Gynecologic oncology
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Gynecologic oncology · Feb 1996
Determination of the appropriate fraction number and size of the HDR brachytherapy for cervical cancer.
Based on the linear-quadratic model, we have made two isoeffect tables for transforming the traditional low dose rate (LDR) point A doses at 20, 30, 40, 50, 60, and 70 Gy to those of the high dose rate (HDR) dose per fraction. HDR fractions ranged from 1 to 12, with corresponding sizes for each fraction. We also propose the therapeutic gain ratio (TGR) method for determining the appropriate fraction number of HDR brachytherapy in cervical cancer. ⋯ The TGR is affected by many factors, such as the equivalent total dose of LDR, dose rate of LDR, HDR fraction number, T1/2, and differences between LDR and HDR in the dose in critical organs. The TGR method might explain why a low fraction number of HDR can be used in clinical practice. We may use this principle to replace the traditional trial-and-error method for transcribing the relationship between LDR and HDR treatments.