Operator Should Stand at Least 6 Feet Away from Patient to Reduce Radiation Exposure to the Operator. By Hiba Al-Shawa / March 29, 2022 Back to: INBDE Oral Radiology Mnemonics Previous Lesson Diameter of Circular Beam at Patients Face: Maximum 2.75 inch Lesson 1 within section Oral Radiology Mnemonics. You must enroll in this course to access course content. Next Lesson Ekta-Speed Film is the Most Effective Way to Reduce Exposure Time, Amount of Radiation Reaching the Patient and Scatter Radiation Lesson 3 within section Oral Radiology Mnemonics. You must enroll in this course to access course content.