Fricker Katherine, Thompson Christine, Meyer Juergen
Department of Physics and Astronomy, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand.
Australas Phys Eng Sci Med. 2013 Sep;36(3):269-77. doi: 10.1007/s13246-013-0208-y. Epub 2013 Jun 22.
To assess the suitability of EBT2 and XRQA2 Gafchromic film for measuring low doses in the periphery of treatment fields, and to measure the accumulative concomitant dose to the contralateral testis resulting from CT imaging, pre-treatment imaging (CBCT) and seminoma radiotherapy with and without gonadal shielding. Superficial peripheral dose measurements made using EBT2 Gafchromic film on the surface of water equivalent material were compared to measurements made with an ionisation chamber in a water phantom to evaluate the suitability and accuracy of the film dosimeter for such measurements. Similarly, XRQA2 was used to measure surface doses within a kilovoltage beam and compared with ionisation chamber measurements. Gafchromic film was used to measure CT, CBCT and seminoma treatment related testicular doses on an anthropomorphic phantom. Doses were assessed for two clinical plans, both with and without gonadal shielding. Testicular doses resulting from the treatment of up to 0.83 ± 0.17 Gy were measured per treatment. Additional doses of up to 0.49 ± 0.01 and 2.35 ± 0.05 cGy were measured per CBCT and CT image, respectively. Reductions in the testicular dose in the order of 10, 36 and 78% were observed when gonadal shielding was fitted for treatment, CT and CBCT imaging, respectively. Gafchromic film was found to be suitable for measuring dose in the periphery of treatment fields. The dose to the testis should be limited to minimise the risk of radiation related side effects. This can be achieved by using appropriate gonadal shielding, irrespective of the treatment fields employed.
评估EBT2和XRQA2型放射变色薄膜用于测量治疗野周边低剂量的适用性，并测量CT成像、治疗前成像（CBCT）以及有无性腺屏蔽的精原细胞瘤放疗对侧睾丸的累积伴随剂量。将使用EBT2型放射变色薄膜在水等效材料表面进行的浅表周边剂量测量与在水体模中使用电离室进行的测量相比较，以评估该薄膜剂量仪用于此类测量的适用性和准确性。同样，XRQA2用于测量千伏级射束内的表面剂量，并与电离室测量结果进行比较。放射变色薄膜用于在人体模型上测量CT、CBCT和精原细胞瘤治疗相关的睾丸剂量。对两个临床计划评估剂量，包括有无性腺屏蔽的情况。每次治疗测量得到的睾丸剂量高达0.83±0.17 Gy。每次CBCT和CT图像分别测量得到的额外剂量高达0.49±0.01 cGy和2.35±0.05 cGy。当分别针对治疗、CT和CBCT成像安装性腺屏蔽时，观察到睾丸剂量分别降低了10%、36%和78%。发现放射变色薄膜适用于测量治疗野周边的剂量。应限制对睾丸的剂量，以尽量降低辐射相关副作用的风险。无论采用何种治疗野，这都可以通过使用适当的性腺屏蔽来实现。
