Vintage mammography phantom

Just about every medical physicist has a collection of old test gear, phantoms, test objects ,meters and the like.

A few years ago, while rummaging through the equipment cabinet in our store room/library/lab, I came across a variant of a mammography phantom that I hadn’t seen before. Instead of the normal pink wax insert, this one had 16 wax squares of different colours.

Old RMI mammography phantom SN 152-1015
Old RMI mammography phantom SN 152-1015

Aside from the curved bit of plastic at one end of the phantom (a test object, not a ghostly apparition), it’s the same size as the conventional ACR accreditation phantom. Reminds me of one of those sliding number/picture puzzles where you have to slide the squares around to reconstruct the image.

Old RMI mammography phantom SN 152-1015
Old RMI mammography phantom SN 152-1015 side view

I let it sit on my book shelf along with some of the other pieces in the collection. A few months ago, I decided it was time to have a look and see what the inside of the wax blocks looked like.

Old RMI mammography phantom SN 152-1015
Old RMI mammography phantom SN 152-1015

Looks like at some point in its history, the pieces got a little scrambled and reinserted a bit randomly. I was expecting that each colour block would represent a different density. Instead there are the usual fiber, speck, and mass groups, but not nearly as uniformly placed as in the accreditation phantom.

I don’t know how old this phantom is or what time frame it might have been used at work. The only mammography phantom I was familiar with before this one was the pink one, so possibly before 1996 at least. Definitely pre-1999.

If anybody out there happens to know anything about this style of mammography phantom, let me know.

Getting Lucky

Sometimes you come across some interesting novelty books. Some selected excerpts from Luck: The Essential Guide.

An empty hornet’s nest, hung high, is a good-luck charm for the whole family.

An occupied one, probably not so much.

The cardinal rule for the New Year’s meal in Sicily is this: good luck comes only to those who eat lasagna. Those who eat fettuccine, macaroni, fusilli, tagliatelle, or any other pasta do so at their own risk

This is a tradition I could get used to.

When in Rome: Stay away from nuns. If a nun can’t be avoided, touch iron (knocking on wood Italian-style) immediately after seeing one to preserve good fortune. You can also do as the Italians do and mutter “Your nun!” to the next person you see, passing the nun (and therefore the bad luck) to someone else.

When in Japan: Pay attention to the first person you meet each morning. If it’s a woman, you’ll have good luck, but if it’s a Buddhist priest, you’re in for a bad day.

I wonder what it is with religious figures…

Try selling  your health problem to a friend. Offer to give her a good deal – say, a buck fifty – on your tendonitis. Some believe that the evil spirits that control the illness will get confused as to who should actually have it and the problem will go away.

Those spirits are pretty gullible. T2 diabetes anyone? I can give you a great deal.

Time to retire the HP 28S

Looks like it’s time to retire my trusty old HP 28S calculator that I’ve had since my second year of undergrad.

Popped a fresh set of batteries into the calculator (after it had been sitting idle and battery-less for a while). Calculator powered up just fine, but the Enter row and G-L row of keys weren’t working. Twisting the body of the calculator a bit will make the Enter key work, but not reliably. Also makes using the calculator kind of awkward.

While searching the webs for documentation on how to disassemble an HP 28S, I came across this Museum of HP Calculators forum post about disassembling one that was having problems with keys not working.

Definitely not a trivial process.

I found that by pushing down on the keypad near the back arrow button, all of the keys that weren’t working would work again.

It seems like the whole calculator is held together by an array of posts that are “welded” to the upper and lower halves of the case. When some of those posts break, the connection between the keyboard and the rest of the calculator gets flaky because there’s less pressure holding everything together.

From one of the posts on the forum thread:

heat stakes that had sheared off, primarily from the case back, not the mushroomed heads. I suspect it is the physical force from opening the case that stresses the heat stakes in the latch area that causes them to fail. Once that happens, there is a zipper effect to the left that eventually leads to failure of the smaller diameter stakes under the display that causes the classic loss of keyboard to logic board contact.

The forum thread also mentions replacing foam that helps press the keyboard contacts against the calculator’s logic board. After almost 30 years, I’m sure that’s also part of the problem with this calculator too.

Probably not worth the effort to try and fix this calculator. I’ll keep it around as a museum piece and for sentimental reasons.

Fortunately the other one I bought a few years ago still works.

Happy birthday Theresa

You would have turned 41 yesterday.


How remarkable would that have been?

The hops plants have been growing really well on your hops tower. You would like the tower. It’s got a good spot in the Medicinal Garden. Normally winter makes the hops plants die back and they get cut back to the ground. This past winter being on the warm side, the plants just kept growing. There were quite a few hops flowers this year too.

Connie and I requested a Mass to be offered for you back in May, like we usually do. Even though I’m not Catholic, and even though you’re usually not very far from my thoughts, I find it offers a nice opportunity to bring back some memories.

I inherited a laptop from your mom because she wasn’t really using it anymore. It was a bit of an unexpected surprise, and I thought it was nice of her to let me have it. I put it to work as a development machine for when I want to work on some of my projects, but don’t want to be stuck in my office. It reminds me of your laptop, Pinky, but I think yours was a different colour as I recall.

Your parents also gave us a couple of rose bushes at our housewarming party last year. I don’t have much skill at growing things, but they managed to survive the winter and have been producing quite a few roses over the summer.

The bushes have some pretty fierce thorns, but the roses smell really nice.

I was happy your parents were able to join us for the housewarming. It seems like they’re enjoying their retirement down in Florida these days.

All of your family and friends miss you.

I miss you my friend.