Contribution of interventional cardiology to the collective dose in Spain.

INTRODUCTION AND OBJECTIVES: To estimate the contribution of interventional cardiology (IC) to the collective dose in Spain. METHODS: Using the information on frequencies of examinations sourced from the Spanish Society of Cardiology and the patient dose values obtained by the national DOCCACI programme. RESULTS: The fraction of the collective dose per million inhabitants derived from IC was 34 man-Sv (a total of 1600 man-Sv in Spain with 46.5 million inhabitants). The contribution of the IC derived from the medical use of x-rays in Spain resulted in 0.66% of the procedures and 4% of the x-ray collective dose. CONCLUSIONS: Even if this collective radiation dose may seem moderate, at an individual level this medical practice delivers the greatest doses and, therefore, optimisation remains of paramount importance.

Objective criteria for acceptability and constancy tests of digital subtraction angiography.

PURPOSE: Demonstrate an objective procedure to quantify image quality in digital subtraction angiography (DSA) and suggest thresholds for acceptability and constancy tests. METHODS: Series of images were obtained in a DSA system simulating a small (paediatric) and a large patient using the dynamic phantom described in the IEC and DIN standards for acceptance tests of DSA equipment. Image quality was quantified using measurements of contrast-to-noise ratio (CNR). Overall scores combining the CNR of 10-100 mg/ml Iodine at a vascular diameter of 1-4 mm in a homogeneous background were defined. Phantom entrance surface air kerma (Ka,e) was measured with an ionisation chamber. RESULTS: The visibility of a low-contrast vessel in DSA images has been identified with a CNR value of 0.50 ± 0.03. Despite using 14 times more Ka,e (8.85 vs 0.63 mGy/image), the protocol for large patients showed a decrease in the overall score CNRsum of 67% (4.21 ± 0.06 vs 2.10 ± 0.05). The uncertainty in the results of the objective method was below 5%. CONCLUSION: Objective evaluation of DSA images using CNR is feasible with dedicated phantom measurements. An objective methodology has been suggested for acceptance tests compliant with the IEC/DIN standards. The defined overall scores can serve to fix a reproducible baseline for constancy tests, as well as to study the device stability within one acquisition series and compare different imaging protocols. This work provides aspects that have not been included in the recent European guidelines on Criteria for Acceptability of Medical Radiological Equipment.