Tracking the dose distribution in radiation therapy by accounting for variable anatomy.
The goal of this research is to calculate the daily and cumulative dose distribution received by the radiotherapy patient while accounting for variable anatomy, by tracking the dose distribution delivered to tissue elements (voxels) that move within the patient. Non-linear image registration techniques (i.e., thin-plate splines) are used along with a conventional treatment planning system to combine the dose distributions computed for each 3D computed tomography (CT) study taken during treatment. For a clinical prostate case, we demonstrate that there are significant localized dose differences due to systematic voxel motion in a single fraction as well as in 15 cumulative fractions. The largest positive dose differences in rectum, bladder and seminal vesicles were 29%, 2% and 24%, respectively, after the first fraction of radiation treatment compared to the planned dose. After 15 cumulative fractions, the largest positive dose differences in rectum, bladder and seminal vesicles were 23%, 32% and 18%, respectively, compared to the planned dose. A sensitivity analysis of control point placement is also presented. This method provides an important understanding of actual delivered doses and has the potential to provide quantitative information to use as a guide for adaptive radiation treatments.
Schaly
B
B
Radiation Treatment Program, London Regional Cancer Centre, 790 Commissioners Rd E, London, ON, N6A 4L6, Canada.
Kempe
J A
JA
Bauman
G S
GS
Battista
J J
JJ
Van Dyk
J
J
D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D015233:Models, Statistical; D019047:Phantoms, Imaging; D011467:Prostate / Q000528:radiation effects; D011471:Prostatic Neoplasms / Q000532:radiotherapy; D011874:Radiometry / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D020266:Radiotherapy, Conformal; D012680:Sensitivity and Specificity; D014018:Tissue Distribution; D014057:Tomography, X-Ray Computed / Q000379:methods*