Appropriate administered-activity verification and consistent explanations for patients and guardians are essential in pediatric nuclear medicine. We developed an offline HTML application integrating Japanese guideline-based activity calculation, reference effective-dose display, patient explanation-sheet generation, and facility-level master-data customization. Ten radiological technologists completed 10 simulated cases using conventional and application methods. Agreement within ± 3
To evaluate the utility of a pruning method in refining tractography and to examine the Arcuate Fasciculus (AF) morphometry and diffusion metrics in right-handed adults. Thirty-two healthy, right-handed adults underwent DTI on a 1.5T MRI system. Q-space diffeomorphic reconstruction was performed on a single-shell DTI dataset, and the AF was automatically tracked. Topology-Informed Pruning (TIP) was applied to reduce false-positive streamlines across varying numbers of iterations. Morphometry and diffusion metrics of the bilateral AF were extracted. The associations between these metrics and the number of iterations were evaluated using correlation analysis. The protocol-specific TIP threshold was identified as the knee point using the Kneedle algorithm. Differences in the morphometry and diffusion metrics of the selection AF tractometry by sex and hemisphere were also examined. A pFDR < 0.05 was considered statistically significant. TIP-based pruning was associated with improved tract delineation through the reduction of spurious streamlines. The number of pruning iterations affected the AF’s morphometry and diffusion metrics. The selected TIP threshold was 8, and TIPs greater than 8 yielded stable values with minimal variability. Significant differences between hemispheres were observed in diffusion metrics except quantitative anisotropy (QA). For morphometry metrics, significant differences were identified in the number of tracts, span, and curl (pFDR < 0.05). No significant sex-related differences were found after FDR correction. Pruning iterations affect the visualization of AF in the protocol-specific population of right-handed adults. The number of pruning iterations selected should be carefully determined with full awareness and consideration.
In this retrospective observer study, nine Japanese radiological technologists each performed fully manual offline cone-beam CT registration for 29 cases (261 registrations), blinded to the clinical reference positions adopted by radiation oncologists. Agreement was assessed by three-dimensional deviation; observer-level standard deviation across cases represented between-case variability. Associations with radiotherapy and overall professional experience were explored using Spearman correlations with exact permutation tests and leave-one-observer-out analyses. Mean deviation was 1.41 ± 1.16 mm (median, 1.06 mm); 74.7
Echocardiographers (ECs) often stand close to the patient during structural heart interventions (SHIs) and may receive higher occupational radiation exposure than interventional cardiologists (ICs). Previous studies have relied on cumulative dose measurements, leaving the per-event determinants of occupational radiation dose poorly characterized. We quantified the per-event personal dose equivalent rate at a 10-mm depth [Hp(10)] for ECs and ICs during SHIs and identified its determinants. We prospectively analyzed 37 SHI cases (20 mitral transcatheter edge-to-edge repair procedures and 17 left atrial appendage occlusion procedures) at a single center between March 2024 and March 2025. The EC and IC each wore two semiconductor dosimeters (on the front and side of the neck) sampling at 1 Hz, and the higher reading was used for analysis. Per-event Hp(10) rates were calculated by integrating dosimetry data, radiation dose structured report information, and video-based shielding labels. A prespecified linear mixed-effects model with a case-level random intercept assessed X-ray output, beam geometry, operator shielding, and C-arm angulation as candidate determinants for each operator. Among 3,222 exposure events, the EC-to-IC ratio of the Hp(10) rate was 2.3 during fluoroscopy and 3.8 during cine acquisition (both p < 0.001). In the multivariable model, log10(Ka,r rate), protocol, C-arm angle, source-to-detector distance, field of view, and operator shielding were independent predictors of the Hp(10) rate for both operators. The EC experienced substantially higher per-event Hp(10) rates than the IC, particularly during cine acquisition. Operator-specific shielding strategies and per-event optimization of X-ray output are warranted.
In helical tomotherapy (HT), the beam intensity is modulated by controlling the leaf open time (LOT) of a binary multileaf collimator (MLC), represented as sinograms. Comparing planned and recorded sinograms enables the evaluation of MLC delivery errors. This study proposes a novel sinogram difference metric—the time difference rate (TDR)— and evaluates its association with treatment planning parameters and the Patient-specific quality assurance gamma passing rate (GPR). Treatment plans of 153 patients with head and neck cancer who underwent IMRT with HT were retrospectively analyzed. Planned and recorded sinograms were compared to calculate relative and absolute TDRs, defined as the percentage of active sinogram elements exceeding predefined LOT difference thresholds. Relative TDR thresholds were 2 TDR_3% and TDR_5% showed weak but significant correlations with GPRs, with Spearman’s rank correlation coefficients ranging from − 0.241 to − 0.175. Among the absolute metrics, TDR_10ms , TDR_15ms , and TDR_20ms showed weak but significant negative correlations with GPR 3 TDR_3% and TDR_5% may complement conventional PSQA by directly evaluating MLC delivery accuracy from recorded sinograms.
