Question

The Bragg peak effect is most pronounced in:

• A. X-ray
• B. Proton
• C. Neutron
• D. Electron

Hint:

Heavy charged particles dump their dose at a defined depth before stopping.

Answer 1

The Correct Option is B

Step 1: The Bragg peak describes the way a charged particle beam deposits most of its energy at a specific depth, near the end of its range, with little dose beyond that point. Step 2: Protons are heavy charged particles. As they slow in tissue they deposit a sharply rising dose that peaks just before they stop, giving the classic inverted depth-dose profile used in proton therapy. Step 3: Photons (X-rays) show an exponential fall-off of dose with depth after the build-up region, so they have no Bragg peak. Electrons are light charged particles that scatter and have a finite range but a much broader, less sharply defined peak. Neutrons are uncharged and deposit dose more diffusely without a defined Bragg peak. Step 4: Combining several proton energies produces a Spread-Out Bragg Peak to cover a tumour volume. Hence the Bragg peak is most pronounced with protons.