1,976 results match your criteria risk oar


Dosimetric comparison of VitalBeam and Halcyon 2.0 for hypofractionated VMAT with simultaneous integrated boost treatment of early-stage left-sided breast cancer.

J Appl Clin Med Phys 2021 Sep 23. Epub 2021 Sep 23.

Department of Radiation Oncology, College of Medicine, Korea University, Seoul, Korea.

Purpose: This study compared the quality of treatment plans for early-stage, left-sided breast cancer, as planned for and delivered by the Halcyon and VitalBeam .

Materials And Methods: Fifteen patients diagnosed with early-stage left-sided breast cancer, who had received VMAT with hypofractionated SIB, were recruited. All cases were planned using Halcyon comprising a dual-layer MLC (DL-MLC) and VitalBeam with a Millennium 120 MLC (VB-MLC). Read More

View Article and Full-Text PDF
September 2021

Assessment of HDR brachytherapy-replicating prostate radiotherapy planning for tomotherapy, cyberknife and VMAT.

Med Dosim 2021 Sep 19. Epub 2021 Sep 19.

Sir Charles Gairdner Hospital, Perth, Australia; 5D Clinics, Perth, Australia; University of Western Australia, Perth, Australia. Electronic address:

A dosimetric study was undertaken to assess the ability of Cyberknife (CK), Volumetric Modulated Arc Therapy (VMAT), and TomoTherapy (Tomo) to generate treatment plans that mimic the dosimetry of high dose-rate brachytherapy (HDR BT) for prostate cancer. The project aimed to assess the potential of using stereotactic body radiotherapy (SBRT) for boost treatment of high-risk prostate cancer patients where HDR BT in combination with conformal external beam radiotherapy (EBRT) is the standard of care. The datasets of 6 prostate patients previously treated with HDR BT were collated. Read More

View Article and Full-Text PDF
September 2021

Clinical impact of anisotropic analytical algorithm and Acuros XB dose calculation algorithms for intensity modulated radiation therapy in lung cancer patients.

J Xray Sci Technol 2021 Sep 15. Epub 2021 Sep 15.

Biophysics Department, Faculty of Science, Cairo University, Giza, Egypt.

Objective: To evaluate dose differences predicted between using Anisotropic Analytical Algorithm (AAA) and Acuros XB (AXB) in patients diagnosed with locally advanced non-small cell lung cancer (NSCLC) treated with intensity modulated radiation therapy (IMRT).

Methods: A phantom study was done to evaluate the dose prediction accuracy of AXB and AAA beyond low-density medium by comparing the calculated measurement results. Thirty-two advanced NSCLC patients were subjected to IMRT. Read More

View Article and Full-Text PDF
September 2021

Reliability of Hospital-Level Mortality in Abdominal Aortic Aneurysm Repair.

J Vasc Surg 2021 Sep 15. Epub 2021 Sep 15.

Center for Healthcare Outcomes and Policy, University of Michigan, Ann Arbor, MI; Department of Surgery, Section of Vascular Surgery, University of Michigan, Ann Arbor, MI.

Objective: The relationship between volume and surgical outcome has been shown for a variety of surgical procedures. The effect in abdominal aortic aneurysm repair continues to be debated. Reliability adjustment has been used as a method to remove statistical noise from hospital level outcomes but its impact on aortic aneurysm repair is not well understood. Read More

View Article and Full-Text PDF
September 2021

Can the mean linear energy transfer of organs be directly related to patient toxicities for current head and neck cancer intensity-modulated proton therapy practice?

Radiother Oncol 2021 Sep 14. Epub 2021 Sep 14.

Department of Radiation Oncology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands.

Background And Purpose: The relative biological effectiveness (RBE) of proton therapy is predicted to vary with the dose-weighted average linear energy transfer (LET). However, RBE values may substantially vary for different clinical endpoints. Therefore, the aim of this study was to assess the feasibility of relating mean D⋅LET parameters to patient toxicity for HNC patients treated with proton therapy. Read More

View Article and Full-Text PDF
September 2021

Use of magnetic resonance image-guided radiotherapy for breast cancer: a scoping review.

