Safari M J, Wong J H D, Ng K H, Jong W L, Cutajar D L, Rosenfeld A B
Department of Biomedical Imaging, Faculty of Medicine, University of Malaya, Kuala Lumpur 50603, Malaysia and University of Malaya Research Imaging Centre, Faculty of Medicine, University of Malaya, Kuala Lumpur 50603, Malaysia.
Clinical Oncology Unit, Faculty of Medicine, University of Malaya, Kuala Lumpur 50603, Malaysia.
Med Phys. 2015 May;42(5):2550-8. doi: 10.1118/1.4918576.
The MOSkin is a MOSFET detector designed especially for skin dose measurements. This detector has been characterized for various factors affecting its response for megavoltage photon beams and has been used for patient dose measurements during radiotherapy procedures. However, the characteristics of this detector in kilovoltage photon beams and low dose ranges have not been studied. The purpose of this study was to characterize the MOSkin detector to determine its suitability for in vivo entrance skin dose measurements during interventional radiology procedures.
The calibration and reproducibility of the MOSkin detector and its dependency on different radiation beam qualities were carried out using RQR standard radiation qualities in free-in-air geometry. Studies of the other characterization parameters, such as the dose linearity and dependency on exposure angle, field size, frame rate, depth-dose, and source-to-surface distance (SSD), were carried out using a solid water phantom under a clinical x-ray unit.
The MOSkin detector showed good reproducibility (94%) and dose linearity (99%) for the dose range of 2 to 213 cGy. The sensitivity did not significantly change with the variation of SSD (± 1%), field size (± 1%), frame rate (± 3%), or beam energy (± 5%). The detector angular dependence was within ± 5% over 360° and the dose recorded by the MOSkin detector in different depths of a solid water phantom was in good agreement with the Markus parallel plate ionization chamber to within ± 3%.
The MOSkin detector proved to be reliable when exposed to different field sizes, SSDs, depths in solid water, dose rates, frame rates, and radiation incident angles within a clinical x-ray beam. The MOSkin detector with water equivalent depth equal to 0.07 mm is a suitable detector for in vivo skin dosimetry during interventional radiology procedures.
MOSkin是一种专门设计用于皮肤剂量测量的MOSFET探测器。该探测器已针对影响其对兆伏级光子束响应的各种因素进行了特性表征，并已用于放射治疗过程中的患者剂量测量。然而，该探测器在千伏级光子束和低剂量范围内的特性尚未得到研究。本研究的目的是对MOSkin探测器进行特性表征，以确定其在介入放射学程序中进行体内入射皮肤剂量测量的适用性。
在自由空气中使用RQR标准辐射质量对MOSkin探测器进行校准和再现性研究，以及研究其对不同辐射束质量的依赖性。使用临床X射线机下的固体水模体对其他特性参数进行研究，如剂量线性以及对曝光角度、射野大小、帧率、深度剂量和源皮距（SSD）的依赖性。
对于2至213 cGy的剂量范围，MOSkin探测器显示出良好的再现性（94%）和剂量线性（99%）。灵敏度不会随着SSD（±1%）、射野大小（±1%）、帧率（±3%）或束能量（±5%）的变化而显著改变。探测器的角度依赖性在360°范围内±5%以内，并且MOSkin探测器在固体水模体不同深度记录的剂量与Markus平行板电离室的记录结果在±3%以内高度吻合。
当暴露于临床X射线束内不同的射野大小、SSD、固体水中的深度、剂量率、帧率和辐射入射角时，MOSkin探测器被证明是可靠的。水等效深度等于0.07 mm的MOSkin探测器是介入放射学程序中进行体内皮肤剂量测定的合适探测器。
