| Han Sheng,Peng Xiaodong,Yuan Ke,Yin Rutie,Liao Xiongfei,Wang Xianliang,Zhang Lei,Liu Min,Bi Bin,Chen Yazheng.The effect of bulk electron density on the dose accuracy of treatment planning for postoperative cervical cancer[J].Chinese Journal of Radiological Medicine and Protection,2021,41(2):140-145 |
| The effect of bulk electron density on the dose accuracy of treatment planning for postoperative cervical cancer |
| Received:May 12, 2020 |
| DOI：10.3760/cma.j.issn.0254-5098.2021.02.011 |
| KeyWords:Bulk electron density Cervical cancer Treatment planning Dose calculation |
| FundProject:四川省科技厅社会发展重点研发计划（2020YFS0437）；四川省卫生健康委员会重点课题（18ZD049） |
| Author Name | Affiliation | E-mail | | Han Sheng | Department of Radiation Oncology, Chengdu Second People Hospital, Chengdu 610017, China | | | Peng Xiaodong | Department of Radiation Oncology, Chengdu Second People Hospital, Chengdu 610017, China | | | Yuan Ke | Sichuan Cancer Hospital & Institute, Sichuan Cancer Center, School of Medicine, University of Electronic Science and Technology of China, Radiation Oncology Key Laboratory of Sichuan Province, Chengdu 610041, China | | | Yin Rutie | Department of Gynecology and Obstetrics, West China Second University Hospital, Sichuan University, Key Laboratory of Obstetrics & Gynecologic and Pediatric Diseases and Birth Defects of Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu 610041, China | | | Liao Xiongfei | Sichuan Cancer Hospital & Institute, Sichuan Cancer Center, School of Medicine, University of Electronic Science and Technology of China, Radiation Oncology Key Laboratory of Sichuan Province, Chengdu 610041, China | | | Wang Xianliang | Sichuan Cancer Hospital & Institute, Sichuan Cancer Center, School of Medicine, University of Electronic Science and Technology of China, Radiation Oncology Key Laboratory of Sichuan Province, Chengdu 610041, China | | | Zhang Lei | Department of Radiation Oncology, Chengdu Second People Hospital, Chengdu 610017, China | | | Liu Min | Sichuan Cancer Hospital & Institute, Sichuan Cancer Center, School of Medicine, University of Electronic Science and Technology of China, Radiation Oncology Key Laboratory of Sichuan Province, Chengdu 610041, China | | | Bi Bin | Sichuan Cancer Hospital & Institute, Sichuan Cancer Center, School of Medicine, University of Electronic Science and Technology of China, Radiation Oncology Key Laboratory of Sichuan Province, Chengdu 610041, China | | | Chen Yazheng | Department of Gynecology and Obstetrics, West China Second University Hospital, Sichuan University, Key Laboratory of Obstetrics & Gynecologic and Pediatric Diseases and Birth Defects of Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu 610041, China | cyzufo@163.com |
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| Abstract:: |
| Objective To study the impact on dose accuracy for the treatment planning by manually assigning accurate electron density for CT image-based tumor tissues and organs at risk. Methods Twenty cases of retrospective postoperative cervical cancer radiotherapy plans were selected. The body electron density of the corresponding organs was derived from the ICRU 46 report and assigned in the treatment planning system (Monaco5.11, Sweden), including the bladder, rectum, intestine, kidney, spinal cord, femoral head, and ilium. The original plans were double-arc volumetric modulated arc therapy plan (360° VMAT), using Monte Carlo algorithm, the calculation grid was 0.3 cm×0.3 cm×0.3 cm, and the minimum subfield width was 0.6 cm. Keep the original plan fluence unchanged and recalculate the dose to generate a new plan. The two-dimensional dose distribution and dose-volume histogram (DVH) were used to compare the differences between the two plans. The difference was compared between the two group plans by using the dosimetry parameters and DVH two dimension curve. Results For the planning of assigning bulk electron density (PlanRED), the deviation of the patient's target dose parameters and the original plan (Planref) was <2%, and the average deviation of all target regions D2, D98, Dmean was < 0.7%, only 2 of the 180 data were between 2% and 3%. The average deviation of V20, V30, D1 cm3, Dmean of the bladder, rectum, and small intestine, the original Planref was less than 0.6%, and 4 out of 240 data had values > 2%. PlanRED's average hop count was 0.9% higher than Planref, and the total number of subfields remains unchanged. The planned dose generated by manually assigning the electron density in PlanRED was higher than that in Planref, but met the clinical requirements. The two-dimensional curves of the DVH diagram for targets and OARs almost completely overlapped, and there was no obvious difference in the dose distribution diagram of the same cross section. The statistical result of all parameters showed that the difference in planned dose parameters between the two groups was not statistically significant(P>0.05). Conclusions The overall deviation of dose accuracy between PlanRED and Planref is <2%, which meets the clinical requirements and provides a reference for realizing MRI-only treatment planning. |
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