Radiological Physics and Technology This is an RSS file. You can use it to subscribe to this data in your favourite RSS reader or to display this data on your own website or blog.

Nationwide survey on the current situation of quality control of diagnostic displays in Japan
AbstractThe Japan Association of Radiological Technologists (JART) and the Japan Medical Imaging and Radiological Systems Industries Association jointly conducted a nationwide survey to reveal the current situation of diagnostic displays in Japan using a questionnaire on the performance and quality control (QC) of diagnostic displays for mammography and common use. The questionnaire for radiological technologists (RTs) was distributed via email to 4519 medical facilities throughout Japan, where RTs affiliated with JART were employed; 613 (13.6%) facilities responded. Diagnostic displays with suitable maximal luminance (500...
Source: Radiological Physics and Technology - April 25, 2023 Category: Physics Source Type: research

Comparison of dosimetric parameters and robustness for rotational errors in fractionated stereotactic irradiation using automated noncoplanar volumetric modulated arc therapy for patients with brain metastases: single- versus multi-isocentric technique
AbstractTo compare the dosimetric parameters of automated noncoplanar volumetric modulated arc therapy plans using single-isocentric (SIC) and multi-isocentric (MIC) techniques for patients with two brain metastases (BMs) in stereotactic irradiation and to evaluate the robustness of rotational errors. The SIC and MIC plans were retrospectively generated (35  Gy/five fractions) for 58 patients. Subsequently, a receiver operating characteristic curve analysis between the tumor surface distance (TSD) andV25Gy was performed to determine the thresholds for the brain tissue. The SIC and MIC plans were recalculated based on the ...
Source: Radiological Physics and Technology - April 24, 2023 Category: Physics Source Type: research

Stopping-power ratio of body tissues with updated effective energies and elemental I values for treatment planning of proton therapy  and ion beam therapy with helium, carbon, oxygen, and neon ions
AbstractThe stopping-power ratio (SPR) of body tissues relative to water depends on the particle energy and mean excitation energy (I value) of the tissues. Effective energies to minimize the range error in proton therapy  and ion beam therapy with helium, carbon, oxygen, and neon ions and elementalI values have been updated in recent studies. We investigated the effects of these updates on SPR estimation for computed tomography-based treatment planning. The updates led to an increase of up to 0.5% in the SPRs of soft tissues, whereas they led to a decrease of up to 1.9% in the SPRs of bone tissues compared with the curre...
Source: Radiological Physics and Technology - April 23, 2023 Category: Physics Source Type: research

Helical tomotherapy and two types of volumetric modulated arc therapy: dosimetric and clinical comparison for several cancer sites
AbstractRadiotherapy accelerators have undergone continuous technological developments. We investigated the differences between Radixact ™ and VMAT treatment plans. Sixty patients were included in this study. Dosimetric comparison between the Radixact™ and VMAT plans was performed for six cancer sites: whole-brain, head and neck, lymphoma, lung, prostate, and rectum. The VMAT plans were generated with two Elekta linear accelerato rs (Synergy® and Versa HD™). The planning target volume (PTV) coverage, organs-at-risk dose constraints, and four dosimetric indexes were considered. The deliverability of the plans was as...
Source: Radiological Physics and Technology - April 21, 2023 Category: Physics Source Type: research

Long-term experience in quality assurance of on-rail computed tomography systems for image-guided radiotherapy using in-house multifunctional phantoms
This study reported the QA status of the system during the period 2014–2021. The absolute mean accuracy of couch rotation was 0.4 ± 0.28 mm, 0.44 ± 0.36 mm, and 0.37 ± 0.27 mm in th e SI, RL, and AP directions, respectively. Horizontal and remote movement accuracies of the treatment couch were also within 0.5 mm of the absolute mean value. A decrease in the accuracy of couch rotation was also observed due to aging deterioration of related parts caused by the frequent use of co uch rotation. The three-dimensional accuracy of on-rail CT systems derived mainly from treatment couches can be maintained with...
Source: Radiological Physics and Technology - April 20, 2023 Category: Physics Source Type: research

Usefulness of copper filters in digital chest radiography based on the relationship between effective detective quantum efficiency and deep learning-based segmentation accuracy of the tumor area
This study aimed to determine the optimal radiographic conditions for detecting lesions on digital chest radiographs using an indirect conversion flat-panel detector with a copper (Cu) filter. First, we calculated the effective detective quantum efficiency (DQE) by considering clinical conditions to evaluate the image quality. We then measured the segmentation accuracy using a U-net convolutional network to verify the effectiveness of the Cu filter. We obtained images of simulated lung tumors using 10-mm acrylic spheres positioned at the right lung apex and left middle lung of an adult chest phantom. The Dice coefficient w...
Source: Radiological Physics and Technology - April 12, 2023 Category: Physics Source Type: research

