victoires, Quebec City, built 1687–1723, later extensively rebuilt, Possibly the oldest church building in Canada (Roman Catholic)
Zion Church, Jakarta, Indonesia, the church was built in 1695, the oldest standing church structure in the city.
Cathedral of San Fernando, San Antonio, Texas, USA, built between 1738 and 1750, the oldest cathedral sanctuary in the United States
St. Paul's Church (Halifax), built 1750, Possibly the oldest Protestant church building in Canada (Anglican)
Blenduk Church, built in 1753 complete with a Baroque Organ from the 18th century, it is the oldest church in Central Java, Indonesia.
Christ Church Melaka, built in 1753 as a Dutch Reformed church, it now houses an Anglican congregation. It is the oldest Protestant church building in Malaysia
Mission San Diego de Alcalá, built in 1769 by Junipero Serra, is a functioning Roman Catholic church and the oldest in California (United States).  It sits at the base of El Camino Real, the road going northward in California that is punctuated by missions about a day's walk apart.
St. Anne's Church, constructed by the Portuguese in 1792, built in European and Gothic styles, one of the oldest Churches in South India, in Virajpet, Coorg.[52]
Her Majesty's Royal Chapel of the Mohawks, constructed in 1785 for the Mohawk people led by Joseph Brant, first Protestant church in Upper Canada (Anglican)
Church of the Holy Ascension, USA, built in 1826, oldest church building in Alaska (Russian Orthodox)
Armenian Church, Singapore, built 1835, oldest church in Singapore
Mokuaikaua Church, USA, built in 1837, oldest church congregation and building in Hawaii (Congregational)
Christ Church Royal Chapel, established in 1784, built in 1843 by the Mohawk people to symbolise their alliance with the British Crown (Anglican)
Saigon Notre-Dame Basilica, Possibly oldest church building in Vietnam, built 1863–1880 (Roman Catholic)
Ōura Church, built in 1864, Possibly the oldest church building in Japan (Roman Catholic)
Myeongdong Cathedral, built between 1892–1898, Oldest church building in South Korea (Roman Catholic)
Living Water Church, built 1909, One of the Oldest Pentecostal Church buildings in the World. Built 3 years after Azusa St. Revival in San Francisco, 1906 (Charismatic Church)


document_title: She's the Man

question_text: who plays the hairdresser in she's the man

question_tokens: who plays the hairdresser in she 's the man

root

text: She's the Man

text: Plot[edit]

text: Viola Hastings (Amanda Bynes) is a teen girl who plays for Cornwall College’s soccer team until the team gets cut. Meanwhile, her twin brother, Sebastian (James Kirk), is supposed to enroll in Illyria, an elite boarding school, but he secretly goes to London with his fledgling band instead. Viola agrees to cover for him and decides to pass herself off as Sebastian, in hopes of joining their boys' team and beating Cornwall to prove their coach and her cocky ex-boyfriend, Justin (Robert Hoffman), wrong. With the help of her stylist friend, Paul (Jonathan Sadowski), she is transformed into "Sebastian" and attends Illyria in his place.

tag: p

text: While moving in, she meets her roommate, Duke Orsino (Channing Tatum), an attractive soccer player and Illyria's team captain. During tryouts, Viola fails to impress Coach Dinklage (Vinnie Jones) and is assigned to second string, much to her dismay. Her teammates, including Duke, initially dislike "Sebastian" due to his awkward and strange behavior. However, with help from Paul once again, they begin to accept him into their social circle. "Sebastian" then gets the popular and pretty Olivia (Laura Ramsey) as his lab partner, which frustrates Duke, as he has feelings for her. "Sebastian" agrees to put in a good word for Duke if he promises to train him to be a better soccer player. Coach Dinklage eventually notices "Sebastian's" effort and improvement, thus promoting him to first string.

text: At the Junior League carnival, where her mother has made her volunteer, Viola works a shift at the kissing booth and shares a kiss with Duke. Duke expresses to "Sebastian" that he might move on from Olivia as he is starting to like Viola now. Viola is delighted as she secretly feels the same way.

text: Olivia who now has a crush on "Sebastian", asks Duke out on a date in hopes that it will make "Sebastian" jealous. Viola, who is unaware of Olivia's true intentions, is enraged instead because Duke has now abandoned his interest in Viola. When Viola finds out the truth, she encourages Olivia to tell "Sebastian" directly about her feelings.

text: The situation becomes even more complicated when the real Sebastian returns from London a day early, unbeknownst to Viola. As soon as he arrives at Illyria, Olivia confesses her feelings and kisses him. Duke, seeing this, believes his roommate has betrayed him. When "Sebastian" returns to their room, the two have an argument and Duke kicks him out. Viola oversleeps and misses the first half of the game, while the real Sebastian is mistaken for "Sebastian" and winds up poorly playing his sister's game instead. At half-time, Viola explains the situation to Sebastian and they switch places again.

