Guest guest Posted January 7, 2002 Report Share Posted January 7, 2002 Hi, I went off my levoxyl today to prepare for my first scan. My doc will do the 123I scan and up to it decide if and how much RAI I need. He explained to me that the 2 mCi dose of 123I doesn't cause " stunning " and that I'll be able to do the RAI soon after the scan. Has anybody done the 123I scan and tell me about how it was? I wanted to know why I have to take the 123I 2 days prior to the scan and what precautions I have to take during these 2 days at home. (I have young kids). How can I clean cloth/shoes after scan/RAI treatment? Are white TUMS ok for LID diet as calcium supplement? Thank, Naama TT November 2001. Bifocal bilateral well-differentiated Papillary microcarcinoma. Probably no lymph nodes involved. Hashimoto, TGab, TPab. off T4 preparing for 1st scan. Quote Link to comment Share on other sites More sharing options...
Guest guest Posted January 7, 2002 Report Share Posted January 7, 2002 > Hi, > > I went off my levoxyl today to prepare for my first scan. > My doc will do the 123I scan and up to it decide if and how much RAI > I need. He explained to me that the 2 mCi dose of 123I doesn't > cause " stunning " and that I'll be able to do the RAI soon after the > scan. > > Has anybody done the 123I scan and tell me about how it was? I've had 2 I123 scans.. you take a pill, a day later you come back for a scan.. no big deal, i was given no precautions. > > I wanted to know why I have to take the 123I 2 days prior to the scan > and what precautions I have to take during these 2 days at home. (I > have young kids). they give you the pill ahead of time so you are not too hot for the camera and so it has time to be uptaken (is that a verb) by the thyroid tissue. > > How can I clean cloth/shoes after scan/RAI treatment? regular laundry.. i've never worried about shoes.. > > Are white TUMS ok for LID diet as calcium supplement? yeah, but there are better calcium suppliments for LID, anything thats not oyster shell should be ok > > Thank, > > Naama > > TT November 2001. > Bifocal bilateral well-differentiated Papillary microcarcinoma. > Probably no lymph nodes involved. > Hashimoto, TGab, TPab. > off T4 preparing for 1st scan. Quote Link to comment Share on other sites More sharing options...
Guest guest Posted January 7, 2002 Report Share Posted January 7, 2002 Naama, Barb's answer was so much more to the point, but since I already have this ready to send, I'll post it anyway :-) I haven't had I123, so cannot speak from personal experience. Is there a particular reason why you are receiving I123 instead of I131? My impression is that it is still largely in the research stages. Do you know if you are part of a research study? I'm surprised that you will have your scan 2 days after receiving the I123; my understanding is that because it has a much shorter half-life, scanning is generally done the same day. And because the half life is much shorter, you will not have to isolate yourself for as long a period of time as with I131 (although I don't know how much longer; I've never seen that addressed). The most frequent advice is to keep your laundry separate from everyone else's, and run it through the washer twice (which also helps clean out the washer for your family's stuff), although I believe Ian has said that a single run through the washer is sufficient. I can't answer about the shoes. TUMS are fine on the LID; they do not contain iodine. Even the red-colored tablets use food colors which are permitted (Red 27 Lake, Red 30 Lake) as opposed to Red #3, which is not permitted. I have copied below some letters regarding I-123, which give a lot more detail. good luck with the LID and with your scan- - NYC (TT 2/99 dx pap/foll; RAI 100 mCi 3/99 & 4/00; current TSH ~.06 on .225 levothyroxine) --------------------------------------------------------------------------------\ --------- consolidated letters from , MD, nuclear medicine: I-131 and I-123 uptakes are identical. An uptake performed with one isotope will give a value the same as the other, except for statistical error. In my clinic the normal values for someone WITH A THYROID are 5-12% at 2 hours and 10-35% at 24 hours. In my clinic the " normal " value for a thyroid cancer patient after a successful ablation is <0.3%. These numbers are somewhat dependent upon the methods used to measure uptake and so you should check with the clinic that performed the uptake for the exact normal range. ------------------------------- I-123 may or may not be a better than I-131 for scanning. There is no way anyone can promise you that I-123 will be beneficial in the long run. The possible advantages of I-123 are 1. Better images because gamma camera are better tuned to the photon energy of I-123 than the photon energy of I-131. 2. Absence of stunning The possible disadvantages of I-123 are: 1. Worse images because imaging is performed at 24 hours instead of 72 hours. Because of the relatively short half-life of I-123 (12 hours for I-123 versus 8 days for I-131) Note that with I-131 72 hour images are definitely better than 24 hour images.) 