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Abstract
Objective
To compare the dosimetric difference between various modalities in the radiation treatment for renal retroperitoneal soft tissue sarcoma recurrence or metastasis (RRSTSRM) after radical nephrectomy, and assess the dosimetric advantage on protecting the organs at risk (OARs) in the carbon and proton radiotherapy for the patients with a single kidney.
Methods
A total of 12 patients with RRSTSRM who underwent radical nephrectomy were enrolled in this study. Carbon, proton, and photon radiotherapy were implemented for treatment planning. The prescription dose was fulfilled by simultaneously integrated boosting technique, with giving the planning target volume-1 (PTV-1) 51Gy (RBE) and planning target volume-2 (PTV-2) 60 Gy (RBE). Doses in the patient’s spinal cord, stomach, duodenum, bowel, colon, and contralateral kidney were evaluated. The normal tissue complication probability (NTCP) of the duodenum, bowel, colon, and contralateral kidney was derived under Lyman-Kutcher-Burman (LKB) estimation.
Results
In the carbon plans, the percentage volume of 95% prescription dose (V95%) covering PTV-1 (PTV-2) was 95.93% ± 3.42% (95.61% ± 4.26%). No significant dosimetric difference on the target was obtained between the four radiation modalities (P > .05). The percentage volume of receiving 40 Gy (RBE) [V40Gy (RBE)] in the duodenum could be reduced from 12.94% ± 15.99% in the IMRT plans to 6.36% ± 8.79% (8.44% ± 12.35%) in the carbon (proton) plans (P < .05). The V40Gy (RBE) in the bowel could be reduced from 13.48% ± 13.12% in the IMRT plans to 7.04% ± 9.32% (7.34% ± 9.89%) in the carbon (proton) plans (P < .05). The mean value of NTCP for the duodenum was 0.43 ± 0.47 (0.45 ± 0.48) by using carbon (proton) radiation. The value was 0.05 (0.03) lower than the IMRT plans on average, with a reduction of 0.20 (0.13) for the patients with lesions <5 mm away from the duodenum. The mean doses of the contralateral kidney were 0.28 ± 0.37 Gy (RBE) [0.28 ± 0.40 Gy (RBE)] in the IMCT (IMPT) plans, which was 92.43% (92.43%) lower than the value in the IMRT plans respectively (P < .05).
Conclusion
Compared to the conventional radiation techniques, particle radiotherapy of carbon and proton could significantly spare more OARs in the treatment for RRSTSRM after radical nephrectomy. Patients, especially those whose residuals are close to the duodenum would potentially benefit from the particle radiation therapy for RRSTSRM on the decrease in radiation-related side-effect.
Disclosure statement
No potential conflict of interest was reported by the authors.
Additional information
Funding
Notes on contributors
Xue Ming
Xue Ming is a Medical Physicist in Medical Physics Department at Shanghai Proton and Heavy Ion Center, Shanghai, China.
Weiwei Wang
Weiwe Wang is a Senior Medical Physicist in Medical Physics Department at Shanghai Proton and Heavy Ion Center, Shanghai, China.
Kambiz Shahnazi
Kambiz Shahnazi, PhD, is a Chief Medical Physicist in Medical Physics Department at Shanghai Proton and Heavy Ion Center, Shanghai, China.
Jiayao Sun
Jiayao Sun is a Medical Physicist in Medical Physics Department at Shanghai Proton and Heavy Ion Center, Shanghai, China.
Qing Zhang
Qing Zhang, MD, is a Senior Radiotherapy Oncologist at Shanghai Proton and Heavy Ion Center, whose field is abdomen carcinoma.
Ping Li
Ping Li is an experienced Radiotherapy Oncologist at Shanghai Proton and Heavy Ion Center, whose field is abdomen carcinoma.
Zhengshan Hong
Zhengshan Hong, PhD, is a Radiotherapy Oncologist at Shanghai Proton and Heavy Ion Center, whose field is abdomen carcinoma.
Yinxiangzi Sheng
Yinxiangzi Sheng, PhD, is an Associate Professor at the Shanghai Proton and Heavy Ion Center. He has over 7 years' clinical and research experience in particle therapy. His current research program focuses on motion interplay effect evaluation and mitigation in particle therapy.