| MA Pan,DAI Jian-rong,SH Jie.MLC routine QA with a 2D diode array[J].Chinese Journal of Radiological Medicine and Protection,2009,29(2):217-220 |
| MLC routine QA with a 2D diode array |
| Received:April 01, 2008 |
| DOI：10.3760/cma.j.issn.0254-5098.2009.02.037 |
| KeyWords:Two-dimension diode array Multileaf collimator Positioning error Quality assurance |
| FundProject: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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| Abstract:: |
| 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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