There's really no definate way to tell from this angle. As Joy said you need a picture of babys genitalia ...
how far along were you when you had the scan? I went at 14 w and they told me it was too early (some people do get more cooperative us techs that will look) I found out at 18w and again at 20w to confirm a little girl. When I had my DS it was very prominent that he was a boy - with the girls I am always a little fuzzy on the pics... but you can clearly see a protruding little boy part if they can get a good angle.
i read in some web page...if u see 3 or 4 parallel lines of private part then its girl...and if one line and broad area then its boy
If you call your dr's office you can ask them to look at the ultrasound pics that will be in your file and they may be able to tell you.
You would need to post a sonogram picture of a baby's genitalia in order to determine that.