Effects of Real-Time Dosimetry on Staff Radiation Exposure in the Cardiac Catheterization Laboratory.

OBJECTIVES: Radiation protection is essential for staff of cardiac catheterization laboratories in order to prevent long-term radiation- associated injury and disease. Instant feedback about the actual received dose may help operators to optimize the use of existing shielding devices. Therefore, the current study was designed to investigate whether routine use of real-time dosimetry may be able to reduce staff radiation exposure. METHODS AND RESULTS: Over a period of 72 days, operators and assisting nurses were equipped with RaySafe i3 real-time dosimeters (Unfors RaySafe AB), but had no access to the dosimetry results during the first half of the study. This was followed by a second period that allowed operators to modify their behavior according to the dosimetry results. Compared with the first phase, the knowledge of real-time dosimetry results led to a uniform reduction in radiation exposure of all team members by approximately 60%, independent of the chosen vascular access. There were no significant changes in fluoroscopy time, dose-area product, or patient characteristics. CONCLUSIONS: Real-time dosimetry effectively reduced staff radiation exposure in the cardiac catheterization laboratory. This change was caused by optimized use of existing shielding equipment since no modifications of the general procedural approach or patient characteristics had occurred.

Correlative assessment of cerebral blood flow obtained with perfusion CT and positron emission tomography in symptomatic stenotic carotid disease.

Twelve patients with ICA stenosis underwent dynamic perfusion computed tomography (CT) and positron emission tomography (PET) studies at rest and after acetazolamide challenge. Cerebral blood flow (CBF) maps on perfusion CT resulted from a deconvolution of parenchymal time-concentration curves by an arterial input function (AIF) in the anterior cerebral artery as well as in both anterior choroidal arteries. CBF was measured by [(15)O]H(2)O PET using multilinear least-squares minimization procedure based on the one-compartment model. In corresponding transaxial PET scans, CBF values were extracted using standardized ROIs. The baseline perfusion CT-CBF values were lower in perfusion CT than in PET (P>0.05). CBF values obtained by perfusion CT were significantly correlated with those measured by PET before (P<0.05) and after (P<0.01) acetazolamide challenge. Nevertheless, the cerebrovascular reserve capacity was overestimated (P=0.05) using perfusion CT measurements. The AIF selection relative to the side of carotid stenosis did not significantly affect calculated perfusion CT-CBF values. In conclusion, the perfusion CT-CBF measurements correlate significantly with the PET-CBF measurements in chronic carotid stenotic disease and contribute useful information to the evaluation of the altered cerebral hemodynamics.