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Journal of Medical Physics

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https://read.qxmd.com/read/30636853/determination-and-analysis-of-film-reject-rate-at-eight-selected-governmental-diagnostic-x-ray-facilities-in-tigray-region-northern-ethiopian
#1
Messele Yisak Arbese, T Demissie Abebe, B Abraha Mesele
Background: In radiography examination, it is common to encounter patients undergoing repeated X-ray exposure after the rejection of a film image due to poor image quality. This subjects the patients to unnecessary radiation exposure and extra cost for the facility. This fact has required to investigate the causes of film rejection in common X-ray examinations. Aims: This study aims to obtain images, which are adequate for the clinical diagnostic purpose with minimum radiation dose to the patient in X-ray radiographic examination using film rejects analysis...
October 2018: Journal of Medical Physics
https://read.qxmd.com/read/30636852/verification-of-treatment-planning-algorithms-using-optically-stimulated-luminescent-dosimeters-in-a-breast-phantom
#2
Zhenia Gopalakrishnan, Raghuram K Nair, P Raghukumar, Sharika V Menon, Saju Bhasi
Aim: The aim of this study is to measure and compare the surface dose of treated breast and contralateral breast with the treatment planning system (TPS) calculated dose using calibrated optically stimulated luminescent dosimeter (OSLD) in an indigenous wax breast phantom. Materials and Methods: Three-dimensional conformal plans were generated in eclipse TPS v. 13 to treat the left breast of a wax phantom for a prescribed dose of 200 cGy. The plans were calculated using anisotropic analytical algorithm (AAA) and Acuros algorithm with 1-mm grid size...
October 2018: Journal of Medical Physics
https://read.qxmd.com/read/30636851/imaging-and-dosimetric-study-on-direct-flat-panel-detector-based-digital-mammography-system
#3
Reena Sharma, S D Sharma, P S Sarkar, D Datta
Introduction: Image quality of digital mammography system is generally defined by three primary physical parameters, namely, contrast, resolution, and noise. Quantification of these metrics can be done by measuring objective image quality parameters defined as contrast-to-noise ratio (CNR), modulation transfer function (MTF), and noise power spectra (NPS). Materials and Methods: In the present study, various imaging metrics such as CNR, contrast detail resolution, MTF, and NPS were evaluated for a direct flat-panel detector-based digital mammography system following the European Guidelines...
October 2018: Journal of Medical Physics
https://read.qxmd.com/read/30636850/dosimetric-characterization-of-an-intensity-modulated-x-ray-brachytherapy-system
#4
Sung-Woo Lee, Evgeny Sozontov, Emil Strumban, Fang-Fang Yin
Purpose: An intensity-modulated X-ray brachytherapy system is being developed for various clinical applications. This new system makes it possible for clinical staff to control energy as well as dose rate for different tumor sites according to their sizes and radiobiological characteristics. Materials and Methods: This system is mainly composed of an X-ray tube, guide tube collimation, and secondary (pseudo) target. Due to its configuration, convenient modulations of fluorescent X-ray energy and intensity are possible...
October 2018: Journal of Medical Physics
https://read.qxmd.com/read/30636849/dosimetry-effects-caused-by-unilateral-and-bilateral-hip-prostheses-a-monte-carlo-case-study-in-megavoltage-photon-radiotherapy-for-computed-tomography-data-without-metal-artifacts
#5
Courage Mahuvava, Frederik Carl Phillipus Du Plessis
Background: Hip prostheses (HPs) are routinely used in hip augmentation to replace painful or dysfunctional hip joints. However, high-density and high-atomic-number (Z) inserts may cause dose perturbations in the target volume and interface regions. Aim: To evaluate the dosimetric influence of various HPs during megavoltage conformal radiotherapy (RT) of the prostate using Monte Carlo (MC) simulations. Materials and Methods: BEAMnrc and DOSXYZnrc MC user-codes were respectively used to simulate the linac head and to calculate 3D absorbed dose distributions in a computed tomography (CT)-based phantom...
