Как выбрать гостиницу для кошек
14 декабря, 2021
In a PET camera, there are rings of detectors around the patient. The two photons resulting from annihilation fly in opposite directions and will be detected by two detectors at almost the same time. The line of event can be determined by connecting the two detectors (Figure 12.12). So, in contrast to gamma cameras, we do not need a collimator for PET imaging, and consequently both the sensitivity and spatial resolution of PET are better than those of a regular gamma camera for human imaging. Moreover, since the pairs of photons hitting a particular pair of detectors always travel the same path length inside the patient’s body (independent of the position where the annihilation occurred along the line), the correction for attenuation is more straightforward.
The rings can simultaneously detect radiation emitted in all directions, so PET is capable of acquiring dynamic tomographic studies as well. Utilizing this, in the beginning, PET was mostly used for research purposes, primarily for pharmaco — and receptor kinetic brain studies. Today, most of the PET studies are clinical: they are used to search for tumors and metastases.