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.

Toilet shopping

Finally got around to replacing the wax ring on the toilet this week. Simple enough job.

Unfortunately once I got everything back together and tested, the toilet was still leaking. The wax ring seemed to be sealing everything up just fine. Finally with a little more investigating I discovered the culprit: a tiny 5 mm long crack at the base just outside the wax ring.

I wasn't able to get a very close look at it without dumping the remaining water out of the bowl, but it looked like it may have been a manufacturing defect.

So I guess it's off to Lowe's sometime this week to shop around for another toilet. We'd been meaning to upgrade the toilets anyway...just not quite so soon.

Delightfully cool

While most people here are starting to bundle up and feeling a little chilly, I'm loving the weather out. It's like September weather back home. Cool crisp mornings, and cool enough in the day that you can bask in the sun and not get too hot.

My internal thermostat's starting to switch over, so I have to step outside every now and then to cool off. Even 18°C (that's 65°F for you non-metric folks) gets a little toasty for me now. Walking around wearing just a shirt and jeans when everyone else has coats on does get me a few odd looks though.

Numb3rs

Anybody watch Numb3rs? Finally managed to catch an episode of it last night while waiting for Battlestar Galactica to come on and rather enjoyed it. It's nice to see Rob Morrow and Peter McNichol back on TV again. Yesterday's episode was about trying to figure out a pattern to blackouts some guy was causing so that some bad guy drug dealers could get into a prison and eliminate someone that was going to testify against them. Some of the math technobabble stretched things a little, but overall it seemed pretty realistic. The slide rule Peter McNichol's character was playing around with in a few scenes was a nice touch.

Now that I know when it's on, I'll probably try to tune in a little more regularly.

More fun with dogs

Yesterday we were at the Coastal SC Lab Retriver Club's Lab Fun Day. A little bit on the breezy side, but a nice sunny day. Simba's breeder greeted us with a loud and friendly "Look at the Canadian!!" (I was the only one in just a shirt...everyone else was wearing a sweater or jacket).

Plenty of fun was had for both dogs and their people.
There were obedience demonstrations and an obedience course for people to try out

There were retriever demonstrations by some dogs that really knew what they were doing. They did retrieves on land

and in the water

There were also fun contests for dogs and people to participate in. Tail wagging


and a dog dress-up contest


This guy skipped all the contests and went right for the cookies


Seemed like everybody who stopped by had a good time. Even the non-labs came to check things out and have fun.

A new toilet at last

Well, fixing that leak in the toilet ended up being a considerably more arduous task than expected.

• Disassembled the old toilet to replace the wax ring. Still leaked
• Tried another wax ring just in case I didn't get a good seal the first time. Still leaked.
• Discovered a small crack at the base of the toilet. Ick.
• Go to Lowe's to buy a new toilet and tank.
• Get home, install the toilet bowl. Wife decides the round bowl is too small and just won't do. Much cursing in my brain. Remove everything, stick it back in the box and take it to Lowe's for a refund.
• Take off to the N Charleston Lowe's to buy the elongated bowl version (the only store that has it in stock). Get there 10 minutes before they close and buy the last one they have. Also buy yet another wax ring and new toilet seat.
• Get home, discover that I mistakenly stuck some parts belonging to the tank into the toilet bowl box that we returned 45 minutes ago. Crap.
• Go back to Lowe's in the morning and retrieve the parts.
• Install the bowl. Fill with water to test flushing. No leaks (whew!).
• Install the tank. Connect up water hose and turn the water on. Tank fills, no leaks (happy happy joy joy!).
• Flush when the tank fills. Flushes great, no leaking (happy dance!). Flush a couple more times just to make sure.
• Inform wife. Wife christens toilet. No leaking, although she says it's taller than expected.

So now we have a new uber-flushing toilet that works way better than the original toilet. Now the wife wants to replace the other toilet.

Sleepy dog

I think I'll just have a nap here while you work...

My Geek Code

Yes, I'm a geek and proud of it, and this is my Geek Code.

To find out the meaning of a particular code, click on it and you will be taken to the appropriate entry in the Geek Code. Want to build your own Geek code? Go to the Official Geek Code page. Here's a nifty Geek code decoder. Decode mine.

