Accurate proton treatment planning for pencil beam crossing titanium fixation implants

Righetto, Roberto; Clemens, Luis Pazos; Lorentini, Stefano; Fracchiolla, F.; Algranati, Carlo; Tommasino, Francesco; Dionisi, Francesco; Cianchetti, M.; Schwarz, Marco; Farace, Paolo

doi:10.1016/j.ejmp.2020.01.003

Cited by 13 publications

(20 citation statements)

References 20 publications

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“…This disadvantageous feature of PB algorithms lies in its nature and cannot be optimized via improvements of the PB algorithms implementation. Similar uncertainties of 10-20% for PB algorithm was also reported Righetto et al [17], however with the very dense materials, more specifically titanium. The MC calculations proved to be a reliable approach to compute the dose in patients with titanium implants.…”

Section: Discussionsupporting

confidence: 84%

“…The kernel accounts for all possible radiation effects arising from the interaction of protons, such as scattering and absorption of secondary electron. Differently to the PB algorithm, the MC takes into account the physics of particle interactions on a particle by particle basis using theoretical models or experimental cross section data for electromagnetic and nuclear interactions [14][15][16][17][18]. The implemented version of the MC engine in the RaySearch TPS comes along with approximations for the transport mechanisms and electromagnetic processes.…”

Section: Treatment Planning System and Dose Calculation Algorithmsmentioning

confidence: 99%

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Experimental benchmarking of RayStation proton dose calculation algorithms inside and outside the target region in heterogeneous phantom geometries

et al. 2020

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The aim of the presented study was to complement existing literature on benchmarking proton dose by comparing dose calculations with experimental measurements in heterogeneous phantom. Points of interest inside and outside the target were considered to quantify the magnitude of calculation uncertainties in current and previous proton therapy practice that might especially have an impact on the dose in organs at risk (OARs). Methods: The RayStation treatment planning system (RaySearch Laboratories), offering two dose calculation algorithms for pencil beam scanning in proton therapy, i.e., Pencil Beam (PB) and Monte Carlo (MC), was utilized. Treatment plans for a target located behind the interface of the heterogeneous tissues were generated. Dose measurements within and behind the target were performed in a water phantom with embedded slabs of various tissue equivalent materials and 24 PinPoint ionization chambers (PTW). In total 12 test configurations encompassing two different target depths, oblique beam incidence of 30 degrees and range shifter, were considered. Results: PB and MC calculated doses agreed equally well with the measurements for all test geometries within the target, including the range shifter (mean dose differences ± 3%). Outside the target, the maximum dose difference of 9% (19%) was observed for MC (PB) for the oblique beam incidence and inserted range shifter. Conclusion:The accuracy of MC dose algorithm was superior compared to the PB algorithm, especially outside the target volumes. MC based dose calculation should therefore be preferred in treatment scenarios with heterogeneities, especially to reduce clinically relevant uncertainties for OARs.

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Section: Discussionsupporting

confidence: 84%

Section: Treatment Planning System and Dose Calculation Algorithmsmentioning

confidence: 99%

Experimental benchmarking of RayStation proton dose calculation algorithms inside and outside the target region in heterogeneous phantom geometries

et al. 2020

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“…In the clinical H&N study with dental implants, planned dose distributions to a neck node were calculated on CT art and CT cor , and minor differences were observed. On the other hand, in a phantom (Gammex Inc., Middleton, WI, USA) study with a Ti implant, Righetto et al reported that the calculated proton range using WET was overestimated more on the CT cor after O‐MAR application than on both CT art and CT ref 63 . The reference was obtained using stopping power values from the data which were published by NIST (Gaithersburg, MD, USA).…”

Section: Resultsmentioning

confidence: 99%

“…Commercial MAR methods O-MAR, iMAR, Smart MAR & SEMAR 35,[41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57]59,62,63 Standard methods and are used routinely in the clinic. Applicable on a wide range of clinical cases for RT applications.…”

Section: Mar Methods Strength Weaknessmentioning

confidence: 99%

“…The Anisotropic Analytical Algorithm (AAA) 60 and Acuros External Beam (AXB) algorithm 61 that the calculated proton range using WET was overestimated more on the CT cor after O-MAR application than on both CT art and CT ref . 63 The reference was obtained using stopping power values from the data which were published by NIST (Gaithersburg, MD, USA). As a result, ΔWET on CT cor after O-MAR application and CT art were 0.57 cm and 0.16 cm, respectively, when compared with the reference value.…”

