PubMed · 10146481
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M E Bernardino. 1993. Spiral methods create some practical problems.. https://pubmed.ncbi.nlm.nih.gov/10146481/
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The most successful digital radiography detectors to date have been storage phosphor plates used in computed radiography (CR). The detector is cheap, has good producibility, and is robust. Direct radiography (DR) systems are being developed based on flat-panel technology. Better image quality is claimed for some DR systems. On the other hand, DR detectors have low producibility and robustness, and a high price. A new CR detector is being developed at Agfa that combines the advantages of CR and DR. It is a storage phosphor plate made up of needle-shaped crystals. The phosphor efficiently converts absorbed x-ray quanta into photostimulable centers for efficient read out. It has a large dynamic range and its emission is efficiently detected with both photomultiplier tube (PMT) and charge coupled device (CCD). It is shown that CR systems based on the new detector offer image quality that matches that of the best DR systems.
The purpose of this communication is to report on the testing of the disaster recovery capability of our hierarchical storage management (HSM) system. Disaster recovery implementation is a requirement of every mission-critical information technology project. Picture archiving and communications systems (PACS) certainly falls into this category, even though the counterpart, conventional film archive, has no protection against fire, for example. We have implemented a method for hierarchical storage with wavelet technology that maximizes on-site case storage (using lossy compression), retains bit-preserved image data for legal purposes, provides an off-site backup (lossless bit-preserving wavelet transform), and provides for disaster recovery. Recovery from a natural (earthquake and subsequent fire) or technical (system crash and data loss) disaster was simulated by attempting to restore from the off-site image and database backup to clean core PACS components. The only existing loaded software was the operating system. The database application was reloaded locally, and then the database contents and image store were loaded from the off-site component of the HSM system. The following measurements were analyzed: (1) the ability to recover all data; (2) the integrity of the recovered database and image data; (3) the time to recover the database relative to the number of studies and age of the archive, as well as bandwidth between the local and remote site; and (4) the time to recover image data relative to compression ratio, number of studies, number of images, and time depth of the archive. This HSM system, which maximizes on-site storage, maintains a legal record, and provides off-site backup, also facilitates disaster recovery for a PACS.
In the replacement of both a radiology information system (RIS) and a picture archiving and communication system (PACS) archive, data were migrated from the prior system to the new system. We report on the process, the time and resources required, and the fidelity of data transfer. We find that for two PACS archives, both organized according to the Digital Imaging and Communications in Medicine (DICOM) information model, data may be transferred with full fidelity, but the time required for transfer is significant. Transfer from off-line backup media was found to be faster than transfer from our robotic tape library. In contrast, the RIS replacement required extensive labor to translate prior data between dissimilar information models, and some data were inevitably lost in the translation. Standards for RIS information models are needed to promote the migration of data without loss of content.