# A Proton Tomography System for Optimization of Proton Therapy

> **NIH NIH R44** · PROTONVDA LLC · 2021 · $912,963

## Abstract

Abstract
Proton therapy is rapidly expanding in the United States. Currently, the calculation of proton range in proton
therapy patients is based on a conversion of CT Hounsfield Units of patient tissues to proton relative stopping
power. Uncertainties in this conversion necessitate larger proximal and distal planned target volume margins.
These larger margins increase the dose to nearby healthy tissues, causing unwanted and avoidable toxicities.
Proton computed tomography (pCT) avoids these uncertainties by directly measuring proton stopping power,
and this can drastically reduce the planned target volume, thus directly reducing toxicity. Proton radiography
(pRad) has the capability to accurately align the patient to the proton beam and quantify anatomical
consistency and proton range in the treatment position just prior to treatment, which will lead to more
consistent target coverage, yielding improved patient outcomes. Clinical proton imaging systems must provide
pCT as well as pRad capability. This project aims to achieve the advances that will ensure the full functionality
of proton imaging in a clinical environment and demonstrate a proton imaging system with a path to FDA
clearance. These key improvements in proton therapy are an essential requirement as the field of radiation
oncology moves toward hypofractionation (higher dose treatments given in fewer fractions).
ProtonVDA (https://www.protonvda.com/), with a recent Phase II SBIR grant, has demonstrated the first fully
functional prototype of a system able to take and promptly display accurate pRad images with clinical proton
pencil beam scanning systems using very low intensity to analyze individual protons. While a fully functional
pCT system does not yet exist, this project will involve co-investigators from Loma Linda University with
extensive experience with a preclinical pCT system. ProtonVDA’s technology will be used to develop a fully
functional pCT prototype. Whereas pRad uses a single beam direction, pCT requires a complete set of angles
spanning at least 180 degrees in the object reference frame. This can be achieved either with a fixed pCT
system and proton beam while rotating the object or with a fixed object while rotating the pCT system along
with the proton beam. In both cases, precise information on any mechanical movements within the beam
delivery, imaging, and object reference frames is essential, because effects from axis misalignment or
mechanical sagging can significantly degrade image quality. Therefore, the prototype will incorporate an optical
tracking system to measure and correct for these movements. Project collaborators from Provision
(https://provisionhealthcare.com/) have previously demonstrated the use of optical tracking for patient
positioning. After development of the pCT system, tests using pCT-planned proton beams applied to phantoms
containing dosimetric films will verify the clinically relevant accuracy of pCT.

## Key facts

- **NIH application ID:** 10120657
- **Project number:** 5R44CA243939-02
- **Recipient organization:** PROTONVDA LLC
- **Principal Investigator:** Don F DeJongh
- **Activity code:** R44 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $912,963
- **Award type:** 5
- **Project period:** 2020-04-01 → 2023-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10120657

## Citation

> US National Institutes of Health, RePORTER application 10120657, A Proton Tomography System for Optimization of Proton Therapy (5R44CA243939-02). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10120657. Licensed CC0.

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