How to solve this error. image url is binding again and again in treeview

hi. i used for each only.. i posted full coding. you can see what is the problem

private void bindingroodrecord()

{

sql = "EXEC [sp_parent_record]"; //stored procedur to get parent records

SqlCommand cmd = new SqlCommand(sql, objConn);
SqlDataAdapter da = new SqlDataAdapter(cmd);
DataTable dt1 = new DataTable();
da.Fill(dt1);
Session["parentnode"] = dt1;

PopulateNodes(dt1, TreeView1.Nodes); ///////// for parent node

}

private void PopulateNodes(DataTable dt, TreeNodeCollection nodes)
{
foreach (DataRow dr in dt.Rows)
{
TreeNode tn = new TreeNode();

tn.Text = dr["columnfield"].ToString().Trim();

tn.Value = dr["code_webcategory_id"].ToString().Trim();
tn.ImageUrl = string.Format("image.aspx?category={0}&width=50", tn.Value);
nodes.Add(tn);


tn.PopulateOnDemand = (Convert.ToInt32(dr["childnodecount"]) > 0);

}


}
The above coding works fine.

NOTE: image.aspx, image comes from database(which comes as byte) and then writting as image using System.Drawing.Image bitmap = System.Drawing.Image.FromStream(stream),......the image comes from database and binds in tn.imageurl correctly.

so, right now as i have 100 records it binds image 100 time which is ok.

now the below coding to bind child notes

protected void TreeView1_TreeNodePopulate(object sender, TreeNodeEventArgs e)
{


PopulateSubLevel(Convert.ToInt32(e.Node.Value), e.Node); // i am getting parent node when user click (populate)on treeview to form a child node for parent node.


}

private void PopulateSubLevel(int parentid, TreeNode parentNode)
{

SqlCommand cmd = new SqlCommand("sp_getchildrecords", objConn);/// this is the stored procedure to get child node using parent id.
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.Add("@parentID", SqlDbType.Int).Value = parentid;
SqlDataAdapter da = new SqlDataAdapter(cmd);
DataTable dt = new DataTable();
da.Fill(dt);
Session["childnode"] = dt;
Session["childnodess"] = parentNode;
TreeNode childrecords = (TreeNode)Session["childnodess"];

PopulateNodes(dt, childrecords.ChildNodes); // to form child nodes


}
this also works fine. but,

Now, consider the child node has 10 records. once the populateNodes function gets over , it calls image.aspx to get an image. Now it binds 110 time again instead of binding 10 times.

Hi Syed, as you said. i worked on that. now it binds for child node only. but the issues the image shows only for child node. parent node is showing empty image.