From the Guidelines
A dual energy CT scan typically emits between 1-5 millisieverts (mSv) of radiation, depending on the specific protocol and equipment used. This estimate is based on recent advancements in CT technology, including dose reduction strategies and optimized scanning protocols 1. The radiation dose from dual energy CT is generally comparable to or slightly higher than conventional single-energy CT scans. Dual energy technology captures images at two different energy levels, providing enhanced tissue characterization and material differentiation, which may require a slightly higher radiation dose. However, modern dual energy CT scanners incorporate dose reduction technologies, such as tube current modulation and X-ray beam filtration, to minimize radiation exposure while maintaining diagnostic image quality 1.
Some key factors that influence the radiation dose of a dual energy CT scan include:
- Scan length: Keeping the scan length to a minimum to encompass only the anatomy of interest can help reduce radiation exposure 1
- X-ray beam intensity: Adjusting the X-ray tube potential and current can help minimize radiation dose while maintaining image quality 1
- Rotation time: Exposure increases linearly with rotation time, so shorter rotation times can help reduce radiation dose 1
- X-ray beam filtration: Using filters to selectively attenuate low-energy X-rays can help reduce radiation dose while maintaining image quality 1
For context, a standard chest X-ray emits about 0.1 mSv, making a dual energy CT scan approximately 10-50 times more radiation. While this amount of radiation carries a small theoretical increased cancer risk, the diagnostic benefits typically outweigh this risk when the scan is medically necessary. Recent studies have demonstrated the effectiveness of dual energy CT in various clinical applications, including cardiovascular imaging 1. Overall, the radiation dose from a dual energy CT scan should be carefully considered and minimized whenever possible, while still maintaining diagnostic image quality.
From the Research
Radiation Emission in Dual Energy CT Scans
- The amount of radiation emitted by a dual energy CT scan can vary depending on the specific protocol and scanner used 2, 3.
- A study published in 2010 found that the effective dose measured with thermoluminescent detectors was 2.61,2.69, and 2.70 mSv for different dual energy CT protocols, which was comparable to the standard 120 kVp scan 2.
- Another study published in 2020 found that dual energy CT scans of the abdomen and pelvis had significantly lower radiation doses than single energy CT scans, with average CTDIvol and DLP values of 10.9 mGy and 534.8 mGy cm, respectively, compared to 14.7 mGy and 681.5 mGy cm for single energy CT scans 3.
- The use of dual energy CT can also help reduce radiation dose by allowing for the creation of virtual non-contrast images, which can eliminate the need for additional scans 4.
Factors Affecting Radiation Emission
- The radiation dose of a dual energy CT scan can be affected by factors such as the scanner used, the protocol employed, and the patient's size and weight 2, 3.
- The use of different x-ray spectra and beam energies can also impact the radiation dose, with some protocols resulting in lower doses than others 2.
- The development of new technologies and algorithms for dual energy CT is ongoing, and these advancements may lead to further reductions in radiation dose in the future 5.
Comparison to Single Energy CT Scans
- Dual energy CT scans have been shown to have comparable or lower radiation doses than single energy CT scans in some studies 2, 3.
- The use of dual energy CT can also provide additional benefits, such as improved image quality and the ability to create virtual non-contrast images, which can enhance diagnostic accuracy and reduce the need for additional scans 3, 4.