-----BEGIN GEEK CODE BLOCK-----
Version: 3.12
GS d-(+) s: a C++ UX++++V++S++++L++++ P+>+++ 
L++>+++ E+>++ W++(+++) N++(+++) o? K? w !O !M 
V-- PS PE+ Y+ PGP++ t++ 5++ X++ R+ tv++ 
b++(+++) DI++++ D+ G++ e+++>++++ h--- 
r+++ y+++ 
-----END GEEK CODE BLOCK-----

The Imabug FAQ

Why do I call myself Imabug?

This cartoon is copyrighted and is here purely for your viewing pleasure Do not redistribute because we'll both get into trouble. Thanks.

The cartoon is from Something Under the Bed is Drooling btw. You should go out and get a copy. :)

Evaluation of a Triple Energy Window Scatter Correction Method for SPECT Imaging

Back when I was doing my medical physics residency (oh about 6 or so years ago now), I was asked to evaluate a triple-energy window technique for scatter reduction in nuclear medicine imaging. I stashed a copy of what I wrote up over on my other much neglected website and just thought I'd move it over here for storage and posterity. It's pretty rough and not anywhere near any kind of publishable state, but it was fun to work on and provided a good learning experience.

Objective

To test and evaluate the usefulness of the Triple Energy Window (TEW) method for scatter correction proposed by Ogawa et al.

Background

In a scatter correction method proposed by Ogawa et al¹, the number of scattered photons in each pixel is estimated using two energy windows adjacent to the main photopeak window. The number of scattered photons in the photopeak window is determined by calculating the area of the trapezoid underneath the line joining the two scatter windows in the scatter spectrum.

For each pixel in the photopeak projections, the number of scatter counts is determined using the ollowing equation

C_scat ~ (C_lower/W_s + C_upper/W_s)*W_m/2

where

C_lower = counts in left window
C_upper = counts in right window
W_s = width of left and right scatter windows (keV)
W_m = width of photopeak window (keV)
C_scat = number of scatter counts

Phantom studies and computer simulations performed by Ogawa et al and Ichihara et al² showed the method could estimate the number of scattered photons fairly accurately. However, neither paper addresses the potential for increased noise when the scatter counts are subtracted.

A Monte Carlo investigation of the method by Ljungberg et al³ questioned the use of the upper (right) scatter window noting that using the right scatter window might make the TEW method more susceptible to noise. When only the lower energy window is used, C_lower = 0 and the estimated number of scatter counts becomes

C_max = (C_lower*W_m)/(2*W_s)

Monte Carlo simulations performed by Buvat et al⁴ demonstrated an 18% overestimate of the scatter counts when both scatter windows were used, and a 14% underestimate of the scatter counts when only the lower scatter window was used. Good relative activity quantification was also demonstrated by the simulations when only the lower window was used.

Equipment

• Jaszczak phantom with cold rods and spheres
• ACNP kidney phantom
• Picker PRISM 3000 triple head SPECT camera

Method

A standard Jaszczak phantom containing the solid rod and spheres inserts was filled with water and 1110 MBq (30 mCi) of Tc-99m. A SPECT acquisition was acquired using three energy windows

1. Photopeak - 15% window centered at 140 keV.
2. Scatter1 - 3 keV window centered at 126 keV.
3. Scatter2 - 3 keV window centered at 153 keV.

with these acquisition parameters: 120 projections, 30 s/projections, 3 degrees/projections and a 128x128 projection matrix. The images from each energy window was stored in a separate file.

The ACNP (American College of Nuclear Physicians) kidney phantom consists of two fillable kidney objects with a cold spot defect located in the middle of the right kidney and superior portion of the left kidney. The objects were filled with approximately 370 MBq (10 mCi) of Tc-99m and placed within a water bath. A SPECT acquisition was acquired using the same energy windows used for the Jaszczak phantom, 120 projections, 30 s/projection, 3 degrees/projection and a 128x128 projection matrix.

