title: Computed Tomography Colonography Phantom: Construction, Validation and Literature Review.
abstract: BACKGROUND
  Several dedicated computed tomography (CT) colonography phantoms have been described previously.
  
  
  OBJECTIVE
  To compare their pros and cons and describe the construction of a dedicated phantom that can be easily manufactured.
  
  
  METHODS
  We found 15 different phantom designs by literature search and compared their advantages and disadvantages based on their description and images. We tested various materials for density and mechanical properties and constructed a phantom from polypropylene pipes (30 mm and 50 mm in diameter, 52 cm in length). Haustral folds were created by heat shaping and 39 intermediate sessile polyps with a target size of 6-10 mm and two flat lesions were created from silicone. Nine polyps were attached to a fold. The model was placed in a 30-cm barrel filled with water to simulate attenuation of human body. Attenuation of polyps was compared to intermediate polyps found in patients.
  
  
  RESULTS
  None of the earlier colonic phantoms found in the literature incorporated all the properties that would ensure both reproducibility and validity of the model (including a rigid wall, density of the wall and polyps similar to human colon, at least two levels of distension and durability). In the present phantom, the average size of sessile polyps was 8.6 ± 0.9 mm and their density was 53 ± 24 HU. We found no significant difference in polyp density between simulated polyps in the phantom and polyps in human subjects (P = 0.70). All polyps, with the exception of one flat lesion, were detected by computer aided detection.
  
  
  CONCLUSIONS
  We constructed and validated a CT colonography phantom with correct density allowing performance of reproducible experiments.
authors.affiliation: Department of Radiology, First Faculty of Medicine, Charles University in Prague, Prague, Czech Republic.
authors.forename: Lukas
authors.initials: L
authors.lastname: Lambert
authors.affiliation: Department of Radiology, First Faculty of Medicine, Charles University in Prague, Prague, Czech Republic; Department of Psychiatry, First Faculty of Medicine, Charles University in Prague, Prague, Czech Republic.
authors.forename: Alena
authors.initials: A
authors.lastname: Lambertova
authors.affiliation: Department of Radiology, First Faculty of Medicine, Charles University in Prague, Prague, Czech Republic.
authors.forename: Jan
authors.initials: J
authors.lastname: Danes
authors.affiliation: Fourth department of Internal Medicine, First Faculty of Medicine, Charles University in Prague, Prague, Czech Republic.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Grusova
keywords: CT Colonography; Low-Dose; Phantom; Polyp; Review