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Offset Property (DicomElement)

Summary

Gets the byte offset of the element from the beginning of the file

Syntax

WinRT C#

C++

public long Offset {get;}

Public ReadOnly Property Offset As Long

public long Offset {get;}

 get_Offset();

public: 
property int64 Offset { 
   int64 get(); 
}

Property Value

The byte offset of the element from the beginning of the file

Remarks

Depending on the transfer syntax and value representation, a DICOM Element is stored in a file as one of the following

Tag(4 bytes), VR(4 bytes), Value Length (4 bytes), Value
Tag(4 bytes), VR(2 bytes), Value Length (2 bytes), Value
Tag(4 bytes), Value Length (4 bytes), Value

The Offset property returns the byte offset for the DicomElement in the file. If you seek to this offset in the DICOM file, the next 4 bytes will be the Tag (group, element) of the DICOM element.

Example

This example displays information about each element in a DicomDataSet including: * Tag * Name * Offset * Value offset * Value length

using Leadtools; 
using Leadtools.Dicom; 
 
/// 
private void DicomDataSetOffsetTest(DicomDataSet ds) 
{ 
   DicomElement element = ds.GetFirstElement(null, false, true); 
   while (element != null) 
   { 
      DumpElementValue(element); 
      element = ds.GetNextElement(element, false, true); 
   } 
} 
 
private string GetElementString(DicomElement p) 
{ 
   if (p == null) 
      return string.Empty; 
   return string.Format("({0:X4},{1:X4})", p.Tag >> 0x10, p.Tag & 0xFFFF); 
} 
 
private string Truncate(string s, int length) 
{ 
   if (s.Length > length) 
      return s.Substring(0, length); 
   return s; 
} 
 
private void DumpElementValue(DicomElement element) 
{ 
   DicomTag tag = DicomTagTable.Instance.Find(element.Tag); 
   string name = string.Empty; 
   if (tag != null) 
   { 
      name = tag.Name; 
   } 
   Console.WriteLine(@"{0} {1,-30} 0x{2:X8} 0x{3:X8} {4}", 
      GetElementString(element), 
      Truncate(name, 30), 
      element.Offset, 
      element.ValueOffset, 
      element.ValueLength); 
}

Imports Leadtools 
Imports Leadtools.Dicom 
 
''' 
Private Sub DicomDataSetOffsetTest(ByVal ds As DicomDataSet) 
   Dim element As DicomElement = ds.GetFirstElement(Nothing, False, True) 
   Do While element IsNot Nothing 
      DumpElementValue(element) 
      element = ds.GetNextElement(element, False, True) 
   Loop 
End Sub 
 
Private Sub DumpElementValue(ByVal element As DicomElement) 
   Dim tag As DicomTag = DicomTagTable.Instance.Find(element.Tag) 
   Dim name As String = String.Empty 
   If tag IsNot Nothing Then 
      name = tag.Name 
   End If 
   Console.WriteLine("{0} {1,-30} 0x{2:X8} 0x{3:X8} {4}", GetElementString(element), Truncate(name, 30), element.Offset, element.ValueOffset, element.ValueLength) 
End Sub 
 
Private Function GetElementString(ByVal p As DicomElement) As String 
   If p Is Nothing Then 
      Return String.Empty 
   End If 
   Return String.Format("({0:X4},{1:X4})", p.Tag >> &H10, p.Tag And &HFFFF) 
End Function 
 
Private Function Truncate(ByVal s As String, ByVal length As Integer) As String 
   If s.Length > length Then 
      Return s.Substring(0, length) 
   End If 
   Return s 
End Function