Processing

Once the acquisition is complete, there are three files, the photopeak projections, and two scatter projections. The TEW method was performed two different ways; with both scatter windows (TEW2) and with just the lower scatter window (TEW1) as suggested by Ljungberg et al. All image processing was done through the Odyssey software.

TEW2

1. Divide the counts in each pixel of the scatter projections by the width in keV of the scatter window.
2. Add the two scatter window projections together.
3. Multiply the resultant projections by half of the photopeak window width in keV.
4. Subtract the result from the original projections.

TEW1

1. Divide the counts in each pixel of the scatter projections from the lower window by the width in keV of the scatter window.
2. Multiply the resultant projections by half the photopeak window width in keV.
3. Subtract the result from the original projections.

With the window settings used in this experiment (3 keV scatter windows, 15% (21 keV) photopeak window), the scatter correction using both lower and upper scatter windows was performed by adding the scatter projections together and multiplying the result by a factor of 3.5. The scatter projections were then subtracted from the main photopeak projections. For the TEW1 method, the pixels of the lower scatter window projections were scaled by a factor of 3.5 and subtracted from the photopeak window projections

Reconstruction

A 3 pixel thick slice was reconstructed with a ramp filter through the center of the spheres from each of the corrected and uncorrected projections. To investigate uniformity and noise, a 9 pixel thick slice was reconstructed with a ramp filter through the uniform water section of the phantom. Attenuation correction was applied using the system attenuation correction software and an attenuation coefficient of 0.11 cm^-1. No additional postfilters were applied to the reconstructed images.

The ACNP kidney phantom was reconstructed using a ramp filter and single pixel thick slices, and then filtered using a Wiener 3-D postfilter. The filtered images were reformatted to 3 pixel thick coronal and transverse slices. No attenuation correction was applied to the phantom images.

Results and Discussion

The total counts per projection in the ACNP kidney phantom images ranged from 15-20 kcounts in the photopeak window, 1.5-2.6 kcounts in the lower scatter window and 300-600 counts in the upper scatter window. The count loss when both scatter windows were used to estimate the scatter counts in the photopeak window was almost 50% (6-10 kcounts/projection subtracted from the photopeak projections) and around 35% (5-9 kcounts/projection subtracted) when only the lower scatter window was used.

Circular ROIs was drawn through the each sphere of the Jaszczak phantom to obtain the mean counts/pixel within the sphere for the corrected and uncorrected images. The same ROIs were used to obtain the mean counts/pixel from the center of the phantom. The percent contrast for each sphere was calculated using the equation

% Contrast = (bkg counts - ROI counts)/bkg counts

The most noticeable problem with the scatter corrected images is a significant decrease in counts and increase in noise. The inherent noisiness of the ramp filter also contributes to the noise in the reconstructed images. An interesting item to note is the improved contrast when only the single window is used compared to when both windows are used. This suggests that using only the lower scatter window may produce better results as suggested by Ljungberg et al³. Neglecting the higher scatter window for the higher energy photopeak is also recommended by Ogawa to avoid increasing statistical noise.

The additional noise introduced by the TEW scatter correction may be compensated for somewhat by applying a different filter to the projections or postfiltering the reconstructed images.

The slices from the uniform section of the phantom was used to determine the uniformity and noise of the corrected and uncorrected slices. The mean, standard deviation, maximum and minimum counts per pixel from a 15x15 pixel ROI were used to calculate the integral uniformity and the RMS noise level for the uniform section. The relatively high uniformity values are a result of the ramp filter which is inherently noisy.

When both the upper and lower energy windows are used the integral uniformity increases significantly. This a result of the subtraction of the scatter counts from the projections.

Using a just the lower energy window to estimate the scatter improves the integral uniformity slightly, although the values remain relatively high compared to the uncorrected images.

The noise level in the reconstructed images can be largely alleviated by filtering the images as is commonly done with clinical studies. However, the uniformity of the scatter corrected filtered images will still be greater than the uncorrected images simply because of the loss of counts incurred when the estimated scatter counts are subtracted.

A Wiener 3-D postfilter was applied to the same images resulting in a significant improvement in image noise. However, the scatter corrected filtered images still demonstrated greater non-uniformity and appeared noisier than the uncorrected filtered images.

