Jongwat Cheewakul

Background: Reliable quantitative computed tomography (CT) imaging requires rigorous quality control. Scan parameters such as tube voltage (kVp), tube current (mA), and slice thickness can affect CT number accuracy, image uniformity, and image noise. Objective: To investigate the effects of tube voltage, tube current, and slice thickness on CT number accuracy, image uniformity, and noise in comparison with the International Atomic Energy Agency (IAEA) standards. Materials and Methods: CT number uniformity and image noise were assessed using a water phantom, while CT number accuracy was evaluated using a TOS phantom containing six materials of different densities: air, water, Delrin, acrylic, nylon, and polypropylene. The linear relationship between CT numbers and material density was analyzed using regression analysis (R²), and the results were compared with IAEA tolerances. Results: No significant differences (p>0.05) were observed between reference and measured CT numbers across the tested materials. Increasing tube current did not significantly affect CT numbers or image uniformity, although higher tube current reduced image noise. CT number linearity remained strong across all tube current settings, with R² values consistently above 0.9. Image noise for all settings remained within the IAEA tolerance range. However, at 80 kVp, image uniformity exceeded the ±10 HU limit, whereas 100-135 kVp complied with the standard. Conclusion: CT number linearity and accuracy were highly stable across variations in tube current and slice thickness, whereas image uniformity was affected at low tube voltage. These findings emphasize the importance of selecting an appropriate kVp, particularly 120 kVp, to preserve image quality and maintain compliance with IAEA quality control standards. The results provide evidence-based support for optimizing CT imaging protocols.

Objective: To 1) compare the radiation dose received by patients undergoing hemodialysis vascular access angioplasty using Angiogram mode and Road-map mode, 2) evaluate patient radiation dose relative to the International Atomic Energy Agency (IAEA) trigger levels, and 3) identify technical factors influencing dose variation. Materials and Methods: This retrospective analytical study included 195 patients who underwent hemodialysis vascular access angioplasty at Songklanagarind Hospital between December 2019 and December 2021 (Road-map: 80 patients; Angiogram: 115 patients). Collected parameters included dose area product (DAP), reference point air kerma (Ka,r), kVp, mAs, fluoroscopy time, frame rate, and number of images. Data were analyzed using an independent t-test and a one-sample t-test. Results: Mean DAP and Ka,r in Road-map mode (0.92 Gy·cm² and 3.19 mGy) were significantly higher than Angiogram mode (0.55 Gy·cm² and 1.60 mGy) (p<0.001). Although Road-map mode utilized shorter fluoroscopy time, its fixed higher frame rate (15 fps vs. 2 fps) resulted in greater radiation exposure. Both techniques remained well below IAEA trigger levels. Conclusion: Angiogram mode offers an advantage in minimizing radiation dose, whereas Road-map mode may be preferred when rapid image guidance is required.

Background: Radiologic technology (RT) education faces challenges in bridging theory and practice due to limited clinical opportunities. While virtual reality (VR) enables safe and repeatable practice, a systematic instructional design framework is needed to develop scalable, procedure-focused modules. Objective: This study evaluates the Radiologic Technology Virtual Reality (RTVR) framework that integrates 360-degree video capture, instructional overlays, interactive assets, and an immersive content authoring platform to deliver a contrast-enhanced computed tomography (CECT) brain scan module. Methods: In this open-label, parallel-group, randomized controlled trial, 36 year-2 and year-3 RT students with no prior clinical training in diagnostic radiology at a university hospital in Thailand were randomly allocated (1:1) to a VR group or a conventional document-based instruction (control) group. The VR group completed the VR module, a grounded instructional design framework using 360-degree videos and a structured prebrief and debrief, for 20 minutes using a head-mounted display. The control group studied standard curriculum materials for the same duration. Blinding of participants was not possible. Outcome assessment was blinded. The primary outcome was declarative knowledge gain, assessed using a 20-item multiple-choice test before and after intervention. Secondary outcomes included technology acceptance, student satisfaction, and physiological responses during VR immersion. Results: All 36 randomized participants (VR: n=18, control: n=18) completed the study and were included in the analysis. Experts validated the module as suitable and highly appropriate. Students reported high technology acceptance and satisfaction. Both VR and conventional methods produced substantial gains in declarative knowledge. No statistically significant difference in knowledge gain was detected between groups (test × group: unstandardized regression coefficient β=.056, 95% CI −1.360 to 1.473, P =.94). Year-2 students, who had less prior clinical exposure, showed larger pretest to posttest knowledge gains compared to year-3 students. Physiological monitoring showed a reduction in heart rate across the session, while blood pressure remained stable. No adverse events or VR-related discomfort requiring discontinuation was observed. Conclusions: The RTVR framework, which uses a real 360-degree video of authentic clinical settings, offers a scalable approach to procedural VR content creation without requiring specialist technical skills, distinguishing it from prior VR studies in radiography. These findings support the RTVR framework as a feasible, evidence-informed supplement to RT curricula for knowledge-focused procedural teaching, with learning outcomes comparable to those of conventional instruction in this context.