摘要
目的研究用热释光剂量片（TLD）测量在光子射线放射治疗中患者剂量的方法，验证治疗计划系统（TPS）计算的剂量与TLD测量剂量进行比较，相对偏差为±5％。方法用^60Co γ射线，6MV X射线和固体模体，开展热释光剂量片的分散性、重复性、衰退、非线性剂量响应实验。根据临床治疗需要，选择不同条件，研究剂量随照射野、源到皮肤距离、机器角度、能量响应、楔形角度、挡块和托盘等变化的影响，分别求出校准因子。用仿真人模体和热释光剂量片，验证模体的骨盆，头和颈等治疗部位的剂量；然后用热释光剂量片测量6MV X射线放疗患者的骨盆、头和颈等356个剂量点的剂量。结果TLD片放在骨盆前面、左和右侧部位，加楔形和不加楔形角度。以及颈与下巴连接的左侧和右侧部位，带面具和不带面具，这些治疗部位照射后，所有TLD测量值与TPS值的相对偏差均在±3．7％以内。结论用热释光片验证放射治疗中患者剂量的方法准确可靠，经济适用。该方法作为质量保证手段之一，得到了国际原子能机构（IAEA）的认可，并且可以在开展放射治疗的医院中推广使用。
Objective To explore the measurement method of the treatment dose of the patient with TLD chip for photon beam in radiotherapy, and validate the treatment dose by comparing with the treatment plan system （ TPS）, in order to decide if the relative deviation is within ±5 % between two methods. Methods The experiment of the dispersion, the reproducibility, the fading and non-linearity dose response with TLD in ^60Co γ and 6 MV beams were carried out. According to need of clinic treatment different conditions were choose to observe the dose changes with the field size, distance of source to skin, angle of incidence, energy response, wedge angle, block and tray using ionization chamber and water phantom. The TLDs were placed on the surface of solid phantom and the correction factors were obtained. Doses of the pelvis, head and neck were verified with the Alderson phantom and TLD. TLD doses of the pelvis, head and neck on 356 points of the patients that performed radiotherapy were measured. Results If the TLDs were irradiated on the points on the Alderson phantom, such as AP, RL and LL of the pelvis, with and without wedges, RL and LL junction of the neck and chin, with and without a mask, the relative deviation of doses is within ±3.7% between TLD and TPS. Conclusions The TLD method is reliable for measuring the exposure doses of the patient performed radiotherapy. It is also accuracy and economical, and it is approved by IAEA as a method for quality assurance, so that it is deserve to use the TLD measurement for patient performed radiotherapy.
出处
《中华放射医学与防护杂志》
CAS
CSCD
北大核心
2007年第4期380-384,共5页
Chinese Journal of Radiological Medicine and Protection
基金
IAEA资助项目（13114/Ro）
