Track, calculate and optimise eye lens doses of interventional cardiologists using mEyeDose and mEyeDose_X.

The European epidemiological study EURALOC aimed to establish a dose response relationship for low dose radiation induced eye lens opacities using interventional cardiologists as the study group. Within the EURALOC project, two dosimetry methodologies were developed serving as the basis for cumulative eye lens dose assessment. Besides being the cornerstone of the epidemiological part of the project, these dosimetry methodologies were also used to develop two calculation tools, 'mEyeDose' and 'mEyeDose_X' which enable to track, calculate, optimise and analyse eye lens doses in interventional cardiology. mEyeDose was developed as a Mobile Web App and serves as a readily accessible, highly didactic educational tool for interventional cardiologists whereas the user-friendly desktop application mEyeDose_X is designed for radiation protection professionals. Both tools are freely available and can be used for a wide range of purposes such as optimisation of working practices, calculation of cumulative eye lens doses or risk assessment prior to routine eye lens dose monitoring.

Does a flat panel detector reduce the patient radiation dose in interventional cardiology?

An internal audit has been performed to evaluate the patient radiation dose in the clinical use of X-ray cardiac flat panel detector (FPD) systems. Fluoroscopy and image acquisition (cine mode) programs are optimised for low-dose settings. The diagnostic and therapeutic interventional cardiac procedures are performed at 6 pulse s(-1) for fluoroscopy and 15 frames s(-1) for image acquisition. The FPD entrance dose is configured for 29 nGy pulse(-1) in the fluoroscopy mode and 0.10 microGy frame(-1) in the cine mode. From the data collected, the following local reference levels for coronary angiography and angioplasty have been obtained: kerma-area products 23 and 44 Gy cm(2), cumulative doses 376 and 776 mGy, fluoroscopy times 5 and 15.5 min and cine images 617 and 1163 images.

An investigation of flat panel equipment variables on image quality with a dedicated cardiac phantom.

Image quality (IQ) evaluation plays a key role in the process of optimization of new x-ray systems. Ideally, this process should be supported by real clinical images, but ethical issues and differences in anatomy and pathology of patients make it impossible. Phantom studies might overcome these issues. This paper presents the IQ evaluation of 30 cineangiographic films acquired with a cardiac flat panel system. The phantom used simulates the anatomy of the heart and allows the circulation of contrast agent boluses through coronary arteries. Variables investigated with influence on IQ and radiation dose are: tube potential, detector dose, added Copper filters, dynamic density optimization (DDO) and viewing angle. The IQ evaluation consisted of scoring 4 simulated calcified lesions located on different coronary artery segments in terms of degree of visualization. Eight cardiologists rated the lesions using a five-point scale ((1) lesion not visible to (5) very good visibility). Radiation doses associated to the angiograms are expressed in terms of incident air kerma (IAK) and effective dose that has been calculated with PCXMX software (STUK, Finland) from the exposure settings assuming a standard sized patient of 70 Kg. Mean IQ scores ranged from 1.68 to 4.88. The highest IQ scores were obtained for the angiograms acquired with tube potential 80 kVp, no added Cu filters, DDO 60%, RAO and LAO views and the highest entrance detector dose that has been used in the present study, namely 0.17 microGy/im. Radiation doses (IAK approximately 40 mGy and effective dose of 1 mSv) were estimated for angiograms acquired at 15 frames s(-1), detector field-of-view 20 cm, and a length of 5 s. The following parameters improved the IQ factor significantly: a change in tube potential from 96 to 80 kVp, detector dose from 0.10 microGy/im to 0.17 microGy/im, the absence of Copper filtration. DDO variable which is a post-processing parameter should be carefully evaluated because it alters the quality of the images independently of radiation exposure settings. The SAM anthropomorphic phantom has the advantage of visualization of stenotic lesions during the injection of a contrast agent and using an anatomical background. In the future, this phantom could potentially bridge the gap between physics tests and the clinical reality in the catheterization laboratory.

Patient dose in interventional radiology: a European survey.

Patient doses for a few common fluoroscopy-guided procedures in interventional radiology (IR) (excluding cardiology) were collected from a few radiological departments in 13 European countries. The major aim was to evaluate patient doses for the basis of the reference levels. In total, data for 20 procedures for about 1300 patients were collected. There were many-fold variations in the number of IR equipment and procedures per population, in the entrance dose rates, and in the patient dose data (total dose area product or DAP, fluoroscopy time and number of frames). There was no clear correlation between the total DAP and entrance dose rate, or between the total DAP and fluoroscopy time, indicating that a number of parameters affect the differences. Because of the limited number of patients, preliminary reference levels were proposed only for a few procedures. There is a need to improve the optimisation of IR procedures and their definitions and grouping, in order to account for their different complexities.

Radiation dose survey in a paediatric cardiac catheterisation laboratory equipped with flat-panel detectors.

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.

Radiation dose levels during interventional cardiology procedures in a tertiary care hospital.

The aim of our investigation was to prospectively measure the patient radiation exposure from different cardiological procedures performed in the Catheterisation laboratory of the University Hospital Gasthuisberg in Leuven. The following local reference values were proposed: 40, 47 and 80 Gycm2 for coronary angiography (CA) or angioplasty (PTCA and stent implantation for elective patients), radio frequency ablation with angiographic images and CA plus ad hoc PTCA, respectively.