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Purpose: The ProTom Radiance 330 proton radiotherapy system is a fully functional, compact proton radiotherapy system that provides advanced proton delivery capabilities. It supports three-dimensional beam scanning with energy and intensity modulation. A series of measurements have been conducted to characterize the beam performance of the first installation of the system at the McLaren Proton Therapy Center in Flint, Michigan. These measurements were part of the technical commissioning of the system. Select measurements and results are presented. Methods: The Radiance 330 proton beam energy range is 70–250 MeV for treatment, and up to 330 MeV for proton tomography and radiography. Its 3-D scanning capability, together with a small beam emittance and momentum spread, provides a highly efficient beam delivery. During the technical commissioning, treatment plans were created to deliver uniform maps at various energies to perform Gamma Index analysis. EBT3 Gafchromic films were irradiated using the Planned irradiation maps. Bragg Peak chamber was used to test the dynamic range during a scan in one layer for high (250 MeV) and Low (70 MeV) energies. The maximum and minimum range, range adjustment and modulation, distal dose falloff (80%–20%), pencil beam spot size, spot placement accuracy were also measured. The accuracy testingmore » included acquiring images, image registration, receiving correction vectors and applying the corrections to the robotic patient positioner. Results: Gamma Index analysis of the Treatment Planning System (TPS) data vs. Measured data showed more than 90% of points within (3%, 3mm) for the maps created by the TPS. At Isocenter Beam Size (One sigma) < 3mm at highest energy (250 MeV) in air. Beam delivery was within 0.6 mm of the intended target at the entrance and the exit of the beam, through the phantom. Conclusion: The Radiance 330 Beam Performance Measurements have confirmed that the system operates as designed with excellent clinical performance specifications. Hovakim Nazaryan, Vahagn Nazaryan and Fuhua Wang are employees of ProTom International, Inc. who contributed to the development and completed the technical commissioning of the Radiance 330 proton therapy delivery system manufactured by ProTom International.« less

Purpose: Dose calibration protocols such as AAPM TG51 for photons and IAEA TR389 for protons recommend using specific KQ quality factor for different ionization chambers for absolute dosimtery in radiation therapy beams. However, there is no quality factor for Bragg Peak chambers (BPC) which are used for proton pencil beams. We have investigated a method to determine the KQ value for this chamber for proton pencil beam dose calibration.Method and Material: A uniform scanning proton beam from a cyclotron accelerator was used to irradiate a PTW‐BPC and an ADCL calibrated IBA‐PPC05 parallel plate chamber (PPC) to obtain the Nw × KQ factor for BPC. Distinctly, measurements of number of protons and the dose were measured simultaneously using the BPC, a Faraday cup, and EBT3 film dosimetry using a single proton pencil beam with a synchrotron accelerator. The calibration of film absolute dosimetry was assessed in a calibrated proton beam with a SOBP width of 10‐cm and range of 16‐cm. The Nw for BPC was determined using TG21 protocol against a PTW‐PPC in a high energy electron beam. Results: Our analysis indicates that KQ for BPC is equal to 1.08 with an uncertainty of ±1%. Independent measurements of the same chamber at different cyclotron proton center produced an agreement of 0.4% for Nw x KQ factor. However, the determination of Nw. KQ of different chamber using a synchrotron proton therapy center disagreed by 6%. The Nw obtained from TG21 protocol was in agreement with manufacturer value to within 0.2%. Conclusion: This investigation produced some results that suggest that there is a possible dose rate dependency of BPC in proton beams. This Result is currently under investigation, but it is believed that the KQ factor is not affected by this dependency.