International Journal of Particle Therapy最新文献

{"title":"A Systematic Review of Proton Therapy for the Management of Nasopharyngeal Cancer.","authors":"Anna Lee,&nbsp;Sarin Kitpanit,&nbsp;Marina Chilov,&nbsp;Johannes A Langendijk,&nbsp;Jiade Lu,&nbsp;Nancy Y Lee","doi":"10.14338/IJPT-20-00082.1","DOIUrl":"https://doi.org/10.14338/IJPT-20-00082.1","url":null,"abstract":"<p><strong>Purpose: </strong>With improved technology, more patients with nasopharyngeal cancer (NPC) are receiving definitive treatment with proton therapy, which allows greater sparing of dose to normal tissues without compromising efficacy. As there is no randomized data, the purpose of this study was to systematically review the available literature on proton therapy in this setting, focusing on the toxicity endpoints.</p><p><strong>Materials and methods: </strong>A systematic search using PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines was conducted in 5 databases: PubMed, Embase, SCOPUS, Web of Science, and the Cochrane Central Register of Controlled Trials. A total of 491 studies were found on the topic of NPC and proton therapy. Following independent study selection by 2 investigators, 9 studies were found to have sufficient focus and relevance to be incorporated into the systematic review.</p><p><strong>Results: </strong>All 9 studies were retrospective and examined only NPC patients except for one that also included paranasal sinus cancer. One study was a reirradiation study. Four studies used 3D or double scatter technique, while all others used intensity-modulated proton therapy. Oncologic outcomes were similar to intensity-modulated radiation therapy (IMRT) rates, with 2-year local and regional progression-free survival (LRFS) ranging from 84% to 100%, 2-year progression-free survival (PFS) ranging from 75% to 88.9%, and 2-year overall survival (OS) ranging from 88% to 95% in the up-front setting. Four comparison studies with IMRT found significantly lower feeding tube rates (20% versus 65%, <i>P</i> = .015; and 14% versus 85%, <i>P</i> < .001) with proton therapy as well as lower mucositis (G2 46% versus 70%, <i>P</i> = .019; and G3 11% versus 76%, <i>P</i> = .0002). All other acute and late effects were largely improved with proton therapy but not statistically significant.</p><p><strong>Conclusions: </strong>NPC patients receiving proton therapy maintain good outcomes with improved toxicity profile, likely due to sparing of dose to normal structures. Prospective studies are ongoing to better quantify the magnitude.</p>","PeriodicalId":36923,"journal":{"name":"International Journal of Particle Therapy","volume":" ","pages":"119-130"},"PeriodicalIF":1.7,"publicationDate":"2021-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8270076/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39204500","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 Therapy for Major Salivary Gland Cancer: Clinical Outcomes.","authors":"Alexander N Hanania,&nbsp;Xiaodong Zhang,&nbsp;G Brandon Gunn,&nbsp;David I Rosenthal,&nbsp;Adam S Garden,&nbsp;C David Fuller,&nbsp;Jack Phan,&nbsp;Jay P Reddy,&nbsp;Amy Moreno,&nbsp;Gregory Chronowski,&nbsp;Shalin Shah,&nbsp;Noveen Ausat,&nbsp;Ehab Hanna,&nbsp;Renata Ferrarotto,&nbsp;Steven J Frank","doi":"10.14338/IJPT-20-00044.1","DOIUrl":"https://doi.org/10.14338/IJPT-20-00044.1","url":null,"abstract":"<p><strong>Purpose: </strong>To report clinical outcomes in terms of disease control and toxicity in patients with major salivary gland cancers (SGCs) treated with proton beam therapy.</p><p><strong>Materials and methods: </strong>Clinical and dosimetric characteristics of patients with SGCs treated from August 2011 to February 2020 on an observational, prospective, single-institution protocol were abstracted. Local control and overall survival were calculated by the Kaplan-Meier method. During radiation, weekly assessments of toxicity were obtained, and for patients with ≥ 90 days of follow-up, late toxicity was assessed.</p><p><strong>Results: </strong>Seventy-two patients were identified. Median age was 54 years (range, 23-87 years). Sixty-three patients (88%) received postoperative therapy, and nine patients (12%) were treated definitively. Twenty-six patients (36%) received concurrent chemotherapy. Nine patients (12%) had received prior radiation. All (99%) but one patient received unilateral treatment with a median dose of 64 GyRBE (relative biological effectiveness) (interquartile range [IQR], 60-66), and 53 patients (74%) received intensity-modulated proton therapy with either single-field or multifield optimization. The median follow-up time was 30 months. Two-year local control and overall survival rates were 96% (95% confidence interval [CI] 85%-99%) and 89% (95% CI 76%-95%], respectively. Radiation dermatitis was the predominant grade-3 toxicity (seen in 21% [n = 15] of the patients), and grade ≥ 2 mucositis was rare (14%; n = 10 patients). No late-grade ≥ 3 toxicities were reported.