The CARE bill (Consistency, Accuracy, Responsibility and Excellence in Medical Imaging and Radiation Therapy Act) is advancing in Congress... an article released October 14, 2009 states that "all medical imaging professionals to be state-certified under standards set by the secretary of the Department of Health and Human Services."
If you live in a State that does not currently require x-ray licensure to take radiographs, this may change soon. According to the article, the bill, if passed, would take effect in January, 2013, and would require any technologist performing x-ray, fluoroscopy, and ultrasound procedures to be licensed under state-specific guidelines.
There are those who oppose this change for whatever reason, but I think this is a good step in the ever-expanding quest to promote professionalism in our field. Considering situations like my last post I believe this has come at a crucial time. There will be opposition to this, of course. Many people have been trained "on the job" in chiropractor's offices, medical assistant positions, and in private doctors offices throughout states that do not currently require this formal training. Physicians who employ these individuals may have to pay more money to hire qualified professionals to take their places, at higher cost to them.
You can view the bill here... or log onto www.asrt.org to get updates on the latest news.
Friday, November 13, 2009
Friday, September 18, 2009
Update on CT Overexposure Court Case
If you were previously unaware of this case, there are additional articles linked at the bottom of this one, found on the "Aunt Minnie" website.
This is one reason why the level of professionalism and proper training for entering this field should be held in the highest of standards, not only in school, but throughout our careers after.
I remember training on a similar model when I did CT, and it took about 8 seconds to perform one axial slice, then an additional 8 seconds to reset itself to the original tube travel position. It was a DOS-based computer with very limited capabilities compared to what is out today. There was no audio recording telling the patient to hold their breath or when they could breathe. We had a microphone and had to count to eight every slice before verbally instructing the patient for each breath hold. An abdomen/pelvis scan would often take more than an hour because the tube would overheat on most patients once we got down to the pelvic bone, and each slice would take an exponentially longer wait-time before the heat unit overload would allow us to safely take the next slice. This was outdated equipment eight years ago when I used it, and I'm surprised to hear that it was still in use. Regardless, the technologist has the responsibility to maintain the guidelines of ALARA.
This is one reason why the level of professionalism and proper training for entering this field should be held in the highest of standards, not only in school, but throughout our careers after.
I remember training on a similar model when I did CT, and it took about 8 seconds to perform one axial slice, then an additional 8 seconds to reset itself to the original tube travel position. It was a DOS-based computer with very limited capabilities compared to what is out today. There was no audio recording telling the patient to hold their breath or when they could breathe. We had a microphone and had to count to eight every slice before verbally instructing the patient for each breath hold. An abdomen/pelvis scan would often take more than an hour because the tube would overheat on most patients once we got down to the pelvic bone, and each slice would take an exponentially longer wait-time before the heat unit overload would allow us to safely take the next slice. This was outdated equipment eight years ago when I used it, and I'm surprised to hear that it was still in use. Regardless, the technologist has the responsibility to maintain the guidelines of ALARA.
Saturday, July 11, 2009
Experaments with Scatter
We know that CR image plates are more responsive to scatter and background radiation than film/screen systems... so we decided to see exactly how sensitive they would be to an exposure within the x-ray room.
A phantom was set up on the tabletop to expose a lateral lumbar spine. We used 75 kVp, 200 mAs at a 40" SID. We did not actually expose an image plate for the lumbar spine, but we wanted to mainly focus on the scatter produced by that exposure.
So we measured 8 feet from the spine phantom and set up a 10x12 cassette vertically with a cassette holder. A hand phanotm was placed in front of the cassette and the exposure was made. The following image resulted on Kodak CR with an exposure index of 1190.
You can see that the scatter was enough to penetrate soft tissue and bone enough to see medulary canal.
We decided to re-create the experiment with the same spine phantom, but this time we placed a chest phantom upright next to a 14x17 cassette, approximately 6 feet away from the spine phantom at about the same height. We ended up with an exposure index of 980.
It was definitely enough to penetrate the lung fields, but may not have been enough to penetrate the shoulder or neck region. 6 feet is the minimum safe distance we should be on all portables... hopefully, this will make us think twice about wearing a lead apron when we shoot portables (especially on anatomy that requires a lot of technique).
