Radiology in the neonatal intensive care unit: dose reduction and image quality

Abstract

This paper describes a prospective study of the diagnostic radiation doses received in a neonatal intensive care unit (NICU) for a representative radiological technique used at our institution for a number of years and a "low dose" technique similar to that recommended by the Commission of the European Communities (CEC). A 400 speed film-screen combination was used in both techniques. A total of 363 anteroposterior (AP) chest and abdominal films of 77 neonates were accrued. For each radiograph, the entrance skin dose (FSD), energy imparted (EI) and mean whole body dose were determined. For a neonatal AP chest, there was an 18% reduction in the mean ESD per radiograph from 20.0 muGy for the representative technique to 16.4 muGy for the low dose technique (p < 0.0005). The reduction in the mean EI per radiograph values for the two techniques from 7.9 muJ to 7.1 muJ (10%) was statistically significant at the p < 0.017 level, after compensating for the difference in mean field dimensions between the two patient cohorts. The mean whole body dose per radiograph reduction from 4.4 to 3.5 muGy (20%) was statistically significant at the p < 0.0028 level. It was determined that the ESD and EI could be fitted by an exponential function in the equivalent patient diameter, a single parameter indicative of neonate size. Absolute excess childhood cancer mortality risk per film was estimated using risk factors derived for fetal exposures. A "worst case" absolute excess mortality risk per chest radiograph was estimated to be 1.40 x 10(-7) for the conventional technique and was further reduced to 1.11 x 10(-7) for the low dose technique. A blind comparison of patient-matched film pairs for each technique was performed by three radiologists using criteria similar to those specified by the CEC. No statistically significant difference in clinical image quality was found between the two techniques.

Do CEC guidelines under-utilise the full potential of increasing kVp as a dose-reducing tool?

“…Some discrepancies were noted between the levels of reduction seen between the patient and phantom studies, but these were minor and such discrepancies have been reported elsewhere [19]. The reductions described in this study compare well with those of previous workers who explored raised kVps for spine radiography [6,7,20] and other X-ray examinations [10,11].…”

“…As beam energy is increased, X-rays become more penetrating, are less likely to be attenuated within the patient and are more likely to reach the image receptor compared with lower beam energies. This results in radiation dose reductions of over 50% [1] and higher beam energy have been shown to be an effective dose-reducing tool for a number of examination types including plain-film radiography [2,3,4,5,6,7,8], digital procedures [9] and paediatric radiology [10,11]. Although these dose reductions are laudable, it must be noted that increased energy may have a negative effect on image contrast as a result of a higher proportion of Compton interactions and more forward scatter reaching the image receptor.…”

Comparison of the perceived image quality between two digital imaging systems for neonatal bedside radiography – A case study

“…The data collection instrument used for this study was a self-designed image analysis form. To ensure validity, this form was derived from the image analysis protocol set by Mcquillen-Martenson 9 as well as the standardised technique recommended by the Commission of the European Communities 10 .…”

Entrance skin dose estimates derived from dose-area product measurements in interventional radiological procedures.

“…The known. While it has been reported that the technology to determine the ESD from the DAP on interventional radiology units is under developestimates of the ESD for a given IR procedure if field [13], the entrance skin dose can be related to the DAP: the following assumptions are valid: where A II is the field area measured at the FID. $ the image intensifier field-of-view (IIw) is reasonDue to positive beam limitation, A II has an explicit ably fixed and consistent between procedures.…”