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- Andersson, Charlotte, et al.
(författare)
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Diurnal variations in biodistribution of the radionuclide I-131 in mice
- 2016
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Ingår i: Swedish Cancer Research Meeting, Gothenburg, 2016, November 7-8.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Background: Radionuclides are routinely used to diagnose and treat many different types of cancer. I-131 is a well-established radioisotope used in e.g. treatment of thyroid cancer and neuroblastoma. Accurate knowledge of I-131 biodistribution is essential to correctly estimate the absorbed dose to normal organs and determine potential risks from I-131 exposure, which is especially important when treating children. Many biological functions in living organisms follow a circadian rhythm. Nevertheless, little is known about diurnal variations in radionuclide biodistribution. This study investigates if circadian rhythm affects I-131 biodistribution in mice and absorbed dose to organs and tissues. Materials & Methods: The radioactivity concentration in mice tissues was studied at different time-points after administration of I-131, and absorbed doses were calculated. The effect of circadian rhythm was studied by varying the time of administration. Results: Difference in activity concentration between the administration time-points was observed at many time-points after administration for most investigated tissues. For some organs differences were also observed in the absorbed dose. The highest activity concentration and absorbed dose were found in the thyroid regardless of time of administration. Conclusion: The results demonstrate that the biodistribution of I-131 in mice is influenced by the time of day of administration. These findings advocate that circadian rhythm should be considered in biodistribution studies and suggests that time-point of administration of radiopharmaceuticals containing I-131 for therapy can be further optimized. An optimized time-point could result in higher absorbed dose to the tumor and/or lower absorbed dose to normal tissues.
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- Andersson, Charlotte, et al.
(författare)
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The influence of circadian rhythm on the biodistribution of I-131
- 2016
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Ingår i: Swedish Radiation Research Association for Young Scientists Workshop, Stockholm, 2016, August 25-26.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Background: I-131 is well-established in nuclear medicine. The thyroid is a target organ when treating thyroid cancer with unbound I-131, but also a risk organ in I-131-based radionuclide therapy. Exposure to I-131 can also occur from the environment at nuclear accidents. Accurate knowledge of I-131 biodistribution is essential to correctly estimate the absorbed dose to organs and determine potential risks from both medical and hazard exposure. Many biological functions follow a circadian rhythm. Nevertheless, circadian rhythm remains an unknown factor in radionuclide biodistribution. Aim: The purpose of this study was to investigate if circadian rhythm affects I-131 biodistribution in mice and hence absorbed dose to mouse tissues. Methods: The radioactivity concentration in various tissues was studied at different time points after administration of I-131 and absorbed doses were calculated according to the MIRD formalism. The effect of circadian rhythm was studied by varying the time of administration. Male C57BL/6N mice were i.v. injected with I-131 at 8 am, 12 pm or 4 pm and killed after 1h to 7d. Results: Statistically significant difference in activity concentration and absorbed dose between the three injection series was observed for at least one time point after injection for many tissues. Highest activity concentration and absorbed dose were found in the thyroid. Conclusion: The results demonstrated that the biodistribution of I-131 in mice is influenced by the time of day of administration to a certain extent. These findings advocate that circadian rhythm should be considered in biodistribution studies and dose calculations.
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- Elvborn, Mikael, et al.
(författare)
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Sex-dependence in absorbed dose from I-131 in mice
- 2016
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Ingår i: Höstmöte med Cancerfondens Planeringsgrupp för Onkologisk Radionuklidterapi, Uppsala, 2016, November 24-25.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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