肺癌125I粒子近距离治疗放射剂量学质量控制与保证的策略研究

  目的  探讨能提高125I粒子植入治疗肺癌增益比的放射物理质量控制和保证(QA/QC)的策略。   方法  确诊的肺癌和肺转移瘤患者287例, 男184例, 女103例, 平均年龄61.9岁。对无阻塞性肺不张非小细胞肺癌(non obstructive atelectasis non-small cell lung cancer, NOA-NSCLC)亚组和肺转移瘤组常规采用CT靶区定位, 对CT难以确定肿瘤靶区的中央型阻塞性肺不张非小细胞肺癌(the central obstructive atelectasis non-small cell lung cancer, COA-NSCLC)亚组采用符合线路单光子发射型计算机断层显像仪(single photon emission computerized tomography, SPECT)协助定位; 应用体积剂量直方图(dose volume histograms, DVH)等评估TPS的质量并优化; 影像引导粒子植入中必须进行实时的位置校正。对无法单独经皮CT引导植入粒子的晚期中央型病灶结构复杂的肺癌亚组(central lung cancer, C-LC亚组), 要同期采用纤维支气管镜(flexible fiber optic bronchoscopy, FFB)直视下联合CT引导下经皮穿刺植入; 植入后必须进行剂量学等验证。   结果  137例的NOA-NSCLC亚组的计划靶区(planning target volume, PTV)外危及器官(organs at risk, OAR)心、肺及脊髓的平均照射剂量明显低于正常组织耐受剂量。NOA-NSCLC亚组和50例的肺转移瘤组的匹配周缘剂量(matched peripheral dose, MPD)分别达92.1Gy、106.2 Gy。局控总有效率分别为为91.97%(126/137例)和96.00%(48/50例)。1年生存率分别是91.24%(125/137)和83.40%(42/50)。2年生存率分别是50.36%(69/137)和52.30%(26/ 50)。COA-NSCLC亚组的35例和C-LC亚组的65例患者的局部控制总有效率分别为91.43%(32/35)和92.30%(60/65), 1年生存率分别为88.57%(31/35)和80.30%(53/66);无放射性肺损伤或肺纤维化出现。   结论  恰当的放射剂量学QA/QC策略是保证粒子植入疗法提高治疗增益比的必须措施, 尤其是能明显减少放射性肺炎、肺损伤或肺纤维化的发生。 

Radiation physics,quality control,and quality assurance of lung cancer brachytherapy with 125I particles

  Objective  To improve the therapeutic gain ratio from 125I seed implants by investigating the QA/QC strategies used in brachytherapy treatment of lung cancer.   Methods  A total of 287 lung cancer and pulmonary metastases cases were studied. Among which, 184 are male and 103 are female with a mean age of 61.9 years. The NOA-NSCLC subgroup and pulmonary metastases were targeted on conventional CT positioning. Considering that COA-NSCL subgroup on the tumor target area is difficult to determine with CT, the coincidence circuit SPECT was used to assist in positioning. A dose-volume histogram was constructed to evaluate the quality of the TPS and optimization. Corrections on real-time positioning are necessary when using an image-guided implantation. The C-LC should be aligned with the FFB for CT-guided percutaneous puncture implantation. After implantation, dosimetry verification was conducted.   Results  The NOA-NSCLC subgroup, comprising the risk organs such as heart, lung, and spinal column, received an average dose of 137, which was significantly lower than that of normal tissue dose tolerance. The NOA-NSCLC subgroup and lung metastases have matched peripheral dosages of 92.1 and 106.2 Gy with local-control efficiency rates of 91.97% (126/137) and 96.0% (48/50), 1-year survival rates of 91.24% and 83.4% (42/50), and 2-year survival rates of 50.36% (69/137) and 52.3% (26/50), respectively. The 35 COA-NSCL subgroup and 65 lung cancer group have local control efficiency rates of 91.43% (32/35) and 92.3% (60/65) and 1-year survival rates of 88.57% (31/35) and 80.30% (53/66), respectively.   Conclusion  Proper radiation dosimetry as a QA/QC strategy was found to improve particle-implantation therapy gain and greatly reduce the risks of radiation pneumonia and pulmonary fibrosis.