0 By aeadmin In Posted January 21, 2025Hello, If I understand the American Association of Physicists in Medicine (AAPM) report 293 correctly, the SSDE and CTDIvol values for children are approximately the same. This is because, as I understand it, the fH16 factor (conversion factor) is quite small even for newborn infants (e.g. between 0.9 and 1.05 for a one-year-old child). In fact, for children older than 1 year, the fH16 value becomes smaller and therefore the SSDE value also becomes smaller. This means, for example, that the CDTIvol value shown in the dose report of a 3-year-old child after a CT scan should actually be smaller. Please allow me to ask 4 questions about all this: 1- Is my summary above correct? 3- Is this formula correct to convert CDTIvol to SSDE? SSDE= fH16*CTDVol 3- How can I convert SSDE value to effective dose? 4- When we calculate with the conversion factors in the AAPM 204 report, sometimes there is a big difference between SSDE and CDTIvol, why do the conversion factors in the AAPM 293 report do not cause a big difference between SSDE and CTDIvol? Yours sincerely. READ MORE
0 By aeadmin In Posted January 21, 2025Hello, I want to calculate how much effective dose my child (6 months old, male) received as a result of a computed radiography scan he had in 2016. On the image, it is written “Stitching Spine AP”, however the image looks like a Pelvis scan actually. There is not much information in the DICOM outputs after the scan unfortunately, so I do not have kVp, mAs, grid, SID, filtration, beam collimation, DAP, ESD etc. information. But I saw in an article on the internet that the “exposure index (EI)” value is a parameter that can give an idea about the patient dose. I am copying the article link below: https://www.sciencedirect.com/science/article/pii/S107881742030050X The brand of the CR device on which the scan was performed is Konica Minolta (manufacturer model name: 0817 and station name: CS-2). In the DICOM outputs, the value of tag 0018,1405 (relative x-ray exposure) is given as 130. The value for tag 0018,6000 (sensitivity) is given as 250. As I understand from below links, these are the manufacturer-specific units of radiation dose measured on the detector (or imaging plate): https://dicomlookup.com/dicomtags/(0018,1405) https://www.dicomlookup.com/dicomtags/(0018,6000) I thought these were the tags I should focus on, and I tried to find radiation values corresponding to these units on the internet. I found an article which shows that the value of 130 in tag 0018,1405 for Konica Minolta corresponds to a rough estimate of 20μGy (0.02 mGy) of detector exposure. Article link is below, shown on table 2: https://pmc.ncbi.nlm.nih.gov/articles/PMC3076558/ As I understand it, this value is the value absorbed by the detector, not by patient. However, assuming that the patient dose would be similar, I tried to calculate the equivalent dose, and by setting the radiation weighting factor (Wr) to 1 (since it is X-ray), I calculated the equivalent dose as 0.02 mSv. For effective dose, organ/tissue factor comes into play, as far as I have read, each tissue has different weight factors, and the sum of these factors for the whole body is “1”. I saw on a website (link below) that the tissue weight factor for bone-marrow (red), colon, lung, stomach, breast, remaining tissues is a value like “0.72”. https://ec.europa.eu/health/scientific_committees/opinions_layman/security-scanners/en/figtableboxes/tissue-weighting-factors.htm Therefore, I calculated the total effective dose of my child as 0.02×0.72=0.014 mSv. My specific questions are as follows, I would be very happy if you could answer them: 1- Is there a place where I can officially find the exposure index values of Konica Minolta CR device? I heard that there is information on this subject in AAPM TG116, but I couldn’t find it. Here is the link: https://www.aapm.org/pubs/reports/RPT_116.pdf 2- I don’t think it would be right to calculate my child’s effective dose from the absorbed dose on the detector, but considering the thickness of a 6-month-old child, I guess there won’t be a big difference between my child’s absorbed dose and the dose absorbed by the detector, what do you think? 3- I think that the patient’s age should also be taken into account when calculating the effective dose, but I don’t know how to add it to the calculation, and I can’t find any information on the internet about such a parameter being used for CR scans, what do you think? 4- Can the doses corresponding to the exposure index vary according to the calibration of the device? Does “calibration topic” make a big difference? 5- While the average effective dose for “pelvis” is given as 0.7 mSv on a table shown at hps.org website (https://hps.org/hpspublications/articles/dosesfrommedicalradiation.html), I believe that the value I calculated (0.014 mSv) for my 6-month-old child is not possible to be correct, what do you think? If my above calculation is wrong, may I kindly ask you to make corrections on my calculations step by step to make me understand better? Thank you very much for your time in advance. P.S. I don’t have a medical physics or medical education, I’m just an engineer trying to understand what I read and is very worried about my child, so I’m sorry if there are any fundamental mistakes in what I wrote.. Those I have contacted about this topic have always given me general answers based on literature data, but I would like to know the exact effective dose based on the actual numbers from my child’s scan, please help me. Wishing you all a healthy new year. Best regards. READ MORE
