Evaluation of a synthetic single-crystal diamond detector for relative dosimetry on the Leksell Gamma Knife Perfexion radiosurgery system.
OBJECTIVE
To evaluate the new commercial PTW-60019 synthetic single-crystal microDiamond detector (PTW, Freiburg, Germany) for relative dosimetry measurements on a clinical Leksell Gamma Knife Perfexion radiosurgery system.


METHODS
Detector output ratios (DORs) for 4 and 8 mm beams were measured using a microDiamond (PTW-60019), a stereotactic unshielded diode [IBA stereotactic field detector (SFD)], a shielded diode (IBA photon field detector), and GafChromic EBT3 films. Both parallel and transversal acquisition directions were considered for PTW-60019 measurements. Measured DORs were compared to the new output factor reference values for Gamma Knife Perfexion (0.814 and 0.900 for 4 and 8 mm, respectively). Profiles in the three directions were also measured for the 4 mm beam to evaluate full width at half maximum (FWHM) and penumbra and to compare them with the corresponding Leksell GammaPlan profiles.


RESULTS
FWHM and penumbra for PTW-60019 differed from the calculated values by less than 0.2 and 0.3 mm, for the parallel and transversal acquisitions, respectively. GafChromic films showed FWHM and penumbra within 0.1 mm. The output ratio obtained with the PTW-60019 for the 4 mm field was 1.6% greater in transverse direction compared to the nominal value. Comparable differences up to 0.8% and 1.0% for, respectively, GafChromic films and SFD were found.


CONCLUSIONS
The microDiamond PTW-60019 is a suitable detector for commissioning and routine use of Gamma Knife with good agreement of both DORs and profiles in the three directions.
Physics Service of Radiation Oncology Department, Clinical and Research Center, Rozzano, Milan 20098, Italy.
Pietro
P
Mancosu
Physics Service of Radiation Oncology Department, Clinical and Research Center, Rozzano, Milan 20098, Italy.
Giacomo
G
Reggiori
Physics Service of Radiation Oncology Department, Clinical and Research Center, Rozzano, Milan 20098, Italy.
Antonella
A
Stravato
Physics Service of Radiation Oncology Department, Clinical and Research Center, Rozzano, Milan 20098, Italy.
Anna
A
Gaudino
Physics Service of Radiation Oncology Department, Clinical and Research Center, Rozzano, Milan 20098, Italy.
Francesca
F
Lobefalo
Physics Service of Radiation Oncology Department, Clinical and Research Center, Rozzano, Milan 20098, Italy.
Valentina
V
Palumbo
Radiation Oncology Department, Humanitas Clinical and Research Center, Rozzano, Milan 20089, Italy.
Piera
P
Navarria
Radiation Oncology Department, Humanitas Clinical and Research Center, Rozzano, Milan 20089, Italy.
Anna
A
Ascolese
Neurosurgery Department, Humanitas Clinical and Research Center, Rozzano, Milan 20089, Italy.
Piero
P
Picozzi
Dipartimento di Ingegneria Industriale, Università di Roma Tor Vergata, Roma 00133, Italy.
Marco
M
Marinelli
Dipartimento di Ingegneria Industriale, Università di Roma Tor Vergata, Roma 00133, Italy.
Gianluca
G
Verona-Rinati
Physics Service of Radiation Oncology Department, Clinical and Research Center, Rozzano, Milan 20098, Italy.
Stefano
S
Tomatis
Radiation Oncology Department, Humanitas Clinical and Research Center, Rozzano, Milan 20089, Italy.
Marta
M
Scorsetti
D018130:Diamond; D005373:Film Dosimetry / Q000295:instrumentation*; D016634:Radiosurgery; D035501:Uncertainty
D018130:Diamond