Calibration of helical tomotherapy machine using EPR/alanine dosimetry

Abstract

Beam dose rate estimation results were found to be in good agreement with the reference value given by the manufacturer at 2% standard uncertainty. Moreover, the dose determination method was set up with a deviation around 2% (at a 2% standard uncertainty).

Reference dosimetry for helical tomotherapy: Practical implementation and a multicenter validation

“…As the static beam output was measured in a rectangular solid phantom (except at the Antwerp site), the presence of Virtual Water TM in the "dose to water" derivation in the msrf was studied with MC calculations: at the isocenter placed at 10 cm depth, the use of Virtual Water TM accounts for a factor D w, in SolidWater =D w, in water ¼ 0.995 6 0.003 (1 SD) which contradicts conclusions reported elsewhere. 33 The effect of using a (curved) cylindrical phantom of 10 cm radius accounts for a factor D cyl ph =D rect ph ¼ 0.9975 6 0.003 (1 SD) at the isocenter. Regarding the pcsrf delivery (test C), the measured dose was into accordance with the planned dose D meas =D TPS ¼ 1.002 6 0.015 (1 SD), irrespectively of the beam slit used and contrary to results reported earlier.…”

“…Regarding the pcsrf delivery (test C), the measured dose was into accordance with the planned dose D meas =D TPS ¼ 1.002 6 0.015 (1 SD), irrespectively of the beam slit used and contrary to results reported earlier. 33 The measurements in Table IV monitor the momentary beam output at each center and its stability is of concern. During a measurement session (short time) in Antwerp, the beam output was found stable within 0.3%; all measurements for a given center were performed within about 2.5 h and, under normal operation, important deviations during this time lapse are not expected, as the measurements in Table IV indicate.…”

Absolute calibration of the Gamma Knife® Perfexion™ and delivered dose verification using EPR/alanine dosimetry

“…LNHB alanine calibration curves had been validated as suitable for use of alanine in nonreference conditions. 12 Uncertainties are calculated for k = 1, using the following expression: 20…”

“…[7][8][9][10] Moreover, the LNHB has already carried out such studies for innovative radiotherapy techniques like Cyberknife or Tomotherapy. 11,12 Thanks to the shape and dimensions of alanine dosimeters, they can be used for small beams. Alanine dosimeters have interesting advantages: measures are at solid state and nondestructive, their responses are almost independent on the dose rate and energy of radiotherapy photon beams and their signal is stable in time (signal decreases less than 1% per year).…”

Correction factors for A1SL ionization chamber dosimetry in TomoTherapy: Machine‐specific, plan‐class, and clinical fields

“…Correction factors were obtained by comparing A1SL measurements with alanine dosimetry, provided by the National Physical Laboratory, NPL, and traceable to primary standards, through a postal dosimetry service already used for absolute dosimetry in TomoTherapy. [4][5][6] Finally, the applicability of the new formalism to clinical treatments was investigated with two clinical examples.…”