So what the heck is ionizing radiation? Well consider the following conundrum about x-rays. They can:
1- cause cancer
2- be used to detect cancer.
3- be used to treat cancer.
Whaaat? How does that work? We use the term ionizing when the radiation has sufficient energy to detach electrons from molecules causing them to become chemically reactive ions.
The name atom means “indivisable” and are incredibly small. They are made up of protons, neutrons, and electrons with about 99.9% of its mass concentrated in the nucleus that holds a positive charge. A surrounding negatively charged cloud of electrons makes up the difference and the atom stays together due to the attraction between the two.
OK, so here is the rub: if an atom gains or loses an electron it becomes an ion and generally results in a very chemically reactive substance. This process to produce an ion can be achieved by many ways but one of the most important is electromagnetic radiation (we’ve talked about this already here). Radioactive materials such as radium emit ionizing radiation as does x-ray tubes. There is even such a thing as cosmic radiation (Yup, we talked about that here!).
Now x-rays produce photons which are the same particles that make up visible light but at a much shorter wavelength and higher energy. When they penetrate through a solid object they will most often simply pass through. However, if they pass by close enough to an electron they can transfer their energy and in the process knock it out orbit producing an ion. Also, the more dense the object the more often the photons are blocked from travelling through resulting in a differential effect on a film or sensor placed on the opposite side. This is how we are able to see inside the body using x-rays.
The problem about ionizing radiation is that the resulting chemically reactive ions can result in DNA damage. Often the cell can repair itself resulting in no permanent damage. Other times, however, permanent damage occurs and can result in cell death (a good thing if they are cancerous cells) or DNA mutations that can in turn lead to the promotion of cancer – bummer.
Now on to using ionizing in a sentence today (not sure about the rules? See here):
Serious example – Bob, don’t stand too close to the x-ray machine. You wouldn’t want to be exposed to ionizing radiation that could damage the DNA in your cells…
Less serious – You wouldn’t believe what happened to me at work today! I was at the photocopy machine getting ready to change the toner cartridge and Bill from sales said:”Let me do that for you, Honey”. He is so ionizing or patronizing or whatever. He makes me mad…
Listen to Just Because by Raygun to get ready for the weekend and I’ll see you back in the blogosphere soon.
Pascal Tyrrell
MiWord of the Day Is Something to “Bragg” About…
OK who hasn’t made rock candy as a kid? No? Give it a try. Maybe you have a little brother or sister you can impress. All you need is a super saturated solution of sugar, a surface for crystal nucleation (string), and lots of time…
Now what if you were to apply this technique to obtain crystals of DNA? I don’t suggest that you eat it as a treat but you could possibly try X-ray crystallography.
The challenge is that DNA, unlike proteins, is an exceedingly large molecule which does not lend itself to crystallisation. The result is a highly viscous suspension of spiderweb-like filaments. However, it is this very suspension that the DNA molecules were deduced to be neatly aligned alongside one another by studying the X-ray diffraction patterns. This initial challenge was successfully overcome by Rosalind Franklin. Her hard work then laid the ground work for Watson and Crick to piece together the puzzle of DNA structure (winning the 1962 Nobel Prize along with Wilkins).
Now the x-ray crystallography imaging technique is no pic-nic! It was first described by the Australian father-and-son duo William Henry Bragg and William Lawrence Bragg. Essentially x-rays are projected onto a crystalline solid and when analyzing the diffraction patterns it is possible to determine how its molecular atoms are positioned in relation to one another. This is due to x-rays having very short wave-lengths (see x-rays in the blog) and the mathematical analysis of predictable diffraction from the three dimensional structure of the crystal. It was Lawrence Bragg who developed the equation to describe this diffraction and is now known as Bragg’s Law. He and his father won the Nobel Prize for this work in 1915.
I used to listen to New Order back in the day and they are still singing (and dancing?) with a more recent release of Crystal by New Order. So, listen to the song while making rock candy and maybe you too will come up with a brilliant idea worthy of a Nobel Prize by the time the crystals are big enough to eat.
Now if you remember the rules:
1- I introduce and discuss a word.
