Medical X-Ray Tube Spectra for Mammography and Radiology

Features

• Direct Measurement Spectra
• End Point Energy (kVp)
• See what the patient gets:
   - NO Compton Spectra
   - NO Corrections
   - NO Calculations
• Self-Calibrating System
• Look straight at the X-Ray tube, record simultaneously the spectrum and the peak potential (kVp)
• The technology that went to Mars on the Pathfinder Mission is now available to Radiology!
• A must detector for every Radiology Department
• For Quality Assurance in Radiographic and Fluoroscopic Systems
• No Liquid Nitrogen

Design Objective
This detector system was designed with the objective of simultaneously measuring the X-Ray tube peak potential (kVp), and to characterize the mammographic X-Ray tube spectrum.

Significance of the Measurement
Both the tube spectrum and the peak potential (kVp) are important parameters affecting the image quality in film-screen and digital mammography.
Automatic selection of proper target/filter combination in modern mammography systems may be affected by improper kVp.
In conventional devices, the user depends on central laboratory calibration and has no easy way to calibrate the instrument during use.

Complete System Includes:
• Detector - XR-100T-CdTe
• Power Supply/Amplifier - PX2T
• Collimator Kit - EXVC
• MCA8000A Multichannel Analyzer - MCA8000A

All Solid State Design - - - No Liquid Nitrogen!!!

System Description
The XR-100T-CdTe is a high performance X-Ray and Gamma Ray detector mounted on a thermo-electric cooler (Peltier type) together with the input FET to the preamplifier. Monitored by an integrated circuit, these components are kept at -30° C and are enclosed in a hermetic package with a vacuum tight, light tight Beryllium window. Power and signal processing to the detector is provided by the PX2T in order to ensure quick, stable operation in less than one minute from power turn-on. The output pulse produced by the PX2T connects directly to the input of the Multichannel Analyzer MCA8000A "Pocket MCA."

Collimator Kit
Amptek has developed the EXVC Collimator Kit to collimate the primary X-ray beam. This system is comprised of the standard 1.5 inch extender box which slides inside a Collimator Housing. The Collimator Housing can accommodate up to two Tungsten collimator disks that are placed inside a bayonet holder in front of the detector. By selecting the appropriate Tungsten collimator disks, the user can reduce the incoming X-ray flux and allow the detector and electronics to process the X-ray spectrum. Seven different Tungsten collimator disks are provided with different size holes (ranging from 25 µm to 2,000 µm hole) in order to allow for a wide range of applications. The Collimator Housing is made out of stainless steel.

The kit includes:
• Stainless steel collimator housing
• Tripod and mounting plate
• Laser pointer
• 7 Tungsten (W) Collimator disks:
   - 1 mm thick with 25 µm hole
   - 1 mm thick with 50 µm hole
   - 2 mm thick with 100 µm hole
   - 2 mm thick with 200 µm hole
   - 2 mm thick with 400 µm hole
   - 2 mm thick with 1000 µm hole
   - 2 mm thick with 2000 µm hole

References
<sub>Matsumoto, Massao, et al. "Direct measurement of mammographic x-ray spectra using CdZnTe detector," Medical Physics 27 (7), July 2000. p. 1490.

Vedantham, Srinivasan, et al. "Mammographic imaging with a small CCD-based digital cassette: Physical characteristics of a clinical system," Medical Physics 27 (8), August 2000, p. 1832.

Vedantham, Srinivasan, et al. "Full breast digital mammography with an amorphous silicon-based flat panel detector: Physical characteristics of a clinical prototype," Medical Physics 27 (3), March 2000, p. 558.S.

Miyajima, "Thin CdTe detector in diagnostic x-ray spectroscopy," Medical Physics, Vol. 30 No. 5, May 2003.S.

Miyajima, K. Imagawa, M. Matsumoto, "An alignment method for mammographic X-ray spectroscopy under clinical conditions," The British Journal of Radiology, 75 (2002), 763-766. © 2002 The British Institute of Radiology Abstract: This paper describes an alignment method for mammographic X-ray spectroscopy under clinical conditions. A pinhole, a fluorescent screen, a laser device and the case for a detector are used for alignment of the focal spot, a collimator and a detector. The method determines the line between the focal spot and the point of interest in an X-ray field radiographically. The method allows alignment for both central axis and off-axis directions.

S. Aiello, et al. "FLUXEN portable equipment for direct X-ray spectra measurements," Nuclear Instruments & Methods in Physics Research, A 518 (2004) 389-390.

P. Baldelli, et al. "Development of a quasi-monochromatic source for mammography applications," Nuclear Instruments & Methods in Physics Research, A 518 (2004) 386-388.S.

Miyajima and K. Imagawa, "CdZnTe detector in mammographic x-ray spectroscopy," Physics in Medicine and Biology, 47 (2002) 3959-3972.

Medical X-Ray Detector Specifications and description in PDF format (56 k)</sub>