As a side note, the chest image really allows us to visualize penumbra... or geometric unsharpness produced at the periphery of the anatomy. We know that the smaller the focal spot, the less the penumbra. We have essentially created a gigantic focal spot because the source of most of the radiation hitting the chest phantom was scattered from different points within the lumbar spine phantom on the table... approximately a 27cm focal spot size!
A phantom was set up on the tabletop to expose a lateral lumbar spine. We used 75 kVp, 200 mAs at a 40" SID. We did not actually expose an image plate for the lumbar spine, but we wanted to mainly focus on the scatter produced by that exposure.
So we measured 8 feet from the spine phantom and set up a 10x12 cassette vertically with a cassette holder. A hand phanotm was placed in front of the cassette and the exposure was made. The following image resulted on Kodak CR with an exposure index of 1190.
You can see that the scatter was enough to penetrate soft tissue and bone enough to see medulary canal.
We decided to re-create the experiment with the same spine phantom, but this time we placed a chest phantom upright next to a 14x17 cassette, approximately 6 feet away from the spine phantom at about the same height. We ended up with an exposure index of 980.
It was definitely enough to penetrate the lung fields, but may not have been enough to penetrate the shoulder or neck region. 6 feet is the minimum safe distance we should be on all portables... hopefully, this will make us think twice about wearing a lead apron when we shoot portables (especially on anatomy that requires a lot of technique).
As a side note, the chest image really allows us to visualize penumbra... or geometric unsharpness produced at the periphery of the anatomy. We know that the smaller the focal spot, the less the penumbra. We have essentially created a gigantic focal spot because the source of most of the radiation hitting the chest phantom was scattered from different points within the lumbar spine phantom on the table... approximately a 27cm focal spot size!
Wednesday, July 8, 2009
Semi-Auto Lab Experament
This week in our imaging lab, we decided to look into the EDR functions even further by performing some experaments on our phantom using the Semi-Auto option, which selects region 5 on the FUJI CR image plate. Our control image, shown first, came out exactly like you would expect it to having the tube, part and bucky aligned, and it was processed on the default "auto" setting (all images in this experament utilized a technique of 70 kVp 3 mAs and 40" SID in the table bucky):
Image #2 kept all of the same alignment, technical factors, and positioning, but we processed it on "semi-auto" to see if the image would come out better... in my opinion on this phantom, I didn't necessarily like it as much. The bony detail through the petrous ridges is lacking and it has somewhat of a longer scale of contrast - undesired if performing this view for sinuses. Note the slight change, yet acceptable S# differences between these first two exposures.
For exposure 3, we decided to keep the semi-auto setting, but we took the x-ray tube off of transverse detent so that everything was aligned except the tube. This is how the field light appeared over the phantom with the cassette alignment underneath:
As you can see with the resulting image, the S# is 3820, which is severely underexposed. The computer is attempting to adjust the density over region 5 on the image plate. Over half of region 5 lies outside the exposure field, which makes the computer think "there aren't many photons here, so it must be underexposed... I'll try to darken the image to compensate because I'm a super-smart computer." We know coputers aren't that smart, and the result is a very dark image over the small bit of anatomy we can see due to automatic rescaling, and it retains its very high S#.
For our 4th image, we kept it on semi-auto, but we started fresh with everything aligned... we then moved the phantom out of alignment. The tube and bucky were aligned but the skull was off-centered like so:
In this image, the S# is 50, which overexposed. The computer is attempting to adjust the density over region 5 on the image plate. Most of region 5 is exposed with the full technique appled without any absorption by the tissue of the phantom, which makes the computer think "there are too many photons here, so it must be overexposed... I'll try to lighten up the image to compensate because I'm a super-smart computer." Again, not smart, just playing by a set of rules and the result is a very light image over the small bit of anatomy we can see due to automatic rescaling, and it retains its very low S#.
We thought these errors were so interesting that we decided to try the alignment mishaps on the "auto" setting to see if it would be more forgiving, or if we would yield similar results. Image 5 was taken with the same misalignment of the x-ray tube that occurred in image 3, but on "auto." Below we see the S# slightly higher than the optimal range at 308, but certainly looking better than exposure 3.
And finally, we reproduced the off-centered patient as in exposure 4 on "auto" and produced a low S# of 50, but also looking better on the auto setting than on the semi-auto where field 5 was the main point of interest.
