Characterisation of two new radiochromic gel dosimeters TruView (TM) and ClearView (TM) in combination with the vista (TM) optical CT scanner: A feasibility study

Purpose: This study aims at characterising the properties of TruView (TM) and ClearView (TM) two new gel dosimeters (Modus Medical Devices Inc.) and at studying the feasibility of relative dosimetry using these dosimeters and the Vista (TM) Optical CT scanner to accurately evaluate dose. Methods: In this work, we investigated key dosimetric aspects (dose response, energy and dose rate dependence) and stability of these radiochromic gels initiated in preliminary works (Huet et al., 2017; Colnot et al., 2017) using spectrophotometric measurements. Moreover, by mean of optical CT scanning (Vista (TM)), their performances to measure relative depth dose (PDD) and cross profiles were analysed. Results: TruView (TM) and ClearView (TM) present a linear dose response up to 20 Gy and up to 80 Gy respectively, independent of both photon beam energy (4-18 MV) and dose rate (up to 9.9 Gy/min) (Huet et al., 2017; Colnot et al., 2017). ClearView (TM) response proves to be stable for a week post-irradiation and uniform within the batch whereas TruView (TM) presents an unstable but uniform response. Optical CT scanning generates errors due to stray light that need to be corrected in order to use these gels; ClearView (TM) scanning particularly requires important precautions. After corrections, those gels used in combination with the Vista (TM) scanner show promising spatial and dosimetric precision (dose difference < 5%). Finally, TruView (TM) is reusable and presents excellent reproducible response (maximum 3% difference) and the ClearView (TM) dosimeter presents good spatial stability (0.5% difference after 6 days). Conclusion: This study provides important knowledge about two gel dosimeters presenting interesting dosimetric properties. A study is ongoing to benchmark those promising candidates for clinical dose verification.