Image enhancement techniques allowing observation of intra-fractional motion in IMRT treatment for prostate carcinoma

Purpose: To estimate intrafracional motion of the prostate in a routine clinical setting during IMRT treatment and its impact on margin reduction and treatment time. Method and Materials: We outline the theory and algorithms needed to provide positional information from images obtained during IMRT treatment with dynamic sliding window techniques. The patients underwent a marker match procedure ensuring correct positioning at time of treatment. For all fields intra-treatment images were obtained, yielding 5 to 7 images per fraction. The images were processed using the proposed algorithm. The markers were detected in the image using an automated methodology. Results Application of this algorithm to 8 patients (960 images) yielded visible marker data for all images. For most fields starting parameters for the minimization routine needed to be determined manually. Starting parameters were identical within all images for a single beam direction for a given patient. For all of these patients time data was available and extracted. Conclusion: We have shown that it is possible with limited means to obtain relevant information on the position target volumes during treatment. The amount of data gathered is provides a wealth of free information without the need to setup complicated databases. © 2009 Springer-Verlag.