High Resolution Inspection for Dental Imaging System
Generating digital X-ray images
Applied Scintillation Technologies (AST) is a UK based manufacturing company that specializes in developing advanced imaging and detection systems in the dental, security, medical and health physics fields. AST has extensive experience in developing custom phosphors and scintillants, which, coupled with a CCD or CMOS camera, are used in intra-oral and panoramic dental systems.
Digital imaging in dental surgeries is rapidly gaining ground due to its many health and practical benefits for both staff and patients. Using CCD or CMOS digital cameras instead of film requires a much lower X-ray dose allowing instant images to be displayed, and eliminates the need for film processing that uses potentially toxic chemicals. In addition, the ability to store digital images on computers facilitates patient record management, long term care and treatment plans.
High-Precision Inspection for High-Precision Diagnostics
AST develops and manufactures imaging devices used in dental X-ray diagnostic systems. Their intra-oral device combines a CCD sensor chip with a fast response X-ray scintillator CsI coating optimized to eliminate potential image blur caused by patient movement during imaging.
The surface quality of the 1.25”x1” CsI coated device requires high-precision measurement to ensure optimum accuracy during the diagnostic stage. Because of the improvements in the structure of the deposited CsI, imperfections are getting smaller and smaller, making them difficult to detect.
AST has developed a high quality proofing system based on an optical inspection microscope and a camera system for X-ray inspection that is used to detect small marks and imperfections in the coating structure, or any other process which may have occurred during the manufacturing stage. An improved camera system equals improved quality control of AST’s products, the majority of which are tested by X-ray.
The system uses a 16 Megapixel Prosilica GE4900 CCD camera by Allied Vision Technologies. The GE4900 features the high quality 35mm format Kodak KAI-16000 CCD image sensor that provides very high resolution as well as low noise and excellent sensitivity for applications such as X-ray imaging.
The GE4900 camera is mounted on a gantry above an X-Y table that has a movement range of 12x12". The height of the camera can be adjusted thanks to a motorized lead screw while lens focus is remotely controlled and adjusted thanks to the use of an EF-mount adaptor. The adaptor supports a wide range of off-the-shelf Canon and Tamron lenses and brings the added benefit of motorized lens control for functions such as iris and focus control to industrial cameras.
The 100mm Canon macro lens is protected from the X-rays by lead glass. The body of the camera has a lead jacket for extra protection. Focus and aperture control are programmatically controlled via the RS-232 peripheral port of the Prosilica GE4900 camera.
The operating software used to analyze results was developed in-house by AST using the AVT/Prosilica SDK. It controls all functions including triggering, gain settings and image processing.
Ensuring High Standards
The best way to detect flaws on the X-ray-sensitive coating is to X-ray them. Firstly, the devices are cleaned and visually inspected to ensure that all process contaminants have been removed. They are then arranged in a grid on a tray and set-up on the X-Y stage. The operating software is used to select which products are tested. The program sets up the stage, camera height, exposure time, lens aperture and focus. Pressing the scan button starts the X-ray and images for each device are taken and stored.
At 10 microns per pixel resolution, the new AST quality proofing system ensures high standards, and quality for their intra-oral X-ray devices for fast and accurate dental diagnostics.