二维电离室矩阵在鼻咽癌调强适形放射治疗相对剂量验证中的应用

目的 利用二维电离室矩阵(matrixx)对鼻咽癌调强适形放射治疗(IMRT)计划进行相对剂量验证。方法 将30例鼻咽癌患者的IMRT计划移植到matrixx验证模型,生成验证计划。对二维电离室矩阵按验证计划进行实际机架角度下照射,将测得的平面剂量分布与验证计划中相同平面剂量分布分别输入到ominiPro-IMRT软件,依次进行验证计划与实测剖面图分析、验证计划与实测等剂量曲线分析,并用gamma分析量化。gamma值γ(rm)]≤1的通过点,大于90%时表示患者IMRT计划通过。结果 30例患者的IMRT计划有27例患者计划通过点大于90%;有3例患者通过点分别为85.89%、86.56%、80.53%,经修正IMRT计划后,亦获得通过。结论 二维电离室矩阵可以作为IMRT计划平面剂量分布验证的工具,且使用简捷、方便。应用matrixx进行IMRT计划相对剂量验证的方法,可保证IMRT计划实施的准确性。

The application of two-dimensional ionization chamber array for relative dosimetric verification of intensity-modulated radiation therapy in nasoparyngeal carcinoma

Objective Use two-dimensional ionization chamber array(matrixx)for relative dosimetry verification of intensity modulated radiation therapy(IMRT)nasoparyngeal carcinoma(NPC).Methods Thirty patients were treated with IMRT,used theirs IMRT plans transferred to verification of matrixx model,then generated quality assurance(QA)plane in therapy plan system (TPS).According to QA plan treat for twodimensional ionization chamber array with an actual gantry angle,and then output the measured plane dose distribution and identical plan dose distribution to ominiPro-IMRT software.Afterwards carry out QA plan and measured sectional image analysis,QA plan and measured isodose curve analysis by turns,and gamma analysis quantization.The gamma valueγ(rm)]of the measurement point,γ(rm)]≤1 demonstrate point calculation passes,the passes point more than 90%indicate that QA plan passes for relative dosimetric verification.Results Thirty patients IMRT plans have twenty-seven plans calculation passes,the other three patients'passed point are 85.89%,86.56%,80.53%,which means the calculation fails.The pass rate is 90%.According to adjust therapy plan,theirs plan passed.Conclusion Two-dimensional ionization chamber array is easy and convenient to apply,which can be used as a tool for plane dose distribution verification of IMRT.It ensure that plan accuracy,which use a method of relative dosimetric verification for patients treated with intensity modulated radiation therapy.