# EARL compliance on the Biograph Vision Quadra PET-CT: phantom study for static and continuous bed motion acquisitions

## TL;DR

This study evaluates how to meet EARL standards on a new PET-CT system while maintaining image quality.

## Contribution

Identifies reconstruction parameters for EARL compliance in static and continuous bed motion PET acquisitions.

## Key findings

- EARL compliance can be achieved with specific reconstruction parameters across all acquisition modes.
- Compliance significantly reduces image quality, particularly in Ultra-High Sensitivity mode.
- Patient images with EARL-compliant parameters appear smoother but with reduced contrast.

## Abstract

Long axial field-of-view (LAFOV) PET systems like the Siemens Biograph Vision Quadra offer unprecedented sensitivity and imaging capabilities, but compliance with EARL standards across all acquisition modes remains unexplored. This study aimed to identify reconstruction parameters meeting EARL 1 and 2 compliance for static and continuous bed motion (CBM) acquisitions in High Sensitivity (HS) and Ultra-High Sensitivity (UHS) modes on the Quadra. The research focused on optimising image quality while maintaining compliance with quantitative standards.

The International Electrotechnical Commission (IEC) body phantom was filled with 18F-FDG in a 10:1 sphere-to-background activity ratio and scanned at five positions across the field of view (FOV) using static and CBM acquisitions in HS and UHS modes. Reconstructions used standard clinical parameters, varied with Gaussian filters (1–7 mm) and matrix sizes (440, 220, 128). EARL compliance was assessed with the EARL tool to evaluate SUV recovery coefficients (RCSUVmean, RCSUVmax, RCSUVpeak). Patient images were reconstructed using standard and EARL-compliant parameters for comparison.

Reconstruction parameters achieving EARL compliance were identified for all acquisition modes, with no differences between static and CBM reconstructions. Achieving EARL compliance required significant image quality reductions, especially for EARL 1, with greater degradation in UHS mode. Patient images reconstructed with EARL-compliant parameters appeared smoother and had reduced contrast compared to clinical reconstructions.

While EARL compliance ensures quantitative standardisation, it significantly reduces image quality, especially on advanced LAFOV PET systems. An updated “EARL 3” standard is needed to reflect the capabilities of modern systems.