{"title":"多离子放射治疗骨及软组织肉瘤增加线性能量转移的可能性","authors":"Hideyuki Takei, Reiko Imai, Takamitsu Masuda, Katsumi Aoki, Taku Nakaji, Yusuke Nomura, Asami Inomata, Yui Suzuki, Taku Inaniwa","doi":"10.1002/mp.18097","DOIUrl":null,"url":null,"abstract":"<div>\n \n \n <section>\n \n <h3> Background</h3>\n \n <p>Multi-ion radiotherapy using carbon, oxygen, and neon ions aims to improve local control by increasing dose-averaged linear energy transfer (LET<sub>d</sub>) in the target. However, there has been limited understanding of how to utilize variables for multi-ion treatment planning such as the selection and arrangement of ion species.</p>\n </section>\n \n <section>\n \n <h3> Purpose</h3>\n \n <p>An in silico study was conducted to explore the feasibility of increasing a minimum LET<sub>d</sub>, and the optimal selection and arrangement of ion species in multi-ion therapy for increasing LET<sub>d</sub> in tumors of varying sizes mimicking bone and soft tissue sarcomas (BSTS). Additionally, the robustness of multi-ion therapy against setup and range errors was evaluated.</p>\n </section>\n \n <section>\n \n <h3> Methods</h3>\n \n <p>Spherical targets of 500, 1000, and 1500-mL volumes were placed at the center or 80 mm horizontally displaced from the center of a numerical phantom to simulate BSTS treatments. Treatment plans were made for these targets with two orthogonal fields of carbon-only, oxygen+carbon, and neon+carbon ions with a total dose of 70.4 Gy (RBE). The treatment parameters were optimized to increase the LET<sub>d</sub> in the targets while ensuring adequate target dose coverage and dose homogeneity. The plans were evaluated based on the dose covering 95% of the target (<i>D</i><sub>95%</sub>), skin dose (<i>D</i><sub>skin</sub>), and the minimum LET<sub>d</sub> excluding the 1 mL volume with the lowest LET<sub>d</sub> (<i>L</i><sub>1mL</sub>). Multi-ion radiotherapy treatment plans were also developed for 12 patients with BSTS who had previously received carbon-ion radiotherapy. <i>D</i><sub>95%</sub> and <i>L</i><sub>1m</sub> of the target, and the dose to organs at risk (OARs) such as the rectum, intestine, and spinal cord were assessed. The robustness of the plans created in the phantom against setup and range errors was evaluated under 2 mm shifts in six directions combined with 2.5% variation of the stopping power ratio, resulting in 12 scenarios. Differences in the target <i>D</i><sub>95%</sub> and <i>L</i><sub>1mL</sub>, and <i>D</i><sub>skin</sub> in each scenario from those in the nominal plan were evaluated.</p>\n </section>\n \n <section>\n \n <h3> Results</h3>\n \n <p>The target dose coverage was comparable for any ion species combinations regardless of target size and position. The <i>L</i><sub>1mL</sub> in the target increased by 7–9 and 15–20 keV/µm with the oxygen+carbon and neon+carbon plans, respectively, compared to the carbon-only plans, while maintaining homogeneity index values below 0.10. Additionally, the skin dose increased by 2.2–7.0 and 9.2–14.6 Gy (RBE) for the oxygen+carbon and neon+carbon plans. The <i>L</i><sub>1mL</sub> was greater than or equal to 40 keV/µm in all phantom targets and most clinical cases for the oxygen+carbon and neon+carbon plans, while meeting the target and OAR dose requirements. In the robustness evaluation, the variations in <i>D</i><sub>95%</sub> were comparable or smaller in the oxygen+carbon and neon+carbon plans than in the carbon-only plan. The maximum decrease in <i>L</i><sub>1mL</sub> in the target was 1.5 keV/µm. The maximum increase in <i>D</i><sub>skin</sub> was 2.4 Gy (RBE) in the target closest to the skin.</p>\n </section>\n \n <section>\n \n <h3> Conclusions</h3>\n \n <p>The LET<sub>d</sub> was successfully increased with the oxygen+carbon and neon+carbon ions, while meeting the dose requirements. The multi-ion therapy plans created using the method presented in this study were robust to setup and range errors.