Search

(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. [ABSTRACT FROM AUTHOR]

Background: While computed tomography (CT) exams are the major cause of medical exposure to ionising radiation, the radiation-induced risks must be documented. We investigated the impact of the cellular models and individual factor on the deoxyribonucleic acid double-strand breaks (DSB) recognition and repair in human skin fibroblasts and brain astrocytes exposed to current head CT scan conditions. Method: Nine human primary fibroblasts and four human astrocyte cell lines with different levels of radiosensitivity/susceptibility were exposed to a standard head CT scan exam using adapted phantoms. Cells were exposed to a single-helical (37.4 mGy) and double-helical (37.4 mGy + 5 min + 37.4 mGy) examination. DSB signalling and repair was assessed through anti-γH2AX and anti-pATM immunofluorescence. Results: Head CT scan induced a significant number of γH2AX and pATM foci. The kinetics of both biomarkers were found strongly dependent on the individual factor. Particularly, in cells from radiosensitive/susceptible patients, DSB may be significantly less recognised and/or repaired, whatever the CT scan exposure conditions. Similar conclusions were reached with astrocytes. Conclusions: Our results highlight the importance of both individual and tissue factors in the recognition and repair of DSB after current head CT scan exams. Further investigations are needed to better define the radiosensitivity/susceptibility of individual humans. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract Purpose The aim of this work is to compare the energy response of a scintillating fiber to that of standard detectors used for dose monitoring in Computed Tomography (CT) and confirm the validity of Plastic Scintillating Detectors in CT dosimetry. We also seek to model the scintillating fiber response in realistic irradiation conditions for future applications on a complete dose measurement system. For this, we have modeled an X-ray generator emission and validated the model using its measured X-rays spectrum. Materials and methods Irradiations were performed in an X-ray generator at voltage varying from 80 to 140 kV. The Plastic Scintillating Detector (PSD) was compared with a pencil ion chamber and Thermo-Luminescent Detectors (TLD). Monte Carlo simulations of each detector response were compared to measurements in order to validate the simulation in a simple case. Results The Monte Carlo simulations reproduced accurately the response of each detector with less than 3% and 5% of difference for the ion chamber and the TLDs respectively. When comparing the PSD with the two standard detectors, we observed that while the plastic scintillator detector and the ion chamber responses presented less than 5% discrepancy, they both were very different than TLDs response on the whole investigated energy range. The Monte Carlo simulation of the PSD reproduced accurately the response of the plastic scintillating detector with less than 3% of difference. Conclusion The X-ray spectrum has been accurately measured which allowed to successfully reproduce the energy response of the PSD using Monte Carlo simulations. Although this study proved that the scintillating fibers energy response is appropriate for CT dose measurement, further experiments must be performed in clinical conditions. Highlights • This work is about the validation of a new dosimetry system based on scintillating fiber (PSD) for CT patient dosimetry. • A characterization of the PSD response was performed and compared to standards like ion chamber (IC) and TLD. • PSD was found to be suitable for dosimetry in CT range. • Monte Carlo (MC) simulations of PSD was validated. • MC could be used as reference to validate the scintillating detector for CT patient dosimetry in a further study. [ABSTRACT FROM AUTHOR]