Performance of a direct-detection active matrix flat panel dosimeter (AMFPD) for IMRT measurements.
Performance of a direct-detection active matrix flat panel dosimeter (AMFPD) for IMRT measurements.
复制标题
用于 IMRT 测量的直接检测有源矩阵平板剂量计 (AMFPD) 的性能。
DOI：
10.1118/1.2805993
复制
发表时间：
2007
期刊：
影响因子：
3.8
通讯作者：
Fraass,BenedickA
中科院分区：
文献类型：
--
作者：
Chen,Yu;Moran,JeanM;Roberts,DonaldA;El-Mohri,Youcef;Antonuk,LarryE;Fraass,BenedickA
报道了直接探测有源矩阵平板剂量计（AMFPD）用于调强放射治疗（IMRT）测量的剂量学性能。AMFPD由沉积在玻璃基板上的光电二极管和薄膜晶体管组成，没有覆盖闪烁体屏幕或金属板。该器械在连续采集或荧光透视模式下以0.8帧/秒的速度运行。评估了在光电二极管两端施加的偏置电压对AMFPD响应的影响，因为该参数影响暗信号、滞后贡献和像素灵敏度。此外，AMPFD响应作为剂量，剂量率和能量的函数，在10 cm深度的静态字段进行了评价。在连续采集模式下，AMFPD保持线性剂量响应高达至少1040 cGy。为了获得可靠的IMRT场的积分剂量结果，通过以最高帧速率和适当的反向偏置电压操作系统来最小化延迟对辐射信号的影响。使用AMFPD测量分段MLC和动态MLC IMRT野，并使用可靠胶片剂量测定的标准方法将结果与胶片进行比较。AMFPD和胶片测量值均独立转换为剂量（cGy）。 并计算值作为一致性指数。AMFPD的结果与胶片的结果非常一致。当使用和2 mm的一致距离作为标准时，受试病例的感兴趣区域（定义为剂量大于的区域）平均满足。
The dosimetric performance of a direct‐detection active matrix flat panel dosimeter (AMFPD) is reported for intensity modulated radiation therapy (IMRT) measurements. The AMFPD consists of photodiodes and thin‐film transistors deposited on a glass substrate with no overlying scintillator screen or metal plate. The device is operated at 0.8 frames per second in a continuous acquisition or fluoroscopic mode. The effect of the applied bias voltage across the photodiodes on the response of the AMFPD was evaluated because this parameter affects dark signal, lag contributions, and pixel sensitivity. In addition, the AMPFD response was evaluated as a function of dose, dose rate, and energy, for static fields at 10 cm depth. In continuous acquisition mode, the AMFPD maintained a linear dose response up to at least 1040 cGy. In order to obtain reliable integrated dose results for IMRT fields, the effects of lag on the radiation signal were minimized by operating the system at the highest frame rate and at an appropriate reverse bias voltage. Segmental MLC and dynamic MLC IMRT fields were measured with the AMFPD, and the results were compared to film, using standard methods for reliable film dosimetry. Both AMFPD and film measurements were independently converted to dose in cGy. and values were calculated as indices of agreement. The results from the AMFPD were in excellent agreement with those from film. When of and 2 mm of distance to agreement were used as the criteria, of the region of interest (defined as the region where dose is greater than of ) satisfied on average across the cases that were tested.