</p><p><strong>Conclusion: </strong>Proton beam therapy for treatment of major SGCs manifests in low rates of acute mucosal toxicity. In addition, the current data suggest a high rate of local control and minimal late toxicity.</p>","PeriodicalId":36923,"journal":{"name":"International Journal of Particle Therapy","volume":" ","pages":"261-272"},"PeriodicalIF":1.7,"publicationDate":"2021-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8270094/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39203025","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 Critical Review of LET-Based Intensity-Modulated Proton Therapy Plan Evaluation and Optimization for Head and Neck Cancer Management.","authors":"Wei Deng,&nbsp;Yunze Yang,&nbsp;Chenbin Liu,&nbsp;Martin Bues,&nbsp;Radhe Mohan,&nbsp;William W Wong,&nbsp;Robert H Foote,&nbsp;Samir H Patel,&nbsp;Wei Liu","doi":"10.14338/IJPT-20-00049.1","DOIUrl":"https://doi.org/10.14338/IJPT-20-00049.1","url":null,"abstract":"<p><p>In this review article, we review the 3 important aspects of linear-energy-transfer (LET) in intensity-modulated proton therapy (IMPT) for head and neck (H&N) cancer management. Accurate LET calculation methods are essential for LET-guided plan evaluation and optimization, which can be calculated either by analytical methods or by Monte Carlo (MC) simulations. Recently, some new 3D analytical approaches to calculate LET accurately and efficiently have been proposed. On the other hand, several fast MC codes have also been developed to speed up the MC simulation by simplifying nonessential physics models and/or using the graphics processor unit (GPU)-acceleration approach. Some concepts related to LET are also briefly summarized including (1) dose-weighted versus fluence-weighted LET; (2) restricted versus unrestricted LET; and (3) microdosimetry versus macrodosimetry. LET-guided plan evaluation has been clinically done in some proton centers. Recently, more and more studies using patient outcomes as the biological endpoint have shown a positive correlation between high LET and adverse events sites, indicating the importance of LET-guided plan evaluation in proton clinics. Various LET-guided plan optimization methods have been proposed to generate proton plans to achieve biologically optimized IMPT plans. Different optimization frameworks were used, including 2-step optimization, 1-step optimization, and worst-case robust optimization. They either indirectly or directly optimize the LET distribution in patients while trying to maintain the same dose distribution and plan robustness. It is important to consider the impact of uncertainties in LET-guided optimization (ie, LET-guided robust optimization) in IMPT, since IMPT is sensitive to uncertainties including both the dose and LET distributions. We believe that the advancement of the LET-guided plan evaluation and optimization will help us exploit the unique biological characteristics of proton beams to improve the therapeutic ratio of IMPT to treat H&N and other cancers.</p>","PeriodicalId":36923,"journal":{"name":"International Journal of Particle Therapy","volume":" ","pages":"36-49"},"PeriodicalIF":1.7,"publicationDate":"2021-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8270082/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39203653","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":"The Role of Particle Therapy in Adenoid Cystic Carcinoma and Mucosal Melanoma of the Head and Neck.","authors":"Daniel K Ebner,&nbsp;Timothy D Malouff,&nbsp;Steven J Frank,&nbsp;Masashi Koto","doi":"10.14338/IJPT-D-20-00076","DOIUrl":"https://doi.org/10.14338/IJPT-D-20-00076","url":null,"abstract":"<p><p>Particle irradiation is suitable for resistant histologies owing to a combination of improved dose delivery with potential radiobiologic advantages in high linear energy transfer radiation. Within the head and neck, adenoid cystic carcinoma and mucosal melanoma are two such histologies, being radioresistant and lying closely proximal to critical structures. Here, we review the use of particle irradiation for adenoid cystic carcinoma and mucosal melanoma of the head and neck.</p>","PeriodicalId":36923,"journal":{"name":"International Journal of Particle Therapy","volume":" ","pages":"273-284"},"PeriodicalIF":1.7,"publicationDate":"2021-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8270088/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39203026","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":"Passively Scattered Proton Therapy for Nonmelanoma Skin Cancer with Clinical Perineural Invasion.","authors":"Curtis M Bryant,&nbsp;Roi Dagan,&nbsp;Adam L Holtzman,&nbsp;Rui Fernandes,&nbsp;Anthony Bunnell,&nbsp;William M Mendenhall","doi":"10.14338/IJPT-20-00062.1","DOIUrl":"https://doi.org/10.14338/IJPT-20-00062.1","url":null,"abstract":"<p><strong>Purpose: </strong>To report our experience with the delivery of passively scattered proton therapy in the management of nonmelanoma skin cancers with clinical perineural invasion.