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Evaluation of low-dose pediatric chest CT examination using in-house developed various age-size pediatric chest
Dafa Miftahuddin1, Audiena Gelung Prayitno1, Aditya Prayugo Hariyanto1
1Department of Physics, Institut Teknologi Sepuluh Nopember, Kampus ITS - Sukolilo Surabaya 600111, East Java, Indonesia.
Insights
Developing pediatric chest phantoms (VAPC) revealed that smaller children receive higher radiation doses during low-dose CT scans. Optimizing protocols with low kV and iterative reconstruction improves image quality and noise reduction for pediatric patients.
Area of Science:
- Medical Imaging Physics
- Pediatric Radiology
- Radiation Dosimetry
Background:
- Pediatric patients present unique challenges in CT imaging due to significant variations in size and age.
- Optimizing low-dose CT protocols is crucial to minimize radiation exposure while maintaining diagnostic image quality in children.
Purpose of the Study:
- To develop Various Age-size Pediatric Chest Phantoms (VAPC) for evaluating low-dose CT protocols.
- To assess organ-specific doses and image quality parameters under different low-dose CT conditions in pediatric phantoms.
Main Methods:
- VAPC phantoms were created based on pediatric data from 1, 4, and 7-year-olds.
- Six CT protocols (standard dose, low mA, low kV) using Filtered Back Projection (FBP) and iterative reconstruction (IR) were evaluated.
- Organ doses (lungs, heart, spinal cord) were measured, and image quality metrics (linearity, MTF, CNR, NPS) were assessed.
Main Results:
- Mean organ-specific doses exceeded CTDIvol, with younger phantoms receiving significantly higher lung doses.
- Low kV protocols resulted in lower organ doses compared to low mA protocols.
- Age significantly impacted organ dose, MTF, CNR, and NPS, while CT number linearity remained unbiased at low doses.
Conclusions:
- Smaller pediatric patients are exposed to higher doses in low-dose CT, while larger children exhibit reduced contrast resolution and increased noise.
- Low kV combined with FBP enhanced spatial resolution.
- Low mA with IR improved noise reduction for better detection of low-contrast objects.
Purpose:
This study aims to develop Various Age-size Pediatric Chest Phantoms (VAPC) to evaluate low-dose protocol that approximates clinical conditions achieved by low organ-specific doses and optimal image quality among the challenges of pediatric size variations.
Methods:
Three original pediatric data aged 1, 4, and 7 years were used as a reference for developing VAPC phantoms. Six protocols, namely standard dose (STD) and low dose (low mA and low kV) reconstructed using Filtered Back Projection (FBP) and iterative reconstruction (IR) algorithms, were investigated. This study directly measured the lungs, heart, and spinal cord dose using LD-V1 film. Linearity, Modulation Transfer Function (MTF), Contrast to Noise Ratio (CNR), and Noise Power Spectrum (NPS) were evaluated to assess the CT image quality of the VAPC phantom.
Results:
This study found that the mean organ-specific dose was higher than CTDIvol. A Comparison of mean lung doses showed VAPC phantom 1 (y.o.) received 74.8% and 137.2% more doses than 4 (y.o.) and 7 (y.o.), respectively. Low kV produces a lower organ dose than low mA. The linearity of CT numbers is not biased at low doses. Differences in age measures significantly influenced organ-specific dose, MTF, CNR, and NPS.
Conclusion:
Smaller pediatrics are still exposed to higher doses at low-dose examinations, whereas larger pediatrics have lower contrast resolution and increased image noise. CT number linearity is unbiased. The combination of low kV with FBP produces higher spatial resolution, while low mA with IR effectively reduces noise to detect low-contrast objects better.
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