Repeated imaging of lung cancer development using PIXSCAN, a low dose microCT scanner based on XPAD hybrid pixel detectors

PIXSCAN is the first micro-CT prototype based on XPAD hybrid pixel detectors whose properties (high signal to noise ratio and detection efficiency) theoretically allow imaging at low irradiation dose. We have tested the impact of repeated imaging sessions with PIXSCAN on living mice. Mice were subjected on average to 10 imaging sessions over two weeks without any detectable sign of X-ray injuries as assessed by spontaneous activity in the cage, examination of hair and skin, or comparison of lung absorbing properties for X-rays. PIXSCAN was therefore used to detect and non-invasively monitor the progression of lung metastasis in a murine model of cancer. Aim was two-fold: i) to provide imaging assistance to decide timing of animal sacrifice for subsequent histological characterization; ii) to optimize imaging protocol to allow direct evaluation of new therapeutic agents to stop cancer progression. Comparing in vivo tomographic reconstruction of freely breathing mice with post mortem examination of their lungs, we have shown that identification and localization of millimetric tumors was compatible with X-ray imaging protocol delivering only 10 mGy per exam.