Despite recent advances in dental radiography, the diagnostic accuracies for some of the most common dental diseases have not improved significantly, and in some cases remain low. Intraoral x-ray is the most commonly used x-ray diagnostic tool in dental clinics. It however suffers from the typical limitations of a 2D imaging modality including structure overlap. Cone-beam computed tomography (CBCT) uses high radiation dose and suffers from image artifacts and relatively low resolution. The purpose of this study is to investigate the feasibility of developing a stationary intraoral tomosynthesis (s-IOT) using spatially distributed carbon nanotube (CNT) x-ray array technology, and to evaluate its diagnostic accuracy compared to conventional 2D intraoral x-ray. A bench-top s-IOT device was constructed using a linear CNT based X-ray source array and a digital intraoral detector. Image reconstruction was performed using an iterative reconstruction algorithm. Studies were performed to optimize the imaging configuration. For evaluation of s-IOT’s diagnostic accuracy, images of a dental quality assurance phantom, and extracted human tooth specimens were acquired. Results show s-IOT increases the diagnostic sensitivity for caries compared to intraoral x-ray at a comparable dose level.
XinRay Systems Inc has a rectangular x-ray computed tomography (CT) imaging setup using multibeam x-ray tubes.
These multibeam x-ray tubes are based on cold cathodes using carbon nanotube (CNT) field emitters. Due to their
unique design, a CNT x-ray tube can contain a dense array of independently controlled electron emitters which generate a linear array of x-ray focal spots. XinRay uses a set of linear CNT x-ray tubes to design and construct a stationary CT setup which achieves sufficient CT coverage from a fixed set of views. The CT system has no moving gantry, enabling it to be enclosed in a compact rectangular tunnel. The fixed locations of the x-ray focal spots were optimized through simulations. The rectangular shape creates significant variation in path length from the focal spots to the detector for different x-ray views. The shape also results in unequal x-ray coverage in the imaged space. We discuss the impact of this variation on the reconstruction. XinRay uses an iterative reconstruction algorithm to account for this unique geometry, which is implemented on a graphics processing unit (GPU). The fixed focal spots prohibit the use of an antiscatter grid. Quantitative measure of the scatter and its impact on the reconstruction will be discussed. These results represent the first known implementation of a completely stationary CT setup using CNT x-ray emitter arrays.