text: Duke, still furious at "Sebastian", refuses to cooperate with him on the field. Determined to makes amends with Duke, "Sebastian" explains that he is actually Viola. Illyria wins the game when Viola scores a goal, finally humiliating Justin and the rest of the Cornwall boys.

text: Everyone at Illyria celebrates their victory over Cornwall, except for Duke who is hurt about Viola's deception. Viola introduces Sebastian and Olivia officially, and they begin dating. Viola and Sebastian's divorced parents also make up, exchanging contact information so as to be better parents towards their children. She invites Duke to her debutante ball, with an invitation delivered by Sebastian, now Duke's roommate. Still hurt, Duke doesn't respond to Viola's invitation, which devastates her. At the ball, Viola is skeptical that Duke will show up; she distracts herself by assisting Olivia, who is being escorted by Sebastian to the ball, and is touched when Paul asks to be her date. Her mother shows up with a dress that will suit Viola's "no ruffles" policy, but Viola decides to go for a walk instead. She runs into Duke outside, who tells her that he has feelings for her, but that he doesn't want there to be any more deception on her part; Viola promises to be honest with him. Later, Monique is escorted by Justin, Olivia is escorted by Sebastian, and Viola and Duke enter the stage late, but together, with Viola in her new dress, much to the joy of her mother. Viola and Duke share a kiss before joining the crowd. At the end of the film, Viola and Duke are shown happily playing on Illyria's soccer team together.

text: Cast[edit]

text:
Amanda Bynes as Viola/Sebastian Hastings
Channing Tatum as Duke Orsino
Laura Ramsey as Olivia Lennox
Emily Perkins as Eunice Bates, Olivia's nerdy, eccentric friend and Duke's lab partner
James Snyder as Malcolm Festes, the school nerd and Sebastian's (Viola's) rival
Robert Hoffman as Justin Drayton, Viola's ex-boyfriend and Duke's rival
James Kirk as Sebastian Hastings
Alex Breckenridge as Monique Valentine, Sebastian's superficial girlfriend
Brandon Jay McLaren as Toby, one of Duke's best friends
Clifton Murray as Andrew, one of Duke's best friends
Jonathan Sadowski as Paul Antonio, one of Viola's best friends and hair stylist
Amanda Crew as Kia, one of Viola's best friends
Jessica Lucas as Yvonne, one of Viola's best friends
David Cross as Principal Horatio Gold
Vinnie Jones as Coach Dinklage
Julie Hagerty as Daphne Hastings, the mother of Viola and Sebastian
John Pyper-Ferguson as Roger Hastings, the father of Viola and Sebastian
Lynda Boyd as Cheryl, the debutante ball's hostess
Robert Torti as Coach Pistonek
Mark Acheson as Groundskeeper

tag: ul

text: Reception[edit]

text: Box office[edit]

text: The film opened at #4 at the North American box office making $10.7 million USD in its opening weekend. Its budget was approximately $20,000,000. She's the Man grossed a total of $33.7 million domestically with a total gross of $57.2 million worldwide.[1]

text: Critical response[edit]

text: Review aggregation website Rotten Tomatoes gave She's the Man a rating of 43%, based on 109 reviews. The critical consensus reads, "Shakespeare's wit gets lost in translation with She's the Man's broad slapstick, predictable jokes, and unconvincing plotline."[3] Metacritic, which assigns a weighted mean rating out of 100 reviews from film critics, the film has a rating score of 45 out of 100 based on 28 reviews, indicating "mixed or average reviews".[4]


document_title: CT scan

question_text: in which decade was the ct scanner developed

question_tokens: in which decade was the ct scanner developed

text: CT scan

text: Medical use[edit]

text: Since its introduction in the 1970s, CT has become an important tool in medical imaging to supplement X-rays and medical ultrasonography. It has more recently been used for preventive medicine or screening for disease, for example CT colonography for people with a high risk of colon cancer, or full-motion heart scans for people with high risk of heart disease. A number of institutions offer full-body scans for the general population although this practice goes against the advice and official position of many professional organizations in the field primarily due to the radiation dose applied.[12]

text: Head[edit]

text: CT scanning of the head is typically used to detect infarction, tumors, calcifications, haemorrhage and bone trauma. Of the above, hypodense (dark) structures can indicate edema and infarction, hyperdense (bright) structures indicate calcifications and haemorrhage and bone trauma can be seen as disjunction in bone windows. Tumors can be detected by the swelling and anatomical distortion they cause, or by surrounding edema. Ambulances equipped with small bore multi-sliced CT scanners respond to cases involving stroke or head trauma. CT scanning of the head is also used in CT-guided stereotactic surgery and radiosurgery for treatment of intracranial tumors, arteriovenous malformations and other surgically treatable conditions using a device known as the N-localizer.[13][14][15][16][17][18]

