Photon Beam Dose Calculation Algorithms. Kent A. Gifford, Ph.D. Medical Physics III Spring 2010. Dose Computation Algorithms. Correction-based (Ancient!) Convolution (Pinnacle,Eclipse,…) Monte Carlo (Stochastic) Deterministic (Non-stochastic). Photon Source. Standard SSD. Patient
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Kent A. Gifford, Ph.D.
Medical Physics III Spring 2010
Calculations (Correction Factors)Correction-based algorithms
Correction factors for:
1. Wedges- WF, wedged profiles
2. Compensators- attenuation measurements
3. Blocks- OF
Attenuation corrections due to “missing” tissue
1. TMR ratio: CF=TMReff /TMRphysical
rPrimary and Scatter Concepts
Dose spread array
Iso energy distribution lines.2’ interactions
e- Several algorithmsMonte Carlo(Gambling)
Monte Carlo Several algorithms
↑Angular fluence rate
↑macroscopic total cross section
extrinsic source ↑
Dimensions in cm
Run time*: 13.7 mins, 97% points w/in 5%, 89% w/in ±3%
*MCNPX: 2300 mins
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