Application of commercial MOSFET detectors for in vivo dosimetry in the therapeutic x-ray range from 80 kV to 250 W
Application of commercial MOSFET detectors for in vivo dosimetry in the therapeutic x-ray range from 80 kV to 250 W
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DOI：
10.1088/0031-9155/50/2/008
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发表时间：
2005-01-21
影响因子：
3.5
通讯作者：
Georg, D
中科院分区：
文献类型：
--
作者：
Ehringfeld, C;Schmid, S;Georg, D
本研究的目的是研究用于 kV X 射线范围内体内剂量测定的 MOSFET 探测器的剂量测定特性（能量依赖性、线性、衰落、再现性等）。还报告了使用 Alderson 体模进行的临床前研究和临床实践中 MOSFET 体内剂量测定的经验。所有测量均使用 Gulmay D3300 kV 装置和 TN-502RDI MOSFET 探测器进行。为了确定校正因子，使用了不同的实体模型和校准的农夫型室。对于所有能量，MOSFET 信号与 0.2 至 2 Gy 范围内的施加剂量呈线性关系。由于衰落，建议在照射后的前 15 分钟内读取 MOSFET 信号。对于照射和读出之间的较长时间间隔，衰落可能因探测器而有很大变化。在 22 至 40 摄氏度之间的温度范围内，检测器信号的温度依赖性很小（0.3% 摄氏度(-1)）。测量信号随光束入射的变化达5%，在临床应用中应予以考虑。最后，对于入口剂量测量能量相关的校准因子，应用了场大小和辐照电缆长度的校正因子。所有测量的总体准确度取决于作为所施加剂量的函数的再现性。临床前期间呢？ Vivo 研究中，MOSFET 和 TLD 测量值之间的一致性在 3% 以内。 MOSFET 测量结果确定了剂量测定特性以及临床应用，表明 MOSFET 探测器适用于 kV 范围内的体内剂量测定。然而，需要考虑并纠正一些与能量相关的剂量测定效应。由于低剂量水平下的再现性影响，只有当施加的剂量等于或大于 2 Gy 时才可能进行精确的体内测量。
The purpose of this study was to investigate the dosimetric characteristics (energy dependence, linearity, fading, reproducibility, etc) of MOSFET detectors for in vivo dosimetry in the kV x-ray range. The experience of MOSFET in vivo dosimetry in a pre-clinical study using the Alderson phantom and in clinical practice is also reported. All measurements were performed with a Gulmay D3300 kV unit and TN-502RDI MOSFET detectors. For the determination of correction factors different solid phantoms and a calibrated Farmer-type chamber were used. The MOSFET signal was linear with applied dose in the range from 0.2 to 2 Gy for all energies. Due to fading it is recommended to read the MOSFET signal during the first 15 min after irradiation. For long time intervals between irradiation and readout the fading can vary largely with the detector. The temperature dependence of the detector signal was small (0.3% degreesC(-1)) in the temperature range between 22 and 40 degreesC. The variation of the measuring signal with beam incidence amounts to 5% and should be considered in clinical applications. Finally, for entrance dose measurements energy -dependent calibration factors, correction factors for field size and irradiated cable length were applied. The overall accuracy, for all measurements, was dominated by reproducibility as a function of applied dose. During the pre-clinical it? vivo study, the agreement between MOSFET and TLD measurements was well within 3%. The results of MOSFET measurements, to determine the dosimetric characteristics as well as clinical applications, showed that MOSFET detectors are suitable for in vivo dosimetry in the kV range. However, some energy -dependent dosimetry effects need to be considered and corrected for. Due to reproducibility effects at low dose levels accurate in vivo measurements are only possible if the applied dose is equal to or larger than 2 Gy.