</p>\n </section>\n </div>","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 9","pages":""},"PeriodicalIF":3.2000,"publicationDate":"2025-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Possibility of increasing linear energy transfer in multi-ion radiotherapy for bone and soft tissue sarcomas\",\"authors\":\"Hideyuki Takei, Reiko Imai, Takamitsu Masuda, Katsumi Aoki, Taku Nakaji, Yusuke Nomura, Asami Inomata, Yui Suzuki, Taku Inaniwa\",\"doi\":\"10.1002/mp.18097\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div>\\n \\n \\n <section>\\n \\n <h3> Background</h3>\\n \\n <p>Multi-ion radiotherapy using carbon, oxygen, and neon ions aims to improve local control by increasing dose-averaged linear energy transfer (LET<sub>d</sub>) in the target. However, there has been limited understanding of how to utilize variables for multi-ion treatment planning such as the selection and arrangement of ion species.</p>\\n </section>\\n \\n <section>\\n \\n <h3> Purpose</h3>\\n \\n <p>An in silico study was conducted to explore the feasibility of increasing a minimum LET<sub>d</sub>, and the optimal selection and arrangement of ion species in multi-ion therapy for increasing LET<sub>d</sub> in tumors of varying sizes mimicking bone and soft tissue sarcomas (BSTS). Additionally, the robustness of multi-ion therapy against setup and range errors was evaluated.</p>\\n </section>\\n \\n <section>\\n \\n <h3> Methods</h3>\\n \\n <p>Spherical targets of 500, 1000, and 1500-mL volumes were placed at the center or 80 mm horizontally displaced from the center of a numerical phantom to simulate BSTS treatments. Treatment plans were made for these targets with two orthogonal fields of carbon-only, oxygen+carbon, and neon+carbon ions with a total dose of 70.4 Gy (RBE). The treatment parameters were optimized to increase the LET<sub>d</sub> in the targets while ensuring adequate target dose coverage and dose homogeneity. The plans were evaluated based on the dose covering 95% of the target (<i>D</i><sub>95%</sub>), skin dose (<i>D</i><sub>skin</sub>), and the minimum LET<sub>d</sub> excluding the 1 mL volume with the lowest LET<sub>d</sub> (<i>L</i><sub>1mL</sub>). Multi-ion radiotherapy treatment plans were also developed for 12 patients with BSTS who had previously received carbon-ion radiotherapy. <i>D</i><sub>95%</sub> and <i>L</i><sub>1m</sub> of the target, and the dose to organs at risk (OARs) such as the rectum, intestine, and spinal cord were assessed. The robustness of the plans created in the phantom against setup and range errors was evaluated under 2 mm shifts in six directions combined with 2.5% variation of the stopping power ratio, resulting in 12 scenarios. Differences in the target <i>D</i><sub>95%</sub> and <i>L</i><sub>1mL</sub>, and <i>D</i><sub>skin</sub> in each scenario from those in the nominal plan were evaluated.</p>\\n </section>\\n \\n <section>\\n \\n <h3> Results</h3>\\n \\n <p>The target dose coverage was comparable for any ion species combinations regardless of target size and position. The <i>L</i><sub>1mL</sub> in the target increased by 7–9 and 15–20 keV/µm with the oxygen+carbon and neon+carbon plans, respectively, compared to the carbon-only plans, while maintaining homogeneity index values below 0.10. Additionally, the skin dose increased by 2.2–7.0 and 9.2–14.6 Gy (RBE) for the oxygen+carbon and neon+carbon plans. The <i>L</i><sub>1mL</sub> was greater than or equal to 40 keV/µm in all phantom targets and most clinical cases for the oxygen+carbon and neon+carbon plans, while meeting the target and OAR dose requirements. In the robustness evaluation, the variations in <i>D</i><sub>95%</sub> were comparable or smaller in the oxygen+carbon and neon+carbon plans than in the carbon-only plan. The maximum decrease in <i>L</i><sub>1mL</sub> in the target was 1.5 keV/µm. The maximum increase in <i>D</i><sub>skin</sub> was 2.4 Gy (RBE) in the target closest to the skin.</p>\\n </section>\\n \\n <section>\\n \\n <h3> Conclusions</h3>\\n \\n <p>The LET<sub>d</sub> was successfully increased with the oxygen+carbon and neon+carbon ions, while meeting the dose requirements. The multi-ion therapy plans created using the method presented in this study were robust to setup and range errors.