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.
Tomorrow afternoon I get to go fishing for the first time with a friend of mine from work. The plan is to head out to some area called Dynamite Hole to catch some sharks and then go from there.
The thought occurred to me while I was writing this: How much irony is there in the fact that I’m going fishing after my volunteer shift at the Aquarium?
Nala and Simba both have their own crates in the bedroom that they sleep in. Now that they’re older, I can leave the doors open and let them sleep where they want. Nala usually walks into her crate for the night while Simba usually flops down on the floor somewhere.
The last couple of nights though, they’ve been sharing the same crate at night. Simba just walks in there, curls up in the back and uses Nala for a pillow. She doesn’t seem to mind the company and hasn’t kicked him out yet or anything. It’s kind of cute to see them both in there.
So what is it with people who bring their dog to the dog park, and then spend the entire time yakking on their cell phone instead of playing with their dog?
Dog park isn’t supposed to be just another place to ignore your dog. It’s supposed to be a place where they can go meet and play with other dogs and where you can go have fun playing with your dog and let them run around without worrying that they’ll run out onto the street and get hit by a car or something.
Gotta wonder about some pet owners sometimes.
Physics Corner was a series of articles I wrote for an incarnation of the department newsletter between 2000 – 2001. They’re collected here for posterity and maybe to provoke me into starting it up again as an online column.
A common attitude in diagnostic radiology is that most procedures are relatively safe and carry very little risk of causing further harm to patients. For the most part, this is true. However, some may be surprised to learn that in recent history, there have been several documented cases of radiation induced skin injury to patients resulting from prolonged fluoroscopic procedures. In fact, an advisory was issued by the FDA in 1994 warning of the potential for radiation injury resulting from prolonged fluoroscopic procedures such as PCTA, stent placements, ERCP, cath lab procedures and RF ablations. The text of the advisory is available online at http://www.fda.gov/cdrh/fluor.html for those interested in reading it.
The first effect of excessive radiation exposure to the skin is erythema (skin reddening). Erythema, which has a threshold of 200-600 rad (2-6 Gy), looks just like a sunburn and often has the same shape as the x-ray beam (circular or square). For an average sized patient, the skin entrance exposure rate to the patient can vary between 4-7 R/min (35-60 mGy/min), depending on the projection angle, size of the patient and type of tissue in the field. At these typical exposure rates, the threshold for skin erythema can be reached with less than an hour of fluoro time. For cine runs, patient exposure is even higher, around 50-100 R/min (440-875 mGy/min), and the skin erythema threshold can be reached with a few minutes of cine.
In the majority of fluoroscopic studies performed, the radiation exposure to the patient is well below the threshold for inducing skin erythema. However, even with today’s technology, the potential exists for radiation induced skin damage to a patient, and it is this potential that every fluoroscopist should be aware of when performing a procedure on a patient.
The table below, taken from http://hna.ffh.vic.gov.au/phb/hprot/rsu/pubs/fluoro2.html, summarizes a few recent incidents in which patients received radiation injuries from their procedures.
| Patient Sex and Age, country | Procedure | Nature of Injury | Fluoroscopic Exposure Time and Skin Dose |
|---|---|---|---|
| Female, 53, New Zealand (1996) | coronary angiography followed by coronary angioplasty | skin lesion | 101 minutes, 78 cinefluorography runs, 18 Gy |
| Female, 25, USA | RF cardiac catheter ablation | skin breakdown 3 weeks post procedure | unknown, procedure time of 325 minutes |
| Female, 62, USA | balloon dilation of bile duct anastomosis | burn-like back injury on back requiring skin graft | unknown |
| Female, 61, USA | renal angioplasty | skin necrosis requiring skin graft | unknown, procedure time of 165 minutes |
A very interesting case study can be found at http://www.fda.gov/cdrh/rsnaii.html discussing one particular incident of radiation injury from a coronary angioplasty procedure.
There are several methods that operators can use to minimize the radiation exposure to themselves and the patient:
Well, this is interesting. The National Hurricane Center has given that storm system swirling off the coast a name, Andrea, making it the first named storm of the season almost a month before the 2007 hurricane season officially starts.
AT 11 AM EDT…1500 UTC…A TROPICAL STORM WATCH HAS BEEN ISSUED ALONG THE SOUTHEAST COAST OF THE UNITED STATES FROM ALTAMAHA SOUND GEORGIA SOUTHWARD TO FLAGLER BEACH FLORIDA. A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE POSSIBLE WITHIN THE WATCH AREA…GENERALLY WITHIN THE NEXT 36 HOURS.
ANDREA IS MOVING GENERALLY TOWARD THE WEST NEAR 3 MPH. A CONTINUED SLOW MOTION AND A GRADUAL TURN TOWARD THE SOUTHWEST ARE EXPECTED DURING THE NEXT 24 HOURS. ALONG THIS TRACK…THE CENTER OF ANDREA IS EXPECTED TO REMAIN OFFSHORE OF THE U.S. COAST THROUGH AT LEAST THURSDAY MORNING.
According to the National Weather Service radar, there’s a narrow but intense band of rain that looks to be heading our way within the next hour or so, so it looks like it’s going to be a wet afternoon.