Highlights
- •First CyberKnife multicenter study on fixed cones and on Iris™ collimators.
- •MicroDiamond uncorrected vs MC corrected silicon diode output factors.
- •For CyberKnife output factor PTW60019 can be considered near “correction free”.
Abstract
Purpose
The aim of the present work was to evaluate small field size output factors (OFs)
using the latest diamond detector commercially available, PTW-60019 microDiamond,
over different CyberKnife systems. OFs were measured also by silicon detectors routinely
used by each center, considered as reference.
Methods
Five Italian CyberKnife centers performed OFs measurements for field sizes ranging
from 5 to 60 mm, defined by fixed circular collimators (5 centers) and by Iris™ variable aperture collimator (4 centers). Setup conditions were: 80 cm source to detector distance, and 1.5 cm depth in water. To speed up measurements two diamond detectors were used and their
equivalence was evaluated. MonteCarlo (MC) correction factors for silicon detectors
were used for comparing the OF measurements.
Results
Considering OFs values averaged over all centers, diamond data resulted lower than
uncorrected silicon diode ones. The agreement between diamond and MC corrected silicon
values was within 0.6% for all fixed circular collimators. Relative differences between
microDiamond and MC corrected silicon diodes data for Iris™ collimator were lower than 1.0% for all apertures in the totality of centers. The
two microDiamond detectors showed similar characteristics, in agreement with the technical
specifications.
Conclusions
Excellent agreement between microDiamond and MC corrected silicon diode detectors
OFs was obtained for both collimation systems fixed cones and Iris™, demonstrating the microDiamond could be a suitable detector for CyberKnife commissioning
and routine checks. These results obtained in five centers suggest that for CyberKnife
systems microDiamond can be used without corrections even at the smallest field size.
Keywords
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References
- The CyberKnife robotic radiosurgery system in 2010.Technol Cancer Res Treat. 2010; 9: 433-452
- Performance evaluation of a CyberKnife G4 image-guided robotic stereotactic radiosurgery system.Phys Med Biol. 2008; 53: 4697-4718
- Small field MV photon dosimetry.IPEM Report 103, York, UK2010
- Assessment of new small-field detectors against standard field detectors for practical stereotactic beam data acquisition.Phys Med Biol. 1999; 44: 2143-2160
- Dosimetric characterization of a bi-directional micromultileaf collimator for stereotactic applications.Med Phys. 2002; 29: 1456-1463
- The behavior of several microionization chambers in small intensity modulated radiotherapy fields.Med Phys. 2004; 31: 2792-2795
- Measurement of output factors for small photon beams.Med Phys. 2007; 34: 1983-1988
- Absorbed dose perturbation caused by diodes for small field photon dosimetry.Med Phys. 1994; 21: 1075-1079
- Comparative dosimetry in narrow high-energy photon beams.Phys Med Biol. 2000; 45: 685-693
- Report of AAPM TG 135: quality assurance for robotic radiosurgery.Med Phys. 2011; 38: 2914-2936
- CyberKnife dosimetric beam characteristics: comparison between experimental results and monte carlo simulation in robotic radiosurgery.CyberKnife Society Press, Sunnyvale, CA2005
- Small fields output factors measurements and correction factors determination for several detectors for a CyberKnife and linear accelerators equipped with microMLC and circular cones.Med Phys. 2013; 40: 071725
- Monte Carlo simulated correction factors for machine specific reference field dose calibration and output factor measurement using fixed and iris collimators on the CyberKnife system.Phys Med Biol. 2012; 57: 3741-3758
- A comparative study of small field total scatter factors and dose profiles using plastic scintillation detectors and other stereotactic dosimeters: the case of the CyberKnife.Med Phys. 2013; 40: 011719
- On the output factor measurements of the CyberKnife iris collimator small fields: experimental determination of the k fclin, fmsr Qclin, Qmsr correction factors for microchamber and diodes.Med Phys. 2012; 39: 4875-4885
- Determination of the k Q c l i n, Q m s r f c l i n, f m s r correction factors for detectors used with an 800 MU/min CyberKnife® system equipped with fixed collimators and a study of detector response to small photon beams using a Monte Carlo method.Med Phys. 2014; 41: 071702
