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https://www.readbyqxmd.com/read/29219119/density-overwrites-of-internal-tumor-volumes-in-intensity-modulated-proton-therapy-plans-for-mobile-lung-tumors
#1
Pablo Botas, Clemens Grassberger, Gregory Sharp, Harald Paganetti
The purpose of this study was to investigate Internal Tumor Volume (ITV) density overwrite strategies to minimize Intensity Modulated Proton Therapy (IMPT) plan degradation of mobile lung tumors. Four planning paradigms were compared for nine lung cancer patients. IGTV and ICTV structures were defined encompassing their respective volumes in every 4DCT phase. The paradigms use different planning CT (pCT) created from the Average Intensity Projection (AIP) of the 4DCT, overwriting the density within the IGTV to account for movement...
December 8, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29188150/a-rare-case-of-unresectable-adenoid-cystic-carcinoma-of-the-nasopharynx-treated-with-intensity-modulated-proton-therapy
#2
Jae Phan, Sweet Ping Ng, Courtney Pollard Iii, Jack Phan
Adenoid cystic carcinoma (ACC) is generally treated with surgical resection followed by postoperative radiotherapy. In cases where surgical management is precluded due to the location of the tumor and/or patient factors, radiation therapy can be offered to achieve local control. Here, we present a case of unresectable Stage T4N0 ACC of the nasopharynx with skull base and intracranial extension treated with intensity modulated proton therapy (IMPT), which achieved good local control with no significant late toxicity...
September 15, 2017: Curēus
https://www.readbyqxmd.com/read/29178546/evaluation-of-dosimetric-advantages-of-using-patient-specific-aperture-system-with-intensity-modulated-proton-therapy-for-the-shallow-depth-tumor
#3
Keisuke Yasui, Toshiyuki Toshito, Chihiro Omachi, Kensuke Hayashi, Kenichiro Tanaka, Kumiko Asai, Akira Shimomura, Rie Muramatsu, Naoki Hayashi
In this study, we evaluate dosimetric advantages of using patient-specific aperture system with intensity-modulated proton therapy (IMPT) for head and neck tumors at the shallow depth. We used four types of patient-specific aperture system (PSAS) to irradiate shallow regions less than 4 g/cm2 with a sharp lateral penumbra. Ten head and neck IMPT plans with or without aperture were optimized separately with the same 95% prescription dose and same dose constraint for organs at risk (OARs). The plans were compared using dose volume histograms (DVHs), dose distributions, and some dose indexes such as volume receiving 50% of the prescribed dose (V50 ), mean or maximum dose (Dmean and Dmax ) to the OARs...
November 27, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/29165322/treatment-planning-with-intensity-modulated-particle-therapy-for-multiple-targets-in-stage-iv-non-small-cell-lung-cancer
#4
Kristjan Anderle, Joep Stroom, Sandra Vieira, Nuno Pimentel, Carlo Greco, Marco Durante, Christian Graeff
Intensity modulated particle therapy (IMPT) can produce highly conformal plans, but is limited in advanced lung cancer patients with multiple lesions due to motion and planning complexity. A 4D IMPT optimization including all motion states was expanded to include multiple targets, where each target (isocenter) is designated to specific field(s). Furthermore, to achieve stereotactic treatment planning objectives, target and OAR weights plus objective doses were automatically iteratively adapted. Finally, 4D doses were calculated for different motion scenarios...
November 22, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29160775/anatomical-robust-optimization-to-account-for-nasal-cavity-filling-variation-during-intensity-modulated-proton-therapy-a-comparison-with-conventional-and-adaptive-planning-strategies
#5
Steven van de Water, Francesca Albertini, Damien Charles Weber, Ben J M Heijmen, Mischa S Hoogeman, Antony John Lomax
The aim of this study is to develop an anatomical robust optimization method for intensity-modulated proton therapy (IMPT) that accounts for interfraction variations in nasal cavity filling, and to compare it with conventional single-field uniform dose (SFUD) optimization and online plan adaptation. We included CT data of five patients with tumors in the sinonasal region. Using the planning CT, we generated for each patient 25 'synthetic' CTs with varying nasal cavity filling. The robust optimization method available in our treatment planning system 'Erasmus-iCycle' was extended to also account for anatomical uncertainties by including (synthetic) CTs with varying patient anatomy as error scenarios in the inverse optimization...
