Dose Course 2018_Flipping book

Scanner homogeneity

▪ Pixel value varies with position on the scanner plate due to light scattering differences:

0,9933

relative pixel value

position

▪ small effects (<1%) when moving films parallel to scan direction ▪ up to 8% variation when moving films perpendicular to the scan direction, dose dependent. <2% within 5 cm from the scanner axis for D<2Gy)

1,0001

0,9273

0,9891

1

0,9859

0,9237

0,9992

Scan direction

▪

2D correction for “full” films

0,9939

▪

Dose dependent

▪

Scanner dependent

EPSON Pro 1680 Expression scanner:

Paelinki et al PMB 52 (2007) and Fuss et al PMB 52 (2007)

Fiandra et al MP 33 (2006)

Epson 10000XL scanner :

Scan direction

Ferreira et al. PMB54 (2009)