Section: Dosimetric Impact Of Commercial Mar Algorithmsmentioning

confidence: 99%

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The application of metal artifact reduction methods on computed tomography scans for radiotherapy applications: A literature review

Puvanasunthararajah

Fontanarosa

Wille

et al. 2021

J Applied Clin Med Phys

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Metal artifact reduction (MAR) methods are used to reduce artifacts from metals or metal components in computed tomography (CT). In radiotherapy (RT), CT is the most used imaging modality for planning, whose quality is often affected by metal artifacts. The aim of this study is to systematically review the impact of MAR methods on CT Hounsfield Unit values, contouring of regions of interest, and dose calculation for RT applications. This systematic review is performed in accordance with the PRISMA guidelines; the PubMed and Web of Science databases were searched using the main keywords "metal artifact reduction", "computed tomography" and "radiotherapy". A total of 382 publications were identified, of which 40 (including one review article) met the inclusion criteria and were included in this review. The selected publications (except for the review article) were grouped into two main categories: commercial MAR methods and research-based MAR methods. Conclusion: The application of MAR methods on CT scans can improve treatment planning quality in RT. However, none of the investigated or proposed MAR methods was completely satisfactory for RT applications because of limitations such as the introduction of other errors (e.g., other artifacts) or image quality degradation (e.g., blurring), and further research is still necessary to overcome these challenges.

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Three‐dimensional dosimetry using multiple‐energy delivery and a single‐layer detector for quality assurance in proton pencil beam scanning

Righetto,

Fogazzi,

Tommasino

et al. 2024

Medical Physics

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BackgroundIn Proton Therapy, the presence of implants along the beam path is known to potentially affect the dose distribution. The way such implants are managed in the planning process can vary in the different treatment planning systems (TPSs) and different centers. A specific validation procedure should be accomplished to verify the accuracy of TPS computation in these conditions and accept the applied process before treating patients.PurposeThe aim of this study is to present a quality assurance (QA) tool in pencil beam scanning proton therapy by a method based on multiple‐energy delivery and a single‐layer two‐dimensional detector and to apply it for verifying three‐dimensional dose computation and correcting CT calibration in the presence of implants.MethodsMultiple‐energy delivery with a single‐layer detector (MESL) acquisitions were performed for 80 energy layers (70‐150MeV), composed of equally weighted pencil beam spots. MESL measures were acquired using a two‐dimensional MatriXX‐IBA detector. A transformation of the energy modulation to spatial modulation was obtained by using the power‐law relationship of initial energy and range. The setup design involved a reference configuration, allowing to compensate for potential offsets, and the same configuration with an additional phantom to be measured. Both setups were imaged by a CT scanner, and the dose was computed by the TPS. The comparison of TPS‐computed and MESL‐measured data of the phantom was performed by producing a 2D map of range‐error. For testing the procedure, plastic slabs and rods made of tissue equivalent materials (TEMs), with known water equivalent path length (WEPL), were used. Range error mapping was then applied to verify dose computation with a titanium cylinder and a titanium implant. Numerical procedures were obtained by modifying at the TPS the segmented volume, or the value in the CT calibration curve for the titanium objects. The optimal values were then determined by identifying the one that minimizes residual range error.ResultsThe results of the consistency test on the plastic slabs and the TEM rods showed differences between measured and expected WEPL below 1%, confirming the reliability of the method and the energy‐spatial transformation. In the titanium cylinder, the optimal volume and the point in the calibration curve (relative to the titanium saturated value), to be used for TPS simulation is about the real size of the cylinder and the tabulated stopping power value. However, the optimal value to be assigned to the CT calibration curve might depend on the type and shape of the object, as they were different for the cylinder and the implant with screws.ConclusionsThe availability of a QA tool, like the one presented, paves the way for systematic studies of all the parameters that impact computation accuracy, and the methods to improve the accuracy of TPS computation.

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Accurate proton treatment planning for pencil beam crossing titanium fixation implants

Cited by 13 publications

References 20 publications

Experimental benchmarking of RayStation proton dose calculation algorithms inside and outside the target region in heterogeneous phantom geometries

Experimental benchmarking of RayStation proton dose calculation algorithms inside and outside the target region in heterogeneous phantom geometries

The application of metal artifact reduction methods on computed tomography scans for radiotherapy applications: A literature review

Three‐dimensional dosimetry using multiple‐energy delivery and a single‐layer detector for quality assurance in proton pencil beam scanning

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