Dosimetric Validation of a System to Treat Moving Tumors Using Scanned Ion Beams That Are Synchronized With Anatomical Motion

Lis, Michelle; Newhauser, Wayne D.; Donetti, M.; Wolf, Moritz; Steinsberger, Timo; Paz, Athena; Graeff, Christian

doi:10.3389/fonc.2021.712126

Cited by 7 publications

(2 citation statements)

References 43 publications

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“…Now, with commercial options for vertical CT systems (8,9), and the drive for reducing the upfront investment for opening new particle therapy centers (3,10), upright treatment positioning systems have gained renewed interest (11,12). Moreover, advanced techniques for intra-treatment verification and adaptation (13)(14)(15) are currently reaching clinical maturity. These techniques could, not only overcome the previous issues associated with anatomical motion for upright treatment positions, but together with upright treatment postures, further open possibilities for advanced beam delivery schemes, e.g., particle arc therapy (16) with continuous patient rotation.…”

Section: Introductionmentioning

confidence: 99%

Considerations for Upright Particle Therapy Patient Positioning and Associated Image Guidance

et al. 2022

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Particle therapy is a rapidly growing field in cancer therapy. Worldwide, over 100 centers are in operation, and more are currently in construction phase. The interest in particle therapy is founded in the superior target dose conformity and healthy tissue sparing achievable through the particles’ inverse depth dose profile. This physical advantage is, however, opposed by increased complexity and cost of particle therapy facilities. Particle therapy, especially with heavier ions, requires large and costly equipment to accelerate the particles to the desired treatment energy and steer the beam to the patient. A significant portion of the cost for a treatment facility is attributed to the gantry, used to enable different beam angles around the patient for optimal healthy tissue sparing. Instead of a gantry, a rotating chair positioning system paired with a fixed horizontal beam line presents a suitable cost-efficient alternative. Chair systems have been used already at the advent of particle therapy, but were soon dismissed due to increased setup uncertainty associated with the upright position stemming from the lack of dedicated image guidance systems. Recently, treatment chairs gained renewed interest due to the improvement in beam delivery, commercial availability of vertical patient CT imaging and improved image guidance systems to mitigate the problem of anatomical motion in seated treatments. In this review, economical and clinical reasons for an upright patient positioning system are discussed. Existing designs targeted for particle therapy are reviewed, and conclusions are drawn on the design and construction of chair systems and associated image guidance. Finally, the different aspects from literature are channeled into recommendations for potential upright treatment layouts, both for retrofitting and new facilities.

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Section: Introductionmentioning

confidence: 99%

Considerations for Upright Particle Therapy Patient Positioning and Associated Image Guidance

et al. 2022

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“…The gamma pass rate with a 3%/3 mm criterion could be improved from 44% to 96% for 2 cm motion and a 4 s breathing period when gating was applied. Extending these moving platform measurements by a wedge and a heterogeneous slab phantom in combination with ionisation chambers [ 30 ] showed a dose distortion of up to 30%. Such a strong effect of motion was not observed in our study delivering SOBP, where the maximal distortion of 30% was only observed for outliers.…”

Section: Discussionmentioning

confidence: 99%

The Influence of Motion on the Delivery Accuracy When Comparing Actively Scanned Carbon Ions versus Protons at a Synchrotron-Based Radiotherapy Facility

Lebbink

Georg

Knäusl

2022

Cancers

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Motion amplitudes, in need of mitigation for moving targets irradiated with pulsed carbon ions and protons, were identified to guide the decision on treatment and motion mitigation strategy. Measurements with PinPoint ionisation chambers positioned in an anthropomorphic breathing phantom were acquired to investigate different tumour motion scenarios, including rib and lung movements. The effect of beam delivery dynamics and spot characteristics was considered. The dose in the tumour centre was deteriorated up to 10% for carbon ions but only up to 5% for protons. Dose deviations in the penumbra increased by a factor of two when comparing carbon ions to protons, ranging from 2 to 30% for an increasing motion amplitude that was strongly dependent on the beam intensity. Layer rescanning was able to diminish the dose distortion caused by tumour motion, but an increase in spot size could reduce it even further to 5% within the target and 10% at the penumbra. An increased need for motion mitigation of carbon ions compared to protons was identified to assure target coverage and sparing of adjacent organs at risk in the penumbra region and outside the target. For the clinical implementation of moving target treatments at a synchrotron-based particle facility complex, time dependencies needed to be considered.

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Exploring energy selection methods for robust biologically optimized carbon ion arc for head&neck cancer patients

Volz,

Sheng,

Kong

et al. 2024

Health Technol.

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Background Due to the advantageous depth dose profile of carbon ion beams, carbon ion therapy is commonly applied in the form of intensity modulated particle therapy (IMPT) with few treatment fields. Carbon ion arc therapy (C-Arc) has recently been proposed to improve dose conformity and increase the dose-averaged linear energy transfer (LETd) inside the target to levels relevant for overcoming tumor radioresistance. In this work, we investigate different energy selection approaches for C-Arc, including a novel greedy energy layer refinement strategy. Methods Robust biologically optimized C-Arc plans were generated for six head &neck cancer patient previously treated at the Shanghai Proton and Heavy Ion Center (SPHIC). Different heuristic approaches for mono- and dual-energy C-Arc were implemented, and compared to carbon IMPT pans. A novel greedy energy layer refinement was developed, acting directly on the dose influence matrix, rather than on an iterative plan optimization. A key challenge in C-Arc with few energy layers per angle is the sharpness of the carbon ion Bragg peak, which is challenging for plan robustness. To improve robustness and plan quality, we propose the use of a 6 mm ripple filter instead of the typical 3 mm ripple filter used for carbon IMPT. Results Most mono-energetic C-Arc plans were able to meet the established clinical goals, but some of the heuristic energy selection schemes were not universally applicable with low plan quality in some patients. The developed energy layer refinement strategy delivered high quality plans even for complex cases. Mono-energetic C-Arc plans presented an average increase between 10% and 33% in the maximum LETd in the target, with similar or up to 19% improved average target LETd$$_{50\%}$$ 50 % compared to the IMPT carbon ion plans. C-Arc plans with 2 energies per treatment angle, for the employed energy selection heuristic, improved dosimetric quality compared to mono-energetic C-Arc plans, but did not provide the same natural improvement in LETd compared to IMPT. Conclusions For small, centrally located targets C-Arc demonstrates the greatest potential, but feasible plans could also be achieved for more complex cases in this work. Further development is necessary for improving C-Arc delivery efficiency and plan quality toward possible clinical application.

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Dosimetric Validation of a System to Treat Moving Tumors Using Scanned Ion Beams That Are Synchronized With Anatomical Motion

Cited by 7 publications

References 43 publications

Considerations for Upright Particle Therapy Patient Positioning and Associated Image Guidance

Considerations for Upright Particle Therapy Patient Positioning and Associated Image Guidance

The Influence of Motion on the Delivery Accuracy When Comparing Actively Scanned Carbon Ions versus Protons at a Synchrotron-Based Radiotherapy Facility

Exploring energy selection methods for robust biologically optimized carbon ion arc for head&neck cancer patients

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