Computer upgrades

The computer got another hard drive upgrade when the 1TB drive holding my home directory started throwing errors and disappearing from the system. After causing a small amount of panic and a few reboots, the drive managed to stay stable enough for me to get it backed up to the LVM partition. Now it’s been replaced with a 1TB SSD which has given me a nice speed boost.

The nearly 10 year old mid-range (at the time) video card, a GTX 260, also got an upgrade to a much newer and higher end GTX 1660 Ti. The GTX 260 was getting pretty old, and I was starting to get some weird errors with the nouveau driver, so I figured it was time for an upgrade. The new card is about 2/3 the length of the GTX 260, which gives a little more room around the SATA ports and hard drives to work. Hopefully I’ll be able to put the GPU to some number crunching work at some point, and later maybe get into a bit of gaming (after the PhD of course).

KitKats: Canada vs USA

One of the things we brought back from our trip to Edmonton a few weeks ago was a variety box of Halloween candy: Aero, Coffee Crisp, Smarties, and KitKats.

Naturally, we got some US KitKats to compare with the Canadian KitKats. These are the mini Halloween sized candy bars, not the full size bars.

In Canada, KitKats are a Nestle product while in the US, they’re a Hershey product manufactured under license from Nestle. Size differences aside, they’re also a little bit different on the inside.

KitKat cross-section. Left: Canadian KitKat. Right: US KitKat

First thing that’s noticeable is that the layer (chocolate?) between the wafers is darker and more distinct in the Canadian KitKat. It’s hard to tell there’s anything between the wafer layers of the US KitKat, but it turns out the inter-wafer stuff just a different colour.

Between the wafers. Left: Canadian KitKat. Right: US KitKat.

Taste-wise, the Candian KitKat seems a little crisper, and a bit more chocolatey than the US KitKat. If I was doing a taste test, I’d choose the Canadian KitKat.

Mah gimpy foot followup

First, everybody thought maybe the lump on the side of my big toe left over from the sprain might be gout, or pseudo-gout. After a course of medication without any change, my doctor referred me to rheumatology. The rheumatology PA I saw was dubious about it being gout-related, especially since there wasn’t the usual pain associated with gout. Possibly some residual slow-healing damage from the sprain.

After a second follow-up appointment with the PA, I got some additional x-rays of the toe to check for anything like a stress fracture that might not have been seen with the foot x-rays.

Nothing obvious to my eyes, and they look pretty similar to the foot x-rays done back in July. Lump on the side of my right toe appears to be just soft-tissue related.

Looks like I just keep an eye on it now and see if it eventually heals up.

PhD Candidate!

After doing my qualifier presentation back in May, I discovered there was another step before I could become a PhD Candidate.

The proposal presentation is supposed to demonstrate to the committee that my research is going on the right track and I’m actually capable of doing the work. Mine took the form of an NIH format grant proposal and a presentation to my committee.

Today I gave my presentation, and my committee saw fit to pass me, so now I can call myself a PhD Candidate!

This is good…I think.

Now the rest of the work begins.

A new portable x-ray unit

A new Carestream DRX Revolution Nano portable x-ray unit arrived at work this week. Normally the arrival of a new portable x-ray unit wouldn’t be a terribly notable event, but the size of the unit and label on the tube head intrigued me.

It’s a pretty compact unit (about the size of a shopping cart), weighing in at just over 100 kg. The x-ray tube is considerably smaller than a normal x-ray tube. I was told by the service engineer that the x-ray tube uses carbon nanotubes for the cathode. I had read about this technology a few years ago, but wasn’t aware that it was being used commercially. This is the first application I’ve heard of in the medical imaging world.

The machine is quiet during the exposures, without the normal sound of an x-ray tube anode spinning up, so I suspect this is a tube with a stationary anode.

The Nano turns out to be a pretty low power unit, even for a portable unit. The x-ray technique maxes out at 110 kV and 12.5 mAs. At 60 and 80 kV, the maximum mAs was 20 and 16 respectively. Not entirely sure if this was just a soft limit based on the imaging protocol I selected, or a hard limit. I still need to go through the documentation and the technical specifications for the unit.

Radiation output in mGy/mAs was pretty similar to a conventional x-ray tube (compared to a Shimadzu portable unit in the graph below).

Radiation output (mGy/mAs) graph
Radiation output for the Carestream Nano (orange diamond) and Shimadzu portable ( blue square)

Exposure times for the Nano were quite a bit longer though, so the tube obviously operates at a considerably lower tube current than a conventional x-ray tube. Pretty clear from the exposure rate graph below that while the mGy/mAs is similar, the Nano tube is spitting out much less radiation.

Exposure rate (mGy/s) graph
Exposure rate (mGy/s) for the Carestream Nano (orange diamond) and the Shimadzu portable (blue square). Multiple values at 80 kV are exposures at different mAs settings.

Crunching a few numbers, I found that the tube current for the Nano goes between 30 – 60 mA, about 1/4 of what I might expect for a regular portable x-ray unit, but about what I’d expect for something with a stationary anode.

kV/mA graph
mA range at different kV settings for the Nano (orange diamond) and Shimadzu portable (blue square)

As far as the kV and exposure rate wave form goes, it’s about as perfect as I’ve ever seen from any x-ray tube. Excuse the small size of the graph. The software for my meter started spitting out tiny images into my spreadsheets instead of the big ones it used to, and I haven’t figured out how to fix it yet.

kV and exposure rate wave forms for the Nano
Exposure rate (green) and kV (red) wave forms from the Nano

It’s a pretty neat little unit. Should be pretty decent for imaging babies and small kids (unless they’re very squirmy), but probably a bit under powered for imaging anything larger than a toddler. I predict the addition of another more conventional portable x-ray unit a few months down the road.