Skip Navigation


Radiation Protection Dosimetry Advance Access originally published online on March 15, 2008
Radiation Protection Dosimetry 2008 130(2):236-238; doi:10.1093/rpd/ncm501
This Article
Right arrow Abstract Freely available
Right arrow FREE Full Text (PDF) Freely available
Right arrowOA All Versions of this Article:
130/2/236    most recent
ncm501v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Google Scholar
Right arrow Articles by Rahman, M. S.
Right arrow Articles by Zaman, M. A.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Rahman, M. S.
Right arrow Articles by Zaman, M. A.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

© The Author 2008. Published by Oxford University Press. All rights reserved
The online version of this article has been published under an open access model. Users are entitled to use, reproduce, disseminate, or display the open access version of this article for non-commercial purposes provided that: the original authorship is properly and fully attributed; the Journal and Oxford University Press are attributed as the original place of publication with the correct citation details given; if an article is subsequently reproduced or disseminated not in its entirety but only in part or as a derivative work this must be clearly indicated. For commercial re-use, please contact journals.permissions@oxfordjournals.org.

Body radioactivity and radiation dose from 40K in Bangladeshi subjects measured with a whole-body counter

M. Sohelur Rahman1,*, A. S. Mollah2, A. Begum1, M. Islam3 and M. A. Zaman4

1 Health Physics Division, Atomic Energy Centre, 4 Kazi Nazrul Islam Avenue, Ramna, Dhaka-1000, Bangladesh
2 Nuclear Safety and Radiation Control Division, 4 Kazi Nazrul Islam Avenue, Ramna, Dhaka-1000, Bangladesh
3 Radiation Monitoring and Waste Management Laboratory, Institute of Nuclear Science and Technology, Atomic Energy Research Establishment, PO Box 3787, Savar, Dhaka, Bangladesh
4 Department of Physics, Jahangirnagar University, Savar, Dhaka, Bangladesh

* Corresponding author: msrahman74{at}hotmail.com, msrahman1974{at}yahoo.com

Received August 24, 2007, amended November 25, 2007, accepted December 26, 2007


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 ACKNOWLEDGEMENTS
 REFERENCES
 

A group of subjects of Bangladeshi adults from both sexes were studied for internal radioactivity and effective dose by measuring the whole-body activity of naturally occurring 40K using a whole-body counter. The mean activity concentration in the whole body and effective dose due to naturally occurring 40K for the average male were found to be 2.0 ± 0.4 Bq·g–1 and 100 ± 26 µSv·y–1, respectively and those for the average female were 1.7 ± 0.3 Bq·g–1 and 100 ± 20 µSv·y–1, respectively. The mean activity concentration in the whole body and effective dose for both sexes were 1.9 ± 0.4 Bq·g–1 and 100 ± 25 µSv·y–1, respectively. The effective dose from 40K for subjects is below the value reported by the UNSCEAR.


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 ACKNOWLEDGEMENTS
 REFERENCES
 
A measurement of body composition in human is useful in the assessment of obesity and in research on the effects of stress, malnutrition and the response to disease or therapy. In vivo human body composition is assessed by indirect methods, including densitometry by underwater weighing, measurement of total body water by isotope dilution and measurement of total body content by whole-body counting. Among these methods, whole-body counting of 40K is used frequently because it non-invasive and involves minimal subject inconvenience(1).

Natural potassium is a mixture of three isotopes: 39K, 40K and 41K with mass percentages of 93.08, 0.0118 and 6.91, respectively(2). A typical 20-y-old 70-kg adult male contains about 0.140 kg potassium(3) with about 3,700 Bq of 40K(4). The 1461 keV gamma rays emitted from 40K in the body can be detected with a whole-body counter.

The purpose of the present study is to investigate the mean activity concentration in the whole-body and the internal radiation dose from naturally occurring 40K to the population of the People's Republic of Bangladesh.


   MATERIALS AND METHODS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS AND DISCUSSION
 ACKNOWLEDGEMENTS
 REFERENCES
 
Measurements of 40K were carried out on a group of healthy Bangladeshi subjects of both sexes; most of them work at the Institute of Nuclear Science and Technology (INST) and nearby Institutions.

Whole-body counting system
Naturally occurring 40K was determined with an INST whole-body counter (WBC) employing a single detector in the chair geometry. Details description of such an arrangement can be found elsewhere(5). The counter employs a low background shielded room, and a NaI(Tl) scintillation detector of crystal size of 12.7 cm diameter x 12.7 cm in height in a chair geometry. The detector and bed are mounted in an iron frame. To reduce the external background radiation, the detector is surrounded by a shielding material consisting of lead and iron. The thickness of the lead and iron shields are 3.5 and 2.5 cm, respectively. About 90% average external background radiation was reduced in the energy ranging from 0.1 to 3 MeV using this shielding configuration(6). Additional 0.93 mm of copper lining was used inside of the lead and iron shielding in order to reduce the low energy background, which is required to detect low energy photon (<100 keV). The detector is connected to a 35+ Canberra+ multichannel analyser, which is connected in turn to a PCTM computer system.

Calibration of WBC
The WBC was calibrated using a water phantom of weight 63.5 kg, which is a typical weight of Asian reference man(6), filled with KCI solution. The uniform activity distribution was assumed in the phantom. The phantom representing lungs, heart, liver and kidneys of an adult human body. The calibration coefficient was determined by dividing the net count rate for the 40K phantom by the amount of 40K in the phantom. The background count rate was measured using the same adult phantom that was used for 40K calibration, filled with only water. Weight correction was not done in this study. Therefore, uncertainty due to difference in weight between the phantom and the measured subject was included in the uncertainty value given for the subject.

