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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
#1
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/29159915/performance-of-a-hybrid-monte-carlo-pencil-beam-dose-algorithm-for-proton-therapy-inverse-planning
#2
Ana María Barragán Montero, Kevin Souris, Daniel Sánchez Parcerisa, Edmond Sterpin, John Aldo Lee
PURPOSE: Analytical algorithms have a limited accuracy when modelling very heterogeneous tumor sites. This work addresses the performance of a hybrid dose optimizer that combines both Monte Carlo (MC) and pencil beam (PB) dose engines to get the best trade-off between speed and accuracy for proton therapy plans. METHODS: The hybrid algorithm calculates the optimal spot weights (w) by means of an iterative optimization process where the dose at each iteration is computed by using a precomputed dose influence matrix based on the conventional PB plus a correction term c obtained from a MC simulation...
November 21, 2017: Medical Physics
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
#3
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
#4
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/29152838/commissioning-of-the-world-s-first-compact-pencil-beam-scanning-proton-therapy-system
#5
Rajesh Pidikiti, Bijal C Patel, Matthew R Maynard, Joseph P Dugas, Joseph Syh, Narayan Sahoo, Hsinshun Terry Wu, Lane R Rosen
This paper summarizes clinical commissioning of the world's first commercial, clinically utilized installation of a compact, image-guided, pencil-beam scanning, intensity-modulated proton therapy system, the IBA Proteus(®) ONE, at the Willis-Knighton Cancer Center (WKCC) in Shreveport, LA. The Proteus(®) ONE is a single-room, compact-gantry system employing a cyclotron-generated proton beam with image guidance via cone-beam CT as well as stereoscopic orthogonal and oblique planar kV imaging. Coupling 220° of gantry rotation with a 6D robotic couch capable of in plane patient rotations of over 180° degrees allows for 360° of treatment access...
November 20, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/29152444/excellent-pathologic-response-and-atypical-clinical-course-of-high-grade-extremity-sarcoma-to-neoadjuvant-pencil-beam-scanning-proton-therapy
#6
Jill Remick, William Regine, Robert Malyapa, Vincent Ng, Melissa Vyfhuis, Tejan Diwanji, Susan Shyu, James W Snider
Neoadjuvant radiation therapy, followed by definitive surgical resection, remains the standard of care for resectable high-grade and unresectable soft tissue sarcomas. Proton therapy offers the promise of highly conformal dose distributions with improved sparing of neighboring normal tissues as compared with conformal and intensity modulated photon techniques. It is unclear whether proton therapy may offer an improved tumoral response, especially with dose escalation, in this relatively radio-insensitive tumor type...
September 15, 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
#7
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
#8
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
#9
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
#10
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
#11
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
#12
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/29148554/modelling-direct-dna-damage-for-gold-nanoparticle-enhanced-proton-therapy
#13
Marios Sotiropoulos, Nicholas T Henthorn, John W Warmenhoven, Ranald I Mackay, Karen J Kirkby, Michael J Merchant
Gold nanoparticles have been proven as potential radiosensitizer when combined with protons. Initially the radiosensitization effect was attributed to the physical interactions of radiation with the gold and the production of secondary electrons that induce DNA damage. However, emerging data challenge this hypothesis, supporting the existence of alternative or supplementary radiosensitization mechanisms. In this work we incorporate a realistic cell model with detailed DNA geometry and a realistic gold nanoparticle biodistribution based on experimental data...
November 17, 2017: Nanoscale
https://www.readbyqxmd.com/read/29134674/experimental-validation-of-two-dual-energy-ct-methods-for-proton-therapy-using-heterogeneous-tissue-samples
#14
Esther Bär, Arthur Lalonde, Rongxiao Zhang, Kyung-Wook Jee, Kai Yang, Gregory Sharp, Bob Liu, Gary Royle, Hugo Bouchard, Hsiao-Ming Lu
PURPOSE: The purpose of this work is to evaluate the performance of dual-energy CT (DECT) for determining proton stopping power ratios (SPRs) in an experimental environment and to demonstrate its potential advantages over conventional single-energy CT (SECT) in clinical conditions. METHODS: Water equivalent range (WER) measurements of 12 tissue-equivalent plastic materials and 12 fresh animal tissue samples are performed in a 195 MeV broad proton beam using the dose extinction method...
