Radon transform is an interesting mathematical topic in its own right as well as widely applicable to Computerized Tomography(CT). In this talk, I introduce the basic properties of Radon transform and the important issues in CT. One of Radon-type transforms is the spherical Radon transform which assigns to a given function its integrals over a set of spheres. There are many types of spherical Radon transforms depending on the choice of variables. Some transforms are related to Photoacoustic tomography, which is new biomedical imaging modality. I mainly introduce these spherical Radon transforms.