RATIONALE AND OBJECTIVES
Mammography providers are under increasing pressure to become certified by the American College of Radiology (ACR). Successful accreditation is contingent on passing a phantom image quality test. This study was undertaken to evaluate viewer performance with the phantom image evaluation process and to determine any observer group differences.
A series of standard phantom images were viewed by 30 medical physicists, 30 diagnostic radiologists, and 30 inexperienced observers. From the responses, object detection rates and passing rates according to the ACR criteria were established. These responses were analyzed with standard nonparametric tests to assess the degree of variability, correlation, and agreement among different observer groups.
Median passing scores were similar for the radiologists and untrained readers, but the medical physicists appear to differ from the other two groups. There was not sufficient evidence to indicate that special training among physicists made a significant difference in median passing scores or mass detection rates. However, such training appeared to significantly affect the detection of microcalcification and fibril test patterns among the physicists' subgroups. Agreement among observer groups was high for all groups, but tended to be lower for overall passing rates than for any of the individual test objects. Agreement among physicists was affected by their subspecialty, presumably caused by their levels of specific training for these visual tasks.
The authors conclude that choosing medical physicists to evaluate mammographic phantom films appears to be a good choice among potential observer groups, and that special training for reading these images affects their detection abilities and consistency. However, because passing rates did not appear to be affected by special training and given the current rapid degree of change in this area, more testing of medical physicists is desirable to examine these effects over time, and to study the effect of developing standards for training.
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