text: Magnetic resonance imaging (MRI) of the head provides superior information as compared to CT scans when seeking information about headache to confirm a diagnosis of neoplasm, vascular disease, posterior cranial fossa lesions, cervicomedullary lesions, or intracranial pressure disorders.[19] It also does not carry the risks of exposing the patient to ionizing radiation.[19] CT scans may be used to diagnose headache when neuroimaging is indicated and MRI is not available, or in emergency settings when hemorrhage, stroke, or traumatic brain injury are suspected.[19] Even in emergency situations, when a head injury is minor as determined by a physician's evaluation and based on established guidelines, CT of the head should be avoided for adults and delayed pending clinical observation in the emergency department for children.[20]

text: Lungs[edit]

text: CT scan can be used for detecting both acute and chronic changes in the lung parenchyma, that is, the internals of the lungs. It is particularly relevant here because normal two-dimensional X-rays do not show such defects. A variety of techniques are used, depending on the suspected abnormality. For evaluation of chronic interstitial processes (emphysema, fibrosis, and so forth), thin sections with high spatial frequency reconstructions are used; often scans are performed both in inspiration and expiration. This special technique is called high resolution CT. Therefore, it produces a sampling of the lung and not continuous images.

text: Bronchial wall thickening can be seen on lung CTs, and generally (but not always) impies inflammation of the bronchi.[21] Normally, the ratio of the bronchial wall thickness and the bronchial diameter is between 0.17 and 0.23.[22]

text: An incidentally found nodule in the absence of symptoms (sometimes referred to as an incidentaloma) may raise concerns that it might represent a tumor, either benign or malignant.[23] Perhaps persuaded by fear, patients and doctors sometimes agree to an intensive schedule of CT scans, sometimes up to every three months and beyond the recommended guidelines, in an attempt to do surveillance on the nodules.[24] However, established guidelines advise that patients without a prior history of cancer and whose solid nodules have not grown over a two-year period are unlikely to have any malignant cancer.[24] For this reason, and because no research provides supporting evidence that intensive surveillance gives better outcomes, and because of risks associated with having CT scans, patients should not receive CT screening in excess of those recommended by established guidelines.[24]

text: Angiography[edit]

text: Computed tomography angiography (CTA) is contrast CT to visualize arterial and venous vessels throughout the body. This ranges from arteries serving the brain to those bringing blood to the lungs, kidneys, arms and legs. An example of this type of exam is CT pulmonary angiogram (CTPA) used to diagnose pulmonary embolism (PE). It employs computed tomography and an iodine based contrast agent to obtain an image of the pulmonary arteries.

text: Cardiac[edit]

text: A CT scan of the heart is performed to gain knowledge about cardiac or coronary anatomy.[25] Traditionally, cardiac CT scans are used to detect, diagnose or follow up coronary artery disease.[26] More recently CT has played a key role in the fast evolving field of transcatheter structural heart interventions, more specifically in the transcatheter repair and replacement of heart valves.[27][28][29]

text: The main forms of cardiac CT scanning are:

text:
Coronary CT angiography (CTA): the use of CT to assess the coronary arteries of the heart. The subject receives an intravenous injection of radiocontrast and then the heart is scanned using a high speed CT scanner, allowing radiologists to assess the extent of occlusion in the coronary arteries, usually in order to diagnose coronary artery disease.
Coronary CT calcium scan: also used for the assessment of severity of coronary artery disease. Specifically, it looks for calcium deposits in the coronary arteries that can narrow arteries and increase the risk of heart attack.[30] A typical coronary CT calcium scan is done without the use of radiocontrast, but it can possibly be done from contrast-enhanced images as well.[31]

text: To better visualize the anatomy, post-processing of the images is common.[26] Most common are multiplanar reconstructions (MPR) and volume rendering. For more complex anatomies and procedures, such as heart valve interventions, a true 3D reconstruction or a 3D print is created based on these CT images to gain a deeper understanding.[32][33][34][35]

text: Abdominal and pelvic[edit]

text: CT is an accurate technique for diagnosis of abdominal diseases. Its uses include diagnosis and staging of cancer, as well as follow up after cancer treatment to assess response. It is commonly used to investigate acute abdominal pain.

text: Extremities[edit]

text: CT is often used to image complex fractures, especially ones around joints, because of its ability to reconstruct the area of interest in multiple planes. Fractures, ligamentous injuries and dislocations can easily be recognised with a 0.2 mm resolution.[36][37] With modern Dual-energy CT scanners, new areas of use have been established, such as aiding in the diagnosis of gout.[38]

text: Advantages[edit]

text: There are several advantages that CT has over traditional 2D medical radiography. First, CT completely eliminates the superimposition of images of structures outside the area of interest. Second, because of the inherent high-contrast resolution of CT, differences between tissues that differ in physical density by less than 1% can be distinguished. Finally, data from a single CT imaging procedure consisting of either multiple contiguous or one helical scan can be viewed as images in the axial, coronal, or sagittal planes, depending on the diagnostic task. This is referred to as multiplanar reformatted imaging.

