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Table 2 Noise and CNR at different dose levels with FBP, HIR and MIR

From: Emphysema quantification using chest CT: influence of radiation dose reduction and reconstruction technique

  Noise (aorta) Noise (fat) CNR
Routine dose
 FBP 37.5 (28.1–42.8) 30.2 (25.4–52.0) 4.8 (3.0–5.5)
 HIR 18.4 (15.0–22.2)a 18.2 (14.6–23.3)a 8.3 (6.7–10.1)a
 MIR 11.4 (9.5–12.5)a 11.5 (9.8–15.2)a 13.0 (10.7–15.9)a
45% reduced dose
 FBP 46.6 (38.9–58.4)a 39.3 (31.6–78.9)a 3.3 (2.1–4.5)a
 HIR 23.2 (20.5–26.5)a 23.5 (17.5–27.8)a 6.7 (5.5–8.1)a
 MIR 12.3 (11.3–14.4)a 13.5 (10.7–17.2)a 11.4 (9.0–13.7)a
60% reduced dose
 FBP 60.2 (47.8–81.4)a 50.8 (42.5–94.6)a 2.5 (1.7–3.5)a
 HIR 26.4 (22.9–31.8)a 28.1 (21.4–34.7)a 5.5 (4.4–6.8)a
 MIR 13.7 (12.2–16.5)a 13.9 (12.7–17.2)a 11.4 (8.9–12.4)a
75% reduced dose
 FBP 80.0 (61.4–108.5)a 62.8 (47.5–142.6)a 2.3 (1.2–2.7)a
 HIR 32.6 (28.5–37.8) 30.4 (24.7–39.6) 4.7 (3.7–5.7)
 MIR 16.4 (14.1–19.7)a 15.1 (13.8–19.1)a 9.2 (7.9–11.3)a
  1. Values are presented as median (interquartile range)
  2. aStatistically significant difference compared to FBP at routine dose with a Bonferroni corrected p value of 0.017
  3. CNR contrast-to-noise ratio, FBP filtered back projection, HIR hybrid iterative reconstruction, MIR model-based iterative reconstruction