Lah J, Kim D, Park S
Myongji Hospital, Kwandong University College of Medicine, Korea.
The Catholic University of Korea, Korea.
Med Phys. 2012 Jun;39(6Part11):3735. doi: 10.1118/1.4735197.
To evaluate the suitability of the GD-301 glass dosimeter for use in in vivo dose verification in proton therapy.
The glass dosimeter was analyzed for its dosimetric characteristic in proton beam. Dosimeters were calibrated in a water phantom using a stair-like holder specially designed for this study. To determine the accuracy of the glass dosimeter in proton dose measurements, we compared the glass dosimeter and TLD dose measurements of plan delivery using a cylindrical phantom. We investigated the feasibility of the glass dosimeter for the measurement of dose distributions near the superficial region for proton therapy plans with a varying separation between the target volume and the surface of 6 patients.
Uniformity was within 1.5%. The dose-response has a good linear. Dose-rate, fading, and energy dependence were found to be within 3%. The beam profile measured using the glass dosimeter was in good agreement with the profile obtained from the ionization chamber. Depth-dose distributions in non-modulated and modulated proton beams obtained with the glass dosimeter were estimated to be within 3%, which was lower than those with the ionization chamber. In the phantom study, the difference of isocenter dose between the delivery dose calculated by the Eclipse and that of the measured by the glass dosimeter was within 5%. In vivo dosimetry of patients, given the results of the glass dosimeter and TLD measurements, calculated doses on the surface of the patient are typically overestimated between 4% and 16%.
As such, it is recommended that bolus be added for these clinical cases. We also believe that the glass dosimeter has considerable potential to be used for in vivo patient proton dosimetry.
评估GD - 301玻璃剂量仪在质子治疗体内剂量验证中的适用性。
分析玻璃剂量仪在质子束中的剂量学特性。使用专门为本研究设计的阶梯状支架在水模体中对剂量仪进行校准。为确定玻璃剂量仪在质子剂量测量中的准确性，我们使用圆柱形模体比较了玻璃剂量仪和热释光剂量仪（TLD）对计划照射剂量的测量结果。我们研究了玻璃剂量仪用于测量6例患者靶区体积与体表间距不同的质子治疗计划浅表区域附近剂量分布的可行性。
均匀性在1.5%以内。剂量响应具有良好的线性。发现剂量率、衰退和能量依赖性在3%以内。使用玻璃剂量仪测量的射野轮廓与电离室获得的轮廓吻合良好。用玻璃剂量仪获得的非调制和调制质子束的深度剂量分布估计在3%以内，低于电离室测量的结果。在模体研究中，Eclipse计算的照射剂量与玻璃剂量仪测量的等中心剂量之间的差异在5%以内。在患者的体内剂量测定中，根据玻璃剂量仪和TLD测量结果，患者体表计算剂量通常高估4%至16%。
因此，建议对这些临床病例添加 bolus。我们还认为玻璃剂量仪在用于患者体内质子剂量测定方面具有相当大的潜力。
