title: Perfusion scintigraphy versus 256-slice CT angiography in pregnant patients suspected of pulmonary embolism: comparison of radiation risks.
abstract: One aim of the current study was to determine normalized dose data for maternal radiosensitive organs and embryo/fetus from 256-slice CT pulmonary angiography (CTPA) performed on pregnant patients suspected of having pulmonary embolism. A second aim was to provide reliable maternal and fetal doses and associated radiation cancer risk estimates from 256-slice CTPA and lung perfusion scintigraphy (LPS) for comparison.
  
  
  METHODS
  Mathematic anthropomorphic phantoms were generated to simulate the average woman at early pregnancy and at the third, sixth, and ninth months of gestation. In each phantom, 0-3 additional 1.5-cm-thick fat tissue layers were added to derive 4 phantoms representing pregnant women with different body sizes. Monte Carlo methods were used to simulate low-dose 256-slice CTPA exposures on each of the 16 generated phantoms. Normalized organ and embryo/fetal dose data were derived for exposures at 80, 100, and 120 kV. Maternal effective dose and embryo/fetal dose from 256-slice CTPA and associated lifetime attributable risks of radiation cancer were determined for different body sizes and gestational stages and compared with corresponding data from LPS.
  
  
  RESULTS
  For an average-sized pregnant patient at the first trimester, the 256-slice CTPA exposure resulted in a maternal effective dose of 1 mSv and an embryo/fetal dose of 0.05 mGy. However, maternal effective dose considerably increased with body size, whereas embryo/fetal dose increased with both body size and gestational stage. Compared with LPS, low-dose CTPA to an average-sized pregnant patient resulted in a 30% higher maternal effective dose but a 3.4-6 times lower embryo/fetal dose. Nevertheless, LPS was associated with less aggregated radiation risk for an average-sized pregnant patient, with the difference from CTPA being increased further for larger patients.
  
  
  CONCLUSIONS
  Compared with CTPA performed with a modern wide-area CT scanner, LPS remains comparatively more dose-efficient.
authors.affiliation: Department of Medical Physics, Medical School, University of Crete, Heraklion, Crete, Greece kostas.perisinakis@med.uoc.gr.
authors.forename: Kostas
authors.initials: K
authors.lastname: Perisinakis
authors.affiliation: Medical Diagnostic Center "Ayios Therissos," Nicosia, Cyprus Department of Medical Physics, Medical School, Democritus University of Thrace, Panepistimioupolis, Dragana, Alexandroupolis, Greece; and.
authors.forename: Ioannis
authors.initials: I
authors.lastname: Seimenis
authors.affiliation: Department of Medical Physics, University Hospital of Heraklion, Heraklion, Crete, Greece.
authors.forename: Antonis
authors.initials: A
authors.lastname: Tzedakis
authors.affiliation: Department of Medical Physics, Medical School, University of Crete, Heraklion, Crete, Greece.
authors.forename: John
authors.initials: J
authors.lastname: Damilakis
mesh_terms: D000792:Angiography / Q000009:adverse effects*; D001345:Autoradiography; D002648:Child; D005260:Female; D005333:Fetus / Q000528:radiation effects; D006801:Humans; D008168:Lung / Q000098:blood supply / Q000000981:diagnostic imaging; D009381:Neoplasms, Radiation-Induced / Q000209:etiology; D055420:Perfusion Imaging / Q000009:adverse effects*; D011247:Pregnancy; D011248:Pregnancy Complications / Q000000981:diagnostic imaging*; D011297:Prenatal Exposure Delayed Effects / Q000209:etiology; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging*; D012039:Regional Blood Flow; D018570:Risk Assessment
keywords: CT pulmonary angiography; lung perfusion scintigraphy; patient dose; pulmonary embolism; radiation risk