Dialog dialog = new Dialog(context);
dialog.setContentView(R.layout.dialog);

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/patientsbg"
    android:orientation="vertical" >
</LinearLayout>

Dialog dialog = new Dialog(context);
dialog.setContentView(R.layout.dialog);
 dialog.getWindow().setBackgroundDrawable(new ColorDrawable(android.graphics.Color.TRANSPARENT));

<style name="Dialog_No_Border">
    <item name="android:windowIsFloating">true</item>
    <item name="android:windowBackground">#00000000</item>
</style>

dialog = new Dialog(this, R.style.Dialog_No_Border);