Individualized Fraction Regimen of SBRT Patients With Non-Small Cell Lung Cancer Based on Uncomplicated and Cancer-Free Control Probability

INTRODUCTION: Stereotactic body radiotherapy (SBRT) currently adopts non-discriminative prescription regimen. This study attempts to investigate an individualized fraction regimen (IFR) method for SBRT patients with non-small cell lung cancer (NSCLC) based on Uncomplicated and Cancer-free Control Probability (UCFCP). METHODS: Twenty patients with NSCLC were retrospectively prescribed with 40 regimens, ranging from 8Gy×5f to 12Gy×5f in step of 0.1 Gy. Taking into consideration of the age and the BMI index of each patient as well, the tumor control probability (TCP), the normal tissue complication probability (NTCP) of the total lung, chest wall and rib, and the secondary cancer probability (SCP) of the total lung were calculated for each plan of the patients. For the 40 regimens, the UCFCP was calculated and the maximum value of UCFCP was the IFR of the specified patient. Besides, IFR of UCP approach which only took account of the TCP and NTCP was also derived and to be compared with the IFR based on the UCFCP method. RESULTS: For all the patients, the UCFCP value showed a bell-shaped trend with the change of prescription dose. Among the 20 patients, the IFRs of 16 patients were different from the original fixed regimen. Of the 16 patients, the IFR of 5 patients exhibited slight changes between UCP and UCFCP methods. CONCLUSION: The method based on the maximum value of UCFCP function may be helpful to provide IFR for specific SBRT patients with NSCLC, differentiating the patient specific characteristics such as anatomical structures and locations.