Imablog Perspectives of a Canadian in the Old/Deep/New/Geographic South: This is where I ramble on about nothing in particular and post a few nice pictures.

The Boards

All across the country, 4th year radiology residents are cramming and doing their last minute reviews for the ABR board exams coming up next week. And then after that they will come back, work a couple more weeks, pack up their stuff (if they haven't already) and head off to whatever places they have lined up jobs or fellowships at. And July 1, a new class of residents starts. Wash, rinse and epeat 12 months later.

This year I'm seeing my 5th class of residents head off from here to start off their careers.

Good luck residents. I hope you remember at least some of the physics I've been trying to teach you over the past few years!

The Sith are here! The Sith are here!

Finally saw the last installment of Star Wars last night. It was definitely much cooler than the previous two (way way better than Phantom Menace). I think this prequel series could have been much better without Episode 1, starting the prequel trilogy with Attack of the Clones and with more development of Skywalker's corruption to the dark side, expanding Revenge of the Sith into two movies. It just happened way to fast I think. I mean really, one minute he's full of anguish over watching Siddious throwing Windu out the window, and the next minute he's kneeling at Siddious' feet pledging his loyalty. I suppose you could say that Siddious was taking advantage of Skywalker's anguish and exerting some of his mind control powers and to me parts of that scene made me think this might have been happening. Still, Skywalker turning to the Dark Side needed a little more development and drama I think. And why didn't the Jedi Council do more to intervene when Yoda saw Skywalker heading to the Dark Side? Granted if they had, that probably would have ruined the story. But for all the talk of Skywalker being the 'Chosen One', the Jedi Council didn't really do much to prevent his slide to the Dark Side.

FX were very cool, and lots of good light saber action. Would have liked to see more wide shots and fewer closeups of Samuel Jackson in the Windu/Siddious battle

7/10 overall, and 10/10 compared to the previous two installments.

Ice junkie

I have a dog that loves ice. Absolutely loves it. If I could make teeny tiny ice cubes I could use them as very effective training treats. Crack the freezer and she comes running from wherever she is, sits down so hard she makes a thump and waits patiently for a treasured ice cube.

If she gets one, she's happy as a clam chomping and chasing it around the kitchen. She picks it up in her mouth, chews it a bit until her mouth gets too cold and then drops it. Licks it a bit, grabs it again and repeats. Funny to watch.

If she doesn't get one, she has this sad disappointed look on her face and then trots away with you as you walk away.

From what I've read, this isn't terribly abnormal for Labs, and there seem to be a lot of Lab owners out there who's dogs love ice cubes.

5 months old last week, and weighed in yesterday at 48 pounds. I need to take more pictures of her.

2 CeilingFan objects done, 1 more to go

Successfully managed to hang two more ceiling fans without serious injury or damage to the house. Now just one more ceiling fan to go up in the back porch and then on to the next project: installing window blinds in the office.

Just one of the many things that was accomplished this weekend, including spending a whole lotta money on House Stuff. Then going back, returning some House Stuff because it wasn't the Right Stuff, then buying even More House Stuff. So now most all the windows have something covering them, and all the rooms have fans.

So now with our left-over house money rapidly dwindling, we need to re-prioritize a few things. Fencing, hurricane shutters or plywood, grill, curtains, garage storage/shelving, lawn mower. It's a never-ending list. With the storm season starting to gear up, plywood for the windows is the top priority for this year. Hurricane shutters will have to come later because they're pretty pricey. The rest are still up for discussion.

Light fixtures and bulbs

Anybody want one of these outdoor ceiling mount light fixtures? I have (will have after this evening anyway) two of them of them that I took down to replace with ceiling fans. Nearly brand new, installed a couple of months ago. Comes with all the mounting hardware and bulbs too. Bugs not included.

I also have a bunch of incandescent light bulbs that have been accumulating as they get replaced by fluorescent bulbs. More expensive than regular bulbs, but much more energy efficient and longer lasting. If anybody wants these incandescent bulbs, drop me a line. Free to a good home!

Maybe I need to have a garage sale...

Starting early this year

Storm season's getting off to an early start with Arlene spawning south of Cuba yesterday. Forecast track has it going north into the Gulf of Mexico, so not much of a bother for here (so far). Rainy weekend for people in AL/MS though.

Definitely need to start getting things prepared for the storm season.

A grilling fiend in the making!

