Oinam Arun S, Singh Lakhwant, Sharma S C, Goswami Pradeep
Department of Radiotherapy, PGIMER, Chandigarh, India.
J Med Phys. 2009 Jul;34(3):153-60. doi: 10.4103/0971-6203.54850.
2D array of ionization chambers can be used for both absolute and relative dose verification of patient-specific intensity-modulated radiotherapy (IMRT) quality assurance. After an analysis of the dose linearity and spatial resolution of this 2D array (I'mRT MatriXX), the signal sampling time of 200 ms was selected for data acquisition. Multiple-sequence acquisitions at the nearest 4 positions with the shift of half of the distance between the centers of two adjacent ion chambers increase the spatial resolution up to four times when used with this I'mRT MatriXX. IMRT verification of head-and-neck case, which requires a large area for dosimetric verification, can be done with limited size of 24x24 cm(2), depending on the user requirements. It is found that the convolution method can also be used to improve the IMRT dose verification with the same parameters of the passing criteria significantly, viz., up to 99.87% agreement, by smoothening the treatment planning system profile.
二维电离室阵列可用于患者特异性调强放射治疗（IMRT）质量保证的绝对剂量和相对剂量验证。在分析了该二维阵列（I'mRT MatriXX）的剂量线性和空间分辨率后，选择200毫秒的信号采样时间进行数据采集。当与该I'mRT MatriXX一起使用时，在最近的4个位置进行多序列采集，相邻两个电离室中心之间距离的一半的偏移可将空间分辨率提高四倍。头颈部病例的IMRT验证需要大面积的剂量验证，根据用户需求，可在24x24 cm²的有限尺寸下完成。研究发现，通过平滑治疗计划系统轮廓，卷积方法也可用于以相同的通过标准参数显著改善IMRT剂量验证，即一致性高达99.87%。
