Dosimetric quantities

Draft document: Dosimetric quantities
Submitted by Hiroshi Noguchi, Japan Atomic Energy Research Institute, Department of Health Physics
Commenting on behalf of the organisation

General Comment Some contradictions, e.g. gdefinition of collective doseh, are seen between the foundation documents opened by ICRP. ICRP should iron out the differences of description between the documents by each Committee before their publishing. Specific Comments Introduction Page 4, Line14 - 16 The concern of radiological protection is defined as gcontrolling exposures to ionizing radiation so that acute damage is prevented and the risk of long term health effects is limited acceptable levels.h ICRP Publication 60 (in paragraph 100) states gthe Commissionfs basic framework is intended to prevent the occurrence of deterministic effectsc and to ensure that all reasonable steps are taken to reduce the induction of stochastic effectsh. We think that the previous expression (in ICRP Publ. 60) is preferable to state the framework of radiological protection. 2. Health Effects Page 7, Line 31- 32 The description of N (the product of all other modifying factors) in dose equivalent, H, should be moved to the former paragraph below the equation of (2.1). Since gNh had been already abolished in ICRP Publ. 60, gNh should not appear together with radiation weighting factors, wR, and tissue weighting factors, wT, which are related to effective dose, E. Page 8, Line 38 - 41 The foundation document recommends using the unit of Gy to absorbed dose and RBE weighted dose. The process of discussion to this decision should be clarified. 3. Dose Quantities in Radiological Protection Page 18, Line 3 galpha-particlesh in the parentheses should be deleted because the external exposure to alpha-particles does not seem to be problem. Page 15 - Page 20 (Section 3.4 Operational quantities) The expression of operational quantities for external exposure should be agreed with the definition of operational quantities in the ICRU Reports. Otherwise, new interpretation and confusions may be brought in radiological protection for external exposure. 4. Weighting Factors Page 26, Line 41- 42 In addition to neutrons, protons and heavy ions are represented as strongly penetrating external radiation for the equation of (4.1). On the other hand, neutrons and photons are categorized as the strongly penetrating radiation for operational quantities in ICRU reports. Most scientists concerned to radiological protection would support the definition in ICRU reports. Then, the term gstrongly penetrating external radiationh in page 26 line 41 should be replaced with other expressions. Page 33, Line 20-26 The text of gthe wT for reminder (0.12) is divided equally between the 15 specified tissue given in Table 2, i.e., approximately 0.008 eachh should be replaced by gnominal wT is applied to the average dose to 14 tissues for each of male and femaleh. This is because 14 tissues are listed for male and female in Table 2 and the wT is applied to the average of gender-specific dose to the remainder, as given by Equation (5.9). Table 2 should be also changed like this. Page 59, Figure 2 It is desirable to put the number of g1h at the left side of the bottom of vertical axis for readersf convenience, as seen in the similar figure in ICRP Publ. 60. 5. Practical Application in Radiological Protection Page 43, Line 20 - 24 This paragraph expresses the equations of (5.11) to (5.13). Three parameters, gtime periodh, ggeographical regionsh and gdose rangeh, should be taken into account to derive collective dose. While the term of gtime periodh is seen in the two sentences, the term of gdose rangeh is not seen here. Should the sentence of gAlso the time periodch be modified to gAlso the dose rangech? 6. Uncertainties and Judgments in Radiological Protection The following statements are stressed in the last paragraph as a conclusion. /The described reference values for models and parameters should be prospective radiological protection purposes. It is not especially valid to use these models and parameter values for retrospective dose assessments. /This limitation of usage for prospective assessments only must be especially considered with respect to effective doseh. However, doses in past radiation exposure events have been estimated in terms of the effective dose, for example in UNSCEAR or IAEA reports. The conclusion of this document denies these dose assessment already performed. Then, ICRP should make further discussions to extend the application of the dose quantity for radiation protection in this document to other dose assessments. Others (References) We think that the revisions for values of radiation weighting factors are quite important in this foundation document. However, two significant reports; Schmid et al. (2004) on page 27 and Yoshizawa (1998) on page 28 are missing in the list of references.