Abstract An anthropomorphic phantom was scanned with Siemens Somatom computed tomography scanners using tube current modulation (TCM). Thorax of the phantom was first scanned without the use of a contact shield, followed by a scan with a 0.5 mm lead equivalent out-of-plane shield placed in the localizer but 1 cm caudally outside the scanned volume. Scans were repeated using the scanner’s organ radiation dose reduction feature. Pitch values 0.35, 0.6, and 1.05 were used. With a pitch of 1.05, the effects of TCM varied between scanners from 4.35% to 356% when scanning toward the caudal end of the scanned volume, when shield was used outside the scanned volume. Also, with some scanners, the use of XCare increased the cumulative tube current.
Abstract Sentinel lymph node biopsy is critical for breast cancer staging and management. While 99mTc-Phytate is the established standard radiotracer, 99mTc-Antimony Trisulfide has limited clinical application due to radiopharmaceutical supply constraints. This proof-of-concept study evaluates both radiotracers’ diagnostic effectiveness and validates 99mTc-Antimony Trisulfide as a viable alternative. This institutional study included 39 breast cancer patients undergoing sentinel lymph node biopsy. Patients received either 99mTc-Phytate (n = 28; 71.8%) or 99mTc-Antimony Trisulfide (n = 10; 25.6%) via periareolar (n = 24) or peritumoral (n = 15) injection. Sentinel lymph node identification and gamma probe concordance were analyzed. Mean patient age was 53.5 ± 9.5 years. Invasive ductal carcinoma predominated (87%). 99mTc-Phytate achieved 100% detection (28 of 28 patients), while 99mTc-Antimony Trisulfide achieved 90.9% (10 of 11 patients). Intraoperative gamma probe concordance was 100% in all successfully visualized cases (38 of 38). Both radiotracers effectively identify sentinel lymph nodes with high diagnostic accuracy. While 99mTc-Phytate remains the preferred first-line agent, 99mTc-Antimony Trisulfide represents a validated alternative, particularly valuable in resource-limited settings or during radiopharmaceutical supply disruptions.
Abstract Consumer-grade electronic radon monitors (ERMs) are becoming increasingly popular, yet evidence of their performance remains largely based on short-term testing of a limited number of devices. This study evaluated nine models of consumer-grade ERMs over a 3-month exposure period in a radon chamber to assess accuracy, precision, stabilization, drift, and temporal behaviour. Absolute mean difference (AMD) improved over time, with all devices achieving <25% AMD after 1 month. Detector technology was the primary determinant of temporal performance. Ionization chamber-based devices stabilized within 24 h but exhibited a slight positive bias, whereas photodiode-based devices required several weeks to stabilize yet produced more accurate long-term averages. Time-series analyses indicated that photodiode-based devices exhibited signatures of internal data processing that suppressed short-term variability. Overall, the ERMs evaluated provided reliable integrated measurements over test periods consistent with long-term testing guidance. These findings support the development of performance standards, certification programs, and public guidance.
Abstract This 3-y retrospective study analyzed 180 paired dosimetry records from five interventional radiologists and five cardiologists, comparing whole-body Hp(10) with eye-lens Hp(3) and extremity Hp(0.07) doses. Moderate-to-strong linear correlations were observed (r = 0.86–0.91, R2 = 0.73–0.83), indicating that chest-level dosemeters may support the estimation of localized exposure. Coefficients of variation were ~30% for k1 and 27% for k2, reflecting heterogeneous exposure conditions. Variance-component analysis showed that inter-operator variability accounted for 20%–25% of total variance, versus 75%–80% residual within-operator variability, likely reflecting differences in workload, case mix, positioning, exposure geometry, shielding, and measurement uncertainty. The eye-lens conversion coefficient was higher in cardiologists (1.8) than in the non-neurointerventional radiology/neurointerventional radiology group (0.68), suggesting that operator-group-specific conversion coefficients may be more appropriate than a single universal coefficient. Empirically derived conversion coefficients provide a valuable complementary approach for the retrospective estimation of localized dose exposure when dedicated dosimetry is unavailable.
Abstract This study assessed indoor radon (222Rn) concentrations across 150 dwellings in Obuasi, Ghana, using CR-39 SSNTDs over a 180-day period. The influence of wall construction materials (concrete, sandcrete, clay, and wood), interior finishes (paint and paper plaster), and floor variations (mortar and tile) on radon levels were evaluated alongside soil (226Ra) activity and 222Rn exhalation rates. Indoor 222Rn varied from 15.1 to 64.9 Bq m−3 (AM: 87.9 ± 10.1 Bq/m3), with concrete dwellings recording the highest concentrations and wooden dwellings the lowest. Bedrooms exhibited the highest indoor radon concentrations, consistent with limited ventilation and typically longer occupancy periods. Paper-plastered walls and tiled floors were associated with lower radon levels compared to painted walls and mortar floors. Strong positive correlations were observed between soil 226Ra, 222Rn exhalation rate (r = 0.87), and indoor radon (r = 0.61), confirming geogenic sources as primary contributors to indoor radon variability. Annual effective doses ranged from 0.3 to 9.2 mSv/yr, with 13% of locations exceeding International Commission on Radiological Protection (ICRP) reference limits. These findings offer evidence-based guidance for safer construction practices and support the development of national radon reference levels in Ghana.
