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A Small-Scale Anatomic Model for Testicular Radiation Dosimetry for Radionuclides Localized in the Human Testes.

Larsson, Erik LU ; Meerkhan, Suaad LU ; Strand, Sven-Erik LU and Jönsson, Bo-Anders LU (2012) In Journal of Nuclear Medicine 53. p.72-81
Abstract
The testis is a radiosensitive tissue. It contains a large number of lobules, which in turn are composed of convoluted seminiferous tubules. The epithelium inside each tubule consists of a complex mosaic of supporting cells and germ cells of different sizes and degrees of maturation. These cells are known to have diverse sensitivity to radiation, those with the highest sensitivity being the spermatogonia, which form part of the basal cell layer, and those with the lowest sensitivity being the mature sperm cells closest to the lumen of the tubule. For many years, the internal dosimetry community has discussed the need for improvements to bring about more detailed, cell-level testicular dosimetry. This paper presents a small-scale dosimetry... (More)
The testis is a radiosensitive tissue. It contains a large number of lobules, which in turn are composed of convoluted seminiferous tubules. The epithelium inside each tubule consists of a complex mosaic of supporting cells and germ cells of different sizes and degrees of maturation. These cells are known to have diverse sensitivity to radiation, those with the highest sensitivity being the spermatogonia, which form part of the basal cell layer, and those with the lowest sensitivity being the mature sperm cells closest to the lumen of the tubule. For many years, the internal dosimetry community has discussed the need for improvements to bring about more detailed, cell-level testicular dosimetry. This paper presents a small-scale dosimetry model for calculation of S factors for several different source-target configurations within the testicular tissue. METHODS: A model of the testis was designed in which the lobules were approximated by a cross-section of seminiferous tubules arranged in a hexagonal pattern, with interstitial tissue between them. The seminiferous tubules were divided into concentric layers representing spermatogenic development in the seminiferous epithelium. S factors were calculated for electrons, photons, α-particles, and for (18)F, (90)Y, (99m)Tc, (111)In, (125)I, (131)I, (177)Lu, and (211)At using Monte Carlo simulations. RESULTS: For electrons with low energies the range was small, compared with the diameter of the seminiferous tubules, resulting in high energy deposition close to the source, whereas for higher electron energies more uniform energy deposition was seen, as expected. The same trend was seen for low-energy photons, whose mean free paths are small, compared with the diameter of the seminiferous tubules, resulting in high energy deposition close to the source, whereas for higher photon energies the location of the activity in the testis is less important. CONCLUSION: The model presented in this paper is a simplification of the organized chaos that constitutes the structure of the actual testis. However, it provides a relevant, small-scale anatomic model to help us understand the significance of the heterogeneity of radioactivity in this important radiosensitive tissue. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Nuclear Medicine
volume
53
pages
72 - 81
publisher
Society of Nuclear Medicine
external identifiers
  • WOS:000298660900022
  • PMID:22080442
  • Scopus:84855383677
ISSN
0161-5505
DOI
10.2967/jnumed.111.095133
language
English
LU publication?
yes
id
b86231f8-8f19-4797-abef-f5ffd5dbeb13 (old id 2220800)
alternative location
http://www.ncbi.nlm.nih.gov/pubmed/22080442?dopt=Abstract
date added to LUP
2011-12-02 21:26:27
date last changed
2016-10-31 07:43:07
@misc{b86231f8-8f19-4797-abef-f5ffd5dbeb13,
  abstract     = {The testis is a radiosensitive tissue. It contains a large number of lobules, which in turn are composed of convoluted seminiferous tubules. The epithelium inside each tubule consists of a complex mosaic of supporting cells and germ cells of different sizes and degrees of maturation. These cells are known to have diverse sensitivity to radiation, those with the highest sensitivity being the spermatogonia, which form part of the basal cell layer, and those with the lowest sensitivity being the mature sperm cells closest to the lumen of the tubule. For many years, the internal dosimetry community has discussed the need for improvements to bring about more detailed, cell-level testicular dosimetry. This paper presents a small-scale dosimetry model for calculation of S factors for several different source-target configurations within the testicular tissue. METHODS: A model of the testis was designed in which the lobules were approximated by a cross-section of seminiferous tubules arranged in a hexagonal pattern, with interstitial tissue between them. The seminiferous tubules were divided into concentric layers representing spermatogenic development in the seminiferous epithelium. S factors were calculated for electrons, photons, α-particles, and for (18)F, (90)Y, (99m)Tc, (111)In, (125)I, (131)I, (177)Lu, and (211)At using Monte Carlo simulations. RESULTS: For electrons with low energies the range was small, compared with the diameter of the seminiferous tubules, resulting in high energy deposition close to the source, whereas for higher electron energies more uniform energy deposition was seen, as expected. The same trend was seen for low-energy photons, whose mean free paths are small, compared with the diameter of the seminiferous tubules, resulting in high energy deposition close to the source, whereas for higher photon energies the location of the activity in the testis is less important. CONCLUSION: The model presented in this paper is a simplification of the organized chaos that constitutes the structure of the actual testis. However, it provides a relevant, small-scale anatomic model to help us understand the significance of the heterogeneity of radioactivity in this important radiosensitive tissue.},
  author       = {Larsson, Erik and Meerkhan, Suaad and Strand, Sven-Erik and Jönsson, Bo-Anders},
  issn         = {0161-5505},
  language     = {eng},
  pages        = {72--81},
  publisher    = {ARRAY(0x8aa4080)},
  series       = {Journal of Nuclear Medicine},
  title        = {A Small-Scale Anatomic Model for Testicular Radiation Dosimetry for Radionuclides Localized in the Human Testes.},
  url          = {http://dx.doi.org/10.2967/jnumed.111.095133},
  volume       = {53},
  year         = {2012},
}