International Journal of Particle Therapy最新文献

{"title":"Bone Marrow Suppression during Postoperative Radiation for Bladder Cancer and Comparative Benefit of Proton Therapy-Phase 2 Trial Secondary Analysis.","authors":"Robert H Press,&nbsp;Joseph W Shelton,&nbsp;Chao Zhang,&nbsp;Quang Dang,&nbsp;Sibo Tian,&nbsp;Timothy Shu,&nbsp;Crystal S Seldon,&nbsp;Shaakir Hasan,&nbsp;Ashesh B Jani,&nbsp;Jun Zhou,&nbsp;Mark W McDonald","doi":"10.14338/IJPT-21-00003.1","DOIUrl":"https://doi.org/10.14338/IJPT-21-00003.1","url":null,"abstract":"<p><strong>Purpose: </strong>For patients with high-risk bladder cancer (pT3⁺ or N⁺), local regional failure remains a challenge after chemotherapy and cystectomy. An ongoing prospective phase 2 trial (NCT01954173) is examining the role of postoperative photon radiation therapy for high-risk patients using volumetric modulated arc therapy. Proton beam therapy (PBT) may be beneficial in this setting to reduce hematologic toxicity. We evaluated for dosimetric relationships with pelvic bone marrow (PBM) and changes in hematologic counts before and after pelvic radiation therapy and explored the potential of PBT treatment plans to achieve reductions in PBM dose.</p><p><strong>Materials and methods: </strong>All enrolled patients were retrospectively analyzed after pelvic radiation per protocol with 50.4 to 55.8 Gy in 28 to 31 fractions. Comparative PBT plans were generated using pencil-beam scanning and a 3-beam multifield optimization technique. Changes in hematologic nadirs were assessed using paired <i>t</i> test. Correlation of mean nadirs and relative PBM dose levels were assessed using the Pearson correlation coefficient (CC).</p><p><strong>Results: </strong>Eighteen patients with a median age of 70 were analyzed. Mean cell count values after radiation therapy decreased compared with preradiation therapy values for white blood cells (WBCs), absolute neutrophil count (ANC), absolute lymphocyte count (all <i>P</i> < .001), and platelets (<i>P</i> = .03). Increased mean PBM dose was associated with lower nadirs in WBC (Pearson CC -0.593, <i>P</i> = .02), ANC (Pearson CC -0.597, <i>P</i> = .02), and hemoglobin (Pearson CC -0.506, <i>P</i> = .046), whereas the PBM V30 to V40 correlated with lower WBC (Pearson CC -0.512 to -0.618, <i>P</i> < .05), and V20 to V30 correlated with lower ANC (Pearson CC -0.569 to -0.598, <i>P</i> < .04). Comparative proton therapy plans decreased the mean PBM dose from 26.5 Gy to 16.1 Gy (<i>P</i> < .001) and had significant reductions in the volume of PBM receiving doses from 5 to 40 Gy (<i>P</i> < .001).</p><p><strong>Conclusion: </strong>Increased PBM mean dose and V20 to V40 were associated with lower hematologic nadirs. PBT plans reduced PBM dose and may be a valuable strategy to reduce the risk of hematologic toxicity in these patients.</p>","PeriodicalId":36923,"journal":{"name":"International Journal of Particle Therapy","volume":"8 3","pages":"1-10"},"PeriodicalIF":1.7,"publicationDate":"2021-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8768898/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39894933","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Oncologic Outcomes for Head and Neck Skin Malignancies Treated with Protons.","authors":"Jidapa Bridhikitti,&nbsp;Jason K Viehman,&nbsp;W Scott Harmsen,&nbsp;Adam C Amundson,&nbsp;Satomi Shiraishi,&nbsp;Daniel W Mundy,&nbsp;Jean-Claude M Rwigema,&nbsp;Lisa A McGee,&nbsp;Samir H Patel,&nbsp;David M Routman,&nbsp;Scott C Lester,&nbsp;Michelle A Neben-Wittich,&nbsp;Yolanda I Garces,&nbsp;Daniel J Ma,&nbsp;Robert L Foote","doi":"10.14338/IJPT-20-00045.1","DOIUrl":"https://doi.org/10.14338/IJPT-20-00045.1","url":null,"abstract":"<p><strong>Purpose: </strong>Radiation therapy (RT) is the standard treatment for patients with inoperable skin malignancies of the head and neck region (H&N), and as adjuvant treatment post surgery in patients at high risk for local or regional recurrence. This study reports clinical outcomes of intensity-modulated proton therapy (IMPT) for these malignancies.</p><p><strong>Materials and methods: </strong>We retrospectively reviewed cases involving 47 patients with H&N malignancies of the skin (squamous cell, basal cell, melanoma, Merkel cell, angiosarcoma, other) who underwent IMPT for curative intent between July 2016 and July 2019. Overall survival was estimated via Kaplan-Meier analysis, and oncologic outcomes were reported as cumulative incidence with death as a competing risk.