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首页> 外文期刊>Medical Physics >Detection of IMRT delivery errors using a quantitative 2D dosimetric verification system.
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Detection of IMRT delivery errors using a quantitative 2D dosimetric verification system.

机译：使用定量2D剂量验证系统检测IMRT传递错误。

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摘要

We investigated the feasibility of detecting intensity modulated radiotherapy delivery errors automatically using a scalar evaluation of two-dimensional (2D) transverse dose measurement of the complete treatment delivery. Techniques using the gamma index and the normalized agreement test (NAT) index were used to parametrize the agreement between measured and computed dose distributions to seven different scalar metrics. Simulated verifications with delivery errors calculated using a commercially available treatment planning system for 9 prostate and 7 paranasal sinus cases were compared to 433 clinical verifications. The NAT index with 5% and 3 mm criteria that included cold areas outside the planning target volume detected the largest percent of delivery errors. Assuming a false positive rate of 5%, it was able to detect 88% of beam energy changes, 94% of a different patient's plan being delivered, 25% of plans with one beam's collimator rotated by 90 degrees, 81% of rotating one beam's gantry angle by 10 degrees, and 100% of omitting the delivery of one beam. However, no instances of changing one beam's monitor unit setting by 10% or shifting the isocenter by 5 mm were detected. Although the phantom shift could not be detected by the small change it made in the dose distribution, our autopositioning algorithm clearly identified the spatial anomaly. Using tighter 3 %/2 mm criteria or combining dose and distance disagreements in an either/or fashion resulted in poorer delivery error detection. The mean value of the 2D gamma index distribution was less sensitive to delivery errors than the other scalar metrics studied. Although we found that scalar metrics do not have sufficient delivery error detection rates to be used as the sole clinical analysis technique, manually examining 2D dose comparison images would result in a near 100% detection rate while performing an ion chamber measurement alone would only detect 54% of these errors.
机译：我们调查了使用二维（2D）横向剂量测量完整治疗的自动评估强度调制放射治疗输送错误的可行性。使用伽玛指数和归一化协议测试（NAT）指数的技术对7种不同标量指标的测量和计算剂量分布之间的一致性进行参数化。使用市售治疗计划系统针对9例前列腺癌和7例鼻旁窦病例计算出的带有传送错误的模拟验证与433个临床验证进行了比较。 NAT指标为5％和3 mm的标准，其中包括计划目标量以外的寒冷区域，检测到最大的交付错误百分比。假设假阳性率为5％，则它能够检测到88％的光束能量变化，94％的不同患者计划正在交付，25％的计划（其中一束光束的准直仪旋转了90度，81％的光束旋转了）。机架角度减少了10度，并且100％省略了一根光束的传送。但是，未检测到将一个光束的监视单位设置更改10％或将等中心线更改5 mm的情况。尽管无法通过剂量分布的微小变化检测到幻像偏移，但我们的自动定位算法可以清楚地识别出空间异常。使用更严格的3％/ 2 mm标准或以或非方式组合剂量和距离差异会导致较差的传送错误检测。二维伽马指数分布的平均值对传递误差的敏感性不如其他研究的标量度量标准高。尽管我们发现标量量度没有足够的传递错误检测率来用作唯一的临床分析技术，但是手动检查2D剂量比较图像将导致接近100％的检测率，而仅执行离子室测量将只能检测到54这些错误的百分比。

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