Question

Biomedical Imaging (x-rays); Please show all work!

Specialized X-ray imaging methods 2.16 In mammographic examinations, the breast is compressed between two plates. Answer the following with a brief explanation (a) Is the geometric unsharpness increased or decreased by compression? (b) hy is the image contrast improved by this procedure? (c) Is the required x-ray dose for a given image SNR higher or lower with compression?

Answer 1

a) The geometric unsharpness is decreased by compression because the breast tissue is brought closer to the image plane with the help of compression. Compression also helps in reducing motion unsharpness

b) The image contrast is improved by this procedure because compression does not allow the X-rays to scatter, and denser the breast tissue, more improved is the contrast sensitivity.

c) The required X-ray dose for a given image is lower with compression because the thickness of the breast tissue is reduced by compression. Reduced thickness in turn reduces the radiation dose which is required for imaging. Exposure time is also shorter.