Flexure dose: the low-dose limit of effective fractionation

Journal Article · Thu Sep 01 04:00:00 EDT 1983 · Int. J. Radiat. Oncol., Biol. Phys.; (United States)

DOI:https://doi.org/10.1016/0360-3016(83)90270-5· OSTI ID:5311806

Tucker, S L; Thames, Jr, H D

Total radiation dose often can be increased without subsequent increases in the severity of tissue injury by using reduced doses per fraction. The flexure dose, d/sub f/, is defined as the largest fractional dose for which further fractionation produces no significant change in the total dose required to reach a specified effect level. Thus, d/sub f/ is clinically relevant in that it represents the limit of effective dose fractionation. For those tissues in which injury reflects depletion of a critical proportion of target cells, the flexure dose is a measure of the extent of the initial, nearly linear portion of the dose-survival curve. More generally, the flexure dose is a measure of the extent of the initial, nearly linear portion of a dose-response curve in organized tissue, whatever its relationship to clonogenic target cells might be. Several quantitative expressions for d/sub f/ are derived. The characteristic common to these is that each defines the flexure dose as a multiple of the ratio ..cap alpha../..beta.. of the parameters of the linear-quadratic model of cell survival or dose response, where the multiple is a measure of experimental or statistical resolution. Estimates of the region of flexure are presented for a variety of normal and neoplastic tissues.

• Research Organization: Univ. of Texas, Houston
• OSTI ID: 5311806
• Journal Information: Int. J. Radiat. Oncol., Biol. Phys.; (United States), Journal Name: Int. J. Radiat. Oncol., Biol. Phys.; (United States) Vol. 9:9; ISSN IOBPD
• Country of Publication: United States
• Language: English

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62 RADIOLOGY AND NUCLEAR MEDICINE
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ANIMAL TISSUES
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
BIOLOGY
BODY
CALCULATION METHODS
DATA
DISEASES
DOSE-RESPONSE RELATIONSHIPS
DOSES
EXPERIMENTAL DATA
FRACTIONATED IRRADIATION
INFORMATION
IRRADIATION
LOW DOSE IRRADIATION
MEDICINE
NEOPLASMS
NUCLEAR MEDICINE
NUMERICAL DATA
RADIATION DOSES
RADIATION EFFECTS
RADIOBIOLOGY
RADIOLOGY
RADIOTHERAPY
THERAPY
TISSUES