Document Detail

Effective doses to patients undergoing thoracic computed tomography examinations.
MedLine Citation:
PMID:  10841385     Owner:  NLM     Status:  MEDLINE    
The purpose of this study was to investigate how x-ray technique factors and effective doses vary with patient size in chest CT examinations. Technique factors (kVp, mAs, section thickness, and number of sections) were recorded for 44 patients who underwent a routine chest CT examination. Patient weights were recorded together with dimensions and mean Hounsfield unit values obtained from representative axial CT images. The total mass of directly irradiated patient was modeled as a cylinder of water to permit the computation of the mean patient dose and total energy imparted for each chest CT examination. Computed values of energy imparted during the chest CT examination were converted into effective doses taking into account the patient weight. Patient weights ranged from 4.5 to 127 kg, and half the patients in this study were children under 18 years of age. All scans were performed at 120 kVp with a 1 s scan time. The selected tube current showed no correlation with patient weight (r2=0.06), indicating that chest CT examination protocols do not take into account for the size of the patient. Energy imparted increased with increasing patient weight, with values of energy imparted for 10 and 70 kg patients being 85 and 310 mJ, respectively. The effective dose showed an inverse correlation with increasing patient weight, however, with values of effective dose for 10 and 70 kg patients being 9.6 and 5.4 mSv, respectively. Current CT technique factors (kVp/mAs) used to perform chest CT examinations result in relatively high patient doses, which could be reduced by adjusting technique factors based on patient size.
W Huda; E M Scalzetti; M Roskopf
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Medical physics     Volume:  27     ISSN:  0094-2405     ISO Abbreviation:  Med Phys     Publication Date:  2000 May 
Date Detail:
Created Date:  2000-09-25     Completed Date:  2000-09-25     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0425746     Medline TA:  Med Phys     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  838-44     Citation Subset:  IM    
Department of Radiology, SUNY Upstate Medical University, Syracuse, New York 13210, USA.
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MeSH Terms
Biophysical Phenomena
Body Weight
Child, Preschool
Middle Aged
Phantoms, Imaging
Radiation Dosage
Radiography, Thoracic* / instrumentation
Tomography, X-Ray Computed* / instrumentation

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