A new component approach efficiency normalization for 3D PET

Efficiency normalization is to correct the non-uniform response of the 3D PET detector due to the scanner´s geometry, crystal non-uniformity, and gain variation in the photo-multiply-tubes. In the literature, most of the component approach detector efficiency normalization is applied to block-design ring scanner. In this paper, we propose a new component normalization method for Philips´ non-block design ring scanner, where the normalization is mainly consists of two components, the crystal efficiency and the detector geometry. The derivation is based on the measured data´s physics model, along with an assumption, so that the crystal efficiency can be separated from the model and both terms can be estimated independently. The crystal efficiency is calibrated using a uniform cylinder phantom. A minimum-least-square estimation method is used to smooth the noisy crystal efficiency. The detector geometry is calibrated using a stationary uniform plane phantom since it is independent of the projection ray´s azimuthal angle. The result is then applied with a radial solid angle correction to compensate for the plane source´s unusual geometry. This technique is finally validated with a uniform cylinder phantom reconstruction along with scatter and attenuation correction