# Cloud/Subscription based, Customer-Responsive Dosimetry Tool for alpha-Particle Emitters

> **NIH NIH R44** · RADIOPHARMACEUTICAL IMAGING AND DOSIMETRY, LLC · 2024 · $898,497

## Abstract

Direct to Phase 2 SBIR
Cloud/Subscription based, Customer-Responsive Dosimetry Tool for α-Particle Emitters
PROJECT SUMMARY
Radiopharmaceutical therapy (RPT) – defined as a form of cancer therapy that uses targeted radionuclides to
deliver radiation to cancer cells and their microenvironment – is a growing area with many pharmaceutical
companies developing products in this area. The dosimetric evaluation of therapeutic radiopharmaceuticals is a
key requirement for regulatory approval and treatment planning. Currently available dosimetry software
packages were developed for diagnostic imaging or therapies involving beta emitters applications. These do not
include features essential for α-emitter radiopharmaceutical therapy (αRPT). In this Phase II application, we will
build upon our previous work to transition from a radiological protection-based dosimetry paradigm, where the
biologic endpoint is long-term stochastic effects, to one whose endpoint is normal tissue toxicity and therapeutic
efficacy. We will implement a methodology that uses macroscopic activity measurements to derive activity
distributions at the microscopic level (we call it macro-to-micro or M2µ). Because of the short range and high
potency of α-particles, and the inability to assess microscale activity distributions directly in human patients with
current imaging technology, the M2µ formalism is essential to assessing normal organ toxicity for αRPT. The
M2µ methodology was developed at Johns Hopkins and licensed to Rapid®, LLC. No other dosimetry product
has implemented the M2µ technology. The work proposed in this Phase II application will be incorporated into
3D-RD-S, our cloud-based Medical Internal Radiation Dose (MIRD) Committee S-value-compatible dose
calculation tool. Based on clients’ requests, this area has been identified as the area of greatest need. The
specific aims for this application are: 1. Establish a library of microscale S-values for three dose-limiting tissues
relevant to αRPT (kidneys, bone marrow, salivary glands). 2. Establish corresponding apportionment factors that
map whole-organ activity concentration to sub-structure activity concentrations 3. Implement customizable M2µ
dosimetry by allowing user uploads of a microscale geometry for a given macroscopically defined tissue. 4.
Integrate, and computationally test, the M2µ functionality within the 3D-RD-S platform; using the already built-in
uncertainty calculation platform, calculate the uncertainty associated with microscale absorbed doses. 5. Since
α-emitter dosimetry and the M2µ method are likely to be unfamiliar to users that are new to αRPT, we will develop
on-line educational materials accessible within the 3D-RD-S platform. Aim 5 reflects the importance of educating
both αRPT practitioners and the regulatory authorities regarding the special considerations related to α-emitter
dosimetry. The on-line material builds on the 3D-RD-S cloud-based platform. Support for this grant will complete
a compon...

## Key facts

- **NIH application ID:** 10921546
- **Project number:** 1R44CA291420-01
- **Recipient organization:** RADIOPHARMACEUTICAL IMAGING AND DOSIMETRY, LLC
- **Principal Investigator:** ERIC C. FREY
- **Activity code:** R44 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $898,497
- **Award type:** 1
- **Project period:** 2024-08-05 → 2026-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10921546

## Citation

> US National Institutes of Health, RePORTER application 10921546, Cloud/Subscription based, Customer-Responsive Dosimetry Tool for alpha-Particle Emitters (1R44CA291420-01). Retrieved via AI Analytics 2026-06-12 from https://api.ai-analytics.org/grant/nih/10921546. Licensed CC0.

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