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From: Androcles on 16 Jan 2010 19:10 "Joerg" <invalid(a)invalid.invalid> wrote in message news:7rephiFdn6U1(a)mid.individual.net... > Androcles wrote: >> "Joerg" <invalid(a)invalid.invalid> wrote in message >> news:7remmlFu8dU3(a)mid.individual.net... >>> Androcles wrote: >>>> "Joerg" <invalid(a)invalid.invalid> wrote in message >>>> news:7rek2jFd03U2(a)mid.individual.net... >>>>> Androcles wrote: >>>>>> "Joerg" <invalid(a)invalid.invalid> wrote in message >>>>>> news:7rej86Fd03U1(a)mid.individual.net... >>>>>>> Androcles wrote: >>>>>>>> "RichD" <r_delaney2001(a)yahoo.com> wrote in message >>>>>>>> news:524e9de7-330d-40fd-90f5-0d671ec9ce7d(a)j19g2000yqk.googlegroups.com... >>>>>>>>> is it possible to design a subcutaneous x ray? >>>>>>>>> A surgeon might want to see a depth just below >>>>>>>>> where he intends to cut. >>>>>>>>> >>>>>>>>> The point is, I thought only bones are opaque to x rays. >>>>>>>> The problem is focus. >>>>>>>> Hold a page of text up at normal reading distance and focus on a >>>>>>>> few words. Note that background and peripheral objects, although >>>>>>>> noticeable, are out of focus. Now focus on a background object and >>>>>>>> note that the writing on the paper is no longer in focus. All >>>>>>>> lenses, including those in your eyes, have limited distances or >>>>>>>> ranges in which two objects on different planes (focal planes) may >>>>>>>> be simultaneously in focus. >>>>>>>> The solution has been MRI. >>>>>>>> >>>>>>> Ultrasound machine had dynamic focusing since the 70's :-) >>>>>>> >>>>>>> What this means is "on-the-fly" focusing, like a lens that bends to >>>>>>> the correct shape while the echoes are coming back from deeper and >>>>>>> deeper regions. Easy on receive, but for transmit you need to do >>>>>>> several shots and stitch the resulting horizontal image slices >>>>>>> together. That's a whole science unto itself but nowadays very much >>>>>>> standard procedure. >>>>>> Yes, I wouldn't doubt it. I have no medical degree and very little >>>>>> knowledge in that field, my only use of ultrasound has been >>>>>> in an electronics cleaning bath. My experience with MRI is a >>>>>> yearly check up when I'm injected with something that makes me >>>>>> feel hot and want to pee! >>>>>> Thanks for the info. >>>>>> >>>>> Yearly? Wow! I was never in an MRI, so far. One reason why ultrasound >>>>> is preferred is that MRI is hugely expensive while an ultrasound scan >>>>> is typically reimbursed at the two-digit Dollar level. MRI is usually >>>>> four-digit. >>>>> >>>>> The underlying reason is equipment cost. A good MRI machine costs >>>>> millions while a decent ultrasound scanner can be had for under $50k. >>>>> >>>> I have had a stent in my aorta since 2007. >>>> I suppose it is worth 4 digits to make sure it hasn't moved, it cost >>>> enough to put it there. >>>> >>>> >>>> http://www.web-books.com/eLibrary/Medicine/Cardiovascular/Images/aneurysm_aortic.jpg >>>> >>>> http://cvm.msu.edu/hospital/services/interventional-radiology/ir-media/Tracheal%20Stent.jpg >>>> >>> Oh yeah, got to be careful. Glad that they caught yours in time since >>> aortic aneurysms are generally symptom-less. With a friend of ours it >>> happened on a golf course, too late :-( >>> >> >> If sudden intense back pain while sitting relaxed at the computer is >> symptom-less then I would hate to find out what a symptom is. :-) > > > Problem is, that many people (like myself) have those shooting back pains > come up for the usual reasons. "Floppy disks", as some folks in the south > would say ... > > >> I went to lay on the bed but it wasn't easing after 30 minutes so I >> called an ambulance. At least I finished the post I was writing. >> > > You were very lucky. Our friend was calmly standing there looking at a > golf shot someone did. Then he just fell over, and that was it. Another > friend had one in brain blood vessels but she survived. She said she felt > absolutely nothing, just blacked out. Luckily they had a meeting and the > guy next to her caught her head before it hit the table and another dialed > 911 milliseconds later. > I was fully conscious, just in agony. Doc asked me if it was the worst pain I'd ever experienced.... I said no, I had a shattered ankle with bone protruding in 2002 and a nurse immobilised it, but it came a close second.
