| Embryo dose estimates in body CT. | |
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MedLine Citation:
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PMID: 20308485 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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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. |
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Authors:
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Walter Huda; William Randazzo; Sameer Tipnis; G Donald Frey; Eugene Mah |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: AJR. American journal of roentgenology Volume: 194 ISSN: 1546-3141 ISO Abbreviation: AJR Am J Roentgenol Publication Date: 2010 Apr |
Date Detail:
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Created Date: 2010-03-23 Completed Date: 2010-05-06 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 7708173 Medline TA: AJR Am J Roentgenol Country: United States |
Other Details:
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Languages: eng Pagination: 874-80 Citation Subset: AIM; IM |
Affiliation:
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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 |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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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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