Another angle: 237 is also the atomic number of a nuclide, but that's probably unrelated. Alternatively, it might be part of a document name like "MIRD-237" but I'm not sure. If the user is referring to a document from 2021 related to MIRD, perhaps they mean MIRD Pamphlet 24, but the number 237 is confusing.
In 2021, there was the publication of MIRD Working Group 9's document on the standardization of dosimetry calculations. But that's not 237. Another thought: sometimes conference proceedings include numbers, like the 2021 SNMMI Annual Meeting, which might have a specific presentation number (e.g., presentation 237). If the user is referring to a presentation or paper from that conference, that could be the context.
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.
Alternatively, "MIRD237" could be a specific study, project, or even a code name for an internal project. If it's a typo, maybe it's "MIRD 23-7" or another combination. Let me think if there are any recent guidelines from 2021.