A Feasible Real-time Multiplane MRI-LINAC Guidance Strategy

Abstract

distances (as measured from the simulation CT images). For the 25 postprostatectomy patients, the ranges of inter-fractional inter-transponderdistance variations were 0.34 cm (mean value, STD Z 0.28 cm; Range: 0.073 cm e 1.84 cm) and were 8.0% (mean value; STD Z 3.5%; Range: 4.1% e 60.6%) of the original distances. Using 0.5 cm and 20% as a cutoff, 16 out of the 25 post-prostatectomy patients had rigid transponder geometry, while the remainder 9 patients had deformable transponder geometry. There was no statically significant correlation between the distance from the transponders to the rectum, bladder or VUA and the deformable target geometry. Conclusion: The transponders implanted in a subset of the post-prostatectomy patients displayed significant amount of fiducial geometry deformation, indicating that the prostatic bed was not rigid for these patients. Further work needs to be done to evaluate the dosimetric effect of prostatic bed deformation on delivered dose. Author Disclosure: M. Zhu: None. W. Hou: None. H. Gay: None. J. Ge: None. J.M. Michalski: None. P.J. Parikh: E. Research Grant; Calypso, Varian, Philips. G. Consultant; Innovative Pulmonary Systems. J. Funding Other; Medical Litigation. K. Stock; Innovative Pulmonary Systems.