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The effects of mega-voltage CT scan parameters on offline adaptive radiation therapy
AbstractTomoTherapy involves image-guided radiation therapy (IGRT) using Mega-voltage CT (MVCT) for each treatment session. The acquired MVCT images can be utilized for the retrospective assessment of dose distribution. The TomoTherapy provides 18 distinct imaging conditions that can be selected based on a combination of algorithms, acquisition pitch, and slice interval. We investigated the accuracy of dose calculation and deformable image registration (DIR) depending on MVCT scan parameters and their effects on adaptive radiation therapy (ART). We acquired image values for density calibration tables (IVDTs) under 18 diffe...
Source: Radiological Physics and Technology - February 9, 2024 Category: Physics Source Type: research

Evaluation of attenuation correction method for head holder in brain perfusion single-photon emission computed tomography
AbstractHead holder attenuation affects brain perfusion single-photon emission computed tomography (SPECT) image quality. Here, we proposed a head holder-attenuation correction (AC) method using attenuation coefficient maps calculated by Chang ’s method from CT images. Then, we evaluated the effectiveness of the head holder-AC method by numerical phantom and clinical cerebral perfusion SPECT studies. In the numerical phantom, the posterior counts were 10.7% lower than the anterior counts without head holder-AC method. However, by perfor ming head holder-AC, the posterior count recovered by approximately 6.8%, approaching...
Source: Radiological Physics and Technology - February 9, 2024 Category: Physics Source Type: research

Deep learning-based PET image denoising and reconstruction: a review
AbstractThis review focuses on positron emission tomography (PET) imaging algorithms and traces the evolution of PET image reconstruction methods. First, we provide an overview of conventional PET image reconstruction methods from filtered backprojection through to recent iterative PET image reconstruction algorithms, and then review deep learning methods for PET data up to the latest innovations within three main categories. The first category involves post-processing methods for PET image denoising. The second category comprises direct image reconstruction methods that learn mappings from sinograms to the reconstructed i...
Source: Radiological Physics and Technology - February 6, 2024 Category: Physics Source Type: research

Directional vector visualization of scattered rays in mobile c-arm fluoroscopy
AbstractPrevious radiation protection-measure studies for medical staff who perform X-ray fluoroscopy have employed simulations to investigate the use of protective plates and their shielding effectiveness. Incorporating directional information enables users to gain a clearer understanding of how to position protective plates effectively. Therefore, in this study, we propose the visualization of the directional vectors of scattered rays. X-ray fluoroscopy was performed; the particle and heavy-ion transport code system was used in Monte Carlo simulations to reproduce the behavior of scattered rays in an X-ray room by reprod...
Source: Radiological Physics and Technology - February 5, 2024 Category: Physics Source Type: research

Selection of Radiological Physics and Technology Awards 2023
(Source: Radiological Physics and Technology)
Source: Radiological Physics and Technology - February 3, 2024 Category: Physics Source Type: research

Development of an open project rectangular collimator for use with intraoral dental X-ray unit
AbstractIn this work, an open beam-limiting device, consisting of a rectangular collimator to be coupled to an intraoral dental X-ray device, was made using recycled lead sheets as a radiation-absorbing element. The collimator was designed for 3D printing, and using Spektr 3.0 software, the number of lead sheets needed to absorb excess radiation was calculated. The rectangular collimator reduced the radiation dose to patients by 65% when using four layers of recycled lead sheets (saturating with a 70% reduction in radiation dose at the limit of eight or more sheets of lead). The rectangular collimator does not negatively i...
Source: Radiological Physics and Technology - January 24, 2024 Category: Physics Source Type: research

Investigation of ionization chamber perturbation factors using proton beam and Fano cavity test for the Monte Carlo simulation code PHITS
AbstractThe reference dose for clinical proton beam therapy is based on ionization chamber dosimetry. However, data on uncertainties in proton dosimetry are lacking, and multifaceted studies are required. Monte Carlo simulations are useful tools for calculating ionization chamber dosimetry in radiation fields and are sensitive to the transport algorithm parameters when particles are transported in a heterogeneous region. We aimed to evaluate the proton transport algorithm of the Particle and Heavy Ion Transport Code System (PHITS) using the Fano test. The response of the ionization chamber\({f}_{{\text{Q}}}\) and beam qual...
Source: Radiological Physics and Technology - January 23, 2024 Category: Physics Source Type: research

Assessment of dosimetric approaches in evaluating radiation exposure for interventional cardiologists in Sri Lanka
AbstractInterventional cardiologists face significant radiation exposure during interventional cardiology procedures. Therefore, this study focuses on assessing radiation exposure among interventional cardiologists during their procedures. Specifically, it aims to determine the effectiveness of both single and double dosimeter methods in estimating annual occupational radiation doses. This research holds pioneering significance as it represents the very first study undertaken in Sri Lanka. Thirteen interventional cardiologists performed 486 interventional cardiology procedures over three months in three different healthcar...
Source: Radiological Physics and Technology - January 19, 2024 Category: Physics Source Type: research

