Journal of Medical Physics

PURPOSE: According to the revised Task Group number 43 recommendations, a brachytherapy source must be validated against a similar or identical source before its clinical application. The purpose of this investigation is to verify the dosimetric data of the high dose rate (HDR) BEBIG 192 Ir source (Ir2.A85-2). MATERIALS AND METHODS: The HDR 192 Ir encapsulated seed was simulated and its main dosimetric data were calculated using Geant4 Application for Tomographic Emission (GATE) simulation code...

Monte Carlo (MC) techniques have been recognized as the gold standard for the simulation of radiation transport in radiotherapy. The aim of the study is to perform dosimetric evaluation of Simultaneous Integrated Boost (SIB) radiation treatment planning using MC simulation approach. The geometrical source modeling and simulation of 6 MV Flattening Filter Free (FFF)beam from TrueBeam linear accelerator have been carried out to simulate Volumetric Modulated Arc Therapy (VMAT) plans using MC simulation software PRIMO...

AIMS: Analysis of colonoscopy images is an important diagnostic procedure in the identification of colorectal cancer. It has been observed that owing to advancements in technology, numerous machine-learning models now excel in the analysis of colorectal polyps classification. This work focused on developing a framework that can classify polyps using images during colonoscopy. MATERIALS AND METHODS: First, the images were corrected by removing their spectral reflection...

AIM: This article aimed to present the salient features of the in-house developed Java program for the determination of inflection point and dosimetric parameters of flattening filter-free (FFF) photon beam. Reference levels for the dosimetric parameters of the FFF photon beams were also presented. MATERIALS AND METHODS: Beam profiles of 6 MV FFF and 10 MV FFF photon beams for a collimator setting of 20 cm × 20 cm measured at 10 cm depth in an isocentric setup acquired from various institutions were analyzed using an in-house developed Java program and manual method...

PURPOSE: The high-energy proton produces the unwanted dose contribution from the secondary neutron. The main purpose of this study is to report the validation results of in-house neutron moderator based on poly allyl diglycol carbonate (CR-39) detector, Chulalongkorn University Neutron Moderator (CUMOD) through the ambient dose equivalent, H *(10) measurement. MATERIALS AND METHODS: The Particle and Heavy Ion Transport code System (PHITS) Monte Carlo code was used to simulate the neutron response function...

INTRODUCTION: All building materials of natural origin contain some amounts of primordial radionuclides, 40 K, 232 Th, and 238 U, as well as other radionuclides in the decay series of 232 Th and 238 U. PURPOSE: The use of tiles to beautify walls and floors in dwellings has become popular worldwide and in Nigeria in particular. However, not much has been done in assessing the impact of the use of floor and wall tiles on the radiation exposure of dwellers. In this study, radioisotopes of natural origin (226 Ra, 232 Th, and 40 K) in selected ceramic tiles often used in Ibadan Southwest Nigeria were estimated and the associated radiological parameters evaluated...

PURPOSE: The focus of this work was given on the relative stopping power (RSP) using the water equivalent thickness (WET) validation on tissue substitutes and real pig organs, as well as a dosimetric comparison of proton treatment plans between single-energy computed tomography (SECT) and dual-energy computed tomography (DECT)-based dose calculations. MATERIALS AND METHODS: The CT calibration curve of SECT and DECT data was generated using the stoichiometric calibration method...

PURPOSE: The purpose of the study was to investigate the dosimetric characteristics of radiophotoluminescent glass dosimeters (RGDs) for pencil beam scanning proton therapy. The RGD's end-to-end testing of intensity-modulated proton therapy (IMPT) plans was also evaluated. MATERIALS AND METHODS: The dosimetric characteristics of the GD-302M type glass dosimeter were studied in terms of uniformity, short-term and long-term reproducibility, stability of the magazine position readout, dose linearity in the range from 0...

This article aims to identify, through a literature review, the best intensity-modulated technique (IMRT)/volumetric-modulated arc therapy (VMAT) for the breast/chest wall (Br/CW) as a function of the treatment planning system (TPS) and present the institutional dosimetric data for the same. A PubMed search was conducted following intensity-modulated irradiation techniques (IMRT) presented in the study: field-in-field (FiF), tangential IMRT (t-IMRT), multi-field IMRT, tangential VMAT (t-VMAT), half-arc VMAT (HA-VMAT), and large arc VMAT (LA-VMAT)...

PURPOSE: Rising cancer incidences, complex treatment techniques, and workflows have all impacted the radiotherapy scheduling process. Intelligent appointment scheduling is needed to help radiotherapy users adapt to new practices. MATERIALS AND METHODS: We utilized van Herk's safety margin formula to determine the radiotherapy department's treatment scheduling window (TSW). In addition, we examined the influence of in-room imaging on linac occupancy time (LOT). Varian Aria™ software version 15...

