Since 2021 is the year mentioned, I need to confirm if MIRD237 2021 is a specific report, a conference, or a guideline. I'm not very familiar with the exact details, so I'll start by researching MIRD and its publications. The Medical Internal Radiation Dose Committee under the Society of Nuclear Medicine and Molecular Imaging (SNMMI) publishes guidelines and reports, such as the MIRD Pamphlets, which are technical documents providing detailed methodologies for radiation dosimetry calculations.