The lesson learned is that we must out-smart our computer software... be extremely careful with positioning and alignment when selecting any EDR option that will only form a histogram based on a selected region.
Image #2 kept all of the same alignment, technical factors, and positioning, but we processed it on "semi-auto" to see if the image would come out better... in my opinion on this phantom, I didn't necessarily like it as much. The bony detail through the petrous ridges is lacking and it has somewhat of a longer scale of contrast - undesired if performing this view for sinuses. Note the slight change, yet acceptable S# differences between these first two exposures.
For exposure 3, we decided to keep the semi-auto setting, but we took the x-ray tube off of transverse detent so that everything was aligned except the tube. This is how the field light appeared over the phantom with the cassette alignment underneath:
As you can see with the resulting image, the S# is 3820, which is severely underexposed. The computer is attempting to adjust the density over region 5 on the image plate. Over half of region 5 lies outside the exposure field, which makes the computer think "there aren't many photons here, so it must be underexposed... I'll try to darken the image to compensate because I'm a super-smart computer." We know coputers aren't that smart, and the result is a very dark image over the small bit of anatomy we can see due to automatic rescaling, and it retains its very high S#.
For our 4th image, we kept it on semi-auto, but we started fresh with everything aligned... we then moved the phantom out of alignment. The tube and bucky were aligned but the skull was off-centered like so:
In this image, the S# is 50, which overexposed. The computer is attempting to adjust the density over region 5 on the image plate. Most of region 5 is exposed with the full technique appled without any absorption by the tissue of the phantom, which makes the computer think "there are too many photons here, so it must be overexposed... I'll try to lighten up the image to compensate because I'm a super-smart computer." Again, not smart, just playing by a set of rules and the result is a very light image over the small bit of anatomy we can see due to automatic rescaling, and it retains its very low S#.
We thought these errors were so interesting that we decided to try the alignment mishaps on the "auto" setting to see if it would be more forgiving, or if we would yield similar results. Image 5 was taken with the same misalignment of the x-ray tube that occurred in image 3, but on "auto." Below we see the S# slightly higher than the optimal range at 308, but certainly looking better than exposure 3.
And finally, we reproduced the off-centered patient as in exposure 4 on "auto" and produced a low S# of 50, but also looking better on the auto setting than on the semi-auto where field 5 was the main point of interest.
The lesson learned is that we must out-smart our computer software... be extremely careful with positioning and alignment when selecting any EDR option that will only form a histogram based on a selected region.
Tuesday, June 30, 2009
CR Image Plate
With all of the new curriculum material being added to the Registry in the coming years, it is required for us to have good working knowledge of how the photostimulable phosphor plates work with CR cassettes. Most curriculums are encorporating this into study now, and I won't bother going into those details, but I would like to post about an observation I made when reading up on the topic and preparing for some lab sessions with my current students.
According to the Carlton and Addler textbook that our students are required to purchase, the active layer is the photostimulable phosphor layer, which is responsible for retaining a latent image after x-ray exposure. This happens when x-rays ionize the plate, releasing electrons to be collected by an "electron trap" in the conductive layer of the phosphor screen.
This image, taken from the FUJI website (an excellent source for information by the way), depicts the electrons collected in the trap, and representing a stored charge that is now our latent image.
During development of the cassette, a helium-neon laser (a really intense light source), sweeps the cassette during the forward motion of plate travel through the reader, and that charge is released in the form of light photons (following picture also from FUJI).
As you can see, there is a "light guide" which collects the visible light emitted from the plate and transfers it to a photomultiplier tube, which amplifies the light signal. Later it goes to an analog to digital converter to be interpreted into an electrical signal that the monitor can display as our radiograph at our QC station, and so on and so forth.
If you have ever opened one of the CR cassettes, even after a radiographic exposure has been made on it, you might notice that the room light does not fog the image plate. So knowing that an intense light (helium-neon laser) is used to release the charge on the plate during image processing, I wondered if I could reproduce that effect outside of the image processor myself.
Here's what I decided to do... I received two laser pens for my birthday recently (green in luminance) that my wife and I jokingly use to point out things when we watch TV, i.e., physical flaws possessed by contestants on the television show "The Bachelorette," crooked nostrils, stains on clothing, you get the picture (way beside the point, but fun).
