How to cast checkbox values in HTML5 with C# and razor style?

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C#

.NET

checkbox

HTML5

Razor

I need some help with a .NET issue
I cant take the checkbox values using razor style in HTML with C#
This is my code and the form that i`m trying to cast the data:

'''''
HTML
TituloNegrita: @Html.CheckBox("txt_TituloNegrita")
''''
myStyle.TituloNegrita = Convert.ToBoolean(form["txt_TituloNegrita"].ToString());

Thanks ;)