November 21, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29159011/proton-therapy-for-malignant-pleural-mesothelioma-a-three-case-series-describing-the-clinical-and-dosimetric-advantages-of-proton-based-therapy
#6
Howard Lee, Jing Zeng, Stephen R Bowen, Ramesh Rengan
Malignant pleural mesothelioma (MPM) is a malignancy of the pleural cavity that typically presents at an advanced stage. Due to its large, circumferential clinical target volume (CTV) and proximity to major structures, including the heart and contralateral lung, delivering hemithoracic intensity-modulated radiotherapy (IMRT) with photon therapy to achieve loco-regional control following macroscopic complete resection is challenging. Intensity-modulated proton therapy (IMPT) has been shown to be a method for achieving higher therapeutic doses while limiting exposure to organs at risk (OARs), but patient outcomes after treatment have yet to be reported...
September 20, 2017: Curēus
https://www.readbyqxmd.com/read/29159005/field-specific-intensity-modulated-proton-therapy-optimization-technique-for-breast-cancer-patients-with-tissue-expanders-containing-metal-ports
#7
Maura Kirk, Gary Freedman, Thorsten Ostrander, Lei Dong
This report aims to propose and present an evaluation of a robust pencil beam scanning proton multi-field optimized treatment planning technique for postmastectomy radiation of breast cancer patients with implanted tissue expanders containing an internal metal port. Field-specific split targets were created for optimization to prevent spots from traveling through the metal port, while providing uniform coverage of the target with the use of a multi-field intensity modulated optimization approach. Two beam angles were strategically selected to provide complementary target coverage and plan robustness...
September 18, 2017: Curēus
https://www.readbyqxmd.com/read/29152442/combination-intensity-modulated-proton-therapy-and-passive-scatter-boost-for-rapidly-progressing-nasal-cavity-squamous-cell-carcinoma
#8
Sweet Ping Ng, Ethan B Ludmir, Manuel A Oyervides, Richard Y Wu, Steve Frank, G Brandon Gunn
Cancers of the nasal cavity and septum are associated with poor prognosis and are usually treated with surgery followed by post-operative radiotherapy with or without concurrent chemotherapy. Definitive radiotherapy is used in cases where the tumor is unresectable, patient is unfit for surgery, and/or the patient declines surgical intervention. Here, we present a case of a patient, who for non-medical reasons, opted to have non-surgical management of his rapidly progressing nasal cavity tumor. He was successfully treated with concurrent chemoradiotherapy utilizing a combination of intensity modulated proton therapy (IMPT) with passive scatter boost to reduce dose to the adjacent critical neural structures...
September 14, 2017: Curēus
https://www.readbyqxmd.com/read/29152431/intensity-modulated-proton-therapy-with-advanced-planning-techniques-in-a-challenging-hepatocellular-carcinoma-patient
#9
Smith Apisarnthanarax, Jatinder Saini, Avril O'Ryan-Blair, Jackie Castro, Stephen R Bowen
The use of radiation therapy has been increasing over recent years for the treatment of hepatocellular carcinoma (HCC). Proton beam therapy (PBT) has emerged as a promising treatment option for HCC patients due to its dosimetric advantages of sparing more normal liver tissue from radiation at low to moderate doses compared to photon-based treatments while still delivering high doses of radiation to tumors. The PBT therapy may be particularly beneficial in high-risk HCC cirrhotic patients with large, bulky tumors and/or vascular invasion complicated by surrounding perfusion abnormalities...
September 10, 2017: Curēus
https://www.readbyqxmd.com/read/29152430/a-dosimetric-comparison-of-intensity-modulated-proton-therapy-volumetric-modulated-arc-therapy-and-4%C3%AF-non-coplanar-intensity-modulated-radiation-therapy-for-a-patient-with-parameningeal-rhabdomyosarcoma
#10
Tiffany W Chen, Julian Sison, Becky Lee, Arthur J Olch, Andrew Chang, Annelise Giebeler, Kenneth Wong
Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in children and manifests as two major histological subtypes: embryonal and alveolar. The five-year local failure rate for RMS at parameningeal sites (middle ear, mastoid region, nasal cavity, etc.) is around 17% despite multiple Intergroup Rhabdomyosarcoma Study Group (IRS) trials conducted to determine the optimal radiation treatment regimen. This case report explores the use of intensity-modulated proton therapy (IMPT) for a 10-year-old child who presented with left eye irritation, facial pain, and headaches and was found to have an alveolar parameningeal rhabdomyosarcoma...
