Document Detail


Embryo dose estimates in body CT.
MedLine Citation:
PMID:  20308485     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
OBJECTIVE: The purpose of this article is to develop a method for estimating embryo doses in CT. MATERIALS AND METHODS: Absorbed doses to the uterus (embryo) of a 70-kg woman were estimated using the ImPACT CT Patient Dosimetry Calculator. For a particular CT scan length, relative uterus doses and normalized plateau uterus doses were determined for a range of commercial CT scanners. Patient size characteristics were obtained from cross-sectional axial images of 100 consecutive patients (healthy women undergoing unenhanced pelvic CT examinations). For each patient, the diameter of a water cylinder with the same mass as the patient's pelvis was computed. Relative dose values were generated for cylinder diameters ranging from 16 to 36 cm at x-ray tube voltages between 80 and 140 kV. RESULTS: Values of relative uterus dose increased monotonically with increasing scan length, independently of scanner model, and reached a plateau for scan lengths greater than approximately 50 cm. The average normalized plateau uterus dose for all scanners was approximately 1.4 and showed interscanner differences of less than 10% for modern scanners operated at 120 kV. Normalized plateau doses show little dependence on the x-ray tube voltage used to perform the CT examination. Our results show that the uterus dose estimate in an abdominal or pelvis CT examination performed on a 70-kg patient is about 40% higher than the reported value of the volume CT dose index (CTDI(vol)). The pelvis of a 70-kg patient may be modeled as a water cylinder with a diameter of 28 cm and has an average anteroposterior dimension of 22 cm. For constant CT technique factors, embryo dose estimates for a 45-kg patient would be approximately 18% higher than those for a 70-kg patient, whereas the corresponding dose estimates in a 120-kg patient would be approximately 37% lower. CONCLUSION: Embryo doses can be estimated using relative uterus doses, normalized plateau uterus doses, and CTDI(vol) data with correction factors for patient size.
Authors:
Walter Huda; William Randazzo; Sameer Tipnis; G Donald Frey; Eugene Mah
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  AJR. American journal of roentgenology     Volume:  194     ISSN:  1546-3141     ISO Abbreviation:  AJR Am J Roentgenol     Publication Date:  2010 Apr 
Date Detail:
Created Date:  2010-03-23     Completed Date:  2010-05-06     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7708173     Medline TA:  AJR Am J Roentgenol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  874-80     Citation Subset:  AIM; IM    
Affiliation:
Department of Radiology and Radiological Science, Medical University of South Carolina, 96 Jonathan Lucas St, MSC 323, Charleston, SC 29412-3230, USA. huda@musc.edu
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MeSH Terms
Descriptor/Qualifier:
Body Size
Female
Fetus / radiation effects*
Humans
Monte Carlo Method
Phantoms, Imaging
Pregnancy
Radiation Dosage*
Radiation Protection
Radiometry / methods
Tomography Scanners, X-Ray Computed
Tomography, X-Ray Computed
Uterus / radiation effects*
Whole Body Imaging*

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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