File_DICOM::getValue()

require_once('File/DICOM.php');

$dicom_file = new File_DICOM();
$res = $dicom_file->parse('test.dcm');

// check for errors
if (PEAR::isError($res)) {
    die($res->getMessage());
}

echo 'this value: '.$dicom_file->getValue('PatientName')."\n";
echo 'Should be the same as this value: '.$dicom_file->getValue(0x0010, 0x0010)."\n";