October 2018: Journal of Medical Physics
https://read.qxmd.com/read/30636848/comparison-of-interfractional-setup-reproducibility-between-two-types-of-patient-immobilization-devices-in-image-guided-radiation-therapy-for-prostate-cancer
#6
Shoki Inui, Yoshihiro Ueda, Shingo Ohira, Masaru Isono, Akira Masaoka, Seiya Murata, Yuya Nitta, Tsukasa Karino, Masayoshi Miyazaki, Teruki Teshima
Purpose: The aim of this study is to compare the interfractional setup reproducibility of two types of patient immobilization devices for prostate cancer receiving image-guided radiation therapy (IGRT). Materials and Methods: The MOLDCARE (MC) involves hydraulic fixation, whereas the BlueBAG (BB) and Vac-Lock (VL) involve vacuum fixation. For 72 patients, each immobilization device was individually customized during computed tomography (CT) simulation. Before the treatment, bony registration was performed using orthogonal kV images and digitally reconstructed radiographs...
October 2018: Journal of Medical Physics
https://read.qxmd.com/read/30636847/experimental-assessment-of-proton-dose-calculation-accuracy-in-small-field-delivery-using-a-mevion-s250-proton-therapy-system
#7
Kyle D DePew, Salahuddin Ahmad, Hosang Jin
Purpose: Dose calculation accuracy of the Varian Eclipse treatment planning system (TPS) is empirically assessed for small-aperture fields using a Mevion S250 double scattering proton therapy system. Materials and Methods: Five spherical pseudotumors were modeled in a RANDO head phantom. Plans were generated for the targets with apertures of 1, 2, 3, 4, or 5 cm diameter using one, two, and three beams. Depth-dose curves and lateral profiles of the beams were taken with the planned blocks and compared to Eclipse calculations...
October 2018: Journal of Medical Physics
https://read.qxmd.com/read/30636846/evaluation-of-plan-quality-metrics-in-stereotactic-radiosurgery-radiotherapy-in-the-treatment-plans-of-arteriovenous-malformations
#8
Sharika Venugopal Menon, Raghukumar Paramu, Saju Bhasi, Raghuram Kesavan Nair
Aim: Several plan quality metrics are available for the evaluation of stereotactic radiosurgery/radiotherapy plans. This is a retrospective analysis of 60 clinical treatment plans of arteriovenous malformation (AVM) patients to study clinical usefulness of selected plan quality metrics. Materials and Methods: The treatment coverage parameters Radiation Therapy Oncology Group (RTOG) Conformity Index (CIRTOG ), RTOG Quality of Coverage (QRTOG ), RTOG Homogeneity Index (HIRTOG ), Lomax Conformity Index (CILomax ), Paddick's Conformity Index (CIPaddick ), and dose gradient parameters Paddick's Gradient Index (GIPaddick ) and Equivalent Fall-off Distance (EFOD) were calculated for the cohort of patients...
October 2018: Journal of Medical Physics
https://read.qxmd.com/read/30636845/study-to-compare-the-effect-of-different-registration-methods-on-patient-setup-uncertainties-in-cone-beam-computed-tomography-during-volumetric-modulated-arc-therapy-for-breast-cancer-patients
#9
P Mohandass, D Khanna, T Manoj Kumar, T Thiyagaraj, C Saravanan, Narendra Kumar Bhalla, Abhishek Puri
Purpose: This study compared three different methods used in registering cone-beam computed tomography (CBCT) image set with planning CT image set for determining patient setup uncertainties during volumetric modulated arc therapy (VMAT) for breast cancer patients. Materials and Methods: Seven breast cancer patients treated with 50 Gy in 25 fractions using VMAT technique were chosen for this study. A total of 105 CBCT scans were acquired by image guidance protocol for patient setup verification...
October 2018: Journal of Medical Physics
https://read.qxmd.com/read/30305779/assessment-of-diagnostic-reference-level-in-radiography-of-neonatal-chest-anteroposterior-examination-a-hospital-based-study
#10
Jibon Sharma, Jogesh Sarma, Sushant Agarwal
Radiological imaging is an important modality of today's overall practicum. Imaging can begin as early as the 1st day of life. Neonates are 3-4 times more sensitive to radiation than adults. The purpose of the work was to assess the diagnostic reference level (DRL), the radiation organ dose, and effective organ dose for both sexes from chest anteroposterior radiograph, which is the most common radiographic examination performed at the Neonatal Intensive Care Unit (NICU). The entrance air kerma was measured using a solid-state PIN type detector, and the value was used as the input factor to PCXMC-2...