I wondered if the laser pens were intense enough to cause a change in the radiographic density on the image plate.
First, I took an unexposed plate and removed it from the cassette and turned out the room lights. I thought "it's photostimulable, so what would happen if I simply shine my laser light on it? Would it emit a visible light? Would it produce a density on my developed image?" Uh... no. After trying this in an unexposed image plate, there was no visible light produced except what was caused by my own laser pen, and no visible density was recorded on the developed image after processing.
So next, I tried a relatively small exposure (about a finger technique) on a cassette, then tried removing the image plate from the cassette to see if I could observe visible light when shining my pen on it. I was not able to perceive visible light when I tried this... why? Probably because the light would be very dim, and the brightness of my laser pen interfered with any that I might have been able to see. There is, after all, a photomultiplier tube which enhances the light emitted by the screen inside the reader. However, when I developed the image, this was the result:
It appears as if my laser light, in fact did have enough intensity to release the trapped electrons from their place in the conductive band. We have an area of decreased density on the image where the my laser pen interacted with the plate and released the electrons. The reader was not able to detect any light emitted from these regions with the helium-neon laser because the electrons had already been released, and no density was provided in that area.
Does this help us in our formation of the image? Probably not, but it does help to understand the process of turning our latent image into the manifest image using CR. I highly reccommend purchasing a laser-pen, even if you never use it for radiography-related purposes, it's still good fun for television. A special shout to my wife - thanks for my laser-pens!
According to the Carlton and Addler textbook that our students are required to purchase, the active layer is the photostimulable phosphor layer, which is responsible for retaining a latent image after x-ray exposure. This happens when x-rays ionize the plate, releasing electrons to be collected by an "electron trap" in the conductive layer of the phosphor screen.
This image, taken from the FUJI website (an excellent source for information by the way), depicts the electrons collected in the trap, and representing a stored charge that is now our latent image.
During development of the cassette, a helium-neon laser (a really intense light source), sweeps the cassette during the forward motion of plate travel through the reader, and that charge is released in the form of light photons (following picture also from FUJI).
As you can see, there is a "light guide" which collects the visible light emitted from the plate and transfers it to a photomultiplier tube, which amplifies the light signal. Later it goes to an analog to digital converter to be interpreted into an electrical signal that the monitor can display as our radiograph at our QC station, and so on and so forth.
If you have ever opened one of the CR cassettes, even after a radiographic exposure has been made on it, you might notice that the room light does not fog the image plate. So knowing that an intense light (helium-neon laser) is used to release the charge on the plate during image processing, I wondered if I could reproduce that effect outside of the image processor myself.
Here's what I decided to do... I received two laser pens for my birthday recently (green in luminance) that my wife and I jokingly use to point out things when we watch TV, i.e., physical flaws possessed by contestants on the television show "The Bachelorette," crooked nostrils, stains on clothing, you get the picture (way beside the point, but fun).
I wondered if the laser pens were intense enough to cause a change in the radiographic density on the image plate.
First, I took an unexposed plate and removed it from the cassette and turned out the room lights. I thought "it's photostimulable, so what would happen if I simply shine my laser light on it? Would it emit a visible light? Would it produce a density on my developed image?" Uh... no. After trying this in an unexposed image plate, there was no visible light produced except what was caused by my own laser pen, and no visible density was recorded on the developed image after processing.
So next, I tried a relatively small exposure (about a finger technique) on a cassette, then tried removing the image plate from the cassette to see if I could observe visible light when shining my pen on it. I was not able to perceive visible light when I tried this... why? Probably because the light would be very dim, and the brightness of my laser pen interfered with any that I might have been able to see. There is, after all, a photomultiplier tube which enhances the light emitted by the screen inside the reader. However, when I developed the image, this was the result:
It appears as if my laser light, in fact did have enough intensity to release the trapped electrons from their place in the conductive band. We have an area of decreased density on the image where the my laser pen interacted with the plate and released the electrons. The reader was not able to detect any light emitted from these regions with the helium-neon laser because the electrons had already been released, and no density was provided in that area.
Does this help us in our formation of the image? Probably not, but it does help to understand the process of turning our latent image into the manifest image using CR. I highly reccommend purchasing a laser-pen, even if you never use it for radiography-related purposes, it's still good fun for television. A special shout to my wife - thanks for my laser-pens!
