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Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists | Page 2

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https://read.qxmd.com/read/31079619/three-dimensional-printed-electron-beam-modifier-for-total-skin-electron-treatments
#21
S Diamantopoulos, I Kagkiouzis, G Patatoukas, E Kypraiou, V Kouloulias, E Efstathopoulos, K Platoni
Total Skin Electron Beam (TSEB) treatment, despite its proven effectiveness in skin malignancies, is a rather exhausting irradiation method, especially for feeble patients. In an effort to reduce treatment time by creating a clinically acceptable single TSEB field, various beam modifiers of different materials and shapes were tested. Using the TSEB immobilization device of our department and 3D printing technology, aluminum and thermoplastic modifiers were designed and constructed, according to the resulting profiles at treatment distance...
July 2019: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
https://read.qxmd.com/read/30738651/monte-carlo-dose-verification-for-a-single-isocenter-vmat-plan-in-multiple-brain-metastases
#22
Kento Hoshida, Fujio Araki, Takeshi Ohno, Hirofumi Tominaga, Kazuki Komatsu, Kentaro Tamura
The purpose of this study was to verify the accuracy of dose calculation algorithms of a treatment planning system for a single-isocenter volumetric modulated arc therapy (VMAT) plan in multiple brain metastases, by comparing the dose distributions of treatment planning system with those of Monte Carlo (MC) simulations. We used a multitarget phantom containing 9 acrylic balls with a diameter of 15.9 mm inside a Lucy phantom measuring 17 × 17 × 17 cm3 . Seven VMAT plans were created using the multitarget phantom: 1 multitarget plan (MTP) and 6 single target plans (STP)...
February 6, 2019: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
https://read.qxmd.com/read/30713000/dose-evaluation-of-mri-based-synthetic-ct-generated-using-a-machine-learning-method-for-prostate-cancer-radiotherapy
#23
Ghazal Shafai-Erfani, Tonghe Wang, Yang Lei, Sibo Tian, Pretesh Patel, Ashesh B Jani, Walter J Curran, Tian Liu, Xiaofeng Yang
Magnetic resonance imaging (MRI)-only radiotherapy treatment planning is attractive since MRI provides superior soft tissue contrast over computed tomographies (CTs), without the ionizing radiation exposure. However, it requires the generation of a synthetic CT (SCT) from MRIs for patient setup and dose calculation. In this study, we aim to investigate the accuracy of dose calculation in prostate cancer radiotherapy using SCTs generated from MRIs using our learning-based method. We retrospectively investigated a total of 17 treatment plans from 10 patients, each having both planning CTs (pCT) and MRIs acquired before treatment...
January 31, 2019: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
https://read.qxmd.com/read/30655170/end-to-end-testing-of-automatic-plan-optimization-using-raystation-scripting-for-hypofractionated-multimetastatic-brain-stereotactic-radiosurgery
#24
Eun Young Han, Gwe-Ya Kim, Neal Rebueno, Debra N Yeboa, Tina M Briere
For external beam stereotactic radiosurgery of multiple brain metastatic lesions, it is difficult to select optimal treatment isocenters because the orientation and volume of each planning target volume (PTV) and its proximity to critical structures are unique for each patient. The RayStation treatment planning system offers Python-based scripting to optimize the placement of the treatment isocenter by comparing scenario-based plans. This can improve the plan quality by reducing the dose to the normal brain and increasing planning efficiency...
January 14, 2019: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
https://read.qxmd.com/read/30642696/evaluation-of-the-correlation-between-prostatic-displacement-and-rectal-deformation-using-the-dice-similarity-coefficient-of-the-rectum
#25
Yoshinori Tanabe, Takayuki Ishida, Hidetoshi Eto, Tatsuhiro Sera, Yuki Emoto
To estimate the relationship between the three-dimensional (3D) displacement error of the prostate and rectal deformation for reduction of deviation between the planned and treatment dose, using multiple acquisition planning CT (MPCT) and the Dice similarity coefficient (DSC) for rectal deformation for treatment of patients with prostate cancer. The 3D displacement error between the pelvic bone and a matching fiducial marker was calculated using MPCT in 24 patients who underwent prostate volumetric-modulated arc therapy for prostate cancer...
