The visualisation of two-dimensional dose distribution on X-ray CT using radiochromic film

TL;DR

This study visualized two-dimensional dose distributions in X-ray CT using radiochromic film, highlighting the effects of phantom size and exposure parameters, and emphasizing the need for improved calibration for clinical accuracy.

Contribution

It demonstrates the use of radiochromic film and visualization techniques to analyze 2D dose distributions in X-ray CT, addressing limitations of traditional ionization chamber measurements.

Findings

Dose distribution varies with phantom presence and parameters.

3D surface plots and subtraction images effectively visualize dose differences.

No significant change in dose distribution with phantom length variations.

Abstract

X-ray CT dose measurement has mainly been performed using an ionization chamber dosimeter. Therefore, the dose distribution has not been sufficiently studied. We investigated the importance of evaluating the two or three-dimensional dose distributions for X-ray computed tomography (CT). To confirm this purpose, we investigated the effects of phantom size and exposure parameters on the phantom diameter. We performed 12 scans using XR-QA2 film and cylindrical acrylic phantoms of two lengths. The tube current and slice thicknesses were varied as exposure parameters. The dose distribution of the primary and scattered radiation was visu-alised using ImageJ. The results were evaluated using the profile curves, three-dimensional surface plots, and subtrac-tion dose images. We observed changes in the dose distributions for scans with and without phantoms. However, no significant differ-ence in the dose distribution was observed with changes in the lengths of the phantom. To visualise the dose distribution, three-dimensional surface plots and subtraction images were found helpful. We must confirm that the dose distribution does not change for phantoms with multiple diameters in future studies. For using a clinical application, accurate quantitative assessment of dose distribution requires improved accuracy of the calibration curve.