Density Maintenance Formula

I just didn't feel like that last video was complete after reading the original blog post it was meant to supplement, so I just had to go ahead and record the second example problem solution here:

Video Tutorial on Inverse Square Law

This video is using samples from an earlier blog post where my images mysteriously disappeared... I have replaced the images as well as created this video with additional explanations to supplement the original blog post:

Recognizing Motion on Lateral Chest Exams

One of our students brought this to my attention today, and I thought it would be a great example to share here.  The first image was the lateral chest view that I was asked to look at.  The technical factors used were 120 kVp, 32 mAs (320 mA at 0.1 sec) which produced an S# of 459:

Let's zoom in to the lower lungs and diaphragm:

This is one of the reasons it is good to magnify your images (if possible) when you QC your work.  You can tell that there is motion blur in the lung markings, lower ribs, and the diaphragm.  We agreed to repeat the image and we made some changes to the technical factors.  We decided to use 130 kVp at 32 mAs and change the mA and time stations (640 mA at 0.05 sec) which produced an S# of 373.  Here is image 2:

It is obvious that the patient had a larger breath in this time, and we are starting to see more density through the lung bases.  Even without zooming, you can see a large improvement in visualization of lung detail, ribs and diaphragm.  I'm going to window/level adjust and zoom in to compare to the prior zoomed image:

The difference is clearly noted with this magnified image.  Lung markings have clear, crisp detail, as well as well defined diaphragm margins and ribs.  You even notice far less visualization of the thoracic spine - another great example of why we do a breathing technique for T-spine.

I know that it doesn't take long to spot this after a couple of years experience as a technologist, but I have often heard students who say they have difficulty spotting motion on lateral chests.  This is a great example of how motion normally appears - little or no motion toward the apices and motion more exaggerated toward the bases.  Make sure to watch your patients' breathing and keep those time stations low!

New YouTube Channel

I'm excited to announce that I will be starting to post videos here via YouTube.  I only have one as of today, but there will be more to come very soon.  Please take a moment to subscribe to my channel.  I'm also taking suggestions for topics if you have anything you would like to see.  Please keep in mind that I am not planning on placing an entire x-ray program's worth of material here, but I would like to keep it to possibly clarifications of those topics, real-world examples of specific areas in your program, and/or advanced imaging topics - things you may learn after you graduate and obtain more experience.

That being said... my first video is a quick image critique of a portable chest x-ray (note - if you go to my YouTube channel, TopicsInRadiography, you can see the image at full size with much better detail):

How Will Healthcare Reform Affect Us?

To answer this with the information we have available to us right now... I don't know.  Nobody really knows because there is no definitive information about our direction, and it's ever-changing politics and strategies for dealing with it keep us on our toes, nervous and sweating bullets.  

What do we know about issues affecting us as Radiographers?  Medicare reimbursement is expected to decrease, followed by insurance coverage that will follow suit based on what Medicare is doing.  In other words, we will be expected to perform the same job, if not an increase in volume with our aging population, with fewer financial resources.  In order to stay ahead of the wake of financial burden, we are going to be asked to reduce cost... by means of supplies, labor, and waste while improving productivity and efficiency... not to mention the dependence on patient satisfaction for maximum reimbursement.  Quite the task!

I wanted to post this topic because I'm looking for interaction with you.  What is your hospital or health care system doing to plan for this?  Do they have a plan?  Have they begun any changes in practice?  My employer has some ground-breaking initiatives on this side of the country that are measurably making improvements in preparation for these cost-cutting requirements.  It is encouraging, but there is still work to do.  I encourage participation from all levels of the organizational flow chart as we are sometimes blind to perspectives above and below us.  What are your thoughts? 

Exposure Indicators

The current use of CR image plate technology is expanding at a rate that makes it difficult for seasoned technologists to keep up with.  Since radiography programs are now including more digital radiography curriculum, there seems to be a gap between the knowledge that new grads have about these systems, and the knowledge that experienced technologists have.  Some have attended CEU training, or courses that have kept information current, but there is a large population that have not, and who need that gap bridged.  I just wanted to write a quick post about three of the different types of exposure indicators that CR systems are currently using today... if there are other ones not posted here, I personally do not know about them, and would appreciate any info that any readers are willing to share!

Sensitivity Number (S#)

This is probably the most familiar one.  A typical optimum range might be from 200 - 400, although, with all of these examples, every hospital will have a different acceptable range for different exams.  Radiographic density and Sensitivity Number have an inversely proportional relationship.  If I double my mAs, my S# will decrease by 1/2 its original value.  Conversely, if I 1/2 my mAs, my S# will double.

Exposure Index (EI)

A typical optimum range for Exposure Index might be 1700 - 2000.  There is a direct, but not proportional relationship between Exposure Index and radiographic density.  For every double in mAs, the EI should increase about 300.  Every time you 1/2 your mAs, it should reduce the EI by 300.

Log Mean Exposure (LgM or LME)

A typical optimum range for Log Mean Exposure is around 1.9 - 2.1.  This one closely resembles the H&D curve representation of log relative exposure in the x-axis.  There is a direct, but not proportional relationship between LME and radiographic density.  For every double in mAs, the LME will increase by 0.3.  Every time the mAs is cut in 1/2, the LME is reduced by 0.3.

Knowing how to correct for insufficiencies in technical factors is the first step to producing diagnostic images using CR/DR systems.  Hopefully, we can all help each other to understand these principles and continue the efforts to improve quality and radiation protection standards.

WikiRadiography

I would really like to see more people getting involved in this site:

http://www.wikiradiography.com/

There are resources from all over the world, discussion forums, images and lots of resources for anything related to Radiography.