Native myocardial T1 mapping using inversion recovery T1-weighted turbo field echo sequence
This study proposes the use of the inversion recoveryT1-weighted turbo field echo (IR-T1TFE) sequence for myocardialT1 mapping and compares the results obtained with those of the modified Look-Locker inversion recovery (MOLLI) method for accuracy, precision, and reproducibility. A phantom containing seven vials with differentT1 values was imaged, thereby comparing theT1 measurements between the inversion recovery spin-echo (IR-SE) technique, MOLLI, and the IR-T1TFE. The accuracy, precision, and reproducibility of theT1-mapping sequences were analyzed in a phantom study. Fifteen healthy subjects were recruited for the in vi...
Source: Radiological Physics and Technology - March 26, 2024 Category: Physics Source Type: research

Setup time analysis for stereotactic body radiotherapy in O-ring linear accelerator without rotational correction
This study analyse setup time (ST) and frequency of on-board imaging for stereotactic abdomen (liver, stomach), lung, and spine radiotherapy in the absence of automatic rotational correction. Total 53 stereotactic body radiotherapy (SBRT) patients, 28 of abdomen, 19 lung, and 6 spine treated for 230 sessions in O-ring gantry accelerator were evaluated for ST analysis. The mean setup time for all patients, abdomen, lung, and spine cases were 7.7  ± 7.4 min, 9.2 ± 9.2 min, 6.3 ± 4.1 min, and 5.5 ± 3.3 min, respectively. Median number CBCT was 2. 96% of cases had a CBCT between 1 and 3, and 9 (4%) hadâ...
Source: Radiological Physics and Technology - March 25, 2024 Category: Physics Source Type: research

Feasibility study of radioactivity estimation of 99mTc and 123I-labeled radiopharmaceuticals using shielded syringes
This study investigates the feasibility of estimating the radioactivity of radiopharmaceuticals using shielded syringes. The radioactivities of99mTc-MDP,99mTc-HMDP,99mTc-ECD,99mTc-MAG3, and123I-IMP were measured using a dose calibrator. Correlation coefficients and regression equations were obtained from the radioactivity in the shielded and unshielded syringes.99mTc-MDP was also measured for residual radioactivity after the administration. The correlation coefficients of99mTc-MDP,99mTc-HMDP,99mTc-ECD,99mTc-MAG3, and123I-IMP werers = 0.9998,rs = 0.9997,rs = 0.9999,rs = 0.9998, andrs = 0.9888, respectively. The re...
Source: Radiological Physics and Technology - March 22, 2024 Category: Physics Source Type: research

Commissioning and dosimetric verification of volumetric modulated arc therapy for multiple modalities using electronic portal imaging device-based 3D dosimetry system: a novel approach
AbstractThe purpose of this study was to validate an electronic portal imaging device (EPID) based 3-dimensional (3D) dosimetry system for the commissioning of volumetric modulated arc therapy (VMAT) delivery for flattening filter (FF) and flattening filter free (FFF) modalities based on test suites developed according to American Association of Physicists in Medicine Task Group 119 (AAPM TG 119) and pre-treatment patient specific quality assurance (PSQA).With ionisation chamber, multiple-point measurement in various planes becomes extremely difficult and time-consuming, necessitating repeated exposure of the plan. The ave...
Source: Radiological Physics and Technology - March 16, 2024 Category: Physics Source Type: research

Correction to: Deep learning-based PET image denoising and reconstruction: a review
(Source: Radiological Physics and Technology)
Source: Radiological Physics and Technology - March 16, 2024 Category: Physics Source Type: research

Commissioning and dosimetric verification of volumetric modulated arc therapy for multiple modalities using electronic portal imaging device-based 3D dosimetry system: a novel approach
AbstractThe purpose of this study was to validate an electronic portal imaging device (EPID) based 3-dimensional (3D) dosimetry system for the commissioning of volumetric modulated arc therapy (VMAT) delivery for flattening filter (FF) and flattening filter free (FFF) modalities based on test suites developed according to American Association of Physicists in Medicine Task Group 119 (AAPM TG 119) and pre-treatment patient specific quality assurance (PSQA).With ionisation chamber, multiple-point measurement in various planes becomes extremely difficult and time-consuming, necessitating repeated exposure of the plan. The ave...
Source: Radiological Physics and Technology - March 16, 2024 Category: Physics Source Type: research

Correction to: Deep learning-based PET image denoising and reconstruction: a review
(Source: Radiological Physics and Technology)
Source: Radiological Physics and Technology - March 16, 2024 Category: Physics Source Type: research

Long-term geometric quality assurance of radiation focal point and cone-beam computed tomography for Gamma Knife radiosurgery system
AbstractTo investigate the geometric accuracy of the radiation focal point (RFP) and cone-beam computed tomography (CBCT) over long-term periods for the ICON Leksell Gamma Knife radiosurgery system. This phantom study utilized the ICON quality assurance tool plus, and the phantom was manually set on the patient position system before the implementation of treatment for patients. The deviation of the RFP position from the unit center point (UCP) and the positions of the four ball bearings (BBs) in the CBCT from the reference position were automatically analyzed. During 544  days, a total of 269 analyses were performed on d...
Source: Radiological Physics and Technology - March 11, 2024 Category: Physics Source Type: research

Denoising parameter dependence of coronary artery depictability in compressed sensing magnetic resonance angiography
This study was conducted to clarify the acceleration factor (AF) and denoising factor (DF) dependence of CS-MRA image quality. Vascular phantoms and clinical images were acquired using three-dimensional CS-MRA on a clinical 1.5  T system. For the phantom measurements, we compared the full width at half maximum (FWHM), sharpness, and contrast ratio of the vascular profile curves for various AFs and DFs. In the clinical cases, the FWHM, sharpness, contrast ratio, signal-to-noise ratio, noise level values, and visual evaluat ion results were compared for various DFs. Phantom image analyses demonstrated that the respective me...
Source: Radiological Physics and Technology - March 9, 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 - March 1, 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 - March 1, 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 - March 1, 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 - March 1, 2024 Category: Physics Source Type: research