September 10, 2017: Curēus
https://www.readbyqxmd.com/read/29152427/dramatic-response-of-a-large-sacral-chordoma-to-intensity-modulated-proton-beam-therapy
#11
Craig Schneider, Melissa Vyfhuis, Emily Morse, Tejan Diwanji, James W Snider, Sina Mossahebi, Katarina Steacy, Robert Malyapa
Sacral chordomas are slow-growing, indolent, and locally invasive tumors that typically present with pain and neurologic dysfunction. Wide en-bloc surgical excision is the primary treatment, but achieving adequate margins is difficult and surgery is often associated with significant morbidity. Adjuvant radiation therapy (RT) is utilized to decrease the risk of local recurrence or as definitive treatment for nonsurgical candidates. Although chordomas are considered to be relatively radioresistant tumors, several studies have demonstrated tumor response to high-dose proton therapy...
September 10, 2017: Curēus
https://www.readbyqxmd.com/read/29148575/effects-of-spot-parameters-in-pencil-beam-scanning-treatment-planning
#12
Aafke Christine Kraan, Nicolas Depauw, Ben Clasie, Marina Giunta, Tom Madden, Hanne M Kooy
BACKGROUND: Spot size σ (in-air at isocenter), inter-spot spacing d, and spot charge q influence dose delivery efficiency and plan quality in Intensity Modulated Proton Therapy (IMPT) treatment planning. The choice and range of parameters varies among different manufacturers. The goal of this work is to demonstrate the influence of the spot parameters on dose quality and delivery in IMPT treatment plans, to show their interdependence, and to make practitioners aware of the spot parameter values for a certain facility...
November 17, 2017: Medical Physics
https://www.readbyqxmd.com/read/29148570/robust-optimization-in-impt-using-quadratic-objective-functions-to-account-for-the-minimum-mu-constraint
#13
Jie Shan, Yu An, Martin Bues, Steven E Schild, Wei Liu
PURPOSE: Currently, in clinical practice of intensity-modulated proton therapy (IMPT), the influence of the minimum monitor unit (MU) constraint is taken into account through post-processing after the optimization is completed. This may degrade the plan quality and plan robustness. This study aims to mitigate the impact of the minimum MU constraint directly during the plan robust optimization. METHODS AND MATERIALS: Cao et al. have demonstrated a two-stage method to account for the minimum MU constraint using linear programming without the impact of uncertainties considered...
November 17, 2017: Medical Physics
https://www.readbyqxmd.com/read/29131808/linear-energy-transfer-incorporated-intensity-modulated-proton-therapy-optimization
#14
Wenhua Cao, Azin Khabazian, Pablo P Yepes, Gino J Lim, Falk Poenisch, David R Grosshans, Radhe Mohan
The purpose of this study was to investigate the feasibility of incorporating linear energy transfer (LET) into the optimization of intensity modulated proton therapy (IMPT) plans. Because increased LET correlates with increased biological effectiveness of protons, high LETs in target volumes and low LETs in critical structures and normal tissues are preferred in an IMPT plan. However, if not explicitly incorporated into the optimization criteria, different IMPT plans may yield similar physical dose distributions but greatly different LET, specifically dose-averaged LET, distributions...
November 13, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29114596/clinical-outcomes-of-intensity-modulated-proton-therapy-and-concurrent-chemotherapy-in-esophageal-carcinoma-a-single-institutional-experience
#15
Anussara Prayongrat, Cai Xu, Heng Li, Steven H Lin
Purpose: Intensity-modulated proton therapy (IMPT) is an emerging advanced radiation technique. Although dosimetric studies demonstrate the superiority of IMPT for improving target conformity and reducing unnecessary dose to critical normal tissues, clinical experience is limited. We aim to describe our preliminary experience implementing IMPT concurrently with chemotherapy in esophageal carcinoma (EC). Methods and materials: From May 2011 through February 2016, 19 patients with EC (median age, 73 years) were treated with IMPT using 180 to 250 MV protons with a median dose of 50...
July 2017: Advances in Radiation Oncology
https://www.readbyqxmd.com/read/29101415/target-tailoring-and-proton-beam-therapy-to-reduce-small-bowel-dose-in-cervical-cancer-radiotherapy-a-comparison-of-benefits
#16
Peter de Boer, Agustinus J A J van de Schoot, Henrike Westerveld, Mark Smit, Marrije R Buist, Arjan Bel, Coen R N Rasch, Lukas J A Stalpers
PURPOSE: The aim of the study was to investigate the potential clinical benefit from both target tailoring by excluding the tumour-free proximal part of the uterus during image-guided adaptive radiotherapy (IGART) and improved dose conformity based on intensity-modulated proton therapy (IMPT). METHODS: The study included planning CTs from 11 previously treated patients with cervical cancer with a >4-cm tumour-free part of the proximal uterus on diagnostic magnetic resonance imaging (MRI)...