- Variation of k Q clin, Q msr f clin, f msr for the small-field dosimetric parameters percentage depth dose, tissue-maximum ratio, and off-axis ratio.Med Phys. 2014; 41: 101708
- Dose rate dependence of a PTW diamond detector in the dosimetry of a 6MV photon beam.Phys Med Biol. 1994; 39: 1219-1229
- Evaluation of the dosimetric characteristics of a diamond detector for photon beam measurements.Med Phys. 1995; 22: 567-570
- Diamond detector versus silicon diode and ion chamber in photon beams of different energy and field size.Med Phys. 2003; 35: 2149-2154
- Design and characterization of a tissueequivalent CVD-diamond detector for clinical dosimetry in high-energy photon beams.Phys Med. 2008; 24: 159-168
- Clinical studies of optimized single crystal and polycrystalline diamonds for radiotherapy dosimetry.Radiat Meas. 2008; 43: 933-938
- A study of radiation dosimeters based on synthetic HPHT diamond.Diamond Relat Mater. 2007; 16: 191-195
- Dosimetric characterization of a synthetic single crystal diamond detector in clinical radiation therapy small photon beams.Med Phys. 2012; 39: 4493-4501
- Characterization of a synthetic single crystal diamond Schottky diode for radiotherapy electron beam dosimetry.Med Phys. 2013; 40: 021712-21719
- Clinical radiation therapy measurements with a new commercial synthetic single crystal diamond detector.J Appl Clin Med Phys. 2014; 25: 1-11
- Detector to detector corrections: a comprehensive experimental study of detector specific correction factors for beam output measurements for small radiotherapy beams.Med Phys. 2014; 41: 072103-72116
- On the correction, perturbation and modification of small field detectors in relative dosimetry.Phys Med Biol. 2014; 59: 5937-5952
- Properties of a commercial PTW-60019 synthetic diamond detector for the dosimetry of small radiotherapy beams.Phys Med Biol. 2015; 60: 905-924
- Synthetic single crystal diamond dosimeters for Intensity Modulated Radiation Therapy applications.Nucl Instrum Methods Phys Res A. 2009; 608: 191-194
- A synthetic diamond diode in volumetric modulated arc therapy dosimetry.Med Phys. 2013; 40: 092103
- Dosimetry of cone-defined stereotactic radiosurgery fields with a commercial synthetic diamond detector.Med Phys. 2014; 41: 111702
- Evaluation of the dosimetric properties of a synthetic single crystal diamond detector in high energy clinical proton beams.Med Phys. 2013; 40: 121702
- Dosimetric characterization of a microDiamond detector in clinical scanned carbon ion beams.Med Phys. 2015; 42: 2085-2093
- A synthetic diamond detector as transfer dosimeter for Dw measurements in photon beams with small field sizes.Metrologia. 2012; 49: S207-10
- Role of the technical aspects of hypofractionated radiation therapy treatment of prostate cancer: a review.Int J Radiat Oncol Biol Phys. 2015; 91: 182-195
- A feasibility dosimetric study on prostate cancer: are we ready for a multicenter clinical trial on SBRT?.Strahlenther Onkol. 2015; 191: 573-581
- Multicentre treatment planning inter-comparison in a national context: the liver stereotactic ablative radiotherapy case.Phys Med. 2016; 32: 277-283
- Multi-institutional application of failure mode and effects analysis (FMEA) to CyberKnife stereotactic body radiation therapy (SBRT).Radiat Oncol. 2015; 10: 132-137
- Evaluation of a synthetic single-crystal diamond detector for relative dosimetry measurements on a CyberKnife.Br J Radiol. 2014; 87: 20130768
- Chemical vapor deposition diamond based multilayered radiation detector: physical analysis of detection properties.J Appl Phys. 2010; 107: 014511-014517
- A new formalism for reference dosimetry of small and nonstandard fields.Med Phys. 2008; 35: 5179-5186
- Over-response of synthetic microDiamond detectors in small radiation fields.Phys Med Biol. 2014; 59: 5873-5881
- Application of the Exradin W1 scintillator to determine Ediode 60017 and microDiamond 60019 correction factors for relative dosimetry within small MV and FFF fields.Phys Med Biol. 2015; 60: 6669-6683
- Small field detector correction factors kQclin, Qmsrfclin, fmsr for silicon-diode and diamond detectors with circular 6 MV fields derived using both empirical and numerical methods.Med Phys. 2016; 43: 411-423
- The Radiological Physics Center’s standard dataset for small field size output factors.J Appl Clin Med Phys. 2012; 13: 282-289
Article info
Publication history
Published online: April 02, 2016
Accepted:
March 9,
2016
Received in revised form:
March 8,
2016
Received:
December 16,
2015
Identification
Copyright
© 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.
