Fluoroscopy Dose Area Product Research Articles

Identification of less-irradiating tube angulations in invasive cardiology

We sought to identify tube angulations in invasive cardiology, which promise minimal radiation exposure to patients and operators. Radiation exposure in invasive cardiology is high. We mapped the fluoroscopic dose-area product per second (DAP/s), applied to an anthropomorphic Alderson-Rando phantom and, in absence of radiation protection devices, the mean personal dose in the operator's position in 10 degrees steps from the 100 degrees right anterior oblique (RAO) to the 100 degrees left anterior oblique (LAO) projection, as well as for all geometrically feasible craniocaudal tube angulations. For our specific setting conditions RAO 20 degrees /0 degrees tube angulation generated the lowest DAP/s and operator's personal dose. The mean patient DAP/s and operator personal dose for all postero-anterior (PA) projections, cranialized and caudalized together, rose significantly: 3.7 and 10.6 times the PA 0 degrees baseline values toward LAO 100 degrees and 3.7 and 2.4 times toward RAO 100 degrees , respectively. Patient and operator values for all PA projections, angulated to the right and left, increased approximately 2.5 times toward 30 degrees craniocaudal angulations. Caudal PA 0 degrees /30 degrees - angulation instead of caudal LAO 60 degrees /20 degrees - angulation for the left coronary main stem and cranial PA 0 degrees /30 degrees + view in place of cranial LAO 60 degrees /20 degrees + view for the left anterior descending coronary artery bifurcation enable 2.6-fold dose reductions to the patient and eight- and five-fold dose reductions to the operator, respectively. The PA views and RAO views >or=40 degrees , heretofore unconventional in clinical routine, should be favored over steep LAO projections >or=40 degrees whenever possible. Tube angulations that are radiation intensive to the patient exponentially increase the operator's radiation risk.

Dose-Area Product Measurements During Angiographic X Ray Procedures

Radiation exposure during angiography is relatively high compared with other types of radiological procedures. In order to estimate the integral radiation dose absorbed by the patient, the applied dose-area product (DAP) is the most appropriate measurement. The purpose of this study was a systematic recording of measured fluoroscopic DAP, spot DAP, and total DAP as well as detailed examination data acquired at our Department of Diagnostic Radiology to obtain a profile of the radiation exposure in everyday angiographic routine. The data of 86 angiographic X ray procedures were acquired during four weeks. Of these, 74 were among the five most frequent examination types: femoral angiography, iliacofemoral angiography, percutaneous transluminal angioplasty (PTA), carotid angiography and renal angiography. The measured DAP varied considerably, depending on the type of procedure and even among procedures of the same type. Angiography of the lower extremities produced the lowest values (16 Gy.cm2); 177 Gy.cm2 during renal angiography was the highest recorded median DAP.

The secondary radiation grid; its effect on fluoroscopic dose-area product during barium enema examinations.

The secondary radiation grid is placed between the patient and the image intensifying screen, during fluoroscopy, to attenuate the incident forward scattered radiation. This reduction in scatter improves the radiographic contrast and hence image quality. However, this improved quality is achieved at the expense of greater radiation exposure to the patient, as this higher exposure is required to produce satisfactory image density. Patients scheduled to have a barium enema were randomly allocated into two groups. One group had the procedure performed with the grid in situ throughout the procedure. The second group was examined with the grid removed for fluoroscopy but returned for image acquisition. The fluoroscopic dose-area product (DAP) was recorded for both groups using a dose-area product meter. The DAP was not recorded for spot film acquisition. The results suggest that there is approximately a 50% reduction in DAP to the second group. We can be 95% certain that, on average, the ratio of doses in patients without the grid in situ to those screened with the grid is between 0.40 and 0.58, with the best estimate being 0.48. Multiple regression methods to take account of the effects of weight, sex and time, revised this estimate as 0.57, with 95% confidence interval from 0.52 to 0.63. Sex, weight and exposure time accounted for 61% of variation in dose-area products, with time alone accounting for 41%. Grid status accounted for another 22% of variation, which represents over a half of the remaining variation once sex, weight and exposure time have been allowed for. We therefore recommend that the routine use of an antiscatter grid during fluoroscopy should be abandoned. The use of a grid should be restricted to those patients (usually obese) when poor visualization is obtained in its absence.

Automatic system for measuring dose - area product (DAP) in ROI fluoroscopy

A computerized system for monitoring dose - area product (DAP) has been developed for region of interest (ROI) fluoroscopy in which patient exposure is reduced using an x-ray attenuating filter with an aperture. The system includes an IBM compatible computer which is connected through an IEEE-488 interface to an electrometer which measures the charge from a DAP ionization chamber. A digital input/output board connects the computer to the filter placement device to determine whether the filter is in or out of the beam, and to the x-ray generator to determine when the exposure is due to spot filming. The computer logs the DAP from conventional fluoroscopy, ROI fluoroscopy and spot filming separately, applying the appropriate calibration factor for each. Measured DAPs, fluoroscopic DAP rates and exposure times are displayed in real-time. The system has been installed in a GI fluoroscopic room so that the dose-reduction potential of ROI imaging can be evaluated.