</p><p><strong>Results: </strong>The 2-year estimated local recurrence rate, regional recurrence rate, local regional recurrence rate, distant metastasis rate, and overall survival were 11.1% (95% confidence interval [CI], 4.1%-30.3%), 4.4% (95% CI, 1.1%-17.4%), 15.5% (95% CI, 7%-34.3%), 23.4% (95% CI, 5.8%-95.5%), and 87.2% (95% CI, 75.7%-100%), respectively. No patient was reported to have a grade 3 or higher adverse event during the last week of treatment or at the 3-month follow-up visit.</p><p><strong>Conclusion: </strong>IMPT is safe and effective in the treatment of skin malignancies of the H&N.</p>","PeriodicalId":36923,"journal":{"name":"International Journal of Particle Therapy","volume":" ","pages":"294-303"},"PeriodicalIF":1.7,"publicationDate":"2021-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8270091/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39202955","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Financial Toxicity in Head and Neck Cancer Patients Treated With Proton Therapy.","authors":"Grace L Smith,&nbsp;Ya-Chen Tina Shih,&nbsp;Steven J Frank","doi":"10.14338/IJPT-20-00054.1","DOIUrl":"https://doi.org/10.14338/IJPT-20-00054.1","url":null,"abstract":"<p><p>Cancer-related financial toxicity impacts head and neck cancer patients and survivors. With increasing use of proton therapy as a curative treatment for head and neck cancer, the multifaceted financial and economic implications of proton therapy-dimensions of \"financial toxicity\"-need to be addressed. Herein, we identify knowledge gaps and potential solutions related to the problem of financial toxicity. To date, while cost-effectiveness analysis has been used to assess the value of proton therapy for head and neck cancer, it may not fully incorporate empiric comparisons of patients' and survivors' lost productivity and disability after treatment. A cost-of-illness framework for evaluation could address this gap, thereby more comprehensively identifying the value of proton therapy and distinctly incorporating a measurable aspect of financial toxicity in evaluation. Overall, financial toxicity burdens remain understudied in head and neck cancer patients from a patient-centered perspective. Systematic, validated, and accurate measurement of financial toxicity in patients receiving proton therapy is needed, especially relative to conventional photon-based strategies. This will enrich the evidence base for optimal selection and rationale for payer coverage of available treatment options for head and neck cancer patients. In the setting of cancer care delivery, a combination of conducting proactive screening for financial toxicity in patients selected for proton therapy, initiating early financial navigation in vulnerable patients, engaging stakeholders, improving oncology provider team cost communication, expanding policies to promote price transparency, and expanding insurance coverage for proton therapy are critical practices to mitigate financial toxicity in head and neck cancer patients.</p>","PeriodicalId":36923,"journal":{"name":"International Journal of Particle Therapy","volume":" ","pages":"366-373"},"PeriodicalIF":1.7,"publicationDate":"2021-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8270089/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39202962","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Intensity-Modulated Proton Therapy (IMPT) Treatment of Angiosarcoma of the Face and Scalp.","authors":"Ashley Hunzeker,&nbsp;Daniel W Mundy,&nbsp;Jiasen Ma,&nbsp;Trey C Mullikin,&nbsp;Robert L Foote","doi":"10.14338/IJPT-D-20-00048.1","DOIUrl":"https://doi.org/10.14338/IJPT-D-20-00048.1","url":null,"abstract":"<p><strong>Purpose: </strong>To successfully plan and treat a patient with diffuse angiosarcoma involving the face and scalp with intensity-modulated proton therapy (IMPT) before surgical resection.</p><p><strong>Materials and methods: </strong>A patient presented to the radiation oncology department for preoperative treatment of an angiosarcoma diffusely involving the face and scalp. A 4-field IMPT technique was used to create a homogeneous dose distribution to the entire target volume while sparing underlying critical structures from toxicity and low-dose spread. A custom Monte Carlo optimizer was necessary to achieve treatment goals. Biological dose was evaluated with a linear energy transfer-based biological enhancement model. Robustness criteria were evaluated per department standard. The patient was successfully planned and treated according to clinical goals.