Preface, Executive Summary and Glossary

This report provides a summary of the methods and procedures used to create the computational phantoms corresponding to the adult Reference Male and Reference Female from individual-specific tomographic data. The methods and procedures used in this activity have been reported in numerous publications. These phantoms are designed specifically for calculation of the radiological protection quantities corresponding to the effective dose concept of the 2007 Recommendations of the Commission. The phantoms are presented to the radiation protection community in numerical format, with identification of source and target regions of the body in the CD inserted at the back cover of this publication. Due to the numerical nature of the phantoms and earlier publication of the characteristics of the adult Reference Male and Reference Female, this document was not provided for public consultation. The authors acknowledge the comments received from the ICRP Committees, the International Commission on Radiation Units and Measurements (ICRU), and selected expert reviewers.

Although being released as an ICRP publication, the present report is a joint publication of ICRP and ICRU.

This report was compiled by a Subgroup of the Task Group on Dose Calculations of ICRP Committee 2. The membership was as follows:

	M. Zankl (Chairperson)	K.F. Eckerman	N. Petoussi-Henss
	W.E. Bolch	H.G. Menzel

The membership of the Task Group on Dose Calculations of ICRP Committee 2 during the preparation of this report was:

	2001–2005 (full members)
	K.F. Eckerman (Chairman)	W.E. Bolch	A. Phipps
	H.G. Menzel (Vice-Chair, External Dosimetry)	N. Hertel	B.R.L. Siebert
	D. Nosske (Vice-Chair, Internal Dosimetry)	N. Petoussi-Henss	M. Zankl
	V. Berkovski

	2001–2005 (corresponding members)
	L. Bertelli	G.M. Kendall	A.R. Reddy
	A. Endo	R. Leggett	R. Richardson
	T. Fell	I. Likhtarev	M.G. Stabin
	J. Hunt	G. Miller	A. Ulanovsky
	L. Johansson	M. Pelliccioni	X.G. Xu

	2005–2009 (full members)
	W.E. Bolch (Chairman, 2007–2009)	E. Blanchardon	M. Pelliccioni
	K.F. Eckerman (Chairman, 2005–2007)	A. Endo	A. Phipps (2005–2007)
	D. Nosske (Vice-Chair, Internal Dosimetry)	N. Hertel	M. Zankl
	N. Petoussi-Henss (Vice-Chair, External Dosimetry)	J. Hunt
	V. Berkovski	H.G. Menzel (2005–2007)

	2005–2009 (corresponding members)
	L. Bertelli	R. Richardson	A. Ulanovsky
	T. Fell	M.G. Stabin	X.G. Xu

The membership of ICRP Committee 2 during the preparation of this report was:

	2001–2005
	C. Streffer (Chairman)	F.A. Fry	H.G. Paretzke
	M. Balonov	J. Inaba	A.S. Pradhan
	B.B. Boecker	I.A. Likhtarev	J.W. Stather (Vice-Chairman)
	A. Bouville	J.L. Lipsztein	D. Taylor (Secretary)
	G. Dietze	H.G. Menzel	Y.Z. Zhou
	K.F. Eckerman	H. Métivier

	2005–2009
	H.G. Menzel (Chairman, 2007–2009)	G. Dietze	H.G. Paretzke
	C. Streffer (Chairman, 2005–2007)	K.F. Eckerman	F. Paquet
	M. Balonov	J.D. Harrison (Secretary)	A.S. Pradhan
	V. Berkovski	N. Ishigure	J.W. Stather
			(2005–2007)
	W.E. Bolch	P. Jacob (2007–2009)	Y.Z. Zhou
	A. Bouville	J.L. Lipsztein

The ICRU sponsors of the report were:

	H.G. Menzel	H.G. Paretzke

Members of ICRU during the preparation of this report were:

	P.M. DeLuca (Chairman)	D.T.L. Jones	H. Tatsuzaki
	P. Dawson	H.G. Menzel	A. Wambersie
	K. Doi	B.D. Michael	G.F. Whitmore
	R.A. Gahbauer	H.G. Paretzke
	M. Inokuti	S.M. Seltzer

MAIN POINTS 

•The phantoms presented in this document are the official computational models representing the Reference Male and Reference Female (ICRP, 2002, ICRP, 2007). These reference computational models are based on computed tomographic data of real people and, hence, are digital three-dimensional representations of human anatomy.

•For the construction of the reference computational models, tomographic data sets were selected of individuals with external dimensions close to the reference data. From these data, voxel phantoms were segmented and then adjusted to the reference values given in Publication 89 (ICRP, 2002).