J Med Radiat Sci 2021 Sep 15. Epub 2021 Sep 15.

Olivia Newton John Cancer Wellness and Research Centre (ONCWRC), Austin Health, Heidelberg, Victoria, Australia.

In recent years, we have seen the integration of magnetic resonance imaging (MRI) simulators into radiotherapy centres and the emergence MR linear accelerators (MR-linac). Currently, there are limited studies to demonstrate the clinical effectiveness of MRI guided radiotherapy (MRIgRT) treatment for breast cancer patients. The objective of this scoping review was to identify and map the existing evidence surrounding the clinical implementation of MRIgRT for breast cancer patients. Read More

View Article and Full-Text PDF
September 2021

Fully automated noncoplanar radiation therapy treatment planning.

Med Phys 2021 Sep 14. Epub 2021 Sep 14.

Department of Radiation Oncology, Stanford University, Stanford, USA.

Purpose: To perform fully automated noncoplanar treatment planning, we propose a method called NC-POPS to produce noncoplanar (NC) plans using the Pareto Optimal Projection Search (POPS) algorithm.

Methods: Noncoplanar radiation therapy treatment planning has the potential to improve dosimetric quality as compared to traditional coplanar techniques. Likewise, automated treatment planning algorithms can reduce a planner's active treatment planning time and remove inter-planner variability. Read More

View Article and Full-Text PDF
September 2021

Predicting personalised optimal arc parameter using knowledge-based planning model for inoperable locally advanced lung cancer patients to reduce organ at risk doses.

Biomed Phys Eng Express 2021 Sep 22;7(6). Epub 2021 Sep 22.

Radiotherapy Physics, Queen's Centre for Oncology, Hull University Teaching Hospitals NHS Trust, Cottingham, HU16 5JQ, United Kingdom.

. Volumetric modulated arc therapy (VMAT) allows for reduction of organs at risk (OAR) volumes receiving higher doses, but increases OAR volumes receiving lower radiation doses and can subsequently increasing associated toxicity. Therefore, reduction of this low-dose-bath is crucial. Read More

View Article and Full-Text PDF
September 2021

Automatic radiotherapy delineation quality assurance on prostate MRI with deep learning in a multicentre clinical trial.

Phys Med Biol 2021 Sep 10. Epub 2021 Sep 10.

Institute of Medical Physics, University of Sydney School of Physics, Sydney, New South Wales, AUSTRALIA.

Volume delineation quality assurance (QA) is particularly important in clinical trial settings where consistent protocol implementation is required, as outcomes will affect future as well current patients. Currently, where feasible, this is conducted manually, which is time consuming and resource intensive. Although previous studies mostly focused on automating delineation QA on CT, magnetic resonance imaging (MRI) is being increasingly used in radiotherapy treatment. Read More

View Article and Full-Text PDF
September 2021

Multi-criteria optimization for planning volumetric-modulated arc therapy for prostate cancer.

PLoS One 2021 10;16(9):e0257216. Epub 2021 Sep 10.

Department of Radiation Oncology, Yeungnam University College of Medicine, Daegu, Republic of Korea.

We aimed to compare the volumetric-modulated arc therapy (VMAT) plans with or without multi-criteria optimization (MCO) on commercial treatment-planning systems (Eclipse, Varian Medical System, Palo Alto, CA, USA) for patients with prostate cancer. We selected 25 plans of patients with prostate cancer who were previously treated on the basis of a VMAT plan. All plans were imported into the Eclipse Treatment Planning System version 15. Read More

View Article and Full-Text PDF
September 2021

Providers PrEP: Identifying Primary Health care Providers' Biases as Barriers to Provision of Equitable PrEP Services.

J Acquir Immune Defic Syndr 2021 Oct;88(2):165-172

Center for AIDS Prevention Studies, Prevention Research Center, Division of Prevention Science, University of California, California, San Francisco.

