There is increasing use of three-dimensional rotational angiography (3DRA) during cardiac ablation procedures. As compared with 2D angiography, a large series of images are acquired, creating the potential for high radiation doses. The aim of the present study was to quantify patient-specific effective doses. In this study, we developed a computer model to accurately calculate organ doses and the effective dose incurred during 3DRA image acquisition. The computer model simulates the exposure geometry and uses the actual exposure parameters, including the variation in tube voltage and current that is realized through the automatic exposure control (AEC). We performed 3DRA dose calculations in 42 patients referred for ablation on the Siemens Axiom Artis DynaCT system (Erlangen, Germany). Organ doses and effective dose were calculated separately for all projections in the course of the C-arm rotation. The influence of patient body mass index (BMI), dose-area product (DAP), collimation and dose per frame (DPF) rate setting on the calculated doses was also analysed. The effective dose was found to be 5.5 +/- 1.4 mSv according to ICRP 60 and 6.6 +/- 1.8 mSv according to ICRP 103. Effective dose showed an inversely proportional relationship to BMI, while DAP was nearly BMI independent. No simple conversion coefficient between DAP and effective dose could be derived. DPF reduction did not result in a proportional effective dose decrease. These paradoxical findings were explained by the settings of the AEC and the limitations of the x-ray tube. Collimation reduced the effective dose by more than 20%. Three-dimensional rotational angiography is associated with a definite but acceptable radiation dose that can be calculated for all patients separately. Their BMI is a predictor of the effective dose. The dose reduction achieved with collimation suggests that its use is imperative during the 3DRA procedure.

Flat-panel X-ray detectors for fluoroscopy represent a modern imaging equipment that is being implemented in paediatric cardiac catheterisation laboratories. Infants and children represent a group of patients with a high radiosensitivity. A survey of 273 (126 diagnostic and 147 therapeutic) paediatric catheterisations was performed to investigate the radiation doses delivered by the new X-ray system. Statistical parameters (75th, 50th and 25th percentiles) of dose-area product (DAP) and fluoroscopy time are reported for patients divided into six age groups: 0 -30 d, >1-12 m, >1-3, >3-5, >5 -10 and >10-15 y. For accurate risk estimation, effective dose (E) has been determined for all patients using the PCXMC software. For diagnostic procedures, the third quartile of E ranges from 11.3 mSv for newborns to 7 mSv for children of 10-15 y. Therapeutic procedures are more complex than diagnostic. Consequently, the third quartile of E is 22.6 mSv (0-30 d), 18.6 (>1 -12 m), 13.3 (>1-3 y), 21.5 (>3 -5 y), 17.8 (>5-10 y) and 34.1 mSv (>10-15 y). Dose conversion factors, which relate the DAP and E, have been estimated for each age group. The results of this study may serve as a first step in the optimisation process, in order to make full use of the dose reduction potential of flat-panel systems.

The purpose of this study was to determine diagnostic reference levels (DRLs) for common angiographic and interventional procedures in Belgium. Dose Area Product (DAP) measurements were performed on 21 systems, (13 angiography and 4 vascular surgery centres). Type of procedure, total DAP, patient weight and height were collected on a daily basis during 1 y. The 75th percentile of the distribution of DAP values was defined as DRL. Preliminary DRLs were calculated for the three most frequent procedures for the whole population, for a weight class of patients (65-80 kg) and normalised to the standard size patient. Among them, the DRL for angiography of the lower limbs (30% of the procedures) from the whole population was 74.6 and 63.2 Gycm2 for the size corrected. The mean DAP values of each room was then compared to these DRLs.

Lung disease represents one of the most life-threatening conditions in prematurely born children. In the evaluation of the neonatal chest, the primary and most important diagnostic study is therefore the chest radiograph. Since prematurely born children are very sensitive to radiation, those radiographs may lead to a significant radiation detriment. Hence, knowledge of the patient dose is necessary to justify the exposures. A study to assess the patient doses was started at the neonatal intensive care unit (NICU) of the University Hospital in Leuven. Between September 2004 and September 2005, prematurely born babies underwent on average 10 X-ray examinations in the NICU. In this sample, the maximum was 78 X-ray examinations. For chest radiographs, the median entrance skin dose was 34 microGy and the median dose area product was 7.1 mGy.cm(2). By means of conversion coefficients, the measured values were converted to organ doses. Organ doses were calculated for three different weight classes: extremely low birth weight infants (<1000 g), low birth weight infants (1000-2500 g) and normal birth weight infants (>2500 g). The doses to the lungs for a single chest radiograph for infants with extremely low birth weights, low birth weights and normal birth weights were 24, 25 and 32 microGy, respectively.