Changes in the linear attenuation coefficient of polymer gel dosimeters post-irradiation enable imaging dose distributions by x-ray computed tomography (CT). Various compositions manufactured from acrylamide (AA), and N,N'-methylene-bis-acrylamide (BIS) comonomers gelatin or agarose gelling agents were investigated. This work shows that increasing comonomer concentration increases CT-dose sensitivity dosimeter. can be further increased replacing with agarose. Varying however does not...

Purpose: This work introduces the concept of very small field size. Output factor (OPF) measurements at these sizes require extremely careful experimental methodology including measurement dosimetric size same time as each OPF measurement. Two quantifiable scientific definitions threshold are presented. Methods: A practical definition was established by quantifying effect that a 1 mm error in or detector position had on OPFs and setting acceptable uncertainties 1%. Alternatively, for...

The goal of this work was to set out a methodology for measuring and reporting small field relative output assess the application published correction factors across population linear accelerators.Measurements were made at 6 MV on five Varian iX accelerators using two PTW T60017 unshielded diodes. Relative readings profile measurements nominal square sizes side 0.5 1.0 cm. actual in-plane (A) cross-plane (B) widths taken be FWHM 50% isodose level. An effective size, defined as √FS eff=A · B,...

Purpose: Small field x‐ray beam dosimetry is difficult due to lack of lateral electronic equilibrium, source occlusion, high dose gradients, and detector volume averaging. Currently, there no single definitive recommended for small dosimetry. The objective this work was evaluate the performance a new commercial synthetic diamond detector, namely, PTW 60019 microDiamond, fields as used in stereotactic radiosurgery (SRS). Methods: sizes were defined by BrainLAB circular cones (4–30 mm...

This study aimed to provide a detailed evaluation and comparison of range modulated beam metrics, in terms their correlation with QA testing results variation between treatment sites, for large number treatments. Ten metrics including the modulation index (MI), fluence map complexity, complexity score (MCS), mean aperture displacement (MAD) small (SAS) were evaluated 546 beams from 122 intensity radiotherapy (IMRT) volumetric arc therapy (VMAT) plans targeting anus, rectum, endometrium,...

Due to their small collecting volume, diodes are commonly used in field dosimetry. However, the relative sensitivity of a diode increases with decreasing size. Conversely, air gaps have been shown cause significant decrease detector as size is decreased. Therefore, this study uses Monte Carlo simulations look at introducing upstream such that they measure constant across all sizes Varying thicknesses were introduced onto end two commercial (PTW 60016 photon and PTW 60017 electron diode),...

Abstract The number and complexity of transcatheter procedures continue to increase, raising concerns regarding radiation exposure patients staff. Procedures such as transaortic valve implantations (TAVI) have led cardiologists adopting higher dose techniques, digital subtraction angiography (DSA). This study compared the estimated patient occupational eye during coronary (CA), percutaneous intervention (PCI), TAVI workups (TWU), TAVI, endovascular aneurysm repairs (EVAR), other peripheral...

Post-irradiation changes in the linear attenuation coefficient, μ, of polymer gel dosimeters give rise to a change which can be measured with x-ray computed tomography. Polymer were manufactured consisting 3% (by weight) acrylamide and N,N'-methylene-bis-acrylamide comonomers dissolved aqueous gelatin (5% by total weight 89% de-ionized distilled water). μ was collimated radiation beam photons from an 241Am source. Density, ρ, using volumetric flasks capillary stoppers. The post-irradiation...

The purpose of this study was to investigate the effect very small air gaps (less than 1 mm) on dosimetry photon fields used for stereotactic treatments. Measurements were performed with optically stimulated luminescent dosimeters (OSLDs) 6 MV photons a Varian 21iX linear accelerator Brainlab µMLC attachment square field sizes down mm × mm. Monte Carlo simulations using EGSnrc C++ user code cavity. It found that model in accurately simulated OSLD measurements accelerator. For size, 0.5 gap...

Purpose: The aim of this work was to use a multicenter audit modulated radiotherapy quality assurance (QA) data provide practical examination gamma evaluation criteria and action level selection. the method for patient‐specific pretreatment QA is widespread, with most commercial solutions implementing method. Methods: Gamma agreement indices were calculated using 1%/1 mm, 2%/2 2%/3 3%/2 3%/3 5%/3 mm 1265 measurements, planned at seven treatment centers, four different planning systems,...

Purpose: An experimental extrapolation technique is presented, which can be used to determine the relative output factors for very small x-ray fields using Gafchromic EBT3 film. Methods: Relative were measured Brainlab SRS cones ranging in diameters from 4 30 mm2 on a Novalis Trilogy linear accelerator with 6 MV x-rays. The factor was determined an reducing circular region of interest (ROI) developed remove effects volume averaging. This achieved by scanning film measurements high resolution...

Navigation through tessellated solids in GEANT4 can degrade computational performance, especially if the solid is large and comprised of many facets. Redefining a as mesh tetrahedra common other techniques such finite element analysis computations need only consider local tetrahedrons rather than whole. Here within we describe technique that allows for automatic tetrahedral meshing subsequent loading these meshes assembly volumes; nested also examined. As makes geometry suitable optimization...

This study used automated data processing techniques to calculate a set of novel treatment plan accuracy metrics, and investigate their usefulness as predictors quality assurance (QA) success failure. A small sample 151 beams from 23 prostate cranial IMRT plans were in this study. These had been evaluated before using measurements with diode array system. The TADA software suite was adapted allow automatic batch calculation several proposed including mean field area, small-aperture, off-axis...

Purpose: A modification of the existing PVA‐FX hydrogel has been made to investigate use a functionalised polymer in Fricke gel dosimetry system decrease Fe 3+ diffusion. Methods: The chelating agent, xylenol orange, was chemically bonded gelling polyvinyl alcohol (PVA) create orange PVA (XO‐PVA). created from XO‐PVA (20% w/v) with ferrous sulfate (0.4 mM) and sulfuric acid (50 mM). Results: This resulted an optical density dose sensitivity 0.014 Gy −1 , auto‐oxidation rate 0.0005 h...

Abstract Background The automated and integrated machine performance check ( MPC ) tool was verified against independent detectors to evaluate its beam uniformity output detection abilities consider it suitable for daily quality assurance QA ). Methods Measurements were carried out on six linear accelerators (each located at individual sites) using clinically available photon electron energies a period up 12 months (n = 350). Daily constancy checks symmetry compared devices such as the SNC...