On using the linear-quadratic model in daily clinical practice

Journal Article · Sat Jun 01 04:00:00 EDT 1991 · International Journal of Radiation Oncology, Biology and Physics; (United States)

DOI:https://doi.org/10.1016/0360-3016(91)90249-4· OSTI ID:5593340

Yaes, R J; Patel, P; Maruyama, Y ^[1]

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1. University of Kentucky Medical Center, Lexington (USA)

To facilitate its use in the clinic, Barendsen's formulation of the Linear-Quadratic (LQ) model is modified by expressing isoeffect doses in terms of the Standard Effective Dose, Ds, the isoeffective dose for the standard fractionation schedule of 2 Gy fractions given once per day, 5 days per week. For any arbitrary fractionation schedule, where total dose D is given in N fractions of size d in a total time T, the corresponding Standard Effective Dose, Ds, will be proportional to the total dose D and the proportionality constant will be called the Standard Relative Effectiveness, SRE, to distinguish it from Barendsen's Relative Effectiveness, RE. Thus, Ds = SRE.D. The constant SRE depends on the parameters of the fractionation schedule, and on the tumor or normal tissue being irradiated. For the simple LQ model with no time dependence, which is applicable to late reacting tissue, SRE = ((d + delta)/(2 + delta)), where d is the fraction size and delta = alpha/beta is the alpha/beta ratio for the tissue of interest, with both d and delta expressed in units of Gy. Application of this method to the Linear Quadratic model with a time dependence, the LQ + time model, and to low dose rate brachytherapy will be discussed. To clarify the method of calculation, and to demonstrate its simplicity, examples from the clinical literature will be used.

• OSTI ID: 5593340
• Journal Information: International Journal of Radiation Oncology, Biology and Physics; (United States), Journal Name: International Journal of Radiation Oncology, Biology and Physics; (United States) Vol. 20:6; ISSN IOBPD; ISSN 0360-3016
• Country of Publication: United States
• Language: English

Related Subjects

550603* -- Medicine-- External Radiation in Therapy-- (1980-)
62 RADIOLOGY AND NUCLEAR MEDICINE
CALCULATION METHODS
CENTRAL NERVOUS SYSTEM
DISEASES
DOSES
FRACTIONATED IRRADIATION
IRRADIATION
LOW DOSE IRRADIATION
MATHEMATICAL MODELS
MEDICINE
MYELITIS
NEOPLASMS
NERVOUS SYSTEM
NERVOUS SYSTEM DISEASES
NUCLEAR MEDICINE
RADIATION DOSES
RADIOLOGY
RADIOTHERAPY
RBE
SPINAL CORD
THERAPY
TIME DEPENDENCE