Determination of small field synthetic single-crystal diamond detector correction factors for CyberKnife, Leksell Gamma Knife Perfexion and linear accelerator. (December 2017)

• Record Type: Journal Article
• Authors: Veselsky, T.; Novotny, J.; Pastykova, V.; Koniarova, I.
• Is Part Of: Physica medica. Volume 44(2018)
• Page Start: 66
• Page End: 71
• Publication Date: 2017-12
• Subjects: Small field dosimetry -- Synthetic diamond detector -- Output factor -- Correction factor; Medical physics -- Periodicals; Biophysics -- Periodicals; Biophysics -- Periodicals; Imagerie médicale -- Périodiques; Radiothérapie -- Périodiques; Rayons X -- Sécurité -- Mesures -- Périodiques; Physique -- Périodiques; Médecine -- Périodiques; 610.153
• DOI: 10.1016/j.ejmp.2017.11.010
• Languages: English
• ISSNs: 1120-1797

Abstract

Highlights: Contradictions about MicroDiamond correction factors have been presented so far. MicroDiamond correction factors for CyberKnife are mostly within 1%. MicroDiamond correction factors for LGK Perfexion are within 2%. MicroDiamond correction factors for linear accelerator are mostly within 0.5%. MicroDiamond was found to be almost ideal tool for relative small field dosimetry. Abstract: Purpose: The aim of this study was to determine small field correction factors for a synthetic single-crystal diamond detector (PTW microDiamond) for routine use in clinical dosimetric measurements. Materials and methods: Correction factors following small field Alfonso formalism were calculated by comparison of PTW microDiamond measured ratio M Qclin fclin / M Qmsr fmsr with Monte Carlo (MC) based field output factors Ω Qclin, Qmsr fclin, fmsr determined using Dosimetry Diode E or with MC simulation itself. Diode measurements were used for the CyberKnife and Varian Clinac 2100C/D linear accelerator. PTW microDiamond correction factors for Leksell Gamma Knife (LGK) were derived using MC simulated reference values from the manufacturer. Results: PTW microDiamond correction factors for CyberKnife field sizes 25–5 mm were mostly smaller than 1% (except for 2.9% for 5 mm Iris field and 1.4% for 7.5 mm fixed cone field). The correction of 0.1% and 2.0% for 8 mm and 4 mm collimators, respectively, needed to be applied to PTW microDiamond measurements for LGK Perfexion. Finally, PTW microDiamond M Qclin fclin / M Qmsr fmsr for the linear accelerator varied from MC corrected Dosimetry Diode data by less than 0.5% (except for 1 × 1 cm 2 field size with 1.3% deviation). Conclusions: Regarding low resulting correction factor values, the PTW microDiamond detector may be considered an almost ideal tool for relative small field dosimetry in a large variety of stereotactic and radiosurgery treatment devices.