TU-C-224A-02: Aperture-Based Beam Delivery for Intensity Modulated Proton Therapy

Abstract Background This study investigated the feasibility and potential clinical benefit of utilizing a new proton treatment technique: Spot-scanning Proton Arc (SPArc) therapy for left-sided breast cancer irradiation to further reduce radiation dose to healthy tissue and mitigate the probability of normal tissue complications compared to conventional Intensity Modulated Proton Therapy(IMPT). Methods Eight patients diagnosed with left-sided breast cancer and treated with breast-preserving surgery followed by whole breast irradiation without regional nodal irradiation were included in this retrospective planning. Two proton treatment plans were generated for each patient: vertical intensity-modulated proton therapy used for clinical treatment (vIMPT, gantry angle 10°-30°) and SPArc for comparison purpose. Both SPArc and vIMPT plans were optimized using the robust optimization of ± 3.5% range and 5 mm setup uncertainties. Root-mean-square deviation dose (RMSD) volume histograms were used for plan robustness evaluation. All dosimetric results were evaluated based on dose-volume histograms (DVH), and the interplay effect was evaluated based on the accumulation of single-fraction 4D dynamic dose on CT50. The treatment beam delivery time was simulated based on a gantry rotation with energy-layer-switching-time (ELST) from 0.2 to 5 s. Results The average D1 to the heart and LAD were reduced to 53.63 cGy and 82.25 cGy compared with vIMPT 110.38 cGy (p = 0.001) and 170.38 cGy (p = 0.001), respectively. The average V5Gy and V20Gy of ipsilateral lung was reduced to 16.77% and 3.07% compared to vIMPT 25.56% (p = 0.001) and 4.68% (p = 0.003). Skin3mm mean and maximum dose was reduced to 3999.38 cGy and 4395.63 cGy compared to vIMPT 4104.25 cGy (p = 0.039) and 4411.63 cGy (p = 0.043), respectively. A significant relative risk reduction (RNTCP = NTCPSPArc / NTCPvIMPT) for organs at risk (OARs) was obtained with SPArc ranging from 0.61 to 0.86 depending on the clinical endpoint. The RMSD Volume Histogram(RVH) analysis shows SPArc provided better plan robustness in OARs sparing, including the heart, LAD, ipsilateral lung, and skin. The average estimated treatment beam delivery times were comparable to vIMPT plans when the ELST is about 0.5 s. Conclusion SPArc technique can further reduce dose delivered to OARs and the probability of normal tissue complications in patients treated for left-sided breast cancer.

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Feasibility study: Spot-scanning Proton Arc therapy (SPArc) for left-sided whole breast radiotherapy

10.21203/rs.3.rs-38925/v2 ◽

2020 ◽

Author(s):

Sheng Chang ◽

Gang Liu ◽

Lewei Zhao ◽

Joshua T Dilworth ◽

Weili Zheng ◽

...

Keyword(s):

Proton Therapy ◽

Normal Tissue ◽

Breast Radiotherapy ◽

Ipsilateral Lung ◽

Intensity Modulated Proton Therapy ◽

Intensity Modulated ◽

Spot Scanning ◽

Whole Breast Radiotherapy ◽

Proton Treatment ◽

Beam Delivery

Abstract Background : This study investigated the feasibility and potential clinical benefit of utilizing a new proton treatment technique: Spot-scanning Proton Arc (SPArc) therapy for left-sided whole breast radiotherapy (WBRT) to further reduce radiation dose to healthy tissue and mitigate the probability of normal tissue complications compared to conventional Intensity Modulated Proton Therapy (IMPT). Methods : Eight patients diagnosed with left-sided breast cancer and treated with breast-preserving surgery followed by whole breast irradiation without regional nodal irradiation were included in this retrospective planning. Two proton treatment plans were generated for each patient: vertical intensity-modulated proton therapy used for clinical treatment (vIMPT, gantry angle 10°-30°) and SPArc for comparison purpose. Both SPArc and vIMPT plans were optimized using the robust optimization of ±3.5% range and 5mm setup uncertainties. Root-mean-square deviation dose (RMSD) volume histogram s were used for plan robustness evaluation. All dosimetric results were evaluated based on dose-volume histograms (DVH), and the interplay effect was evaluated based on the accumulation of single-fraction 4D dynamic dose on CT50. The treatment beam delivery time was simulated based on a gantry rotation with energy-layer-switching-time (ELST) from 0.2 to 5s. Results: The average D1 to the heart and LAD were reduced to 53.63cGy and 82.25cGy compared with vIMPT 110.38cGy (p = 0.001) and 170.38cGy (p = 0.001), respectively. The average V5Gy and V20Gy of ipsilateral lung was reduced to 16.77% and 3.07% compared to vIMPT 25.56% (p = 0.001) and 4.68% (p = 0.003). Skin3mm mean and maximum dose were reduced to 3999.38cGy and 4395.63cGy compared to vIMPT 4104.25cGy (p=0.039) and 4411.63cGy (p=0.043), respectively. A significant relative risk reduction (RNTCP = NTCP SPArc / NTCP vIMPT ) for organs at risk (OARs) was obtained with SPArc ranging from 0.61 to 0.86 depending on the clinical endpoint. The RMSD Volume Histogram (RVH) analysis shows SPArc provided better plan robustness in OARs sparing, including the heart, LAD, ipsilateral lung, and skin. The average estimated treatment beam delivery times were comparable to vIMPT plans when the ELST is about 0.5s. Conclusion: SPArc technique can further reduce dose delivered to OARs and the probability of normal tissue complications in patient treated for left-sided WBRT.