January 11, 2019: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
https://read.qxmd.com/read/30639142/dosimetric-comparison-of-helical-tomotherapy-and-vmat-for-anal-cancer-a-single-institutional-experience
#26
Ian Gleeson, Christopher Rose, Joshua Spurrell
To compare the dosimetric results of helical tomotherapy (HT) and volumetric arc therapy (VMAT) in the treatment of anal cancer. Plans were created for 20 (n = 20) patients treated for anal cancer using HT and 2 arc VMAT. Dosimetric comparison was assessed for doses to targets and organs at risk (small bowel, bladder, external genitalia, and femoral heads). Delivery time and dosimetric verification results were also compared. HT showed a higher V95% for both primary and nodal targets (V95% increase by 0...
January 11, 2019: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
https://read.qxmd.com/read/30630654/feasibility-study-of-using-flattening-filter-free-photon-beams-to-deliver-conventional-flat-beams
#27
Nicholas J Potter, Sharon Lebron, Jonathan G Li, Chihray Liu, Bo Lu
Various dosimetric benefits such as increased dose rate, and reduced leakage and out of field dose have led to the growth of flattening-filter-free (FFF) technology in the clinic. In this study, we concentrate on investigating the feasibility of using FFF beams to deliver conventional flat beams, since completely getting rid of the flattening-filter module from the gantry head can not only simplify the gantry design but also decrease the workload on machine maintenance and quality assurance. Two intensity modulated radiotherapy techniques, step-and-shoot (S&S) and sliding window (SW), were used to generate flat beam profiles for 6 regular-shaped beams and 3 clinical beams while operating in FFF mode...
January 7, 2019: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
https://read.qxmd.com/read/30611624/usefulness-of-ezfluence-software-for-radiotherapy-planning-of-breast-cancer-treatment
#28
Todd Yoder, An Ting Hsia, Zhigang Xu, Alexander Stessin, Samuel Ryu
This study compared the EZFluence planning technique for irradiation of the breast with commonly used Field-in-Field (FiF) technique by analyzing the dose uniformity, the dose to the lung, heart, and other organs at risk, the total Monitor Unit (MU), and the time spent for planning. Two different 3-dimensional conformal dose plans were created for 20 breast cancer patients. Six patients were treated to a dose of 5000 cGy in 25 fractions and 14 were treated to a dose of 4256 cGy in 16 fractions. Average breast volume was 800 cc (range 128 to 1892 cc)...
January 2, 2019: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
https://read.qxmd.com/read/30598391/appropriate-treatment-planning-method-for-field-joint-dose-in-total-body-irradiation-using-helical-tomotherapy
#29
Keisuke Usui, Akira Isobe, Naoya Hara, Naoto Shikama, Keisuke Sasai, Koichi Ogawa
Total body irradiation (TBI) using helical tomotherapy (HT) has advantages over the standard linear accelerator-based approach to the conditioning regimen for hematopoietic cell transplantation. However, the radiation field has to be divided into two independent irradiation plans to deliver a homogeneous dose to the whole body. A clinical target volume near the skin increases the skin surface dose; therefore, high- or low-dose regions arise depending on the set-up position accuracy because the two radiation fields are somewhat overlapped or separated...
December 28, 2018: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
https://read.qxmd.com/read/30551844/dosimetric-comparison-of-vaginal-vault-brachytherapy-vs-applicator-guided-stereotactic-body-radiotherapy-with-volumetric-modulated-arc-therapy-and-helical-tomotherapy-for-endometrium-cancer-patients
#30
Berna Akkus Yildirim, Yemliha Dolek, Ozan Cem Guler, Gungor Arslan, Cem Onal
We performed this dosimetric study to compare a nonstandard volumetric modulated arc therapy (VMAT) and helical tomotherapy (HT) techniques with high-dose rate (HDR) brachytherapy (BRT) plan of vaginal vault in patients with postoperative endometrial cancer (EC). Twelve postoperative patients with early stage EC were included in this study. Three plans were performed for each patient; dosimetric and radiobiological comparisons were made using dose-volume histograms and equivalent dose for determining the planning target volume (PTV) coverages in brachytherapy and external beam radiotherapy, and organs-at-risk (OARs) doses between three different delivery techniques...
