MIRD pamphlet No. 25: MIRDcell V2.0 software tool for dosimetric analysis of biologic response of multicellular populations

Patients undergoing nuclear medicine procedures for cancer therapy are administered radiopharmaceuticals that emit various types of radiation. Because radiation has differential delivery to and uptake by cells in tissue, radiation exposures are often highly nonuniform. Some cell populations in a tissue may contain widely different amounts of radioactivity, whereas other cell populations in the same tissue may contain no radioactivity, referred to as labeled and unlabeled cells, respectively. Furthermore, the toxicity of the radiations emitted can depend on the location of the radioactive decay within the cell (e.g., nucleus vs. cytoplasm). Therefore, the response of a given cell depends on the absorbed dose received from radiations emitted by decays within the cell (self-dose) and emitted by decays in neighboring cells (cross-dose), among other factors. Taken together, these variables make it difficult to predict the response of cell populations to radiopharmaceuticals. Accordingly, to assist in designing treatment plans for therapeutic radiopharmaceuticals, an applet software application called MIRDcell was developed. This applet models the distribution of radiopharmaceuticals in tissues, calculates the distribution of radiation dose, models responses on a cell-by-cell basis, and predicts the surviving fraction of the labeled and unlabeled cell populations. MIRDcell can be accessed at http://mirdcell.njms.rutgers.edu/.