AJR. American journal of roentgenology · 2009
Spatial resolution and radiation dose of a 64-MDCT scanner compared with published CT urography protocols.
Сравнительное исследованиеСтатьяНазвание и аннотация: Перевод в очереди
Обработка статьи · этапы, ошибки и управление
Загрузка состояния…
Ошибки и ограничения
История · было → стало
Состояние обновляется каждые 5 секунд, пока блок открыт. Процент показывается только там, где известен объём работы. Пауза останавливает продолжение этапа; текущий запрос к источнику может завершиться.
Vrtiska Terri J, Hartman Robert P, Kofler James M, Bruesewitz Michael R, King Bernard F, McCollough Cynthia H
Аннотация
OBJECTIVE: The objective of our study was to compare the spatial resolution and effective dose from 64-MDCT with several published CT urography protocols.
MATERIALS AND METHODS: A phantom containing 1-, 2-, or 4-mm cylindric channels to simulate ureters with 0.25- to 3-mm plugs to simulate ureteral filling defects or ureteral diverticula was imaged using eight helical CT urography protocols. Computed radiography (CR) was also performed. Coronal maximum-intensity-projection images were created and, with the CR image, were evaluated independently by two genitourinary radiologists. Spatial resolution was evaluated by scoring each abnormality as present, visible; or as absent, not visible. Effective dose estimates for 11 CT urography protocols, including the radiographs obtained in the CT urography protocol, were calculated using published Monte Carlo organ dose coefficients.
RESULTS: All ureteral abnormalities detected on CR were detected on the highest-spatial-resolution reconstruction using the evaluated 64-MDCT system. The smallest filling defect identified by both was 0.25 mm. Three 0.25-mm filling defects were not detected using the evaluated 16-MDCT system. The 4-MDCT system protocols showed the poorest performance. The range of effective doses for the evaluated CT urography protocols was 20.1-66.3 mSv. The number of phases, anatomic coverage per phase, and scanning parameters all contributed to this variation in dose.
CONCLUSION: The evaluated 64-MDCT system showed detection accuracy identical to that of CR. Limiting anatomic coverage for specific phases and combining phases can reduce dose for multiphase protocols by up to a factor of 2 relative to early (circa 2000) 4-MDCT.
MATERIALS AND METHODS: A phantom containing 1-, 2-, or 4-mm cylindric channels to simulate ureters with 0.25- to 3-mm plugs to simulate ureteral filling defects or ureteral diverticula was imaged using eight helical CT urography protocols. Computed radiography (CR) was also performed. Coronal maximum-intensity-projection images were created and, with the CR image, were evaluated independently by two genitourinary radiologists. Spatial resolution was evaluated by scoring each abnormality as present, visible; or as absent, not visible. Effective dose estimates for 11 CT urography protocols, including the radiographs obtained in the CT urography protocol, were calculated using published Monte Carlo organ dose coefficients.
RESULTS: All ureteral abnormalities detected on CR were detected on the highest-spatial-resolution reconstruction using the evaluated 64-MDCT system. The smallest filling defect identified by both was 0.25 mm. Three 0.25-mm filling defects were not detected using the evaluated 16-MDCT system. The 4-MDCT system protocols showed the poorest performance. The range of effective doses for the evaluated CT urography protocols was 20.1-66.3 mSv. The number of phases, anatomic coverage per phase, and scanning parameters all contributed to this variation in dose.
CONCLUSION: The evaluated 64-MDCT system showed detection accuracy identical to that of CR. Limiting anatomic coverage for specific phases and combining phases can reduce dose for multiphase protocols by up to a factor of 2 relative to early (circa 2000) 4-MDCT.