PACS archives plan for the undesirable

摘要

Abstract: It is argued that in the design of a PACS archive in addition to the performance aspects in routine clinical use, the problems to be expected in undesirable circumstances need to be considered. In this paper the possibility to reconstruct the image database after a corruption and to convert the archive to a new storage medium are analyzed. Two different ways to organize the image database are considered: In the first set-up (A) the images are stored in historical sequence, as they are acquired. The storage facility is logically considered as a consecutive range of addresses, separation in volumes is neglected in the storage strategy. In the second set-up (B) the storage facility is considered as a set of volumes; images are assigned to volumes in such a way that in most cases all images of a patient will be found on the same volume. It is found that alternative B, that when looking at operational performance is preferable, has serious disadvantages over alternative A when recovery and conversion are considered. It seems recommendable to select the simple archive organization A and solve the inherent performance problem by applying a sophisticated system of prefetching. !5