</p><p><strong>Materials and methods: </strong>We reviewed the medical records of patients who received definitive or postoperative proton therapy for nonmelanoma skin cancer with clinical perineural invasion at our institution and updated patient follow-up when possible. All patients were treated with curative intent with or without the delivery of concurrent systemic therapy. We report disease control rates and the rates of late toxicity among this cohort.</p><p><strong>Results: </strong>Twenty-six patients treated between 2008 and 2017 were included in the analysis. Following proton therapy, the 3-year overall, cause-specific, and disease-free survival rates were 59%, 73%, and 60%, respectively. The 3-year local control, local regional control, and distant metastasis-free survival rates were 80%, 65%, and 96%, respectively. On univariate analysis, surgical resection before radiation therapy significantly improved local regional control rates at 3 years (55% versus 86%; <i>P</i> = .04). Grade 3+ late toxicities occurred in 13 patients (50%) and the most common toxicities included grade 3+ keratitis of the ipsilateral eye, which occurred in 4 patients (15%) and grade 3+ brain necrosis in 4 patients (15%).</p><p><strong>Conclusion: </strong>Proton therapy is effective in the management of nonmelanoma skin cancer with clinical perineural invasion. Although disease control and complication rates compare favorably to those previously published for photon-based radiation therapy, the risk for late toxicity is significant and patients should be appropriately counseled.</p>","PeriodicalId":36923,"journal":{"name":"International Journal of Particle Therapy","volume":" ","pages":"285-293"},"PeriodicalIF":1.7,"publicationDate":"2021-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8270093/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39203473","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 Radiotherapy to Reduce Late Complications in Childhood Head and Neck Cancers.","authors":"Michael T Spiotto,&nbsp;Susan L McGovern,&nbsp;G Brandon Gunn,&nbsp;David Grosshans,&nbsp;Mary Frances McAleer,&nbsp;Steven J Frank,&nbsp;Arnold C Paulino","doi":"10.14338/IJPT-20-00069.1","DOIUrl":"https://doi.org/10.14338/IJPT-20-00069.1","url":null,"abstract":"<p><p>In most childhood head and neck cancers, radiotherapy is an essential component of treatment; however, it can be associated with problematic long-term complications. Proton beam therapy is accepted as a preferred radiation modality in pediatric cancers to minimize the late radiation side effects. Given that childhood cancers are a rare and heterogeneous disease, the support for proton therapy comes from risk modeling and a limited number of cohort series. Here, we discuss the role of proton radiotherapy in pediatric head and neck cancers with a focus on reducing radiation toxicities. First, we compare the efficacy and expected toxicities in proton and photon radiotherapy for childhood cancers. Second, we review the benefit of proton radiotherapy in reducing acute and late radiation toxicities, including risks for secondary cancers, craniofacial development, vision, and cognition. Finally, we review the cost effectiveness for proton radiotherapy in pediatric head and neck cancers. This review highlights the benefits of particle radiotherapy for pediatric head and neck cancers to improve the quality of life in cancer survivors, to reduce radiation morbidities, and to maximize efficient health care use.</p>","PeriodicalId":36923,"journal":{"name":"International Journal of Particle Therapy","volume":" ","pages":"155-167"},"PeriodicalIF":1.7,"publicationDate":"2021-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8270100/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39204502","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":"Spot Scanning Proton Therapy for Sinonasal Malignant Tumors.","authors":"Koichiro Nakajima,&nbsp;Hiromitsu Iwata,&nbsp;Yukiko Hattori,&nbsp;Kento Nomura,&nbsp;Shingo Hashimoto,&nbsp;Toshiyuki Toshito,&nbsp;Kensuke Hayashi,&nbsp;Yo Kuroda,&nbsp;Hideo Fukano,&nbsp;Hiroyuki Ogino,&nbsp;Yuta Shibamoto","doi":"10.14338/IJPT-D-20-00043.1","DOIUrl":"https://doi.org/10.14338/IJPT-D-20-00043.1","url":null,"abstract":"<p><strong>Purpose: </strong>Treatment of sinonasal malignant tumors is challenging, and evidence to establish a standard treatment is limited. Our objective was to evaluate the efficacy and safety of spot scanning proton therapy (SSPT) for sinonasal malignant tumors.