Quality assurance of stereotactic alignment and patient positioning mechanical accuracy for robotized Gamma Knife radiosurgery

Abstract

The automatic patient positioning system and its alignment is critical and specified to be less than 0.35 mm for a radiosurgical treatment with the latest robotized Gamma Knife Perfexion (GKPFX). In this study, we developed a quantitative QA procedure to verify the accuracy and robustness of such a system. In particular, we applied the test to a unit that has performed >1000 procedures at our institution. For the test, a radiochromic film was first placed inside a spherical film phantom and then irradiated with a sequence of linearly placed shots of equal collimator size (e.g. 4 mm) via the Leksell Gamma Knife Perfexion system (PFX). The shots were positioned with either equal or unequal gaps of approximately 8 mm both at center and off-center positions of the patient positioning system. Two independent methods of localizing the irradiation shot center coordinates were employed to measure the gap spacing between adjacent shots. The measured distance was then compared with the initial preset values for the test. On average, the positioning uncertainty for the PFX delivery system was found to be 0.03 ± 0.2 mm (2σ). No significant difference in the positioning uncertainty was noted among measurements in the x-, y- and z-axis orientations. In conclusion, a simple, fast, and quantitative test was developed and demonstrated for routine QA of the submillimeter PFX patient positioning system. This test also enables independent verification of any patient-specific shot positioning for a critical treatment such as a tumor in the brainstem.

Performance characterization of an integrated cone‐beam CT system for dedicated gamma radiosurgery

“…The reader can find many publications describing these in depth in literature. [4][5][6][7][8][9]11,13,17…”

Treatment-Plan Comparison of Three Advanced Radiation Treatment Modalities for Fractionated Stereotactic Radiotherapy to the Head and Neck

“…Overall, the mean target coverage across all patients was similar for the GKE, VMAT, and IMPT plans, with 98.9% ± 2.4% coverage (range 93.0% to 100%) for GKE, 99.4% ± 0.6% coverage (range 98.1% to 100.0%) for VMAT, and 96.8% ± 2.1% coverage (range 93.6% to 99.5%) for IMPT. However, for targets smaller than 15 cm 3 (Figure 4). However, this trend was not observed for GKE plans.…”

Stereotactic radiosurgery of glomus jugulare tumors: current concepts, recent advances and future perspectives

“…Feasibility and accuracy of using a relocatable frame system for fractionated Gamma knife radiosurgery was recently reported [74]. This approach may allow for treating larger GJT whilst exploiting the high mechanical accuracy of Gamma knife radiosurgery [75,76].…”