Saturday, October 26, 2013

dRs New Blog - FeedBurner Reply
 
Just needed to tell you that if you  subscribe to the blog again on the newly designed website, make sure you answer the email from FeedBurner that will come almost immediately.  Many of us didn't see it or it got spammed, but it needs to be replied to so that the site knows it has your correct email address.  If you have resigned up but don't get an email about the next blog post on November 1st, then FeedBurner didn't get it.
 
Thanks.
 
Dennis


 

Saturday, October 5, 2013


SPECIAL NOTICE         I HAVE A NEW WEBSITE              10/5/13

Hi Everyone,
 
I'm not sure if this notice went out to you about the new Website.

As of September 30th I have a completely remodeled website.  The Blog is now part of the actual site and not here on Blogspot.  This is all wonderful news except the RSS feed subscribers didn't come across from Google.  This means if you subscribed before and would still like to get the bi-monthly notices, you will have to go to my new site and subscribe one more time.  Sorry about that, but there was no getting the info from the Google folks.  The web address is exactly the same at digitalradiographysolutions.com

If you read the new blog I wrote for today on that site, it will explain almost all of the cool things the new site has that the old one didn't. 

So thanks for all your support in the past and I hope it continues into the future!!.

With Lots of Humble Gratitude,

Dennis

Monday, September 30, 2013


SPECIAL NOTICE         I HAVE A NEW WEBSITE              9/30/13

Hi Everyone,

As of September 30th I have a completely remodeled website.  The Blog is now part of the actual site and not here on Blogspot.  This is all wonderful news except the RSS feed subscribers didn't come across from Google.  This means if you subscribed before and would still like to get the bi-monthly notices, you will have to go to my new site and subscribe one more time.  Sorry about that, but there was no getting the info from the Google folks.  The web address is exactly the same at digitalradiographysolutions.com

If you read the new blog I wrote for today on that site, it will explain almost all of the cool things the new site has that the old one didn't. 

So thanks for all your support in the past and I hope it continues into the future!!.

With Lots of Humble Gratitude,

Dennis

Sunday, September 15, 2013


# 18                       Image Gently/Image Wisely                     9/15/13

Today I’d like to tell you a little bit about two wonderful organizations; Image Gently and Image Wisely.  Image Gently was created first, in 2007.  In one sentence, their goal is, “to change practice: to raise awareness of the opportunities to lower radiation dose in the imaging of children”.  A couple of years later it was realized that this goal was also very important for all the rest of our patient’s who are not pediatrics, so Image Wisely was created.

The four groups of professionals that make up Image Gently and Wisely are: Imaging Technologist’s, Imaging Physicians, Medical Physicists and Nuclear Medicine Tech’s.  As of today’s post, there are currently 20, 831 members of Image Gently and 18,825 members of Image Wisely.

I joined both organizations a few years ago as soon as I was introduced to them.  Their entire goal is for the imaging professional to give better patient care, and what is more important than that?  At the end of this post I have attached a copy of both the “pledges” that one would make if you decide to join.  They are from one of the last slides I present in my 6 and 8 hour talks.  I can guarantee you that NO ONE will EVER contact you or use your phone number or email address.  All they want is for you to believe in the pledge and try your best to conduct your professional life accordingly.  Also the totals of the members will increase, showing both the professionals and the patient’s that there really are a lot of us that truly believe in great patient care.

One of the really incredible things about the Image Gently site is the section they have for parents.  In it they can find well written, non technical descriptions of the scarier exams children sometimes have to go through.  These include; contrast enemas, UGI’s, VCUG’s, CT’s, interventional exams and Nuclear Medicine exams.

 I'll let the pledges speak for themselves.  If you agree with them, I would love to see you join us.  You can click here to get to Image Gently and her to get to Image Wisely.
 
 

Sunday, September 1, 2013


#17                         The 15% Rule and the Not So Famous Bowman’s 7 ½% Rule                              9/ 1/13

 