July 2018: Journal of Medical Physics
https://read.qxmd.com/read/30305778/monte-carlo-simulation-on-the-imaging-contrast-enhancement-in-nanoparticle-enhanced-radiotherapy
#11
Ferdos Albayedh, James C L Chow
This study focused on the imaging in radiotherapy by finding the relationship between the imaging contrast ratio and appropriate gold, iodine, iron oxide, silver, and platinum nanoparticle concentrations; the relationship between the imaging contrast ratio and different beam energies for the different nanoparticle concentrations; the relationship between the contrast ratio and various beam energies for gold nanoparticles; and the relationship between the contrast ratio and different thicknesses of the incident layer of the phantom including variety of gold nanoparticles (GNPs) concentration...
July 2018: Journal of Medical Physics
https://read.qxmd.com/read/30305777/optimization-of-variance-reduction-techniques-used-in-egsnrc-monte-carlo-codes
#12
Sangeetha Shanmugasundaram, Sureka Chandrasekaran
Monte Carlo (MC) simulations are often used in calculations of radiation transport to enable accurate prediction of radiation-dose, even though the computation is relatively time-consuming. In a typical MC simulation, significant computation time is allocated to following non-important events. To address this issue, variance reduction techniques (VRTs) have been suggested for reducing the statistical variance for the same computation time. Among the available MC simulation codes, electron gamma shower (National Research Council of Canada) (EGSnrc) is a general-purpose coupled electron-photon transport code that also features an even-handed, rich set of VRTs...
July 2018: Journal of Medical Physics
https://read.qxmd.com/read/30305776/a-pilot-study-on-the-comparison-between-planning-target-volume-based-intensity-modulated-proton-therapy-plans-and-robustly-optimized-intensity-modulated-proton-therapy-plans
#13
Bojarajan Perumal, Harikrishna Etti Sundaresan, Ranganathan Vaitheeswaran
The objective of this work is to compare the planning target volume (PTV)-based intensity-modulated proton therapy (IMPT) plans with robustly optimized IMPT plans using the robust optimization tools available in Pinnacle Treatment Planning System. We performed the study in five cases of different anatomic sites (brain, head and neck, lung, pancreas, and prostate). Pinnacle IMPT nonclinical version was used for IMPT planning. Two types of IMPT plans were created for each case. One is PTV-based conventionally optimized IMPT plan and the other is robustly optimized plan considering setup uncertainties...
July 2018: Journal of Medical Physics
https://read.qxmd.com/read/30305775/dosimetry-of-175-ytterbium-poly-amidoamine-therapy-for-humans-organs
#14
Navideh Aghaei-Amirkhizi, Sodeh Sadjadi, Leila Moghaddam-Banaem, Mitra Athari-Allaf, Fariba Johari-Deha
Purpose: This investigation focuses on biodistribution of irradiated dendrimer encapsulated ytterbium-175 (175 Yb) and to estimate the absorbed dose from intravenous injection of PAMAM encapsulated 175 Yb to human organs. Methods: A dendrimer compound containing an average of 55 Yb+3 ions per dendrimer was prepared and irradiated with neutrons for 2h at 3×1011 n.cm-2 s-1 neutron flux. The resulting mixture was injected into a group of tumor bearing mice and the mice were excised, weighed and counted at certain times to study the biodistribution...
July 2018: Journal of Medical Physics
https://read.qxmd.com/read/30305774/incidence-of-suboptimal-applicator-placement-and-the-resulting-dosimetric-impact-in-image-based-intracavitary-brachytherapy
#15
Ramya Rangarajan
Aim: With the advent of computed tomography (CT)-based brachytherapy, it is possible to view the appropriate placement of the applicator within the uterine canal and detect uterine perforation. In this study, the incidence of suboptimal placement of the intracavitary applicator and the resulting dosimetric impact were analyzed and compared with a similar set of ideal applicator placement. Materials and Methods: CT datasets of 282 (141 patients) high dose rate brachytherapy insertions between January and April 2016 were analyzed...
