Optimising the use of computed radiography in pediatric chest imaging

Abstract

The objective of this study was to analyze image quality of chest examinations in pediatric patients using computed radiography (CR) obtained with a wide range of doses to suggest the appropriate parameters for optimal image quality. A sample of 240 chest images in four age ranges was randomly selected from the examinations performed during 2004. Images were obtained using a CR system and were evaluated independently by three radiologists. Each image was scored using criteria proposed by the European Guidelines on Quality Criteria in Pediatrics. Mean global scoring and scoring of individual criteria more sensitive to noise were used to evaluate image quality. Agfa dose level (DL) was in the range 1.20 to 2.85. It was found that there was not significant correlation (R < 0.5) between image quality and DL for any of the age ranges for either global score or for individual criteria more related to noise. The mean value of DL was in the ranges 1.9-2.1 for the four age bands. From this study, a DL value of 1.6 is proposed for pediatric CR chest imaging. This could yield a reduction of approximately a factor of 2.5 in mean patient entrance surface doses.

Fig 1.

Histogram of the typical pixel content in a CR image.

Fig 2.

Scoring of individual images versus DL values for the age band <1 year. Coefficient of determination (R²) is included.

Fig 3.

Scoring of individual images versus DL values for the age band 1 to <5 years. Coefficient of determination (R²) is included.

Fig 4.

Scoring of individual images versus DL values for the age band 5 to <10 years. Coefficient of determination (R²) is included.

Fig 5.

Scoring of individual images versus DL values for the age band 10 to <16 years. Coefficient of determination (R²) is included.

Fig 6.

Example of clinical image nonvalid for diagnosis because of the high noise level (DL = 1.05); 3-week-old patient.

Fig 7.

Example of clinical image nonvalid for diagnosis because of the saturation in some areas of the lung (DL = 2.95); 13-month-old patient.

Fig 8.

(a) Image of a premature infant obtained with a DL of 2.1 (representing in this case a value of patient ESD of 50 μGy). (b) Image of the same premature infant obtained 4 days later with a DL of 1.8 (representing in this case a value of patient ESD of 25 μGy).