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Exploring the advantages of intensity-modulated proton therapy: experimental validation of biological effects using two different beam intensity-modulation patterns

Scientific Reports ◽

10.1038/s41598-020-60246-5 ◽

2020 ◽

Vol 10 (1) ◽

Cited By ~ 2

Author(s):

Duo Ma ◽

Lawrence Bronk ◽

Matthew Kerr ◽

Mary Sobieski ◽

Mei Chen ◽

...

Keyword(s):

Proton Therapy ◽

Biological Effects ◽

High Energy ◽

Intensity Modulation ◽

Low Energy ◽

Delivery Strategy ◽

Intensity Modulated Proton Therapy ◽

Intensity Modulated ◽

Flat Dose ◽

Beam Delivery

Abstract In current treatment plans of intensity-modulated proton therapy, high-energy beams are usually assigned larger weights than low-energy beams. Using this form of beam delivery strategy cannot effectively use the biological advantages of low-energy and high-linear energy transfer (LET) protons present within the Bragg peak. However, the planning optimizer can be adjusted to alter the intensity of each beamlet, thus maintaining an identical target dose while increasing the weights of low-energy beams to elevate the LET therein. The objective of this study was to experimentally validate the enhanced biological effects using a novel beam delivery strategy with elevated LET. We used Monte Carlo and optimization algorithms to generate two different intensity-modulation patterns, namely to form a downslope and a flat dose field in the target. We spatially mapped the biological effects using high-content automated assays by employing an upgraded biophysical system with improved accuracy and precision of collected data. In vitro results in cancer cells show that using two opposed downslope fields results in a more biologically effective dose, which may have the clinical potential to increase the therapeutic index of proton therapy.

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Feasibility study: spot-scanning proton arc therapy (SPArc) for left-sided whole breast radiotherapy

Radiation Oncology ◽

10.1186/s13014-020-01676-3 ◽

2020 ◽

Vol 15 (1) ◽

Author(s):

Sheng Chang ◽

Gang Liu ◽

Lewei Zhao ◽

Joshua T. Dilworth ◽

Weili Zheng ◽

...

Keyword(s):

Proton Therapy ◽

Normal Tissue ◽

Breast Radiotherapy ◽

Ipsilateral Lung ◽

Intensity Modulated Proton Therapy ◽

Intensity Modulated ◽

Spot Scanning ◽

Whole Breast Radiotherapy ◽

Proton Treatment ◽

Beam Delivery

Abstract Background This study investigated the feasibility and potential clinical benefit of utilizing a new proton treatment technique: Spot-scanning proton arc (SPArc) therapy for left-sided whole breast radiotherapy (WBRT) to further reduce radiation dose to healthy tissue and mitigate the probability of normal tissue complications compared to conventional intensity modulated proton therapy (IMPT). Methods Eight patients diagnosed with left-sided breast cancer and treated with breast-preserving surgery followed by whole breast irradiation without regional nodal irradiation were included in this retrospective planning. Two proton treatment plans were generated for each patient: vertical intensity-modulated proton therapy used for clinical treatment (vIMPT, gantry angle 10°–30°) and SPArc for comparison purpose. Both SPArc and vIMPT plans were optimized using the robust optimization of ± 3.5% range and 5 mm setup uncertainties. Root-mean-square deviation dose (RMSD) volume histograms were used for plan robustness evaluation. All dosimetric results were evaluated based on dose-volume histograms (DVH), and the interplay effect was evaluated based on the accumulation of single-fraction 4D dynamic dose on CT50. The treatment beam delivery time was simulated based on a gantry rotation with energy-layer-switching-time (ELST) from 0.2 to 5 s. Results The average D1 to the heart and LAD were reduced to 53.63 cGy and 82.25 cGy compared with vIMPT 110.38 cGy (p = 0.001) and 170.38 cGy (p = 0.001), respectively. The average V5Gy and V20Gy of ipsilateral lung was reduced to 16.77% and 3.07% compared to vIMPT 25.56% (p = 0.001) and 4.68% (p = 0.003). Skin3mm mean and maximum dose were reduced to 3999.38 cGy and 4395.63 cGy compared to vIMPT 4104.25 cGy (p = 0.039) and 4411.63 cGy (p = 0.043), respectively. A significant relative risk reduction (RNTCP = NTCPSPArc/NTCPvIMPT) for organs at risk (OARs) was obtained with SPArc ranging from 0.61 to 0.86 depending on the clinical endpoint. The RMSD volume histogram (RVH) analysis shows SPArc provided better plan robustness in OARs sparing, including the heart, LAD, ipsilateral lung, and skin. The average estimated treatment beam delivery times were comparable to vIMPT plans when the ELST is about 0.5 s. Conclusion SPArc technique can further reduce dose delivered to OARs and the probability of normal tissue complications in patients treated for left-sided WBRT.