Altered resting-state functional connectivity of the brain in children with autism spectrum disorder
This study investigated the pattern of brain connection changes in autistic people compared to healthy people. This study aimed to analyze functional abnormalities within  the brain due to ASD, using resting-state functional magnetic resonance imaging (fMRI). Resting-state functional magnetic resonance images of 26 individuals with ASD and 26 healthy controls were obtained from the Autism Brain Imaging Data Exchange (ABIDE) database. The DPARSF (data processing assi stant for resting-state fMRI) toolbox was used for resting-state functional image processing, and features related to functional connections were extracted fr...
Source: Radiological Physics and Technology - April 11, 2023 Category: Physics Source Type: research

Modulation transfer function measurement of three-dimensional T1-weighted turbo spin echo sequence with low refocusing flip angles using single-plate method
This study aimed to demonstrate the usefulness of modulation transfer function (MTF) measurements using the single-plate method to evaluate changes in resolution properties that are dependent on three parameters: echo train length (ETL), low refocusing flip angle (RFA), and start-up echo in three-dimensional T1-weighted turbo spin echoes (TSE) with a low RFA and to optimize these parameters. Although the MTFs were slightly degraded with an RFA of 120 °, they were considerably degraded with an RFA of ≤ 90°. On the other hand, the MTF of low RFA was greatly improved by setting the start-up echo, allowing setting a lo...
Source: Radiological Physics and Technology - March 26, 2023 Category: Physics Source Type: research

Effect of acoustic noise reduction technology on image quality: a multivendor study
AbstractThe purpose of this study was to clarify the appropriate use of a combination of pulse sequences and acoustic noise reduction technology in general-purpose brain magnetic resonance imaging. Five pulse sequences commonly used in brain magnetic resonance imaging examinations —turbo spin-echo T2-weighted imaging, T1-weighted fluid-attenuated inversion recovery, T2-weighted fluid-attenuated inversion recovery, diffusion-weighted imaging, and magnetic resonance angiography—were performed on healthy participants at three vendors where acoustic noise reduction technology was available. The results showed that acoustic...
Source: Radiological Physics and Technology - March 25, 2023 Category: Physics Source Type: research

Feasibility of using counts-per-volume approach with a new SPECT phantom to optimize the relationship between administered dose and acquisition time
AbstractWe developed a phantom for single-photon emission computed tomography (SPECT), with the objective of assessing image quality to optimize administered dose and acquisition time. We investigated whether the concept of counts-per-volume (CPV), which is used as a predictor of visual image quality in positron emission tomography, can be used to estimate the acquisition time required for each SPECT image. QIRE phantoms for the head (QIRE-h) and torso (QIRE-t) were developed to measure four physical indicators of image quality in a single scan: uniformity, contrast of both hot and defective lesions with respect to the bac...
Source: Radiological Physics and Technology - March 23, 2023 Category: Physics Source Type: research

Sensitivity of a bone-equivalent polymer gel dosimeter for measuring the dose to bone during radiation therapy
In this study, we developed a bone-equivalent polymer gel dosimeter (BPGD) that can measure the dose absorbed by the bone and investigated its sensitivity. The BPGDs were prepared by adding 3.0  mol of calcium hydrogen phosphate dihydrate as a component of bone to an improved dose-sensitive polyacrylamide gelatin and tetrakis hydroxymethyl phosphonium chloride (iPAGAT). One day after preparation, the BPGDs were irradiated with a field size of 15 × 15 cm2 using a 10 MV X-ray beam to evaluate the dose sensitivity, dose-rate dependence, and dose-integration dependence. One day after dose exposure, the BPGDs were scanned...
Source: Radiological Physics and Technology - March 22, 2023 Category: Physics Source Type: research

Virtual clinical trial based on outcome modeling with iteratively redistributed extrapolation data
In this study, we developedExMixup, a novel training technique based on machine learning, using iteratively redistributed extrapolated data. Information obtained from 100 patients with prostate cancer and 385 patients with oropharyngeal cancer was used to predict the recurrence after radiotherapy. Model performance was evaluated by developing outcome prediction models based on three types of training methods: training with original data (baseline), interpolation data (Mixup), and interpolation  + extrapolation data (ExMixup). Two types of VCTs were conducted to predict the treatment response of patients with distinct c...
Source: Radiological Physics and Technology - March 22, 2023 Category: Physics Source Type: research