Potential benefits of using radioactive ion beams for range margin reduction in carbon ion therapy

Sokol, Olga; Cella, Laura; Boscolo, Daria; Horst, Felix; Oliviero, C.; Pacelli, Roberto; Palma, Giuseppe; Simoni, Micol De; Conson, Manuel; Caroprese, Mara; Weber, Ulrich; Graeff, Christian; Parodi, Katia; Durante, Marco

doi:10.1038/s41598-022-26290-z

Cited by 8 publications

(3 citation statements)

References 53 publications

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“…As already shown in Figure S14, LET d optimization lead to some sort of distal patching and thus, anatomical changes and range uncertainties are expected to cause challenges in terms of robustness. The introduction of other modalities, such as dual energy CT 27 or innovative range uncertainty mitigating approaches (e.g., using radioactive ion beams 28 or exploiting a mixed helium/carbon beam for online monitoring 29 ), could reduce uncertainties in stopping power estimation. This may have a positive impact on increasing the LET d in large tumors by minimizing the range uncertainty considered in robust optimization.The robustness evaluation performed in this study represents a very conservative approach, assessing a worst case scenario of having the same systematic error, in the same direction, repeated in every fraction.…”

Section: Discussionmentioning

confidence: 99%

Dose averaged linear energy transfer optimization for large sacral chordomas in carbon ion therapy

Schafasand,

Resch,

Nachankar

et al. 2024

Medical Physics

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BackgroundCarbon ion beams are well accepted as densely ionizing radiation with a high linear energy transfer (LET). However, the current clinical practice does not fully exploit the highest possible dose‐averaged LET (LETd) and, consequently, the biological potential in the target. This aspect becomes worse in larger tumors for which inferior clinical outcomes and corresponding lower LETd was reported.PurposeThe vicinity to critical organs in general and the inferior overall survival reported for larger sacral chordomas treated with carbon ion radiotherapy (CIRT), makes the treatment of such tumors challenging. In this work it was aimed to increase the LETd in large volume tumors while maintaining the relative biological effectiveness (RBE)‐weighted dose, utilizing the LETd optimization functions of a commercial treatment planning system (TPS).MethodsTen reference sequential boost carbon ion treatment plans, designed to mimic clinical plans for large sacral chordoma tumors, were generated. High dose clinical target volumes (CTV‐HD) larger than were considered as large targets. The total RBE‐weighted median dose prescription with the local effect model (LEM) was in 16 fractions (nine to low dose and seven to high dose planning target volume). No LETd optimization was performed in the reference plans, while LETd optimized plans used the minimum LETd (Lmin) optimization function in RayStation 2023B. Three different Lmin values were investigated and specified for the seven boost fractions: , and . To compare the LETd optimized against reference plans, LETd and RBE‐weighted dose based goals similar to and less strict than clinical ones were specified for the target. The goals for the organs at risk (OAR) remained unchanged. Robustness evaluation was studied for eight scenarios ( range uncertainty and setup uncertainty along the main three axes).ResultsThe optimization method with resulted in an optimal LETd distribution with an average increase of (and ) in the CTV‐HD by () (and ()), without significant difference in the RBE‐weighted dose. By allowing over‐ and under‐dosage in the target, the (and ) can be increased by () (and ()), using the optimization parameters . The pass rate for the OAR goals in the LETd optimized plans was in the same level as the reference plans. LETd optimization lead to less robust plans compared to reference plans.ConclusionsCompared to conventionally optimized treatment plans, the LETd in the target was increased while maintaining the RBE‐weighted dose using TPS LETd optimization functionalities. Regularly assessing RBE‐weighted dose robustness and acquiring more in‐room images remain crucial and inevitable aspects during treatment.

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Section: Discussionmentioning

confidence: 99%

Dose averaged linear energy transfer optimization for large sacral chordomas in carbon ion therapy

Schafasand,

Resch,

Nachankar

et al. 2024

Medical Physics

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“…Although 10 C would be the ideal isotope among the candidates for a positron-emitting treatment beam in terms of half-life, its low production cross-section makes it challenging to achieve therapeutic intensities through projectile fragmentation. On the other hand, 11 C has a production cross-section roughly one order of magnitude higher, but its half-life is too long to be considered for fast range monitoring using in-beam PET.…”