text: CT is regarded as a moderate- to high-radiation diagnostic technique. The improved resolution of CT has permitted the development of new investigations, which may have advantages; compared to conventional radiography, for example, CT angiography avoids the invasive insertion of a catheter. CT colonography (also known as virtual colonoscopy or VC for short) is far more accurate than a barium enema for detection of tumors, and uses a lower radiation dose. CT VC is increasingly being used in the UK and US as a screening test for colon polyps and colon cancer and can negate the need for a colonoscopy in some cases.

text: The radiation dose for a particular study depends on multiple factors: volume scanned, patient build, number and type of scan sequences, and desired resolution and image quality.[39] In addition, two helical CT scanning parameters that can be adjusted easily and that have a profound effect on radiation dose are tube current and pitch. Computed tomography (CT) scan has been shown to be more accurate than radiographs in evaluating anterior interbody fusion but may still over-read the extent of fusion.[40]

text: Adverse effects[edit]

text: Cancer[edit]

text: The radiation used in CT scans can damage body cells, including DNA molecules, which can lead to cancer.[8] According to the National Council on Radiation Protection and Measurements, between the 1980s and 2006, the use of CT scans has increased sixfold (+500%). The radiation doses received from CT scans is variable. Compared to the lowest dose x-ray techniques, CT scans can have 100 to 1,000 times higher dose than conventional X-rays.[41] However, a lumbar spine x-ray has a similar dose as a head CT.[42] Articles in the media often exaggerate the relative dose of CT by comparing the lowest dose x-ray techniques (chest x-ray) with the highest dose CT techniques. In general, the radiation dose associated with a routine abdominal CT has a radiation dose similar to 3 years average background radiation (from cosmic radiation).[43]

text: Some experts note that CT scans are known to be "overused," and "there is distressingly little evidence of better health outcomes associated with the current high rate of scans."[41]

text: Early estimates of harm from CT are partly based on similar radiation exposures experienced by those present during the atomic bomb explosions in Japan after the Second World War and those of nuclear industry workers.[8] A more recent study by the National Cancer Institute in 2009, based on scans made in 2007, estimated that 29,000 excess cancer cases and 14,500 excess deaths would be caused over the lifetime of the patients. Some experts project that in the future, between three and five percent of all cancers would result from medical imaging.[41]

text: An Australian study of 10.9 million people reported that the increased incidence of cancer after CT scan exposure in this cohort was mostly due to irradiation. In this group one in every 1800 CT scans was followed by an excess cancer. If the lifetime risk of developing cancer is 40% then the absolute risk rises to 40.05% after a CT.[44][45]

text: A person's age plays a significant role in the subsequent risk of cancer.[46] Estimated lifetime cancer mortality risks from an abdominal CT of a 1-year-old is 0.1% or 1:1000 scans.[46] The risk for someone who is 40 years old is half that of someone who is 20 years old with substantially less risk in the elderly.[46] The International Commission on Radiological Protection estimates that the risk to a fetus being exposed to 10 mGy (a unit of radiation exposure, see Gray (unit)) increases the rate of cancer before 20 years of age from 0.03% to 0.04% (for reference a CT pulmonary angiogram exposes a fetus to 4 mGy).[47] A 2012 review did not find an association between medical radiation and cancer risk in children noting however the existence of limitations in the evidences over which the review is based.[48]

text: CT scans can be performed with different settings for lower exposure in children with most manufacturers of CT scans as of 2007 having this function built in.[49] Furthermore, certain conditions can require children to be exposed to multiple CT scans.[8] Studies support informing parents of the risks of pediatric CT scanning.[50]

text: Contrast reactions[edit]

text: In the United States half of CT scans are contrast CTs using intravenously injected radiocontrast agents.[51] The most common reactions from these agents are mild, including nausea, vomiting and an itching rash; however, more severe reactions may occur.[52] Overall reactions occur in 1 to 3% with nonionic contrast and 4 to 12% of people with ionic contrast.[53] Skin rashes may appear within a week to 3% of people.[52]

text: The old radiocontrast agents caused anaphylaxis in 1% of cases while the newer, lower-osmolar agents cause reactions in 0.01–0.04% of cases.[52][54] Death occurs in about two to 30 people per 1,000,000 administrations, with newer agents being safer.[53][55] There is a higher risk of mortality in those who are female, elderly or in poor health, usually secondary to either anaphylaxis or acute renal failure.[51]

text: The contrast agent may induce contrast-induced nephropathy.[11] This occurs in 2 to 7% of people who receive these agents, with greater risk in those who have preexisting renal insufficiency,[11] preexisting diabetes, or reduced intravascular volume. People with mild kidney impairment are usually advised to ensure full hydration for several hours before and after the injection. For moderate kidney failure, the use of iodinated contrast should be avoided; this may mean using an alternative technique instead of CT. Those with severe renal failure requiring dialysis require less strict precautions, as their kidneys have so little function remaining that any further damage would not be noticeable and the dialysis will remove the contrast agent; it is normally recommended, however, to arrange dialysis as soon as possible following contrast administration to minimize any adverse effects of the contrast.

