Skip to content

Course home

Sign up

Medical imaging

EasyMedium
12345678910111213141516171819202122
Question 12

During a Positron Emission Tomography (PET) scan, a positron emitted by a radiopharmaceutical annihilates with a nearby electron in the patient's tissue. This process produces two identical gamma-ray photons traveling in opposite directions.

Assuming the kinetic energies of both particles are negligible prior to annihilation, what is the wavelength of each emitted gamma-ray photon?

Data:

  • Rest mass of an electron, me=9.11×10−31 kgm_e = 9.11 \times 10^{-31}\text{ kg}me​=9.11×10−31 kg
  • Speed of light in a vacuum, c=3.00×108 m s−1c = 3.00 \times 10^8\text{ m s}^{-1}c=3.00×108 m s−1
  • Planck constant, h=6.63×10−34 J sh = 6.63 \times 10^{-34}\text{ J s}h=6.63×10−34 J s
A

1.21×10−12 m1.21 \times 10^{-12}\text{ m}1.21×10−12 m

B

2.43×10−12 m2.43 \times 10^{-12}\text{ m}2.43×10−12 m

C

4.86×10−12 m4.86 \times 10^{-12}\text{ m}4.86×10−12 m

D

1.32×10−15 m1.32 \times 10^{-15}\text{ m}1.32×10−15 m

Markscheme

Medical imaging Questions

  1. A Level
  2. /Physics
  3. /Medical imaging

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.

Question bank