+ * \brief constructor
+ * @param begin iterator (inside the gdcmParser chained list)
+ * on the first Header Entry (i.e Dicom Element)
+ * related to this "STUDY" part
+ * @param end iterator (inside the gdcmParser chained list)
+ * on the last Header Entry (i.e Dicom Element)
+ * related to this 'STUDY' part
+ * @param ptagHT pointer to the HTable (gdcmObject needs it
+ * to build the gdcmHeaderEntries)
+ * @param plistEntries pointer to the chained List (gdcmObject needs it
+ * to build the gdcmHeaderEntries)