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 Your Guide to Medical Imaging Equipment

Enjoy these tips, tricks and insights that answer 100's of questions we've received from radiology and imaging professionals that need help buying, selling, servicing and maintaining their medical imaging equipment: MRI, CT, C-Arm, Digital X-ray, PET/CT and Women's Health. We extend the life of imaging equipment so that healthcare providers worldwide can extend the lives of patients. This is why we answer your imaging equipment questions.

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Digital Mammography Detectors Compared: Cesium Iodide vs. Selenium

Posted by Jordan Batterbee

Jul 18, 2013 3:11:00 PM

:: 1 minute read ::

Digital Mammo Cesium vs. SeleniumDigital technology in general represents a step forward in mammography image quality from analog systems. Even so, there is a spectrum of image resolution levels within the digital set.

One determining factor in resolution is the chemical composition of the detector. Two of the most commonly used compounds in digital mammography are cesium iodide (CsI) and amorphous selenium (α-Se). Each of these compounds is used in one of two image capture methods: indirect and direct X-ray conversion.

Indirect Conversion

Some earlier models, such as the GE 2000D or Fischer SenoScan use indirect flat panel detectors made with cesium iodide (CsI). In these detectors, X-rays are converted in a two-step process. X-Ray energy is collected by the CsI and converted into light. The light photons are then converted to electronic signals by a photodiode array. This process is less efficient and results in some light scatter during conversion. This, in turn, can reduce resolution.

Direct Conversion

Later systems like the Hologic Selenia or Siemens Novation use direct flat panel detectors made with amorphous selenium (α-Se). In these detectors, X-rays are converted in a one-step process. The layer of α Se in the detector absorbs the X-ray energy and converts it to an electronic signal directly (hence the name). Based on the efficiency of direct conversion and its elimination of light scatter, α-Se detectors are able to offer higher image resolution. The disadvantage of direct conversion systems is their price. The novelty of the technology does push α Se-based systems into a higher price bracket.


In the end, if a system is FDA-approved for use, it is capable of producing diagnostic-quality images. Digital mammography systems using indirect conversion detectors are reliable, affordable, and still used commonly. However, better image quality reduces the likelihood of repeat scans and false positives. If your budget allows for it, you may want to consider purchasing a system on the higher end of the image quality spectrum.


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Written by Jordan Batterbee

author of blog post

Jordan Batterbee is the SEO Copywriter at Block Imaging. He loves to research, write, and help others get clear, concise, and (hopefully) fun answers to their medical imaging questions.

Topics: Buying Imaging Equipment, Mammography

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