With summer heating up and an empty back porch, the wife decided we needed to have a grill to do some outdoor cooking and entertaining with. So this weekend with the leftover house money we bought one of these. Assembled it Saturday, and had our first cookout yesterday. Nothing fancy, just a few burgers and some chicken. And boy, does it ever put out some heat. It was a little tough getting burners adjusted properly so I didn't burn the chicken to a crisp, but everything came out quite tasty.

I have a feeling I'll be getting plenty of practice getting things just right on this grill.

Multi-detector CT and PACS storage

For the past few months, I've been digging through our PACS database extracting all sorts of gory stats on the storage requirements for CT images. After the first of our 64 slice CT scanners was installed and hearing early reports about 1000 slice studies being stored, I started to get curious about the impact of multi-slice/multi-detector CT (MDCT) scans on our PACS archive.

Our PACS archive goes all the way back to 1996 when it was first installed, so there were a lot of numbers to go through.

Here are some graphs summarizing some of what I've found so far.

This is the number of studies per month being stored to the archive. Pretty boring, mostly linear growth happening here.

This is the total number of CT images being stored to the archive each month. You can see fairly steady growth early on with a hint of increase starting around 2000, when the first of our 2 and 4 slice CT scanners were getting installed. The big jump in images/study/month starting around 2003 marks the start of five 16 slice CT scanners being installed. You see another slight increase in the number of images/study/month happening around the end of 2004, which marks the installation of the first of two 64 slice scanners, replacing two of the 16 slice scanners.

Above is the average number of images per study per month being stored to the archive. You see similar trends going on here as with the total images. With MDCT, you have the ability to scan much larger volumes in the same amount of scan time, so naturally you can generate more images. And in order to generate nice looking coronal and sagittal reformats, you need to scan with thin slices which means even more slices.

This shows the maximum number of images being stored each month. As you can see from this graph, we are well past the point where thousand image studies were routine and are getting to where some of the largest studies are approaching 10 000 images. Of course the majority of these images are actually reformats and reconstructed images, not actual 'x-ray on' scans. The jump in max images around July 2003 coincides with the installation of 4 16 slice scanners.

Looking at just one CT room, we see what happens here when the switch is made from 16 to 64 slices. The initial data point is an artifact caused by the vast number of images I sent to the archive from acceptance testing the 16 slice scanner. The unit was replaced with a 64 slice scanner Sept 2004, where you see a slight increase in the average number of images stored each month. Then a few months later once the 'Wow' factor has kicked in and people start seeing just what the machine is capable of, zoom goes the average images per study.

A similar thing, although much more dramatic happens when we look at the total images stored each month for the same room. Following the switch to 64 slices, the total number of images doubles from what was being stored with the 16 slice scanner, partly because of an increased number of patients being scanned, and partly because of more images per study being acquired.

So what does all this mean? With each CT image taking up at least 512 kB a single CT study starts reaching the GB range for storage requirements. This makes the size of the on-line PACS archive in terms of the number of studies it can store becomes smaller. Studies get moved off-line onto tape or MOD sooner. The more MDCT scanners an institution has, the more pronounced this becomes.

Radiologists need new tools for viewing these massive data sets. 3D and volumetric visualization, which used to be considered just eye-candy for referring physicians, becomes essential for making it through the sheer volume of data.

Interesting stuff. I need to write this up and publish it some place.

New diagnostic x-ray system performance standards

Just learned today that the FDA issued the latest revisions to 21 CFR Part 1020, which outlines FDA standards for how diagnostic x-ray machines should perform.

Haven't had a chance to go through it yet, but glancing through the summary, I see a few notable changes:

• Switch to using KERMA and air KERMA for exposure measurements
• Changes to minimum HVL requirements
• Last image hold requirement
• Dose information display to the operator

It's a long 46 page document that will probably take a while to go through, but the summary provides references to the sections that changed so there's probably no need to wade through all of it. Some of the comments might be interesting though.

I hope their work is better than their spelling

This is from a flyer advertising lawn care services that was left on the mailboxes around here:

qualithy lawn serviece for a low priece. we do you lawn work in half the time it takes for the othe serveces and good quality serviece

More penguins!

Saw Madagascar over the weekend, and I gotta say, the penguins were my favourite. I wanted to see more of them. They should seriously get their own spin-off movie.

Definitely more of a kid's movie than Incredibles or the Shreks. The movie had it's moments and was definitely enjoyable. A little humour for the big kids as well. I thought it was worth seeing in the theater.

Thought the chimps were pretty funny too.

Teva tan!