November 14, 2017: Medical Physics
https://www.readbyqxmd.com/read/29131808/linear-energy-transfer-incorporated-intensity-modulated-proton-therapy-optimization
#15
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/29128229/proton-beam-therapy-for-iris-melanomas-in-107-patients
#16
Juliette Thariat, Ahmed Rahmi, Julia Salleron, Carlo Mosci, Benjamin Butet, Celia Maschi, Francesco Lanza, Sara Lanteri, Stephanie Baillif, Joel Herault, Thibaud Mathis, Jean Pierre Caujolle
PURPOSE: To report on the clinical characteristics and outcomes for patients with iris melanoma using proton therapy. DESIGN: Retrospective study. PARTICIPANTS: One hundred seven patients with iris melanoma from 3 regional ophthalmologic centers. METHODS: A retrospective study was conducted for iris melanoma patients from 3 regional ophthalmologic centers referred to and treated at a single proton therapy facility between 1996 and 2015...
November 8, 2017: Ophthalmology
https://www.readbyqxmd.com/read/29118323/valproic-acid-sensitizes-hepatocellular-carcinoma-cells-to-proton-therapy-by-suppressing-nrf2-activation
#17
Jeong Il Yu, Changhoon Choi, Sung-Won Shin, Arang Son, Ga-Haeng Lee, Shin-Yeong Kim, Hee Chul Park
Although efficacy of combined histone deacetylase (HDAC) inhibitors and conventional photon radiotherapy is being tested in clinical trials, their combined effect with proton beam radiotherapy has yet to be determined. Here, we compared combined effect of valproic acid (VPA), a class I and II HDAC inhibitor and antiepileptic drug with proton and photon irradiation in hepatocellular carcinoma (HCC) cells in vitro and in vivo. We found that VPA sensitized more Hep3B cells to proton than to photon irradiation...
November 8, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29116399/intravitreal-bevacizumab-for-neovascular-glaucoma-in-uveal-melanoma-treated-by-proton-beam-therapy
#18
Amir Mahdjoubi, Marie Najean, Stéphanie Lemaitre, Sylvain Dureau, Rémi Dendale, Christine Levy, Livia Lumbroso-Le Rouic, Laurence Desjardins, Nathalie Cassoux
BACKGROUND: To evaluate the efficacy of bevacizumab on reduction of the enucleation rate and control of intraocular pressure (IOP) in neovascular glaucoma (NVG)-complicating proton beam therapy for UM and to identify the determinants of the efficacy of bevacizumab. METHODS: Retrospective comparative study of patients with rubeosis following proton therapy for uveal melanoma. Patients were divided into two groups: a bevacizumab group and a control group which comprised two subgroups: panretinal photocoagulation (PRP)/cryotherapy and observation subgroups...
November 7, 2017: Graefe's Archive for Clinical and Experimental Ophthalmology
https://www.readbyqxmd.com/read/29116055/improvement-of-single-detector-proton-radiography-by-incorporating-intensity-of-time-resolved-dose-rate-functions
#19
Rongxiao Zhang, Kyung-Wook Jee, Ethan W Cascio, Gregory C Sharp, Jacob B Flanz, Hsiao-Ming Lu
Proton radiography, which images patients with the same type of particles as what they are to be treated with, is a promising approach to image guidance and water equivalent path length (WEPL) verification in proton radiation therapy. We have shown recently that proton radiographs could be obtained by measuring time-resolved dose rate functions (DRF) using an x-ray amorphous silicon flat panel. The WEPL values were derived solely from the root-mean-square (RMS) of DRFs while the intensity information in the DRFs was filtered out...
November 8, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29115716/long-term-results-in-children-with-head-and-neck-rhabdomyosarcoma-a-report-from-the-italian-soft-tissue-sarcoma-committee
#20
Maria Carmen Affinita, Andrea Ferrari, Giuseppe Maria Milano, Giovanni Scarzello, Francesco De Leonardis, Luca Coccoli, Roberta Pericoli, Eleonora Basso, Ilaria Zanetti, Angela Scagnellato, Gianni Bisogno
BACKGROUND: Rhabdomyosarcoma (RMS) occurring at nonparameningeal head and neck (NPM-HN) sites carries a better prognosis than parameningeal RMS and some other sites. We analyzed the treatments administered and results obtained in patients with localized NPM-HN RMS, included in the protocols coordinated by the Italian Soft Tissue Sarcoma Committee (STSC), in an effort to identify prognostic factors that could facilitate the tailoring of treatment. METHODS: Sixty-six patients up to 18 years of age with previously untreated, localized NPM-HN RMS were prospectively registered in three consecutive protocols: RMS79, RMS88, and RMS96...
November 8, 2017: Pediatric Blood & Cancer
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