text: In addition to the use of intravenous contrast, orally administered contrast agents are frequently used when examining the abdomen. These are frequently the same as the intravenous contrast agents, merely diluted to approximately 10% of the concentration. However, oral alternatives to iodinated contrast exist, such as very dilute (0.5–1% w/v) barium sulfate suspensions. Dilute barium sulfate has the advantage that it does not cause allergic-type reactions or kidney failure, but cannot be used in patients with suspected bowel perforation or suspected bowel injury, as leakage of barium sulfate from damaged bowel can cause fatal peritonitis.

text: Process[edit]

text: Computed tomography operates by using an X-ray generator that rotates around the object; X-ray detectors are positioned on the opposite side of the circle from the X-ray source. A visual representation of the raw data obtained is called a sinogram, yet it is not sufficient for interpretation. Once the scan data has been acquired, the data must be processed using a form of tomographic reconstruction, which produces a series of cross-sectional images. Pixels in an image obtained by CT scanning are displayed in terms of relative radiodensity. The pixel itself is displayed according to the mean attenuation of the tissue(s) that it corresponds to on a scale from +3071 (most attenuating) to −1024 (least attenuating) on the Hounsfield scale. Pixel is a two dimensional unit based on the matrix size and the field of view. When the CT slice thickness is also factored in, the unit is known as a Voxel, which is a three-dimensional unit. The phenomenon that one part of the detector cannot differentiate between different tissues is called the "Partial Volume Effect". That means that a big amount of cartilage and a thin layer of compact bone can cause the same attenuation in a voxel as hyperdense cartilage alone. Water has an attenuation of 0 Hounsfield units (HU), while air is −1000 HU, cancellous bone is typically +400 HU, cranial bone can reach 2000 HU or more (os temporale) and can cause artifacts. The attenuation of metallic implants depends on atomic number of the element used: Titanium usually has an amount of +1000 HU, iron steel can completely extinguish the X-ray and is, therefore, responsible for well-known line-artifacts in computed tomograms. Artifacts are caused by abrupt transitions between low- and high-density materials, which results in data values that exceed the dynamic range of the processing electronics. Two-dimensional CT images are conventionally rendered so that the view is as though looking up at it from the patient's feet.[57] Hence, the left side of the image is to the patient's right and vice versa, while anterior in the image also is the patient's anterior and vice versa. This left-right interchange corresponds to the view that physicians generally have in reality when positioned in front of patients. CT data sets have a very high dynamic range which must be reduced for display or printing. This is typically done via a process of "windowing", which maps a range (the "window") of pixel values to a grayscale ramp. For example, CT images of the brain are commonly viewed with a window extending from 0 HU to 80 HU. Pixel values of 0 and lower, are displayed as black; values of 80 and higher are displayed as white; values within the window are displayed as a grey intensity proportional to position within the window. The window used for display must be matched to the X-ray density of the object of interest, in order to optimize the visible detail.

text: Contrast[edit]

text: Contrast media used for X-ray CT, as well as for plain film X-ray, are called radiocontrasts. Radiocontrasts for X-ray CT are, in general, iodine-based.[58] This is useful to highlight structures such as blood vessels that otherwise would be difficult to delineate from their surroundings. Using contrast material can also help to obtain functional information about tissues. Often, images are taken both with and without radiocontrast.

text: Scan dose[edit]

text:
Examination
Typical effective
dose (mSv)
to the whole body
Typical absorbed
dose (mGy)
to the organ in question

Annual background radiation
2.4[59]
2.4[59]

Chest X-ray
0.02[60]
0.01–0.15[61]

Head CT
1–2[46]
56[62]

Screening mammography
0.4[47]
3[8][61]

Abdomen CT
8[60]
14[62]

Chest CT
5–7[46]
13[62]

CT colonography
6–11[46]

Chest, abdomen and pelvis CT
9.9[62]
12[62]

Cardiac CT angiogram
9–12[46]
40–100[61]

Barium enema
15[8]
15[61]

