The effect of a picture archiving and communication system (PACS) on patient radiation doses for examination of the lateral lumbar spine.

This study was conducted to determine whether the doses for the radiographic examination of the lateral lumbar spine changed as a result of the introduction of a hospital-wide picture archiving and communication system (PACS). Doses were measured by thermoluminescent dosimeters (TLD) and dose-area product (DAP) meter readings for 100 patient examinations using a 300-speed conventional film/screen system and for 96 patient examinations when PACS was fully operational. Radiographic technique, exposure factors and patient characteristics were noted and effective doses were calculated, and a comparison was made of all variables. No significant differences between conventional and PACS working were found in surface entry and effective doses for single views of the lateral lumbar spine, but there was a 20% reduction in DAP readings with PACS. However, when summed doses for all images, including rejects, required to demonstrate the lateral lumbar spine for each patient were compared, PACS was found to be associated with significantly lower surface entry (TLD) dose, DAP reading and effective dose (28%, 36% and 16%, respectively) than conventional film. For single images of L1-5, when PACS was in use, there was a significant reduction in the DAP readings and increases in the area of the film/plate irradiated, the focus-to-skin distance and the focus-to-film distance. In addition, significantly fewer lumbosacral junction views were undertaken when PACS was in use. Since many confounding factors may have influenced the results over the period of dose measurement, regression models were used to determine the significance of PACS. These models showed that the use of PACS was not significant in causing any differences in the dose for single images as compared with when film was used, but was significant in the resulting total dose reductions for the examinations.

Comparison of film, hard copy computed radiography (CR) and soft copy picture archiving and communication (PACS) systems using a contrast detail test object.

This paper describes two experiments where a widely available test object (FAXIL TO20) was used to compare film, hard copy computed radiography (CR) and soft copy picture archiving and communication systems (PACS) images. Baseline images were produced with a fixed mAs. All images were scored by four experienced medical physicists. Contrast detail curves for the three types of images were almost identical. A second series of images was produced with the mAs varying from 1 mAs to 250 mAs. The contrast detail curves were plotted for each mAs value and the wider exposure latitude of CR compared with film was demonstrated. Use of PACS provided no further increase in exposure latitude. The density of the film images increased with mAs but the density of the CR hard copy images remained constant. It is of concern that the wider latitude of the CR images extends to exposures that are much higher than those used for film with no noticeable change in CR image density but with better images at higher exposures, because the potential exists for patient doses to increase. Hard copy CR images provide information about the exposure index which relates to the input dose to the plate and hence approximately to the dose to the patient. However, since such information is currently not available on default soft copy images, the authors suggest that all manufacturers of PACS should provide an indication of dose as a mandatory default setting.

A comparison of image reject rates when using film, hard copy computed radiography and soft copy images on picture archiving and communication systems (PACS) workstations.

A comparison has been made of the reject rates of plain images for three separate periods when film, computed radiography (CR) and PACS systems were in operation throughout the Hammersmith Hospital, London. There was a statistically significant reduction in the overall percentage reject rate across all examinations from 9.9% to 8.1% when the hospital changed from using a conventional film based system to a CR system. There was a further reduction in the reject rate to 7.3% when the hospital moved to a hospital-wide PACS system, but this change was not statistically significant. Using estimations of the total number of images used, the percentage reject rates were 6.6% for film, 5.5% for CR and 5.5% for PACS. Thus, if the radiation dose for each image is unchanged, and the same types of images are used for the examination of each body area, a move from conventional film imaging to phosphor plate imaging provides the potential to reduce the patient population dose.

The benefits of hospital-wide picture archiving and communication systems: a survey of clinical users of radiology services.

This paper describes one element of a broad evaluation of a hospital-wide picture archiving and communication system (PACS): an assessment of the views of users of the radiology service, their major causes of dissatisfaction with the service, the incidence of image unavailability, and the consequences of images being unavailable. The principal research design was a "before and after" comparison at Hammersmith Hospital, as the hospital site introducing PACS. Several other hospitals were included in this survey, for comparison. Questionnaires were distributed several times before PACS was operational at Hammersmith, and on one occasion after. The overall response rate was 54%. The main pre-PACS radiology-related problem areas were: the non-availability of images, the non-availability of written reports when clinically required, and the time devoted by junior staff to image searching. PACS greatly reduced the perceived problem of image non-availability. But Hammersmith's problems with the availability of radiological reports still remained when PACS was operational. The time junior doctors spent in image-searching was dramatically reduced by the introduction of PACS.

Reducing radiation doses to the breast, thyroid and gonads during diagnostic radiography.

The skin entry and exit doses on patients undergoing routine radiographic examinations of areas in which the breast, thyroid and gonads are included in the primary beam were measured using thermoluminescent dosimeters. To obtain further information about patient doses, measurements were also made on a phantom at similar skin positions and at the positions of these organs. Comparisons of the doses to these radiosensitive organs were made for the antero-posterior and postero-anterior projections. In cases where it was found that the doses were reduced by the use of non-conventional relationship between the relative positions of the patient and the film, suggestions are made for the adaptations which would have to be made to X-ray equipment to enable these projections to be taken routinely. Other techniques, such as air gap techniques and thyroid shielding, whereby patient doses can be reduced during routine radiography are also examined. Finally the implications of these results for radiation protection of patients are considered.

The effect of PACS on the visualization of the lateral cervical spine and the management of patients presenting with trauma.

In patients presenting with trauma, early diagnosis of neck injuries is likely to affect long-term outcome. This paper reports a study that compared lateral images of the cervical spine produced by a Picture Archiving and Communication System (PACS) with the same images produced using computed radiography (CR). The study was undertaken at the Hammersmith Hospital, London. Data were collected on 100 patients who presented with trauma. Both soft copy (PACS) and hard copy (CR) images of the cervical spine were produced for each patient from the same radiographic exposure. The images were viewed by five clinical members of the Accident and Emergency Department. Data were collected on the level of the cervical spine that could be viewed, the clinical management following the viewing of the image and the use of PACS 'tools'. Overall no statistically significant differences between modalities were found in the level of visualization. Within viewer differences were found for three viewers: one indicating better visualization with PACS and two indicating better visualization with CR. The results relating to patient management indicate greater clinician confidence following the viewing of PACS images for two viewers. The use of PACS 'tools' improved visualization of the cervical spine for one viewer.

Comparison of doses for bedside examinations of the chest with conventional screen-film and computed radiography: results of a randomized controlled trial.

PURPOSE: To compare the radiation doses received by patients during bedside chest radiography when a computed radiography system was used and when a 400-speed screen-film system was used. MATERIALS AND METHODS: A randomized controlled trial was performed whereby all patients who were admitted to an intensive care unit were randomly assigned at admission to have all radiographic chest images obtained with either computed or conventional screen-film radiography. Doses were measured for 1 year, during which 269 patients underwent imaging. For these patients, surface entry doses were measured by means of individual thermoluminescent dosimeters placed on the skin at the center of the radiation beam. In addition, data were collected relating to the patient and examination characteristics, as well as to repeat examinations. Effective doses were calculated. RESULTS: The patients in the two arms of the study were well matched. The surface entry doses were higher in the computed radiography group (median, 0.21 mGy for computed radiography and 0.16 mGy for conventional radiography), and the effective doses were also higher (median, 0.036 mSv for computed radiography and 0.027 mSv for conventional radiography). Fewer examinations were repeated when computed radiography was used. CONCLUSION: When computed radiography was used, patient doses increased. The speed of this computed radiography system, which uses phosphor plate imaging, equates approximately to a 300-speed screen-film system.