ARRT Registry Practice Test 1

ARRT Registry Practice Test 1 All of the following EXCEPT ___ will result in an increase in AEC response time. a. decreasing the kVp b. Increasing the focal spot size c. increasing the part thickness d. increasing the SID - ANSWER b. increasing the focal spot size Increasing the focal spot size does not change the AEC response time It affects the spatial resolution. Decreasing the kVp increases the exposure time because more photons are absorbed, resulting in fewer reaching the cell(s). The same is true for increasing part thickness. Increasing the SID results in a longer exposure time because of beam divergence and the decrease in the number of photons reaching the cell(s). Of the following, the greatest attenuator of x-rays is: a. air b. bone c. muscle d. fat - ANSWER b. bone Air allows for the greatest transmission of x-rays. The probability of bone and soft tissue (muscle, fat) attenuating x-rays via Compton interactions is roughly the same. However, since bone has a higher effective atomic number than soft tissue, bone attenuates more x-rays via photoelectric interactions. The ______ sinus(es) sit(s) directly beneath the sella turcica. a. ethmoidal b. frontal c. maxillary d. sphenoidal - ANSWER d. sphenoidal The sphenoidal sinuses are usually paired (2) and are in the body of the sphenoid bone. The sinuses lie below the sella turcica and extend between the posterior ethmoidal air cells and the dorsal sellae