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. 2012 Feb 23:8313:831357.
doi: 10.1117/12.910945.

Dose Reduction Technique Using a Combination of a Region of Interest (ROI) Material X-Ray Attenuator and Spatially Different Temporal Filtering for Fluoroscopic Interventions

S N Swetadri Vasan  1 , A Panse, A Jain, P Sharma, Ciprian N Ionita, A H Titus, A N Cartwright, D R Bednarek, S Rudin
Affiliations

Dose Reduction Technique Using a Combination of a Region of Interest (ROI) Material X-Ray Attenuator and Spatially Different Temporal Filtering for Fluoroscopic Interventions

S N Swetadri Vasan et al. Proc SPIE Int Soc Opt Eng. .

Abstract

We demonstrate a novel approach for achieving patient dose savings during image-guided neurovascular interventions, involving a combination of a material x-ray region of interest (ROI) attenuator and a spatially different ROI temporal filtering technique. The part of the image under the attenuator is reduced in dose but noisy and less bright due to fewer x-ray quanta reaching the detector, as compared to the non-attenuating (or less attenuating) region. First the brightness is equalized throughout the image by post processing and then a temporal filter with higher weights is applied to the high attenuating region to reduce the noise, at the cost of increased lag; however, in the regions where less attenuation is present, a lower temporal weight is needed and is applied to preserve temporal resolution. A simulation of the technique is first presented on an actual image sequence obtained from an endovascular image guided interventional (EIGI) procedure. Then the actual implementation of the technique with a physical ROI attenuator is presented. Quantitative analysis including noise analysis and integral dose calculations are presented to validate the proposed technique.

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Figures

Figure 1
Figure 1
An example of image mask used for subtraction to equalize brightness throughout the image. A - non attenuating region (ROI) B - attenuating region
Figure 2
Figure 2
ROI fluoroscopy - work flow
Figure 3
Figure 3
Image from patient procedure reduced in brightness and mixed with noise outside the ROI
Figure 4
Figure 4
Image in Fig. 3 with brightness corrected
Figure 5
Figure 5
Image in Fig 3 with brightness corrected and higher temporal weight outside the ROI (k = 5)
Figure 6
Figure 6
Input image of a skull phantom with ROI attenuator in the beam
Figure 7
Figure 7
Image in Fig. 6 with brightness corrected. Colored boxes show sampled regions for quantitative evaluation.
Figure 8
Figure 8
Image in Fig. 6 with brightness corrected and higher temporal weight outside the ROI (k = 5)
Figure 9
Figure 9
An image with brightness equalized in both regions and a temporal filter weight of 1.0 applied in the periphery. ROI attenuator stack - 4 layers, attenuation factor – 6 x
Figure 10
Figure 10
An image with brightness equalized in both regions and a temporal filter weightof 0.4 in the periphery and 0.8 in the ROI. ROI attenuator stack - 4 layers, attenuation factor – 6x
Figure 11
Figure 11
An image with brightness equalized in both regions, and a temporal filter weight of 1.0 applied in the periphery. ROI attenuator stack - 8 layers, attenuation factor – 14 x
Figure 12
Figure 12
An image with brightness equalized in both regions, and temporal filter weight of 5 in the periphery and 1.25 in the ROI. ROI attenuator stack -8 layers, attenuation factor – 14 x
See this image and copyright information in PMC

References

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