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Published on: September 11, 2011
Radiation dose for common pediatric computed tomography examinations and evaluation of clinical image quality in
I Findikli1, A Yalcin1, O Kasapgil1
1Institute of Nuclear Sciences, Ankara University, Ankara, 06830, Türkiye.
Insights
Pediatric CT scans show varying radiation doses across head, thorax, and abdomen exams. While iterative reconstruction algorithms improve objective image quality, clinical diagnostic quality did not significantly change, indicating a need for careful algorithm selection.
Area of Science:
- Medical Physics
- Radiology
- Pediatric Imaging
Background:
- Computed tomography (CT) use in children is rising, necessitating research into pediatric radiation doses and image quality optimization.
- Minimizing radiation exposure while maintaining diagnostic accuracy is crucial in pediatric CT examinations.
Purpose of the Study:
- To determine radiation doses (CTDIvol, SSDE, DLP) for pediatric head, thorax, and abdomen CT scans.
- To evaluate the impact of different iterative reconstruction (IR) algorithms on pediatric thorax CT image quality.
- To establish local diagnostic reference levels (DRLs) for pediatric CT examinations.
Main Methods:
- Radiation doses were measured across various CT systems in three university hospitals using CTDIvol, SSDE, and DLP metrics.
- Image quality of pediatric thorax CT scans (ages 4-6) was assessed using objective measures and visual grading analysis (VGAabs) with iDose4, ADMIRE, and ASiR algorithms.
- Interobserver agreement was calculated using the intraclass correlation coefficient (ICC).
Main Results:
- Median CTDIvol/DLP values were 31.6 mGy/541.3 mGy·cm (head), 2.1 mGy/30.1 mGy·cm (thorax), and 2.2 mGy/39.8 mGy·cm (abdomen).
- Median SSDE for pediatric thorax and abdomen CT were 4.7 mGy and 4.6 mGy, respectively.
- Noise decreased and SNR/CNR increased with higher IR iteration levels; however, clinical image quality (VGAabs) showed no significant improvement and sometimes decreased with increasing IR levels. Interobserver agreement varied from poor to good across algorithms.
Conclusions:
- Objective image quality in pediatric CT improves with higher iterative reconstruction (IR) levels.
- Clinical diagnostic image quality does not consistently improve with increasing IR levels, suggesting that higher iterations may not enhance diagnostic utility.
- Careful selection of IR algorithms and iteration levels is recommended to balance objective image quality improvements with actual diagnostic performance in pediatric CT.
Abstract:
The increasing use of computed tomography (CT) in pediatric patients has prompted researchers to investigate the radiation dose associated with pediatric CT scans. Studies optimizing image quality and minimizing radiation dose in pediatric CT examinations continue to increase each year. This study aimed to determine the radiation doses received by pediatric patients during CT scans of the head, thorax, and abdomen, and to evaluate the image quality of pediatric thorax CT images using different iterative reconstruction (IR) algorithms. The study was conducted on CT systems of various brands and models installed in three major university hospitals in Ankara. Radiation doses for pediatric head, thorax, and abdomen CT examinations were measured in volume computed tomography dose index (CTDIvol), size-specific dose estimate (SSDE), and Dose length product (DLP), and local diagnostic reference level (DRL) was determined for each examination. Image quality was evaluated from thorax CT images of children aged 4-6 years, objectively and clinically, depending on different IR algorithms (iDose4, advanced modeled iterative reconstruction (ADMIRE), and adaptive statistical iterative reconstruction (ASiR)). Median CTDIvol/DLP values for pediatric head/thorax/abdomen CT were 31.6 mGy/541.3 mGy cm, 2.1 mGy/30.1 mGy cm, and 2.2 mGy/39.8 mGy cm, respectively. The median SSDE (mGy) calculated according to the American Association of Physicists in Medicine (AAPM) 220 report for pediatric thorax and abdomen CT scans were 4.7 and 4.6 mGy. The noise decreased with increasing iteration level for each IR algorithm, while the SNR and CNR increased. Absolute visual grading analysis (VGAabs), which gives clinical image quality, did not increase or even decrease with increasing IR level, except for one CT system. The interobserver agreement was poor (ICC = 0.29, p = 0.30), moderate (ICC = 0.72, p = 0.04), and good (ICC = 0.84, p = 0.02) for images created with iDose4, ADMIRE and ASiR, respectively. While the objective image quality improves with each IR algorithm's increasing iteration level, no significant change in clinical diagnostic quality was observed.
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