López-Tarjuelo Juan, Bouché-Babiloni Ana, Morillo-Macías Virginia, Santos-Serra Agustín, Ferrer-Albiach Carlos
Servicio de Radiofísica y Protección Radiológica, Consorcio Hospitalario Provincial de Castellón, Avda. Dr. Clará, 19, Castellón de la Plana 12002, Spain.
Servicio de Oncología Radioterápica, Consorcio Hospitalario Provincial de Castellón, Avda. Dr. Clará, 19, Castellón de la Plana 12002, Spain.
Rep Pract Oncol Radiother. 2017 Jan-Feb;22(1):55-67. doi: 10.1016/j.rpor.2016.09.009. Epub 2016 Oct 19.
To estimate angular response deviation of MOSFETs in the realm of intraoperative electron radiotherapy (IOERT), review their energy dependence, and propose unambiguous names for detector rotations.
MOSFETs have been used in IOERT. Movement of the detector, namely rotations, can spoil results.
We propose yaw, pitch, and roll to name the three possible rotations in space, as these unequivocally name aircraft rotations. Reinforced mobile MOSFETs (model TN-502RDM-H) and an Elekta Precise linear accelerator were used. Two detectors were placed in air for the angular response study and the whole set of five detectors was calibrated as usual to evaluate energy dependence.
The maximum readout was obtained with a roll of 90° and 4 MeV. With regard to pitch movement, a substantial drop in readout was achieved at 90°. Significant overresponse was measured at 315° with 4 MeV and at 45° with 15 MeV. Energy response is not different for the following groups of energies: 4, 6, and 9 MeV; and 12 MeV, 15 MeV, and 18 MeV.
Our proposal to name MOSFET rotations solves the problem of defining sensor orientations. Angular response could explain lower than expected results when the tip of the detector is lifted due to inadvertent movements. MOSFETs energy response is independent of several energies and differs by a maximum of 3.4% when dependent. This can limit dosimetry errors and makes it possible to calibrate the detectors only once for each group of energies, which saves time and optimizes lifespan of MOSFETs.
评估金属氧化物半导体场效应晶体管（MOSFET）在术中电子放射治疗（IOERT）领域的角响应偏差，研究其能量依赖性，并为探测器旋转提出明确的命名。
MOSFET已用于IOERT。探测器的移动，即旋转，可能会影响结果。
我们建议用偏航、俯仰和滚转来命名空间中三种可能的旋转，因为这些名称明确地用于飞机旋转。使用了增强型移动MOSFET（型号TN - 502RDM - H）和医科达Precise直线加速器。将两个探测器置于空气中进行角响应研究，并像往常一样对整套五个探测器进行校准以评估能量依赖性。
在滚转90°和4兆电子伏特时获得最大读数。关于俯仰移动，在90°时读数大幅下降。在4兆电子伏特315°和15兆电子伏特45°时测量到明显的过度响应。以下几组能量的能量响应没有差异：4、6和9兆电子伏特；以及12兆电子伏特、15兆电子伏特和18兆电子伏特。
我们对MOSFET旋转命名的提议解决了定义传感器方向的问题。角响应可以解释由于意外移动导致探测器尖端抬起时结果低于预期的情况。MOSFET的能量响应与几种能量无关，相关时最大差异为3.4%。这可以限制剂量测定误差，并使得每组能量只需对探测器校准一次，从而节省时间并优化MOSFET的使用寿命。
