Publications by authors named "Giorgio Cucchi"

3 Publications

  • Page 1 of 1

How direct measurements on worker eyes with Scheimpflug camera can affect lens dose conversion coefficients in interventional radiology.

J Radiol Prot 2021 Apr 7. Epub 2021 Apr 7.

Industrial Engineering - Montecuccolino Laboratory, University of Bologna, Via dei Colli 16, 40136 Bologna, Italy, Bologna, BO, 40136, ITALY.

The Directive 2013/59/Euratom established a reduction of the occupational exposure limits to the lens. Since it is become crucial to estimate the lens absorbed dose, the individual variability of exposed worker's ocular conformations with respect to the data estimated with their personal dosimetry has been studied. The anterior eye conformation of 45 exposed workers was acquired with Scheimpflug imaging and classified according to eye vision conditions (emmetropia, myopia or hypermetropia). Three eye models were computed, with two lens reconstructions, and implemented in an interventional radiology scenario by using Monte Carlo (MC) code. The models were dosimetrically analysed simulating setup A, a theoretical monoenergetic and isotropic photon's source (10-150 keV) and setup B, a more realistic interventional conditions with an angiographic X-ray unit (50, 75, 100 kV-peak). Scheimpflug imaging provided an average anterior chamber depth of (6.4 ± 0.5) mm and a lens depth of (3.9 ± 0.3) mm, together with a reconstructed equatorial lens length of (7.1 - 10.1) mm. Using this data for model's reconstruction, the dose conversion coefficients (DCs) for all ocular structures were simulated. Regardless of the eye model used, DCs show a similar trend with radiation energy which highlights, for the same energy and setup used, no significant dependence on ocular morphology and worker's visual conditions. The maximum difference obtained does not exceed 1% for all eye models or structures analysed. Therefore, the individual variabilities of worker ocular anatomy do not require any additional correction compared to the personal dosimetry data measured with a dedicated lens dosimeter. To estimate the absorbed dose to the other eye structures, it is essential instead to know the spectrum of the source that has generated the irradiation since there are differences considering monoenergetic sources or more realistic angiographic units.
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April 2021

DNA damage in lens epithelial cells exposed to occupationally-relevant X-ray doses and role in cataract formation.

Sci Rep 2020 12 10;10(1):21693. Epub 2020 Dec 10.

Department of Medical Physics, St. Orsola-Malpighi University Hospital, Bologna, Italy.

The current framework of radiological protection of occupational exposed medical workers reduced the eye-lens equivalent dose limit from 150 to 20 mSv per year requiring an accurate dosimetric evaluation and an increase understanding of radiation induced effects on Lens cells considering the typical scenario of occupational exposed medical operators. Indeed, it is widely accepted that genomic damage of Lens epithelial cells (LEC) is a key mechanism of cataractogenesis. However, the relationship between apoptosis and cataractogenesis is still controversial. In this study biological and physical data are combined to improve the understanding of radiation induced effects on LEC. To characterize the occupational exposure of medical workers during angiographic procedures an INNOVA 4100 (General Electric Healthcare) equipment was used (scenario A). Additional experiments were conducted using a research tube (scenario B). For both scenarios, the frequencies of binucleated cells, micronuclei, p21-positive cells were assessed with different doses and dose rates. A Monte-Carlo study was conducted using a model for the photon generation with the X-ray tubes and with the Petri dishes considering the two different scenarios (A and B) to reproduce the experimental conditions and validate the irradiation setups to the cells. The simulation results have been tallied using the Monte Carlo code MCNP6. The spectral characteristics of the different X-ray beams have been estimated. All irradiated samples showed frequencies of micronuclei and p21-positive cells higher than the unirradiated controls. Differences in frequencies increased with the delivered dose measured with Gafchromic films XR-RV3. The spectrum incident on eye lens and Petri, as estimated with MCNP6, was in good agreement in the scenario A (confirming the experimental setup), while the mean energy spectrum was higher in the scenario B. Nevertheless, the response of LEC seemed mainly related to the measured absorbed dose. No effects on viability were detected. Our results support the hypothesis that apoptosis is not responsible for cataract induced by low doses of X-ray (i.e. 25 mGy) while the induction of transient p21 may interfere with the disassembly of the nuclear envelop in differentiating LEC, leading to cataract formation. Further studies are needed to better clarify the relationship we suggested between DNA damage, transient p21 induction and the inability of LEC enucleation.
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December 2020

Enhancing radiosensitivity of melanoma cells through very high dose rate pulses released by a plasma focus device.

PLoS One 2018 29;13(6):e0199312. Epub 2018 Jun 29.

University of Bologna, Department of Physics and Astronomy, Bologna, Italy.

Radiation therapy is a useful and standard tumor treatment strategy. Despite recent advances in delivery of ionizing radiation, survival rates for some cancer patients are still low because of recurrence and radioresistance. This is why many novel approaches have been explored to improve radiotherapy outcome. Some strategies are focused on enhancement of accuracy in ionizing radiation delivery and on the generation of greater radiation beams, for example with a higher dose rate. In the present study we proposed an in vitro research of the biological effects of very high dose rate beam on SK-Mel28 and A375, two radioresistant human melanoma cell lines. The beam was delivered by a pulsed plasma device, a "Mather type" Plasma Focus for medical applications. We hypothesized that this pulsed X-rays generator is significantly more effective to impair melanoma cells survival compared to conventional X-ray tube. Very high dose rate treatments were able to reduce clonogenic efficiency of SK-Mel28 and A375 more than the X-ray tube and to induce a greater, less easy-to-repair DNA double-strand breaks. Very little is known about biological consequences of such dose rate. Our characterization is preliminary but is the first step toward future clinical considerations.
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April 2019