November 3, 2017: Strahlentherapie und Onkologie: Organ der Deutschen Röntgengesellschaft ... [et Al]
https://www.readbyqxmd.com/read/29076458/feasibility-of-mr-only-proton-dose-calculations-for-prostate-cancer-radiotherapy-using-a-commercial-pseudo-ct-generation-method
#17
Matteo Maspero, Cornelis A T Van den Berg, Guillaume Landry, Claus Belka, Katia Parodi, Peter R Seevinck, Bas W Raaymakers, Christopher Kurz
A magnetic resonance (MR)-only radiotherapy workflow can reduce cost, radiation exposure and uncertainties introduced by CT-MRI registration. A crucial prerequisite is generating the so called pseudo-CT (pCT) images for accurate dose calculation and planning. Many pCT generation methods have been proposed in the scope of photon radiotherapy. This work aims at verifying for the first time whether a commercially available photon-oriented pCT generation method can be employed for accurate intensity-modulated proton therapy (IMPT) dose calculation...
October 27, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29074078/the-impact-of-treatment-accuracy-on-proton-therapy-patient-selection-for-oropharyngeal-cancer-patients
#18
Tine Arts, Sebastiaan Breedveld, Martin A de Jong, Eleftheria Astreinidou, Lisa Tans, Fatma Keskin-Cambay, Augustinus D G Krol, Steven van de Water, Rik G Bijman, Mischa S Hoogeman
BACKGROUND AND PURPOSE: The impact of treatment accuracy on NTCP-based patient selection for proton therapy is currently unknown. This study investigates this impact for oropharyngeal cancer patients. MATERIALS AND METHODS: Data of 78 patients was used to automatically generate treatment plans for a simultaneously integrated boost prescribing 70 GyRBE/54.25 GyRBE in 35 fractions. IMRT treatment plans were generated with three different margins; intensity modulated proton therapy (IMPT) plans for five different setup and range robustness settings...
October 23, 2017: Radiotherapy and Oncology: Journal of the European Society for Therapeutic Radiology and Oncology
https://www.readbyqxmd.com/read/29054379/treatment-log-files-as-a-tool-to-identify-treatment-plan-sensitivity-to-inaccuracies-in-scanned-proton-beam-delivery
#19
Maria Francesca Belosi, Robert van der Meer, Paz Garcia de Acilu Laa, Alessandra Bolsi, Damien C Weber, Antony J Lomax
Dose distributions delivered at Gantry 2 at the Paul Scherrer Institut (PSI) can be reconstructed on the patient anatomy based on machine log files. With the present work, the dependency of the log file calculation on the planning optimization technique and on other planning parameters, such as field direction and tumour size, has been investigated. Interestingly, and despite the typically higher modulation of Intensity Modulated Proton Therapy (IMPT) plans, the results for both Single Field Uniform Distribution and IMPT approaches have been found to be similar...
October 17, 2017: Radiotherapy and Oncology: Journal of the European Society for Therapeutic Radiology and Oncology
https://www.readbyqxmd.com/read/29054378/multiple-ct-optimization-of-intensity-modulated-proton-therapy-is-it-possible-to-eliminate-adaptive-planning
#20
Xianliang Wang, Heng Li, Xiaorong Ronald Zhu, Qing Hou, Li Liao, Bo Jiang, Yupeng Li, Pei Wang, Jinyi Lang, Xiaodong Zhang
BACKGROUND AND PURPOSE: We hypothesized that a plan's robustness to anatomical changes can be improved by optimizing with multiple CT scans of a patient. The purpose of this study was to determine whether an intensity modulated proton therapy (IMPT) plan could be developed to meet dose criteria on both planning and adaptive CT plans. MATERIAL AND METHODS: Eight lung cancer patients who underwent adaptive IMPT were retrospectively selected. Each patient had two CTs: a primary planning CT (PCT) and an adaptive planning CT (ACT), and IMPT plans associated with the scans...
October 17, 2017: Radiotherapy and Oncology: Journal of the European Society for Therapeutic Radiology and Oncology
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