Individualized volume CT dose index determined by cross-sectional area and mean density of the body to achieve uniform image noise of contrast-enhanced pediatric chest CT obtained at variable kV levels and with combined tube current modulation

Background

A practical body-size adaptive protocol providing uniform image noise at various kV levels is not available for pediatric CT.

Objective

To develop a practical contrast-enhanced pediatric chest CT protocol providing uniform image noise by using an individualized volume CT dose index (CTDIvol) determined by the cross-sectional area and density of the body at variable kV levels and with combined tube current modulation.

Materials and methods

A total of 137 patients (mean age, 7.6?years) underwent contrast-enhanced pediatric chest CT based on body weight. From the CTDIvol, image noise, and area and mean density of the cross-section at the lung base in the weight-based group, the best fit equation was estimated with a very high correlation coefficient (??²?=?0.86, P?Results The CTDIvol values (mean±standard deviation, 1.6?±?0.7?mGy) and the noise differences from the target noise (1.1?±?0.9?HU) of the CTDIvol group were significantly lower than those of the weight-based group (2.0?±?1.0?mGy, 1.8?±?1.4?HU) (P?2 vs. 326.3?±?124.8 cm²), mean density (?212.9?±?53.1?HU vs. ?221.1?±?56.3?HU), and image noise (13.8?±?2.3 vs. 13.6?±?1.7?HU) between the weight-based and the CTDIvol groups (P?>?0.05).

Conclusion

Contrast-enhanced pediatric chest CT with the CTDIvol determined individually by the cross-sectional area and density of the body provides more uniform noise and better dose adaptation to body habitus than does weight-based CT at variable kV levels and with combined tube current modulation.