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Optimization of Beam Parameters and Treatment Planning for Intensity Modulated Proton Therapy

Technology in Cancer Research & Treatment ◽

10.1177/153303460300200508 ◽

2003 ◽

Vol 2 (5) ◽

pp. 437-444 ◽

Cited By ~ 31

Author(s):

Alexei Trofimov ◽

Thomas Bortfeld

Keyword(s):

Treatment Planning ◽

Delivery System ◽

Proton Therapy ◽

Target Volume ◽

Pencil Beam ◽

Ongoing Research ◽

Intensity Modulated Proton Therapy ◽

Intensity Modulated ◽

Beam Delivery ◽

Proton Dose

One of the objectives of the ongoing research and development work at the Northeast Proton Therapy Center (NPTC) in Boston is to perform optimized intensity modulated proton therapy (IMPT) treatments. Such treatments may be delivered by magnetically scanning a narrow proton pencil beam across the target volume, while both the scanning speed and the intensity of the beam are modulated. Localization of the proton dose in space allows one to yield dose distributions that are highly conformal to the target volume, thus minimizing the dose delivered to the surrounding healthy tissue. The aim of the current research is to determine technically optimal and clinically relevant specifications for the scanned beam delivery system, which is being developed in collaboration with Ion Beam Applications (IBA); and to create a link between the treatment planning and the beam delivery. IMPT treatment planning is performed for patient cases treated at the NPTC, with KonRad Pro software developed at the German Cancer Research Center (DKFZ). For the IMPT delivery, the proton intensity maps, optimized for discrete pencil beam spots, need to be translated into continuous scanning patterns. At the same time it is necessary to minimize the discrepancy between the planned and delivered doses which may result from such conversion, as well as from the technical limitations of the delivery system. Possibilities have been investigated for improving the proton dose conformity by optimizing the beam and scanning nozzle parameters, and by taking the specifics and limitations of the system into account in the treatment planning stage.

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Early Clinical Outcomes of Intensity Modulated Radiation Therapy/Intensity Modulated Proton Therapy Combination in Comparison with Intensity Modulated Radiation Therapy Alone in Oropharynx Cancer Patients

Cancers ◽

10.3390/cancers13071549 ◽

2021 ◽

Vol 13 (7) ◽

pp. 1549

Author(s):

Han Gyul Yoon ◽

Yong Chan Ahn ◽

Dongryul Oh ◽

Jae Myoung Noh ◽

Seung Gyu Park ◽

...

Keyword(s):

Radiation Therapy ◽

Proton Therapy ◽

Intensity Modulated Radiation Therapy ◽

Combination Group ◽

Intensity Modulated Proton Therapy ◽

Oropharynx Cancer ◽

Intensity Modulated ◽

Before And After ◽

Grade 3 ◽

Early Clinical Outcomes

Purpose: To report the early clinical outcomes of combining intensity-modulated radiation therapy (IMRT) and intensity-modulated proton therapy (IMPT) in comparison with IMRT alone in treating oropharynx cancer (OPC) patients. Materials and Methods: The medical records of 148 OPC patients who underwent definitive radiotherapy (RT) with concurrent systemic therapy, from January 2016 till December 2019 at Samsung Medical Center, were retrospectively reviewed. During the 5.5 weeks’ RT course, the initial 16 (or 18) fractions were delivered by IMRT in all patients, and the subsequent 12 (or 10) fractions were either by IMRT in 81 patients (IMRT only) or by IMPT in 67 (IMRT/IMPT combination), respectively, based on comparison of adaptive re-plan profiles and availability of equipment. Propensity-score matching (PSM) was done on 76 patients (38 from each group) for comparative analyses. Results: With the median follow-up of 24.7 months, there was no significant difference in overall survival and progression free survival between groups, both before and after PSM. Before PSM, the IMRT/IMPT combination group experienced grade ≥ 3 acute toxicities less frequently: mucositis in 37.0% and 13.4% (p < 0.001); and analgesic quantification algorithm (AQA) in 37.0% and 19.4% (p = 0.019), respectively. The same trends were observed after PSM: mucositis in 39.5% and 15.8% (p = 0.021); and AQA in 47.4% and 21.1% (p = 0.016), respectively. In multivariate logistic regression, grade ≥ 3 mucositis was significantly less frequent in the IMRT/IMPT combination group, both before and after PSM (p = 0.027 and 0.024, respectively). AQA score ≥ 3 was also less frequent in the IMRT/IMPT combination group, both before and after PSM (p = 0.085 and 0.018, respectively). Conclusions: In treating the OPC patients, with comparable early oncologic outcomes, more favorable acute toxicity profiles were achieved following IMRT/IMPT combination than IMRT alone.

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