IAEA International Atomic Energy Agency Fluoroscopy Radiation Sources in medicine diagnostic Radiology Day 7 – Lecture 1(2)

IAEA 2 Objective To become familiar with of fluoroscopy equipment; To become familiar with specific radiation risks associated with this type of equipment.

IAEA 3 Contents Description of fluoroscopy x-ray systems. Equipment malfunction affecting radiation protection.

IAEA 4 Fluoroscopy is used for the dynamic evaluation of functional disorders and guidance during routine surgical procedures, biopsies, etc. Fluoroscopy is used during interventional radiology procedures. Fluoroscopic equipment uses electronic image intensifiers to provide real-time (dynamic) imaging; Fluoroscopic Equipment

IAEA 5 General purpose fluoroscopic system Fluoroscopic Equipment (cont)

IAEA 6 Mobile fluoroscopic system for routine procedures during surgery Fluoroscopic Equipment (cont)

IAEA 7 shall have an exposure control switch that energises the x-ray tube only when continually pressed (i.e. a dead man control); All fluoroscopic units shall use an image intensifier, and: Fluoroscopic Equipment (cont) should allow the user to choose between continuous or pulsed x-ray generation.

IAEA 8 Fluoroscopic Equipment (cont) Direct fluoroscopy should no longer be used. “Direct” fluoroscopy does not use electronic image amplification. The real-time image is viewed on a fluorescent screen in a completely darkened room and requires the fluoroscopist to dark adapt for approximately 20 minutes before the examination. Improper attention to these requirements can significantly increase the radiation dose to patients and users.

IAEA 9 All fluoroscopic units: shall display the instantaneous values of x-ray tube voltage (kV peak), tube current (mA) and accumulated fluoroscopic exposure time at the control or to the user. The dose rate at the image intensifier input phosphor shall not exceed the relevant IEC recommended values. should be provided with a Dose-Area Product metre or a measuring system to indicate patient exposure. Fluoroscopic Equipment (cont)

IAEA 10 Manual collimation of the fluoroscopic x-ray beam should be possible in addition to automatic collimation and adjusted to (but never greater than) the effective area of the image intensifier. If the fluoroscopic unit is capable of high dose-rate operation a separate visual and / or audible warning shall be provided to the operator. Fluoroscopic systems should incorporate a “last image hold” mode where the last few frames of the fluoroscopic image are displayed as a static image when the fluoroscopic exposure ceases. Fluoroscopic Equipment (cont)

IAEA 11 Malfunctions affecting radiation protection The types of malfunctions that should be considered are: generator and x-ray tube deficiencies listed in previous lectures imaging system problems listed in previous lectures, especially a reduction in image intensifier conversion factor, low efficiency optics, poor resolution and contrast of the image intensifier TV chain;

IAEA 12 Malfunctions affecting radiation protection (cont) inappropriate filtration of the useful x-ray beam; misalignment of the x-ray beam and image intensifier; excessive dose rate (above IEC recommendations) at the image intensifier input phosphor; inadequate or improperly adjusted shielding devices; fluoroscopic exposure timer inaccurate or not functioning; incorrectly calibrated patient dose measuring system.