  In radiation beam-profile measurements, an accurate positioning of the
detector with high position resolution is essential. For this purpose, we built
a scanning device capable of moving a detector in three dimensions using mainly
parts from a commercial 3D-printer. The accuracy and repeatability of movement
was tested with caliper, laser displacement sensor, and repeated $^{60}$Co
beam-profile measurements in a water phantom. The results from the caliper and
the sensor showed position accuracy for the scanner to be better than $\pm$150
$\mu$m. The standard deviation of the error in position from laser sensor
measurements was approximately 30 $\mu$m and the beam profile scans showed a
maximum deviation from the mean position of 50 $\mu$m. The effect of volume
averaging correction factors on $^{60}$Co beam-profile was investigated with
two different sized ionization chambers. The differences in the profiles were
reduced significantly after applying the correction factors.
