The performance of a novel designed x-ray CT scanning geometry is investigated. Composed of a specially designed tungsten collimation mask and a high resolution flat panel detector, this scanning geometry provides high efficient data acquisition allowing dose reduction potentially up to 50%. In recent years a special type of scanning geometry has been proposed. A first prototype of this geometry called CTDOR( CT with Dual Optimal Reading) has already been built. Despite many drawbacks, resulting images have shown promising potential of dual reading. The approach of gaining two subsets of data has anew been picked up and come to terms with a novel designed CT scanner for breast imaging. The main idea consists of collimating the X-ray beam through a specially designed shielding mask thereby reducing radiation dose without compromising image quality. This is achieved by hexagonally sampled Radon transform and image reconstruction with the especially suitable OPED (orthogonal polynomial expansion on disk) algorithm. This work now presents the development and evaluation of the novel designed breast CT system. Therefore simulated phantom data were obtained to test the performance of the scanning device and compared to a standard 3rd generation scanner. Retaining advantages such as scatter-correction potential and 3D-capability, the proposed CT system yields high resolution images for breast diagnostics in low energy ranges. Assuming similar sample size, it is expected that the novel designed breast CT system in conjunction with OPED outperforms the standard 3rd generation CT system combined with FBP (filtered back projection).
A novel designed x-ray CT scanning geometry is proposed. Composed of a specially designed tungsten collimation mask
and a flat panel detector, which is placed inside the mask, this scanning geometry provides high efficient data acquisition
allowing dose reduction potential by a factor of two.
In recent years a first prototype of the CTDOR geometry (CT with Dual Optimal Reading) has been evaluated. It
consisted of a discontinuous ring of detectors fixated on X-Ray absorbing material. The source and an outer detector
were mounted on a gantry rotating around the inner static detector and the patient. Despite many drawbacks, resulting
images have shown promising potential of dual reading. Based on those results, the present work presents further
development and improvement of the recommended scanner geometry. The main idea consists of collimating the X-ray
beam through a specially designed shielding mask thereby reducing radiation dose and structuring data without
compromising image quality. An especially developed high precision laser-beam cutting process assures an accurate
mask crafting with tungsten shielding and window sizes of 300μm.
Additionally, simulation data were obtained with Monte Carlo calculations to test the dose reduction potential of the
scanning device. Retaining advantages of the CTDOR geometry such as 3D-capability, built-in capacity of scatter
correction and radiation structuring, a high-precision manufactured collimation mask of novel designed CT-scanner
enables high resolution images for breast-imaging in low energy ranges.