Radiological Protection in PET and PET/CT

Draft document: Radiological Protection in PET and PET/CT
Submitted by Kwan Hoong Ng, AsiaSafe - From Japan
Commenting on behalf of the organisation

October 8, 2023

Comments on TG117 Draft Document: Radiological Protection in PET and PET/CT
Japan Radiological Society,

Line 2702:
"the CT effective doses were 8.0, 10.4, and 11.9 mSv for head and neck, torso, and whole-
body protocols, with mean scanned patient length of 761, 839, and 926 mm, respectively
(Martí-Climent et al ., 2017)."
In this paper (Martí-Climent et al ., 2017), for "head and neck tumors", the "head and neck"
and "trunk" are imaged separately. And 8.0 mSv is the dose of "trunk" while 1.7 mSv is that
of "head and neck". This should be corrected.
Line 2625, a low tube current (30-50 mAs):
The unit of tube current is mA, and the unit of mAs is tube current-time product or effective
tube current-time product.
There is a similar point with line 4402.
In Table 6.3, mAs is used as the name of an index rather than a unit, and I am concerned
whether the same word can be used in two ways in one manuscript. I know it may often
appear in papers. Please kindly reconsider whether it can be left as it is.
Line 4411:
"GE uses noise index to determine image quality by adjusting the peak kilovoltage and
minimum or maximum tube current"
However, as you know, GE's CT equipment mainly uses noise index to define image quality
and adjust tube current to achieve the specified image quality, but tube current has upper
and lower limits.
Thus it may be rewritten while respecting the original as follows.
"GE uses noise index, supplemented by minimum and maximum tube currents, to
determine image quality by adjusting tube current".
It would be good to mention that the variations among facilities in the medical exposure that
patients receive on PET/CT are larger with CT doses than with radiotracer doses.
When nuclear medicine technologists and medical physicists were listed side by side, x-ray
technologists could also be listed as staff members.

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