Evaluation of the ACNP kidney phantom was performed qualitatively on both the filtered and unfiltered images. In all images, both defects were clearly visualized, although the scatter corrected images showed a lower count density and noise was increased significantly. Applying a Wiener 3-D postfilter improved the appearance of the images considerably.

Conclusion

The triple energy window scatter correction method evaluated using the Jaszczak and ACNP kidney phantoms showed decreased count images and increased noise, although contrast was improved. The phantom studies suggest that the triple energy window method may not be well suited for studies involving large distributions of radioactivity such as brain or liver studies because of the poor noise and uniformity properties. This scatter correction method may prove to be more applicable to studies involving smaller discrete radioactivity distributions such as cardiac or renal studies. Planar studies may also benefit from this correction method, although it was not investigated here. The ramp filter used to reconstruct the corrected and uncorrected images is inherently noisy, so the use of more optimal filters in addition to or instead of the ramp filter when reconstructing images should be considered. Further research using more clinically relevant phantoms is needed to further evaluate the noise and uniformity properties of the TEW method.

Bibliography

1. Ogawa K, Harata Y, Ichihara T, Kubo A, Hashimoto S, A practical method for position dependent Compton scatter correction in single photon emission CT, IEEE Trans Nucl Med, 10:408-412 1991
2. Ichihara T, Ogawa K, Motomura N, Kubo A, Hashimoto S, Compton scatter compensation using the triple-energy window method for single and dual isotope SPECT, J Nucl Med 34:2216-2221 1993
3. Ljungberg M, King MA, Hademenos GJ, Strand SE, Comparison of four scatter correction methods using Monte Carlo simulated source distributions, J Nucl Med 35:143-151 1994
4. Buvat I, Rodrigues-Villafuerte M, Todd-Pokropek A, Benali H, Di Paola R, Comparative assessment of nine scatter correction methods based on spectra analysis using Monte Carlo simulations, J Nucl Med 36:1476-1488 1995

10-17

Went out to this new sports bar called 10-17 tonight with a couple of friends. Small crowd tonight (not much sports going on I guess). Nice place, although I think it suffers a bit from poor location. It's tucked away in the Quadrangle Shopping Center next to the Piggly Wiggly on Skylark Drive (across from Citadel Mall).

Big comfy sofas in the front of the room, large spacious tables to gather around in the rest of the place. There are about 4 or 5 big flat screen TVs lining the walls to watch and dartboards and a shuffleboard to play on too. Plenty of board games to play while you're sipping a few brews or chowing down on some food. The menu is a mixture of standard bar grub and a few German dishes. Since Max & Moritz over in Mt P closed down earlier this year, 10-17's become about the only place I can think of where you can get decent German food. The two people from Germany that I was there with tonight didn't seem to object to the food, so I guess it must have been pretty decent by their standards. Prices are pretty reasonable too with most things in the $6-10 range.

Best of all, the whole place is smoke-free, so you can go there and spend a few hours hanging out without smelling like an ash tray when you leave.

Overall, it's kind of like the Map Room but with sports instead of music. A nice comfy place to go hang out with friends after work.

The Interviewer

Tomorrow I have the task of interviewing a well known and prominent physicist in my field for a position here.

This is a strange position for me. I've never interviewed anybody before, and usually it would be me in the interviewee spot and him in the interviewer position. Admittedly, I'm a little nervous about what kinds of things to ask him and talk to him about. I have a few things, but I'll need to come up with a more to fill up the 30 minute time slot I have with him.

This should be interesting.

111 years of x-rays

111 years ago today, a physicist by the name of Wilhelm Röntgen caught a glimmer of light coming from a fluorescent screen located across the room from his cathode ray tube setup. The strange phenomenon caught his interest and he spent several weeks investigating the matter.

Röntgen had just "discovered" x-rays. A month later he created the first radiograph (röntgenograms as they were called back then), an x-ray image of his wife's hand. The new rays were a huge hit among physicists, enabling the discovery of all kinds of wonderful things about the properties of matter. Once word reached the medical community of this new discovery, it wasn't long before Röntgen's new rays were used to image and treat patients.
The first x-rays were used to treat a breast cancer patient a mere two months after Röntgen's discovery. Shortly after came Edison's fluoroscope machines for visualizing x-rays in real-time. From there, the rest was history.