July 2018: Journal of Medical Physics
https://read.qxmd.com/read/30305773/comparison-of-measured-and-monte-carlo-calculated-dose-distributions-from-indigenously-developed-6-mv-flattening-filter-free-medical-linear-accelerator
#16
Bibekananda Mishra, Subhalaxmi Mishra, T Palani Selvam, S T Chavan, S N Pethe
Purpose: Monte Carlo simulation was carried out for a 6 MV flattening filter-free (FFF) indigenously developed linear accelerator (linac) using the BEAMnrc user-code of the EGSnrc code system. The model was benchmarked against the measurements. A Gaussian distributed electron beam of kinetic energy 6.2 MeV with full-width half maximum of 1 mm was used in this study. Methods: The simulation of indigenously developed linac unit has been carried out by using the Monte Carlo-based BEAMnrc user-code of the EGSnrc code system...
July 2018: Journal of Medical Physics
https://read.qxmd.com/read/30305772/voxel-based-bed-and-eqd-2-evaluation-of-the-radiotherapy-treatment-plan
#17
Gaganpreet Singh, Arun S Oinam, Rose Kamal, Bhumika Handa, Vivek Kumar, Bhavana Rai
Introduction: Three-dimensional (3D) treatment planning of patient undergoing radiotherapy uses complex and meticulous computational algorithms. These algorithms use 3D voxel data of the patient to calculate the radiation dose distribution and display it over the CT image dataset for treatment plan evaluation. Aims and Objective: The purpose of the present study is the development and implementation of radiobiological evaluation of the radiotherapy treatment plan incorporating the tissue-specific radiobiological parameters...
July 2018: Journal of Medical Physics
https://read.qxmd.com/read/30305771/a-dose-falloff-gradient-study-in-rapidarc-planning-of-lung-stereotactic-body-radiation-therapy
#18
Ganesh Narayanasamy, Dharmin Desai, Sanjay Maraboyina, Jose Penagaricano, Robert Zwicker, Ellis Lee Johnson
Introduction: Radiation Therapy Oncology Group (RTOG) report #0813 and 0915 recommends using D2cm and R50% as plan quality metrics for evaluation of normal tissue sparing in stereotactic body radiation therapy (SBRT) of lung lesion. This study introduces dose falloff gradient (DFG) as a tool for analyzing the dose beyond the planning target volume (PTV) extending into normal tissue structures. In ascertaining the impact of PTV size and SBRT planning techniques in DFG, this study questions the independence of the RTOG recommended metrics...
July 2018: Journal of Medical Physics
https://read.qxmd.com/read/29962694/erratum-magnetic-resonance-imaging-for-adaptive-cobalt-tomotherapy-a-proposal
#19
(no author information available yet)
[This corrects the article on p. 242 in vol. 31, PMID: 21206640.].
April 2018: Journal of Medical Physics
https://read.qxmd.com/read/29962693/documentation-of-a-new-intracavitary-applicator-for-transrectal-hyperthermia-designed-for-prostate-cancer-cases-a-phantom-study
#20
Vassilis Kouloulias, Aggeliki Nikolakopoulou, Irene Karanasiou, Christos Antypas, Christina Armpilia, Nikolaos Uzunoglou
Concerning clinical trials, intracavitary hyperthermia has already shown antitumor activity and has a potential role in the treatment of prostate cancer. The aim of this study was to document a new intracavitary applicator operating at 433 MHz, designed for transrectal hyperthermia, as well as to assess the specific absorption rate (SAR) distributions in terms of temperature measurements in a soft-tissue phantom. The microwave applicator consists of a dipole-type λ/2, a reflector, and the cooling system. The applicator was placed into a soft-tissue gel-phantom box that was mimicking the dielectric properties of the normal tissue...
April 2018: Journal of Medical Physics
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