Tag: radioactivity

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MiWord of the Day Is… Xeroradiography!

Who hasn’t done some creative photocopying at some point in their lives? I certainly do NOT condone this type of activity (very naughty) but would you believe me if I were to tell you that for a long while mammography made use of photocopy technology? Yes, I realize this sounds a little funny. Let me explain.


In the 1970s medicine made the association between heavy exposure to radiation for TB and thyroid treatments and the appearance of breast cancer three decades later. A reevaluation of the effects of radiation ensued and a call for ways to minimize exposure to ionizing radiation was made to the industry.


One of the first to answer that call was the radiologist John Wolfe from Detroit Receiving Hospital who in 1966 reported on the advantages of coupling photocopy technology with mammography. Xerox corporation jumped on the idea and developed a commercial unit in 1971 and “xeroradiography” was born! Basically, film from traditional x-ray imaging (yes back then they still used film!) was replaced with a selenium coated aluminum plate that was prepared for the exposure by being electrically charged. The result was that only a short burst of radiation (shorter exposure time means lower dose of radiation) was required to produce a very high quality image.






These xerox mammograms dominated the industry for over 20 years until new technology was developed more recently that provided even finer images with even less radiation. Cool.




Now for the fun part (see the rules here), using Xeroradiography in a sentence by the end of the day:


Serious: Hey Bob, did you know that mammograms produced using xeroradiography were blue? 


Less serious: My friend Jane was scheduled for a mammography. Having heard of xeroradiography reading the MiVIP blog she decided to DIY at her office. Problem was the print kept coming out black and white instead of blue from the Xerox machine…




OK, watch the Copy Cat trailer to decompress (or not?!!!) and I’ll see you in the blogosphere…




Pascal Tyrrell

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MiWord of the Day Is… PET scan!

 

Peanuts. What a great story. The most popular and influential comic strip in history. Snoopy was my first stuffed animal growing up. He still lives with my parents. So what is a PET scan anyway? I don’t recall ever seeing the picture above in any of the Peanuts cartoon strips.





Positron emission tomography (PET) is somewhat of a special medical imaging modality in that it brings together two different technologies from different times. Let me explain. Back in the early 1930s, George Hevesy was a young Hungarian physicist who developed biologically safe and useful radioactive tracers that could be ingested or incorporated into the body in some way.  Physicians would then manually locate where these radioactive tracers had gone in the body by using a Geiger counter at first and then later using special cameras (Kuhl‘s photoscan) to produce a crude emission image. 



So, how do we get cool pictures like these ones?  Well we would have to wait another 25 years after the development of radioactive tracers by Hevesy for the start of construction of instruments able to not only detect these radioactive sources in the body but to produce tomographic pictures.


It won’t be until the mid 1970s that PET – as we know it today – would be born. Essentially, a patient receives a emissions scan (PET) and a CT (we talked about that here) or MRI (we talked about that here) scan at the same time. The two scans are then merged together thanks to highly specialized computers (see the pictures in the middle frames). Voila! PET. 



PET is both a medical and research tool. Most often used in clinical oncology (medical imaging of tumors and the search for metastases), it is also important in clinical diagnosis of certain diffuse brain diseases such Alzheimer’s disease and other types of dementia.


Relax your brain a little listening to Radioactive by Imagine Dragons and don’t forget the fun part (see the rules here), using PET scan in a sentence by the end of the day:

Serious: Hey Bob, did you know that much of the success of the PET scan is due to the development of the radiopharmaceutical FDG (deoxyglucose) that lead the way to the characterization of Parkinson’s and Huntington’s disease?

Less serious: I can’t believe they developed yet another PET scan. Wasn’t the CAT scan enough?

See you in the blogosphere,

Pascal Tyrrell