References:
Juan A del Regato, Radiological Physicists, American Association of Physicists in Medicine, 1985
Seliger HH, "Wilhelm Conrad Röntgen and the Glimmer of Light", Physics Today, 1995(11), 25-31

Mercury Transit

Later on this afternoon with a properly configured telescope configuration, you'll be able to catch Mercury's transit across the sun. If you don't have access to a properly configured telescope, you can catch the action live from SOHO's point of view. The transit is supposed to start at 1912UTC, or 1412EST (2:12 PM). Mercury's only going to do this 14 times this century, and this is the second one so far.

Journal Club: The 2006 Henry N Wagner Lecture

Today's journal club article isn't really an actual research paper, but more of a 'where are we now and where are we going' type of article written by a prominent nuclear medicine physicist, Simon Cherry. It comes from the November issue of The Journal of Nuclear Medicine. The article is The 2006 Henry N. Wagner Lecture: Of Mice and Men (and Positrons)—Advances in PET Imaging Technology (J Nucl Med 2006 47: 1735-1745)

By far the most interesting part of Cherry's article is where he looks forward to the future of PET imaging and raises the idea of PET/MRI imaging and whole-body PET/MRI imaging.. Rather than using conventional photomultiplier tubes, which would be rendered useless by the magnetic field from the MRI unit, the scintillation light would be detected by avalanche photodiodes. Very tantalizing possibilities indeed.

Abstract:

There have been major advances in PET technology that cumulatively have helped improve image quality, increased the range of applications for PET, and contributed to the more widespread use of PET. Examples of these technologic advances include whole-body imaging, 3-dimensional imaging, new scintillator materials, iterative reconstruction algorithms, combined PET/CT, and preclinical PET. New advances on the immediate horizon include the reintroduction of time-of-flight PET, which takes advantage of the favorable timing properties of newer scintillators; the integration of PET and MRI scanners into a dual-modality imaging system; and the possibility of further significant improvements in spatial resolution in preclinical PET systems. Sensitivity remains a limiting factor in many PET studies. Although, conceptually, huge gains in sensitivity are still possible, realizing these gains is thwarted largely by economic rather than scientific concerns. Predicting the future is fraught with difficulty; nonetheless, it is apparent that ample opportunities remain for new development and innovation in PET technology that will be driven by the demands of molecular medicine, notably sensitive and specific molecular diagnostic tools and the ability to quantitatively monitor therapeutic entities that include small molecules, peptides, antibodies, nanoparticles, DNA/RNA, and cells.

Mars claims another one

Looks like Mars may have may have claimed yet another probe. After 9 years in operation in Mars orbit, the Mars Global Surveyor has gone silent.

From the NewScientest blurb:

An unexpected break in communications has NASA struggling to restore contact with its Mars Global Surveyor (MGS) spacecraft. If communication cannot be restored soon, NASA may try to diagnose the problem by having another spacecraft, the Mars Reconnaissance Orbiter, take pictures of MGS.

If no signal is heard on either day, NASA may call on the Mars Reconnaissance Orbiter (MRO) to take pictures of MGS early next week. The two spacecraft pass within about 100 kilometres of each other several times each week.

MRO's camera is easily powerful enough to determine the orientation of the spacecraft and its solar arrays. This would reveal whether the spacecraft has gone into safe mode or not.

Considering MGS is in it's 4th mission extension, it's lasted remarkably well. Hope the NASA eggheads can manage to figure out the problem and recover the orbiter.

Blues Brothers quote

Elwood: It's 106 miles to Chicago, we've got a full tank of gas, half a pack of cigarettes, it's dark and we're wearing sunglasses.
Jake: Hit it.

From The Blues Brothers

Remembrance Day

For Canadians, Remembrance day is generally a very solemn day. It's a day to remember the Canadian soldiers that fell in battle in the first and second World Wars and other past conflicts, and the ones currently in battle. Canadians have played small but significant roles in past conflicts, and continue to do so today.

