The ICRP Computational Framework for Internal Dose Assessment for Reference Workers: Specific Absorbed Fractions

Draft document: The ICRP Computational Framework for Internal Dose Assessment for Reference Workers: Specific Absorbed Fractions
Submitted by Jan Jansen, Centre for Radiation, Chemical and Environmental Hazards
Commenting as an individual

AdultSAFDraftForPublicConsultation.pdf comments.

I would like to make some comments on that part of the document I am more familiar with.

Page number is according to the PDF and line numbers according to the left most columns. The line numbers alone should already give a unique number because they are continuous counting, but the page numbers are supplied for convenience. I am only commenting on a small part of report that is the most relevant to my work.


Page   Line          Comment

18        513            Should Ãi(rs) (Bq s) not be Ãi(rs,τ) [Bq s]? The units are given within square brackets on page 19 line 534. This applies for the whole document, like line 518 where (s) should be [s]. Formula (2.2) defines Ãi(rs,τ) and not Ãi(rs).

18        529            Should the integration time symbol not be τ instead of t?

18-9    531            Formula (2.4) and (2.5) define the new symbols h[F|M](rT, τ) with the new symbols S[F|M]W(rT <- rS)I and without a forward reference to formula (2.9) that defines S coefficients. This might be considered as not elegant.

19        544-546   “With the exception of the tissues addressed in Table 3, the tissues of Table 2 are represented by a single target region and thus for these tissues f(rT,T) = 1.” Not according to ICRP Publication 110 Annex D with the list of target regions. The target regions active marrow, breast, ovaries, testes, … all have more than one ID number.

19        554            Table 3 defines the target region Lymphatic nodes WITH the ET and TH regions, where ICRP Publication 110 explicitly excludes them in Annex D Table D.1 on page 69.

20        559            The committed effective dose coefficient, e(τ), has the unit [Sv s] and it might be helpful to add for all the symbols defined in this document the units.

20        560            Analogy: Activity A, Committed activity Ã, Committed activity coefficient ã, so effective dose E, Committed effective dose ~E (~ should be above E), Committed effective dose coefficient ~e (~ should be above e). Why did the Commission choose for committed effective dose coefficient the symbol e without the ~ on top?

20        567            Line 539 has as unit part (Bq s) and there the same unit part is denoted (Bq-s). Please use one notation throughout the document.

20        571-578   All the symbol units, if any, are supplied, except for ER.i where the [MeV] or [J] is missing. Why?

20        582            Equation 9 should be equation 2.9?

21        600            The symbol SAF(rT <- rS) is used with SAF above, although on page 20 line 567 the symbol Φ is used when SAF is introduced. Please use one symbol SAF or  Φ throughout the document.

21        600            The reader has to guess that MrS is the mass [kg] of source region, S, and that MOtherrS MrS . The text would improve if this information was supplied. In addition, introduce all used symbols in the glossary with their units.

22        626            Is the word cuboid right? Or is rectangular cuboid better?

24        677            MIRD Pamphlet No. 5 (1978) is published after No. 11 (1975)?

24        685            Typo with self-irraidation for self-irradiation.

24        688-691   The sentence “Since the difference … while allowing for an improved SAF at low photon energies.” does imply two things. 1) The difference in organ mass between ICRP Publication 89 and 110 are small so the reference target mass can be used, whatever the photon energies are. 2) The SAF proportionality with the inverse cube root of the squared target mass (Snyder 1970) is approximated as proportional to the inverse target mass and this improves the SAF at low photon energies. For muscle (skeletal) (soft tissue) the Compton effect is dominating for and above 30 keV photon energy, so indeed low photon energies, up to about 30 MeV, where pair production start to be the dominant effect. On the higher end the photon energy is beyond the 10 MeV and that is about the maximum in this report and produced by radio-nuclides. The target masses vary with muscle 23 kg on the high end and gall bladder wall 0.010 kg on the low end. For photon energies in the range where the Snyder approximation holds it is assumed that: 1 = M1/3 with for M=23 kg 1 = 2.8 and for M=0.010 kg 1 = 0.21, that are about a factor of 3 to 1/5 differences. Even for radiation protection, these differences are not small. This last part needs additional information or a reference to additional information or further improvement. It is a worst case because only photons with an energy above 30 keV are considered. In practice, it might be a reasonable approximation but this needs additional text or a reference to this additional text.