Diapositive 1

OF: small fields

-5.0%

-4.0%

-3.0%

-2.0%

-1.0%

0.0%

1.0%

2.0%

3.0%

4.0%

5.0%

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0

Side of equivalent square field size at isocenter (cm)

Relative difference normalized to EFD OF

Exradin W1 Cal. A

Exradin W1 Cal. B

Exradin W1 Cal. C

Pinpoint

Relative differences of OF normalized to EFD-3G OF.

OF are referred to a 10 x 10 cm

field size.

Parallel to beam axis

Figure 1. Calibration plate with the scintillator in the maximum fiber configuration (left) and

minimum fiber configuration (right).

Perpendicular to beam axis

The calibration methodology proposed by

the manufacturer is not appropriate for

measuring output factors for small fields.

Calibration using smaller fields and the

detector axis parallel to beam axis should

be used.

These results show that the CRL and gain

depend on field size and orientation of the

scintillator.

Organic scintillator

(W1 Standard Imaging)