How to add new fonts to Itext using java

when I want to use a font is iText I do the following:

protected final static Font FONT_SIZE_11_BOLD = new Font(Font.HELVETICA, 11f, Font.BOLD);

and then I can use it whereever I want, as follows:

monthSize11 = new Chunk(month, FONT_SIZE_11_BOLD);

I want to use Arial instead of HELVETICA, but Arial is not directly available. I mean, I cannot do

new Font(Font.ARIAL, 11f, Font.BOLD);

because Arial is not defined at the Font class, but the Arial.ttf file is at my System under C:\WINDOWS\Fonts. The question is how I can bind the Arial.ttf file to iText and how can I use it.

Many thnaks in advance.

EDIT: I would like to use own fonts. I mean, I have a file called "myCompany.ttf" where own fonts have been defined and at some places I must use. The problem is not only with Arial.