Radiological Physics and Technology最新文献

Anatomical changes during Head and Neck Cancer (HNC) radiotherapy can compromise target volume dose coverage and Organs at Risk (OARs) sparing. This study evaluated the volumetric, dosimetric, clinical, and cost-effectiveness impacts of Adaptive Radiotherapy (ART) in HNC patients treated with Three-Dimensional Conformal Radiotherapy (3D-CRT) and Con-Current Chemo-Radiotherapy (CCRT) in resource-limited settings. Fifteen patients with advanced HNC were treated using 3D-CRT with CCRT to a total dose of 70 Gray (Gy) in 35 fractions. A repeat Computed Tomography (re-CT) simulation was performed at 44 Gy due to anatomical changes such as weight loss and tumor shrinkage during the treatment. Adaptive plans were generated using the re-CT images. Pre- and re-CT simulation images were fused, and Planning Target Volumes (PTVs) from the initial and adaptive plans were compared to evaluate the volumetric changes. Adaptive plans were then compared with the initial plans using Dose-Volume Histograms (DVHs), and dosimetric variations in Gross Tumor Volume (GTV), Clinical Target Volume (CTV), and PTV were evaluated. Target coverage deterioration observed with 3D-CRT was mitigated by ART, resulting in improved coverage for both high- and low-dose target volumes compared with the accumulated planned dose. The mean body weight ratio was 0.88 (12% weight loss), and the mean PTV volume ratio up to 44 Gy was 0.76 (24% reduction). Adaptive plans reduced the relative mean dose to the spinal cord 3.2%, brainstem 1.4%, ipsilateral parotid 4.10%, contralateral parotid 2.75%, esophagus 7.40%, mandible 3.60%, and oral cavity 5.60%, while dose coverage of GTV, CTV, and PTV improved by 3.50%, 3.06%, and 2.67%, respectively. ART combined with 3D-CRT and CCRT enhances target coverage while reducing doses to OARs. Re-CT-based adaptive planning at approximately 44 Gy appears to be a feasible and cost-effective strategy for maintaining dosimetric accuracy and adapting to volumetric changes in resource-limited settings.

Contrast-enhanced computed tomography (CECT) of the abdomen and pelvis is widely used for diagnostic imaging but contributes substantially to cumulative medical radiation exposure. Low tube voltage (kVp) imaging has gained attention as a practical strategy for radiation dose optimization while maintaining diagnostic image quality.The study aimed to map the current evidence on low-kVp techniques for radiation dose reduction in adult abdominopelvic CECT and evaluate their effects on radiation dose and image quality. This scoping review was conducted in accordance with the Arksey and O'Malley framework and PRISMA-ScR guidelines. A systematic search of Scopus, PubMed, Web of Science, Cochrane Library, and CINAHL identified studies published between 2000 and 2025 that reported low-kVp dose optimization strategies in adult patients. Data were extracted on scanner characteristics, tube voltage settings, reconstruction techniques, and reported dose reductions. Thirteen studies (sample size: 30-907) patients were included. Tube voltage settings ranged from 80 to 120 kVp, with 80 kVp consistently achieving substantial dose reductions (11-86%), particularly when combined with hybrid, model-based, or deep learning reconstruction algorithms that mitigated image noise and preserved diagnostic confidence. Automatic tube voltage selection and patient size-adapted protocols further supported individualized dose optimization. However, considerable heterogeneity in imaging protocols, reconstruction methods, and dose metrics limited comparability across studies. Low-kVp imaging is an effective approach for reducing radiation dose in contrast-enhanced abdominopelvic CT without compromising diagnostic adequacy. Standardized reporting and large prospective multicenter studies are needed to establish optimal protocols and support broader clinical implementation.

We evaluated whether, compared with conventional deep learning reconstruction (DLR) and zero-filling interpolation (ZIP), super-resolution DLR (SR-DLR) enhances the visualization of vestibular schwannomas and cranial nerves in three-dimensional constructive interference in steady state (3D-CISS) magnetic resonance (MR) imaging. This retrospective study analyzed 39 patients with vestibular schwannomas who underwent 3T MR imaging with 3D-CISS. Axial images were reconstructed using SR-DLR, DLR, and ZIP. Three readers independently evaluated tumor depiction, depiction of facial and vestibulocochlear nerves, sharpness, noise, artifacts, and diagnostic acceptability. Quantitative indicators included edge rise distance (ERD) and edge rise slope (ERS) measured along a linear region of interest (ROI) drawn perpendicularly across the tumor-cistern cerebrospinal fluid (CSF) boundary, and signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and contrast ratio (CR) calculated from circular ROIs (3-5 mm) placed in the tumor and prepontine CSF. SR-DLR significantly improved visualization of vestibular schwannoma and facial and vestibulocochlear nerves compared with ZIP (p < 0.001). Nerve depiction ratings varied between readers when comparing SR-DLR and DLR. SR-DLR yielded significantly better sharpness, lower ERD and higher ERS than both DLR and ZIP (p < 0.001). Artifacts showed no significant differences. No clear deterioration in noise was noted. Objectively, SR-DLR showed significantly higher CR than DLR (p = 0.023) and ZIP (p < 0.001). SNR and CNR were significantly higher with SR-DLR than ZIP, but comparable to DLR. SR-DLR improves sharpness and lesion conspicuity on 3D-CISS imaging without a clear increase in artifacts or noise compared with ZIP.

