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SPECT-IMAGE RECONSTRUCTION PROCESS

Physics

SPECT-IMAGE RECONSTRUCTION PROCESS

1. Creation of 1D profiles from each projection angle - as the camera rotates around, it creates a 1 dimensional view of the measured radioactivity for each angle.

2. Filtering of profiles - compromise between noise reduction (degree of smoothing) and preservation of image (resolution). Smoothing usually defined by cut-off or critical frequency of the filter (maximum spatial frequency present in image).

3. Processing of data to create reconstructed slice image using back projection or iterative reconstruction of the filtered profiles.

4. Correcting for attenuation using:
- Analytical method: apply algorithm that assumes uniform attenuation and then adjusts pixel counts depending on distance from camera and edge of patient.
- Direct measurement: CT data can be used to calculate an attenuation map and adjust the pixel counts according to this.


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REFERENCES

1. Bushberg, J. T. (2012). The essential physics of medical imaging. Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins. Find it at Amazon
2. Heggie, J. C., Liddell, N. A., & Maher, K. P. (1997). Applied imaging technology. Melbourne: St. Vincents Hospital.

Ⓒ A. Manickam 2018

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