US EPA

4966543 

Journal Article 

Design and performance characteristics of an experimental cesium-137 irradiator to simulate internal radionuclide dose rate patterns 

Howell, RW; Goddu, SM; Rao, DV 

1997 

Yes 

Journal of Nuclear Medicine
ISSN: 0161-5505
EISSN: 1535-5667 

38 

5 

727-731 

English 

9170437 

WOS:A1997WX89600023 

When radionuclides are administered internally, the biological effect can depend on the total absorbed dose and the rate at which it is delivered. A Cs-137 irradiator was designed to deliver dose-rate patterns that simulate those encountered in radionuclide therapy. Methods: An 18-Ci Cs-137 irradiator was fitted with a computer-controlled mercury attenuator that facilitated changes in dose rates as desired, The absorbed dose and dose rates were calibrated with MOSFET dosimeters customized for low dose-rates. Results: Initial dose rates ranging from 0.01-30 cGy/hr can be delivered depending on the location of the cage in the irradiator and the thickness of the mercury in the attenuator system. To demonstrate the irradiator system's capability to deliver dose-rate patterns encountered in radionuclide therapy, a simulation was performed where the dose rate initially increased exponentially followed by an exponential decrease in the dose rate, Conclusion: The irradiator system is well-suited to expose small animals to any dose-rate pattern, thereby facilitating calibration of biological dosimeters (e.g., cell survival, chromosome aberrations), which can be used to measure the absorbed dose-to a target tissue after administration of radionuclides. 

variable dose rate irradiator; mercury attenuator; biological dosimetry; cesium-137