The study aimed to compute the effective dose (E) and size-specific dose estimate (SSDE) of routine adult patients undergoing thorax and abdominal computed tomography (CT) imaging and to present their multivariate analysis. All adult thorax and abdominal CT examinations conducted from March 2022 to June 2022 were prospectively included in this study. The Water Equivalent Diameter ( Dw ) and SSDE of all the examinations were computed from CT dose index volume ( CTDIvol ) and Dose length product (DLP) displayed on the dose report in the CT console...

AIMS: We investigated imaging dose and noise under clinical scan conditions at multiple institutions using a simple and unified method, and demonstrated the need for diagnostic reference levels in image-guided radiotherapy (IGRT). MATERIALS AND METHODS: Nine cone-beam and helical computed tomography (CT) scanners (Varian, Elekta, Accuray Inc., and BrainLAB) from seven institutions were investigated in this study. The weighted cone-beam dose index (CBDIw ) was calculated for head and pelvic protocols using a 100 mm pencil chamber under the conditions used in actual clinical practice at each institution...

PURPOSE: In our institution, stereotactic radiosurgery of multiple brain metastases is performed with the CyberKnife® (CK) device, using fixed/Iris collimators. In this study, nineteen fixed/Iris plans were recalculated with the multileaf collimator (MLC), to assess if it is possible to produce plans with comparable dosimetric overall quality. MATERIALS AND METHODS: For consistent comparisons, MLC plans were re-optimized and re-normalized in order to achieve the same minimum dose for the total planning target volume (PTVtot )...

BACKGROUND: The aim of the current study was to compare three different dose-calculating algorithms, i.e., superposition (SP), fast SP (FSP), and convolution (CV), for breast cancer patients treated with intensity-modulated radiotherapy (IMRT) and field-in-Field forward plan IMRT (FiF-FP-IMRT). MATERIALS AND METHODS: The current retrospective study involved 100 postmastectomy breast cancer patients who were given radiotherapy using IMRT and FiF-FP-IMRT planning techniques...

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OBJECTIVE: To examine the dosimetric characteristics of circular cones, the accuracy of dose modeling and overall treatment delivery of two radiosurgery systems integrated on a linear accelerator (Linac). MATERIALS AND METHODS: The dosimetric characteristics of circular cones (4-17.5 mm) from Varian (VC) and BrainLAB (BLC) were measured for 6 MV flattening filter free beam from Edge linac using stereotactic field diode and 0.65 cc ionization chamber following established protocols...

AIM: The main objective of this work is to propose an efficient segmentation model for accurate and robust lung segmentation from computed tomography (CT) images, even when the lung contains abnormalities such as juxtapleural nodules, cavities, and consolidation. METHODOLOGY: A novel deep learning-based segmentation model, pyramid-dilated dense U-Net (PDD-U-Net), is proposed to directly segment lung regions from the whole CT image. The model is integrated with pyramid-dilated convolution blocks to capture and preserve multi-resolution spatial features effectively...

An extended version of task group report (TG)-119 dosimetric tests was introduced and tested on the TrueBeam linear accelerator setup. Treatment plan results and quality assurance (QA) results of RapidArc (RA) and intensity-modulated radiotherapy (IMRT) were compared to understand the limitation and efficacy of the RA and IMRT system of the linear accelerator. Test structure sets were drawn on OCTAVIUS four-dimensional (4D) phantom computed tomography scan data for this study. We generated treatment plans based on the specified goal in the Eclipse™ treatment planning system using RA and IMRT in the study phantom...

PURPOSE: Volumetric modulated arc therapy (VMAT) has been increasingly used for cancer patients due to the fast delivery and improved dose conformity. Adaptive radiotherapy (ART) can significantly decrease dose to normal tissues and allow for dose escalation. However, current imaging techniques cannot provide four-dimensional (4D) patient anatomy or dose information during VMAT, which is critical for ART that involves respiratory motion. A novel imaging tool named VMAT-computed tomography (VMAT-CT) has the potential to reveal intra-fractional patient information...

PURPOSE: Optimizers are widely utilized across various domains to enhance desired outcomes by either maximizing or minimizing objective functions. In the context of deep learning, they help to minimize the loss function and improve model's performance. This study aims to evaluate the accuracy of different optimizers employed for autosegmentation of non-small cell lung cancer (NSCLC) target volumes on thoracic computed tomography images utilized in oncology. MATERIALS AND METHODS: The study utilized 112 patients, comprising 92 patients from "The Cancer Imaging Archive" (TCIA) and 20 of our local clinical patients, to evaluate the efficacy of various optimizers...