Caching: Uploading and using changed file

Hello,

most of the stuff is already implemented, but I could change it, if there is a better way.

The goal is that the user can upload one Logo, and this Logo is used on the website.

I have a picture box and a upload button. and following functionality (snippet):

        public Init()
        {
            _companyFolderAbs = Path.GetFullPath(Path.GetDirectoryName(Application.ExecutablePath) + @"\..\Resources\Uploaded_Files\" + _kundenNummer + "_" + _firmenName);
            _companyFolderRes = "Resources\\Uploaded_Files\\" + _kundenNummer + "_" + _firmenName;

            this.logoPictureBox.ImageSource = _companyFolderRes + "\\Logo.png";
        }

        private void UploadLogo(HttpPostedFile httpPostedFile)
        {
            string logoFile = "Logo.png";
            MemoryStream mem = new MemoryStream();
            httpPostedFile.InputStream.CopyTo(mem, 1024);

            mem.Position = 0;
            UploadStream(mem, logoFile);
        }

        private void UploadStream(Stream stream, string uploadFileName)
        {
            string path = Path.Combine(_companyFolderAbs, uploadFileName);
            using (FileStream outputFileStream = new FileStream(path, FileMode.Create))
            {
                stream.CopyTo(outputFileStream);
            }
        }

The Upload successfully overwrites the file. The Part that is missing is that the pictureBox then should use the new file.
I know it’s possible to set the Image from a Stream, but it would be easier to tell the App that the Resource / the file changed and needs reloading.

            mem.Position = 0;
            Image newLogo = Image.FromStream(mem);
            this.logoPictureBox.Image = newLogo;

Or do I always have to use a Stream to show a Logo if it’s possible that it will change? The problem is that even when I close and reopen the form, the old image is still cached. I tried stuff like Refresh(), Recreate(), Unsetting and Resetting the ImageSource, without success. But it seems when I press F5 it uses the new file.

Thanks in advance