Background: Despite their disparately high HIV incidence and voiced willingness to use pre-exposure prophylaxis (PrEP), Black cisgender women's knowledge and uptake of PrEP are low, especially relative to White cisgender women and men who have sex with men. Mounting evidence demonstrates that health care provider recommendations are a critical factor in women's awareness, willingness, and ability to uptake PrEP. Health care providers may make clinical judgments about who is (not) a good candidate for PrEP based on unconscious and conscious stereotypes and prejudice. Read More

View Article and Full-Text PDF
October 2021

Evaluation of auto-segmentation accuracy of cloud-based artificial intelligence and atlas-based models.

Radiat Oncol 2021 Sep 9;16(1):175. Epub 2021 Sep 9.

Department of Radiation Oncology, National Cancer Center Hospital, 5-1-1 Tsukiji, Chuo-ku, Tokyo, 104-0045, Japan.

Background: Contour delineation, a crucial process in radiation oncology, is time-consuming and inaccurate due to inter-observer variation has been a critical issue in this process. An atlas-based automatic segmentation was developed to improve the delineation efficiency and reduce inter-observer variation. Additionally, automated segmentation using artificial intelligence (AI) has recently become available. Read More

View Article and Full-Text PDF
September 2021

Recurrent infection is more common after endovascular versus open repair of infected abdominal aortic aneurysm: Systematic review and meta-analysis.

J Vasc Surg 2021 Sep 6. Epub 2021 Sep 6.

Department of Surgery, School of Medicine, University of Virginia, Charlottesville, VA; Division of Vascular and Endovascular Surgery, University of Virginia, Charlottesville, VA.

Objective: There remains a controversy regarding the use of endovascular aneurysm repair (EVAR) versus open aneurysm repair (OAR) for infected abdominal aortic aneurysms (AAA). This study aimed to investigate the comparative outcomes of EVAR and OAR for the treatment of infected AAAs.

Methods: We conducted a systematic review and meta-analysis using MEDLINE and EMBASE databases through May 2021. Read More

View Article and Full-Text PDF
September 2021

Radiation therapy for prostate cancer: What's the best in 2021.

Urologia 2021 Sep 8:3915603211042335. Epub 2021 Sep 8.

UOC di Radioterapia Oncologica, Dipartimento di Diagnostica per Immagini, Radioterapia Oncologica ed Ematologia, Fondazione Policlinico Universitario "A. Gemelli" IRCCS, Rome, Italy.

Radiotherapy is highly involved in the management of prostate cancer. Its features and potential applications experienced a radical evolution over last decades, as they are associated to the continuous evolution of available technology and current oncological innovations. Some application of radiotherapy like brachytherapy have been recently enriched by innovative features and multidisciplinary dedications. Read More

View Article and Full-Text PDF
September 2021

Effective Organs-at-Risk Dose Sparing in Volumetric Modulated Arc Therapy Using a Half-Beam Technique in Whole Pelvic Irradiation.

Front Oncol 2021 18;11:611469. Epub 2021 Aug 18.

Department of Radiation Oncology, Ajou University School of Medicine, Suwon, South Korea.

Background: Although there are some controversies regarding whole pelvic radiation therapy (WPRT) due to its gastrointestinal and hematologic toxicities, it is considered for patients with gynecological, rectal, and prostate cancer. To effectively spare organs-at-risk (OAR) doses using multi-leaf collimator (MLC)'s optimal segments, potential dosimetric benefits in volumetric modulated arc therapy (VMAT) using a half-beam technique (HF) were investigated for WPRT.

Methods: While the size of a fully opened field (FF) was decided to entirely include a planning target volume in all beam's eye view across arc angles, the HF was designed to use half the FF from the isocenter for dose optimization. Read More

View Article and Full-Text PDF

Automated clinical target volume delineation using deep 3D neural networks in radiation therapy of Non-small Cell Lung Cancer.

