Commissioning of the Leksell Gamma Knife^® Icon™

Abstract

The LGK Icon was successfully commissioned for clinical use. The use of the EBT3 to characterize the treatment unit was demonstrated to be feasible. The CBCT imaging system operates well within the manufacturer's specifications and provides good geometrical accuracy.

Quality assurance tests for the Gamma Knife® Icon™ image guidance system

“…However, the uniformity was comparable using either of the two presets. Zeverino et al reported a similar spatial resolution (7 lp/cm) for both presets, and better image qualities for the high‐quality preset in terms of CNR: 1.2 vs 0.8 (high/low presets); and uniformity: 8.8% vs 9.3% (high/low presets) 2. Dorenlot and Champoudry used different software (MyQA, IBA Dosimetry, Schwarzenbruck, Germany) with the Catphan 503 phantom to evaluate the image qualities, and reported lower spatial resolution values than ours of 4.9 and 4.8 lp/cm (low/high presets); higher CNR values of 1.41 and 2.24 (low/high presets).…”

“…Our CTDI w dose measurements are within 10% of nominal values. Zeverino et al reported CTDI w values closer to nominal (2.41 and 6.32 mGy for low/high presets, respectively),2 while Dorenlot and Champoudry reported values similar to ours (2.23 and 5.9 mGy low/high presets, respectively) 10. According to the manufacturer, less than ±35% deviations from the nominal values of the Icon's x‐ray unit are expected, and the differences are dependent on the generator, tube output, and manufacturing of the unit covers 5.…”

“…For tracking intrafractional motions, the Icon comes with an Intra‐Fraction Motion Management (IFMM) system consisting of an infrared (IR) camera that tracks the movement of a reflective marker, typically placed on the patient's nose, with respect to reference reflective markers permanently attached to the head rest adapter during treatment delivery. The CBCT and IFMM system specifications were described in previous publications 1, 2…”

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

“…One report has published on the stability of the CBCT system over several months . Zeverino et al also published on Icon commissioning by focusing on a subset of tests mainly to do with relative output factor measurement, CBCT isocenter validation as well as some image quality testing . Wright et al looked at the HDMM portion of the Icon…”

“…10 Zeverino et al also published on Icon commissioning by focusing on a subset of tests mainly to do with relative output factor measurement, CBCT isocenter validation as well as some image quality testing. 11 Wright et al looked at the HDMM portion of the Icon. 12 The focus of the present work is to characterize the components specific to the Icon, including quantitative CBCT image analysis quality, mechanical characterization of the CBCT system, and complete closed loop testing.…”