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Title: Long-term stability of the Leksell Gamma Knife{sup ®} Perfexion™ patient positioning system (PPS)

Abstract

Purpose: To assess the long-term mechanical stability and accuracy of the patient positioning system (PPS) of the Leksell Gamma Knife{sup ®} Perfexion™ (LGK PFX). Methods: The mechanical stability of the PPS of the LGK PFX was evaluated using measurements obtained between September 2007 and June 2011. Three methods were employed to measure the deviation of the coincidence of the radiological focus point (RFP) and the PPS calibration center point (CCP). In the first method, the onsite diode test tool with single diode detector was used together with the 4 mm collimator on a daily basis. In the second method, a service diode test tool with three diode detectors was used biannually at the time of the routine preventive maintenance. The test performed with the service diode test tool measured the deviations for all three collimators 4, 8, and 16 mm and also for three different positions of the PPS. The third method employed the conventional film pin-prick method. This test was performed annually for the 4 mm collimator at the time of the routine annual QA. To estimate the effect of the patient weight on the performance of the PPS, the focus precision tests were also conducted with varying weightsmore » on the PPS using a set of lead bricks. Results: The average deviations measured from the 641 daily focus precision tests were 0.1 ± 0.1, 0.0 ± 0.0, and 0.0 ± 0.0 mm, respectively, for the 4 mm collimator in the X (left/right of the patient), Y (anterior/posterior of the patient), and Z (superior/inferior of the patient) directions. The average of the total radial deviations as measured during ten semiannual measurements with the service diode test tool were 0.070 ± 0.029, 0.060 ± 0.022, and 0.103 ± 0.028 mm, respectively for the central, long, and short diodes for the 4 mm collimator. Similarly, the average total radial deviations measured during the semiannual measurements for the 4, 8, and 16 mm collimators and using the central diode were 0.070 ± 0.029, 0.097 ± 0.025, 0.159 ± 0.028 mm, respectively. The average values of the deviations as obtained from the five annual film pin-prick tests for the 4 mm collimator were 0.10 ± 0.06, 0.06 ± 0.09, and 0.03 ± 0.03 mm for the X, Y, Z stereotactic directions, respectively. Only a minor change was observed in the total radial deviations of the PPS as a function of the simulated patient weight up to 202 kg on the PPS. Conclusions: Excellent long-term mechanical stability and high accuracy was observed for the PPS of the LGK PFX. No PPS recalibration or any adjustment in the PPS was needed during the monitored period of time. Similarly, the weight on the PPS did not cause any significant disturbance in the performance of the PPS for up to 202 kg simulated patient weight.« less

Authors:
; ;  [1]
  1. Department of Radiation Oncology, Medical Physics Division, University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania 15213 (United States)
Publication Date:
OSTI Identifier:
22250965
Resource Type:
Journal Article
Journal Name:
Medical Physics
Additional Journal Information:
Journal Volume: 41; Journal Issue: 3; Other Information: (c) 2014 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0094-2405
Country of Publication:
United States
Language:
English
Subject:
61 RADIATION PROTECTION AND DOSIMETRY; ACCURACY; CALIBRATION; COLLIMATORS; PATIENTS; PERFORMANCE; POSITIONING; RADIATION MONITORS; SIMULATION