Section: Discussionmentioning

confidence: 99%

Quasi-real-time range monitoring by in-beam PET: A case for 15O

Purushothaman

Kostyleva

Dendooven

et al. 2023

Preprint

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fast and reliable range monitoring method is required to take full advantage of the high linear energy transfer (LET) provided by therapeutic ion beams like carbon and oxygen while minimizing damage to healthy tissue due to range uncertainties. Quasi-real-time range monitoring using in-beam positron emission tomography (PET) with positron-emitting isotopes of carbon and oxygen is a promising approach. The number of implanted ions and the time required for an unambiguous range verification are decisive factors for choosing a candidate isotope. An experimental study was performed at the FRS fragment-separator facility of GSI Helmholtzzentrum für Schwerionenforschung GmbH, Germany, to investigate the evolution of positron annihilation activity profiles during the implantation of 14O and 15O ion beams in a PMMA phantom. The positron activity profile was imaged by a dual-panel version of a Siemens Biograph mCT PET scanner. Results from a similar experiment using ion beams of carbon positron-emitters 11C and 10C performed at the same experimental setup were used for comparison. Owing to their shorter half-lives, the number of implanted ions required for a precise positron annihilation activity peak determination is lower for 10C compared to 11C and likewise for 14O compared to 15O, but their lower production cross-section makes it challenging to produce them with intensities of therapeutical needs. With a similar production cross-section and a 10 times shorter half-life than 11C, 15O provides a faster conclusive positron annihilation activity peak position determination for a lower number of implanted ions compared to 11C. We conclude that 15O is technically the most feasible candidate among positron emitters of carbon and oxygen for quasi-real-time in-beam range monitoring in ion beam therapy. The study also demonstrated that 15O beams of therapeutical quality in terms of purity, energy, and energy spread can be produced by the in-flight production and separation method.

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“…Additionally, patient anatomical changes may occur during treatment. To address this, margins are typically added to the treated region, which unfortunately causes unnecessary dose deposition to healthy tissue, ultimately leading to increased toxicity 10 . Positron emission tomography (PET) is one of the most commonly employed methods to monitor dose delivery in ion beam therapy 11 .…”

Section: Introductionmentioning

confidence: 99%

Quasi-real-time range monitoring by in-beam PET: a case for 15O

Purushothaman,

Kostyleva,

Dendooven

et al. 2023

Sci Rep

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A fast and reliable range monitoring method is required to take full advantage of the high linear energy transfer provided by therapeutic ion beams like carbon and oxygen while minimizing damage to healthy tissue due to range uncertainties. Quasi-real-time range monitoring using in-beam positron emission tomography (PET) with therapeutic beams of positron-emitters of carbon and oxygen is a promising approach. The number of implanted ions and the time required for an unambiguous range verification are decisive factors for choosing a candidate isotope. An experimental study was performed at the FRS fragment-separator of GSI Helmholtzzentrum für Schwerionenforschung GmbH, Germany, to investigate the evolution of positron annihilation activity profiles during the implantation of $$^{14}$$ 14 O and $$^{15}$$ 15 O ion beams in a PMMA phantom. The positron activity profile was imaged by a dual-panel version of a Siemens Biograph mCT PET scanner. Results from a similar experiment using ion beams of carbon positron-emitters $$^{11}$$ 11 C and $$^{10}$$ 10 C performed at the same experimental setup were used for comparison. Owing to their shorter half-lives, the number of implanted ions required for a precise positron annihilation activity peak determination is lower for $$^{10}$$ 10 C compared to $$^{11}$$ 11 C and likewise for $$^{14}$$ 14 O compared to $$^{15}$$ 15 O, but their lower production cross-sections make it difficult to produce them at therapeutically relevant intensities. With a similar production cross-section and a 10 times shorter half-life than $$^{11}$$ 11 C, $$^{15}$$ 15 O provides a faster conclusive positron annihilation activity peak position determination for a lower number of implanted ions compared to $$^{11}$$ 11 C. A figure of merit formulation was developed for the quantitative comparison of therapy-relevant positron-emitting beams in the context of quasi-real-time beam monitoring. In conclusion, this study demonstrates that among the positron emitters of carbon and oxygen, $$^{15}$$ 15 O is the most feasible candidate for quasi-real-time range monitoring by in-beam PET that can be produced at therapeutically relevant intensities. Additionally, this study demonstrated that the in-flight production and separation method can produce beams of therapeutic quality, in terms of purity, energy, and energy spread.

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Potential benefits of using radioactive ion beams for range margin reduction in carbon ion therapy

Cited by 8 publications

References 53 publications

Dose averaged linear energy transfer optimization for large sacral chordomas in carbon ion therapy

Dose averaged linear energy transfer optimization for large sacral chordomas in carbon ion therapy

Quasi-real-time range monitoring by in-beam PET: A case for 15O

Quasi-real-time range monitoring by in-beam PET: a case for 15O

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