有没有办法使用纯C#将PDF转换为PDF/A (如果Telerik不支持)

using iTextSharp.text;
using iTextSharp.text.pdf;
using iTextSharp.text.pdf.parser;

public void ConvertToPDFA(string sourcePath, string destinationPath)
{
    // Load the source PDF document
    PdfReader reader = new PdfReader(sourcePath);

    // Create the output PDF/A document
    Document document = new Document();
    PdfAWriter writer = PdfAWriter.GetInstance(document, new FileStream(destinationPath, FileMode.Create), PdfAConformanceLevel.PDF_A_1B);

    // Open the document for writing
    document.Open();

    // Iterate through each page of the source PDF
    for (int pageNumber = 1; pageNumber <= reader.NumberOfPages; pageNumber++)
    {
        // Get the page from the source PDF
        PdfImportedPage page = writer.GetImportedPage(reader, pageNumber);

        // Add the page to the output PDF/A document
        writer.DirectContent.AddTemplate(page, 0, 0);
    }

    // Close the output PDF/A document
    writer.Close();
    document.Close();
}