Radiation research
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In 1898, the discovery of two new elements, polonium and radium, reawakened interest in the topic of uranic rays discovered 2 years before by H. Becquerel. Radioactivity, a name coined by Marie Curie, became a major research field for decades. ⋯ It is shown how a well-chosen quantitative method and a systematic approach combining physics and chemistry led to the discovery within less than 1 year. The special role of radium and the determination of its atomic weight by Marie Curie followed by her long-term program for accumulating pure radium salts are emphasized. The first woman with a full professorship at a French University, Marie Curie created and managed the Radium Institute.
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Tumor reoxygenation after irradiation may contribute to a tumor's response to subsequent doses of radiation. The timing of reoxygenation in RIF-1 murine tumors was determined using electron paramagnetic resonance (EPR) oximetry with intratumoral implantation of an oxygen-sensitive paramagnetic material (India ink) to monitor the pO2 in individual murine tumors before, during and after three different irradiation schemes. Radiation was given as a single 20-Gy dose or was split into two 10-Gy doses where the second dose of radiation was delivered at the minimum postirradiation tumor pO2 (24-h interval, hypoxic group) or where the second dose of radiation was delivered after reoxygenation had occurred (72-h interval, oxygenated group). ⋯ There were significantly longer tumor doubling times in the oxygenated compared to the hypoxic group, indicating that the measured changes in pO2 reflected changes in tumor radiosensitivity. A 24-h interval between doses resulted in a delay of reoxygenation in the tumors, while a 72-h interval resulted in a second cycle of hypoxia/reoxygenation. Our results suggest that repeated direct measurements of pO2 in tumors by EPR oximetry could be useful in timing radiation doses to achieve improved local control of tumors.