From: Bill Sloman on 16 Jan 2010 19:21 On Jan 16, 4:54 am, Salmon Egg <Salmon...(a)sbcglobal.net> wrote: > In article > <524e9de7-330d-40fd-90f5-0d671ec9c...(a)j19g2000yqk.googlegroups.com>, > > RichD <r_delaney2...(a)yahoo.com> wrote: > > is it possible to design a subcutaneous x ray? > > A surgeon might want to see a depth just below > > where he intends to cut. > > > The point is, I thought only bones are opaque to x rays. > > > -- > > Rich > > X-ray absorption is approximately proportional to the square of the > atomic number. There just is not much to be found under the skin near > the Z = 20 of calcium. There is not enough potassium with Z=19. Iron in > blood has Z = 28 but is only a small portion of hemoglobin. Iodine, > often used as an x-ray contrast medium. is also scarcer in the body. X-ray tomography (body-scan) does pick up soft-tissue absorbtion. A complete body-scan used to be 45 of the median lethal X-ray dose, but for an arm, leg or head you can get by with a substantially lower dose. Magnetic resonance imaging is much less dangerous, but even more expensive. -- Bill Sloman, Nijmegen
From: John Larkin on 16 Jan 2010 19:44 On Sat, 16 Jan 2010 16:21:00 -0800 (PST), Bill Sloman <bill.sloman(a)ieee.org> wrote: >On Jan 16, 4:54�am, Salmon Egg <Salmon...(a)sbcglobal.net> wrote: >> In article >> <524e9de7-330d-40fd-90f5-0d671ec9c...(a)j19g2000yqk.googlegroups.com>, >> >> �RichD <r_delaney2...(a)yahoo.com> wrote: >> > is it possible to design a subcutaneous x ray? >> > A surgeon might want to see a depth just below >> > where he intends to cut. >> >> > The point is, I thought only bones are opaque to x rays. >> >> > -- >> > Rich >> >> X-ray absorption is approximately �proportional to the square of the >> atomic number. There just is not much to be found under the skin near >> the Z = 20 of calcium. There is not enough potassium with Z=19. Iron in >> blood has Z = 28 but is only a small portion of hemoglobin. Iodine, >> often used as an x-ray contrast medium. is also scarcer in the body. > >X-ray tomography (body-scan) does pick up soft-tissue absorbtion. A >complete body-scan used to be 45 of the median lethal X-ray dose, but >for an arm, leg or head you can get by with a substantially lower >dose. > >Magnetic resonance imaging is much less dangerous, but even more >expensive. I had a head MRI, noisy and boring. I think the official price was $6000, but I paid $20. John
From: Michael A. Terrell on 16 Jan 2010 20:21 John Larkin wrote: > > On Sat, 16 Jan 2010 16:21:00 -0800 (PST), Bill Sloman > <bill.sloman(a)ieee.org> wrote: > > >On Jan 16, 4:54 am, Salmon Egg <Salmon...(a)sbcglobal.net> wrote: > >> In article > >> <524e9de7-330d-40fd-90f5-0d671ec9c...(a)j19g2000yqk.googlegroups.com>, > >> > >> RichD <r_delaney2...(a)yahoo.com> wrote: > >> > is it possible to design a subcutaneous x ray? > >> > A surgeon might want to see a depth just below > >> > where he intends to cut. > >> > >> > The point is, I thought only bones are opaque to x rays. > >> > >> > -- > >> > Rich > >> > >> X-ray absorption is approximately proportional to the square of the > >> atomic number. There just is not much to be found under the skin near > >> the Z = 20 of calcium. There is not enough potassium with Z=19. Iron in > >> blood has Z = 28 but is only a small portion of hemoglobin. Iodine, > >> often used as an x-ray contrast medium. is also scarcer in the body. > > > >X-ray tomography (body-scan) does pick up soft-tissue absorbtion. A > >complete body-scan used to be 45 of the median lethal X-ray dose, but > >for an arm, leg or head you can get by with a substantially lower > >dose. > > > >Magnetic resonance imaging is much less dangerous, but even more > >expensive. > > I had a head MRI, noisy and boring. I think the official price was > $6000, but I paid $20. I had one at the VA hospital when I had 'Bell's Palsey in my right eye. I agree with you about the noise. I had a throbbing headache for several days. My copay was $0. -- Greed is the root of all eBay.
From: Michael A. Terrell on 16 Jan 2010 20:23
Androcles wrote: > > I was fully conscious, just in agony. Doc asked me if it was the worst > pain I'd ever experienced.... I said no, I had a shattered ankle with bone > protruding in 2002 and a nurse immobilised it, but it came a close second. I sat through almost three full hours of Oral Surgery without any painkiller, while in the US Army. The surgeon wanted to know how I kept from passing out. -- Greed is the root of all eBay. |