     I believe the 15% rule was figured out in the mid 50’s.  Of course this was back in the days of film/screen, but it still holds true today in the digital world.  
     The “Rule” stated that if you increase any given technique by adding 15% more kV the following film would have twice the density/opacity (which we will now just call opacity) as the original film.  And that’s all there is to the rule. 
     Now what most people have done with it is cut the mAs in half after they increased the kV 15%, but that’s now an addition to the 15% Rule (which we will now call the 15% Rule with mAs compensation).  And a great addition it is.  It was a way to change the technique but still end up in with basically the same opacity that you started with.  This is because when you increase the kV 15% the film was double the perfect opacity from what you wanted, but then by cutting the mAs in half you also cut the opacity in half thereby ending up right where you began but with a new technique.
     What must be mentioned here is from the many experiments I performed on both the 15 and 7 ½% Rules (I'll get to that one), the Exposure Index (EI) number stayed the same or was very close.  This means that after changing the techniques with either or both rules your EI number will still be correct!!
     There are really 2 main reasons why someone would do the 15% Rule with mAs compensation.  The first is to cut the patient dose.  To read more about this, please refer to Blog #12 from 6/15/2013 (How Low Can You Go?) where I explain that by increasing 15% more kV and cutting the mAs in half you can save your patient almost 33% of the Entrance Dose!!
     The second reason would be to cut the time for the exposure.  This is really only needed on portable machines that have a built in 100 mA station (which is most portables on the market).  100 mA means if your technique has 200 mAs then your exposure time will be 2 seconds, a 50 mAs exposure would be ½ a second and so on.  This usually happens when doing portable abdomens on a patient who is unable to follow breathing instructions and your exposure time is over ¼ of a second long.  I’ve always taught (even back in the film days) that an image taken out of the optimum kV range which is possibly or even definitely longer scale (greyer) than normal is always better than an image with motion.  In my opinion the only thing worse than motion is actually cutting off the anatomy.
     So now let’s quickly discuss the not so famous (yet!!) Bowman’s 7 ½% Rule.  As you will see it is simple and easy to do and quite often the perfect thing to use when changing techniques.  In a nutshell, all we are going to do is use half of the 15% Rule.  Since it’s easier to see it with actual techniques, let’s start with:

80 kV @ 40 mAs

92 kV @ 20 mAs = 15% Rule with mAs compensation

86 kV @ 30 mAs = 7 ½% Rule and cutting out a quarter of the mAs

     All that you need to do is first figure out what 15% of the kV is and what half the mAs would be and then just use half of each.  As you can see from the above example; 86 is exactly between 80 and 92 and 30 is exactly between 40 and 20.  With film all three of these techniques would have had the same basic opacity.  In the digital world (both CR and DR) the EI number will be the same.
      So why would use the 7 ½% Rule?  If you are still using low kV/high mAs techniques and now are willing to change, sometime doing the 15% Rule with mAs compensation will still not increase the kV high enough.  But if you did it all again the kV would now be too high, but just doing the 7 ½% Rule will be perfect.  Using the same example from before we see:

80 kV @ 40 mAs

92 kV @ 20 mAs = 15% Rule with mAs compensation

106 kV @ 10 mAs = 15% Rule with mAs compensation

99 kV @ 15 mAs = 7 ½% Rule and cutting out a quarter of the mAs

     So if you decide that you are unwilling to go above 100 kV for a particular shot, then using the 7 ½% Rule would be perfect as it takes you to 99 kV.  Of course this works with any starting kV or mAs and is applicable anytime you don’t want to increase your kV a full15%.
     If you have problems figuring out 15% of a number, I have a chart already made that shows 15% from 50-120 (see below).  To download this chart, go to: http://digitalradiographysolutions.com/files/29_kV%27s_and_the_15%25Rule.pdf   There also is a column that shows how much more opacity would be added if just 1 kV was added.  I have a whole discussion on that column in my full day lectures, but since that would take another page, for now I’ll just call it a day.


     kV
15%
1 kV =
50
7.5
13.30%
60
9
11.10%
70
10.5
9.50%
80
12
8.30%
90
13.5
7.40%
100
15
6.60%
110
16.5
6.00%
120
18
5.50%

