Comparison of traditional and simultaneous IMRT boost technique basing on therapeutic gain calculation.
Two different radiotherapy techniques, a traditional one (CRT) - based on consecutive decreasing of irradiation fields during treatment, and intensity modulated radiation therapy technique (IMRT) with concomitant boost, deliver different doses to treated volumes, increasing the dose in regions of interest. The fractionation schedule differs depending on the applied technique of irradiation. The aim of this study was to compare different fractionation schedules considering tumor control and normal tissue complications. The analysis of tumor control probability (TCP) and normal tissue complication probability (NTCP) were based on the linear quadratic (LQ) model of biologically equivalent dose. A therapeutic gain (TG) formula that combines NTCP and TCP for selected irradiated volumes was introduced to compare CRT and simultaneous boost (SIB) methods. TG refers to the different doses per fraction, overall treatment time (OTT), and selected biological factors such as tumor cell and repopulation time. Therapeutic gain increases with the dose per fraction and reaches the maximum for the doses at about 3 Gy. Further increase in dose per fraction results in decrease of TG, mainly because of the escalation of NTCP. The presented TG formula allows the optimization of radiotherapy planning by comparing different treatment plans for individual patients and by selecting optimal fraction dose.
Slosarek
Krzysztof
K
Department of Radiotherapy and Brachytherapy Planning, and II Radiotherapy Clinic, Maria Sklodowska Curie Memorial Cancer Center and Institute of Oncology Gliwice Branch, Gliwice, Poland.
Zajusz
Aleksander
A
Szlag
Marta
M
D003661:Decision Support Techniques; D019583:Dose Fractionation, Radiation; D006258:Head and Neck Neoplasms / Q000532:radiotherapy; D006801:Humans; D008297:Male; D011471:Prostatic Neoplasms / Q000532:radiotherapy; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*