3D printed 2D range modulators preserve radiation quality on a microdosimetric scale in proton and carbon ion beams

Barna, Sandra; Meouchi, Cynthia; Resch, Andreas; Magrin, Giulio; Georg, Dietmar

doi:10.1016/j.radonc.2023.109525

Cited by 3 publications

(3 citation statements)

References 28 publications

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“…Still, a few PT applications for 3D-printed (anthropomorphic) phantoms have been presented, and some have reported a mismatch of CTpredicted SPR for the materials used [15,20]. Furthermore, recent publications have shown good results concerning 3D printing applications for particle beam modulation [31][32][33][34][35].…”

Section: Discussionmentioning

confidence: 99%

“…In addition to the constant shape of the lateral beam profiles, this is good evidence that the 3D prints do not deteriorate beam quality. Recent findings by Barna et al further showed that 3D-printed structures even preserved radiation quality on a microdosimetric scale [31]. Overall, the SLA prints were not considered tissue surrogates because of their high SPR and poor prediction accuracy but can be recommended for, for example, patient-specific boluses using a bulk override to avoid reported FDM-printing inaccuracy and heterogeneity [36].…”

Section: Discussionmentioning

confidence: 99%

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Dosimetric characteristics of 3D-printed and epoxy-based materials for particle therapy phantoms

Brunner,

Langgartner,

Danhel

et al. 2024

Front. Phys.

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Objective3D printing has seen use in many fields of imaging and radiation oncology, but applications in (anthropomorphic) phantoms, especially for particle therapy, are still lacking. The aim of this work was to characterize various available 3D printing methods and epoxy-based materials with the specific goal of identifying suitable tissue surrogates for dosimetry applications in particle therapy.Methods3D-printed and epoxy-based mixtures of varying ratios combining epoxy resin, bone meal, and polyethylene powder were scanned in a single-energy computed tomography (CT), a dual-energy CT, and a µCT scanner. Their CT-predicted attenuation was compared to measurements in a 148.2 MeV proton and 284.7 MeV/u carbon ion beam. The sample homogeneity was evaluated in the respective CT images and in the carbon beam, additionally via widening of the Bragg peak. To assess long-term stability attenuation, size and weight measurements were repeated after 6–12 months.ResultsFour 3D-printed materials, acrylonitrile butadiene styrene polylactic acid, fused deposition modeling printed nylon, and selective laser sintering printed nylon, and various ratios of epoxy-based mixtures were found to be suitable tissue surrogates. The materials’ predicted stopping power ratio matched the measured stopping power ratio within 3% for all investigated CT machines and protocols, except for µCT scans employing cone beam CT technology. The heterogeneity of the suitable surrogate samples was adequate, with a maximum Bragg peak width increase of 11.5 ± 2.5%. The repeat measurements showed no signs of degradation after 6–12 months.ConclusionWe identified surrogates for soft tissue and low- to medium-density bone among the investigated materials. This allows low-cost, adaptable phantoms to be built for quality assurance and end-to-end tests for particle therapy.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Dosimetric characteristics of 3D-printed and epoxy-based materials for particle therapy phantoms

Brunner,

Langgartner,

Danhel

et al. 2024

Front. Phys.

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“…The weights of individual beamlets were then optimised using a MATLAB script to achieve the required STV profiles (<0.5% uniformity in the SOBP region) (Romano et al 2019). We assume this is representative of the dose distributions from the commercial TPSs as the local spectrum will be close enough (Barna et al 2023). Corrections calculated analytically included k z, cal which is the correction factor for the reference distance from the beam and k ripple which corrects for the degree of ripple in the flat region of the SOBP where measurements were made.…”

Section: Monte Carlo and Analytical Derived Correctionsmentioning

confidence: 99%

A portable primary-standard level graphite calorimeter for absolute dosimetry in clinical pencil beam scanning proton beams

et al. 2023

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Objective: To report the use of a portable primary standard level graphite calorimeter for direct dose determination in clinical pencil beam scanning proton beams, which forms part of the recommendations of the proposed Institute of Physics and Engineering in Medicine (IPEM) Code of Practice (CoP) for proton therapy dosimetry.Approach: The Primary Standard Proton Calorimeter (PSPC) was developed at the National Physical Laboratory (NPL) and measurements were performed at four clinical proton therapy facilities that use pencil beam scanning for beam delivery. Correction factors for the presence of impurities and vacuum gaps were calculated and applied, as well as dose conversion factors to obtain dose-to-water. Measurements were performed in the middle of 10×10×10 cm3 homogeneous dose volumes, centred at 10.0, 15.0 and 25.0 g∙cm-2 depth in water. The absorbed dose to water determined with the calorimeter was compared to the dose obtained using PTW Roos-type ionisation chambers calibrated in terms of absorbed dose to water in 60Co applying the recommendations in the IAEA TRS-398 CoP.Main results: The relative dose difference between the two protocols varied between 0.4% and 2.1% depending on the facility. The reported overall uncertainty in the determination of absorbed dose-to-water using the calorimeter is 0.9% (k=1), which corresponds to a significant reduction of uncertainty in comparison with the TRS-398 CoP (currently with an uncertainty equal or larger than 2.0% (k=1) for proton beams).Significance: The establishment of a purpose-built primary standard and associated CoP will considerably reduce the uncertainty of the absorbed dose-to-water determination and ensure improved accuracy and consistency in the dose delivered to patients treated with proton therapy and bring proton reference dosimetry uncertainty in line with megavoltage photon radiotherapy.

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Passive SOBP generation from a static proton pencil beam using 3D-printed range modulators for FLASH experiments

et al. 2023

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The University Proton Therapy facility in Dresden (UPTD), Germany, is equipped with an experimental room with a beamline providing a static pencil beam. High proton beam currents can be achieved at this beamline which makes it suitable for FLASH experiments. However, the established experimental setup uses only the entrance channel of the proton Bragg curve. In this work, a set of 3D-printed range modulators designed to generate spread out Bragg peaks (SOBPs) for radiobiological experiments at ultra-high dose rate at this beamline is described. A new method to optimize range modulators specifically for the case of a static pencil beam based on the central depth dose profile is introduced. Modulators for two different irradiation setups were produced and characterized experimentally by measurements of lateral and depth dose distributions using different detectors. In addition, Monte Carlo simulations were performed to assess profiles of the dose averaged linear energy transfer (LETD) in water. These newly produced range modulators will allow future proton FLASH experiments in the SOBP at UPTD with two different experimental setups.

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3D printed 2D range modulators preserve radiation quality on a microdosimetric scale in proton and carbon ion beams

Cited by 3 publications

References 28 publications

Dosimetric characteristics of 3D-printed and epoxy-based materials for particle therapy phantoms

Dosimetric characteristics of 3D-printed and epoxy-based materials for particle therapy phantoms

A portable primary-standard level graphite calorimeter for absolute dosimetry in clinical pencil beam scanning proton beams

Passive SOBP generation from a static proton pencil beam using 3D-printed range modulators for FLASH experiments

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