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Journal Club: Radiation Exposure of Patients Undergoing Whole-Body Dual-Modality 18F-FDG PET/CT Examinations

It’s been a while since the last journal club article. Partly because I hadn’t come across too many articles I thought were interesting enough, mostly because I haven’t had much time to do much journal reading lately. And now from this month’s Journal of Nuclear Medicine come two articles that I found very interesting and informative.

The first one looks at radiation exposures to patients from combined PET/CT scans, an increasingly popular (and quickly becoming ‘standard of care’) method of diagnosing cancer and monitoring therapy efficacy. CT and PET radiation doses were examined at 4 hospitals each employing a variety of techniques: low-dose CT for attenuation correction, diagnostic CT for attenuation correction and localization, contrast and non-contrast studies. Total radiation dose came out to around 25 mSv (about 7 mSv from PET, 18 mSv from CT) and was surprisingly mostly independent of the protocol used.

A handy table of dose coefficients for various organs is also provided, which will make it easy to estimate the radiation dose to various organs from an exam given the injected activity and CTDI from the CT scan.

What was not clear was if any of the scanners had any of the CT dose reduction methods being used in the newest scanners (the ones that dynamically adjust tube current throughout the scan). These have been shown to effectively reduce patient dose while maintaining a desired image quality. I’m sure these methods incorporated into the newest PET/CT units can bring down the radiation dose a little more.

This ought to be a useful paper for any medical physicist or radiologist finding the need to estimate radiation dose from a PET/CT scan, or wanting to optimize their protocols to minimize dose.

Gunnar Brix, PhD, Ursula Lechel, MS, Gerhard Glatting, PhD, Sibylle I. Ziegler, PhD, Wolfgang Münzing, PhD, Stefan P. Müller, MD and Thomas Beyer, PhD, “Radiation Exposure of Patients Undergoing Whole-Body Dual-Modality 18F-FDG PET/CT Examinations“, JNM 46 608-613 (2005)


Abstract:

We investigated radiation exposure of patients undergoing whole-body 18F-FDG PET/CT examinations at 4 hospitals equipped with different tomographs. Methods: Patient doses were estimated by using established dose coefficients for 18F-FDG and from thermoluminescent measurements performed on an anthropomorphic whole-body phantom.
Results: The most relevant difference between the protocols examined was the incorporation of CT as part of the combined PET/CT examination: Separate low-dose CT scans were acquired at 2 hospitals for attenuation correction of emission data in addition to a contrast-enhanced CT scan for diagnostic evaluation, whereas, at the other sites, contrast-enhanced CT scans were used for both purposes. Nevertheless, the effective dose per PET/CT examination was similar, about 25 mSv.
Conclusion: The dosimetric concepts presented in this study provide a valuable tool for the optimization of whole-body 18F-FDG PET/CT protocols. Further reduction of patient exposure can be achieved by modifications to the existing hardware and software of PET/CT systems.

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Time to think about storm season

Mark Treadwell over at Geekswithblogs.net has a hurricane category with a bunch of good tips for preparing and suriving hurricane season.

Now that I’ll have a house to deal with this year, there will be a lot of work for me researching and acquiring the tools to storm-proof the house.

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Approaching the end of the house saga

It’s finally coming to the end. We’re going to end up closing a few weeks later and paying a bunch more in closing costs because of issues with the appraisal and getting that clarified.

First it started with the loan people contacting me asking why I hadn’t responded to their emails about the appraisal report. Since I never received the email with the appraisal report, and didn’t know the appraiser had gone back out there, naturally I was a little confused. So, a copy of the report was sent out again. Much to my surprise, the appraiser valued the house somewhat lower than the purchase price…$14 000 less. So then began a two week long exchange of recent sales figures, discussions and reviews of the appraisal, which didn’t end up changing anything in the end.

So after all that, there were two choices: walk away and start the house hunting process all over again, or cough up an extra $14 000 at closing to cover the difference between the purchase price and the appraised value. After all, the lender isn’t going to want to finance a house that costs more than someone thinks it’s worth. I know if I was a mortgage lender, I certainly wouldn’t.

Crap. $14 000 is going to be a lot to pull out of my pants. Well, I figure it’ll be short term pain, long term gain. We’ll be here at least for the next 4 years, location is pretty prime (10 minute commute to work in moderate traffic at the worst), nice big house, nice big yard. Even if after 4 years the appraised value only appreciates up to the original purchase price, I think we’ll have gotten our money’s worth (as long as a hurricane doesn’t take it out on us before then), and we’ll still have a some equity built up into it.

Still, it’s a little bit inconvenient though. One of the tips in all the house buying books we read was not to buy or build the most expensive house in the area for just this reason. I suppose if it’s the house you want and there aren’t any other comparable houses for sale where you want them, you just have to bite the bullet and go for it.

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Review: Babylon 5: The Complete Series

This is a fantastic DVD set. Babylon 5 was a cutting edge series when it came out nearly 10 years ago, and to me is still one of the best sci-fi series ever. But this isn’t about the series. Everyone knows the series was great and what it was all about.

The 5 season collection is pretty huge. With 6 DVDs and 22 episodes in each season, it’s a lot of TV watching. Nothing any die-hard B5 fan wouldn’t object to or find overly strenuous, especially since the entire series can be watched commercial free (with pauses for bathroom breaks and food of course)!

The slip cases for each season are nice and colourful and provide a very nice presentation for the series. Each season comes in a book-style cover with disk on each side of a plastic DVD disk holder. My only complaint with the boxed set is that the disk holders are simply glued in and not very solidly at that. Already I’ve had a two of the disk holders pop out of the covers when they got dropped (onto carpet). The cover is creased between each plastic holder to make for easy opening, but doesn’t seem like it will withstand a lot of opening and closing. It’s not likely to fall apart soon, but it seems to me the binding could have been done a little better and more solidly.

There are special features on disks 1, 4 and 6 of each season, which I haven’t had a chance to go through yet. 2 or 3 episodes in each season have commentary from JMS and others. The special features consist mostly of character, equipment and technology background in the form of ‘data files’. Gag reels are included in the last couple of seasons. A few short documentaries are also sprinkled here and there.

The series itself of course I give 5/5 to. The DVD collection I’ll have to give 4/5 to, mostly because of the relatively poor binding quality and ho-hum special features.

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Permanent residency status finally!

After a 2 1/2 year patient wait, we were summoned to the Charleston USCIS office (formerly INS) for my Adjustment of Status interview. Armed with my ream of paperwork (still ended up forgetting a couple of things), we headed off to their new location off Highway 7. A much nicer setting than their previous location on Meeting St, although not nearly as nice a view. Actually no view at all.

After a short wait (30 minutes or so), we met with the USCIS officer, told him our story, gave him the requested documentation, answered his questions and at the end I was rewarded with a stamp in my passport giving me permanent resident status (more colloquially known as the “green card”)! I’m told the actual card should be coming in 2-6 months. Hopefully it doesn’t get lost in the mail when we move.

Now I can live and work here without having to remember to renew this or that every year. Big weight taken off now that I don’t have to worry about it.

Now if I can only get this house thing wrapped up…but that’s a story for another post.