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Machines with Radionuclide Sources
Published in W. P. M. Mayles, A. E. Nahum, J.-C. Rosenwald, Handbook of Radiotherapy Physics, 2021
John Saunders, Lee Walton, Katharine Hunt
Cobalt-60 is manufactured by irradiating cobalt-59 in a high-neutron-flux nuclear reactor. The main reasons for its suitability for teletherapy are the availability of relatively small, high-specific-activity sources that minimise the beam penumbra; its relatively long half-life (5.27 years); and the almost monochromatic high-energy photon emission (photons of 1.173 MeV and 1.333 MeV in equal quantity).
ExperimentaL Oral Medicine
Published in Samuel Dreizen, Barnet M. Levy, Handbook of Experimental Stomatology, 2020
Samuel Dreizen, Barnet M. Levy
The effects of high doses of cobalt60 irradiation on rhesus monkey mandible was examined with light microscopy by Rohrer et al.104 Eight Macaca mullata monkeys, ranging in weight from 5.8 to 13.8 kg and in age from 1 to 10 years, were divided into control and test groups. Six were irradiated with cobalt60 in fractionated doses of 450 R per day split bilaterally over a 12-day period for a total of 4500 R. The irradiation was similar in amount and method of delivery to that given human patients with cancer. The observation period ranged from 1 week to 6 months postirradiation.
Radiation Therapy and Radiation Safety in Medicine
Published in Suzanne Amador Kane, Boris A. Gelman, Introduction to Physics in Modern Medicine, 2020
Suzanne Amador Kane, Boris A. Gelman
IMRT's rapid implementation does have its detractors, who argue that the adoption of this technology has been driven by hospitals competing for patients and higher insurance reimbursements, ahead of clinical studies of its effectiveness.* Others worry that because IMRT uses a higher intensity that it also can entail a greater radiation risk without proven benefits. It is hoped that ongoing clinical trials of IMRT will address these critiques. One of the challenges is the radiation dose and beam-range uncertainty, which is due to the uncontrolled motion of internal organs caused in part by breathing, digestion and heartbeats. The research to evaluate and reduce the impact of such effects is ongoing (Uchinami, Y. et al., “Impact of organ motion on volumetric and dosimetric parameters in stomach lymphomas treated with intensity-modulated radiotherapy” J. Appl. Clin. Med. Phys., Vol. 20, 2019, pp. 78–86.). The high expense of any accelerator-based technique leads to radioactive cobalt-60 sources being more practical for radiation therapy in the developing world.
A comprehensive review on recent nanosystems for enhancing antifungal activity of fenticonazole nitrate from different routes of administration
Published in Drug Delivery, 2023
Sadek Ahmed, Maha M. Amin, Sinar Sayed
This test is performed to ensure the ability of nanosystem to preserve its physical properties, measured responses and release profile following the sterilization process by gamma radiations. Gamma sterilization was performed in presence of dry ice to prevent any undesirable consequences. Cobalt-60 irradiator at rate of 1.774 kGy/h was employed with a radiation dose of 25 kGy in an Indian Gamma cell (Ahmed et al., 2022). Afterward, the resulted formulae were compared to the freshly prepared optimum formulae as previously discussed under effect of storage. Sterilization is important to eradicate any microbial contamination that could infect the body tissue especially the eye (Sayed et al., 2020). This test was performed for O-NV and O-OLN and both of them verified the absence of aggregates, unchanged responses (p > 0.05) and similar release profiles (ƒ2 > 50) (Ahmed et al., 2022a,b).
Comparing Iridium-192 with Cobalt-60 sources in high-dose-rate brachytherapy boost for localized prostate cancer
Published in Acta Oncologica, 2022
Jörg Tamihardja, Stefan Weick, Paul Lutyj, Marcus Zimmermann, Klaus Bratengeier, Michael Flentje, Bülent Polat
High-dose-rate brachytherapy (HDR-BT) in combination with external beam radiotherapy (EBRT) is an established treatment option for localized prostate cancer. Due to the small size of the sources, Iridium-192 (Ir-192) is often preferentially utilized in interstitial HDR-BT. Since Cobalt-60 (Co-60) sources with identical dimensions to those of Ir-192 have been made available, its physical properties make the radionuclide Co-60 an interesting alternative in clinical brachytherapy [1–3]. Co-60 has a longer half-life compared to Ir-192 with 63.3 months versus 2.4 months leading to a reduced number of source exchanges and therefore a significant cost reduction. As a tradeoff, Co-60 has a higher mean energy with 1.25 MeV compared to 0.37 MeV for Ir-192 resulting in the need for increased machine and room shielding. Moreover, Co-60 has a lower equivalent dose rate in air by a factor of 2.8 resulting in increased treatment times and the higher mean energy of Co-60 raises the concern about possible increased toxicity compared to patients treated with Ir-192. Therefore, in this current publication, the long-term oncological outcome, gastrointestinal (GI) and genitourinary (GU) toxicity, and dosimetric properties of two large real-life cohorts of prostate cancer patients treated with Ir-192 or Co-60 HDR-BT boost are compared.
Effects of the Cobalt-60 gamma radiation on Pichia pastoris glyceraldehyde-3-phosphate dehydrogenase
Published in International Journal of Radiation Biology, 2022
Abdelghani Iddar, Mohammed El Mzibri, Adnane Moutaouakkil
For the study of the in vitro effects of irradiation on the native purified GAPDH from P. pastoris, the purified protein from normal P. pastoris was dialyzed against 10 mM Tris–HCl buffer, pH 7.5, containing 1 mM EDTA, diluted at 2 mmol in 25 mM sodium phosphate buffer, pH 7.5 and then exposed to the dose of 2 Gy. After this, residual GAPDH activity was measured and compared to the purified enzyme activity treated at the same without radiation exposure. A decrease in the activity of the enzyme was observed after irradiation (Table 2) and 52.3 ± 1.2 U/mg of protein for the no-irradiated GAPDH became 46.7 ± 1.5 U/mg of protein for the irradiated enzyme. The effect of the in vitro Cobalt-60 irradiation on kinetic parameters of the enzyme was also investigated (Table 2). No significant change was observed in Km values of both d-G3P and NAD+, but a small decrease of the Vmax was noted for the irradiated enzyme (53.1 ± 1.9 µmol/min/mg of protein) compared to the normal enzyme (60.5 ± 2.4 µmol/min/mg of protein). It should be noted that below the dose of 1.5 Gy, no effect on GAPDH activity and on kinetic parameters has been detected (data not shown) and at 5 Gy, the dose-dependent inhibition of the enzyme was observed (25–30% loss of Vmax was observed at 5 Gy).