Proton Bragg curves in water for 67.5 MeV protons

Authors: Bruce Faddegon, Jungwook Shin and Jose' Ramos-Méndez, University of California, San Francisco, US

Short description: A 67.5 MeV proton beam with a Gaussian energy spread of 0.4 MeV, and a uniform 5 mm x 10 mm oval spot travels through a tantalum (Ta) foil of either 101.6 micrometer or 381 micrometer thickness. Then the beam interacts with a secondary emission monitor (SEM) and a kapton exit window before reaching a mylar wall and water phantom of 280 mm x 280 mm x 50 mm with back surface located downstream the Mylar wall.

Geant-val layout: LowEProtonBraggBeak

Reference data: The depth-dose curves in water (ionization potential I=78 eV) are calculated and then fitted with an analytical expression for the Bragg curve. The fitting parameters range R and spread sigma are compared against the corresponding experimental parameters from depth-dose measurement from [1]

[1] Faddegon B, Shin J, Castenada C M, Ramos-Méndez J and Daftari I K Experimental depth dose curves of a 67.5 MeV proton beam for benchmarking and validation of Monte Carlo simulation Med. Phys. 42 4199–210 (2015)

Tested EM physics constructors:

• G4EmStandardPhysics_option3
• G4EmStandardPhysics_option4
• G4EmLivermorePhysics
• G4EmPenelopePhysics

Tested Hadronic physics:

• QGSP_BIC_HP

-- SusannaGuatelli - 2019-04-18