Wednesday, June 10, 2009
Semi-X
Semi-X is one of the EDR options that can be selected on FUJI CR prior to image processing. You can select this after you have prescribed a specific projection/view, but prior to scanning the barcode for the cassette ID. In this example, I attempted an axillary view of the shoulder on our phantom in the lab:
When selecting the Semi-X option, you will be given a choice of cells (1-9) as seen on the prior post, but it is crucial to properly orient your cassette, and remember how your numbered regions correspond to the green orientation bar.
For my phantom images, I decided to perform a left axillary shoulder, so I placed my green orientation bar (on a crosswise 10 x 12 cassette) closest to the "patient's" neck. This changes the layout of my numbered regions as shown:
I decided to expose my first image without the use of the Semi-X option... the following image was taken on the default "Auto" setting, which forms a histogram based on either the entire image plate, or whatever pixels lie within the recognized collimated field. It is important to note that sometimes on actual patients, the greater the soft tissue density around the patient's shoulder, the more scatter will be produced... especially in comparison with my images from a phantom. The scatter could lead to software being unable to recognize the collimated borders, thus the inclusion of more data in your histogram than what was actually in the collimated field.
This image was shot at 60 kVp, 4.2 mAs, and the resulting S# was 280 on the Auto setting:
My second image utilized identical exposure factors, but I selected the Semi-X option and chose field #7, which should be aligned with the humeral head. This gave me a much more desirable image with an S# of 159, and much better contrast with less density than on the Auto setting:
My third image utilized identical exposure factors again, but I selected the Semi-X option and chose field #4, which should be aligned with the surgical neck and proximal humerus. This gave me an even better image with an S# of 132, and even more contrast with less slightly less density than image 2:
And just for kicks, I decided to perform one more image with the same exposure factors and simulated a common error - improper selection of the numbered region. This error would occur with either improper cassette orientation, or if there was any confusion of where the green orientation bar was located. The following was set to field 6, which is outside the original collimated border, with an S# of 2968. As you can tell, the software is attempting to equalize the histogram for that region on the cassette, allowing us to see the mottle pattern of the scatter, but preventing us from visualizing the anatomy itself... it's telling us that we're severely underexposed - and that would be true if we are trying to visualize something over #6.
All in all, this is a valuable tool to utilize with exams like axillary shoulder, cross-table hip, perhaps trauma and OR views and anything which would prevent you from placing the anatomy of interest in the center of the cassette. Just remember to always know where your green orientation bar is, and how the numbered regions lie in relationship to it.
When selecting the Semi-X option, you will be given a choice of cells (1-9) as seen on the prior post, but it is crucial to properly orient your cassette, and remember how your numbered regions correspond to the green orientation bar.
For my phantom images, I decided to perform a left axillary shoulder, so I placed my green orientation bar (on a crosswise 10 x 12 cassette) closest to the "patient's" neck. This changes the layout of my numbered regions as shown:
I decided to expose my first image without the use of the Semi-X option... the following image was taken on the default "Auto" setting, which forms a histogram based on either the entire image plate, or whatever pixels lie within the recognized collimated field. It is important to note that sometimes on actual patients, the greater the soft tissue density around the patient's shoulder, the more scatter will be produced... especially in comparison with my images from a phantom. The scatter could lead to software being unable to recognize the collimated borders, thus the inclusion of more data in your histogram than what was actually in the collimated field.
This image was shot at 60 kVp, 4.2 mAs, and the resulting S# was 280 on the Auto setting:
My second image utilized identical exposure factors, but I selected the Semi-X option and chose field #7, which should be aligned with the humeral head. This gave me a much more desirable image with an S# of 159, and much better contrast with less density than on the Auto setting:
My third image utilized identical exposure factors again, but I selected the Semi-X option and chose field #4, which should be aligned with the surgical neck and proximal humerus. This gave me an even better image with an S# of 132, and even more contrast with less slightly less density than image 2:
And just for kicks, I decided to perform one more image with the same exposure factors and simulated a common error - improper selection of the numbered region. This error would occur with either improper cassette orientation, or if there was any confusion of where the green orientation bar was located. The following was set to field 6, which is outside the original collimated border, with an S# of 2968. As you can tell, the software is attempting to equalize the histogram for that region on the cassette, allowing us to see the mottle pattern of the scatter, but preventing us from visualizing the anatomy itself... it's telling us that we're severely underexposed - and that would be true if we are trying to visualize something over #6.
