One limitation in our research was the study sample. Live animals were not imaged. Despite the advances in spatial resolution and contrast of phase contrast imaging, real-time Xray phase tomography of the live animals has remained difficult. Live animals can only be imaged in two dimensions. The major obstacle in realizing this is the motion artifacts caused by breathing and cardiac motion of the animals, which will lead to serious blur in the reconstructed CT images. It is well known that the alveoli in lung are very small; any noise can influence the accuracy of the imaging result. Some attempts have been made to live animals imaging by taking the projection images at a specific breathing phase in synchrony with ECG signals [26] . But the animals have to be anaesthetized and with their breathing controlled by a ventilator. High-speed X-ray phase tomography may be another possible solution to live animal imaging by substantially reducing the imaging time. In fact, finishing a CT in one respiration phase is possible but the rotation speed of the sample stage and the time resolution of the detector need to be improved [27] . Another limitation was the lack of pathological samples. In this study, a normal 1-day-old mouse was used. The results proved that IL-XPCI is possible for lung micro-structures observation. Lung disorder models were missing, such as asthma, emphysema and lung cancer. We plan to evaluate these disorder models in our IL-XPCI imaging experiment as next steps, which are in progress now.