Neonatal abdominal CT
20[8]
20[61]

tag: table

text: The table reports average radiation exposures, however, there can be a wide variation in radiation doses between similar scan types, where the highest dose could be as much as 22 times higher than the lowest dose.[46] A typical plain film X-ray involves radiation dose of 0.01 to 0.15 mGy, while a typical CT can involve 10–20 mGy for specific organs, and can go up to 80 mGy for certain specialized CT scans.[61]

text: For purposes of comparison, the world average dose rate from naturally occurring sources of background radiation is 2.4 mSv per year, equal for practical purposes in this application to 2.4 mGy per year.[59] While there is some variation, most people (99%) received less than 7 mSv per year as background radiation.[63] Medical imaging as of 2007 accounted for half of the radiation exposure of those in the United States with CT scans making up two thirds of this amount.[46] In the United Kingdom it accounts for 15% of radiation exposure.[47] The average radiation dose from medical sources is ≈0.6 mSv per person globally as of 2007.[46] Those in the nuclear industry in the United States are limited to doses of 50 mSv a year and 100 mSv every 5 years.[46]

text: Lead is the main material used by radiography personnel for shielding against scattered X-rays.

text: Radiation dose units[edit]

text: The radiation dose reported in the gray or mGy unit is proportional to the amount of energy that the irradiated body part is expected to absorb, and the physical effect (such as DNA double strand breaks) on the cells' chemical bonds by X-ray radiation is proportional to that energy.[64]

text: The sievert unit is used in the report of the effective dose. The sievert unit, in the context of CT scans, does not correspond to the actual radiation dose that the scanned body part absorbs but to another radiation dose of another scenario, the whole body absorbing the other radiation dose and the other radiation dose being of a magnitude, estimated to have the same probability to induce cancer as the CT scan.[65] Thus, as is shown in the table above, the actual radiation that is absorbed by a scanned body part is often much larger than the effective dose suggests. A specific measure, termed the computed tomography dose index (CTDI), is commonly used as an estimate of the radiation absorbed dose for tissue within the scan region, and is automatically computed by medical CT scanners.[66]

text: The equivalent dose is the effective dose of a case, in which the whole body would actually absorb the same radiation dose, and the sievert unit is used in its report. In the case of non-uniform radiation, or radiation given to only part of the body, which is common for CT examinations, using the local equivalent dose alone would overstate the biological risks to the entire organism.

text: Effects of radiation[edit]

text: Most adverse health effects of radiation exposure may be grouped in two general categories:

text:
deterministic effects (harmful tissue reactions) due in large part to the killing/ malfunction of cells following high doses; and
stochastic effects, i.e., cancer and heritable effects involving either cancer development in exposed individuals owing to mutation of somatic cells or heritable disease in their offspring owing to mutation of reproductive (germ) cells.[67]

text: The added lifetime risk of developing cancer by a single abdominal CT of 8 mSv is estimated to be 0.05%, or 1 one in 2,000.[68]

text: Because of increased susceptibility of fetuses to radiation exposure, the radiation dosage of a CT scan is an important consideration in the choice of medical imaging in pregnancy.

text: Excess doses[edit]

text: In October, 2009, the US Food and Drug Administration (FDA) initiated an investigation of brain perfusion CT (PCT) scans, based on overdoses of radiation caused by incorrect settings at one particular facility for this particular type of CT scan. Over 256 patients over an 18-month period were exposed, over 40% lost patches of hair, and prompted the editorial to call for increased CT quality assurance programs, while also noting that "while unnecessary radiation exposure should be avoided, a medically needed CT scan obtained with appropriate acquisition parameter has benefits that outweigh the radiation risks."[46][69] Similar problems have been reported at other centers.[46] These incidents are believed to be due to human error.[46]

text: Campaigns[edit]

text: In response to increased concern by the public and the ongoing progress of best practices, The Alliance for Radiation Safety in Pediatric Imaging was formed within the Society for Pediatric Radiology. In concert with The American Society of Radiologic Technologists, The American College of Radiology and The American Association of Physicists in Medicine, the Society for Pediatric Radiology developed and launched the Image Gently Campaign which is designed to maintain high quality imaging studies while using the lowest doses and best radiation safety practices available on pediatric patients.[70] This initiative has been endorsed and applied by a growing list of various professional medical organizations around the world and has received support and assistance from companies that manufacture equipment used in Radiology.

