title: Evaluation of the deformation and corresponding dosimetric implications in prostate cancer treatment.
abstract: The cone-beam computed tomography (CBCT) imaging modality is an integral component of image-guided adaptive radiation therapy (IGART), which uses patient-specific dynamic/temporal information for potential treatment plan modification. In this study, an offline process for the integral component IGART framework has been implemented that consists of deformable image registration (DIR) and its validation, dose reconstruction, dose accumulation and dose verification. This study compares the differences between planned and estimated delivered doses under an IGART framework of five patients undergoing prostate cancer radiation therapy. The dose calculation accuracy on CBCT was verified by measurements made in a Rando pelvic phantom. The accuracy of DIR on patient image sets was evaluated in three ways: landmark matching with fiducial markers, visual image evaluation and unbalanced energy (UE); UE has been previously demonstrated to be a feasible method for the validation of DIR accuracy at a voxel level. The dose calculated on each CBCT image set was reconstructed and accumulated over all fractions to reflect the 'actual dose' delivered to the patient. The deformably accumulated (delivered) plans were then compared to the original (static) plans to evaluate tumor and normal tissue dose discrepancies. The results support the utility of adaptive planning, which can be used to fully elucidate the dosimetric impact based on the simulated delivered dose to achieve the desired tumor control and normal tissue sparing, which may be of particular importance in the context of hypofractionated radiotherapy regimens.
authors.affiliation: Department of Radiation Oncology, Henry Ford Health System, Detroit, MI 48202, USA. nwen1@hfhs.org
authors.forename: Ning
authors.initials: N
authors.lastname: Wen
authors.forename: Carri
authors.initials: C
authors.lastname: Glide-Hurst
authors.forename: Teamour
authors.initials: T
authors.lastname: Nurushev
authors.forename: Lei
authors.initials: L
authors.lastname: Xing
authors.forename: Jinkoo
authors.initials: J
authors.lastname: Kim
authors.forename: Hualiang
authors.initials: H
authors.lastname: Zhong
authors.forename: Dezhi
authors.initials: D
authors.lastname: Liu
authors.forename: Manju
authors.initials: M
authors.lastname: Liu
authors.forename: Jay
authors.initials: J
authors.lastname: Burmeister
authors.forename: Benjamin
authors.initials: B
authors.lastname: Movsas
authors.forename: Indrin J
authors.initials: IJ
authors.lastname: Chetty
mesh_terms: D000368:Aged; D002138:Calibration; D054893:Cone-Beam Computed Tomography; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D010388:Pelvis; D019047:Phantoms, Imaging; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D011874:Radiometry; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D061089:Radiotherapy, Image-Guided; D012189:Retrospective Studies