A robust approach for gantry tilt calculation and correction of zoom-in PET system by using PET image sinograms

Positron Emission Tomography (PET) scans are non-invasive three dimensional imaging technique that provide a 3D image of functional processes of cells in the body. Positron Emission Tomography techniques are mainly used in oncology (study of cancer) in order to detect the presence of cancerous cells. The patient is injected with a solution of tracer that is a radionucleotide that decays emitting positrons. Gamma rays are generated by the collisions of the positrons and electrons by a process called annihilation. Annihilation creates two gamma photons that move exactly in opposite directions i.e,180 degree to each other. The scanner comprising of array of detectors detect the emitted gamma rays in the form of scintillations. The scintillations on the detector generate an image of the internal organs of the patient. Since malfunctioning cells consume more amount of glucose in the tracer, the gamma rays in that area can be differentiated. If the emitted gamma ray is incident exactly at a gantry angle zero, then scan image is perfectly acquired. The incidence of gamma rays at a gantry angle with an offset away zero results in a image with gantry tilt. A robust novel system is needed to correct the gantry tilted image in a PET imaging system. A tilt corrected image is mandatory for clinical analysis of severity of disease and study. This paper proposes a robust approach to correct a PET scan image with gantry tilt.