Phys Imaging Radiat Oncol 2021 Jul 23;19:131-137. Epub 2021 Aug 23.

Division of Radiation Biophysics, Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States.

Background And Purpose: Clinical targeted volume (CTV) delineation accounting for the patient-specific microscopic tumor spread can be a difficult step in defining the treatment volume. We developed an intelligent and automated CTV delineation system for locally advanced non-small cell lung carcinoma (NSCLC) to cover the microscopic tumor spread while avoiding organs-at-risk (OAR).

Materials And Methods: A 3D UNet with a customized loss function was used, which takes both the patients' respiration-correlated ("4D") CT scan and the physician contoured internal gross target volume (iGTV) as inputs, and outputs the CTV delineation. Read More

View Article and Full-Text PDF

Phase I Trial of Stereotactic MRI-guided Online Adaptive Radiation Therapy (SMART) for the Treatment of Oligometastatic Ovarian Cancer.

Int J Radiat Oncol Biol Phys 2021 Aug 30. Epub 2021 Aug 30.

Department of Radiation Oncology, Rutgers University, New Brunswick, NJ.

Objective: SBRT is increasingly used to treat a variety of oligometastatic histologies, but few data exist for ovarian cancer. Ablative SBRT dosing is challenging in sites like the abdomen, pelvis, and central thorax due to proximity and motion of organs-at-risk. A novel radiation delivery method, stereotactic magnetic-resonance-guided online-adaptive radiotherapy (SMART), may improve SBRT's therapeutic index through enhanced soft-tissue visualization, real-time non-ionizing imaging, and ability to adapt to the anatomy-of-the-day, with the goal of producing systemic-therapy-free intervals. Read More

View Article and Full-Text PDF

Dosimetric comparison of intensity modulated radiotherapy and intensity modulated proton therapy in the treatment of recurrent nasopharyngeal carcinoma.

Med Dosim 2021 Aug 29. Epub 2021 Aug 29.

Department of Medical Physics, Pamela Youde Nethersole Eastern Hospital, Hong Kong.

Background And Purpose: To compare the dosimetric performance of Intensity Modulated Proton Therapy (IMPT) and Intensity Modulated Radiotherapy (IMRT) in terms of target volume coverage and sparing of neurological organs-at-risk (OARs) in salvaging recurrent nasopharyngeal carcinoma (rNPC). The maximum dose to the internal carotid artery (ICA) and nasopharyngeal (NP) mucosa, which are associated with potential carotid blowout and massive epistaxis, were also evaluated.

Materials And Methods: IMRT and IMPT treatment plans were created for twenty patients with locally advanced rNPC. Read More

View Article and Full-Text PDF

Stereotactic body radiotherapy of lymph node metastases under MR-guidance: First clinical results and patient-reported outcomes.

Strahlenther Onkol 2021 Sep 1. Epub 2021 Sep 1.

Department of Radiation Oncology, Heidelberg University Hospital, Heidelberg, Germany.

Objective: Stereotactic body radiotherapy (SBRT) is a noninvasive treatment option for lymph node metastases (LNM). Magnetic resonance (MR)-guidance offers superior tissue contrast and enables treatment of targets in close vicinity to radiosensitive organs at risk (OAR). However, literature on MR-guided SBRT of LNM is scarce with no report on outcome parameters. Read More

View Article and Full-Text PDF
September 2021

A novel TPS toolkit to assess correlation between transit fluence dosimetry and DVH metrics for adaptive head and neck radiotherapy.

Phys Eng Sci Med 2021 Aug 31. Epub 2021 Aug 31.

Department of Physics, The University of Adelaide, Adelaide, SA, 5005, Australia.

Inter-fractional anatomical variations in head and neck (H&N) cancer patients can lead to clinically significant dosimetric changes. Adaptive re-planning should thus commence to negate any potential over-dosage to organs-at-risk (OAR), as well as potential under-dosage to target lesions. The aim of this study is to explore the correlation between transit fluence, as measured at an electronic portal imaging device (EPID), and dose volume histogram (DVH) metrics to target and OAR structures in a simulated environment. Read More

View Article and Full-Text PDF

Impact of CBCT frequency on target coverage and dose to the organs at risk in adjuvant breast cancer radiotherapy.

