# Accurate 4D Liver Tumor Localization for Radiotherapy using Contrast-Agent-Free X-ray Imaging and Liver Biomechanical Modeling

> **NIH NIH R01** · UT SOUTHWESTERN MEDICAL CENTER · 2020 · $373,721

## Abstract

ABSTRACT
Radiotherapy has become an increasingly effective technique to treat patients affected by primary and metastatic
liver cancers, especially after the advent of stereotactic body radiotherapy (SBRT). SBRT delivers a large and
focused radiation dose to liver tumors and achieves superior local control and survival. However, for current liver
SBRT, a volume usually much larger than the actual tumor (with treatment margins up to 15 mm beyond the
tumor boundary) is treated, to account for tumor localization uncertainties under the cone-beam computed
tomography (CBCT) image guidance. Such a large treatment volume incurs more radiation to normal liver tissues
and organs-at-risks and raises the concern of normal tissue toxicity, especially for patients with liver cirrhosis
and a limited healthy liver tissue reserve. It also prevents further dose escalation to maximize the effectiveness
of SBRT. Currently, there lacks a reliable technique to accurately localize liver tumors by CBCT, mostly due to
the respiration-induced liver motion and the low contrast of liver tumors against the normal liver tissues. In
response to PAR-19-158, we propose to develop a biomechanical modeling-guided 4DCBCT technique (Bio-
4DCBCT), which generates 4DCBCT images to capture the liver tumor motion for accurate 4D localization. The
Bio-4DCBCT incorporates liver biomechanical modeling into the 4DCBCT generation process, which can
substantially improve the localization accuracy of CBCT at low-contrast regions. The goal of this study is to
develop, optimize and validate the Bio-4DCBCT technique to achieve ~ 2 mm tumor localization accuracy. In
this study we will pursue three specific aims: SA1. Optimize Bio-4DCBCT through a retrospective patient study.
SA2. Evaluate Bio-4DCBCT by developing a motion-enabled, deformable, physical liver phantom. SA3. Evaluate
Bio-4DCBCT through a prospective clinical study by comparing Bio-4DCBCT with the current clinically-applied
techniques. The innovation of the project is the Bio-4DCBCT technique and its application for accurate 4D liver
tumor localization, which leads to substantial treatment volume/margin reduction to achieve safer, more viable
and more effective liver SBRT. The Bio-4DCBCT technique is developed on the conventional CBCT system
under standard image acquisition protocols, which will be readily applicable in radiotherapy clinics worldwide
without hardware upgrade or image acquisition protocol change. The successful clinical translation of this
technology is expected to create a favorable shift in current tumor localization paradigms, not only for liver but
also for other tumor sites where low tissue contrast adversely affects the radiotherapy treatment accuracy.

## Key facts

- **NIH application ID:** 9972485
- **Project number:** 1R01CA240808-01A1
- **Recipient organization:** UT SOUTHWESTERN MEDICAL CENTER
- **Principal Investigator:** You Zhang
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $373,721
- **Award type:** 1
- **Project period:** 2020-06-01 → 2024-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9972485

## Citation

> US National Institutes of Health, RePORTER application 9972485, Accurate 4D Liver Tumor Localization for Radiotherapy using Contrast-Agent-Free X-ray Imaging and Liver Biomechanical Modeling (1R01CA240808-01A1). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9972485. Licensed CC0.

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