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https://www.readbyqxmd.com/read/29786861/temporally-feathered-intensity-modulated-radiation-therapy-a-planning-technique-to-reduce-normal-tissue-toxicity
#1
Juan Carlos López Alfonso, Shireen Parsai, Nikhil Joshi, Andrew Godley, Chirag Shah, Shlomo A Koyfman, Jimmy J Caudell, Clifton D Fuller, Heiko Enderling, Jacob G Scott
PURPOSE: Intensity modulated radiation therapy (IMRT) has allowed optimization of three-dimensional spatial radiation dose distributions permitting target coverage while reducing normal tissue toxicity. However, radiation-induced normal tissue toxicity is a major contributor to patients' quality of life and often a dose-limiting factor in the definitive treatment of cancer with radiation therapy. We propose the next logical step in the evolution of IMRT using canonical radiobiological principles, optimizing the temporal dimension through which radiation therapy is delivered to further reduce radiation-induced toxicity by increased time for normal tissue recovery...
May 22, 2018: Medical Physics
https://www.readbyqxmd.com/read/29786614/a-novel-optimization-framework-for-vmat-with-dynamic-gantry-couch-rotation
#2
Qihui Lyu, Victoria Y Yu, Dan Ruan, Ryan Neph, Daniel O'Connor, Ke Sheng
Existing Volumetric Modulated Arc Therapy (VMAT) optimization using coplanar arcs is highly efficient but usually dosimetrically inferior to intensity modulated radiation therapy (IMRT) with optimized non-coplanar beams. To achieve both dosimetric quality and delivery efficiency, we proposed in this study, a novel integrated optimization method for non-coplanar VMAT (4πVMAT). 4πVMAT with Direct Aperture Optimization (DAO) was achieved by utilizing a least square dose fidelity objective, along with an anisotropic total variation term for regularizing the fluence smoothness, a single segment term for imposing simple apertures, and a group sparsity term for selecting beam angles...
May 22, 2018: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29786611/increased-accuracy-of-planning-tools-for-optimization-of-dynamic-multileaf-collimator-delivery-of-radiotherapy-through-reformulated-objective-functions
#3
Lovisa Engberg, Kjell Eriksson, Anders Forsgren
The purpose of this study is to examine in a clinical setting a novel formulation of objective functions for intensity-modulated radiotherapy (IMRT) treatment plan multicriteria optimization (MCO) that we suggested in a recent study. The proposed objective functions are extended with dynamic multileaf collimator (DMLC) delivery constraints from the literature, and a tailored interior point method is described to efficiently solve the resulting optimization formulation. In a numerical planning study involving three patient cases, DMLC plans Pareto optimal to the MCO formulation with the proposed objective functions are generated...
May 22, 2018: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29785725/density-scaling-of-phantom-materials-for-a-3d-dose-verification-system
#4
Kensuke Tani, Yukio Fujita, Akihisa Wakita, Ryohei Miyasaka, Ryuzo Uehara, Takumi Kodama, Yuya Suzuki, Ako Aikawa, Norifumi Mizuno, Jiro Kawamori, Hidetoshi Saitoh
In this study, the optimum density scaling factors of phantom materials for a commercially available three-dimensional (3D) dose verification system (Delta4) were investigated in order to improve the accuracy of the calculated dose distributions in the phantom materials. At field sizes of 10 × 10 and 5 × 5 cm2 with the same geometry, tissue-phantom ratios (TPRs) in water, polymethyl methacrylate (PMMA), and Plastic Water Diagnostic Therapy (PWDT) were measured, and TPRs in various density scaling factors of water were calculated by Monte Carlo simulation, Adaptive Convolve (AdC, Pinnacle3 ), Collapsed Cone Convolution (CCC, RayStation), and AcurosXB (AXB, Eclipse)...
May 21, 2018: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/29785183/evaluation-of-reirradiation-in-locally-advanced-head-and-neck-cancers-toxicity-and-early-clinical-outcomes
#5
Amit Bahl, Arun Singh Oinam, Arun Elangovan, Satinder Kaur, Gaurav Trivedi, Roshan Verma, Sudhir Bhandari, Sushmita Ghoshal, Naresh Kumar Panda
Objectives: Locoregional recurrence is the predominant pattern of treatment failure in advanced head and neck cancers. Reirradiation is a useful modality to treat inoperable head and neck cancer patients with recurrent disease. The aim of the present study was to analyze the treatment toxicity and early clinical outcomes in patients undergoing reirradiation. Methods: Twenty patients of head and neck cancers with recurrences or second cancers were evaluated. Reirradiation was done using simultaneous integrated boost volumetric modulated arc therapy (SIB VMAT), intensity modulated radiotherapy (IMRT), or conventional radiotherapy using 6MV photons...