•Most relevant source and target regions are adjusted to their reference mass values with high precision. Exceptions and limitations are discussed.

•The phantoms’ technical descriptions are contained in a series of annexes that form the larger part of this report.

•The numerical data representing the phantoms are contained on an electronic data storage medium (CD-ROM) that accompanies the printed document. One of the aims of this report is to assist those who wish to implement the phantoms for their own calculations.

(a) This report describes the development and intended use of the computational phantoms of the Reference Male and Reference Female. In its 2007 Recommendations, ICRP adopted these computational phantoms for the forthcoming update of organ dose coefficients for internal and external radiation sources (ICRP, 2007). The phantoms are based on medical image data of real people and are consistent with the information given in Publication 89 (ICRP, 2002) on the reference anatomical and physiological parameters for both male and female subjects. The reference voxel models were constructed after modifying the voxel models (Golem and Laura) of two individuals whose body height and mass closely resembled the reference data. The organ masses of both models were adjusted to the ICRP data on the adult Reference Male and Reference Female, without significantly altering their realistic anatomy. The report describes the methods used for this process and the characteristics of the resulting voxel phantoms. Furthermore, to illustrate the uses of these phantoms, conversion coefficients for some external and internal exposures are also included.

(b) The numerical data representing the phantoms are contained on an electronic data storage medium (CD-ROM) that accompanies the printed publication. One of the aims of this report is to assist those who wish to implement the phantoms for their own calculations.

(c) Chapter 1 summarises the main reasons for constructing these phantoms – voxel phantoms being the state of the art, and the necessity for compliance with the anatomical characteristics of the Reference Male and Reference Female given in Publication 89 (ICRP, 2002). Chapter 2 summarises the specifications of the computational phantoms with respect to external dimensions and the source and target regions that are required. Chapter 3 characterises the previously segmented voxel models (Golem and Laura) that are the origins of the reference phantoms. Chapter 4 sketches the modifications that had to be applied to these models to create voxel models of the Reference Male and Reference Female. Chapter 5 is a description of the resulting reference computational phantoms of the Reference Male and Reference Female. Finally, Chapter 6 indicates their applications and highlights their limitations.

(d) The phantoms’ technical descriptions are contained in a series of annexes that form the larger part of this publication.

(e) Annex A presents a list of the individually segmented organs/structures (identification list), together with the assigned media, densities, masses, containing boxes, and centres of mass.

(f) Annex B presents a list of the phantom media and their elemental compositions.

(g) Annex C is a list of the source regions, together with their typically used acronyms and the identification numbers that make up these source regions, and Annex D presents the respective data for the target regions.

(h) In Annex E, distributions are given of the thickness of tissue shielding selected organs from the front, back, left, right, top, and bottom; these distributions are presented in graphical form.

(i) In Annex F, chord-length distributions between selected pairs of source and target organs are presented in graphical form.

(j) Annex G presents selected transverse, sagittal, and coronal slice images of both reference computational phantoms.

(k) Furthermore, to illustrate the uses of these phantoms, graphical illustrations of conversion coefficients for some external and internal exposures are included in Annexes H–L. A comprehensive set of recommended values will be published in separate reports.

(l) In Annex H, some selected organ dose conversion coefficients for external exposure to monoenergetic photons are presented.

(m) Annex I presents some selected organ dose conversion coefficients for external exposure to monoenergetic neutrons.

(n) In Annex J, some selected organ dose conversion coefficients are presented for external exposure to helium ions.

(o) In Annexes K and L, specific absorbed fractions are given for selected source and target region pairs for monoenergetic photons and electrons, respectively.

(p) Annex M summarises the contents of the CD-ROM containing the phantom numerical data.

Absorbed dose, D

The fundamental dose quantity given by:

Active (bone) marrow

Active marrow is haematopoietically active and gets its red colour from the large numbers of erythrocytes (red blood cells) being produced. Active bone marrow serves as a target tissue for radiogenic risk of leukaemia.

Bone marrow

Bone marrow is a soft, highly cellular tissue that occupies the cylindrical cavities of long bones and the cavities within the trabecular bone of the vertebrae, ribs, sternum, and the flat bones of the cranium and pelvis. Total bone marrow consists of a sponge-like, reticular, connective tissue framework called ‘stroma’, myeloid (blood-cell-forming) tissue, fat cells, small accumulations of lymphatic tissue, and numerous blood vessels and sinusoids. There are two types of bone marrow: active (red) and inactive (yellow). See ‘Active (bone) marrow’ and ‘Inactive (bone) marrow’.

Cortical (bone) marrow

The marrow contained in the medullary cavities in the shafts of the long bones.

