title: Digital tomosynthesis of the chest: comparison of patient exposure dose and image quality between standard default setting and low dose setting.
abstract: OBJECTIVE
  To determine the optimum low dose (LD) digital tomosynthesis (DT) setting, and to compared the image quality of the LD DT with that of the standard default (SD) DT.
  
  
  METHODS
  Nine DT settings, by changing tube voltage, copper filter, and dose ratio, were performed for determining the LD setting. Among combinations of DT setting, a condition providing the lowest radiation dose was determined. Eighty artificial nodules less than 1 cm in diameter (subcentimeter nodules: 40, micronodules less than 4 mm: 40) were attached to a Styrofoam and a diaphragm of the phantom. Among these, 38 nodules were located at the periphery of the lung (thin area) and 42 nodules were located at the paravertebral or sub-diaphragmatic area (thick area). Four observers counted the number of nodules detected in the thick and thin areas. The detection sensitivity in SD and LD settings were calculated separately. Data were analyzed statistically.
  
  
  RESULTS
  The lowest LD setting was a combination of 100 kVp, 0.3 mm additional copper filter, and a 1 : 5 dose ratio. The effective dose for the LD and SD settings were 62 µSv and 140 µSv, separately. A 56.7% dose reduction was achieved in the LD setting compared with the SD setting. Detection sensitivities were not different between the SD and the LD settings except between observers 1 and 2 for the detection of micronodules in the thick area.
  
  
  CONCLUSIONS
  LD DT can be effective in nodule detection bigger than 4 mm without a significant decrease in image quality compared with SD DT.
authors.affiliation: Department of Radiology, Hallym University Sacred Heart Hospital, Anyang 431-070, Korea.
authors.forename: Hye Sun
authors.initials: HS
authors.lastname: Hwang
authors.forename: Myung Jin
authors.initials: MJ
authors.lastname: Chung
authors.forename: Kyung Soo
authors.initials: KS
authors.lastname: Lee
mesh_terms: D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D011856:Radiographic Image Enhancement / Q000379:methods*; D012680:Sensitivity and Specificity; D003074:Solitary Pulmonary Nodule / Q000000981:diagnostic imaging
keywords: Digital radiography; Radiation dose; Tomographic imaging