Calculating dose‐averaged linear energy transfer in an analytical treatment planning system for carbon‐ion radiotherapy

Wang, Weiwei; Li, Ping; Shahnazi, Kambiz; Wu, Xiaodong; Zhao, Jing

doi:10.1002/acm2.13866

Cited by 7 publications

(3 citation statements)

References 20 publications

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“…The accuracy of the simulation to measurements may be a source of uncertainty. Our previous study demonstrated that the fragment spectra in RayStation overestimated the LET distally compared to the fragment spectra in Syngo [ 34 ]. Moreover, the different types of MC toolkits may be another reason.…”

Section: Discussionmentioning

confidence: 99%

Validation of the relative biological effectiveness of active-energy scanning carbon-ion radiotherapy on a commercial treatment planning system with a microdosimetic kinetic model

et al. 2023

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Background The study objective was to validate the relative biological effectiveness (RBE) calculated by the modified microdosimetric kinetic model in RayStation (Ray-MKM) for active-energy scanning carbon-ion radiotherapy. Methods The Ray-MKM was benchmarked using a spread-out Bragg-peak (SOBP) plan, which was suggested in literature from the National Institute of Radiobiological Science (NIRS) in Japan. The residual RBE differences from the MKM at NIRS (NIRS-MKM) were derived using several SOBP plans with different ranges, SOBP widths, and prescriptions. To investigate the origins of the differences, we compared the saturation-corrected dose-mean specific energy $$Z_{1D}^{*}$$ Z 1 D ∗ of the aforementioned SOBPs. Furthermore, we converted the RBE-weighted doses with the Ray-MKM to those with local effect model I (LEM doses). The purpose was to investigate whether the Ray-MKM could reproduce the RBE-weighted conversion study. Results The benchmark determined the value of the clinical dose scaling factor, $$F_{clin}$$ F clin , as 2.40. The target mean RBE deviations between the Ray-MKM and NIRS-MKM were median: 0.6 (minimum: 0.0 to maximum: 1.69) %. The $$Z_{1D}^{*}$$ Z 1 D ∗ difference in-depth led to the RBE difference in-depth and was remarkable at the distal end. The converted LEM doses from the Ray-MKM doses were comparable (the deviation being − 1.8–0.7%) to existing literature. Conclusion This study validated the Ray-MKM based on our active-energy scanning carbon-ion beam via phantom studies. The Ray-MKM could generate similar RBEs as the NIRS-MKM after benchmarking. Analysis based on $$Z_{1D}^{*}$$ Z 1 D ∗ indicated that the different beam qualities and fragment spectra caused the RBE differences. Since the absolute dose differences at the distal end were small, we neglected them. Furthermore, each centre may determine its centre-specific $$F_{clin}$$ F clin based on this approach.

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Section: Discussionmentioning

confidence: 99%

Validation of the relative biological effectiveness of active-energy scanning carbon-ion radiotherapy on a commercial treatment planning system with a microdosimetic kinetic model

et al. 2023

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“…The CIRT LET d in patients was calculated according to our approach. 12 The conversion from LET d to OER was based on a systematic study using CHO cells. 13 Equation ( 1 ) is displayed as follows:

where p O 2 is the tumor oxygen level.…”

Section: Methodsmentioning

confidence: 99%

“…The CIRT LET d in patients was calculated according to our approach 12 . The conversion from LET d to OER was based on a systematic study using CHO cells 13 .…”

Section: Methodsmentioning

confidence: 99%

Up modulation of dose‐averaged linear energy transfer by simultaneous integrated boost in carbon‐ion radiotherapy for pancreatic carcinoma

Wang,

Sun,

Zhao

et al. 2024

J Applied Clin Med Phys

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BackgroundLocal recurrence in locally advanced pancreatic cancer (LAPC) after carbon‐ion radiotherapy (CIRT) may partly attribute to low dose‐averaged linear energy transfer (LETd), despite high CIRT dose.PurposeThis study aimed to investigate the approaches to up‐modulate the CIRT LETd and to evaluate the corresponding oxygen enhancement ratio (OER) reduction.Methods10 LAPCs that had been irradiated by CIRT with 67.5 Gy (RBE) in 15 fractions were selected. Their original plans were taken as the control plan for the LETd and OER investigations. Our considerations for up‐modulating LETd were: (1) to deliver high doses to gross tumor volume core (GTVcore), while keeping dose constraints of the gastrointestinal (GI) tract in tolerance; (2) to put more Bragg‐peak (BP) within the modulated targets; (3) to increase the BP density, high doses were necessary; (4) CIRT LETd could be effectively increased to small volumes; and (5) simultaneous integrated boost technique (SIB) could achieve the aforementioned tasks. The LETd and the corresponding OER distributions of each type of SIB plan were evaluated.ResultsWe delivered up to 100 Gy (RBE) to GTVcore using SIB. The mean LETd of GTV increased significantly by 21.3% from 47.8 to 58.0 keV/μm (p < 0.05). Meanwhile, the mean OER of GTVcore decreased by 6.6%, from 1.51 to 1.41 (p < 0.05). The GI LETdS in all modulated plans were not more than those in the original plans.ConclusionsSIB could effectively increase CIRT LETd to LAPC, thus producing reduced OER, which may effectively overcome the radioresistance of LAPCs.

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Calculating dose‐averaged linear energy transfer in an analytical treatment planning system for carbon‐ion radiotherapy

Wang

Li²,

Shahnazi

et al. 2022

J Applied Clin Med Phys

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Background Compelling evidence shows the association between the relative biological effectiveness (RBE) of carbon‐ion radiotherapy (CIRT) and the dose averaged linear energy transfer ( LETd ). However, the ability to calculate the LETd in commercially available treatment planning systems (TPS) is lacking. Purpose This study aims to develop a method of calculating the LETd of CIRT plans that could be robustly carried out in RayStation (V10B, Raysearch, Sweden). Methods The calculation used the fragment spectra in RayStation for the CIRT treatment planning. The dose‐weighted averaging procedure was supported by the microdosimetric kinetic model (MKM). The MKM‐based pencil beam dose engine (PBA, v4.2) for calculating RBE‐weighted doses was reformulated to become a LET ‐weighted calculating engine. A separate module was then configured to inversely calculate the LETd from the absorbed dose of a plan and the associated fragment spectra. In this study, the ion and energy‐specific LET table in the LETd module was further matched with the values decoded from the baseline data of the Syngo TPS (V13C, Siemens, Germany). The LETd distributions of several monoenergetic and modulated beams were calculated and validated against the values derived from the Syngo TPS and the published data. Results The differences in LETds of the monoenergetic beams between the new method and the traditional method were within 3% in the entrance and Bragg‐peak regions. However, a larger difference was observed in the distal region. The results of the modulated beams were in good agreement with the works from the published literature. Conclusions The method presented herein reformulates the MKM dose engine in the RayStation TPS to inversely calculate LETds . The robustness and accuracy were demonstrated.

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Calculating dose‐averaged linear energy transfer in an analytical treatment planning system for carbon‐ion radiotherapy

Cited by 7 publications

References 20 publications

Validation of the relative biological effectiveness of active-energy scanning carbon-ion radiotherapy on a commercial treatment planning system with a microdosimetic kinetic model

Validation of the relative biological effectiveness of active-energy scanning carbon-ion radiotherapy on a commercial treatment planning system with a microdosimetic kinetic model

Up modulation of dose‐averaged linear energy transfer by simultaneous integrated boost in carbon‐ion radiotherapy for pancreatic carcinoma

Calculating dose‐averaged linear energy transfer in an analytical treatment planning system for carbon‐ion radiotherapy

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