2018: Journal of Oncology
https://www.readbyqxmd.com/read/29781165/dose-rate-response-of-digital-megavolt-imager-detector-for-flattening-filter-free-beams
#6
Zhigang Xu, Jinkoo Kim, James Han, An Ting Hsia, Samuel Ryu
In this study we investigated the dose rate response characteristics of the Digital Megavolt Imager (DMI) detector, including panel saturation, linearity, and imager ghosting effects for flattening filter-free (FFF) beams. The DMI detector dose rate response characteristics were measured as a function of dose rate on a Varian TrueBeam machine. Images were acquired at dose rates ranging from 400 to 1400 MU/min for 6XFFF and 400 to 2400 MU/min for 10XFFF. Line profiles and central portal doses derived from the images were analyzed and compared...
May 21, 2018: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/29778320/simultaneously-avoiding-the-hippocampus-and-hypothalamic-pituitary-axis-during-whole-brain-radiotherapy-a-planning-study
#7
Xing-Wen Fan, Juan-Qi Wang, Jun-Lan Wu, Hong-Bing Wang, Kai-Liang Wu
Whole brain radiotherapy (WBRT) is the preferred treatment for multiple brain metastases, and patients with limited-stage small cell lung cancer undergo prophylactic cranial irradiation after complete remission. However, neurotoxicity remains a complication. In addition to protecting the hippocampus from irradiation to preserve cognitive function, it is also critical to avoid irradiating the hypothalamic-pituitary axis to preserve endocrine and immune function. This study aimed to evaluate the feasibility of delivering WBRT while protecting the hippocampus and hypothalamic-pituitary axis...
May 16, 2018: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
https://www.readbyqxmd.com/read/29777595/a-ring-based-compensator-imrt-system-optimized-for-low-and-middle-income-countries-design-and-treatment-planning-study
#8
Jonathon Van Schelt, Daniel Smith, Nicholas Fong, Dolla Toomeh, Patricia A Sponseller, Derek W Brown, Meghan W Macomber, Nina A Mayr, Shilpen Patel, Adam Shulman, G V Subrahmanyam, K Govindarajan, Eric C Ford
PURPOSE: We propose a novel compensator-based IMRT system designed to provide a simple, reliable, and cost-effective adjunct technology, with the goal of expanding global access to advanced radiotherapy techniques. The system would employ easily-reusable tungsten bead compensators that operate independent of a gantry (e.g. mounted in a ring around the patient). Thereby the system can be retrofitted to existing linac and cobalt teletherapy units. This study explores the quality of treatment plans from the proposed system and the dependence on associated design parameters...
May 19, 2018: Medical Physics
https://www.readbyqxmd.com/read/29776418/the-impact-of-contour-variation-on-tumour-control-probability-in-anal-cancer
#9
Michael P Jones, Jarad Martin, Kerwyn Foo, Patrick Estoesta, Lois Holloway, Michael Jameson
BACKGROUND: While intensity modulated radiotherapy (IMRT) has been widely adopted for the treatment of anal cancer (AC), the added contour complexity poses potential risks. This study investigates the impact of contour variation on tumour control probability (TCP) when using IMRT for AC. METHODS: Nine Australian centres contoured a single computed tomography dataset of a patient with AC. The same optimised template-based IMRT planning protocol was applied to each contour set to generate nine representative treatment plans and their corresponding dose volume histograms...
May 18, 2018: Radiation Oncology
https://www.readbyqxmd.com/read/29774779/image-guided-radiation-therapy-for-post-operative-gynaecologic-cancer-patient-set-up-verification-with-and-without-implanted-fiducial-markers
#10
Donna H Murrell, Andrew Warner, Quinn Benwell, Wendy Wells, Danielle Scott, Vikram Velker, George Hajdok, David P D'Souza
BACKGROUND: Intensity modulated radiotherapy (IMRT) is increasingly being used to treat gynaecological malignancies in the postoperative setting. The purpose of this study was to evaluate the use of image-guided radiotherapy (IGRT) using cone-beam computed tomography (CBCT) with fiducial markers for daily localization. MATERIAL AND METHODS: A single institution study was performed of consecutive cervical or endometrial cancer patients receiving adjuvant external beam radiotherapy (n = 15)...