</p><p><strong>Results: </strong>The patient successfully completed the course of IMPT and was able to undergo surgical resection. Pathology indicated no presence of angiosarcoma.</p><p><strong>Conclusion: </strong>IMPT using a custom Monte Carlo optimizer is a suitable radiation therapy treatment option for patients with diffuse angiosarcoma of the scalp and face.</p>","PeriodicalId":36923,"journal":{"name":"International Journal of Particle Therapy","volume":" ","pages":"304-310"},"PeriodicalIF":1.7,"publicationDate":"2021-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8270084/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39202956","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Methodologies to Increase the Level of Evidence of Real-life Proton Therapy in Head and Neck Tumors.","authors":"Francesco Dionisi,&nbsp;Lamberto Widesott,&nbsp;Marco Van Vulpen,&nbsp;Clifton David Fuller,&nbsp;Rocco Frondizi,&nbsp;Marco Meneguzzo,&nbsp;Pierre Blanchard,&nbsp;Maurizio Amichetti,&nbsp;Giuseppe Sanguineti","doi":"10.14338/IJPT-20-00051.1","DOIUrl":"https://doi.org/10.14338/IJPT-20-00051.1","url":null,"abstract":"<p><p>This review aims to present and assess available and new methodologies to increase the clinical evidence of proton therapy data for patients with head and neck cancer. Despite the increasing number of scientific reports showing the feasibility and effectiveness of proton therapy in head and neck cancer, clinical evidence on the potential benefits of its use remains low for several reasons. In this article, the pros and cons of consolidated and new methodologies in this setting such as randomized clinical trials, the model-based approach, and the use of prospective multicentric registries will be detailed.</p>","PeriodicalId":36923,"journal":{"name":"International Journal of Particle Therapy","volume":" ","pages":"328-338"},"PeriodicalIF":1.7,"publicationDate":"2021-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8270108/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39202959","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Review of Particle Therapy for Skull Base Tumors: Modern Considerations and Future Directions.","authors":"Eugen B Hug,&nbsp;Maciej Pelak,&nbsp;Steven J Frank,&nbsp;Piero Fossati","doi":"10.14338/IJPT-20-00083","DOIUrl":"https://doi.org/10.14338/IJPT-20-00083","url":null,"abstract":"<p><p>Skull base tumors constitute one of the established indications for particle therapy, specifically proton therapy. However, a number of prognostic factors, practical clinical management issues, and the emerging role of carbon ion therapy remain subjects of active clinical investigation. This review summarizes these topics, assesses the present status, and reflects on future research directions focusing on the management of chordomas, one of the most aggressive skull base tumors. In addition, the role of particle therapy for benign tumors of the skull base, including pituitary adenoma and acoustic neuroma, is reviewed.</p>","PeriodicalId":36923,"journal":{"name":"International Journal of Particle Therapy","volume":" ","pages":"168-178"},"PeriodicalIF":1.7,"publicationDate":"2021-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8270106/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39204503","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Clinical Outcomes Following Dose-Escalated Proton Therapy for Skull-Base Chordoma.","authors":"Adam L Holtzman,&nbsp;Ronny L Rotondo,&nbsp;Michael S Rutenberg,&nbsp;Daniel J Indelicato,&nbsp;Alexandra De Leo,&nbsp;Dinesh Rao,&nbsp;Jeet Patel,&nbsp;Christopher G Morris,&nbsp;William M Mendenhall","doi":"10.14338/IJPT-20-00066.1","DOIUrl":"https://doi.org/10.14338/IJPT-20-00066.1","url":null,"abstract":"<p><strong>Purpose: </strong>To evaluate the effectiveness of external-beam proton therapy (PT) on local control and survival in patients with skull-base chordoma.</p><p><strong>Materials and methods: </strong>We reviewed the medical records of patients with skull-base chordoma treated with definitive or adjuvant high-dose PT and updated their follow-up when feasible. We assessed overall survival, disease-specific survival, local control, and freedom from distant metastasis. Radiotherapy toxicities were scored using the Common Terminology Criteria for Adverse Events, version 4.0.