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Dose response and stability of water equivalent PRESAGE <sup>?</sup> dosimeters for synchrotron radiation therapy dosimetry
摘要： This research investigated the dose response and post-irradiation stability of water-equivalent PRESAGE? dosimeters exposed to synchrotron radiation. Water-equivalent PRESAGE? dosimeters were irradiated up to 1000 Gy in a synchrotron x-ray beam with a mean energy of 95.3 keV. The change in optical density was measured using UV/visible spectrophotometry pre- and post-irradiation using a wavelength of 630 nm. Dose response was found to be approximately linear from 0–200 Gy with saturation occurring above 300 Gy. The post-irradiation stability was determined by measuring the change in optical density at 10, 30, 60, 180, 420 min and 7, 21 and 33 d post-irradiation for three groups of dosimeters stored at different temperatures. Each group had two dosimeters irradiated at 50, 100, 200 and 300 Gy and each group was stored at a different temperature following irradiation: room temperature (22 °C), 4 °C and ?18 °C. The optimal time for readout of the dosimeters varied with the post-irradiation storage temperature. The room temperature group had an optimal time-to-readout of 10 min for maximum signal before fading, while the 4 °C group was reasonably stable from 90 min to 1 week. The ?18 °C group showed the least amount of ongoing post-irradiation development and fading with an optimal readout window from 30 min to 21 d. The intra-batch variation between the mean of each temperature control group was 4.2% at 10 min post-irradiation.
关键词： PRESAGE? dosimeter,synchrotron radiation therapy,UV/Vis spectrophotometry
更新于2025-09-09 09:28:46
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Estimate of Nonuniformity of Dose Distribution in Regime of Total Therapeutic Irradiation with In Vivo Dosimetry Using Semiconductor Detectors
摘要： We have estimated the nonuniformity of the dose distribution along the body of a patient using in vivo dosimetry by semiconductor detectors with total therapeutic irradiation of cancer patients before bone marrow transplantation. The method of in vivo dosimetry was developed and used at the Blokhin Oncology Center since 2007. Based on the results of the investigation of 35 patients, we determined a mean nonuniformity of 10–15% of the dose distribution along the body of the patient, which conforms to international recommendations. We show a linear dependence of the accumulated dose on the mass of the patient.
关键词： total irradiation,in vivo dosimetry,semiconductor detectors,radiation therapy
更新于2025-09-04 15:30:14
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AN ALGORITHM TO DETERMINE THE NANODOSIMETRIC IMPACT OF GOLD NANOPARTICLES ON CELL MODELS
摘要： High-Z nanomaterials, e.g. gold nanoparticles (GNPs), are being investigated worldwide for potential application in radiation imaging and therapy. Photon irradiation of cells containing GNP was shown to produce enhanced DNA damage which is believed to be related to the increased secondary electron (SE) yield and ionization density. In this work, an algorithm was developed for simulating the physical radiation damage inside the nucleus of a spherical cell model for the case of uniformly distributed GNPs within the cytoplasm. Previously calculated energy spectra of SE emerging from a single NP irradiated with different photon sources are used as input to obtain the SE energy spectrum at the surface of the cell nucleus. In a second step, the SE transport inside the cell nucleus is simulated with a track structure Monte Carlo code to obtain the spatial distribution of ionizations. The preliminary results presented here show that the developed algorithm allows for a fast calculation of the SE spectra at the cell nucleus surface, thus enabling a more realistic assessment of the ionization density inside the cell nucleus than that obtained by the simulation of a single GNP. Furthermore, the algorithm can be easily adapted to investigate both the effect of GNP clustering and the impact of GNP–GNP interactions on SE spectra.
关键词： radiation therapy,secondary electrons,gold nanoparticles,Monte Carlo simulation,ionization density
更新于2025-09-04 15:30:14