Sci Rep 2021 Aug 30;11(1):17378. Epub 2021 Aug 30.

Department of Radiation Oncology, Klinikum Rechts Der Isar, Medical School, Technical University Munich, Ismaningerstraße 22, 81675, Munich, Germany.

The current study aims to assess the effect of cone beam computed tomography (CBCT) frequency during adjuvant breast cancer radiotherapy with simultaneous integrated boost (SIB) on target volume coverage and dose to the organs at risk (OAR). 50 breast cancer patients receiving either non-hypofractionated or hypofractionated radiotherapy after lumpectomy including a SIB to the tumor bed were selected for this study. All patients were treated in volumetric modulated arc therapy (VMAT) technique and underwent daily CBCT imaging. Read More

View Article and Full-Text PDF

The impact of organ-at-risk contour variations on automatically generated treatment plans for NSCLC.

Radiother Oncol 2021 Aug 27;163:136-142. Epub 2021 Aug 27.

Department of Radiation Oncology (Maastro), GROW School for Oncology, Maastricht University Medical Centre+, Maastricht, The Netherlands.

Background And Purpose: Quality of automatic contouring is generally assessed by comparison with manual delineations, but the effect of contour differences on the resulting dose distribution remains unknown. This study evaluated dosimetric differences between treatment plans optimized using various organ-at-risk (OAR) contouring methods.

Materials And Methods: OARs of twenty lung cancer patients were manually and automatically contoured, after which user-adjustments were made. Read More

View Article and Full-Text PDF

An inverse planning simulated annealing algorithm with adaptive weight adjustment for LDR pancreatic brachytherapy.

Int J Comput Assist Radiol Surg 2021 Aug 28. Epub 2021 Aug 28.

School of Mechanical Engineering, Tianjin University, 135 Yaguan Road, Jinnan District, Tianjin, 300350, China.

Purpose: The inverse planning simulated annealing (IPSA) algorithm has shown good results in cancer surgical treatment planning. However, an adaptive approach has not well been proposed for different shapes and sizes of tumors. The purpose of this study was to propose an adaptive, efficient and safe algorithm to get high-quality treatment dose planning, which is presented for pancreatic cancer. Read More

View Article and Full-Text PDF

Simulated dose painting of hypoxic sub-volumes in pancreatic cancer stereotactic body radiotherapy.

Phys Med Biol 2021 Sep 9;66(18). Epub 2021 Sep 9.

Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, Canada.

Dose painting of hypoxic tumour sub-volumes using positron-emission tomography (PET) has been shown to improve tumour controlin several sites, predominantly head and neck and lung cancers. Pancreatic cancer presents a more stringent challenge, given its proximity to critical gastro-intestinal organs-at-risk (OARs), anatomic motion, and impediments to reliable PET hypoxia quantification. A radiobiological model was developed to estimate clonogen survival fraction (SF), usingF-fluoroazomycin arabinoside PET (FAZA PET) images from ten patients with unresectable pancreatic ductal adenocarcinoma to quantify oxygen enhancement effects. Read More

View Article and Full-Text PDF
September 2021

Prospects for daily online adaptive radiotherapy via ethos for prostate cancer patients without nodal involvement using unedited CBCT auto-segmentation.

J Appl Clin Med Phys 2021 Aug 25. Epub 2021 Aug 25.

Department of Radiation Medicine and Applied Sciences, University of California San Diego, La Jolla, California, USA.

Purpose:  Implementing new online adaptive radiation therapy technologies is challenging because extra clinical resources are required particularly expert contour review. Here, we provide the first assessment of Varian's Ethos™ adaptive platform for prostate cancer using no manual edits after auto-segmentation to minimize this impact on clinical efficiency.

