How to pinvoke a structure in C# ?

typedef struct _SCANNER_NOTIFICATION {
	
	ULONG ProcessId;
	USHORT FileNameLength;	//string length
	WCHAR FileName[1];	//Variable length string

} SCANNER_NOTIFICATION

[StructLayoutAttribute(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
       public struct SCANNER_NOTIFICATION
       {

           /// ULONG->int
           public int ProcessId;

           /// USHORT->short
           public short FileNameLength;

           /// WCHAR[1]
           public IntPtr FileName;
       }