</p><p><strong>Results: </strong>A total 112 patients were analyzed, of whom 105 (94%) received PT and 7 (6%) received combined proton-photon therapy between 2007 and 2019. Eighty-seven patients (78%) underwent a subtotal resection, 22 (20%) a gross total resection, and 3 (3%) a biopsy alone. The median radiotherapy dose was 73.8 Gy radiobiologic equivalent (GyRBE; range, 69.6-74.4). Ninety patients (80%) had gross disease at radiotherapy and 7 (6%) were treated for locally recurrent disease following surgery. Median follow-up was 4.4 years (range, 0.4-12.6); for living patients, it was 4.6 years (range, 0.4-12.6), and for deceased patients, 4.1 years (range, 1.2-11.2). At 5 years after radiotherapy, the actuarial overall survival, disease-specific survival, local control, and freedom from distant metastasis rates were 78% (n = 87), 83% (n = 93), 74% (n = 83), and 99% (n = 111), respectively. The median time to local progression was 2.4 years (range, 0.8-7). Local control and disease-specific survival by resection status was 95% versus 70% (<i>P</i> = 0.28) and 100% versus 80% (<i>P</i> = 0.06) for gross total, versus subtotal, resection or biopsy alone, respectively. There were no serious acute toxicities (grade ≥ 3) related to radiotherapy.</p><p><strong>Conclusion: </strong>High-dose PT alone or after surgical resection for skull-base chordoma reaffirms the favorable 5-year actuarial local control rate compared with conventional techniques with acceptable late-complication-free survival. Outcomes following gross total resection and adjuvant PT were excellent. Further follow-up of this cohort is necessary to better characterize long-term disease control and late toxicities.</p>","PeriodicalId":36923,"journal":{"name":"International Journal of Particle Therapy","volume":" ","pages":"179-188"},"PeriodicalIF":1.7,"publicationDate":"2021-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8270096/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39204504","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Proton Beam Therapy for Head and Neck Carcinoma of Unknown Primary: Toxicity and Quality of Life.","authors":"Alexander D Sherry,&nbsp;Dario Pasalic,&nbsp;G Brandon Gunn,&nbsp;C David Fuller,&nbsp;Jack Phan,&nbsp;David I Rosenthal,&nbsp;William H Morrison,&nbsp;Erich M Sturgis,&nbsp;Neil D Gross,&nbsp;Maura L Gillison,&nbsp;Renata Ferrarotto,&nbsp;Adel K El-Naggar,&nbsp;Adam S Garden,&nbsp;Steven J Frank","doi":"10.14338/IJPT-20-00034.1","DOIUrl":"https://doi.org/10.14338/IJPT-20-00034.1","url":null,"abstract":"<p><strong>Purpose: </strong>Proton radiation therapy (PRT) may offer dosimetric and clinical benefit in the treatment of head and neck carcinoma of unknown primary (HNCUP). We sought to describe toxicity and quality of life (QOL) in patients with HNCUP treated with PRT.</p><p><strong>Patients and methods: </strong>Toxicity and QOL were prospectively tracked in patients with HNCUP from 2011 to 2019 after institutional review board approval. Patients received PRT to the mucosa of the nasopharynx, oropharynx, and bilateral cervical lymph nodes with sparing of the larynx and hypopharynx. Patient-reported outcomes were tracked with the MD Anderson Symptom Inventory-Head and Neck Module, the Functional Assessment of Cancer Therapy-Head and Neck, the MD Anderson Dysphagia Inventory, and the Xerostomia-Related QOL Scale. Primary study endpoints were the incidence of grade ≥ 3 (G3) toxicity and QOL patterns.</p><p><strong>Results: </strong>Fourteen patients (median follow-up, 2 years) were evaluated. Most patients presented with human papillomavirus-positive disease (n = 12, 86%). Rates of G3 oral mucositis, xerostomia, and dermatitis were 7% (n = 1), 21% (n = 3), and 36% (n = 5), respectively. None required a gastrostomy. During PRT, QOL was reduced relative to baseline and recovered shortly after PRT. At 2 years after PRT, the local regional control, disease-free survival, and overall survival were 100% (among 7 patients at risk), 79% (among 6 patients at risk), and 90% (among 7 patients at risk), respectively.</p><p><strong>Conclusion: </strong>Therefore, PRT for HNCUP was associated with highly favorable dosimetric and clinical outcomes, including minimal oral mucositis, xerostomia, and dysphagia. Toxicity and QOL may be superior with PRT compared with conventional radiation therapy and PRT maintains equivalent oncologic control. Further prospective studies are needed to evaluate late effects and cost-effectiveness.