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. 2023 Jun 20;43(6):1035-1040.
doi: 10.12122/j.issn.1673-4254.2023.06.21.

[Quantitative evaluation of radiotherapy plan in precise external beam radiotherapy process management for cervical cancer]

[Article in Chinese]
Y Guo  1   2 , T Li  1   2   3 , X Yang  1 , Z Qi  1 , L Chen  1 , S Huang  1
Affiliations

[Quantitative evaluation of radiotherapy plan in precise external beam radiotherapy process management for cervical cancer]

[Article in Chinese]
Y Guo et al. Nan Fang Yi Ke Da Xue Xue Bao. .

Abstract
in English, Chinese

Objective: To identify the problems in clinical radiotherapy planning for cervical cancer through quantitative evaluation of the radiotherapy plans to improve the quality of the plans and the radiotherapy process.

Methods: We selected the clinically approved and administered radiotherapy plans for 227 cervical cancer patients undergoing external radiotherapy at Sun Yat-sen University Cancer Center from May, 2019 to January, 2022. These plans were transferred from the treatment planning system to the Plan IQTM workstation. The plan quality metrics were determined based on the guidelines of ICRU83 report, the GEC-ESTRO Working Group, and the clinical requirements of our center and were approved by a senior clinician. The problems in the radiotherapy plans were summarized and documented, and those with low scores were re-planned and the differences were analyzed.

Results: We identified several problems in the 277 plans by quantitative evaluation. Inappropriate target volume selection (with scores < 60) in terms of GTV, PGTV (CI) and PGTV (V66 Gy) was found in 10.6%, 65.2%, and 1% of the plans, respectively; and the PGTV (CI), GTV, and PCTV (D98%, HI) had a score of 0 in 0.4%, 10.1%, 0.4%, 0.4% of the plans, respectively. The problems in the organs at risk (OARs) involved mainly the intestines (the rectum, small intestine, and colon), found in 20.7% of the plans, and in occasional cases, the rectum, small intestine, colon, kidney, and the femoral head had a score of 0. Senior planners showed significantly better performance than junior planners in PGTV (V60 Gy, D98%), PCTV (CI), and CTV (D98%) (P≤0.046) especially in terms of spinal cord and small intestine protection (P≤0.034). The bowel (the rectum, small intestine and colon) dose was significantly lower in the prone plans than supine plans (P < 0.05), and targets coverage all met clinical requirements. Twenty radiotherapy plans with low scores were selected for re-planning. The re-planned plans had significantly higher GTV (Dmin) and PTV (V45 Gy, D98%) (P < 0.05) with significantly reduced doses of the small intestines (V40 Gy vs V30 Gy), the colon (V40 Gy vs V30 Gy), and the bladder (D35%) (P < 0.05).

Conclusion: Quantitative evaluation of the radiotherapy plans can not only improve the quality of radiotherapy plan, but also facilitate risk management of the radiotherapy process.

目的: 通过对宫颈癌外照射放射治疗计划的量化评估，探究放疗计划中存在的问题以指导临床，降低出错几率，提高放疗计划质量，完善放疗流程。

方法: 选取2019年5月~2022年1月在中山大学肿瘤防治中心进行放射治疗的227例宫颈癌患者，将经临床批准且实施的放疗计划通过计划系统至Plan IQTM工作站。根据ICRU83号报告、GEC-ESTRO工作组的推荐指南及本中心临床要求制定评估指标，经高资历临床医生批准后对计划进行量化评估。总结记录放疗计划中存在的问题，同时，对评分较低的计划重新再计划，分析再计划前后的差异性。

结果: 通过对277例宫颈癌放疗计划分析得出：（1）靶区得分不及格主要是大体肿瘤GTV、计划靶区PGTV（CI、V66Gy），分别为10.6%、65.2%、1%。得分0的有：计划靶区PGTV（CI）、大体肿瘤GTV、计划靶区PCTV（D98%、HI），分别为0.4%、10.1%、0.4%、0.4%。OARs中不及格的主要是肠道（直肠、小肠、结肠），比例≥20.7%。且直肠、小肠、结肠、肾、股骨头存在得分为0的情况；（2）资深剂量师在PGTV（V60 Gy、D98%）、PCTV（CI）、CTV（D98%）上优于初级剂量师（P≤0.046），且在脊髓和小肠的保护方面一致性优于初级剂量师（P≤0.034）；（3）俯卧位组计划在满足靶区要求的情况下，肠道的剂量明显低于仰卧位组计划（P < 0.05）。选择得分低的20例放疗计划进行再计划，结果再计划靶区的GTV（Dmin）、PTV（V45 Gy、D98%）高于原计划（P < 0.05）。在OARs中，小肠（V40 Gy和V30 Gy）、结肠（V40 Gy和V30 Gy）、膀胱（D35%）的剂量均明显低于原计划（P < 0.05）。

结论: 放疗计划的量化评估在提高放疗计划质量的同时，可实现放疗计划质量及放疗流程的风险管理。

Keywords: cervical cancer; external beam radiotherapy; plan quality; quantitative evaluation; replanning.

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Figures

图 1
图 1
患者计划中各单项指标分布情况 Distribution of indicators in plans (the dotted lines represent score 100 and 60, respectively). A: Normalized targets score. B: Normalized OARs scores. HI: Homogeneity index; CI: Conformity index.
See this image and copyright information in PMC

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