Background While computed tomography (CT) exams are the major cause of medical exposure to ionising radiation, there is increasing evidence that the potential radiation-induced risks must be documented. We investigated the impact of cellular models and individual factor on the deoxyribonucleic acid double-strand breaks (DSB) recognition and repair in human fibroblasts and mammary epithelial cells exposed to current chest CT scan conditions. Method Twelve human primary fibroblasts and four primary human mammary epithelial cell lines with different levels of radiosensitivity/susceptibility were exposed to a standard chest CT scan exam using adapted phantoms. Cells were exposed to a single helical irradiation (14.4 mGy) or to a topogram followed, after 1 min, by one single helical examination (1.1 mGy + 14.4 mGy). DSB signalling and repair was assessed through anti-γH2AX and anti-pATM immunofluorescence. Results Chest CT scan induced a significant number of γH2AX and pATM foci. The kinetics of both biomarkers were found strongly dependent on the individual factor. The topogram may also influence the biological response of radiosensitive/susceptible fibroblasts to irradiation. Altogether, our findings show that a chest CT scan exam may result in 2 to 3 times more unrepaired DSB in cells from radiosensitive/susceptible patients. Conclusions Both individual and tissue factors in the recognition and repair of DSB after current CT scan exams are important. Further investigations are needed to better define the radiosensitivity/susceptibility of individual humans.
(1) Background: The IVIscan is a commercially available scintillating fiber detector designed for quality assurance and in vivo dosimetry in computed tomography (CT). In this work, we investigated the performance of the IVIscan scintillator and associated method in a wide range of beam width from three CT manufacturers and compared it to a CT chamber designed for Computed Tomography Dose Index (CTDI) measurements. (2) Methods: We measured weighted CTDI (CTDIw) with each detector in accordance with the requirements of regulatory tests and international recommendations for the minimum, maximum and the most used beam width in clinic and investigated the accuracy of the IVIscan system based on the assessment of the CTDIw deviation from the CT chamber. We also investigated the IVIscan accuracy for the whole range of the CT scans kV. (3) Results: We found excellent agreement between the IVIscan scintillator and the CT chamber for the whole range of beam widths and kV, especially for wide beams used on recent technology of CT scans. (4) Conclusions: These findings highlight that the IVIscan scintillator is a relevant detector for CT radiation dose assessments, and the method associated with calculating the CTDIw saves a significant amount of time and effort when performing tests, especially with regard to new CT technologies.
For technical and radioprotection reasons, it has become essential to develop new dosimetric tools adapted to the specificities of computed tomography (CT) to ensure precise and efficient dosimetry since the current standards are not suitable for clinical use and for new CT technological evolution. Thanks to its many advantages, plastic scintillating fibers (PSF) is a good candidate for more accurate and personalized real-time dosimetry in computed tomography, and the company Fibermetrix has developed a new device named IVISCAN® based on this technology. In this study, we evaluated performances of IVISCAN® and associated uncertainties in terms of dose-rate dependence, angular dependence, stability with cumulative dose, repeatability, energy dependence, length dependence, and special uniformity in reference and clinical computed tomography beam qualities. For repeatability, the standard deviation is less than 0.039%, and the absolute uncertainty of repeatability lies between 0.017% and 0.025%. The deviation between IVISCAN® and the reference regarding energy dependence is less than 1.88% in clinical use. Dose rate dependence results show a maximum deviation under ±2%. Angular dependence standard deviation σ is 0.8%, and the absolute uncertainty was 1.6%. We observed 1% of variation every 50 Gy steps up to a cumulative dose of 500 Gy. Probe response was found to be independent of the PSF length with a maximum deviation < 2.7% between the IVISCAN® probe and the 1 cm PSF probe. The presented results demonstrated that IVISCAN® performances are in accordance with metrology references and the international standard IEC61674 relative to dosemeters used in X-ray diagnostic imaging and then make it an ideal candidate for real-time dosimetry in CT applications.
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