Unresectable Chondrosarcomas Treated With Carbon Ion Radiotherapy: Relationship Between Dose-averaged Linear Energy Transfer and Local Recurrence

Matsumoto, Shinnosuke; Lee, Sung Hyun; Imai, Reiko; Inaniwa, Taku; Matsufuji, Naruhiro; Fukahori, Mai; Kohno, Ryosuke; Yonai, Shunsuke; Okonogi, Noriyuki; Yamada, Shigeru; Kanematsu, Nobuyuki

doi:10.21873/anticanres.14664

Cited by 23 publications

(17 citation statements)

References 30 publications

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“…Different LET-based optimization strategies, for example, LET painting [12][13][14] or kill-painting 15 have been proposed in the last years to improve the outcomes of CIRT. Furthermore, recent studies try more often to correlate the LET or LET-based evaluators to the clinical outcomes of patients treated with CIRT [16][17][18] and thus, the demand for a validated and standardized LET calculation in CIRT is increasing.…”

Section: Introductionmentioning

confidence: 99%

Technical note: In silico benchmarking of the linear energy transfer‐based functionalities for carbon ion beams in a commercial treatment planning system

et al. 2023

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Background:The increasing number of studies dealing with linear energy transfer (LET)-based evaluation and optimization in the field of carbon ion radiotherapy (CIRT) indicates the rising demand for LET implementation in commercial treatment planning systems (TPS). Benchmarking studies could play a key role in detecting (and thus preventing) computation errors prior implementing such functionalities in a TPS. Purpose: This in silico study was conducted to benchmark the following two LET-related functionalities in a commercial TPS against Monte Carlo simulations: (1) dose averaged LET (LET d ) scoring and (2) physical dose filtration based on LET for future LET-based treatment plan evaluation and optimization studies. Methods: The LET d scoring and LET-based dose filtering (in which the deposited dose can be separated into the dose below and above the user specified LET threshold) functionalities for carbon ions in the research version RayStation (RS) 9A-IonPG TPS (RaySearch Laboratories, Sweden) were benchmarked against GATE/Geant4 simulations. Pristine Bragg peaks (BPs) and cuboid targets, positioned at different depths in a homogeneous water phantom and a setup with heterogeneity were used for this study. Results: For all setups (homogeneous and heterogeneous), the mean absolute (and relative) LET d difference was less than 1 keV/μm (3.5%) in the plateau and target and less than 2 keV/μm (8.3%) in the fragmentation tail. The maximum local differences were 4 and 6 keV/μm, respectively. The mean absolute (and relative) physical dose differences for both low-and high-LET doses were less than 1 cGy (1.5%) in the plateau, target and tail with a maximum absolute difference of 2 cGy. Conclusions: No computation error was found in the tested functionalities except for LET d in lateral direction outside the target, showing the limitation of the implemented monochrome model in the tested TPS version.

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Section: Introductionmentioning

confidence: 99%

Technical note: In silico benchmarking of the linear energy transfer‐based functionalities for carbon ion beams in a commercial treatment planning system

et al. 2023

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“…Masumoto et al. conducted a study on the correlation between local recurrence and intra tumour LET distribution, and found that no recurrence was found when the minimum dose-averaged LET value did not exceed 40 keV/μm ( 29 ). Hagiwara et al.…”

Section: Discussionmentioning

confidence: 99%

Dosimetric comparison of robust angles in carbon-ion radiation therapy for prostate cancer

Shin

Kim²,

Han³

et al. 2023

Front. Oncol.

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The objective of this study is to compare the plan robustness at various beam angles. Hence, the influence of the beam angles on robustness and linear energy transfer (LET) was evaluated in gantry-based carbon-ion radiation therapy (CIRT) for prostate cancer. 10 patients with prostate cancer were considered, and a total dose of 51.6 Gy (Relative biological effectiveness (RBE) was prescribed for the target volume in 12 fractions. Five beam field plans comprising two opposed fields with different angle pairs were characterized. Further, dose parameters were extracted, and the RBE-weighted dose and LET values for all angle pairs were compared. All plans considering the setup uncertainty satisfied the dose regimen. When a parallel beam pair was used for perturbed scenarios to take into account set-up uncertainty in the anterior direction, the LET clinical treatment volume (CTV) D95% standard deviation was 1.5 times higher, and the standard deviation of RBE-weighted CTV D95% was 7.9 times higher compared to an oblique pair. The oblique beam fields were superior in terms of dose sparing for the rectum compared to the dose distribution using two conventional lateral opposed fields for prostate cancer.

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“…7,8 One of the most promising treatments of unresectable pancreatic cancers is high LET carbon ions: in a retrospective analysis, pancreatic cancer patients that received a higher minimum LET d in the GTV had a higher probability of local control than patients with lower minimum LET d . 8 Related, the local control rate for chondrosarcomas decreases as the tumor size increases, which could be due to the lower LET d in larger tumors, 9 and overdosage in the target in combination with high LET in the hypoxic regions has been used as a means to increase the theoretical tumor control probability. 1 The range of ion beams is highly affected by the density of the traversed media.…”

Section: Introductionmentioning

confidence: 99%

The LET trilemma: Conflicts between robust target coverage, uniform dose, and dose‐averaged LET in carbon therapy

Fredriksson,

Glimelius,

Bokrantz

2023

Medical Physics

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BackgroundLinear energy transfer (LET) is closely related to the biological effect of ionizing radiation. Increasing the dose‐averaged LET (LETd) within the target volume has been proposed as a means to improve clinical outcome for hypoxic tumors. However, doing so can lead to reduced robustness to range uncertainty.PurposeTo quantify the relationship between robust target coverage, target dose uniformity, and LETd, we employ robust optimization using dose‐based and LETd‐based functions and allow varying amounts of target non‐uniformity.Methods and MaterialsRobust carbon therapy optimization is used to create plans for phantom cases with increasing target sizes (radii 1, 3, and 5 cm). First, the influence of respectively range and setup uncertainty on the LETd in the target is studied. Second, we employ strategies allowing overdosage in the clinical target volume (CTV) or gross tumor volume (GTV), which enable increased LETd in the target. The relationship between robust target coverage and LETd in the target is illustrated by tradeoff curves generated by optimization using varying weights for the LETd‐based functions.ResultsAs the range uncertainty used in the robust optimization increased from 0% to 5%, the near‐minimum nominal LETd decreased by 17%–29% (9–21 keV/µm) for the different target sizes. The effect of increasing setup uncertainty was marginal. Allowing 10% overdosage in the CTV enabled 9%–29% (6–12 keV/µm) increased near‐minimum worst case LETd for the different target sizes, compared to uniform dose plans. When 10% overdosage was allowed in the GTV only, the increase was 1%–20% (1–8 keV/µm).ConclusionsThere is an inherent conflict between range uncertainty robustness and high LETd in the target, which is aggravated with increasing target size. For large tumors, it is possible to simultaneously achieve two of the three qualities range robustness, uniform dose, and high LETd in the target.

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Unresectable Chondrosarcomas Treated With Carbon Ion Radiotherapy: Relationship Between Dose-averaged Linear Energy Transfer and Local Recurrence

Cited by 23 publications

References 30 publications

Technical note: In silico benchmarking of the linear energy transfer‐based functionalities for carbon ion beams in a commercial treatment planning system

Technical note: In silico benchmarking of the linear energy transfer‐based functionalities for carbon ion beams in a commercial treatment planning system

Dosimetric comparison of robust angles in carbon-ion radiation therapy for prostate cancer

The LET trilemma: Conflicts between robust target coverage, uniform dose, and dose‐averaged LET in carbon therapy

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