text: Following upon the success of the Image Gently campaign, the American College of Radiology, the Radiological Society of North America, the American Association of Physicists in Medicine and the American Society of Radiologic Technologists have launched a similar campaign to address this issue in the adult population called Image Wisely.[71]

text: The World Health Organization and International Atomic Energy Agency (IAEA) of the United Nations have also been working in this area and have ongoing projects designed to broaden best practices and lower patient radiation dose.[72][73]

text: Prevalence[edit]

text: Use of CT has increased dramatically over the last two decades.[6] An estimated 72 million scans were performed in the United States in 2007.[7] Of these, six to eleven percent are done in children,[47] an increase of seven to eightfold from 1980.[46] Similar increases have been seen in Europe and Asia.[46] In Calgary, Canada 12.1% of people who present to the emergency with an urgent complaint received a CT scan, most commonly either of the head or of the abdomen. The percentage who received CT, however, varied markedly by the emergency physician who saw them from 1.8% to 25%.[74] In the emergency department in the United States, CT or MRI imaging is done in 15% of people who present with injuries as of 2007 (up from 6% in 1998).[75]

text: The increased use of CT scans has been the greatest in two fields: screening of adults (screening CT of the lung in smokers, virtual colonoscopy, CT cardiac screening, and whole-body CT in asymptomatic patients) and CT imaging of children. Shortening of the scanning time to around 1 second, eliminating the strict need for the subject to remain still or be sedated, is one of the main reasons for the large increase in the pediatric population (especially for the diagnosis of appendicitis).[8] As of 2007 in the United States a proportion of CT scans are performed unnecessarily.[49] Some estimates place this number at 30%.[47] There are a number of reasons for this including: legal concerns, financial incentives, and desire by the public.[49] For example, some healthy people avidly pay to receive full-body CT scans as screening, but it is not at all clear that the benefits outweigh the risks and costs, because deciding whether and how to treat incidentalomas is fraught with complexity, radiation exposure is cumulative and not negligible, and the money for the scans involves opportunity cost (it may have been more effectively spent on more targeted screening or other health care strategies).[49]

text: Presentation[edit]

text: The result of a CT scan is a volume of voxels, which may be presented to a human observer by various methods, which broadly fit into the following categories:

text:
Thin slice. This is generally regarded as planes representing a thickness of less than 3 mm.[76]
Projection, including maximum intensity projection[77] and average intensity projection
Volume rendering (VR)[77]

text: Technically, all volume renderings become projections when viewed on a 2-dimensional display, making the distinction between projections and volume renderings a bit vague. Still, the epitomes of volume rendering models feature a mix of for example coloring[78] and shading[79] in order to create realistic and observable representations.

text: Two-dimensional CT images are conventionally rendered so that the view is as though looking up at it from the patient's feet.[80] Hence, the left side of the image is to the patient's right and vice versa, while anterior in the image also is the patient's anterior and vice versa. This left-right interchange corresponds to the view that physicians generally have in reality when positioned in front of patients.

text: Grayscale[edit]

text: Projections[edit]

text: Projections include maximum intensity projection (MIP), which enhance areas of high radiodensity, and so are useful for angiographic studies. MIP reconstructions tend to enhance air spaces so are useful for assessing lung structure.

text: Average intensity projection essentially imitates conventional projectional radiography, but can be used for specific volumes within the human body.

text: Multiplanar reconstruction[edit]

text: Multiplanar reconstruction (MPR) is the creation of slices in more anatomical planes than the one (usually transverse) used for initial tomography acquisition. It can be used for thin slices as well as projections. Multiplanar reconstruction is feasible because contemporary CT scanners offer isotropic or near isotropic resolution.[81]

text: MPR is frequently used for examining the spine. Axial images through the spine will only show one vertebral body at a time and cannot reliably show the intervertebral discs. By reformatting the volume, it becomes much easier to visualise the position of one vertebral body in relation to the others.

text: Modern software allows reconstruction in non-orthogonal (oblique) planes so that the optimal plane can be chosen to display an anatomical structure. This may be particularly useful for visualising the structure of the bronchi as these do not lie orthogonal to the direction of the scan.

text: For vascular imaging, curved-plane reconstruction can be performed. This allows bends in a vessel to be "straightened" so that the entire length can be visualised on one image, or a short series of images. Once a vessel has been "straightened" in this way, quantitative measurements of length and cross sectional area can be made, so that surgery or interventional treatment can be planned.

text: Volume rendering[edit]

text: A threshold value of radiodensity is set by the operator (e.g., a level that corresponds to bone). From this, a three-dimensional model can be constructed using edge detection image processing algorithms and displayed on screen. Multiple models can be constructed from various thresholds, allowing different colors to represent each anatomical component such as bone, muscle, and cartilage. However, the interior structure of each element is not visible in this mode of operation.

text: Surface rendering is limited in that it will display only surfaces that meet a threshold density, and will display only the surface that is closest to the imaginary viewer. In volume rendering, transparency, colors and shading are used to allow a better representation of the volume to be shown in a single image. For example, the bones of the pelvis could be displayed as semi-transparent, so that, even at an oblique angle, one part of the image does not conceal another.