December 11, 2018: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
https://read.qxmd.com/read/30527834/a-statistics-based-model-for-prediction-of-achievability-of-the-planning-criteria-for-imrt-planning
#31
King Hang Wicger Wong, Hing Tong Lucullus Leung, Lai Wan Dora Kwong
The purpose of this study is to develop and evaluate a statistics-based model to predict the achievability of the planning criteria for intensity-modulated radiation therapy planning. A statistics-based model was proposed to predict the achievability of the planning criteria based on the structure set. A retrospective study was performed to validate the proposed model. A total of 160 prostate cases and 134 nasopharynx (NP) cases were used as the training set to build the model while 200 cases for each treatment site were used to validate the proposed model...
December 5, 2018: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
https://read.qxmd.com/read/30528259/effect-of-arc-length-on-skin-dose-from-hypofractionated-volumetric-modulated-arc-radiotherapy-treatments-of-the-lung-and-spine
#32
James Rijken, Tanya Kairn, Scott Crowe, Jamie Trapp
Due to large doses per fraction, stereotactic ablative radiotherapy of lung or spine can lead to skin tissue toxicity, the amount of which depends on a variety of factors such as target location, beam geometry, and immobilization. The effect of arc length on spreading out entrance and exit doses and the corresponding predictions of skin reactions has not yet been studied for stereotactic body radiotherapy volumetric modulated arc therapy (VMAT) treatments. 58 clinically relevant VMAT stereotactic body radiotherapy spine and lung plans were created for an anthropomorphic phantom utilizing a range of target locations, beam geometries and arc lengths...
December 4, 2018: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
https://read.qxmd.com/read/30522800/predictive-performance-of-an-ovh-based-treatment-planning-quality-assurance-model-for-prostate-vmat-assessing-dependence-on-training-cohort-size-and-composition
#33
Alex Burton, Craig Norvill, Martin A Ebert
Radiotherapy treatment planning quality assurance models are used to assess overall plan quality in terms of dose-volume characteristics, by predicting an optimal dosimetry based on a dataset of prior cases (the training cohort). In this study, a treatment planning quality assurance model for prostate cancer patients treated with volumetric modulated arc therapy was developed using the concept of the overlap volume histogram for geometric comparison to the training cohort. The model was developed on the publically available Erasmus iCycle dataset in order to remove the effect of plan quality/inter-planner variability on the model's predictive capabilities...
December 3, 2018: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
https://read.qxmd.com/read/30514600/imrt-planning-parameter-optimization-for-spine-stereotactic-radiosurgery
#34
Gabriel B Ayala, Kieu A Doan, Hie Ji Ko, Peter K Park, Edwin D Santiago, Shirly J Kuruvila, Amol J Ghia, Tina M Briere, Zhifei Wen
Spine stereotactic radiosurgery (SSRS) is a noninvasive treatment for metastatic spine lesions. MD Anderson Cancer Center reports a quality assurance (QA) failure rate approaching 15% for SSRS cases, which we hypothesized is due to difficulties in accurately calculating dose resulting from a large number of small-area segments. Clinical plans typically use 9 beams with an average of 10 segments per beam and minimum segment area of 2-3 cm2 . The purpose of this study was to identify a set of intensity-modulated radiation therapy (IMRT) planning parameters that attempts to optimize the balance among QA passing rate, plan quality, dose calculation accuracy, and delivery time for SSRS plans...
December 1, 2018: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
https://read.qxmd.com/read/30477750/selecting-noncoplanar-beam-directions-in-a-patient-coordinate-system-for-radiotherapy-planning
#35
Chuanmeng Niu, Minghui Li, Hui Yan, Chenlei Guo, Jianrong Dai
To introduce a beam angle selection method based on the patient coordinate system for treatment planning of noncoplanar intensity-modulated radiation therapy (IMRT). Traditionally, in radiotherapy planning, beam directions are selected in the machine coordinate system. A noncoplanar beam direction is established through a treatment table rotation followed by a gantry rotation. However, visualizing the beam direction relative to the patient is difficult. The suggestion here is to describe the beam direction in the patient coordinate system...