Take a moment out of your day to remember and think about what those soldiers have done and are doing now.

Walking on water

Cornstarch and water to be precise. In the proper mix, it becomes a non-newtonian fluid that behaves like a solid when placed under stress, and a liquid otherwise. I've seen demonstrations of the stuff on a much smaller scale, but never anything this size. Looks like fun!

Watch it at YouTube or GoogleVideo.

Found at Physics Blog.

Time for more writing

Just finished submitting one paper to JNMT. A couple of days ago I found out that an abstract I submitted to the SIIM annual meeting was accepted, so now I have to write up a paper to submit to JDI and a 12 minute talk for the meeting.

Since the meeting's not until June, I have some time for the talk. Need to get working on the paper pretty quick though.

Sounds of the holidays

I noticed yesterday that at least one local radio station has started up their endless loop of holiday tunes. At least this year they had the decency to start it up a little later than they did last year.

Let the holiday saturation begin!

I want my two hours back!

I didn't want to go see it. The wife knew I didn't want to go see it. She dragged me out to the theater anyway to double-date it with a friend of ours. Borat. Ugh, what a complete waste of time it was. I've never found that ambush-style of humour very funny anyway. While Borat does highlight some of the cultural ignorance and attitudes of stereotypical Americans (whether on purpose or not), I thought the movie was just one long painful experience.

-5 stars out of 5.

I should have let the rest of them see it and gone to see Flushed Away instead.

Who do I see about getting my two hours back?

They...broke...it...

Didn't get to see the Grey Cup this year but from what I've been reading it was a pretty good game between BC and Montreal with BC taking all the glory in a 25-14 victory.

And then they broke it.

How horrifying that must have been for the Keepers of the Cup? Could you imagine handing over the cup to the victorious players and then seeing the nearly 100 year old trophy head off in two directions?

Fortunately it's back in one piece and hopefully a little stronger than before.

It's snowing!

Imagine my shock and surprise when the wife told me it was snowing outside. It's actually coming down pretty good out there too (for around here anyway). There's a low pressure system just off the coast sucking cold air in, which is apparently cold enough at higher elevations to turn the rain into snow!

Cool. Too bad it's not cold enough for it to stick around.

Check it out

Tryptophan coma time

Tis the season for travel, family gatherings and tryptophan-induced comas. Later on this afternoon we'll be bundling up the dogs and our kitchen, packing up the car and heading off to the in-laws for our usual Thanksgiving catering gig. The wife's parent's really don't do whole lot of cooking and don't have the best equipped kitchen (by our standards anyway, although it is nice and big) so we usually end up packing along a good chunk of our kitchen for these things.

Not sure how many people to expect this year, but I don't think it will be too many. We only ordered a 20 pound turkey this time. Maybe this year I'll remember to photo-document the turkey cooking process. This year we're working on our gravy making technique.

Turkey pickling

Arrived at the in-laws safe and sound, although a little later than expected. Turkey's in the cooler brining, and I forgot to take pictures again.

Rats.

Well, it's a good looking bird anyway. I'll try to remember to take pictures of it tomorrow when we start roasting it.

Happy thanksgiving!

Happy thanksgiving!

Turkey's roasting away in the oven, cranberry sauce is done and we're working on the mac and cheese. In a few hours, the house will be stuffed with people and about an hour after that, stuffed people.

Hope everyone else has a good one!

Puppy sitting

Yesterday the wife and I got to puppy-sit for Gabby's latest litter (she also happens to be Simba's mom) while her people parents were out celebrating their anniversary. Gabby was a little defensive about her puppies at first but she eventually warmed up to us being in the room with her. She even let us pick up and hold some of her babies too.

The puppies are only a few days old, but already really cute and fun to watch. They're a little bit bigger than my hand, and very feisty and wriggly. At this stage they're all about sleeping and nursing on mom. In a few short weeks the six little puppies will be up walking around and tumbling all over each other. It'll be cool to go back and see them again in a week or so to see how they've grown. It was so much fun to watch them.

Tape to tape

Sometimes there are little side projects I help tackle just because they're interesting.