2. Higher cost by a factor of about 100 Will the better images due to photon energy outweigh the poorer images due to earlier imaging? We don't know yet. That is why physicians are conducting research studies. The main risk that you take is that the I-123 scan will fail to show something that would have affected the treatment dose. What is the risk of that? In my experience, the results of a pre-therapy scan affect the treatment dose in fewer than 1 in 5 patients. Depending on whether I-123 is 100% inaccurate, which I doubt, or 100% accurate will determine your risk. ------------------- The ability to detect thyroid cancer depends in part on " image contrast " . Image contrast is based on the amount of uptake in the " target " tissue (thyroid cancer) relative to the among of radioactivity in the " background " (surrounding non-thyroid tissue). You can have better image contrast by increasing the amount of uptake in the thyroid cancer or decreasing the amount of radioactivitiy in the background tissue. Most people excrete about 60% of a dose of radioiodine (I-131 or I-123) over 24 hours and about 85% of a dose over 48 hours and 95% of a dose over 72 hours. So about 40%, 15% and 5% are remain in the body at 24, 48 and 72 hours, respectively. That remaining amount contributes to background radioactivity. So the best way to improve image contrast is to wait a longer period of time for excretion of iodine unbound to thyroid cancer. The problem with waiting longer is primarily radioactive decay. With I-131 this is not much of a problem. I-131 has a half-life of 8 days so at the end of 3 days, just 23% of the administered radioactivity is lost due to physical decay. With I-123 this is a much bigger problem. At the end of 24 hours, 73% of the radioactivity is lost due to physical decay, at the end of 48 hours 94% of the radioactivity is lost to decay and at 72 hours over 98% of the radioactivity is lost to decay. So 72 hour imaging is not an option for I-123, unless we start giving people 30 mCi of I-123 for imaging. Again with I-131 we know that 72 hour images have better contrast than 24 hour images and therefore can detect more thyroid cancer. I would expect the same to be true with I-123 if one gave enough of a dose to overcome physical decay. This has to be balanced against the fact that modern gamma camera images I-123 better than I-131. To a modern gamma camera 1 mCi of I-123 in the body looks like 10 mCi of I-131. Will the improved images with I-123 outweigh the problem of having to take images at 24 hours? This is a question that research must answer. Stunning is injury to the thyroid from a scanning dose that prevents a subsequent treatment dose from working. I monitor all of my patients for stunning. It is an extremely rare problem when scanning dose are kept at 2.5 mCi or less. Stunning only occurs because of the therapeutic effects of I-131. I-123 has no therapeutic radiation (beta radiation), so stunning should not occur with I-123. --------------------------- --------------------------------------------------------------------------------\ -------------- and from Ian Adam, Radiation Safety Officer: From a patient's point of view (any patient, not just thycan), 123I is also quite good. It has a short half-life (13h instead of 8 days) so precautions are fewer and lifted sooner. The only real disadvantage of the stuff is that it is costlier than 131I. .... Millicurie for millicurie, 123I gives a much lower dose. For a person with a thyroid, 123I is much better. For someone without a thyroid, there's not much to choose. ------------------------------------------------ .... and this from a very knowledgeable list member (but not an MD): Iodine 123 - unstable. Emits gamma radiation only. Atomic half life about 13 hours. Is an alternative for gamma scanning. Can not be used for treatment because it does not emit beta radiation. The advantage is that it does not cause stunning. The disadvantage is that the short half life makes it difficult to administer correctly, more expensive and can only be used for scanning for a shorter period while the Iodine is still all over the digestive and other systems causing confusion. naamapaca wrote: > Hi, > > I went off my levoxyl today to prepare for my first scan. > My doc will do the 123I scan and up to it decide if and how much RAI > I need. He explained to me that the 2 mCi dose of 123I doesn't > cause " stunning " and that I'll be able to do the RAI soon after the > scan. > > Has anybody done the 123I scan and tell me about how it was? > > I wanted to know why I have to take the 123I 2 days prior to the scan > and what precautions I have to take during these 2 days at home. (I > have young kids). > > How can I clean cloth/shoes after scan/RAI treatment? > > Are white TUMS ok for LID diet as calcium supplement? > > Thank, > > Naama > > TT November 2001. > Bifocal bilateral well-differentiated Papillary microcarcinoma. > Probably no lymph nodes involved. > Hashimoto, TGab, TPab. > off T4 preparing for 1st scan. Quote Link to comment Share on other sites More sharing options...
Guest guest Posted January 8, 2002 Report Share Posted January 8, 2002 Naama After taking RAI - any isotope - it circulates in the bloodstream until it is taken up by the thyroid or excreted by the kidneys. The longer you wait, the clearer the picture will be. Unfortunately, the half-life of 123I is so short that you can't wait longer than 2 days otherwise there won't be anything left to scan. 123I is most often used for scanning 'thyroids' (as opposed to 'no thyroids' as with THYCA patients), when you can get enough uptake between early morning and late afternoon, or after 24 hours, to get a useful image. A major disadvantage of 123I is that it is very expensive to produce, so it isn't used that often. A major advantage is that it is much, much safer than 131I and needs none of the precautions that are usual for 131I. You need take no special precautions with your clothing after a few mCi of 123I. Ian > > I wanted to know why I have to take the 123I 2 days prior to the scan > and what precautions I have to take during these 2 days at home. (I > have young kids). > > How can I clean cloth/shoes after scan/RAI treatment? > > Are white TUMS ok for LID diet as calcium supplement? > > Thank, > > Naama > > TT November 2001. > Bifocal bilateral well-differentiated Papillary microcarcinoma. > Probably no lymph nodes involved. > Hashimoto, TGab, TPab. > off T4 preparing for 1st scan. > > > > > For more information regarding thyroid cancer visit www.thyca.org. If you do not wish to belong to this group, you may UNSUBSCRIBE by sending a blank email to thyca-unsubscribe > > > Quote Link to comment Share on other sites More sharing options...