</p><p><strong>Patients and methods: </strong>We retrospectively analyzed patients with sinonasal malignant tumors (T1-4bN0-2M0) who underwent SSPT between May 2014 and September 2019. The prescription dose was typically either 60 GyRBE in 15 fractions or 60.8 GyRBE in 16 fractions for mucosal melanoma and 70.2 GyRBE in 26 fractions for other histologic subtypes. Endpoints included local control (LC), progression-free survival, overall survival (OS), and incidence of toxicity. Prognostic factors were analyzed using the Kaplan-Meier method and log-rank test.</p><p><strong>Results: </strong>Of 62 enrolled patients, the common histologic subtypes were mucosal melanoma (35%), squamous cell carcinoma (27%), adenoid cystic carcinoma (16%), and olfactory neuroblastoma (10%). Locally advanced stages were common (T3 in 42% and T4 in 53%). Treatment-naïve tumors and postsurgical recurrent tumors accounted for 73% and 27%, respectively. No patient had previous radiotherapy. The median follow-up was 17 months (range, 6-66) for all patients and 21.5 months (range, 6-66) for survivors. The 2-year LC, progression-free survival, and OS rates of all patients were 92%, 50%, and 76%, respectively. Univariate analysis revealed histology as a prognostic factor for OS, being higher in adenoid cystic carcinoma and olfactory neuroblastoma than in other tumors. Sixteen grade ≥3 late toxicities were observed in 12 patients (19%), including 11 events resulting in visual impairment; the most common was cataract. There was 1 grade 4 toxicity, and there were no grade 5 toxicities.</p><p><strong>Conclusion: </strong>SSPT was well tolerated and yielded good LC for sinonasal malignant tumors. Although we consider SSPT to be a leading treatment modality, further studies are required to establish its status as a standard treatment.</p>","PeriodicalId":36923,"journal":{"name":"International Journal of Particle Therapy","volume":" ","pages":"189-199"},"PeriodicalIF":1.7,"publicationDate":"2021-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8270097/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39204505","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":"PTCOG Head and Neck Subcommittee Consensus Guidelines on Particle Therapy for the Management of Head and Neck Tumors.","authors":"Alexander Lin,&nbsp;John H C Chang,&nbsp;Ryan S Grover,&nbsp;Frank J P Hoebers,&nbsp;Upendra Parvathaneni,&nbsp;Samir H Patel,&nbsp;Juliette Thariat,&nbsp;David J Thomson,&nbsp;Johannes A Langendijk,&nbsp;Steven J Frank","doi":"10.14338/IJPT-20-00071.1","DOIUrl":"https://doi.org/10.14338/IJPT-20-00071.1","url":null,"abstract":"<p><strong>Purpose: </strong>Radiation therapy is a standard modality in the treatment for cancers of the head and neck, but is associated with significant short- and long-term side effects. Proton therapy, with its unique physical characteristics, can deliver less dose to normal tissues, resulting in fewer side effects. Proton therapy is currently being used for the treatment of head and neck cancer, with increasing clinical evidence supporting its use. However, barriers to wider adoption include access, cost, and the need for higher-level evidence.</p><p><strong>Methods: </strong>The clinical evidence for the use of proton therapy in the treatment of head and neck cancer are reviewed here, including indications, advantages, and challenges.</p><p><strong>Results: </strong>The Particle Therapy Cooperative Group Head and Neck Subcommittee task group provides consensus guidelines for the use of proton therapy for head and neck cancer.</p><p><strong>Conclusion: </strong>This report can be used as a guide for clinical use, to understand clinical trials, and to inform future research efforts.</p>","PeriodicalId":36923,"journal":{"name":"International Journal of Particle Therapy","volume":" ","pages":"84-94"},"PeriodicalIF":1.7,"publicationDate":"2021-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8270078/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39204498","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":"Dual-Energy Computed Tomography Proton-Dose Calculation with Scripting and Modified Hounsfield Units.","authors":"Anthony Kassaee,&nbsp;Chingyun Cheng,&nbsp;Lingshu Yin,&nbsp;Wei Zou,&nbsp;Taoran Li,&nbsp;Alexander Lin,&nbsp;Samuel Swisher-McClure,&nbsp;John N Lukens,&nbsp;Robert A Lustig,&nbsp;Shannon O'Reilly,&nbsp;Lei Dong,&nbsp;Roni Hytonen Ms,&nbsp;Boon-Keng Kevin Teo","doi":"10.14338/IJPT-20-00075.1","DOIUrl":"https://doi.org/10.14338/IJPT-20-00075.1","url":null,"abstract":"<p><strong>Purpose: </strong>To describe an implementation of dual-energy computed tomography (DECT) for calculation of proton stopping-power ratios (SPRs) in a commercial treatment-planning system. The process for validation and the workflow for safe deployment of DECT is described, using single-energy computed tomography (SECT) as a safety check for DECT dose calculation.