METHODS: A phantom study was performed to investigate the correlation of (1)H MRS-visible lipids with the signal loss ratio (SLR) obtained using IOP imaging. A cross-sectional study approved by the institutional review board was carried out in 22 patients with different glioma grades. The patients underwent scanning using IOP imaging and single-voxel spectroscopy (SVS) using 3T MRI. The brain spectra acquisitions from solid and cystic components were obtained and correlated with the SLR for different grades.
RESULTS: The phantom study showed a positive linear correlation between lipid quantification at 0.9 parts per million (ppm) and 1.3 ppm with SLR (r = 0.79-0.99, p
MATERIALS AND METHODS: Prospectively ECG-triggered CCTA was performed using five commercially available CT scanners: 64-detector-row single source CT (SSCT), 2 × 32-detector-row-dual source CT (DSCT), 2 × 64-detector-row DSCT and 320-detector-row SSCT scanners. Absorbed doses were measured in 34 organs using pre-calibrated optically stimulated luminescence dosimeters (OSLDs) placed inside a standard female adult anthropomorphic phantom. HE was calculated from the measured organ doses and compared to the HE derived from the air kerma-length product (PKL) using the conversion coefficient of 0.014 mSv∙mGy-1∙cm-1 for the chest region.
RESULTS: Both breasts and lungs received the highest radiation dose during CCTA examination. The highest HE was received from 2 × 32-detector-row DSCT scanner (6.06 ± 0.72 mSv), followed by 64-detector-row SSCT (5.60 ± 0.68 and 5.02 ± 0.73 mSv), 2 × 64-detector-row DSCT (1.88 ± 0.25 mSv) and 320-detector-row SSCT (1.34 ± 0.48 mSv) scanners. HE calculated from the measured organ doses were about 38 to 53% higher than the HE derived from the PKL-to-HE conversion factor.
CONCLUSION: The radiation doses received from a prospectively ECG-triggered CCTA are relatively small and are depending on the scanner technology and imaging protocols. HE as low as 1.34 and 1.88 mSv can be achieved in prospectively ECG-triggered CCTA using 320-detector-row SSCT and 2 × 64-detector-row DSCT scanners.
METHODS: We scrutinized the routine radiological exposure parameters during 58 clinical neuro-interventional procedures such as, exposure direction, magnification, frame rate, and distance between image receptor to patient's body and evaluate their effects on patient's dose using an anthropomorphic phantom. Radiation dose received by the occipital region, ears and eyes of the phantom were measured using MOSkin detectors.
RESULTS: DSA imaging technique is a major contributor to patient's dose (80.9%) even though they are used sparingly (5.3% of total frame number). The occipital region of the brain received high dose largely from the frontal tube constantly placed under couch (73.7% of the total KAP). When rotating the frontal tube away from under the couch, the radiation dose to the occipital reduced by 40%. The use of magnification modes could increase radiation dose by 94%. Changing the image receptor to the phantom surface distance from 10 to 40cm doubled the radiation dose received by the patient's skin at the occipital region.
CONCLUSION: Our findings provided important insights into the contribution of selected fluoroscopic exposure parameters and their impact on patient's dose during neuro-interventional radiology procedures. This study showed that the DSA imaging technique contributed to the highest patient's dose and judicial use of exposure parameters might assist interventional radiologists in effective skin and eye lens dose reduction for patients undergoing neuro-interventional procedures.
HIGHLIGHTS: • Intrabeam x-ray source and spherical applicators were simulated and skin dose was calculated. • Skin dose for constant skin to applicator distance strongly depends on applicator size. • Use of larger applicators generally results in higher skin dose. • The recommended 0.5-1 cm skin to applicator distance does not guarantee skin safety.