Electron and photon spread contributions to the radiological penumbra for small monoenergetic x-ray beam (<=2 MeV)

Journal Article · Fri May 15 04:00:00 EDT 2009 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.3115667· OSTI ID:21352201

Pignol, Jean-Philippe ^[1]; Keller, Brian M ^[2]

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1. Department of Radiation Oncology, Sunnybrook Health Sciences Centre, University of Toronto, 2075 Bayview Avenue, Toronto, Ontario M4N3M5 (Canada)
2. Department of Medical Physics, Sunnybrook Health Sciences Centre, University of Toronto, 2075 Bayview Avenue, Toronto, Ontario M4N3M5 (Canada)

Our team has previously published that submegavoltage photons could significantly improve the radiological penumbra for small size radiation fields. The present work uses Monte Carlo simulation to evaluate the contributions of secondary electrons and photon scatter to the penumbra region for various field sizes (5, 10, 20, and 40 mm in diameters) and for various monoenergetic photon beams (200, 400, 600, 800, 1000, and 2000 keV, and a standard 6 MV beam), minimizing geometrical and transmission penumbra. For field sizes less than 2 cm in diameter, photon scatter is negligible such that the secondary electrons are the main contributor to the radiological penumbra. Reducing the photon beam energy to the submegavoltage range reduces the range of secondary electrons and eventually improves the beam boundary sharpness. Provided that the geometrical penumbra and patient immobilization system are optimized, submegavoltage photon beams with effective photon energies in the 300 to 600 keV range, present significant advantages for multiple beam stereotactic irradiations of tumors less than 2 cm in diameter.

• OSTI ID: 21352201
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 10 Vol. 105; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
BEAMS
CALCULATION METHODS
COMPUTERIZED SIMULATION
DISEASES
ELECTRON BEAMS
ENERGY RANGE
IRRADIATION
KEV RANGE
KEV RANGE 100-1000
LEPTON BEAMS
MEDICINE
MEV RANGE
MEV RANGE 01-10
MONTE CARLO METHOD
NEOPLASMS
NUCLEAR MEDICINE
PARTICLE BEAMS
PATIENTS
PHOTON BEAMS
RADIOLOGY
RADIOTHERAPY
SIMULATION
THERAPY