Département de Physique, de Génie Physique et d'Optique, Université Laval, Québec, Québec G1K 7P4, Canada.
Phys Med Biol. 2013 Jul 7;58(13):4439-54. doi: 10.1088/0031-9155/58/13/4439. Epub 2013 Jun 12.
The purposes of this work are to assess the performance of a 2D plastic scintillation detectors array prototype for quality assurance in intensity-modulated radiation therapy (IMRT) and to determine its sensitivity and specificity to positioning errors of one multileaf collimator (MLC) leaf and one MLC leaf bank by applying the principles of signal detection theory. Ten treatment plans (step-and-shoot delivery) and one volumetric modulated arc therapy plan were measured and compared to calculations from two treatment-planning systems (TPSs) and to radiochromic films. The averages gamma passing rates per beam found for the step-and-shoot plans were 95.8% for the criteria (3%, 2 mm), 97.8% for the criteria (4%, 2 mm), and 98.1% for the criteria (3%, 3 mm) when measurements were compared to TPS calculations. The receiver operating characteristic curves for the one leaf errors and one leaf bank errors were determined from simulations (theoretical upper limits) and measurements. This work concludes that arrays of plastic scintillation detectors could be used for IMRT quality assurance in clinics. The use of signal detection theory could improve the quality of dosimetric verifications in radiation therapy by providing optimal discrimination criteria for the detection of different classes of errors.
本工作旨在评估二维塑料闪烁探测器阵列原型在强度调制放射治疗 (IMRT) 质量保证中的性能，并应用信号检测理论的原理，确定其对一个多叶准直器 (MLC) 叶片和一个 MLC 叶片组位置误差的灵敏度和特异性。对十个治疗计划（步进式传输）和一个容积调强弧形治疗计划进行了测量，并与两个治疗计划系统 (TPS) 的计算值和放射色胶片进行了比较。对于步进式计划，当测量值与 TPS 计算值进行比较时，符合（3%，2mm）和（4%，2mm）标准的平均伽马通过率分别为 95.8%和 97.8%，符合（3%，3mm）标准的平均伽马通过率为 98.1%。通过模拟（理论上限）和测量确定了单个叶片误差和单个叶片组误差的受试者工作特征曲线。本工作得出结论，塑料闪烁探测器阵列可用于临床中的 IMRT 质量保证。通过为检测不同类别的误差提供最佳的判别标准，信号检测理论的应用可以提高放射治疗中的剂量验证质量。
