Dose evaluation in paediatric patients undergoing skull examinations

Abstract

The purpose of this study was to estimate the kerma-area product (KAP) and incident air kerma of radiographic skull examinations in a large paediatric hospital in Brazil. In addition, the influence of thickness on patient parameters and radiographic technique was verified. A total of 125 paediatric patients (69 males and 56 females) were evaluated, and 294 radiographs (125 projections in anteroposterior/posteroanterior and 123 in lateral, and 46 in Towne) were performed. To analyse the results, the patients were divided into age groups: 0–1 year, 1–5 years, 5–10 years, and 10–15 years. Anthropometric data of the patient (weight, height and thickness) and radiographic technique data (voltage, product current time and focus skin distance) were collected. The analysis of patients' thicknesses and other characteristics which can be used to determine radiographic protocols showed that thickness can be estimated from the patient's age, height, or weight with an uncertainty higher than 15%. The age groups, which are usually used to compare radiographic techniques, are not appropriate for data-oriented decisions. For practical purposes, we suggest the following groups with fixed radiographic protocols; age: <0.5 year, 0.5–1 year, and >1 year; height: 40–60 cm, 60–80 cm, and >80 cm; weight: <5 kg, 5–10 kg and >10 kg. There was a very small correlation between the patient dose and thickness, with a difference of up to 20-fold in dose for patients of the same thickness. If radiological protocols were to be standardized, it should be possible to keep the dose below ∼0.9 mGy. The correlation between the KAP and the patient's thickness is clearer; however, the dispersion of the KAP values is even greater, especially for anteroposterior/posteroanterior projection.