Study on the Correction Method of Radiation Damage of X-ray Conversion Screen

Background  High-resolution X-ray photography utilizes the strong penetration capability of MeV-level X-rays and the high-resolution capacity of microfocus X-ray machines to conduct high-resolution transmission photography and image analysis on devices, thereby obtaining precise profile parameters of the device under inspection. During the process of high-resolution X-ray imaging of the device, long timed exposure and high doses of radiation can damage the X-ray conversion screen, leading to a continuous decrease in its conversion efficiency.

Purpose This study focuses on the radiation damage issue of the X-ray conversion screen in high-resolution X-ray photography. The goal is to establish a correction method for irradiation damage image.

Methods Starting with the grayscale data from areas within a certain workpiece’s DR (Digital Radiography) image set that do not contain the device, the research analyzes the changes in image grayscale as a function of radiation dose and exposure time, establishing a model for the change pattern of DR image grayscale. The change in image grayscale due to radiation dose is decomposed into two components: a linear decline caused by damage to the conversion screen and random fluctuations caused by variations in the X-ray source dose rate. By fitting a linear curve to the distribution pattern curve, these two components are separated, where the slope of the linear component represents the radiation damage coefficient of the conversion screen. Research has also been conducted on methods to correct for radiation damage to the conversion screen.

Results After correction, the average relative error between the grayscale of the corrected DR images and the true value images is less than 0.6%, which is nearly an order of magnitude smaller than before correction.

Conclusions The established method for correcting radiation damage to the conversion screen effectively corrects for unexpected changes in DR image grayscale due to damage to the conversion screen and fluctuations in the light source dose, laying the foundation for more precise and automated quantitative image analysis in subsequent steps.