High-density dental implants and radiotherapy planning: evaluation of effects on dose distribution using pencil beam convolution algorithm and Monte Carlo method.
High-density dental implants and radiotherapy planning: evaluation of effects on dose distribution using pencil beam convolution algorithm and Monte Carlo method.
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DOI：
10.1120/jacmp.v16i5.5612
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发表时间：
2015-09-08
影响因子：
2.1
通讯作者：
Çatli S
中科院分区：
文献类型：
--
作者：
Çatli S
牙科植入物的高原子序数和密度导致在放射治疗中提供准确的剂量分布以及由头颈部肿瘤中的伪影引起的肿瘤和器官轮廓的主要问题。在治疗计划系统中使用的算法的限制和缺陷可能导致剂量计算中的大的误差，并且这可能不利地影响患者的治疗。在本研究中，使用了四种市售牙科种植体：纯钛、钛合金（Ti-6Al-4V）、银汞合金和牙冠。采用笔形束卷积（PBC）算法和6MV光子束蒙特卡罗（Monte Carlo）程序两种方法研究了牙种植体对剂量分布的影响。使用两种算法计算源-皮肤距离（SSD）为100 cm和一个射野的体模中心轴深度剂量。蒙特卡罗方法和Eclipse TPS的结果进行了比较，彼此和以前报道的。在本研究中，由于使用Monte Carlo方法在6 MV下牙科植入物的电子背散射，在牙科植入物前方2 mm距离处的组织中看到剂量增加。Eclipse治疗计划系统（TPS）不能精确计算由义齿引起的后向散射辐射。TPS低估了后向散射剂量，高估了牙种植后的剂量。在这项研究中发现TPS的大误差是由于算法的限制和缺陷。考虑到美国医学物理学家协会放射治疗委员会第65工作组的建议，与蒙特卡罗计算相比，评价了Eclipse TPS的PBC算法的准确性。通过对TPS和Monte Carlo计算结果的比较，验证了Monte Carlo模拟是计算非均匀介质中剂量分布的一种较好方法。PACS编号：87.55.K-
High atomic number and density of dental implants leads to major problems at providing an accurate dose distribution in radiotherapy and contouring tumors and organs caused by the artifact in head and neck tumors. The limits and deficiencies of the algorithms using in the treatment planning systems can lead to large errors in dose calculation, and this may adversely affect the patient's treatment. In the present study, four commercial dental implants were used: pure titanium, titanium alloy (Ti‐6Al‐4V), amalgam, and crown. The effects of dental implants on dose distribution are determined with two methods: pencil beam convolution (PBC) algorithm and Monte Carlo code for 6 MV photon beam. The central axis depth doses were calculated on the phantom for a source–skin distance (SSD) of 100 cm and a field using both of algorithms. The results of Monte Carlo method and Eclipse TPS were compared to each other and to those previously reported. In the present study, dose increases in tissue at a distance of 2 mm in front of the dental implants were seen due to the backscatter of electrons for dental implants at 6 MV using the Monte Carlo method. The Eclipse treatment planning system (TPS) couldn't precisely account for the backscatter radiation caused by the dental prostheses. TPS underestimated the back scatter dose and overestimated the dose after the dental implants. The large errors found for TPS in this study are due to the limits and deficiencies of the algorithms. The accuracy of the PBC algorithm of Eclipse TPS was evaluated in comparison to Monte Carlo calculations in consideration of the recommendations of the American Association of Physicists in Medicine Radiation Therapy Committee Task Group 65. From the comparisons of the TPS and Monte Carlo calculations, it is verified that the Monte Carlo simulation is a good approach to derive the dose distribution in heterogeneous media. PACS numbers: 87.55.K‐
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影响因子：
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