November 23, 2018: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
https://read.qxmd.com/read/30455092/dependence-of-volume-dose-indices-on-dose-calculation-algorithms-for-vmat-sbrt-plans-for-peripheral-lung-tumor
#36
Takanori Matsuoka, Fujio Araki, Takeshi Ohno, Junichi Sakata, Hirofumi Tominaga
The purpose of this study was to investigate the dependence of volume dose indices on dose calculation algorithms for volumetric modulated arc therapy (VMAT) for stereotactic body radiotherapy (SBRT) plans to treat peripheral lung tumors by comparing them with those of Monte Carlo (MC) calculations. VMAT-SBRT plans for peripheral lung tumors were created using the Eclipse treatment planning system (TPS) for 24 patients with nonsmall cell lung cancer. VMAT dose distributions for gross tumor volume (GTV), internal target volume (ITV), and planning target volume (PTV) were calculated using the analytical anisotropic algorithm (AAA), the Acuros XB (AXB) algorithm, and a MC algorithm...
November 16, 2018: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
https://read.qxmd.com/read/30396725/radiographic-predictors-of-imrt-for-treating-regional-lymph-nodes-in-breast-cancer
#37
Mary K Dean, William Amestoy, Cristiane Takita, Stuart E Samuels
Regional nodal irradiation (RNI) is an essential part of the treatment of high risk early stage (Stage IIb) and locally advanced (Stage III) breast cancer. Acceptable radiation plans can usually be achieved using 3-dimensional conformal radiation therapy with deep-inspiration breath hold to limit dose to the heart, although in some cases intensity-modulated radiation therapy produces superior results. The goal of this study is to identify radiographic parameters that predict the need for IMRT when delivering RNI...
November 2, 2018: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
https://read.qxmd.com/read/30389413/optimal-selection-of-optimization-bolus-thickness-in-planning-of-vmat-breast-radiotherapy-treatments
#38
Maija Rossi, Eeva Boman, Mika Kapanen
The aim of this study was to find an optimal optimization skin flash thickness in volumetric modulated arc radiotherapy of the breast in consideration of soft tissue deformations during the treatment course. Ten breast radiotherapy patients with axillary lymph node inclusion were retrospectively planned with volumetric modulated arc radiotherapy technique. The plans were optimized with the planning target volume (PTV) extending outside the skin contour by 0, 5, 7, and 10 mm; and with optimization boluses of 3 or 5 mm on the extended PTV...
October 30, 2018: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
https://read.qxmd.com/read/30529304/locoregional-irradiation-including-internal-mammary-nodal-region-for-left-sided-breast-cancer-after-breast-conserving-surgery-dosimetric-evaluation-of-4-techniques
#39
Yingjie Xu, Jingbo Wang, Zhihui Hu, Yuan Tian, Pan Ma, Shuai Li, Jianrong Dai, Shulian Wang
The present study aimed to compare 4 techniques in the planning of locoregional irradiation including internal mammary nodal region for left-sided breast cancer. Ten patients with left-sided breast cancer undergoing breast conservation surgery were enrolled. For each patient, 4 treatment plans were performed: a helical tomotherapy (HT) plan, a volumetric modulated arc therapy (VMAT) plan, a static intensity modulated radiation therapy (IMRT) plan, and a hybrid IMRT plan, designed to encompass the whole breast, internal mammary, and supraclavicular nodal regions...
October 24, 2018: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
https://read.qxmd.com/read/30366620/nasopharyngeal-carcinoma-radiotherapy-with-hybrid-technique
#40
Ugur Akbas, Canan Koksal, Nazmiye Donmez Kesen, Kubra Ozkaya, Hatice Bilge, Musa Altun
The aim of the study was to investigate the effect of the Hybrid technique which was created by combining of intensity modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) for the treatment of nasopharyngeal cancer (NPC) patients. 7 to 9 field IMRT, triple arc VMAT, and Hybrid plans were generated for 10 advanced stage NPC patients. The homogeneity index (HI) and the conformity index (CI) of planning target volumes (PTVs) were calculated for each technique to evaluate the plan quality. The techniques were compared in terms of plan quality, sparing of organs at risk (OARs), monitor units (MUs), and delivery time...
October 23, 2018: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
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