text: Image quality[edit]

text: Artifacts[edit]

text: Although images produced by CT are generally faithful representations of the scanned volume, the technique is susceptible to a number of artifacts, such as the following:[2][82]Chapters 3 and 5

text: Dose versus image quality[edit]

text: An important issue within radiology today is how to reduce the radiation dose during CT examinations without compromising the image quality. In general, higher radiation doses result in higher-resolution images,[93] while lower doses lead to increased image noise and unsharp images. However, increased dosage raises the adverse side effects, including the risk of radiation induced cancer – a four-phase abdominal CT gives the same radiation dose as 300 chest X-rays (See the Scan dose section). Several methods that can reduce the exposure to ionizing radiation during a CT scan exist.[94]

text:
New software technology can significantly reduce the required radiation dose.
Individualize the examination and adjust the radiation dose to the body type and body organ examined. Different body types and organs require different amounts of radiation.
Prior to every CT examination, evaluate the appropriateness of the exam whether it is motivated or if another type of examination is more suitable. Higher resolution is not always suitable for any given scenario, such as detection of small pulmonary masses.[95]

tag: ol

text: Industrial use[edit]

text: Industrial CT Scanning (industrial computed tomography) is a process which utilizes X-ray equipment to produce 3D representations of components both externally and internally. Industrial CT scanning has been utilized in many areas of industry for internal inspection of components. Some of the key uses for CT scanning have been flaw detection, failure analysis, metrology, assembly analysis, image-based finite element methods[96] and reverse engineering applications. CT scanning is also employed in the imaging and conservation of museum artifacts.[97]

text: CT scanning has also found an application in transport security (predominantly airport security where it is currently used in a materials analysis context for explosives detection CTX (explosive-detection device)[98][99][100] and is also under consideration for automated baggage/parcel security scanning using computer vision based object recognition algorithms that target the detection of specific threat items based on 3D appearance (e.g. guns, knives, liquid containers).[101][102][103]

text: History[edit]

text: The history of X-ray computed tomography goes back to at least 1917 with the mathematical theory of the Radon transform.[104][105] In October 1963, Oldendorf received a U.S. patent for a "radiant energy apparatus for investigating selected areas of interior objects obscured by dense material".[106] The first commercially viable CT scanner was invented by Sir Godfrey Hounsfield in 1967.[107]

text: Etymology[edit]

text: The word "tomography" is derived from the Greek tome (slice) and graphein (to write). Computed tomography was originally known as the "EMI scan" as it was developed in the early 1970s at a research branch of EMI, a company best known today for its music and recording business. It was later known as computed axial tomography (CAT or CT scan) and body section röntgenography.

text: Although the term "computed tomography" could be used to describe positron emission tomography or single photon emission computed tomography (SPECT), in practice it usually refers to the computation of tomography from X-ray images, especially in older medical literature and smaller medical facilities.

text: In MeSH, "computed axial tomography" was used from 1977 to 1979, but the current indexing explicitly includes "X-ray" in the title.[108]

text: The term sinogram was introduced by Paul Edholm and Bertil Jacobson in 1975.[109]

text: Types of machines[edit]

text: Spinning tube, commonly called spiral CT, or helical CT is an imaging technique in which an entire X-ray tube is spun around the central axis of the area being scanned. These are the dominant type of scanners on the market because they have been manufactured longer and offer lower cost of production and purchase. The main limitation of this type is the bulk and inertia of the equipment (X-ray tube assembly and detector array on the opposite side of the circle) which limits the speed at which the equipment can spin. Some designs use two X-ray sources and detector arrays offset by an angle, as a technique to improve temporal resolution.

text: Electron beam tomography (EBT) is a specific form of CT in which a large enough X-ray tube is constructed so that only the path of the electrons, travelling between the cathode and anode of the X-ray tube, are spun using deflection coils. This type had a major advantage since sweep speeds can be much faster, allowing for less blurry imaging of moving structures, such as the heart and arteries. Fewer scanners of this design have been produced when compared with spinning tube types, mainly due to the higher cost associated with building a much larger X-ray tube and detector array and limited anatomical coverage. Only one manufacturer (Imatron, later acquired by General Electric) ever produced scanners of this design. Production ceased in early 2006.[110]

text: In multislice computed tomography (MSCT), a higher number of tomographic slices allow for higher-resolution imaging.

text: Research directions[edit]

text: Photon counting computed tomography is a CT technique currently under development. Typical CT scanners use energy integrating detectors; photons are measured as a voltage on a capacitor which is proportional to the x-rays detected. However, this technique is susceptible to noise and other factors which can affect the linearity of the voltage to x-ray intensity relationship.[111] Photon counting detectors (PCDs) are still affected by noise but it does not change the measured counts of photons. PCDs have several potential advantages including improving signal (and contrast) to noise ratios, reducing doses, improving spatial resolution and, through use of several energies, distinguishing multiple contrast agents.[112][113] PCDs have only recently become feasible in CT scanners due to improvements in detector technologies that can cope with the volume and rate of data required. As of February 2016 photon counting CT is in use at three sites.[114] Some early research has found the dose reduction potential of photon counting CT for breast imaging to be very promising.[115]