2- You have to use the word in a sentence by the end of the day. No need to use it in the correct context – actually out of context is more fun and elicits a more entertaining response!
Today, we have to use “Bragg” in a sentence. Here are two examples to help you along:
MiWord of the Day is… Supernova!
So, what does medical imaging have to do with a Supernova? Well in the B-movie – Supernova a deep space medical ship responds to a distress signal from a nearby mining planet and gets too close to a Red Supergiant ready to go Supernova. Is your geek alert tingling?
Well, believe it or not Supernovas are explosions of giant stars. Nuclear fusion produces iron in the cores of these stars. Such dense matter at the core creates a tendency for the star to collapse on itself due to gravitational pull. This is kept in check by the massive amounts of energy the star is constantly releasing. But what happens when the star starts to run out of fuel? Yup, you guessed it. It collapses on itself and implodes. As the star rushes inwards, protons and electrons combine to produce neutrons that in turn collide with the core and produce a crazy big explosion. This sudden release of energy is accompanied by the production of x-rays. Yes, I am serious. What is left behind of the exploded star is either a neutron star or a black hole depending on the mass of the remains.
So, a supernova is essentially a giant x-ray machine? Maybe not. However, by studying these cosmic x-rays astronomers are able to help describe the structure of the universe (not Castle Greyskull). Cool.
Question for you: should we be concerned with being exposed to cosmic x-rays? No. Cosmic x-rays are pretty much completely filtered out by our atmosphere by the time they get to the surface. So, how do astronomers get readings? Good question. By placing their recording instruments on satellites and spacecraft, of course!
Now on to using supernova in a sentence today:
Serious example – So did you catch the last supernova in our galaxy? Happened about 400 years ago. No? The next one should be soon as it is overdue by about 300 years.
Less serious – Growing up I always loved the Chevy Nova SS. Especially when it was customized. It surely was a super Nova…
Enjoy Ray LaMontagne – Supernova to recover from today’s post and I’ll see you in the blogosphere.
Pascal Tyrrell
The Importance of Research
There’s more to the field of medical imaging than a bunch of stuffy radiologists huddled around a couple of monitors. As I mentioned before in my previous post about the history of the imaging technique, the field has undergone a rapid technological advancement in the past century or so, improving the clinical model of visualization. But let’s take a step back from all the scientific stuff for a brief second and look at these developments in a
slightly different light.
The SparkNotes illustrated version of this post |
could go a long way. Who knows, you may find yourself presenting your findings at a research symposium, complete with nifty results and statistics to showcase your efforts.
A Crash Course in Medical Imaging
Oddly enough, there’s been a surprising lack of content about medical imaging on a blog with medical imaging in its title. So in order to fill that void, I’ll be providing a brief history on the development of the clinical technique used to visualize the human body.
The advent of medical imaging dates all the way back to 1895, following the discovery of X-rays by the German physicist, Wilhelm Conrad Roentgen. The first X-ray picture was then produced, detailing the skeletal composition of his wife’s left hand. However, the actual quality of this imaging process was still very primitive, only allowing for the visualization of bones or foreign objects.
Much to Dr. Roentgen’s pleasure, Mrs. Roentgen had not discarded her wedding ring |
- Ultrasound – Uses sound waves that are able to penetrate cellular tissue. Once they reflect off the body’s internal organs, the vibrations generate an electrical pulse which can then be reconstructed into an image.
- PET-CT Scan – Positron emission tomography (PET) uses compounds that emit positrons when they decay rather than gamma rays. It is now combined with a computed tomography (CT) device to generate a high-resolution image displaying sectioned layers of the scanned area.
- MRI – A Magnetic Resonance Imaging scanner runs a strong magnetic field through the body, aligning hydrogen protons. As the protons return to their original position in the atom, they generate radio waves, which are then picked up by the scanner and used to create an image based on signal strength.
Fast-forward to present day and over 70 million CT scans, 30 million MRI scans and 2 billion X-rays have been performed worldwide! The field of medical imaging is still growing by the day, with ongoing research leading to new developments.
Thanks for reading,