| 马攀,戴建荣,SH Jie.二维半导体探测器阵列在多叶准直器日常质量保证中的应用[J].中华放射医学与防护杂志,2009,29(2):217-220 |
| 二维半导体探测器阵列在多叶准直器日常质量保证中的应用 |
| MLC routine QA with a 2D diode array |
| 投稿时间：2008-04-01 |
| DOI：10.3760/cma.j.issn.0254-5098.2009.02.037 |
| 中文关键词: 半导体探测器阵列 多叶准直器 位置误差 质量保证 |
| 英文关键词:Two-dimension diode array Multileaf collimator Positioning error Quality assurance |
| 基金项目:国家自然科学基金(30570542);吴阶平医学基金会科研基金(WKJ2005-3-006) |
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| 中文摘要: |
| 目的 建立利用半导体探测器阵列检测多叶准直器(MLC)叶片定位误差的方法,用于MLC的日常质量保证。方法 在MapCheck半导体探测器阵列上,相邻行探测器是错开半个探测器间距分布的。针对这种分布特点,设计了台阶式叶片位置模式,代替胶片测量常用的篱笆式(picket fence)叶片位置模式,作为叶片位置参考模式。在参考模式的基础上,人为引入不同大小的叶片位置误差,得到一组新的叶片位置模式——叶片位置校准模式。依次照射参考模式和校准模式,得到每一个探测器测量剂量与叶片位置误差的关系曲线。该曲线作为测量叶片位置误差的校准曲线。在进行MLC日常质量保证时,只需定期照射叶片位置参考模式,就可得到定量的叶片位置误差。结果 新方法在一个配置40对MLC的加速器上进行了测试(Elekta Precise)。篱笆式叶片位置模式一次检测160个叶片位置,而台阶式叶片位置模式一次检测240个位置, 检测效率提高50%;对于同样的1mm叶片误差,前后两种模式的剂量变化分别是17%和25%,因此测量灵敏度提高8%。结论 建立了一种新的定量的MLC日常QA方法。通过重新设计叶片位置模式,新方法提高了实施效率和测量灵敏度。 |
| 英文摘要: |
| Objective To design leaf patterns for Multileaf Collimator(MLC) routine quality assurance(QA) with a 2D diode array.Methods According to the detector distribution characteristic of the 2D diode array and basing on the "picket fence" pattern, design the"stepwise"pattern. For each diode involving MLC QA, a calibration curve of relative output versus leaf positioning error was measured through delivering a set of patterns with different intentionally introduced positioning errors. When this proposed technique was delivered, the referenced patterns were exposed, and the calibration curves were used as a mean to quantitative determination of the leaf possible positioning errors through the detector readings. Results Compared with the "picket fence" pattern, the "stepwise" pattern not only had a high detecting efficiency, but also increased the dosimetric sensitivity to leaf positioning error. A 1 mm leaf positioning error corresponds to a dose variation of 25% for the "stepwise" pattern, while for the "picket fence" pattern the same positioning error just causes a 17% dose variation. Conclusion The new "stepwise" pattern is more efficient to be carried out, and more sensitive to sub-millimeter changes of leaf positioning. |
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