Guest guest Posted January 8, 2002 Report Share Posted January 8, 2002 Looks like Ian answered your questions, but thought I would send a post I saved from Dr. regarding I-123 v. I-131 to give you additional info. The original poster, asking the question about I-123 was from Australia....are you also from somewhere other than the US, Naama? Marilyn (dx '94-pap w/lung metastases - 5 pos scans/435mCi's - scans 6 & 7 clean) *****From Dr. in response to questions about I-123******** Subject: Re: Iodine 123 -trial help Date: Thu, 08 Jun 2000 13:32:23 -0400 Kaaren, I-131 is the gold standard for the detecting the site and extent of thyroid cancer. 99m-Technetium pertechnetate is a good agent for detecting normal thyroid tissue, but is an extremely poor agent for detecting small amounts of thyroid tissue (such as after a thyroidectomy) or for detecting thyroid cancer. Using a 99m-Technetium pertechnetate scan alone as a pre-abaltion test is very close to using no scan at all before an ablation. To be fair, some physicians perform no pretherapy scan on thyroid cancer patients and routinely treat all post-thyroidectomy patients with 75-150 mCi. I-123 may or may not be a better than I-131 for scanning. There is no way anyone can promise you that I-123 will be beneficial in the long run. The possible advantages of I-123 are 1. Better images because gamma camera are better tuned to the photon energy of I-123 than the photon energy of I-131. 2. Absence of stunning The possible disadvantages of I-123 are: 1. Worse images because imaging is performed at 24 hours instead of 72 hours. Because of the relatively short half-life of I-123 (12 hours for I-123 versus 8 days for I-131) Note that with I-131 72 hour images are definitely better than 24 hour images.) 2. Higher cost by a factor of about 100 Will the better images due to photon energy outweigh the poorer images due to earlier imaging? We don't know yet. That is why physicians are conducting research studies. The main risk that you take is that the I-123 scan will fail to show something that would have affected the treatment dose. What is the risk of that? In my experience, the results of a pre-therapy scan affect the treatment dose in fewer than 1 in 5 patients. Depending on whether I-123 is 100% inaccurate, which I doubt, or 100% accurate will determine your risk. Again, the purpose of the research study is to find out what that risk is, if any. How will you be managed if you do not take part in the research study? Will you get an I-131 scan or a 99m-Technetium pertechnetate scan? Jeff kaaren peterson wrote: > Dear Thycans, > I have been asked to take part in a pilot study on the use of Iodine > 123 for post operative scans and I would love some input. A nuc med > fellow rang me from my hospital and said that it is used in other > hospitals in Sydney and in the US but my hospital had only just > approved a trial of ten patients. He is having trouble getting > people to volunteer and is only up to number 3. > He feels there is a better image with 123 but he has to prove it. > My doubt is that they want me to do the regular technetium-99m > Pertechnetate scan ( a radioactive Iodine equivalent) on the Monday > and then come back on the Wednesday and do the Iodine 123 with one > scan of the neck 4-6hours later and then 24hrs later a whole body > scan..... and then the big ablative dose a day or so after that. > He says that the radiation dose of the 123 is a little less than the > usual 131 test and that they don't expect any side effects or > interference with the ablative dose. > I am full of doubt even though they have tried to pitch it to me as > having an ultimate long term benefit to me. > They say I have to have the second scan because they aren't allowed > by the hospital to use the 123 as a diagnostic tool until it passes > this trial. > On the one hand I figure I am probably going to be zapped so heavily > with the ablative dose it wont matter - just 2 more days hypo. > On the other I don't trust anyone much anymore and am very keen to > find more info..... I will have a long chat with my new wonderful > endo, but am interested in anyone elses' perspective. > > Ian what do you think? Is this your area? > Many thanks, > Kaaren > tt & selective neck dissection pap thyca 4/00, rai 6/00 > -- A. , MD Nuclear Medicine, A-72 (Fax) Albany Medical Center (Beeper) Albany, NY 12203 cooperj@... > I went off my levoxyl today to prepare for my first scan. > My doc will do the 123I scan and up to it decide if and how much RAI > I need. He explained to me that the 2 mCi dose of 123I doesn't > cause " stunning " and that I'll be able to do the RAI soon after the > scan. > > Has anybody done the 123I scan and tell me about how it was? > > I wanted to know why I have to take the 123I 2 days prior to the scan > and what precautions I have to take during these 2 days at home. (I > have young kids). > > How can I clean cloth/shoes after scan/RAI treatment? > > Are white TUMS ok for LID diet as calcium supplement? > > Thank, > Naama > > TT November 2001. > Bifocal bilateral well-differentiated Papillary microcarcinoma. > Probably no lymph nodes involved. > Hashimoto, TGab, TPab. > off T4 preparing for 1st scan. Quote Link to comment Share on other sites More sharing options...
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