Correlation between X-ray tube current exposure time and X-ray photon number in GATE

TL;DR

This study establishes a linear relationship between X-ray tube current exposure time and photon number in GATE simulations, aiding dose estimation and image quality optimization in X-ray imaging modalities.

Contribution

It introduces a method to accurately set the photon number in GATE simulations based on tube current exposure time, improving simulation accuracy for X-ray imaging.

Findings

Linear regression model between photon number and exposure time

Enhanced accuracy in dose estimation for X-ray imaging

Facilitates better simulation setup in GATE platform

Abstract

The image quality of X-ray imaging relies heavily on the X-ray output number which is dependent on the X-ray tube current and the exposure time. Hybrid X-ray imaging modalities like X-ray luminescence CT (XLCT) and X-ray fluorescence CT (XFCT) rely on the intensity of the X-ray tube to provide an accurate image reconstruction of the nanoprobe distribution in the imaging sample. A limiting factor of good image quality is the radiation dose that will be delivered to the imaging object. To accurately estimate the absorbed dose in an imaging protocol, it is better to simulate the X-ray imaging with a Monte Carlo platform such as GATE (Geant4 Application for Tomographic Emission). However, the input of GATE is a photon number of the simulated X-ray tube. So far, there is no good way to setup the photon number for a desired X-ray tube current. In this work, the accumulated radiation dose of a micro-CT X-ray tube at different current exposure times was recorded with a general-purpose ion chamber. GATE was used to model the total absorbed dose (cGy) in the sensitive volume of the ion chamber with different X-ray output numbers. A linear regression model was generated between the X-ray photon number in the GATE simulations and the tube current exposure time (mAs). The findings of this work provide an approach to correlate the X-ray tube current exposure time (mAs) to the X-ray photon number in GATE simulation of the X-ray tube.