ABSTRACT
Soil radon has been monitored at a fixed location on the northeastern flank of Mt. Etna, a high-risk volcano in Sicily. The aim of this study was to evaluate the effects of the recent volcanic activity on soil radon concentration. Continuous radon measurements have been performed since July 2001. While comparison between the trend in in-soil radon concentration and the acquired meteorological series (temperature, humidity and pressure) appear to confirm a general seasonal correlation, nevertheless particular anomalies suggest a possible dependence of the radon concentration on volcanic dynamics.
ABSTRACT
Due to their ballistic precision, apoptosis induction by protons could be a strategy to specifically eliminate neoplastic cells. To characterize the cellular and molecular effects of these hadrons, we performed dose-response and time-course experiments by exposing different cell lines (PC3, Ca301D, MCF7) to increasing doses of protons and examining them with FACS, RT-PCR, and electron spin resonance (ESR). Irradiation with a dose of 10 Gy of a 26,7 Mev proton beam altered cell structures such as membranes, caused DNA double strand breaks, and significantly increased intracellular levels of hydroxyl ions, are active oxygen species (ROS). This modified the transcriptome of irradiated cells, activated the mitochondrial (intrinsic) pathway of apoptosis, and resulted in cycle arrest at the G2/M boundary. The number of necrotic cells within the irradiated cell population did not significantly increase with respect to the controls. The effects of irradiation with 20 Gy were qualitatively as well as quantitatively similar, but exposure to 40 Gy caused massive necrosis. Similar experiments with photons demonstrated that they induce apoptosis in a significantly lower number of cells and in a temporally delayed manner. These data advance our knowledge on the cellular and molecular effects of proton irradiation and could be useful for improving current hadrontherapy protocols.
Subject(s)
Apoptosis/radiation effects , Neoplasms/radiotherapy , Proton Therapy , Apoptosis/genetics , Base Sequence , Cell Cycle/radiation effects , Cell Line, Tumor , DNA Damage , DNA Primers/genetics , Electron Spin Resonance Spectroscopy , Female , Flow Cytometry , Humans , Male , Necrosis , Neoplasms/genetics , Neoplasms/metabolism , Neoplasms/pathology , Photons/therapeutic use , RNA, Messenger/genetics , RNA, Neoplasm/genetics , Reactive Oxygen Species/metabolism , Reverse Transcriptase Polymerase Chain ReactionABSTRACT
The aim of this work was to investigate the use of TLD-100 detectors in the field of relative dosimetry in proton eye facilities. These dosemeters, of different sizes, were used to measure transverse and longitudinal distributions of 62 MeV unmodulated proton beams at INFN-LNS in Catania. Comparison with other detectors, such as ionisation chambers, GAF and radiographic film, is extensively discussed.
Subject(s)
Protons , Thermoluminescent Dosimetry/methods , Calibration , Reference Values , Reproducibility of ResultsABSTRACT
The dosimetric behaviour of a Scanditronix p-type silicon diode and a PTW natural diamond detector was studied in low-energy proton beams in the 8.3-21.5 MeV range. The properties investigated were linearity, reproducibility, dose rate dependence, energy and linear energy transfer (LET) dependence. The influence of detector thickness on the results of depth dose measurements was also demonstrated. A Markus parallel plate ionization chamber was used for reference dosimetry. Silicon diode and diamond detectors showed linearity at therapeutic dose level, reproducibility better than 1% (1sigma) and sensitivity variation with dose rate and proton energy.
