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Correlation between mean lethal dose and organ weight

Published online by Cambridge University Press:  01 September 2009

Syed F. Akber  and
Than S. Kehwar
Syed F. Akber
Affiliation:
1Department of Radiation Therapy, Case Western Reserve University, Cleveland, Ohio, USA
Than S. Kehwar*
Affiliation:
2Department of Radiation Oncology, University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania, USA
*
Correspondence to: Than S. Kehwar, Department of Radiation Oncology, University of Pittsburgh Cancer Institute, UPMC St. Margaret Hospital, 815 Freeport Road, Pittsburgh, PA 15215, USA. E-mail: drkehwar@gmail.com
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Abstract

The assessment of mean lethal dose (Do) with organ weight in human organs yields a correlation coefficient of 0.94. Results indicate that as the organ weight increases, the Do decreases.

Keywords

Mean lethal doseOrgan weightradiation tolerance

Information

Type
Short Communication
Information
Journal of Radiotherapy in Practice , Volume 8 , Issue 3 , September 2009 , pp. 163 - 164
Copyright
Copyright © Cambridge University Press 2009

INTRODUCTION

With the introduction of three-dimensional treatment planning for dose calculation, it is becoming more apparent that there is an acute need for comprehensive information about the mean lethal radiation dose (Do)/radiation tolerance dose data of normal human tissues. The degree of injury that is considered “lethal” is often measured at the time after irradiation at which lethality is assessed. Different investigators have arrived at different absolute “Dos” and even different relative rankings of Dos. Hence there is considerable disagreement as to its actual value.

MATERIALS AND METHODS

CohenReference Cohen1 has reported Dos (multi-target-model) for few human organs (Table 1). The Dos are calculated from patients of different age, sex and body weight as well as organ weight. CohenReference Cohen2, in his personal communication, had provided the best final values of Dos for the organs such as skin, spine, lung and gut whereas the brain and kidney values are extracted from his published works. However, Cohen1 provided Do values of other organs but unfortunately actual organ weights are not found in the literature.

Table 1.

Mean lethal radiation dose and organ weight of normal human organs

RESULTS

Given these constraints, if one correlates Dos against 70 kg standard man organ weight3 one obtains a correlation coefficient of 0.94 (Figure 1). It is interesting to note from Figure 1 that as the organ increases in size/weight by assembling many cells of different function (tissue organisation) the mean Do decreases. Similarly, AkberReference Akber4 has shown that the radiation tolerance dose (TD50) in human decreases as organ weight increases.

Figure 1.

Correlation between mean lethal radiation dose and organ weight in human organs

DISCUSSION

It appears that the Do/radiation tolerance dose is dependent on organ weight. It is, however, important to realise that many physiologic processes such as heat loss and oxygen diffusion from the blood to the tissue across the capillary walls are indeed functions of the tissue organisation. The overall metabolism, therefore, cannot be independent of tissue organisation–organ weight. However, it would be worthwhile to investigate this concept from autopsied human beings of organ weight. Animal models would also be very helpful in providing an insight to the present approach.

References

Cohen, L. Biophysical Models in Radiation Oncology. Boca Raton, Florida: CRC-Press, 1983.Google Scholar
Cohen, L. The best final values of mean lethal radiation doses for skin, spine, lung and gut. Personal communication, 1997.Google Scholar
ICRP report no. 23. 1975. Report of the Task Group on Reference man. Pergamon Press, pp. 280–285.Google Scholar
Akber, SF. Correlation of radiation tolerance dose of normal human organs with organ weight, blood and water content. Am J Clin Oncol 2000; 23: 360–364.CrossRefGoogle ScholarPubMed
Figure 0

Table 1. Mean lethal radiation dose and organ weight of normal human organs

Figure 1

Figure 1. Correlation between mean lethal radiation dose and organ weight in human organs