0 By aeadmin In Posted September 13, 2024Hello, in 2020 when my daughter was 4 1/2 years old she had an ear infection that would not go away with antibiotics, tubes and other treatments. The doctor presented an option of an “Xray” since no other diagnostic procedures were available to due Covid. He pushed to have us do the adenoidectomy but I chose the but when I got to the imaging center I found out it would be a CT of her temporal bone. I went ahead with it with little information from her doctor/the radiologist on radiation exposure. I called recently to get the dose and they said she received 55.75 mgy and the report shows DLP 420 with a note that says “pediatric reductions used.” On the phone, a radiologist from the facility she went to said “ooh, I usually turn it down” when reading the CTDI mgy which has caused me great distress the past year. My question is, should I be concerned about the amount of radiation for this one time exposure for my daughter and approximately how much MSV is this? READ MORE
0 By aeadmin In Posted July 5, 2024hi, I have two questions. My first question Is by administering contrast when doing a CAT scan does that increase the amount of msv a person will receive or is the msv the same as without contrast and does the amount of radiation absorb by the organs increase ? For example if an abdominal /pelvic CT scan is 12 msv without contrast , using the same machine if contrast was then given would the total still be 12 msv but the amount of radiation absorbed by the organs be higher with the scan done with contrast as opposed to the one done without contrast ? I also wanted to ask when they say a hip x-ray is 0.6 msv does that mean for only one view or is that for two or even three views ? Thank you READ MORE
0 By aeadmin In Posted May 13, 2024How can I find your guidelines for CT radiation limits? I am 60 years old, both my parents with cancer (mom died), and the insurer recommended me to do a hip CT even though the orthopedic doctor clearly wrote MRI in the referral. I understand the insurer’s preference to save money but given my radiation concern, exacerbated by age and family history and the fact that I already had 5 XRay imaging sessions in the past 12 months (three dental and 2 chest views) – I of course prefer to go for the MRI option. I tried to find in your site any official reference (because they said that “according to the AAPM there is zero risk for me”) – but failed. Can you please advise – considering my history, age, and previous xray sessions this year – what would you consider as an exposure to avoid? Is there really a zero risk? Shouldn’t I insist on the MRI – as recommended by the doctor? Basically I see the discrepancy between the clinical doctor and the administrational doctor. And I need to know that they don’t just use your establishment name in order to “disarm” me and save some dollars… Your insights will be highly appreciated. Especially if you would have advised to insist on the MRI (all considered) READ MORE
0 By aeadmin In Posted April 10, 2024Hi I am not sure if my question went through was I was resubmitting . I have 2 questions . First is it safe to do a full T3 MRI if the spine including lumbar and the a few hours later in the same day do an abdominal pelvic CT ? Does that increase cancer risk ? Second i know they say that MRIs are safe but if they use the sane RF as cell phones then why do they say cell phones cause cancer ? Can MRIs cause cancer like the cell phones can possibly do ? If that is a possibility then could it be dangerous to do an MRI before a CT scan ? Could the heating up of the tissue prior to x rays with the CT lead to more DNA damage ? Thank you , Lisa READ MORE
0 By aeadmin In Posted February 20, 2024When talking about the risks of radiation in X-rays, often it is compared to background radiation. However, scans are usually aimed at a concentrated area of the body in very short amount of time, whereas I assume background radiation is spread across the whole body. Can the two be compared when we talk about risk to individual organs? Does 1 mSv aimed at one part of the body does more damage to that part than 1 mSv worth of background radiation? READ MORE
0 By aeadmin In Posted October 30, 2023My 6 week old baby just had a skull X-Ray that consisted of 5 X-Ray images. Her radiation dose was estimated to be 0.4 mSv. I have been worried about her exposure to this radiation and was wondering if you could help me understand what risk this puts her at for future complications or cancer being that her age is so young? Thank you so much for your help. READ MORE
0 By aeadmin In Posted October 16, 2023My name is Mannah Kaniini, an MSc. student at the University of Zambia, in Zambia. Im doing a research as a requirement for me to graduate. the field of the project i inted to do is in the medical physics field. I have been reading a lot of your publications which i have found quite useful so far. I do have a question on the dosimetric indices such as DHI,COIN,CI,CN,OI, etc. what could be acceptable value for each? from most studies i have seen so far they just generally state the fact that for the CI,COIN and other a value close to 1 is ideal while for DNR and OI 0 is ideal. Is there a threshold or range to accept these values especially for a cervical implant READ MORE
0 By aeadmin In Posted August 16, 2023Hello there, I’m employed at Big Sky Medical Center situated in Big Sky, Montana. My current quest involves obtaining a CT Dose chart that outlines the DLP and CTDI ranges for the average patient dimensions across various body regions. My intention is to display this chart in our CT Tech section for their reference. Interestingly, the ACR didn’t have precisely what I needed and actually suggested reaching out to you. I greatly appreciate your time and assistance. Regards, Mike READ MORE
