### New Registration Deadlines start winter quarter. So Register Early!

• The last day to register online is January 4th!
• Instructor permission to register late begins the first day of the quarter, January 5th!
• Instructor permission to register late ends the fifth day of the quarter, January 9th!

# DOSM 315Physics for Medical Dosimetry I• 5 Cr.

## Description:

Explores the fundamentals of radiation therapy physics with special attention to nuclear transformations and decay, x-ray production, radiation generators, interactions of ionizing radiation, x-ray beam quality, measurement of absorbed dose, dose distribution and scatter analysis. Prerequisite: Acceptance into the program.

## Outcomes:

After completing this class, students should be able to:

• Calculate the decay constant, mean and half-life of a radioactive source
• Identify internal structure of an x-ray tube and identify the two different mechanisms by which x-rays are produced.
• Identify key components and differential mechanisms between current linear accelerator technology and historical delivery units.
• Define the difference between transmission and geometric penumbra and be able to calculate geometric penumbra.
• Define the terms attenuation and linear attenuation coefficients and apply these terms to Half and Tenth Value Layers.
• Discuss the differences between coherent scattering, photoelectric effect, Compton effect, pair production and annihilation radiation and their associated energy ranges.
• Calculate the incident photon energy, scattered photon energy or scattered electron energy for Compton interaction.
• Describe the dependence of various interactionsâ€™ on atomic number
• Calculate equivalent attenuation using electron density across multiple mediums.
• Define the stem effect and the two root causes for this effect.
• Define the unit of measurement, the Roentgen, and its relationship to electronic equilibrium within a free-air ionization chamber.
• Calculate the temperature and pressure correction for exposure measurement
• Calculate the exposure in Roentgens for a field of radiation.
• Calculate the HVL for a radiation beam
• Discuss the limitations to HVL alone as a measure of beam quality in superficial and orthovoltage range units.
• Define the relationship between kerma, exposure and absorbed dose.
• Calculate dose to any medium using the f-factor and define the change in the f-factor as function of energy.
• Analyze the TG-21 and TG-51 recommendations for absorbed dose measurements and calibration.
• Calculate the dose to a prescribed depth using Percentage Depth Dose charts (PDD).
• Calculate the equivalent square for an irregular field size.
• Calculate the Tissue-Air Ratio (TAR) for a given clinical field size and depth.
• Define the relationship between the Backscatter Factor and TAR.
• Define the relationship between the TAR and PDD for a given beam.
• Calculate the Scatter-Air Ratio using TAR data.
• Define the Clarkson method of dose calculation for irregular fields.

v3.4.2.0