Accurate segmentation of Crohn's disease (CD) lesions from computed tomography enterography (CTE) cross-sectional images is crucial for diagnosing CD patients and may assist in developing a personalized treatment plan. However, to the best of our knowledge, studies on automatic CD lesion segmentation remain limited. This paper proposes a novel model (named CDSegNet) based on the U-Net to improve the segmentation of CD lesions. The model integrates a residual dilated and standard convolution feature extract (RDCFE) module to enhance fine-grained and global feature extraction while preserving information flow. Furthermore, a residual attention feature extraction (RAFE) module is introduced in the decoder to refine features and sharpen ambiguous lesion boundaries. In addition, a multi-scale convolution module is designed to aggregate features from different receptive fields to improve robustness across varying lesion sizes. Finally, Intersection over Union (IoU), Recall, Dice Similarity Coefficient (DSC), and Hausdorff distance (HD) are employed to quantitatively assess the model performance. The Recall, IoU, HD, and DSC of the CDSegNet are 0.867, 0.820, 23.28, and 0.895, respectively. Compared to the baseline model U-Net on our dataset, the IoU, HD, and DSC improve by 11.6%, 3.21, and 10.4%, respectively. Experiment results demonstrate that CDSegNet exhibits competitive performance under the current experimental setting, with particular strengths in segmenting small and medium lesions and achieving stable segmentation across all test images. However, further validation is needed prior to clinical application.

This retrospective study evaluates the dosimetric performance of coplanar versus non-coplanar volumetric modulated arc therapy (VMAT) for hippocampal avoidance whole-brain radiotherapy (HA-WBRT) using the Monaco treatment planning system. Ten patients were replanned using four techniques: three coplanar configurations with two, three, and four arcs, and one plan with both coplanar and non-coplanar arcs. A prescription of 30 Gy in 10 fractions was delivered to the planning target volume (PTV). Increasing the number of coplanar arcs improved target coverage and homogeneity, with the four-arc coplanar plan achieving PTV coverage, conformity, and homogeneity comparable to the non-coplanar approach. All techniques met protocol constraints for hippocampal and organ-at-risk doses, although non-coplanar VMAT produced the lowest absolute hippocampal doses. Non-coplanar plans required higher monitor units and longer treatment times. Four-arc coplanar VMAT demonstrated comparable dosimetric performance with improved delivery efficiency, supporting its use as a practical alternative in settings where non-coplanar delivery is limited.

Impatience is closely associated with stress, anxiety, and tension, all of which can adversely affect task performance and decision-making. Previous research analyzing incident reports from radiological technologists (RTs) has shown that impatience contributes to incidents regardless of years of experience. Based on these findings, this study aimed to evaluate the effectiveness of a group-work intervention designed to regulate feelings of impatience. A group-work session titled "Coping with Impatience and Its Effects" was conducted with 16 RTs at Kyoto University Hospital (mean experience: 5.2 years, SD: 7.2 years). A 9-item questionnaire, using a 4-point scale to assess common clinical scenarios, was administered at four time points: pre-intervention, immediately after, 1 month after, and 6 months after the intervention. Changes in scores were analyzed using the Wilcoxon signed-rank test. Regarding the degree of impatience, scores for impatience caused by others (e.g., doctors and nurses) decreased significantly immediately after (Z = 2.38, p < 0.05, r = 0.59), at 1 month (Z = 2.12, p < 0.05, r = 0.53), and at 6 months (Z = 3.01, p < 0.01, r = 0.75). Impatience due to time constraints decreased significantly only immediately after the intervention (Z = 2.76, p < 0.01, r = 0.69). Impatience related to patients showed significant reductions at 1 month (Z = 2.62, p < 0.01, r = 0.66) and at 6 months (Z = 2.35, p < 0.05, r = 0.59). Regarding the impact on performance, impatience caused by others decreased significantly immediately post-intervention (Z = 2.31, p < 0.05, r = 0.58) and at 1 month (Z = 2.13, p < 0.05, r = 0.53). Time-related impact decreased significantly at all post-intervention time points (immediately after: Z = 2.97, p < 0.01, r = 0.74; 1 month: Z = 2.12, p < 0.05, r = 0.53; 6 months: Z = 2.13, p < 0.05, r = 0.53). No significant changes were observed in the impact of patient-related impatience. All significant effects demonstrated large effect sizes (r) according to Cohen's criteria. A group-work intervention focused on the emotional regulation of impatience may be effective in reducing both impatience and its impact on the duties of RTs. These findings suggest that such interventions could contribute to improved patient safety and enhanced professional well-being.