So at work we've got this LTO tape library that's used for archiving images. We're in the process of migrating off the tape library onto SAN and an IBM Tivoli tape library. In the meantime, there are a handful of older tapes (that we've found so far) that the LTO library has managed to mangle over the past few years. Fortunately it's just the leader section of the tape that's been mangled or broken, so we don't think there's been any actual data loss.

It's only a small number of tapes out of the hundreds of so in the library, so it probably wouldn't be a problem if the data on the tapes wasn't recoverable. Naturally the easy thing to do would be to send the tapes to one of those data recovery services and have them do the salvage work. But, that costs big bucks and being a Department of Very Little Budget, it's a last resort option.

What we do have are a bunch of spare LTO drives and a bunch of unused Sun Ultra servers. *ding*!, on comes the light bulb and we figure if we can connect the LTO drives to one of the Ultras, we can copy one tape to the other using dd(1)! Brilliant! Then we can brag about saving the department thousands of dollars!

Only if it works.

Found a couple of spare molex connectors in the Ultra box to provide power to the drives, and a SCSI cable lying around (just need to find one more now). The tape drives are high voltage differential SCSI-3. I'm not sure what the computer's SCSI card is, but with my luck it's the low voltage version.

So that's where we are now. One LTO drive connected and scrounging around for another SCSI cable to connect the other one. Might end up having to scrounge up some HVD SCSI cards too. Who knows. I have no idea if this will even work but it will be very cool if it does.

Things to do, geeks to meet

A few things coming up on the calendar.

Just heard about an attempt to revive a local Linux Users Group that's supposed to be meeting tomorrow at the main branch of the library. A chance for local Linux geeks to get together and meet. Might try to see if I can make it to that and see what kind of people are about.

Heather's trying to get a blogger Happy Hour gathering going next week at The Dog & Duck over in Mt P. From the comments so far, it looks like Tuesday might be the night. Should be fun.

The end of another storm season

Today is the last day of the 2006 hurricane season, and it has thankfully been a good deal calmer than last year. Out of a forecast of 12-15 named storms, this year we ended up with 9 named storms (4 tropical storms and 5 hurricanes).

I'm glad this year was a bit of a non-event storm wise. It was a good break from last year's hectic season. Hopefully next year will be more of the same. 6 months to relax a bit before the 2007 season starts up.

Package irradiation

I've been doing a little bit of liason work between one of the clinical research coordinators at work and K & S Associates. Someone decided to check out the radiation exposure patients were getting from a particular CT study and ordered some TLD chips for the measurement. Had they consulted us first, we'd have told them it probably wasn't the best way to get the dosimetry data, but they'd already ordered them.

So calibration chips were irradiated with a measured amount of radiation, and the rest were attached to patients who were then scanned. Then they were sent back for reading.

Normally a report is issued back in a couple of days, but this time there were some strange results. The charge readings K & S were getting were rather low (not surprising considering the amount of exposure they were getting) and somewhat inconsistent. TLD's normally aren't used for this kind of application either, so the charge stored on the chips was pretty close to the low end of their ability to read reliably. Normally these TLD chips are used to measure therapy doses, which are several orders of magnitude higher than what they would have been exposed to for this project.

So in the course of investigating the discrepancies, and several phone calls to me to confirm the calibration conditions, the tech at K & S learned that both UPS and FedEx have started running all the packages they handle through an x-ray scanner (one of those DHS screening things I'm sure).

The dose to the packages is far from trivial either. The K & S guy figured the TLD chips got anywhere from 0.5 to 1 cGy (50-100 mrad), which is about the radiation you'd get from 3 or 4 chest x-rays. With the TLD exposures the K & S are used to seeing, this amount of radiation is pretty negligible, but relative to the exposures we were using it's pretty honkin' big and can definitely skew the results in a big way.

For most packages this is hardly anything to be worried about, but for radiosensitive things like TLD chips and film it can be problematic. Photographic film, likely a non-issue, although perhaps some minor fogging possible.

Bottom line, if you're shipping anything radiosensitive or photosensitive, UPS/FedEx might not be the best choices.