NEW APPROACH TO DETECT CARDIAC-PULMONARY MOTION FOR MICRO-CT SYSTEM

Non-invasive cardiac-pulmonary gating is proposed to improve the imaging resolution. It produces signals based on the cardiac-pulmonary motion of an animal in real-time. The system with the non-invasive gating consists of a digital signal processor （DSP）, an electrocardiography （ECG） detection circuit and a thermoeouple circuit. An enhanced R wave detection algorithm based on zero crossing counts is used to adjust the low sample frequency associated with the respiratory rate of an animal. The thermocouple recognizes the respiration phase by sensing the temperature changes of the nasal airflow of an animal. The proposed gating can accurately generate the gating signal for freely breathing mice （weight of around 0.03 kg）, and its respiratory signal is too weak to be detected. Apart from non-invasiveness, compared with other existing gating techniques, it occupies minimal space at lower cost. Actually, it can be used in micro-computed tomography （CT） and other systems needed to detect the cardiac-pulmonary motion. Several tests validate that the proposed cardiac-pulmonary gating can generate the gating signal as required. By using the gating technique, the image resolution is improved.

Fast fluorescence lifetime imaging techniques:A review on challenge and development

Fluorescence lifetime imaging microscopy(FLIM)is increasingly used in biomedicine,material science,chemistry,and other related research fields,because of its advantages of high specificity and sensitivity in monitoring cellular microenvironments,studying interaction between proteins,metabolic state,screening drugs and analyzing their efficacy,characterizing novel materials,and diagnosing early cancers.Understandably,there is a large interest in obtaining FLIM data within an acquisition time as short as possible.Consequently,there is currently a technology that advances towards faster and faster FLIM recording.However,the maximum speed of a recording technique is only part of the problerm.The acquisition time of a FLIM image is a complex function of many factors.These include the photon rate that can be obtained from the sample,the amount of information a technique extracts from the decay functions,the fficiency at which it determines fluorescence decay parameters from the recorded photons,the demands for the accuracy of these parameters,the number of pixels,and the lateral and axial resolutions that are obtained in biological materials.Starting from a discussion of the parameters which determine the acquisition time,this review will describe existing and emerging FLIM techniques and data analysis algo-rithms,and analyze their performance and recording speed in biological and biomedical applications.