To evaluate the effects of photon beam energy on region-specific scalp dose and target coverage in whole-brain radiotherapy (WBRT), with additional assessment of field configuration. This study was conducted as a benchmark dosimetric investigation using an anthropomorphic head phantom. WBRT plans were generated with a field-in-field technique and lateral opposed fields. Photon beam energies of 4, 6, 8, 10, and 15 MV were assessed under two field configurations: an open-field plan and a close-field plan without air space. The scalp was segmented into four anatomical regions. Dosimetric evaluation included planning target volume coverage, homogeneity index, scalp D_2cc, and normal tissue complication probability (NTCP) for permanent alopecia based on generalized equivalent uniform dose. Lens and cochlear doses were also analyzed. PTV coverage and dose homogeneity were comparable across beam energies. In all scalp regions, dose decreased with increasing photon beam energy, with the strongest dependence in the top and back regions. The lowest scalp NTCP was observed at 15 MV, although 8-10 MV yielded comparable reductions. The close-field configuration consistently reduced scalp dose relative to the open-field approach, with a maximum NTCP reduction of approximately 17%. Lens dose was lower with the close-field approach, whereas cochlear dose decreased with decreasing photon beam energy. Photon beam energy selection in WBRT has a clear region-specific impact on scalp dose. Energies of 8-10 MV, particularly with a close-field approach, may provide a practical balance between scalp sparing, OAR protection, and clinical feasibility.

To compare surface dose at the mammary gland level between 70- and 120-kVp non-contrast neonatal chest computed tomography (CT) under matched volume CT dose index (CTDIvol) conditions, a neonatal anthropomorphic phantom was scanned using a 256-row CT scanner. Real-time dosimeters were placed bilaterally on the anterior chest wall at the mammary gland level and on the posterior chest wall at the same axial level. For the 70-kVp protocol, the noise index was adjusted to match the console-displayed CTDIvol of the 120-kVp protocol. Each protocol was repeated 15 times, and image noise was measured on axial images. Anterior surface dose was significantly higher with 70 kVp than with 120 kVp (median [IQR], 5.67 [5.17-5.86] vs. 5.29 [4.84-5.43] mGy; p < 0.01). Posterior surface dose and image noise did not differ significantly. Under matched CTDIvol conditions, 70-kVp neonatal chest CT increased anterior mammary surface dose relative to 120-kVp CT in this phantom.

This study aimed to evaluate the image quality and delineation of the cystic artery and related abdominal vessels using Super-Resolution Deep Learning Reconstruction (SR-DLR) on contrast-enhanced computed tomography (CT), compared with standard Deep Learning Reconstruction (DLR). This retrospective study included 60 patients who underwent contrast-enhanced abdominal CT with an arterial phase between April and June 2025. Images were reconstructed using both SR-DLR and DLR algorithms. Quantitative evaluation included CT attenuation values, image noise, contrast-to-noise ratio (CNR), full width at half maximum (FWHM), and edge rise distance and edge rise slope (ERD/ERS) for the superior mesenteric artery (SMA) and proper hepatic artery (PHA). Three radiologists independently performed qualitative assessments of cystic artery, PHA, SMA, and cystic duct delineation, as well as image noise, sharpness, and artifacts. SR-DLR showed significantly lower image noise and higher CT attenuation values and CNR than DLR (p < 0.001). SR-DLR yielded higher ERS and lower ERD for the PHA and SMA compared to DLR (p ≤ 0.006). Qualitative analysis demonstrated that all three readers rated cystic artery delineation as significantly better with SR-DLR than with DLR (p ≤ 0.018). SR-DLR also achieved higher scores for image sharpness and diagnostic acceptability (p ≤ 0.001). SR-DLR significantly improves the delineation and image quality of the cystic artery and adjacent vascular anatomy compared with DLR. While no significant improvement in cystic artery detection was observed, the enhanced image quality may better support clinical confidence in preoperative planning for cholecystectomy and interventional radiology procedures.