Historical developmentThe first suc

Historical development
The first successful demonstration of CT was conducted in 1970 in England, at the central research laboratory of EMI. Dr. Godfrey Hounsfield, an engineer for EMI, and Dr.james Ambrose, a physician at Atkinson morley’s Hospital in London,England, are generally given credit for development of CT. their research was awarded the nobel price in 1979. After CT was shown to be a usefull clinical imaging modality, the first full-scale commercial unit, referred to as a “brain tissue scanner”, was installed in Atkinson morley’s hospital in 1971. An example of an early dedicated head CT scanner is seen in (gambar). Physicians recognized its value for providing diagnostic neurologic information, and its use became accepted rapidly. The first CT scanners in the united states were installed in june 1973 at the mayo clinic and later that year at Massachusetts general hospital. Both of these early units were also dedicated head scanners. In 1974 Dr.robert S.ledley of Georgetown university medical center developed the first whole bode scanner, wich greatly expanded the diagnostic capabilities of CT.
After CT was accepted bu physicians as diagnostic modality, numerous companies in addition to EMI began manufacturing scanners. Although there were differences in the design of units, the basic principles of operation were the same. CT scanners have been categorized by generation, which is a reference to the level of technological advancement of the tube and detector assembly. There were four recognized generations of CT scanners, Although newer scanners are no longer categorized by generation but by tube nad detector movement
The early units, referred to as the first generation scanners, worked by a process known as translation/rotation. The tube produced a finely collimated beam; or pencil beam. Depending on the manufacturer, one to three detectors were placed opposite the tube for radiation detection. The tube movement (translation) was followed by a rotation of 1 degree. Scan time was usually 3 to 5 minutes per scan, which required the patient to hold still for extended periods. Because of the slow scanning and reconstruction time, CT was limited almost exlusively to neurologic examinations; an example of a CT image from a first generation scanner is seen in (gambar)
When the second generation of scanners was introduced, they were considered a significant improvement over first generation scanners. The fan beam and multiple detectors were introduced by manufacturers for better radiation production and detection. Tube and detector movement was still translation/rotation, but the rotation was 10 degress between each translation. These changes improved overall image quality and decreased scan time to about 20 seconds for a single slice. However, the time required to complete on CT examination remained relatively long.
The third generation of scanners introduced the rotate/rotate movement, in which the tube and detector assembly revolved concentrically about the body part. Scan time were decreased to 1 to 10 seconds per slice, which made scans much easier for patients and helped to decrease motion artifact. Advencements in computer technology also decreased image reconstruction time, resulting in a substantial reduction in examination time.
The next major change in CT scanner design, the fourth generation, introduced the rotate-only movement, in which the tube rotated about the patient, but the detectors were stationary in fixed postions within the gantry. The use of stationary detectors required greater numbers of detectors to be installed in a scanner. Fourth generation scanners tended to yield a higher patient dose per scan than previous generations.

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Perkembangan sejarahDemonstrasi sukses pertama CT dilaksanakan pada tahun 1970 di Inggris, di pusat penelitian laboratorium EMI. Dr Godfrey Hounsfield, seorang insinyur untuk EMI, dan Dr.james Ambrose, seorang dokter di Atkinson morley Hospital di London, England, umumnya diberikan kredit untuk pengembangan CT. penelitian mereka dianugerahi nobel harga pada tahun 1979. Setelah CT ditunjukkan untuk menjadi berguna klinis modalitas pencitraan, unit komersial skala penuh yang pertama, yang disebut sebagai "scanner jaringan otak", dipasang pada Atkinson morley rumah sakit pada tahun 1971. Contoh awal berdedikasi kepala CT scanner dilihat dalam (gambar). Dokter mengakui nilai untuk menyediakan informasi neurologis diagnostik, dan penggunaannya menjadi diterima dengan cepat. CT scanner pertama di Amerika Serikat dipasang di Juni 1973 di mayo clinic dan kemudian di tahun itu di rumah sakit umum Massachusetts. Kedua unit ini awal yang berdedikasi kepala scanner. Pada tahun 1974 Dr.robert S.ledley Georgetown university medical Center mengembangkan seluruh pertama pertanda scanner, yang sangat memperluas kemampuan diagnostik CT.Setelah CT dokter bu diterima sebagai modalitas diagnostik, sejumlah perusahaan selain EMI mulai manufaktur scanner. Walaupun ada perbedaan dalam desain unit, prinsip-prinsip dasar operasi yang sama. CT scanner telah dikategorikan oleh generasi, yang merupakan referensi untuk tingkat kemajuan teknologi Majelis tabung dan detektor. Ada empat generasi diakui CT scanner, meskipun scanner baru tidak lagi dikategorikan oleh generasi tapi tabung nad detektor gerakanUnit awal, disebut sebagai generasi pertama scanner, bekerja dengan proses yang dikenal sebagai terjemahan rotasi. Tabung diproduksi balok halus collimated; atau pensil balok. Tergantung pada produsen, satu sampai tiga detektor ditempatkan berlawanan tabung untuk mendeteksi radiasi. Gerakan tabung (terjemahan) diikuti oleh rotasi dari 1 derajat. Scan waktu itu biasanya 3-5 menit per scan, yang diperlukan pasien untuk menahan masih untuk waktu yang lama. Karena lambat pemindaian dan waktu rekonstruksi, CT adalah terbatas hampir exlusively untuk pemeriksaan neurologis; contoh gambar CT dari scanner generasi pertama terlihat dalam (gambar)Ketika generasi kedua scanner diperkenalkan, mereka dianggap peningkatan yang signifikan atas scanner generasi pertama. Sinar penggemar dan beberapa detektor diperkenalkan oleh produsen untuk lebih baik radiasi produksi dan deteksi. Tabung dan detektor gerakan masih terjemahan rotasi, tapi rotasi 10 degress antara setiap terjemahan. Perubahan ini memperbaiki kualitas gambar secara keseluruhan dan menurun scan waktu sekitar 20 detik untuk satu irisan. Namun, waktu yang dibutuhkan untuk menyelesaikan pada pemeriksaan CT tetap relatif lama.Generasi ketiga scanner memperkenalkan gerakan memutar/memutar, di mana Majelis tabung dan detektor berputar secara konsentris tentang bagian tubuh. Memindai saat itu menurun untuk 1 sampai 10 detik per slice, yang membuat scan lebih mudah bagi pasien dan membantu untuk mengurangi gerakan artefak. Advencements in teknologi komputer juga menurun saat rekonstruksi gambar, mengakibatkan pengurangan substansial dalam ujian waktu.Perubahan besar berikutnya dalam desain CT scanner, generasi keempat, memperkenalkan gerakan memutar hanya, di mana tabung diputar tentang pasien, tetapi detektor yang stasioner di tetap postions dalam gantry. Penggunaan stasioner detektor diperlukan jumlah detektor dipasang di scanner yang lebih besar. Generasi keempat scanner cenderung menghasilkan pasien dosis yang lebih tinggi per scan daripada generasi sebelumnya.