The hallmark of any good Teva tan is the little triangle near the pinky toe where the straps join together. Some of the newer model Tevas seem to have done away with that triangular opening, or covered it up with some padding.

My Terradactyl's have served me well for the past several years, but it's time to get new ones soon. Actually I probably should have gotten new ones last year. The treads have worn down and I'm starting to slip and slide a little on wet surfaces. If I can find another pair in some store's leftover stock, I wouldn't mind another pair of Terradactyls, but I'm liking the look of the Terra Fi and the Stratum.

Tevas rock. They just do.

Journal Club: Performance of a static-anode/flat-panel x-ray fluoroscopy system in a diagnostic strength magnetic field: A truly hybrid x-ray/MR imaging system

In the world of hybrid and integrated imaging systems, you can't get much more incompatible than MR and X-ray, at least until now. I'd been hearing about work on such an x-ray/MR hybrid system for a few years now, and now there's a paper by Fahrig et al in this month's Medical Physics (R. Fahrig, Z. Wen, A. Ganguly, G. DeCrescenzo, J. A. Rowlands, G. M. Stevens, R. F. Saunders, and N. J. Pelc, "Performance of a static-anode/flat-panel x-ray fluoroscopy system in a diagnostic strength magnetic field: A truly hybrid x-ray/MR imaging system", Med Phys 32, 1775-1784 (2005)) describing the performance characteristics of a flat panel fluoroscopy and open MRI blended together.

Talk about bleeding edge imaging. Not something that would have been possible just a few short years ago before flat panel image receptors were available. With MR, you get great soft tissue contrast, but you can't see solid objects like bone, implants or wires. With fluoroscopy, you have decent resolution, good visibility of bone, implants, and wires/catheters, but soft tissue contrast isn't so great.

Not entirely sure what kind of clinical demand there is for something like this, but from the quick glance I gave at the paper, there have been a number of clinical procedures performed on it already. I look forward to digging into this paper and finding out more about the system.

Abstract:

Minimally invasive procedures are increasing in variety and frequency, facilitated by advances in imaging technology. Our hybrid imaging system (GE Apollo™ flat panel, custom Brand x-ray static anode x-ray tube, GE Lunar high-frequency power supply and 0.5 T Signa SP™) provides both x-ray and MR imaging capability to guide complex procedures without requiring motion of the patient between two distant gantries. The performance of the x-ray tube in this closely integrated system was evaluated by modeling and measuring both the response of the filament to an externally applied field and the behavior of the electron beam for field strengths and geometries of interest. The performance of the detector was assessed by measuring the slanted-edge modulation transfer function (MTF) and when placed at zero field and at 0.5 T. Measured resonant frequencies of filaments can be approximated using a modified vibrating beam model, and were at frequencies well below the 25 kHz frequency of our generator for our filament geometry. The amplitude of vibration was not sufficient to cause shorting of the filament during operation within the magnetic field. A simple model of electrons in uniform electric and magnetic fields can be used to estimate the deflection of the electron beam on the anode for the fields of interest between 0.2 and 0.5 T. The MTF measured at the detector and the DQE showed no significant difference inside and outside of the magnetic field. With the proper modifications, an x-ray system can be fully integrated with a MR system, with minimal loss of image quality. Any x-ray tube can be assessed for compatibility when placed at a particular location within the field using the models. We have also concluded that a-Si electronics are robust against magnetic fields. Detailed knowledge of the x-ray system installation is required to provide estimates of system operation. ©2005 American Association of Physicists in Medicine

Hybrid MR/X-ray fluoroscopy in Physics Today

Physics Today also had a much easier to read article describing the hybrid MR/X-ray system being developed at Stanford.

Since my PT happened to arrive in my mailbox before the MedPhys, I read about the new system there, and then discovered the paper in MedPhys. The MedPhys paper goes into a lot of gory detail about the system, so for those of you who don't have the stomach for it, the PT article is probably the more interesting one for you.

Thanks to Charles Day for the reminder about the article.

She's a swimmer!

The wife got to take Nala out to the off-leash area at James Island County Park today and had a good time. From what the wife tells me, Nala had a great time out there. The area is bordered by water, and after a few tentative splashes, Nala jumped right in to play with and chase some of the other dogs. She enjoyed being in the water so much it was tough to get her back out. Sounds like it was a good time.

Wish I could have gone too. Darned job...