Thursday, August 15, 2013

#16    Why Should You Increase the SID for Abdomen’s?               8/15/13

     For the first 10 years of my career (late 70’s, early 80’s) the SID for abdomen x-rays was 40” and that was written in stone.  I still remember the first new GE room we got at Watsonville hospital that had a 44” detente.  It seemed blasphemous that a company would think, much less do, such an outlandish thing.  Was nothing sacred?
     Then about 6 or 7 years ago one of our students told me that he had just come from a facility that did all of their supine abdomen x-rays  with the tube as high and table as low as possible and their upright’s were done at 72”.  Needless to say this seemed unbelievable to me but here was an x-ray department in my own area that had obviously been doing it for quite a while.  He explained that they did it because with the greater SID there was less divergence, so more anatomy was seen.
     Now that I knew this was even possible (and ethical), I asked our radiologist’s what they thought about it.  It turned out they loved the idea.  Since their entire job is to make a diagnosis with the information given to them, the more information they have to work with the better they like it.
     So I decided to do a simple experiment to see exactly how much more anatomy we would see when we increased the SID.  I took my abdomen phantom and exposed it at 40”, 50”, 60” and 72”. 
     As you can see in Figure 1,
at 40” the top of L1 is at the very top of the image and there's about a marker’s width below the ischial tuberosity at the bottom.  There is also just over a markers width on the sides. 
     In Figure 2, at 50”
we can now see about one third of a vertebra of room at the top and a marker and a half at the bottom and on the sides.
     In Figure 3,at 60”
we can now see about half of a vertebra at the top and a marker and three fourths on the bottom and sides.
     Finally in Figure 4,
at 72” we can now see a solid three fourths of a vertebra of room at the top and two markers on the bottom and sides.
     Since a vertebra is approximately one and a half inches in height, this means we gained at least two and a half inches of extra anatomy top to bottom and just under that on the sides.
     Plus there is a second reason to use a greater SID and this is to save the patient entrance dose.  Or at least I believe this is so.  I am almost positive I have read an article in the ASRT Journal that stated that an increased SID 40" to 4*"") would save a patient about 8% entrance dose.  Unfortunately when I went to look up that article for this posting I couldn't locate it.  If any of you know about this dose savings article, please write or call me and I'll let everyone know about it in my next blog or somewhere on my website.                     
     Whether there really is a dose savings or not, getting close to 3 more inches of anatomy on an upright abdomen surely is worth talking to your radiologist about this.   Just remember that the more SID you have the higher you need to center so that all the new anatomy you are showing is the upper abdomen and not the symphysis or below.
     If you are taking these images portably and need to technique it, remember that the mAs will need to be increased as the distance is increased.  If you want to know exactly what these changes are, please use the “exp-dist conversion” chart below (and located in the All Charts section of my website). 
 

Thursday, August 1, 2013

#15       My Version of the Perfect Exposure Index (EI) System         8/1/13

     The chart below is a system that Agfa has implemented with all of their new equipment.  It’s a three color system with green being “within range”, yellow being “slightly over or under exposed" and red being “significantly over or under exposed”.  I like that they took a stab at it, but think that they went the opposite of the AAPM in that their ranges are too wide open (see blog # 14 for the AAPM’s ranges).  The green (within range) goes from 15 to 60 mAs and 60 is quadruple 15.  I like that the yellow zone on the overexposed side is only from 60-90 mAs but don’t really like that one needs to be 4 times their perfect 30 mAs or 8 times their bottom of the green 15 mAs to get to a place that is deemed significantly overexposed.



   


     The chart above is the one I created to fix the problems I saw with both the AAPM and Agfa models.  I’ve used a 7 section/color system as I do not think it’s a great idea to have the same color for over and under exposures (for those radiographers who are just looking at the colors and not the numbers).  I’m not sure how difficult it would be to implement 7 colored light bulbs or filters in the control panel, but it would be the best set up and easiest to use and understand.
     The reasons for the 7 sections instead of Agfa’s 5 is the radiographer can really fine tune their technique skills and get a much better understanding about how an EI number that is noticeably off can still look perfect.  Keeping a nice tight range as to what is Very Good versus Within Range versus Significant and finally Excessive is the only way to truly combat Dose Creep.
     I’ve put the green/Very good from a perfect EIT to +60%, or 2 normal steps up in mAs.  From 61% to 100% (double the mAs) is the blue/Within Range.  From 101% to 199% (double to triple) we’re now in the yellow/Significant region and from 200% up we’re in the red/Excessive zone.
     If you remember from my last posting, I wrote about the Deviation Index (DI) number and that it quantifies how much the EI varies from the TEI.  So unless the EI number comes out perfect (identical to the EIT) there will be a minus or plus DI number.  It’s A great idea to have this EIT number, but what help is it if you now know that your exposure was a +4 but it doesn’t tell you how to fix the technique?


     So my colleague Carter Doupnick and I created the “How to Fix an Incorrect mAs” chart you see above.  To use it you start in the middle column with the mAs that was just used (either by manual technique or with the AEC).  Then you use the plus or minus rows depending on what the DI number was.  Let’s say it was a +4 and the mAs used was 63.  When you match them up you see that 25 mAs should have been used.
     I am hoping that every vendor starts using this “How to Fix an Incorrect mAs” chart as it really is the only way that a DI number will actually be useful to a radiographer.  With it, every repeat that needs to have the technique changed will be incredibly easy to accomplish.  It won’t matter one bit if you’re good or bad with math as all the calculations have already been done.  Plus all techs and students will be able to use this chart to see what would/could have been the perfect technique even though the image taken was perfectly diagnostic, but still over or under exposed.
     If you’re facility is using any of the newest equipment that displays the DI number and you’re wondering what to do with it, please contact me so I can set your department up with this chart and system.

 Link to Digital Radiography Solutions Websitedigitalradiographysolutions.com