Optimizing fiducial visibility on periodically acquired megavoltage and kilovoltage image pairs during prostate volumetric modulated arc therapy.

摘要: Purpose: Robust detection of implanted fiducials is essential for monitoring intrafractional motion during hypofractionated treatment. The authors developed a plan optimization strategy to ensure clear visibility and facilitate 3D localization volumetric modulated arc therapy (VMAT). Methods: Periodic kilovoltage (kV) images were acquired at 20° gantry intervals paired with simultaneously 4.4° short megavoltage digital tomosynthesis (MV-DTS) localize three VMAT delivery prostate cancer Beginning the original optimized plan, control point segments where consistently blocked by multileaf collimator(MLC) within each MV-DTS interval first identified. For segment, MLC apertures edited expose fiducial that led least increase in cost function. Subsequently, all points not involved visualization reoptimized compensate quality losses match dose–volume histogram. MV dose was also kept above 0.4 MU acceptable image quality. Different imaging (gantry) margins around evaluated. Results: Fiducials for, on average, 36% imagingcontrol five plans but properly exposed after reoptimization. Reoptimization resulted negligible dosimetric differences compared outperformed simple aperture editing: PTV D98 recovered from 87% 94% prescription, homogeneity improved 9% 7%. Without violating objectives compromising efficiency, highest frequency largest margin can be achieved are 10° interval, 15 mm, respectively. Conclusions: made accommodate MV-kV fiducials. Fiducial rate workflow efficiency significantly an automatic modification reoptimization approach.