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Nominal standard dose and tumor standard dose. Tables for radiation therapy planning and analysis
Abstract:
The method of treatment planning for a predetermined NSD value is described in detail using various example-problems. The Fret tables allow the finding of the total number of fractions needed (NT) for the NSD. This is done through the NSD/d ratio, d standing for the fractional dose in rad. The Fret tables are for 1 to 7 fractions-per-week treatment schedules. The corresponding value of T (elapsed days) are shown for different week days of the therapy initiation with their respective Fret and NSD/d values. The handling of the rest and multi-rest periods is described. A method of finding the NSD value for a treatment which has reached the maximum connective tissue tolerance is described, covering even the most complex treatment plans. Fret-tumor tables for NSD-tumor and their use are described by appropriate example-problems. Ret equivalent therapy planning through direct NSD methods (Fret tables) and through an approximation method (tables provided) is described and the usage demonstrated by example-problems. The usage of parallel opposing and multiple portals is evaluated in ret-dose values (peripheral radiobiologic effect) and certain conclusions drawn to guide the therapist. These show in which situations all portals per session should be used and when alternate portals are more beneficial. The effect of portal weighting is included in this analysis. The application of ELLIS' NSD method for radium therapy is described. If, in the future, any changes in the power factors of the present NSD formula become necessary, the basic handling of the NSD problems described in this manuscript will remain unchanged. The values obtained from these tables can then be adjusted by the appropriate factors.