Radiation dose optimisation in paediatric head CT using attenuation-based auto prescription
Michael Zellner1,2, Selma Sirin3,4, Nadja Kocher3,4
1University Children's Hospital Zurich, Department of Diagnostic Imaging, Zurich, Switzerland. michael.zellner@kispi.uzh.ch.
Insights
An Auto Prescription protocol for paediatric head CT scans uses patient attenuation to optimize radiation dose, achieving significant reductions in younger and older children. Image quality remained diagnostically adequate and non-inferior to age-based methods.
Area of Science:
- Medical Imaging
- Radiology
- Paediatric Imaging
Background:
- Minimizing ionizing radiation is critical in pediatric imaging due to heightened sensitivity in children.
- Evaluating automated protocols is essential for optimizing radiation dose and image quality in pediatric CT scans.
Purpose of the Study:
- To assess an attenuation-based Auto Prescription protocol for pediatric head CT.
- To compare its radiation dose and image quality against traditional age-based protocols.
Main Methods:
- An Auto Prescription protocol was implemented on a 256-slice scanner, adjusting kV and mAs based on scout image attenuation.
- Radiation dose parameters (CTDIvol, SSDE, ED, DLP) and image quality metrics (SNR, CNR, Likert scale) were evaluated.
- Data from 79 Auto Prescription studies were compared to 68 age-based protocol studies using non-parametric tests.
Main Results:
- The Auto Prescription protocol demonstrated a more balanced radiation dose distribution across pediatric age groups and head sizes.
- Significant dose reductions were observed, particularly in the 0-1 year (48.2%) and 10-15 year (40.4%) age groups (p < 0.001).
- While diagnostic image quality was adequate, objective metrics (SNR, CNR) were slightly lower, yet subjective quality parameters were statistically non-inferior (p < 0.05).
Conclusions:
- Attenuation-based Auto Prescription provides a more homogeneous and head density-adapted radiation dose in pediatric head CT.
- This automated approach achieves non-inferior diagnostic image quality while enabling significant radiation dose reduction.
- Individualized scan settings based on patient attenuation, rather than age alone, offer a secondary benefit of dose reduction.
Abstract:
Minimizing ionizing radiation is crucial in paediatric imaging due to children's increased radiation sensitivity, especially at younger ages. To evaluate a CT attenuation-based Auto Prescription protocol for paediatric head imaging, testing whether it provides image quality and radiation dose comparable to age-based protocols. Auto Prescription was implemented on a 256-slice scanner for axial volumetric head CT, adjusting kV and mAs based on attenuation data from scout images. Radiation dose parameters (CTDIvol, SSDE, ED, DLP) and image quality metrics (SNR, CNR, subjective Likert scale from 1-unacceptable to 4-higher than needed) were assessed in 79 consecutive studies using Auto Prescription protocols. These were compared to 68 studies obtained with age-based protocols using non-parametric tests. A total of 147 patients (60 females, mean age 6.7 ± 5.1 years) were included. The auto prescription group included 29 patients aged 0-5, 20 aged 5-10, 25 aged 10-15, and 5 over 15 years; the age-based group included 36, 18, 9, and 5 patients respectively in the same age groups. The Auto Prescription protocol achieved a more balanced radiation dose distribution across age and water-equivalent diameter. The greatest dose reduction was observed in the 0-1 year (48.2%, p < 0.001) and 10-15 year (40.4%, p < 0.001) age groups. While diagnostic image quality was adequate in both settings, it was lower with the auto prescription protocols (mean image quality 3.0 ± 0.2 versus 2.8 ± 0.2; SNR 7.2 ± 1.5 vs. 5.1 ± 1.1; CNR 0.9 ± 0.5 vs. 0.7 ± 0.2; all p < 0.001). All subjective image quality parameters were statistically non-inferior to the age- based protocol (p < 0.05). Attenuation-based Auto Prescription resulted in a more homogeneous and head density adapted radiation dose across paediatric patients, with non-inferior image quality. Dose reduction was a secondary benefit of individualized scan settings based on patient attenuation rather than age alone.
