Korean J Radiol.  2017 ;18(4):722-728. 10.3348/kjr.2017.18.4.722.

Radiation Dose Reduction without Compromise to Image Quality by Alterations of Filtration and Focal Spot Size in Cerebral Angiography

• Kim DJ
• Park MK
• Jung DE
• Kang JH
• Kim BM

• KMID: 2427241
• DOI: http://doi.org/10.3348/kjr.2017.18.4.722

Abstract

OBJECTIVE
Different angiographic protocols may influence the radiation dose and image quality. In this study, we aimed to investigate the effects of filtration and focal spot size on radiation dose and image quality for diagnostic cerebral angiography using an in-vitro model and in-vivo patient groups.
MATERIALS AND METHODS
Radiation dose and image quality were analyzed by varying the filtration and focal spot size on digital subtraction angiography exposure protocols (1, inherent filtration + large focus; 2, inherent + small; 3, copper + large; 4, copper + small). For the in-vitro analysis, a phantom was used for comparison of radiation dose. For the in-vivo analysis, bilateral paired injections, and patient cohort groups were compared for radiation dose and image quality. Image quality analysis was performed in terms of contrast, sharpness, noise, and overall quality.
RESULTS
In the in-vitro analysis, the mean air kerma (AK) and dose area product (DAP)/frame were significantly lower with added copper filtration (protocols 3 and 4). In the in-vivo bilateral paired injections, AK and DAP/frame were significantly lower with filtration, without significant difference in image quality. The patient cohort groups with added filtration (protocols 3 and 4) showed significant reduction of total AK and DAP/patient without compromise to the image quality. Variations in focal spot size showed no significant differences in radiation dose and image quality.
CONCLUSION
Addition of filtration for angiographic exposure studies can result in significant total radiation dose reduction without loss of image quality. Focal spot size does not influence radiation dose and image quality. The routine angiographic protocol should be judiciously investigated and implemented.

Keyword

Radiation dose reduction; Radiation risk; Radiation safety; Radiation exposure; Cerebral angiography

MeSH Terms

Aged
Angiography, Digital Subtraction
Cerebral Angiography/*methods
Female
Humans
Imaging, Three-Dimensional
Male
Middle Aged
Radiation Dosage
Silicones/chemistry
Silicones

Figure

• 

  Fig. 1 Anteroposterior views of bilateral paired internal carotid artery (ICA) injections (Rt ICA, protocol 4; Lt ICA, protocol 1).Number of exposures, field of view, table height, source to distance, and tube angulations were matched for both injections. Despite lack of perceptible difference in image quality, about 40–50% of total AK and 25–40% of total DAP reduction was seen in patients studied with protocol 4. AK = air kerma, DAP = dose area product

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