</p>\\n </section>\\n </div>\",\"PeriodicalId\":18384,\"journal\":{\"name\":\"Medical physics\",\"volume\":\"52 9\",\"pages\":\"\"},\"PeriodicalIF\":3.2000,\"publicationDate\":\"2025-09-10\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Medical physics\",\"FirstCategoryId\":\"3\",\"ListUrlMain\":\"https://aapm.onlinelibrary.wiley.com/doi/10.1002/mp.18097\",\"RegionNum\":2,\"RegionCategory\":\"医学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Medical physics","FirstCategoryId":"3","ListUrlMain":"https://aapm.onlinelibrary.wiley.com/doi/10.1002/mp.18097","RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING","Score":null,"Total":0}
Possibility of increasing linear energy transfer in multi-ion radiotherapy for bone and soft tissue sarcomas
Background
Multi-ion radiotherapy using carbon, oxygen, and neon ions aims to improve local control by increasing dose-averaged linear energy transfer (LETd) in the target. However, there has been limited understanding of how to utilize variables for multi-ion treatment planning such as the selection and arrangement of ion species.
Purpose
An in silico study was conducted to explore the feasibility of increasing a minimum LETd, and the optimal selection and arrangement of ion species in multi-ion therapy for increasing LETd in tumors of varying sizes mimicking bone and soft tissue sarcomas (BSTS). Additionally, the robustness of multi-ion therapy against setup and range errors was evaluated.
Methods
Spherical targets of 500, 1000, and 1500-mL volumes were placed at the center or 80 mm horizontally displaced from the center of a numerical phantom to simulate BSTS treatments. Treatment plans were made for these targets with two orthogonal fields of carbon-only, oxygen+carbon, and neon+carbon ions with a total dose of 70.4 Gy (RBE). The treatment parameters were optimized to increase the LETd in the targets while ensuring adequate target dose coverage and dose homogeneity. The plans were evaluated based on the dose covering 95% of the target (D95%), skin dose (Dskin), and the minimum LETd excluding the 1 mL volume with the lowest LETd (L1mL). Multi-ion radiotherapy treatment plans were also developed for 12 patients with BSTS who had previously received carbon-ion radiotherapy. D95% and L1m of the target, and the dose to organs at risk (OARs) such as the rectum, intestine, and spinal cord were assessed. The robustness of the plans created in the phantom against setup and range errors was evaluated under 2 mm shifts in six directions combined with 2.5% variation of the stopping power ratio, resulting in 12 scenarios. Differences in the target D95% and L1mL, and Dskin in each scenario from those in the nominal plan were evaluated.
Results
The target dose coverage was comparable for any ion species combinations regardless of target size and position. The L1mL in the target increased by 7–9 and 15–20 keV/µm with the oxygen+carbon and neon+carbon plans, respectively, compared to the carbon-only plans, while maintaining homogeneity index values below 0.10. Additionally, the skin dose increased by 2.2–7.0 and 9.2–14.6 Gy (RBE) for the oxygen+carbon and neon+carbon plans. The L1mL was greater than or equal to 40 keV/µm in all phantom targets and most clinical cases for the oxygen+carbon and neon+carbon plans, while meeting the target and OAR dose requirements. In the robustness evaluation, the variations in D95% were comparable or smaller in the oxygen+carbon and neon+carbon plans than in the carbon-only plan. The maximum decrease in L1mL in the target was 1.5 keV/µm. The maximum increase in Dskin was 2.4 Gy (RBE) in the target closest to the skin.
Conclusions
The LETd was successfully increased with the oxygen+carbon and neon+carbon ions, while meeting the dose requirements. The multi-ion therapy plans created using the method presented in this study were robust to setup and range errors.
期刊介绍:
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