# A Multimodal Imaging Approach Towards the Reduction of Proton Beam Range Uncertainties

> **NIH NIH R21** · BRIGHAM AND WOMEN'S HOSPITAL · 2020 · $193,500

## Abstract

Cancer is a significant health problem with an estimated 1,699,780 new cases of cancer and 600,920 deaths in
the US during 2017. Approximately 50% of cancer patients will have radiation therapy as part of their course of
treatment. Standard x-ray radiation therapy treatment beams suffer from high entrance doses. The physics of
x-ray radiation therapy fundamentally limits the amount of radiation that can be delivered to a target while
sparing the surrounding normal tissues. Proton therapy is a rapidly growing radiation therapy modality with
significant clinical potential to overcome these limitations. The reduction of doses to normal tissue may be
significant in pediatric patients where studies have shown that proton therapy can significantly lower rates of
secondary malignancies. Greater doses to targets, such as those achievable by proton therapy, can improve
local control and greater overall survival. Proton therapy has the potential to significantly reduce radiation
doses to normal tissue while increasing the dose to targets however its clinical benefit has been
limited by delivery accuracy. Proton therapy has the distinct advantage of being able to deliver a high dose
at deep depths while potentially sparing healthy tissue proximal and distal to the target position. This
advantage is physically manifested by the Bragg peak in which the proton deposits a significant portion of its
dose immediately before reaching the end of its range. The position of the Bragg peak in tissue is determined
using the stopping power ratio (SPR) relative to water. Errors in the determined SPR translate to positional
inaccuracies of the Bragg peak within the patient relative to the planned dose delivery position. Proton range
uncertainty has been cited as the main factor limiting the ability for proton therapy to spare normal
tissues to their full potential. Recently, we developed a novel method to determine mean ionization potential,
Im, (and SPR) using MRI which will allow for more highly tailored conformal proton therapy treatments. This
methodology has distinct advantages over current methods due to our method’s tissue sensitivity and stability
to noise. To our knowledge, no equally effective method is currently being employed by any other teams
anywhere in the world. The goal of this project is to improve the accuracy of proton therapy treatments
using a novel multi-modal imaging technique with the potential for practical application in most clinics.
To achieve this goal, we must further develop this method to create accurate SPR maps in phantoms (Aim 1),
validate these SPR maps in ex vivo animal tissues and determine uncertainties (Aim 2), and conduct a
prospective virtual clinical trial to test the hypothesis that reduced SPR uncertainties lead to improvements on
dosimetry and outcomes (Aim 3). The work proposed builds on our initial theory and supporting data that show
the potential for high accuracy in SPR determination. The innovation of this project is i...

## Key facts

- **NIH application ID:** 10113210
- **Project number:** 7R21EB026086-03
- **Recipient organization:** BRIGHAM AND WOMEN'S HOSPITAL
- **Principal Investigator:** Atchar Sudhyadhom
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $193,500
- **Award type:** 7
- **Project period:** 2018-04-01 → 2023-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10113210

## Citation

> US National Institutes of Health, RePORTER application 10113210, A Multimodal Imaging Approach Towards the Reduction of Proton Beam Range Uncertainties (7R21EB026086-03). Retrieved via AI Analytics 2026-05-26 from https://api.ai-analytics.org/grant/nih/10113210. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*