</p>","PeriodicalId":36923,"journal":{"name":"International Journal of Particle Therapy","volume":" ","pages":"234-247"},"PeriodicalIF":1.7,"publicationDate":"2021-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8270080/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39203023","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Review of the Robust Optimization Process and Advances with Monte Carlo in the Proton Therapy Management of Head and Neck Tumors.","authors":"Xiaodong Zhang","doi":"10.14338/IJPT-20-00078.1","DOIUrl":"https://doi.org/10.14338/IJPT-20-00078.1","url":null,"abstract":"<p><p>In intensity-modulated proton therapy, robust optimization processes have been developed to manage uncertainties associated with (1) range, (2) setup, (3) anatomic changes, (4) dose calculation, and (5) biological effects. Here we review our experience using a robust optimization technique that directly incorporates range and setup uncertainties into the optimization process to manage those sources of uncertainty. We also review procedures for implementing adaptive planning to manage the anatomic uncertainties. Finally, we share some early experiences regarding the impact of uncertainties in dose calculation and biological effects, along with techniques to manage and potentially reduce these uncertainties.</p>","PeriodicalId":36923,"journal":{"name":"International Journal of Particle Therapy","volume":" ","pages":"14-24"},"PeriodicalIF":1.7,"publicationDate":"2021-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8270090/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39203650","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Innovations and the Use of Collimators in the Delivery of Pencil Beam Scanning Proton Therapy.","authors":"Daniel E Hyer,&nbsp;Laura C Bennett,&nbsp;Theodore J Geoghegan,&nbsp;Martin Bues,&nbsp;Blake R Smith","doi":"10.14338/IJPT-20-00039.1","DOIUrl":"https://doi.org/10.14338/IJPT-20-00039.1","url":null,"abstract":"<p><strong>Purpose: </strong>The development of collimating technologies has become a recent focus in pencil beam scanning (PBS) proton therapy to improve the target conformity and healthy tissue sparing through field-specific or energy-layer-specific collimation. Given the growing popularity of collimators for low-energy treatments, the purpose of this work was to summarize the recent literature that has focused on the efficacy of collimators for PBS and highlight the development of clinical and preclinical collimators.</p><p><strong>Materials and methods: </strong>The collimators presented in this work were organized into 3 categories: per-field apertures, multileaf collimators (MLCs), and sliding-bar collimators. For each case, the system design and planning methodologies are summarized and intercompared from their existing literature. Energy-specific collimation is still a new paradigm in PBS and the 2 specific collimators tailored toward PBS are presented including the dynamic collimation system (DCS) and the Mevion Adaptive Aperture.</p><p><strong>Results: </strong>Collimation during PBS can improve the target conformity and associated healthy tissue and critical structure avoidance. Between energy-specific collimators and static apertures, static apertures have the poorest dose conformity owing to collimating only the largest projection of a target in the beam's eye view but still provide an improvement over uncollimated treatments. While an external collimator increases secondary neutron production, the benefit of collimating the primary beam appears to outweigh the risk. The greatest benefit has been observed for low- energy treatment sites.</p><p><strong>Conclusion: </strong>The consensus from current literature supports the use of external collimators in PBS under certain conditions, namely low-energy treatments or where the nominal spot size is large. While many recent studies paint a supportive picture, it is also important to understand the limitations of collimation in PBS that are specific to each collimator type. The emergence and paradigm of energy-specific collimation holds many promises for PBS proton therapy.</p>","PeriodicalId":36923,"journal":{"name":"International Journal of Particle Therapy","volume":" ","pages":"73-83"},"PeriodicalIF":1.7,"publicationDate":"2021-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8270095/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39203656","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}