Citation Formats

Novotny, J., E-mail: josef.novotnyml@homolka.cz, Department of Medical Physics, Na Homolce Hospital, Prague 150 30, Institute of Biophysics and Informatics, First Faculty of Medicine, Charles University in Prague, Prague 120 00, Department of Dosimetry and Application of Ionizing Radiation, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Prague 115 19, Department of Radiation Oncology, University Hospital Motol, Prague 150 06, Bhatnagar, J. P., Xu, Y., and Huq, M. S. Long-term stability of the Leksell Gamma Knife{sup ®} Perfexion™ patient positioning system (PPS). United States: N. p., 2014. Web. doi:10.1118/1.4866225.
Novotny, J., E-mail: josef.novotnyml@homolka.cz, Department of Medical Physics, Na Homolce Hospital, Prague 150 30, Institute of Biophysics and Informatics, First Faculty of Medicine, Charles University in Prague, Prague 120 00, Department of Dosimetry and Application of Ionizing Radiation, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Prague 115 19, Department of Radiation Oncology, University Hospital Motol, Prague 150 06, Bhatnagar, J. P., Xu, Y., & Huq, M. S. Long-term stability of the Leksell Gamma Knife{sup ®} Perfexion™ patient positioning system (PPS). United States. https://doi.org/10.1118/1.4866225
Novotny, J., E-mail: josef.novotnyml@homolka.cz, Department of Medical Physics, Na Homolce Hospital, Prague 150 30, Institute of Biophysics and Informatics, First Faculty of Medicine, Charles University in Prague, Prague 120 00, Department of Dosimetry and Application of Ionizing Radiation, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Prague 115 19, Department of Radiation Oncology, University Hospital Motol, Prague 150 06, Bhatnagar, J. P., Xu, Y., and Huq, M. S. 2014. "Long-term stability of the Leksell Gamma Knife{sup ®} Perfexion™ patient positioning system (PPS)". United States. https://doi.org/10.1118/1.4866225.
@article{osti_22250965,
title = {Long-term stability of the Leksell Gamma Knife{sup ®} Perfexion™ patient positioning system (PPS)},
author = {Novotny, J., E-mail: josef.novotnyml@homolka.cz and Department of Medical Physics, Na Homolce Hospital, Prague 150 30 and Institute of Biophysics and Informatics, First Faculty of Medicine, Charles University in Prague, Prague 120 00 and Department of Dosimetry and Application of Ionizing Radiation, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Prague 115 19 and Department of Radiation Oncology, University Hospital Motol, Prague 150 06 and Bhatnagar, J. P. and Xu, Y. and Huq, M. S.},
abstractNote = {Purpose: To assess the long-term mechanical stability and accuracy of the patient positioning system (PPS) of the Leksell Gamma Knife{sup ®} Perfexion™ (LGK PFX). Methods: The mechanical stability of the PPS of the LGK PFX was evaluated using measurements obtained between September 2007 and June 2011. Three methods were employed to measure the deviation of the coincidence of the radiological focus point (RFP) and the PPS calibration center point (CCP). In the first method, the onsite diode test tool with single diode detector was used together with the 4 mm collimator on a daily basis. In the second method, a service diode test tool with three diode detectors was used biannually at the time of the routine preventive maintenance. The test performed with the service diode test tool measured the deviations for all three collimators 4, 8, and 16 mm and also for three different positions of the PPS. The third method employed the conventional film pin-prick method. This test was performed annually for the 4 mm collimator at the time of the routine annual QA. To estimate the effect of the patient weight on the performance of the PPS, the focus precision tests were also conducted with varying weights on the PPS using a set of lead bricks. Results: The average deviations measured from the 641 daily focus precision tests were 0.1 ± 0.1, 0.0 ± 0.0, and 0.0 ± 0.0 mm, respectively, for the 4 mm collimator in the X (left/right of the patient), Y (anterior/posterior of the patient), and Z (superior/inferior of the patient) directions. The average of the total radial deviations as measured during ten semiannual measurements with the service diode test tool were 0.070 ± 0.029, 0.060 ± 0.022, and 0.103 ± 0.028 mm, respectively for the central, long, and short diodes for the 4 mm collimator. Similarly, the average total radial deviations measured during the semiannual measurements for the 4, 8, and 16 mm collimators and using the central diode were 0.070 ± 0.029, 0.097 ± 0.025, 0.159 ± 0.028 mm, respectively. The average values of the deviations as obtained from the five annual film pin-prick tests for the 4 mm collimator were 0.10 ± 0.06, 0.06 ± 0.09, and 0.03 ± 0.03 mm for the X, Y, Z stereotactic directions, respectively. Only a minor change was observed in the total radial deviations of the PPS as a function of the simulated patient weight up to 202 kg on the PPS. Conclusions: Excellent long-term mechanical stability and high accuracy was observed for the PPS of the LGK PFX. No PPS recalibration or any adjustment in the PPS was needed during the monitored period of time. Similarly, the weight on the PPS did not cause any significant disturbance in the performance of the PPS for up to 202 kg simulated patient weight.},
doi = {10.1118/1.4866225},
url = {https://www.osti.gov/biblio/22250965}, journal = {Medical Physics},
issn = {0094-2405},
number = 3,
volume = 41,
place = {United States},
year = {Sat Mar 15 00:00:00 EDT 2014},
month = {Sat Mar 15 00:00:00 EDT 2014}
}