An essential feature of SPECT imaging is collimation of gamma photons, allowing detection of only those photons propagating in the appropriate direction. Parallel beam collimators are widely used in different applications, because reconstruction is straightforward. Fan-beam collimators focus on a focal line parallel to the axis of rotation. For organs centered within the field of view this enha...

The authors present a new method to compensate for the spatially variant detector response in single photon emission computed tomography (SPECT) with varying focal-length fan-beam (VFF) geometry. In this method, the deblurred projection is explicitly expressed as an integral of the collimator blurred data and the fully calibrated system kernel matrix with certain transforms. It needs a little m...

Single photon emission computed tomography (SPECT) is based on the measurement of radiation emitted by a radiotracer injected into the patient. Because of photoelectric absorption and Compton scatter, the gamma photons are attenuated inside the body before arriving at the detector. A quantitative reconstruction must consider the attenuation, which is usually nonuniform. Novikov has derived an e...

The pinhole collimator is currently the collimator of choice in small animal single photon emission computed tomography (SPECT) imaging because it can provide high spatial resolution and reasonable sensitivity when the animal is placed very close to the pinhole. It is well known that if the collimator rotates around the object (e.g., a small animal) in a circular orbit to form a cone-beam imagi...

Images generated with helical scanning are degraded by partial volume artifacts caused by an increased slice thickness when compared to conventional computed tomography (CT) scanning. The slice thickness for a helical scan is proportional to the sum of the thickness of the fan of radiation and the distance the patient moves during data acquisition. We present a method called moving beam helical...

X-ray fluorescence computed tomography (XFCT) was performed on a high-intensity synchrotron radiation source or a pencil beam with a long exposure time due to the low emission and detection efficiency of x-ray fluorescence photons. For the first time, the feasibility and experimental results of a full-field fan-beam XFCT with a photon-counting detector array are presented. This full-field fan-b...

Objective(s): The purpose of this study was to examine the optimal reconstruction parameters for brain dopamine transporter SPECT images obtained with a fan beam collimator and compare the results with those obtained by using parallel-hole collimators.Methods: Data acquisition was performed using two SPECT/CT devices, namely a Symbia T6 and an Infinia Hawkeye 4 (device A and B) equipped with fa...