Evaluation of image-enhanced paediatric computed tomography brain examinations

Abstract

The aim of this study was to evaluate the possibility of reducing the radiation dose to paediatric patients undergoing computed tomography (CT) brain examination by using image-enhancing software. Artificial noise was added to the raw data collected from 20 patients aged between 1 and 10 y to simulate tube current reductions of 20, 40 and 60 mA. All images were created in duplicate; one set of images remained unprocessed whereas the other was processed with image-enhancing software. Three paediatric radiologists assessed the image quality based on their ability to visualise the high- and low-contrast structures and their overall impression of the diagnostic value of the image. For patients aged 6-10 y, it was found that dose reductions from 27 mGy (CTDI(vol)) to 23 mGy (15 %) in the upper brain and from 32 to 28 mGy (13 %) in the lower brain were possible for standard diagnostic CT examinations when using the image-enhancing filter. For patients 1-5 y, the results for standard diagnostics in the upper brain were inconclusive, for the lower brain no dose reductions were found possible.

Reducing radiation exposure from computed tomography of the brain in children — report of a practical approach

“…These measures also make it easier to carry out low dose CT studies which study the lower limit of radiation dose that [14,20]; overall, these values are low compared to the values from clinical audits [10,22,28]. In the present study, the tube current-time product used was comparable to those in low dose reports [14,20].…”

“…When a CT brain was ordered, one of the authors (STW) would then evaluate the patient according to the criteria listed in Table 1, to see if the patient was suitable for the LDSS protocol. Most importantly, the purpose of a CT brain should be specific such as comparing serial ventricle size or haematoma size, assessing ventricular catheter position, midline shift, and detecting significant post-operative changes such as haematoma, pneumocephalus, ventricular dilatation and increased midline shift; these were similar to the high contrast targets mentioned in the literature [14]. On the other hand, we excluded patients with acute deterioration in neurological condition which might require emergency treatment; we also excluded patients with high grade tumours because they were unlikely to benefit from reduction in radiation exposure in the diagnostic range.…”

“…When evaluating low dose CT brain, the tube voltage is usually kept constant, and the tube current-time product is usually the parameter to be modulated [3,14,20]. A third CT scanning parameter to be manipulated is the scan length which, in CT brain, is the length of the segment of the cranium being scanned.…”

“…The first component was the settings of the CT scanning parameters, derived with reference to published values (Table 2) [8,10,14,22,23,28] as well as the data accumulated during the study; the settings were as follows:…”

“…However, there is always practically a limit to advancement in technology that further radiation dose reduction leads to suboptimal image resolution [11,14].…”