American Registry of Radiologic Technologists (ARRT) Practice Exam

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Become a certified radiologic technologist by preparing for the ARRT exam. Use flashcards and multiple-choice questions, complete with hints and explanations, to get exam-ready!

Each practice test/flash card set has 50 randomly selected questions from a bank of over 500. You'll get a new set of questions each time!

Practice this question and more.

For a change to 3-phase and 12-pulse, what fraction of the original mAs is recommended?

The correct answer is: 1/2

When transitioning from a single-phase to a three-phase, 12-pulse system, a reduction in milliampere-seconds (mAs) is often recommended due to the increased efficiency and output of the three-phase system. The primary reason for this adjustment is that three-phase systems deliver more consistent and higher output in terms of x-ray beam intensity than single-phase systems. In practical terms, a three-phase, 12-pulse system can produce approximately 1.5 times the radiation output compared to a single-phase system for the same exposure settings. Because of this enhanced output, it is common practice to decrease the required mAs when utilizing a three-phase system to avoid overexposure of the patient. This leads to the recommendation of using about half (or 1/2) of the original mAs setting. This aligns with the answer provided, which suggests halving the mAs is a typical adjustment. This ensures that patients receive an adequate dose without being overexposed, while still obtaining sufficient image quality.