Background-Because of the higher radiosensitivity of infants and children compared with adults, there is a need to evaluate the doses delivered to pediatric patients who undergo interventional cardiac procedures. However, knowledge of the effective dose in pediatric interventional cardiology is very limited. Methods and Results-For an accurate risk estimation, a patient-specific Monte Carlo simulation of the effective dose was set up in 60 patients with congenital heart disease who underwent diagnostic (nϭ28) or therapeutic (nϭ32) cardiac catheterization procedures. The dose-saving effect of using extra copper filtration in the x-ray beam was also investigated. For diagnostic cardiac catheterizations, a median effective dose of 4.6 mSv was found. Therapeutic procedures resulted in a higher median effective dose of 6.0 mSv because of the prolonged use of fluoroscopy. The overall effect of inserting extra copper filtration into the x-ray beam was a total effective dose reduction of 18% with no detrimental effect on image quality. An excellent correlation between the dose-area product and effective patient dose was found (rϭ0.95). Hence, dose-area product is suitable for online estimation of the effective dose with good accuracy. With all procedures included, the resulting median lifetime risk for stochastic effects was 0.08%. Conclusions-Because

ABSTRACT. For 318 patients in 8 different Belgian hospitals, the entire skin-dose distribution was mapped using a grid of 70 thermoluminescence dosemeters per patient, allowing an accurate determination of the maximum skin dose (MSD). Dosearea product (DAP) values, exposure parameters and geometry, together with procedure, patient and cardiologist characteristics, were also registered. Procedures were divided into two groups: diagnostic procedures (coronary angiography) and therapeutic procedures (dilatation, stent, combined procedures (e.g. coronary angiography + dilatation + stent)). The mean value of the MSD was 0.310 Gy for diagnostic and 0.699 Gy for therapeutic procedures. The most critical projection for receiving the MSD is the LAO90 (left anterior oblique) geometry. In 3% of cases, the MSD exceeded the 2 Gy dose threshold for deterministic effects. Action levels in terms of DAP values as the basis for a strategy for follow-up of patients for deterministic radiation skin effects were derived from measured MSD and cumulative DAP values. Two DAP action levels are proposed. A first DAP action level of 125 Gy cm 2 corresponding to the dose threshold of 2 Gy would imply an optional radiopathological follow-up depending on the cardiologist's decision. A second DAP action level of 250 Gy cm 2 corresponding to the 3 Gy skin dose would imply a systematic follow-up. Dose reference levels -71.3 Gy cm 2 for diagnostic and 106.0 Gy cm 2 for therapeutic procedures -were derived from the 75 percentile of the DAP distributions. As a conclusion, we propose that total DAP is registered in patient's record file, as it can serve to improve the follow-up of patients for radiation-induced skin injuries.

Highlights Longitudinal CBCT radiomics does not show added prognostic information for NSCLC. A CT-radiomics model could be validated in an external validation dataset. Dataset heterogeneity and small cohort sizes could cause poor validation performance.

In this paper, a large-scale multicentre patient dose study performed in eight Belgian interventional cardiology departments is presented. Effective dose (E) was calculated based on a detailed dose-area product (DAP)-registration during each procedure and by using conversion coefficients generated by the Monte Carlo-based computer program PCXMC. Conversion coefficients were found to be 0.177 mSv Gycm(-2) for systems that do not use any additional copper filtration in cineradiography and 0.207 mSv Gycm(-2) for systems that use additional copper filtration in cineradiography. Mean E values of 9.6 and 15.3 mSv for diagnostic and therapeutic procedures, respectively, were obtained. DAP distributions were investigated in order to derive dose reference levels: 71 and 106 Gycm2 for diagnostic and therapeutic procedures, respectively, are proposed. Significant differences were observed in DAP distributions taking into account whether additional copper filtration was used in the cineradiography mode. Apart from the skin, the organs most at risk are lungs and heart. The probability of fatal cancer for the studied population amounted to 1.1x10(-4) and 2.1x10(-4) for diagnostic and therapeutic procedures, respectively, for the age distribution of the patients considered in this multicentre study.

Effective dose (E), representing the risk of late radiation-induced effects, can be estimated by the use of conversion factors (CF), converting direct measurable quantities such as dose-area-product into E. Eight Belgian hospitals participated in the study with a total number of 318 procedures. E-values, calculated with PCXMC, were compared for the different hospitals for diagnostic and therapeutic procedures separately. E-values varied significantly depending on the hospital where the procedure was performed (P < 0.001), on filtration insertion (P < 0.001), on whether a centre is a training centre or not, the dose conscious action of the cardiologists and the complexity of the procedure (P < 0.001). Hospital-specific CF were calculated. An average CF of 0.185 mSv Gycm(-2) was obtained with a satisfactory correlation (r = 0.966, P < 0.001). The differences in CF between hospitals were due to, a large extent, the availability of additional filtration in cinegraphy mode (P < 0.001) and not to the differences in irradiation geometries in the clinical protocol of the interventional procedures.