The day is just crawling by

Need a new battery for my watch. I have 5 time keeping devices on my desk: my watch, 2 computers, PDA and binary clock. But it's the watch I always check most often. Go figure. So I start feeling munchy, go grab some left over lunch out of the fridge and head off to the microwave to heat it up. Glance at my watch and it tells me that it's only 9:20. I think to myself "Man, this day is just dragging. Hungry already and it's not even 9:30". So I go back to my desk, put lunch back in the fridge and do some more work.

Then a few minutes later I notice the time on the binary clock and PDA, which tell me it's actually 11:30! Well, heck, no wonder I'm so hungry. It really is lunch time!

So off to go heat up some lunch (again), and then figure out how to replace the battery in this watch.

Blogiversary #2!

So apparently I've had this blog going for 2 years and 677 entries (not including this one) as of today. I have to admit I'm a little bit surprised I'm still doing this, yet it doesn't really feel like it's been two years. Who'd have thought I'd have this much to say!

With all the new stuff going on (the house, new equipment at work, new research), I think this third year of blogging might be more interesting (at least for me anyway).

Stay tuned and see where the ride goes!

"Morgue" must not be PC anymore

I was walking down the hall past the Morgue, and noticed they have a new sign. I guess the Morgue people (or most likely some overly-PC administrator somewhere) have decided 'Morgue' is too crass, grisly or scary sounding so now they're calling it 'Decedent Affairs', which I guess is a more PC way of putting things.

My first thought on seeing the sign was "They spelled decadent wrong", but then I wondered what "Decadent Affairs" would be. Probably not entirely appropriate for a hospital. It probably would have been more interesting and a lot more fun though.

Paws everywhere!

Nala turns 6 months in a few days and is getting close to 55 pounds now. I'm sure her feet are growing faster than the rest of her, because she's got the biggest feet I've seen on a dog her size. In typical lab fashion, she's always following one of us around trying to see what we're up to, running to us or after us. So some part of us is always getting stepped on. A few months ago when she was smaller, it wasn't such a big deal, but now you definitely notice her big paws have intruded on your space.

That's some fertilizer they use

In less than a week, two floors of the corner of one building for the new hospital sprouted up with pillars to support the third floor going up as I left work today. At this rate this first building should be up within a year or so. From what I've heard, this building is supposed to house the diagnostic and treatment building: lab, radiology, offices, clinics etc. Should be fun watching the tower building go up. The campus is going to be a busy place for a long time.

Just another count

TS Bret and 5 months to go

Tropical Storm Bret popped up off the coast of Mexico overnight to bring heavy rains to the southern part of the area. Already on the way inland, it should be pretty short lived. That's two storms already this month, and still 5 months left in the season to go. At this rate it's shaping up to be quite the season.

LNT prevails

Supporters of the linear-no threshold model of radiation risk got a big boost from the National Academy of Science in a report (BEIR VII Phase 2) released yesterday.

Personally, I'm not a fan of LNT. It's an overly conservative model and considering that every living organism on the planet evolved in a sea of terrestrial and cosmic background radiation, it just doesn't make much intuitive sense. The problem is that at low doses, the statistics just aren't there, and what is there is incredibly noisy. So trying to extract anything meaningful in terms of risk/adverse effect is stretching things pretty thin.

However, considering that regulatory agencies already develop recommendations and regulations based on LNT, I don't expect there to be much of an impact on the way us radiation people work.

From the NAS:

Low Levels of Ionizing Radiation May Cause Harm
June 29 -- A preponderance of scientific evidence shows that even low doses of ionizing radiation, such as gamma rays and X-rays, are likely to pose some risk of adverse health effects, says a new report from the National Research Council. In living organisms, such radiation can cause DNA damage that could eventually lead to cancers. The report provides a comprehensive assessment of these risks based on a review of the scientific literature from the past 15 years. It is the seventh in a series of assessments from the Research Council called the Biological Effects of Ionizing Radiation.

From the Report-in-Brief:

the current scientific evidence is consistent with the hypothesis that, at the low doses of interest in this report, there is a linear dose-response relationship between exposure to ionizing radiation and the development of solid cancers in humans. It is unlikely that there is a threshold below which cancers are not induced, but at low doses the number of radiation-induced cancers will be small. Other health effects (such as heart disease and stroke) occur at higher radiation doses, but additional data must be gathered before an assessment of any possible dose response can be made between low doses of radiation and non-cancer health effects. The report also concludes that with low dose or chronic exposures to low-LET irradiation, the risk of adverse heritable health effects to children conceived after their parents have been exposed is very small compared to baseline frequencies of genetic diseases in the population.