# Utilization of Lutetium Background Radiation for Quantitative Total-Body PET Imaging

> **NIH NIH R03** · UNIVERSITY OF CALIFORNIA AT DAVIS · 2022 · $79,021

## Abstract

Project Summary/Abstract
Positron emission tomography (PET) is widely used as a clinical and research tool for diagnosis, prognosis, and
treatment planning in oncology, while increasingly being adopted in other fields such as cardiology, neurology,
and inflammatory disorders. The latest generation of PET scanners offer significant enhancements in sensitivity
with an increased axial imaging extent. The sensitivity gain in these scanners directly translates into improved
image quality in standard imaging protocols and enables use of new scan protocols with ultrashort time frames
or ultralow-dose scans. The long axial-field-of-view (AFOV) in these systems offers unique opportunities and
challenges in addressing quantification barriers in PET. Among a wide range of factors affecting the quantitative
accuracy of PET, the effects from attenuation, scatter, and human motion are common and predominant. In this
project, we aim to utilize the lutetium (Lu) background radiation present in these scanners: first, for attenuation
correction (AC) and scatter correction (SC), and second, for motion correction (MC), with particular attention on
ultralow-dose PET scans. AC and SC are usually performed using the attenuation maps (μ-maps) obtained from
a computed tomography (CT) scan performed prior to PET. As ultralow-dose PET scans are now made possible
with long-AFOV PET scanners, it is desirable to further reduce the radiation dose by estimating the μ-maps from
the Lu background radiation, when an additional CT scan can be avoided. We will primarily study our
methodology with the uEXPLORER scanner, which is the world’s first total-body PET scanner that can
simultaneously image the entire body, and will employ the Lu background data together with the PET emission
data in maximum likelihood reconstruction of attenuation and activity (MLAA). We expect to achieve improved
quantitative accuracy compared to prior studies as the high sensitivity and increased flux of background radiation
originating from the large volume of Lu-based detectors in long-AFOV PET scanners, in addition to the ability of
scanning the entire body in a single bed position, enables more efficient utilization of the Lu background. Finally,
as human motion causes quantification bias by introducing image blurring and attenuation-emission mismatches,
we will use a data-driven total-body MC framework to correct both the Lu-background-based μ-maps and the
PET images. We will study the effects of different types of motion on PET quantification in two cases: first, when
PET emission data is used for motion-estimation and second, feasibility of utilizing the Lu background data in
motion-estimation, particularly in ultralow-dose scans or body regions with low radiotracer uptake, in which
standard emission-based data-driven motion estimation methods are prone to error. This is especially important
in total-body PET, as motion in one region of body could affect the AC and SC in other regions. We believe thi...

## Key facts

- **NIH application ID:** 10352106
- **Project number:** 1R03EB032457-01
- **Recipient organization:** UNIVERSITY OF CALIFORNIA AT DAVIS
- **Principal Investigator:** Negar Omidvari
- **Activity code:** R03 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $79,021
- **Award type:** 1
- **Project period:** 2021-12-01 → 2023-11-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10352106

## Citation

> US National Institutes of Health, RePORTER application 10352106, Utilization of Lutetium Background Radiation for Quantitative Total-Body PET Imaging (1R03EB032457-01). Retrieved via AI Analytics 2026-05-26 from https://api.ai-analytics.org/grant/nih/10352106. Licensed CC0.

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