Image compression and chest radiograph interpretation: image perception comparison between uncompressed chest radiographs and chest radiographs stored using 10:1 JPEG compression.

We have assessed the effect of 10:1 lossy (JPEG) compression on six board-certified radiologists' ability to detect three commonly seen abnormalities on chest radiographs. The study radiographs included 150 chest radiographs with one of four diagnoses: normal (n = 101), pulmonary nodule (n = 19), interstitial lung disease (n = 19), and pneumothorax (n = 11). Before compression, these images were printed on laser film and interpreted in a blinded fashion by six radiologists. Following an 8-week interval, the images were reinterpreted on an image display workstation after undergoing 10:1 lossy compression. The results for the compressed images were compared with those of the uncompressed images using receiver operating characteristic (ROC) analyses. For five of six readers, the diagnostic accuracy was higher for the uncompressed images than for the compressed images, but the difference was not significant (P > .1111). Combined readings for the uncompressed images were also more accurate when compared with the compressed images, but this difference was also not significant (P = .1430). The sensitivity, specificity, and accuracy values were 81.5%, 89.2%, and 86.7% for the compressed images, respectively, as compared with 78.9%, 94.5%, and 89.3% for the uncompressed images. There was no correlation between the readers' accuracy and their experience with soft-copy interpretation; the extent of radiographic interpretation experience had no correlation with overall interpretation accuracy. In conclusion, five of six radiologists had a higher diagnostic accuracy when interpreting uncompressed chest radiographs versus the same images modified by 10:1 lossy compression, but this difference was not statistically significant.

A Regional Occupational Medicine Service: Qualitative and Quantitative Assessment.

A quantitative description of a regional occupational medicine system, serving some 200,000 workers in a broad spectrum of occupations, is given. The main activities of the service-pre-employment, medical surveillance, and fitness-to-work examinations-are presented in quantitative terms. Approximately 27,000 examinations are performed annually, of which about 50% require biological monitoring for a specific occupational exposure, 35% are fitness-for-work examinations, and 15% are pre-employment examinations. The main abnormal findings identified by fitness examinations involved the musculoskeletal (25%), cardiovascular (13%), or upper respiratory, pulmonary, and neurologic systems (3% each). Among surveillance examinations, the most frequently identified pathology is phonal trauma (11%). The three types of examinations are looked at with respect to rates of abnormal findings over a one-year period, compared with the mean rate of abnormal findings over the preceding five-year period, and future trends are extrapolated. The implications regarding assessment of resource allocation, appropriate budgeting, and personnel recruitment and training, as well as planning of worker safety and health maintenance programs, are noted. The authors conclude that ongoing quantitative analysis of the activities of a regional occupational medicine service is mandatory for quality assurance and future planning responsive to the dynamic needs of the target workforce.

The therapeutic use of computers in occupational therapy with patients with closed head injuries.

Occupational therapists in various settings were surveyed to obtain information on their use of computers with closed head injured patients. The majority of therapists use micro-computers for cognitive rehabilitation followed by vocational rehabilitation. Respondents indicated that an efficient means of distributing information does not yet exist resulting in a high incidence of trial and error learning on the part of the therapist.