Validating computer applications for calculating spatial resolution and noise property in CT using simulated images with known properties
AbstractThe purpose of this study was to evaluate, using simulated images with known property values, how accurately some computer applications for calculating modulation transfer function (MTF), task transfer function (TTF), or noise power spectrum (NPS) in computed tomography (CT) based on widely known techniques produce their results. Specifically, they were three applications applicable to the wire method for MTF calculation, two applications corresponding to the circular edge (CE) and linear edge (LE) methods for TTF, and one application using a two-dimensional Fourier transform for NPS, which are collectively integra...
Source: Radiological Physics and Technology - January 10, 2024 Category: Physics Source Type: research

Possible mechanisms and simulation modeling of FLASH radiotherapy
AbstractFLASH radiotherapy (FLASH-RT) has great potential to improve patient outcomes. It delivers radiation doses at an ultra-high dose rate (UHDR:  ≥ 40 Gy/s) in a single instant or a few pulses. Much higher irradiation doses can be administered to tumors with FLASH-RT than with conventional dose rate (0.01−0.40 Gy/s) radiotherapy. UHDR irradiation can suppress toxicity in normal tissues while sustaining antitumor efficiency, which i s referred to as the FLASH effect. However, the mechanisms underlying the effects of the FLASH remain unclear. To clarify these mechanisms, the development of simulation models tha...
Source: Radiological Physics and Technology - January 6, 2024 Category: Physics Source Type: research

Verifying institutionally developed hybrid 3D-printed coaxial cylindrical phantom for patient-specific quality assurance in stereotactic body radiation therapy of hepatocellular carcinoma
This study examines the effectiveness of a novel hybrid 3D-printed hybrid coaxial cylindrical phantom for PSQA in the SB RT of HCC. The study compared three different point dose verification techniques for PSQA: a traditional solid water phantom, two dimensional detector array I’MatriXX, and a newly developed hybrid 3D-printed phantom. Thirty SBRT HCC liver cases were examined using these techniques, and point doses were measured and compared to planned doses using the perpendicular composite method with solid water and I’MatriXX phantoms. Unlike the other two methods, the point dose was compared in true composite geom...
Source: Radiological Physics and Technology - January 3, 2024 Category: Physics Source Type: research

Development of an individual display optimization system based on deep convolutional neural network transition learning for somatostatin receptor scintigraphy
This study developed a method to individually optimize the display of whole-body SRS images using a deep convolutional neural network (DCNN) reconstructed by transfer learning of a DCNN constructed using Gallium-67 (67Ga) images. The initial DCNN was constructed using U-Net to optimize the display of67Ga images (493 cases/986 images), and a DCNN with transposed weight coefficients was reconstructed for the optimization of whole-body SRS images (133 cases/266 images). A DCNN was constructed for each observer using reference display conditions estimated in advance. Furthermore, to eliminate information loss in the original i...
Source: Radiological Physics and Technology - January 2, 2024 Category: Physics Source Type: research

Efficient quality assurance for isocentric stability in stereotactic body radiation therapy using machine learning
This study aims to predict isocentric stability for stereotactic body radiation therapy (SBRT) treatments using machine learning (ML), covers the challenges of manual assessment and computational time for quality assurance (QA), and supports medical physicists to enhance accuracy. The isocentric parameters for collimator (C), gantry (G), and table (T) tests were conducted with the RUBY phantom during QA using TrueBeam linac for SBRT. This analysis combined statistical features from the IsoCheck EPID software. Five ML models, including logistic regression (LR), decision tree (DT), random forest (RF), naive Bayes (NB), and s...
Source: Radiological Physics and Technology - December 31, 2023 Category: Physics Source Type: research

Evaluation of deep learning reconstruction on diffusion-weighted imaging quality and apparent diffusion coefficient using an ice-water phantom
This study assessed the influence of deep learning reconstruction (DLR) on the quality of diffusion-weighted images (DWI) and apparent diffusion coefficient (ADC) using an ice-water phantom. An ice-water phantom with known diffusion properties (true ADC  = 1.1 × 10–3 mm2/s at 0  °C) was imaged at various b-values (0, 1000, 2000, and 4000 s/mm2) using a 3  T magnetic resonance imaging scanner with slice thicknesses of 1.5 and 3.0 mm. All DWIs were reconstructed with or without DLR. ADC maps were generated using combinations of b-values 0 and 1000, 0 and 2000, and 0 and 4000 s/mm2. Based on the quantitative ...
Source: Radiological Physics and Technology - December 28, 2023 Category: Physics Source Type: research

Half-value layer measurements using solid-state detectors and single-rotation technique with lead apertures in spiral computed tomography with and without a tin filter
AbstractSolid-state detectors (SSDs) may be used along with a lead collimator for half-value layer (HVL) measurement using computed tomography (CT) with or without a tin filter. We aimed to compare HVL measurements obtained using three SSDs (AGMS-DM+  , X2 R/F sensor, and Black Piranha) with those obtained using the single-rotation technique with lead apertures (SRTLA). HVL measurements were performed using spiral CT at tube voltages of 70–140 kV without a tin filter and 100–140 kV (Sn 100–140 kV) with a tin filter in increments of 10  kV. For SRTLA, a 0.6-cc ionization chamber was suspended at the isocenter to...
Source: Radiological Physics and Technology - December 21, 2023 Category: Physics Source Type: research