Font display weird

[vhptt]

I have a problem with Font Family. I create my own true type font by using Font Creator (on Window).
I use QPainter::drawText() function to draw a text with the font but there are a different between openSUSE and Window; different between each pointSize.

with pointSize <= 48: displaying ok on Window and openSUSE
with pointSize > 48: displaying ok on Window but on openSUSE look weird. The circle distorted (this problem come with every character which have circle vector in my font)
I attached screenshot.

Could some one tell me about the problem and how can I fix that ?