Hi all,
I have a question about understanding the dosage of CT my radiologist gave.
On 12/2013, I accidentally found a .7 mm nodule in my left lung. and I did another follow up CT on 07/2014, and then 01/2015. I was reassured that all of these CT are low dose CT scan given that I am in the low risk profile.
However, contrast to what I thought they are low dose Chest CT (typically 1.5 mSv), below is the info I found in previous 3 CT scans:
CT date. 12.2013: DLP=569mGycm which calculates to about 9.6 mSv
CT date. 7.2014: DLP=462 mGycm which corresponds to 7.8 mSv
CT date. 1.2015: DLP=171 mGycm which corresponds to 2.9 mSv
the formula I used to calculate: E=DLP * k (0.017)
The first CT scan is even higher than standard Chest CT scan dosage (~7mSv), and second CT scan is still higher than standard. the CTDIvol of 1st and 2nd CT scan are 14 ~ 15 mGy. While I consult with my pulmonologist, he cannot provide the answer on why the previous 2 CT are not strictly low for low dose CT scan.
I hope I have misread them, and they are actually a reasonable dosage for CT scan, as my faith is the hospital I was going is a top hospital for early lung detection.
Are the above dosage presented normal? Using a higher dosage and gradually reduce, but claiming as LDCT, is it normal?
Can anyone from radiologist background help me to interpret this? As I will have another follow up, if this is an issue and not fixed, there will be more radiation than it is necessary.
If height and weight is an issue, I am ~160 lbs and 5'7''. LDCT Chest. Young age and low risk profile group.
Thank you all.
Marcus
Reply # - February 12, 2015, 09:16 PM
Hi Marcus,
Hi Marcus,
The first two scans were in the normal range of a standard chest CT rather than a low-dose scan. You would need to discuss with the radiology department of the hospital where the scans were performed. Dr. Manning wrote a post on radiation exposure from CT scans which you can find here. And there was a discussion of the risks from CT radiation (prompted by a rather dubious study) here.
JimC
Forum moderator
Reply # - February 13, 2015, 07:29 AM
Jim,
Jim,
Thank you, for your prompted reply.
As the first CT was in 2013, I don't know if they still able to understand why then was ordering an standard CT instead. But I will reach out to them.
One more follow up question on this - For first time scanning in CT after Xray found suspicious, would it usually be a standard CT, for the sake of clear image? Or a low dose CT would usually be performed for low risk profile patient? After the first scan, I was transferred to SCCA, so the second scan was technically the first scan of second hospital.
Thank you sincerely,
Marcus
Reply # - February 13, 2015, 07:47 AM
Marcus,
Marcus,
I think if something was seen on an x-ray, there would be a preference for a standard CT for the reason you state - to get the best possible image. Even though other factors might make you low-risk, the finding on the x-ray would raise enough concern to warrant a high-resolution scan.
JimC
Forum moderator