Subjects monitoring
Subjects were selected randomly from among those assumed to be free of internal contamination by artificial radionuclides. The age of 90 male subjects ranged from 50 to 22 y, and the age of 35 female subjects ranged from 46 to 20 y. The weight of male subjects ranged from 73 to 50 kg, while the female subjects ranged from 70 to 40 kg. The heights of males ranged from 182 to 152 cm and the heights of females ranged from 167 to 149 cm. Subjects are positioned in chair geometry for about a 1 h counting time.


   RESULTS AND DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
ACKNOWLEDGEMENTS
 REFERENCES
 
The gamma-ray energy spectrum
The prominent photo-peak that can be observed from the spectrum is due to the photo-peak of the naturally occurring radionuclide, 40K at 1460 keV. In the {gamma}-ray spectrum, other radionuclides such as 238U, 232Th and 137Cs were observed but the net peak area under the photo-peak energy of interest was insignificant i.e. at the background level. For this reason, only 40K activity has been determined in the present work.

Body 40K activity
The radioactivity due to radionuclides was measured from the relation,


Formula 501M1

(1)

Where, CPS is the count per second; Eg is the efficiency of the detector for the energy of interest for 63.5 kg phantom = 0.0142; Ig is the gamma emission probability = 0.11.

Eg in Equation (1) depends on subject weights and geometries.

The mean activity concentration in the whole-body (Am) was calculated from the following relation


Formula 501M2

(2)

Where, A is the activity in Bq; W is the body weight in grams.

Internal dose from 40K
The calculation of body effective dose due to naturally occurring 40K was based on the modified formula recommendation by the medical internal radiation dose Committee of the Society of Nuclear Medicine(7). While calculating the dose from gamma radiation, a correction for body weight was considered. Effective dose was then calculated from the following equation:


Formula 501M3

(3)
where, D is the the effective dose (µSv·y–1); Am is the mean activity concentration in the whole-body due to 40K (Bq·g–1); DCFβ is the dose conversion factor for beta ray of 40K (52.60 µSv·y–1 per Bq·g–1); DCF{gamma} is the dose conversion factor for gamma ray of 40K (4.82 µSv·y–1 per Bq·g–1); W is the average body weight for a subject at a given age in kg; and a and b are modifying constants for body weight. For individuals between 40 and 70 kg, the values a = 0.359, and b = 0.241 are considered(8).

In the present work, it has been found that the average annual effective dose for male is slightly higher than that for female. Moreover, the average effective dose due to only naturally occurring radionuclides for non-occupational workers is slightly higher than that for occupational workers. It may be mentioned here that no artificial radionuclides were found in the body of occupational workers, which means that the occupational workers are free from radioactive contamination. The maximum effective dose due to naturally occurring 40K was 160 µSv.y–1 for male and 130 µSv·y–1 for female.

Table 1 presents a summary of the results of the mean activity concentration in the whole-body and effective dose from 40K estimated in this work and also some data from the UNSCEAR 1993 report for comparison.


View this table:
[in this window]
[in a new window]

  		Table 1. Summary of results of the mean activity concentration in the whole-body and effective dose from 40K of Bangladeshi adults.

 

   ACKNOWLEDGEMENTS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 ACKNOWLEDGEMENTS
REFERENCES
 
The authors convey special thanks to all personnel who gave their valuable times and supports for the measurement of whole-body counts.


   REFERENCES
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 ACKNOWLEDGEMENTS
 REFERENCES
 

  1. Lykken G. I., Lukaski H. C., Bolonchuk W. W., Sandstead H. H. Potential errors in body composition as estimated by whole-body scintillation counting. J. Lab. Clin. Med (1983) 101:651–658.[Web of Science][Medline]
  2. United Nation Scientific Committee on the Effects of Atomic Radiation. Sources and effects of ionizing radiation. (1993) United Nation Publications, New York.
  3. ICRP. Report of the task group on reference man. (1975) Oxford: Pergamon Press. ICRP Publication 23.
  4. Samat S. B., Green S., Beddoe A. H. The 40K activity of one gram of potassium. Phys. Med. Biol (1997) 42:407–413.[CrossRef][Web of Science][Medline]
  5. Tung C. J., Chou H. P., You C. C., Lan C. Y., Tseng C. L. Whole-body counting for internal radionuclide contamination. Chin. J. Radiol (1985) 10:231–242.
  6. Mollah A. S. Intercalibration of in vivo counting systems using an Asian phantom, results of a co-ordinated research project 1996–1998. (2003) 74–76. IAEA-TECDOC-1334.
  7. Snyder W. S., Ford M. R., Warner G. C., Fisher H. L. Jr. Estimates of absorbed fractions for monoenergetic photon sources uniformly distributed in various organs of a heterogeneous phantom. J. Nucl. Med. 52((Suppl. 3)).
  8. Kumar M., Sharma L. N. Poattsium-40 content in male radiation workers at Narora Atomic Power Station. Radiat. Prot. Environ (2001) 24(1–2):S36–S41.

Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?



This Article
Right arrow Abstract Freely available
Right arrow FREE Full Text (PDF) Freely available
Right arrowOA All Versions of this Article:
130/2/236    most recent
ncm501v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Google Scholar
Right arrow Articles by Rahman, M. S.
Right arrow Articles by Zaman, M. A.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Rahman, M. S.
Right arrow Articles by Zaman, M. A.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?