Evaluation of an organ-based tube current modulation tool in pediatric CT examinations
Antonios E Papadakis1, John Damilakis2
1Department of Medical Physics, University Hospital of Heraklion, Stavrakia, 71110, Heraklion, Crete, Greece. apapadak@pagni.gr.
Insights
Organ-based tube current modulation (OTCM) in pediatric CT scans significantly reduces radiation dose to radiosensitive organs like the eyes and breast buds. However, this technique inevitably increases image noise within the activated volume.
Area of Science:
- Medical Physics
- Radiological Imaging
- Pediatric Radiology
Background:
- Computed tomography (CT) is crucial in pediatric diagnostics, but radiation dose optimization remains a priority.
- Organ-based tube current modulation (OTCM) is an advanced technique designed to tailor radiation exposure to specific organs.
- Assessing the impact of OTCM on dose reduction and image quality in pediatric patients is essential for safe and effective imaging.
Purpose of the Study:
- To evaluate the effectiveness of organ-based tube current modulation (OTCM) in reducing organ absorbed dose during pediatric CT examinations.
- To assess the impact of OTCM on image quality, specifically image noise, in pediatric CT.
- To investigate the relationship between OTCM parameters and radiation dose reduction.
Main Methods:
- Utilized four anthropomorphic phantoms representing neonate, 1-year-old, 5-year-old, and 10-year-old individuals.
- Performed standard head and thorax CT acquisitions using automatic tube current modulation (ATCM) and ATCM with OTCM (ATCM+OTCM).
- Employed Monte Carlo simulations for dose calculations and measured organ doses, alongside image noise assessment via Hounsfield unit standard deviation.
Main Results:
- ATCM+OTCM demonstrated a reduction in radiation dose to all evaluated radiosensitive organs.
- Eye lens dose decreased by up to 13% and breast dose by up to 10% with ATCM+OTCM compared to ATCM.
- A significant increase in image noise was observed in ATCM+OTCM acquisitions across most phantoms (p < 0.05).
Conclusions:
- Organ-based tube current modulation (OTCM) effectively reduces radiation dose to key radiosensitive organs in pediatric CT.
- The observed increase in image noise within the OTCM-activated volume is an inherent trade-off.
- The angular range of the OTCM exposure window is inversely related to tube rotation time, narrowing with shorter rotation durations.
Objectives:
To investigate the effect of an organ-based tube current modulation (OTCM) technique on organ absorbed dose and assess image quality in pediatric CT examinations.
Methods:
Four physical anthropomorphic phantoms that represent the average individual as neonate, 1-year-old, 5-year-old, and 10-year-old were used. Standard head and thorax acquisitions were performed with automatic tube current modulation (ATCM) and ATCM+OTCM. Dose calculations were performed by means of Monte Carlo simulations. Radiation dose was measured for superficial and centrally located radiosensitive organs. The angular range of the OTCM exposure window was determined for different tube rotation times (t) by means of a solid-state detector. Image noise was measured as the standard deviation of the Hounsfield unit value in regions of interest drawn at selected anatomical sites.
Results:
ATCM+OTCM resulted in a reduction of radiation dose to all radiosensitive organs. In head, eye lens dose was reduced by up to 13% in ATCM+OTCM compared with ATCM. In thorax, the corresponding reduction for breast dose was up to 10%. The angular range of the OTCM exposure window decreased with t. For t = 0.4 s, the angular range was limited to 74° in head and 135° for thorax. Image noise was significantly increased in ATCM+OTCM acquisitions across most examined phantoms (p < 0.05).
Conclusions:
OTCM reduces radiation dose to exposed radiosensitive organs with the eye lens and breast buds exhibiting the highest dose reduction. The OTCM exposure window is narrowed at short t. An increase in noise is inevitable in images located within the OTCM-activated imaged volume.
Key Points:
• In pediatric CT, organ-based tube current modulation reduces radiation dose to all major primarily exposed radiosensitive organs. • Image noise increases within the organ-based tube current modulation enabled imaged volume. • The angular range of the organ-based tube current modulation low exposure window is reduced with tube rotation time.
Related Concept Videos
01:10Computed Tomography
The technique was invented in the 1970s and is based on the principle that as X-rays pass through the body, they are absorbed or reflected at different levels. In the technique, a patient lies on a motorized platform while a computerized axial tomography (CAT) scanner rotates...
01:28Imaging Studies for Cardiovascular System V: CT