Normalization: what does it really mean?
Attempts have been made to standardize normalization techniques, but it remains a confusing issue. As of late there are five different possible normalization tools consisting of normalizing: 1. to the isocenter, 2. to a specific point other than the isocenter, 3. to a minimum target absorbed dose whose are of maximum target absorbed dose is a 2 cm2 area, 4. to an isodose value, 5. to the dmax of the beams. The International Commission on Radiation Units and Measurements has updated its report number 29 to further recommend normalization standards to include planning to a specification point that: 1. is easy to define in an unambiguous way, 2. is chosen in a region where the dose is rather homogeneous and representative of the dose distribution throughout the target volume, 3. defined where the dose can be accurately determined, 4. normalizes to the isocenter of the plan where the maximum absorbed dose is a 1.5 cm2 area, 5. limits the dose variation to 10%. With increasing complexity involving three-dimensional planning, mixed-beam therapy, and heterogeneity compensation, a full understanding of dose determination is necessary to accurately implement treatment plans.
Pickett
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B
Department of Radiation Oncology, University of California, San Francisco 94143-0226.
Altieri
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G
D006801:Humans; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods* / Q000592:standards