</p><p><strong>Materials and methods: </strong>The DECT images were acquired at 80 kVp and 140 kVp and were processed with computed tomography scanner software to derive the electron density and effective atomic number images. Reference SPRs of tissue-equivalent plugs from Gammex (Middleton, Wisconsin) and CIRS (Computerized Imaging Reference Systems, Norfolk, Virginia) electron density phantoms were used for validation and comparison of SECT versus DECT calculated through the Eclipse treatment planning system (Varian Medical Systems, Palo Alto, California) application programming interface scripting tool. An in-house software was also used to create DECT SPR computed tomography images for comparison with the script output. In the workflow, using the Eclipse system application programming interface script, clinical plans were optimized with the SECT image set and then forward-calculated with the DECT SPR for the final dose distribution. In a second workflow, the plans were optimized using DECT SPR with reduced range-uncertainty margins.</p><p><strong>Results: </strong>For the Gammex phantom, the root mean square error in SPR was 1.08% for DECT versus 2.29% for SECT for 10 tissue-surrogates, excluding the lung. For the CIRS Phantom, the corresponding results were 0.74% and 2.27%. When evaluating the head and neck plan, DECT optimization with 2% range-uncertainty margins achieved a small reduction in organ-at-risk doses compared with that of SECT plans with 3.5% range-uncertainty margins. For the liver case, DECT was used to identify and correct the lipiodol SPR in the SECT plan.</p><p><strong>Conclusion: </strong>It is feasible to use DECT for proton-dose calculation in a commercial treatment planning system in a safe manner. The range margins can be reduced to 2% in some sites, including the head and neck.</p>","PeriodicalId":36923,"journal":{"name":"International Journal of Particle Therapy","volume":" ","pages":"62-72"},"PeriodicalIF":1.7,"publicationDate":"2021-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8270086/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39203655","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":"Facilitating MR-Guided Adaptive Proton Therapy in Children Using Deep Learning-Based Synthetic CT.","authors":"Chuang Wang,&nbsp;Jinsoo Uh,&nbsp;Thomas E Merchant,&nbsp;Chia-Ho Hua,&nbsp;Sahaja Acharya","doi":"10.14338/IJPT-20-00099.1","DOIUrl":"https://doi.org/10.14338/IJPT-20-00099.1","url":null,"abstract":"<p><strong>Purpose: </strong>To determine whether self-attention cycle-generative adversarial networks (cycle-GANs), a novel deep-learning method, can generate accurate synthetic computed tomography (sCT) to facilitate adaptive proton therapy in children with brain tumors.</p><p><strong>Materials and methods: </strong>Both CT and T1-weighted magnetic resonance imaging (MRI) of 125 children (ages 1-20 years) with brain tumors were included in the training dataset. A model introducing a self-attention mechanism into the conventional cycle-GAN was created to enhance tissue interfaces and reduce noise. The test dataset consisted of 7 patients (ages 2-14 years) who underwent adaptive planning because of changes in anatomy discovered on MRI during proton therapy. The MRI during proton therapy-based sCT was compared with replanning CT (ground truth).</p><p><strong>Results: </strong>The Hounsfield unit-mean absolute error was significantly reduced with self-attention cycle-GAN, as compared with conventional cycle-GAN (65.3 ± 13.9 versus 88.9 ± 19.3, <i>P</i> < .01). The average 3-dimensional gamma passing rates (2%/2 mm criteria) for the original plan on the anatomy of the day and for the adapted plan were high (97.6% ± 1.2% and 98.9 ± 0.9%, respectively) when using sCT generated by self-attention cycle-GAN. The mean absolute differences in clinical target volume (CTV) receiving 95% of the prescription dose and 80% distal falloff along the beam axis were 1.1% ± 0.8% and 1.1 ± 0.9 mm, respectively. Areas of greatest dose difference were distal to the CTV and corresponded to shifts in distal falloff. Plan adaptation was appropriately triggered in all test patients when using sCT.</p><p><strong>Conclusion: </strong>The novel cycle-GAN model with self-attention outperforms conventional cycle-GAN for children with brain tumors. Encouraging dosimetric results suggest that sCT generation can be used to identify patients who would benefit from adaptive replanning.</p>","PeriodicalId":36923,"journal":{"name":"International Journal of Particle Therapy","volume":"8 3","pages":"11-20"},"PeriodicalIF":1.7,"publicationDate":"2021-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8768893/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39592760","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}