Dose coefficient

Used as a generic term for coefficients relating a dose quantity to another physical quantity, both for internal and external radiation exposure. In internal dosimetry, a typical dose coefficient is the dose per unit intake of a radioactive substance; in external dosimetry, these are dose conversion coefficients.

Dose equivalent, H

The product of D and Q at a point in tissue, where D is the absorbed dose and Q is the quality factor for the specific radiation at this point, thus:

The unit of dose equivalent is joule per kilogramme (J/kg), and its special name is sievert (Sv).

Effective dose, E

The tissue-weighted sum of the equivalent doses in all specified tissues and organs of the body, given by the expression:

where HT or wR DT,R is the equivalent dose in a tissue or organ, T, and wT is the tissue weighting factor. The unit for the effective dose is the same as for absorbed dose (J/kg), and its special name is sievert (Sv).

Endosteum (or endosteal tissue)

A 50-μm-thick layer covering the surfaces of the bone trabeculae in regions of trabecular spongiosa and the cortical surfaces of the medullary cavities of the shafts of all long bones. It serves as the target tissue for radiogenic bone cancer. In contrast to previous assumptions, recent studies have indicated that the cells at risk for bone cancer induction are localised out to 50μm (previously assumed: 10μm) from both the trabecular surfaces and interior cortical surfaces of the medullary cavities, but not within the Haversian canals of cortical bone.

Equivalent dose, HT

The dose in a tissue or organ T given by:

Fluence, Φ

The quotient of dN by da, where dN is the number of particles incident on a sphere of cross-sectional area da, thus:

The use of a sphere of cross-sectional area da is to express the fact that the area da is considered to be perpendicular to the direction of each particle regardless of its spatial orientation.

Identification (ID) number

Number assigned unequivocally to each individually segmented organ/tissue.

Inactive (bone) marrow

In contrast to the active marrow, the inactive marrow is haematopoietically inactive, i.e. does not directly support haematopoiesis. It gets its yellow colour from fat cells, which occupy most of the space of the yellow bone marrow framework.

Marrow cellularity

The fraction of bone marrow volume in a given bone that is haematopoietically active. Age- and bone-site-dependent reference values for marrow cellularity are given in Table 41 of Publication 70 (ICRP, 1995).

Red (bone) marrow

See ‘Active (bone) marrow’.

Reference Male and Reference Female (Reference Individual)

An idealised male or female with characteristics defined by the Commission for the purpose of radiological protection, and with the anatomical and physiological characteristics defined in the report of the ICRP Task Group on Reference Man (ICRP, 2002).

Reference Person

An idealised person for whom the organ or tissue equivalent doses are calculated by averaging the corresponding doses of the Reference Male and Reference Female. The equivalent doses of the Reference Person are used for calculation of the effective dose by multiplying these doses by the corresponding tissue weighting factors.

Reference phantom

Computational phantoms for the human body (male and female voxel phantoms based on medical imaging data) with the anatomical and physiological characteristics defined in the report of the ICRP Task Group on Reference Man (ICRP, 2002).

Reference value

Standardised value of a parameter recommended by the Commission. Examples are the standardised set of anatomical and physiological parameters for radiation protection purposes summarised in Publication 89 (ICRP, 2002).

Response function

Function representing the absorbed dose in a target region per unit particle fluence in the region, derived using models of the microscopic structure of the target region geometry, and the transport of the secondary ionising radiations in those regions.

Source region, Si

An anatomical region within the reference phantom which contains the radionuclide following its intake. The region may be an organ, a tissue, the contents of the gastrointestinal tract or urinary bladder, or the surfaces of tissues in the skeleton, the alimentary tract, or the respiratory tract.

Specific absorbed fraction

The fraction of energy emitted as a specified radiation type in a source region, S, that is absorbed per unit mass of target tissue, T. The unit for the specific absorbed fraction is per kilogram (/kg).

Target region, Ti

Anatomical region within the body (reference phantom) in which radiation is absorbed. The region may be an organ or a specified tissue in the gastrointestinal tract, urinary bladder, skeleton, or respiratory tract.

Tissue weighting factor, wT

The factor by which the equivalent dose in a tissue or organ T is weighted to represent the relative contribution of that tissue or organ to the total health detriment resulting from uniform irradiation of the body (ICRP, 1991). It is weighted such that:

Trabecular (bone) marrow

The marrow contained in the spongiosa regions of all bones.

Voxel phantom

Computational anthropomorphic phantom based on medical tomographic images in which the anatomy is described by small three-dimensional volume elements (voxels) specifying the organ or tissue to which they belong.

Yellow (bone) marrow

See ‘Inactive (bone) marrow’.