Methods: Twenty-five prostate patients previously treated at our clinic were re-planned using an Ethos™ emulator. Read More

View Article and Full-Text PDF

Comparison of whole breast dosimetry techniques - From 3DCRT to VMAT and the impact on heart and surrounding tissues.

J Med Radiat Sci 2021 Aug 25. Epub 2021 Aug 25.

Radiation Oncology Department, Princess Alexandra Hospital, Cancer Services, Brisbane, Queensland, Australia.

Introduction: Various techniques for whole breast radiation therapy (WBRT) have been reported to increase dose to contralateral tissues. Heart dose is of critical importance as there is no apparent dose threshold below which there is no risk. The aim of this study was to compare planning techniques for WBRT that achieves the best target dosimetry and lowest organ at risk (OAR) dose. Read More

View Article and Full-Text PDF

A Planning Comparison of IMRT vs. Pencil Beam Scanning for Deep Inspiration Breath Hold Lung Cancers.

Med Dosim 2021 Aug 20. Epub 2021 Aug 20.

Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA.

Deep inspiration breath hold (DIBH) has dosimetric advantages for lung cancer patients treated with external beam therapy, but is difficult for many patients to perform. Proton therapy permits sparing of the downstream organs at risk (OAR). We compared conventionally fractionated proton (p) and photon(x) plans on both free breathing (FB) and DIBH planning CTs to determine the effect of DIBH with proton therapy. Read More

View Article and Full-Text PDF

Double-vertebral segment SBRT via novel ring-mounted Halcyon Linac: Plan quality, delivery efficiency and accuracy.

Med Dosim 2021 Aug 16. Epub 2021 Aug 16.

University of Kentucky, Department of Radiation Medicine, Lexington, KY, USA.

To evaluate the plan quality, treatment delivery efficiency, and accuracy of single-isocenter/multi-target (SIMT) volumetric modulated arc therapy (VMAT) of double-vertebral segments stereotactic body radiation therapy (SBRT) on Halcyon ring delivery system (RDS). In-house multi-target end-to-end phantom testing and independent dose verification using the MD Anderson's single-isocenter/multi-target (lung/spine targets) thorax phantom were completed. Six previously treated patients with 2-vertebral segments on thoracic and/or lumber spine were replanned on Halcyon RDS with 6MV-FFF beam using a single-isocenter placed between the vertebral segments. Read More

View Article and Full-Text PDF

AGITG MASTERPLAN: a randomised phase II study of modified FOLFIRINOX alone or in combination with stereotactic body radiotherapy for patients with high-risk and locally advanced pancreatic cancer.

BMC Cancer 2021 Aug 19;21(1):936. Epub 2021 Aug 19.

Department of Medical Oncology, Nelune Cancer Centre, Prince of Wales Hospital, Sydney, Australia.

Background: Among patients with non-metastatic pancreatic cancer, 80% have high-risk, borderline resectable or locally advanced cancer, with a 5-year overall survival of 12%. MASTERPLAN evaluates the safety and activity of stereotactic body radiotherapy (SBRT) in addition to chemotherapy in these patients.

Methods And Design: MASTERPLAN is a multi-centre randomised phase II trial of 120 patients with histologically confirmed potentially operable pancreatic cancer (POPC) or inoperable pancreatic cancer (IPC). Read More

View Article and Full-Text PDF

Volumetric prediction of breathing and slow drifting motion in the abdomen using radial MRI and multi-temporal resolution modeling.

Phys Med Biol 2021 09 3;66(17). Epub 2021 Sep 3.

Department of Radiation Oncology, University of Michigan, Ann Arbor, MI 48109, United States of America.

Abdominal organ motions introduce geometric uncertainties to radiotherapy. This study investigates a multi-temporal resolution 3D motion prediction scheme that accounts for both breathing and slow drifting motion in the abdomen in support of MRI-guided radiotherapy. Ten-minute MRI scans were acquired for 8 patients using a volumetric golden-angle stack-of-stars sequence. Read More

View Article and Full-Text PDF
September 2021