title: Low voltage CTPA for patients with suspected pulmonary embolism.
abstract: OBJECTIVE
  To test a low dose, low voltage protocol for the diagnosis of pulmonary embolism.
  
  
  METHODS
  50 Patients with clinically suspected pulmonary embolism underwent CTPA with 80kVp and 295mAs (test group) on a 64-row MDCT scanner. These patients were compared to a similar group of 50 patients scanned on the same scanner with the 120kVp protocol with automatic tube current modulation (control group). All patients received 100-110ml of a 370mgI/ml solution at 4.5cm(3)/s. Scans were compared for quantitative imaging parameters (attenuation and standard deviation in the main, right and left pulmonary arteries, in a lobar and segmental pulmonary artery and in the aorta) and for dose parameters (CTDI and DLP), using an unpaired t-test. Phantom measurements were also performed for image quality parameters and radiation dose.
  
  
  RESULTS
  Mean attenuation was significantly higher in the test group than in the control group in the main pulmonary trunk, in the right pulmonary artery, in the left pulmonary artery, in a lobar and segmental pulmonary artery and in the ascending aorta (all: p≤0.0001). Noise was significantly higher in the test group than in the control group, but contrast to noise ratio was not significantly different between the two protocols. Radiation dose was significantly lower in the test group than in the control group, as measured by CTDI, DLP and effective dose to organs (all: p<0.0001).
  
  
  CONCLUSIONS
  The use of 80kVp for pulmonary CTA significantly reduces patient radiation exposure, and significantly increases contrast medium attenuation in the pulmonary arteries, with no effect on the diagnostic quality of the exams.
authors.affiliation: Istituto di Radiologia, Policlinico GB Rossi, Azienda Ospedaliera Universitaria Integrata di Verona, P.le LA Scuro 10, 37134 Verona, Italy. gzamboni@hotmail.com
authors.forename: Giulia A
authors.initials: GA
authors.lastname: Zamboni
authors.forename: Stefania
authors.initials: S
authors.lastname: Guariglia
authors.forename: Alberto
authors.initials: A
authors.lastname: Bonfante
authors.forename: Cristian
authors.initials: C
authors.lastname: Martino
authors.forename: Carlo
authors.initials: C
authors.lastname: Cavedon
authors.forename: Roberto Pozzi
authors.initials: RP
authors.lastname: Mucelli
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000792:Angiography / Q000379:methods*; D001822:Body Burden; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011651:Pulmonary Artery / Q000000981:diagnostic imaging*; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging*; D011829:Radiation Dosage; D011835:Radiation Protection / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult