This question is about the principles of diagnostic medical ultrasound.
In medical ultrasound imaging, a coupling gel is applied to the patient's skin. Explain, in terms of acoustic impedance, why this gel is necessary and describe the effect of omitting it.
An A-scan (Amplitude scan) is a common technique used to measure distances within the body. Explain how an A-scan can be used to determine the thickness of a patient's subcutaneous fat layer.
25 exam-style questions on OCR A A Level Physics Medical imaging, covering Using X-rays, Diagnostic methods in medicine, and Using ultrasound. Each one has a worked solution and a mark scheme showing where the marks go.