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.

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

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.

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.
Studies per month
This is the number of studies per month being stored to the archive. Pretty boring, mostly linear growth happening here.
Total images per month
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.
Average images per study per month
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.
Maximum images per study per month
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.
Total images per month for HVC
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.
Average images per study per month
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.

Continue reading “Multi-detector CT and PACS storage”

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.