All in all, this is a valuable tool to utilize with exams like axillary shoulder, cross-table hip, perhaps trauma and OR views and anything which would prevent you from placing the anatomy of interest in the center of the cassette. Just remember to always know where your green orientation bar is, and how the numbered regions lie in relationship to it.
Sunday, June 7, 2009
Exposure Data Recognition
If you've ever wondered what the "EDR" button on your FUJI CR system is for, it stands for "Exposure Data Recognition." In order to properly utilize this unique feature, we need to know how it works.
FUJI CR plates have 9 sections on them divided equally. If you've ever noticed the green horizontal orientation bar, that should be either placed at the head of your patient (for lengthwise exposures) or at the patient's right (for crosswise exposures). This is important to remember when using the EDR feature.
When using the EDR option, it can only be applied before image processing, and additionally, needs to be selected prior to scanning your cassette bar code associating it with the desired view. The EDR has four modes:
AUTOMATIC
SEMI-AUTO
SEMI-X
FIXED
Automatic - this is the default setting on most IIP's. This mode will sample the entire cassette if it is exposed in its entirety. It also, however, should detect collimated fields and if collimated properly, will only include the exposed areas inside that field as part of the "values of interest" in the histogram (see "Anatomy of a Histogram").
Semi-Auto - this mode will only take a sample from the central partition of the cassette (#5 in the above diagram). As you can suspect, positioning is key when selecting this option, but should be familiar to you if you are comfortable with utilizing the center cell with AEC.
Semi-X - allows you to select one of the nine partitions of the IP. Depending on the anatomical part or projection you are attempting to perform, selection of the proper partition is crucial, as is the need for proper cassette orientation.
Fixed - for those of us who were once comfortable utilizing film/screen combination radiography, this may just be an equally comfortable option to choose. Instead of a histogram and software equalization, whatever technical factors you select will be represented by the density and contrast on your image. A double in mAs will actually be a double in density, and you have the option of choosing a speed class (which is representative of the film/screen speed combo with conventional radiography).
This can be a lot to swallow or to know how to use appropriately... more specific posts for each option to come!
FUJI CR plates have 9 sections on them divided equally. If you've ever noticed the green horizontal orientation bar, that should be either placed at the head of your patient (for lengthwise exposures) or at the patient's right (for crosswise exposures). This is important to remember when using the EDR feature.
When using the EDR option, it can only be applied before image processing, and additionally, needs to be selected prior to scanning your cassette bar code associating it with the desired view. The EDR has four modes:
AUTOMATIC
SEMI-AUTO
SEMI-X
FIXED
Automatic - this is the default setting on most IIP's. This mode will sample the entire cassette if it is exposed in its entirety. It also, however, should detect collimated fields and if collimated properly, will only include the exposed areas inside that field as part of the "values of interest" in the histogram (see "Anatomy of a Histogram").
Semi-Auto - this mode will only take a sample from the central partition of the cassette (#5 in the above diagram). As you can suspect, positioning is key when selecting this option, but should be familiar to you if you are comfortable with utilizing the center cell with AEC.
Semi-X - allows you to select one of the nine partitions of the IP. Depending on the anatomical part or projection you are attempting to perform, selection of the proper partition is crucial, as is the need for proper cassette orientation.
Fixed - for those of us who were once comfortable utilizing film/screen combination radiography, this may just be an equally comfortable option to choose. Instead of a histogram and software equalization, whatever technical factors you select will be represented by the density and contrast on your image. A double in mAs will actually be a double in density, and you have the option of choosing a speed class (which is representative of the film/screen speed combo with conventional radiography).
This can be a lot to swallow or to know how to use appropriately... more specific posts for each option to come!
Thursday, February 5, 2009
Hiatus
I want to apologize to everyone following my blog... it has been quite a while since I've had the opportunity to post anything, but I'm planning on diving in full-force again within the next couple of months. Still have a lot of visitors, and I've had many requests for postings on some rather good questions, so I'll have plenty of material! Thanks for following along after the long silence!
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