2D/3D Image fusion for accurate target localization and evaluation of a mask based stereotactic system in fractionated stereotactic radiotherapy of cranial lesions
(a) Illustration of the configuration of the Novalis x-ray system, and the transformation of the deviation measured in two x-ray images into the deviation in the patient coordinate system. (b) Detail in the imaging plane.
Two verification x-ray images for evaluation of deviation between the x-ray isocenter (cross) and the planned isocenter (center of the BB). (a) Image 1, (b) Image 2, (c) amplification of the cross and the BB of Image 1, (d) amplification of the cross and the BB of Image 2.
Two MV portal films for evaluation of deviation between the linac isocenter (center of the irradiated portal) and the planned isocenter (center of the BB). (a) AP film, (b) lateral film.
Evaluation of the patient positioning accuracy by comparing the bony structure in the x-ray image with that in the corresponding DRR using the spy glass. (a) x-ray image, (b) corresponding DRR, (c) spy glass check of matching before 6D fusion, (d) spy glass check of matching after 6D fusion. The arrows in figures (c) and (d) show the difference of anatomic matching before and after fusion.
Evaluation of the patient positioning accuracy by comparing the bony structures in the MV portal images and the corresponding DRR. (a) AP DRR, (b) AP portal image.
Positioning differences between the mask system and the 6D fusion method for the total of 127 fractions in 12 patients. (a) Differences in lateral vs longitudinal directions, (b) differences in AP vs longitudinal directions.
The overall position difference between the 3D and 6D fusion methods vs the total rotational angle for 127 fractions.
Statistic results of the target localization accuracy (mean values and standard deviations) of the “6D fusion” image guided system evaluated by kV x rays and MV portal films for eight planning isocenters in an anthropomorphic phantom.
Statistical results of the target localization accuracy and rotational variation of the “6D fusion” image guided system for various initial setup positions in two planning isocenters in an anthropomorphic phantom. The axis , and represent the lateral, longitudinal and PA directions. The angles , and represent the rotational angles around the , , and axis.
Evaluation of the anatomic landmark matches for the kV x-ray images and MV images for 127 treatment fractions in 12 patients—summary of the number of pairs of images according to different evaluation parameters.
The position variations of the mask system in three translational directions and three rotational directions for each patient, and overall uncertainty and reproducibility for all patients measured by the 6D fusion method. The reproducibility was defined as the setup error subtracting the mean setup error of a patient.
Summary of the localization uncertainty for different techniques reported in the literature.
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