May 18, 2018: Acta Oncologica
https://www.readbyqxmd.com/read/29774396/tumor-volume-as-a-prognostic-marker-in-p16-positive-and-p16-negative-oropharyngeal-cancer-patients-treated-with-definitive-intensity-modulated-radiotherapy
#11
Timo Carpén, Kauko Saarilahti, Caj Haglund, Antti Markkola, Jussi Tarkkanen, Jaana Hagström, Petri Mattila, Antti Mäkitie
PURPOSE: To investigate the impact of primary gross tumor volume (pGTV) and nodal gross tumor volume (nGTV) in oropharyngeal squamous cell carcinoma (OPSCC) and the difference in their role between human papillomavirus (HPV)-positive and HPV-negative patients. METHODS: The patient cohort consists of 91 OPSCC patients treated with definitive radiochemotherapy or radiotherapy using intensity-modulated radiotherapy (IMRT). All patients had a minimum follow-up of 31 months...
May 17, 2018: Strahlentherapie und Onkologie: Organ der Deutschen Röntgengesellschaft ... [et Al]
https://www.readbyqxmd.com/read/29773442/treatment-related-toxicity-in-men-who-received-intensity-modulated-versus-3d-conformal-radiotherapy-after-radical-prostatectomy-a-national-population-based-study
#12
Arunan Sujenthiran, Julie Nossiter, Matthew Parry, Susan C Charman, Paul J Cathcart, Jan van der Meulen, Noel W Clarke, Heather Payne, Ajay Aggarwal
BACKGROUND AND PURPOSE: In the post-prostatectomy setting the value of Intensity-modulated (IMRT) relative to 3D-conformal radiotherapy (3D-CRT) in reducing toxicity remains unclear. We compared genitourinary (GU) and gastrointestinal (GI) toxicity after post-prostatectomy IMRT or 3D-CRT. MATERIALS AND METHODS: A population-based study of all patients treated with post-prostatectomy 3D-CRT (n = 2422) and IMRT (n = 603) was conducted between January 1 2010 and December 31 2013 in the English National Health Service...
May 14, 2018: Radiotherapy and Oncology: Journal of the European Society for Therapeutic Radiology and Oncology
https://www.readbyqxmd.com/read/29772065/isodose-feature-preserving-voxelization-ifpv-for-radiation-therapy-treatment-planning
#13
Hongcheng Liu, Lei Xing
PURPOSE: Inverse planning involves iterative optimization of a large number of parameters and is known to be a labor-intensive procedure. To reduce the scale of computation and improve characterization of isodose plan, this paper presents an isodose feature-preserving voxelization (IFPV) framework for radiation therapy applications and demonstrate an implementation of inverse planning in the IFPV domain. METHODS: A dose distribution in IFPV scheme is characterized by partitioning the voxels into subgroups according to their geometric and dosimetric values...
May 17, 2018: Medical Physics
https://www.readbyqxmd.com/read/29769143/clinical-outcome-of-elderly-patients-%C3%A2-70-years-with-esophageal-cancer-undergoing-definitive-or-neoadjuvant-radio-chemo-therapy-a-retrospective-single-center-analysis
#14
Franziska Walter, David Böckle, Nina-Sophie Schmidt-Hegemann, Rebecca Köpple, Sabine Gerum, Stefan Boeck, Martin Angele, Claus Belka, Falk Roeder
BACKGROUND: To analyse the outcome of elderly patients (≥70 years) with esophageal cancer treated with curative intent radio(chemo)therapy. METHODS: Fifty five patients (median 75 years) receiving curative intent radio(chemo)therapy for esophageal cancer from 1999 to 2015 were retrospectively analyzed. Most patients showed locally advanced disease (T3/4:78%, N+:58%) with squamous cell histology (74%). Charlson comorbidity score was > 1 in 27%. 48 patients (87%) received definitive treatment while 7 patients were treated neoadjuvantly...
May 16, 2018: Radiation Oncology
https://www.readbyqxmd.com/read/29769060/biopro-rcmi-1505-trial-multicenter-study-evaluating-the-use-of-a-biodegradable-balloon-for-the-treatment-of-intermediate-risk-prostate-cancer-by-intensity-modulated-radiotherapy-study-protocol
#15
David Pasquier, Emilie Bogart, François Bonodeau, Thomas Lacornerie, Eric Lartigau, Igor Latorzeff
BACKGROUND: Prospective trials have demonstrated the advantage of dose-escalated radiotherapy for the biochemical and clinical control of intermediate risk prostate cancer. Dose escalation improves outcomes but increases risks of urinary and bowel toxicity. Recently the contribution of "spacers" positioned in the septum between the rectum and the prostate could improve the functional results of intensity modulated radiation therapy (IMRT). To date most of the evaluated devices were polyethylen glycol (PEG) and hyaluronic acid (HA)...
