Final answer:
The first primitive CT scanner invented by Sir Godfrey Hounsfield used x-rays as the source of radiation, which is standard for most medical imaging techniques.
Step-by-step explanation:
The source of radiation used in Sir Godfrey Hounsfield's first primitive CT scanner was x-rays. This aligns with the general concept that x-rays are typically used in medical imaging to create images of the body's interior structure. X-rays are a form of electromagnetic radiation, which can penetrate the body and allow for the visualization of internal organs, bones, and other structures. The use of x-rays in CT scans is based on their ability to capture multiple cross-sectional views of the body, which are then processed by a computer to generate a three-dimensional image of the scanned area.