RadNuc: A graphical user interface to deliver dose rate patterns encountered in nuclear medicine with a ¹³⁷Cs irradiator

The temporal variations in absorbed dose rates to organs and tissues in the body are very large in diagnostic and therapeutic nuclear medicine. The response of biological endpoints of relevance to radiation safety and therapeutic efficacy is generally modulated by dose rate. Therefore, it is important to understand how the complex dose rate patterns encountered in nuclear medicine impact relevant biological responses. Accordingly, a graphical user interface (GUI) was created to control a cesium-137 irradiator to deliver such dose rate patterns. Methods: Visual Basic 6.0 was used to create a user-friendly GUI to control the dose rate by varying the thickness of a mercury attenuator. The GUI facilitates the delivery of a number of dose rate patterns including constant, exponential increase or decrease, and multi-component exponential. Extensive visual feedback is provided by the GUI during both the planning and delivery stages. Results: The GUI controlled irradiator can achieve a maximum dose rate of 40. cGy/h and a minimum dose rate of 0.01. cGy/h. Addition of machined lead blocks can be used to further reduce the minimum dose rate to 0.0001. cGy/h. Measured dose rate patterns differed from programmed dose rate patterns in total dose by 3.2% to 8.4%. Conclusion: The GUI controlled irradiator is able to accurately create dose rate patterns encountered in nuclear medicine and other related fields. This makes it an invaluable tool for studying the effects of chronic constant and variable low dose rates on biological tissues in the contexts of both radiation protection and clinical administration of internal radionuclides.