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Table 5 Variance (%) of uncertainties in tornado diagrams. A safety margin of 0.5 cm is added to the tumour size

From: Early health technology assessment of magnetic resonance-guided high intensity focused ultrasound ablation for the treatment of early-stage breast cancer

Treatment phase Tumour size (mm)a 10 20 30     
Treatment cell size (mm) 9×6 12×8 9×6 12×8 9×6 12×8 9×6 12×8
Parameter        Mean sd Mean sd
Positioning Time patient positioning 0.5 1.6 0.1 0.3 0.0 0.1 0.2 0.3 0.7 0.8
Time verification reachability 0.4 1.2 0.1 0.2 0.0 0.1 0.2 0.2 0.5 0.6
Time target definition 0.1 0.4 0.0 0.1 0.0 0.0 0.0 0.1 0.2 0.2
Chance of repositioning 0.5 1.6 0.1 0.3 0.0 0.1 0.2 0.3 0.7 0.8
Test Time MR scan 7.7 8.9 1.2 4.1 0.5 1.2 3.1 4.0 4.7 3.9
Time to place navigator 3.2 3.7 0.5 1.7 0.2 0.5 1.3 1.7 2.0 1.6
Time to perform treatment planning per coronal plane 0.6 0.7 0.1 0.3 0.0 0.1 0.2 0.3 0.4 0.3
Time to fill LUT 31.0 30.2 27.2 29.8 25.9 27.2 28.0 2.7 29.1 1.6
Time to perform test sonications and verify focal point 1.5 1.7 0.2 0.8 0.1 0.2 0.6 0.8 0.9 0.8
Chance of readjustment focal point 0.6 0.7 0.1 0.3 0.0 0.1 0.2 0.3 0.4 0.3
Therapeutic Time to perform therapeutic sonication 0.2 0.1 0.2 0.2 0.2 0.2 0.2 0.0 0.2 0.1
Cooling time after each sonication 52.8 47.8 69.2 60.9 71.8 69.2 64.6 10.3 59.3 10.8
Chance of resonication per coronal plane 0.8 0.7 1.1 1.0 1.1 1.1 1.0 0.2 0.9 0.2
Post treatment Time clinical ward 0.2 0.5 0.0 0.1 0.0 0.0 0.1 0.1 0.2 0.3
  1. Sensitivity (variance) was calculated by calculation of the swing square relatively to the total swing square. Hereby, the swing is the range of cost values for a given uncertainty
  2. aA safety margin of 0.5 cm was added to the tumour size