Characterization of the Medscint HYPERSCINT scintillation dosimetry research platform with orthovoltage photon beams and a novel quasi monoenergetic beam.

Abstract

Objective: This work aimed to evaluate the dosimetric characteristics of the new HyperScintTM Research Platform 200 system (HS-RP200), with orthovoltage beams and a novel kilovoltage converging beam, Converging Radiotherapy and Radiosurgery (CRnR) beam.

Approach: Several dosimetric properties of the HS-RP200 detector with several orthovoltage beams were studied in air. Relative dosimetry of the HS-RP200 detector was also studied for use on the converging x-ray beam. Energy correction factors were compared between measurement, Monte Carlo, and analytical methods.

Main results: The signal-to-noise ratio (SNR) for the detector increased as the frame exposure time increased, and repeated measurements had less uncertainty when measurements were performed without stem-effect removal (WOSER). The short-term stability study of the detector's signal showed an acceptable variance of its readings to within 1% during one-hour measurements. The detector exhibited angular independence within the measurement uncertainty of 1%. The detector exhibited excellent dose linearity response with the orthovoltage beams. During an 80-day period, repeated measurements determined that the detector possesses long-term stability within a root mean square (rms) of 2.3% and 0.6% when measurements were performed with stem effect removal (WSER) and WOSER, respectively. Calculated energy correction factors implied significant fluctuations of the HS-RP200 detector with the beam quality of orthovoltage beams, ranging from 3% to 66%, depending on the divergence of the effective energy of the beam from reference quality. Monte Carlo-simulated energy correction factors agreed with measurements with a maximum difference of 5.4% when measurements were performed WOSER. Lastly, the HS-RP200 detector system exhibited good relative dosimetric characteristics with the CRnR beam. A maximum rms value of 0.019 was calculated for the normalized profiles when measurements from the HS-RP200 detector were compared to measurements from film.

Significance: The HS-RP200 detector could be used as an alternative to other detectors with orthovoltage beams, including the CRnR beam.