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From: wc on 17 Jan 2010 06:37 On Jan 16, 9:05 pm, Phil Hobbs <pcdhSpamMeSensel...(a)electrooptical.net> wrote: > On 1/16/2010 5:31 AM, Androcles wrote: > > > "RichD"<r_delaney2...(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. > > There are lots of solutions to this. In optical microscopy, you can > take images at several depths and combine them, choosing the level that > shows the most contrast at each position. Zeiss has been selling > systems like that for years. > > In confocal microscopy(*), you can just sum the images taken from > different depths, since out-of-focus planes hardly contribute to the > image at all. > > There's also phase-coded imaging, which uses an artistically designed > phase plate to allow 3D reconstruction from a single image. (It's > really a beautiful technique, which I'd like to understand better than I > do.) > > So the old classical optics limitations are being overcome all over the > place. > > Cheers > > Phil Hobbs > > (*)My thesis was on a phase sensitive laser scanning confocal > microscope, and I helped invent the modern real-time confocal. > > -- > Dr Philip C D Hobbs > Principal > ElectroOptical Innovations > 55 Orchard Rd > Briarcliff Manor NY 10510 > 845-480-2058 > > email: hobbs at electrooptical dot nethttp://electrooptical.net Dr. Hobbs; Can you tell me if "phase-coded imaging" is the same as "single lens 3- D"? If so, then that is something which I came up with in the 60's, and patented in the 80's. Such an image may be phase-coded, time-coded, frequency-coded, or encoded in any way which will allow some differentiation at some sensor.
From: jmfbahciv on 17 Jan 2010 09:24 Androcles wrote: > "Michael A. Terrell" <mike.terrell(a)earthlink.net> wrote in message > news:4B5266A5.C29D3EF6(a)earthlink.net... >> 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. >> > Eventually the morphine put me to sleep, but I don't believe it does > anything for real pain. > It depends on the pain source. Morphine works for some things; other kinds of drugs work for other kinds of pain. Talk with a hospice nurse if you're really curious. /BAH
From: Bill Sloman on 17 Jan 2010 12:38 On Jan 17, 3:28 am, "Tim Williams" <tmoran...(a)charter.net> wrote: > "Bill Sloman" <bill.slo...(a)ieee.org> wrote in message > > news:a1709d71-1e31-4a63-99c8-987091561fd6(a)21g2000yqj.googlegroups.com... > > > 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 ... > > 45%? That sounds warm. It's wrong. It should have been 4%. On my keyboard "%" is upper-case "5". I remember getting it wrong, but I thought that I'd corrected it. Sorry. -- Bill Sloman, Nijmegen
From: Bill Sloman on 17 Jan 2010 12:48 On Jan 16, 9:56 pm, "Androcles" <Headmas...(a)Hogwarts.physics_r> wrote: > "Joerg" <inva...(a)invalid.invalid> wrote in message > > news:7remmlFu8dU3(a)mid.individual.net... > > > > > > > Androcles wrote: > >> "Joerg" <inva...(a)invalid.invalid> wrote in message > >>news:7rek2jFd03U2(a)mid.individual.net... > >>> Androcles wrote: > >>>> "Joerg" <inva...(a)invalid.invalid> wrote in message > >>>>news:7rej86Fd03U1(a)mid.individual.net... > >>>>> Androcles wrote: > >>>>>> "RichD" <r_delaney2...(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/aneu.... > > >>http://cvm.msu.edu/hospital/services/interventional-radiology/ir-medi.... > > > 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. :-) > 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. The trouble with aortic aneurysms is that they are symptonless until they start dissecting. Once that has started, the the mortality rate is about 20% per hour. The half hour wait until you called an ambulance wasn't a good idea. A useful clue is that the pain is synchronised with the heart-beat - each heart-beat tears the tissue a little more. One of our friends survived a dissecting aoretic aneurysm, and he was a mine of information. -- Bill Sloman, Nijmegen
From: Androcles on 17 Jan 2010 13:27
"Bill Sloman" <bill.sloman(a)ieee.org> wrote in message news:2fded1fe-85df-4f03-a1dd-110ccd1a5e21(a)r5g2000yqb.googlegroups.com... On Jan 16, 9:56 pm, "Androcles" <Headmas...(a)Hogwarts.physics_r> wrote: > "Joerg" <inva...(a)invalid.invalid> wrote in message > > news:7remmlFu8dU3(a)mid.individual.net... > > > > > > > Androcles wrote: > >> "Joerg" <inva...(a)invalid.invalid> wrote in message > >>news:7rek2jFd03U2(a)mid.individual.net... > >>> Androcles wrote: > >>>> "Joerg" <inva...(a)invalid.invalid> wrote in message > >>>>news:7rej86Fd03U1(a)mid.individual.net... > >>>>> Androcles wrote: > >>>>>> "RichD" <r_delaney2...(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/aneu... > > >>http://cvm.msu.edu/hospital/services/interventional-radiology/ir-medi... > > > 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. :-) > 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. The trouble with aortic aneurysms is that they are symptonless until they start dissecting. Once that has started, the the mortality rate is about 20% per hour. The half hour wait until you called an ambulance wasn't a good idea. A useful clue is that the pain is synchronised with the heart-beat - each heart-beat tears the tissue a little more. One of our friends survived a dissecting aoretic aneurysm, and he was a mine of information. ============================================== The problem is, Bill, that one such as myself didn't know what it was and all the warnings published are for chest pain, not back pain, even though it is in the thorax. Eventually I'd decided it was probably heart attack related (wrong) and called for help based on that assumption. I've got some mild pain right now in the same place, right between the shoulder blades, but I'm fairly confident it is muscular and will ease if I lay down for a while; which I shall now do. |