Dear ICRP committee members,
In general, the author wishes to express his approval at the writing of the first ICRP Assessment of Radiation Exposure of Astronauts in Space. This is a very informative and timely document which will prove very useful in a field where, unfortunately, concepts and terminology may be quite ambiguous. In addition to the comments which have already been made, the author wishes to comment on the following lines:
489-490 It is confusing to be referring to effective dose and equivalent dose in this manner, because these quantities are no longer recommended for space applications. Recommend inserting “for terrestrial applications”.
848-849 Graph y-axis values to be changed.
891 Elsewhere (Durante and Cucinotta 2011, etc.) Figure 2.2 has the reference
F. A. Cucinotta, H. Wu, M. R. Shavers, and K. George. Radiation dosimetry and biophysical models of space radiation effects. Gravitational and Space Biology, 16(2):11-18, 2003.
901-902 Is this figure with the newest data? This 2003 graph leads to apparent inconsistencies with newer NASA data (from Table 2.7 on page 30 of NASA/TP-2011-216155).
1043-1044 Many figures have incorrect legends.
1334 Effective dose equivalent is also a protection quantity, in fact the recommended one for space, and so should be defined here. Ideally, it should be contrasted with effective dose, clarifying the difference. It would perhaps also be helpful to contrast here dose equivalent and equivalent dose.
1402-1404 The previous comment, defining the alternative effective dose equivalent, would help to clarify this obscure point.
1415 Confusing to have dose equivalent here only, in the “Operational quantities” section, as it is clearly stated on line 156 that no operational quantity is recommended for space. By recommending the use of the Q(L) function, the ICRP is effectively sanctioning the use of dose equivalent, which has been defined only as an “Operational quantity”.
1432 The terms “expanded” and “aligned” are not to be found in the Glossary.
1488 Should specify the time period, as deterministic effects’ limits are over a time period. If a lifetime value, this should be stated.
1514 Editorial: increase
1729 AP incidence should be in the Glossary as Anterior-Posterior.
1980 See comment on line 1488. If time is uncertain, “on the order of days”, or similar vague wording would be helpful.
3016 Citation would be appropriate here.
3017-3018 Citation and argument would be appropriate for this very strong statement.
3055 This section should be changed to be consistent with the other codes. The code originates at CERN, and a suite of space applications have been developed by ESA, including GRAS, MULASSIS, SSAT. GRAS should be cited, MULASSIS should have the correct citation.
F. Lei, P.R. Truscott, C.S. Dyer, B. Quaghebeur, D. Heynderickx, P. Nieminen, H. Evans, and E. Daly. MULASSIS: A Geant4-Based Multilayered Shielding Simulation Tool. IEEE Transactions on Nuclear Science, 49: 2788-2793, December 2002.
GRAS and SSAT citation:
G. Santin, P. Nieminen, H. Evans, E. Daly, F. Lei, P.R. Truscott, C.S. Dyer, B. Quaghebeur, and D. Heynderickx. New Geant4 based simulation tools for space radiation shielding and effects analysis. Nuclear Physics B, 125:69-74, September 2003.
3069-3070 Statement gives the impression that much of the Geant4 code is simply copied from HZETRN and others, and should be softened. As correctly stated on lines 3058-3059, Geant4 has been developed and is maintained by a large collaboration for many particle physics applications.
3105 No Wilson 2009 reference exists.
3301-3302 As dose equivalent cannot be related to current agency dose limits, and is not recommended for use by the present report, it is an odd choice of quantity to be plotting, considering the wealth of alternatives. Figures 5.9 and 5.10 should be in terms of effective dose equivalent, the recommended quantity for space applications, which changes the shape of the plots significantly. The use of dose equivalent here also promotes uncertainty as to the recommended quantity. Excellent NASA figures are available in NASA TM-2012-217361, NASA/TP-2011-216155, or
Martha S. Clowdsley, John W. Wilson, Myung-hee Kim, Brooke M. Anderson, and John E. Nealy. Radiation protection quantities for near earth environments. In AIAA Space 2004 Conference and Exposition, 2004.
3312 This statement cannot be fully verified from Figure 5.9, as the correct approximation to whole-body dose – effective dose equivalent – is not used.
3328 As in previous point, figures with dose equivalent on the y-axis are misleading in several ways and should be avoided – they cause confusion as to the recommended quantity, and incorrect conclusions about effects of shielding on a complete phantom could be drawn.
3350 Paragraph (259). These statements are true and helpful for trapped radiation and SPEs, but not necessarily for GCRs. Due to the flatness of dose – depth and effective dose equivalent curves for GCRs, very little geometrical information can be seen. This point would be obvious if figures 5.9 and 5.10 a) were in the appropriate units.
3363 The words “effective dose” should be replaced with “effective dose equivalent”, also in several other places in the text. Great care should be taken to avoid interchanging these terms, especially in this ICRP report. It is highly recommended that the use of the term “effective dose” be reviewed throughout the document, as its association with dose equivalent vs. equivalent dose remains confusing.
3363 A citation is also required here.
3570 Editorial: the space environment
3571 Paragraph 278 should be reworded for grammar. Also, to my knowledge ESA has not adopted these coefficients before a month ago. The statement “Most space organizations” should then be replaced by “NASA”. Do you have any evidence that ESA has been using fluence-to-dose equivalent coefficients since the late 1990s?
3394 It is suggested that it would be extremely helpful to include dose limits of the major space agencies in this section, when publicly available, in their correct units and quantities. Both short- and long-term limits should be included. This information is unfortunately difficult to come by and often presented ambiguously, incompletely, or using out-of-date values or units. As this is the first ICRP report of its kind, precedent has not yet been set as to their presence, and these dose limits are critical for most calculations or measurements. Their inclusion would thus be highly appropriate; in fact the absence of these critical values would be a grave omission.