Dosimetry Calculations: Basic Monitor Unit Determination(1 credit hours)
Abstract
This module addresses the
quantities and calculations necessary for basic monitor unit (MU) measures used
in linear accelerator treatment applications. Related terms, concepts, and formulae
essential for any professional performing MU calculations are explained. The
module concludes with virtual patient exercises, using example-only data tables
to calculate relevant treatment values. Course Approval Expiration/End Date: December 1, 2010 Category A Credits
This activity may be available in multiple formats or from different sponsors. The ARRT does not allow CE activities such as internet courses, home study programs or directed readings to be repeated for CE credit in the same or any subsequent biennium.
Author
Gary Poteat, MS, DABR As a Senior Medical Physicist, Gary Poteat oversees treatment planning and monitor unit calculations on several thousand treatment fields every year. Gary has almost 30 years of experience in providing instruction in radiation safety and medical physics. He is a diplomat of the American Board of Radiology in Therapeutic Radiological Physics and a member of the American Association of Physicists in Medicine.
Objectives
Define the following terms:
Isocenter and SAD (Source-to-Axis Distance)
Central Axis of the Beam
Dose Maximum
Output
Target Dose
Prescription Depth
Field Size Correction Factor
Tissue-maximum Ratio
Equivalent Square Field Size
Irregular Fields
Inverse Square (Distance) Correction
Attenuation Factors
Off-Axis Factor
Isocenter
Accurately determine values required for basic monitor unit (MU) calculations
Correctly calculate monitor unit (MU) values for simple fields.
Resources
Khan, F: The Physics of
Radiation Therapy, ed.3. Baltimore, Williams and Wikins, 2003.
Johns, H and Cunningham, J; The Physics of Radiology, 4th edition, Springfield,
IL, Charles C. Thomas, 1983.
As a Senior Medical Physicist, Gary Poteat oversees treatment planning and monitor unit calculations on several thousand treatment fields every year. Gary has almost 30 years of experience in providing instruction in radiation safety and medical physics. He is a diplomat of the American Board of Radiology in Therapeutic Radiological Physics and a member of the American Association of Physicists in Medicine.