Korean J Radiol.  2008 Apr;9(2):102-110. 10.3348/kjr.2008.9.2.102.

Estimating the Absorbed Dose to Critical Organs During Dual X-ray Absorptiometry

• Dizaji MM
• Sharafi AA
• Larijani B
• Mokhlesian N
• Hasanzadeh H

• KMID: 1098188
• DOI: http://doi.org/10.3348/kjr.2008.9.2.102

Abstract

OBJECTIVE
The purpose of this study is to estimate a patient's organ dose (effective dose) during performance of dual X-ray absorptiometry by using the correlations derived from the surface dose and the depth doses in an anthropomorphic phantom. MATERIALS AND METHODS: An anthropomorphic phantom was designed and TLDs (Thermoluminescent Dosimeters) were placed at the surface and these were also inserted at different depths of the thyroid and uterus of the anthropomorphic phantom. The absorbed doses were measured on the phantom for the spine and femur scan modes. The correlation coefficients and regression functions between the absorbed surface dose and the depth dose were determined. The derived correlation was then applied for 40 women patients to estimate the depth doses to the thyroid and uterus. RESULTS: There was a correlation between the surface dose and depth dose of the thyroid and uterus in both scan modes. For the women's dosimetry, the average surface doses of the thyroid and uterus were 1.88 (micro)Gy and 1.81 (micro)Gy, respectively. Also, the scan center dose in the women was 5.70 (micro)Gy. There was correlation between the thyroid and uterus surface doses, and the scan center dose. CONCLUSION: We concluded that the effective dose to the patient's critical organs during dual X-ray absorptiometry can be estimated by the correlation derived from phantom dosimetry.

Keyword

Dual X-ray absorptiometry; TLD dosimetry; Phantom; Absorbed dose; Critical organs

MeSH Terms

*Absorptiometry, Photon
Female
Femur/radiography
Humans
Linear Models
Middle Aged
*Models, Anatomic
*Phantoms, Imaging
*Radiation Dosage
Spine/radiography
Thyroid Gland/*radiation effects
Uterus/*radiation effects

Figure

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  Fig. 1 Calibration curve of TLDs.

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  Fig. 2 Correction factor curve for TLDs.

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  Fig. 3 Front view of anthropomorphic phantom with depth probes.

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  Fig. 4 Anthropomorphic phantom in measurement position.

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  Fig. 5 Scatter plot between centers of scan dose with thyroid surface dose (A) and uterus surface dose (µGy) (B) with 95% confidence interval.

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  Fig. 6 Scatter plot between uterus surface dose and thyroid surface dose (µGy) with 95% confidence interval.

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