Gafchromic EBT？？ 필름을 이용한 선량분포의 평가
Evaluation of Dose Distribution Using Gafchromic EBT？？ Film
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초록
Gafchromic EBT 필름을 이용하여 정위방사선수술에서 작은 조사야에 대한 선량분포를 측정, 분석하는데 있어 그 유용성을 평가하였다. 조직 등가물질인 water 팬톰의 diode와 아크릴 팬톰내의 EBT 필름을 비교하였으며, 또한 실제 뇌정위방사선수술의 평가를 위해 Gafchromic EBT 필름을 이용하여 인체모형 두부 팬톰내 치료부위 위치를 확인하고 선량을 측정하여 계산값과 비교하였다. diode와 EBT 필름 모두 1.5cm에서 6MV 광자선에 대한 Dmax가 있었으며 팬톰내의 깊은 영역으로 빔이 진행하면 10~20cm서 두 측정방법 모두 2~3% 정도의 오차로 중심에서 벗어나는 경향을 보여주고 있었다. Gafchromic EBT 필름의 실제 조사된 선량분포를 치료계획에서 결정된 선량분포와 비교하면 90% 등선량곡선에서 5% 정도의 차이가 있음을 확인할 수 있었다. 뇌정위방사선수술에서 팬톰을 이용하여 측정한 주어진 목표점에서의 방사선 조사선량이 정확하게 측정된다는 사실을 확인하였으며 또한 정도관리의 한 방법으로도 그 유용성이 확인되었다.
Abstract
Dose evaluation for small field such as stereotactic radiosurgery was performed using Gafchromic EBT film. Every film which irradiated 6MV photon beam was scanned and obtained the optical density(OD) by flat bed scanner after 24 hours of irradiation. This study compared dose from diode in water and Gafchromic EBT film in acrylic phantom to verify the reliability of the film, and to evaluate the SRS in clinical dose distributions from calculation and measurement in the region of virtual target in humanoid and cylindrical phantoms were compared. The Gafchromic EBT film was found to be linear up to 9Gy. The Dmax for 6MV was measured at 1.5cm from the surface by both of diode and the film. As the depth is deeper, the error was measured within 2~3% at 10~20cm depth. Comparing between distribution from calculation and measurement, we found that there is 5% error at 90% isodose line. We found that given dose could be measured accurately by using the phantoms. It was feasible to use the Gafchromic EBT film in quality assurance of SRS.
참고문헌 (10)
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