Objectives: To construct and analyze perceptibility curves (PCs) according to two different approaches. Material and methods: A test object was used to determine the exposures and exposure differences between the total thickness of the test object and details consisting of holes of increasing depth. Two digital systems were employed to predict PCs according to the two different approaches. One approach defined exposures and exposure differences from dose-response functions, including secondary and scattered radiation. The other defined exposure and exposure differences as calculated transmitted radiation flux from the primary beam behind the test object, excluding secondary and scattered radiation. Integrals of the PCs and of the minimum perceptible gray-level differences as functions of background gray levels were calculated. The validity of the different types of PCs was analyzed. Another test object was used to predict observer performance for the two systems. Results: The integrals of PCs obtained according to the above first-mentioned approach and integrals of gray-level differences as functions of background gray level were equal. The same integrals using the second approach were different. The second approach, however, successfully predicted observer performance for the two systems. Conclusions: Only the first-mentioned approach gives PCs that are true representations of psychophysical properties. The second approach may, however, be employed to predict observer performance when different radiographic systems are employed.
All Science Journal Classification (ASJC) codes
- Dentistry (miscellaneous)
- Radiology Nuclear Medicine and imaging