Commissioning of a mobile electron accelerator for intraoperative radiotherapy

Abstract

Radiation performance characteristics of a dedicated intraoperative accelerator were determined to prepare the unit for clinical use. The linear accelerator uses standing wave X‐band technology (wavelength approximately 3 centimeters) in order to minimize the mass of the accelerator. The injector design, smaller accelerator components, and low electron beam currents minimize radiation leakage. The unit may be used in a standard operating room without additional shielding. The mass of the accelerator gantry is 1250 Kg (weight approximately 2750 lbs) and the unit is transportable between operating rooms. Nominal electron energies are 4, 6, 9, and 12 MeV, and operate at selectable dose rates of 2.5 or 10 Gray per minute. Dmax depths in water for a 10 cm applicator are 0.7, 1.3, 1.7, and 2.0 for these energies, respectively. The depths of 80% dose are 1.2, 2.1, 3.1, and 3.9 cm, respectively. Absolute calibration using the American Association of Physicists in Medicine TG‐51 protocol was performed for all electron energies using the 10 cm applicator. Applicator sizes ranged from 3 to 10 cm diameter for flat applicators, and 3 to 6 cm diameter for 30° beveled applicators. Output factors were determined for all energies relative to the 10 cm flat applicator. Central axis depth dose profiles and isodose plots were determined for every applicator and energy combination. A quality assurance protocol, performed each day before patient treatment, was developed for output and energy constancy.PACS number(s): 87.53.–j, 87.52.–g

Commissioning, clinical implementation, and performance of the Mobetron 2000 for intraoperative radiation therapy

“…The depth of d max , R 90 , and R 80 values are comparable to those published by Mills et al. for the Mobetron 1000, falling largely within 2 mm of the values reported there 15. The 12 MeV beam exhibits larger differences, up to 5 mm for R 80 .…”

“…Experience commissioning a previous model of the Mobetron, the Mobetron 1000, has been reported previously 15. However, in the time since that publication a new model has become commercially available, the Mobetron 2000.…”

Design and evaluation of electron beam energy degraders for breast boost irradiation

“…The PTW30013 Farmer type chamber (PTW, Freiburg, Germany) was used for this purpose. It was reported that the cylindrical PTW Farmer chamber and the parallel plate PTW Roos chamber agreed within 1 % for the 4 and 6 MeV energies, and within 0.5 % for the 9 and 12 MeV energies [ 42 ].…”

Dose distribution changes with shielding disc misalignments and wrong orientations in breast IOERT: a Monte Carlo – GEANT4 and experimental study

“…For this purpose, a new generation of mobile linear accelerators like NOVAC7 (NRT, Aprilia, Italy), (3) Liac (Sordina SpA, Italy), (4) and Mobetron (IntraOp Medical, Inc. Santa Clara, CA) (5) have been designed to deliver radiation therapy in the operating theater. A NOVAC7 system has been installed at our hospital to be used specifically for breast cancer treatment.…”