May 16, 2018: BMC Cancer
https://www.readbyqxmd.com/read/29765265/is-volumetric-modulated-arc-therapy-with-constant-dose-rate-a-valid-option-in-radiation-therapy-for-head-and-neck-cancer-patients
#16
Annamaria Didona, Valentina Lancellotta, Claudio Zucchetti, Bianca Moira Panizza, Alessandro Frattegiani, Martina Iacco, Anna Concetta Di Pilato, Simonetta Saldi, Cynthia Aristei
Background: Intensity-modulated radiotherapy (IMRT) improves dose distribution in head and neck (HN) radiation therapy. Volumetric-modulated arc therapy (VMAT), a new form of IMRT, delivers radiation in single or multiple arcs, varying dose rates (VDR-VMAT) and gantry speeds, has gained considerable attention. Constant dose rate VMAT (CDR-VMAT) associated with a fixed gantry speed does not require a dedicated linear accelerator like VDR-VMAT. The present study explored the feasibility, efficiency and delivery accuracy of CDR-VMAT, by comparing it with IMRT and VDR-VMAT in treatment planning for HN cancer...
May 2018: Reports of Practical Oncology and Radiotherapy
https://www.readbyqxmd.com/read/29765233/patterns-of-local-failures-and-suggestions-for-reduction-of-clinical-target-volume-for-nasopharyngeal-carcinoma-patients-without-cervical-lymph-node-metastasis
#17
Yujiao Li, Xiaomin Ou, Chunying Shen, Tingting Xu, Weiwei Li, Chaosu Hu
Background: To demonstrate the robustness of clinical target volume delineation for nasopharyngeal carcinoma (NPC) patients, this study makes a detailed analysis of the initial irradiated dose of the recurrent site and local failure patterns after intensity-modulated radiation therapy (IMRT). Based on this analysis, further improvement of delineation recommendations may be made in order to improve the quality-of-life in NPC, without decreasing the local control and survival rate. Methods: In total, 382 newly diagnosed non-metastatic NPC patients were retrospectively enrolled, receiving elective neck irradiation to levels II, III, and VA...
2018: OncoTargets and Therapy
https://www.readbyqxmd.com/read/29764515/long-term-outcome-of-a-moderately-hypofractionated-intensity-modulated-radiotherapy-approach-using-an-endorectal-balloon-for-patients-with-localized-prostate-cancer
#18
Bin S Teh, Gary D Lewis, Weiyuan Mai, Ramiro Pino, Hiromichi Ishiyama, Edward Brian Butler
BACKGROUND: Technical advances in radiotherapy delivery have simultaneously enabled dose escalation and enhanced bladder and rectal sparing. However, the optimal radiation fractionation regimen for localized prostate cancer is unclear. Laboratory and clinical evidence suggest that hypofractionation may improve the therapeutic ratio of radiotherapy. We report our institutional outcomes using moderately hypofractionated, intensity-modulated radiotherapy (IMRT), and an endorectal balloon, with emphasis on long-term biochemical control and treatment-related adverse events in patients with localized prostate cancer...
April 17, 2018: Cancer communications
https://www.readbyqxmd.com/read/29764449/primo-software-as-a-tool-for-monte-carlo-simulations-of-intensity-modulated-radiotherapy-a-feasibility-study
#19
Alessandro Esposito, Sofia Silva, Jorge Oliveira, Joana Lencart, João Santos
BACKGROUND: IMRT provides higher dose conformation to the target and dose sparing to surrounding tissues than 3DCRT. Monte Carlo method in Medical Physics is not a novelty to approach dosimetric problems. A new PENELOPE based code named PRIMO recently was published. The most intriguing features of PRIMO are the user-friendly approach, the stand-alone property and the built-in definition of different linear accelerators models. Nevertheless, IMRT simulations are not yet implemented. METHODS: A Varian Trilogy with a Millennium120 MLC and a Varian Novalis with 120HD MLC were studied...
May 15, 2018: Radiation Oncology
https://www.readbyqxmd.com/read/29764185/management-of-metastatic-spinal-cord-compression-among-veterans-health-administration-radiation-oncologists
#20
Ruchika Gutt, Sheeta Malhotra, Shruti Jolly, Drew Moghanaki, Alice V Cheuk, Helen Fosmire, Maria Kelly, Lori Hoffman-Hogg, Stephen Lutz, Mitchell Anscher, George Dawson
BACKGROUND: Optimal management of metastatic spinal cord compression (MSCC) improves functional outcomes in patients with metastatic disease. This survey study evaluated management of MSCC by Veterans Health Administration (VHA) radiation oncologists (ROs), to determine whether management of MSCC correlates with American College of Radiology (ACR) guidelines, and to compare times to initiation of treatment between surgery and radiotherapy (RT). METHODS: Surveys emailed to 79 VHA ROs included questions on steroid use, surgical care, palliative care, fractionation of irradiation, re-irradiation, and management of common MSCC case scenarios...
April 2018: Annals of Palliative Medicine
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