Absorbed Fraction Sensitivity to Changes in Size of the Icrp Nose Model

Moussa, Hanna; Kf, Eckerman; Lw, Townsend

doi:10.1097/00004032-200203000-00012

Health Physics

2002

DOI: 10.1097/00004032-200203000-00012

|View full text |Cite

Absorbed Fraction Sensitivity to Changes in Size of the Icrp Nose Model

Hanna Moussa

Eckerman Kf²,

Townsend Lw³

Abstract: The Human Respiratory Tract Model of ICRP Publication 66 is used for calculations of dose in the extrathorathic (ET1) airways. Scaling for age and body size is included in determining the mass of the target tissue (basal cells) in ET1 but is not included in deriving the absorbed fraction for particulate radiation. For dose calculations, it has been assumed that all absorbed fractions for particulate radiation published in ICRP Publication 66 are independent of age and body size. Therefore, these absorbed fract… Show more

Help me understand this report

Search citation statements

Order By: Relevance

Paper Sections

Select...

Citation Types

Supporting

Mentioning

Contrasting

Year Published

2004

2006

Publication Types

Select...

Article3

Relationship

Self Cite0

Independent3

Authors

Journals

Cited by 3 publications

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

Charged particle equilibrium effects on the electron absorbed fraction in the extrathoracic airways

Moussa¹,

Eckerman²,

Townsend³

2006

Radiation Protection Dosimetry

View full text Add to dashboard Cite

Estimates of the dose to the extrathoracic airway (nasal vestibule) from inhaled beta-emitting radionuclides, obtained using the respiratory tract model presented in Publication 66 of the International Commission on Radiological Protection, frequently predict that the basal cells in this region are the most highly irradiated tissues of the body. The dose to the basal cells is averaged over a layer of tissue 10 microm thick located at a depth of 40 microm into the airway assuming that charged particle equilibrium exists. Since the target (basal cell layer) is very small and thin (10 cm(2) area and 10 microm thickness), charged particle equilibrium does not exist. In this work the effect on the absorbed fraction of the lack of charged particle equilibrium is investigated.

show abstract

Charged particle equilibrium effects on the electron absorbed fraction in the extrathoracic airways

Moussa¹,

Eckerman²,

Townsend³

2006

Radiation Protection Dosimetry

View full text Add to dashboard Cite

show abstract

Electron Absorbed Fractions Based on a New Model of the Anterior Nasal Passage

Moussa

Kf²,

Lw³

2004

Health Physics

View full text Add to dashboard Cite

In a previous work we reported that the fraction of the electron energy absorbed in the basal cell layer of the anterior nasal passages was not very sensitive to changes in the surface area or radius of the cylindrical model adopted in Publication 66 of the International Commission on Radiological Protection. These absorbed fraction data are used in calculation of the dose to a 10-microm-thick basal cell layer located at a depth of 40 microm in the epithelial cell layer of the extrathoracic (ET1) region. However, these data may only be applicable to the assumed cylindrical geometry and may not be valid for more realistic ET1 geometries. The nose differs in size and shape from one person to another, its shape is not cylindrical but closer to a truncated elliptical cone, and in most humans the nostrils are elliptical in shape. We propose herein a more realistic geometry model, the frustum of a cone, for the anterior nose region (ET1) as an alternative to the cylinder model provided in ICRP 66. The results of absorbed fraction calculations using MCNP4B with the new model are reported. These absorbed fractions are compared to the values previously obtained using the MCNP4B code and a cylindrical model (10 cm2 surface area). We also investigate the effects of changing the size of the truncated cone to represent variations due to sex and age.

show abstract

A Revised Stylized Model of the Adult Extrathoracic and Thoracic Airways for Use With the Icrp-66 Human Respiratory Tract Model

et al. 2004

View full text Add to dashboard Cite

The extrathoracic airways and lymph nodes have not yet been represented explicitly in mathematical or stylized models of the human body utilized in the transport of photons internally between source and target organs. Currently, the ICRP assumes that the extrathoracic airways are reasonably approximated by using the thyroid or brain as the surrogate source and target region within the ICRP 66 respiratory tract model. In the present study, a new mathematical model was created to explicitly consider the extrathoracic airways, as well as other respiratory structures in the thorax of the adult. The model incorporates the MIRD model of the adult head and neck, and the ORNL model of the adult torso/legs. Additional defining equations are established for the external nose, nasal cavity, nasal sinuses (frontal, ethmoid, sphenoid, and maxillary sinuses), oral cavity, larynx, pharynx, trachea, and main bronchi. Use of the thyroid as a surrogate source for photon emissions in the ET1 and ET2 tissues is shown to provide either close or conservative values of specific absorbed fraction to target organs such as the lungs or breasts at energies exceeding 50-100 keV. At lower energies, surrogate-region values of SAF underestimate dose to target organs in ways highly dependent upon the source/target configuration. The use of the brain as a surrogate source for ET1 and ET2 tissues irradiating the thyroid is shown to result in SAF values that are lower than values of SAF(thyroid<--ET1) by factors of approximately 2-3, and lower than values of SAF(thyroid<--ET2) by factors of approximately 30 at photon energies >50 keV. At energies <50 keV, values of SAF(thyroid<--ET2) are shown to be orders of magnitude higher than the ICRP 66 default given by SAF(thyroid<--brain).

show abstract

scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.

Contact Info

customersupport@researchsolutions.com

10624 S. Eastern Ave., Ste. A-614

Henderson, NV 89052, USA

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.

Blog Terms and Conditions API Terms Privacy Policy Contact Cookie Preferences Do Not Sell or Share My Personal Information

Made with 💙 for researchers

Part of the Research Solutions Family.

Absorbed Fraction Sensitivity to Changes in Size of the Icrp Nose Model

Cited by 3 publications

References 1 publication

Charged particle equilibrium effects on the electron absorbed fraction in the extrathoracic airways

Charged particle equilibrium effects on the electron absorbed fraction in the extrathoracic airways

Electron Absorbed Fractions Based on a New Model of the Anterior Nasal Passage

A Revised Stylized Model of the Adult Extrathoracic and Thoracic Airways for Use With the Icrp-66 Human Respiratory Tract Model

Contact Info

Product

Resources

About