This piece was originally published in the August 2016 issue of electroindustry.
Megan A. Hayes, Director, Regulatory and Standards Strategy, MITA
The Medical Imaging and Technology Alliance (MITA), a division of NEMA, published NEMA XR 31-2016 Standard Attributes on X-ray Equipment for Interventional Procedures in May 2016. This new standard, which pertains to MITA Smart Dose Interventional technology, offers healthcare providers a reference for identifying key features that contribute to enhanced patient care and help manage patient radiation dose delivery, while still enabling the system to provide sufficiently high image quality.
NEMA XR 31-2016 describes eight features that should be taken into consideration when performing risk management evaluations on existing, stationary x-ray interventional equipment. These key features were introduced over the past decade and are now considered state of the art:
- Dosimetric indications: Dose information displayed to the operator during the procedure may increase dose awareness and enable interventionists to monitor the dose to the patient in real time.
- Added filters: Insertion of filters into the x-ray beam aims to reduce the amount of low-energy photons that will not produce an image but can be directly absorbed by the patient’s skin, increasing the risk of adverse reactions.
- Range of air kerma rates in fluoroscopy: The equipment will include at least three selectable dose rates that permit the interventionists to tailor the dose to the imaging task at the lowest dose that matches the complexity of each phase of the interventional procedure.
- Last-image hold (LIH): The most recently acquired image will be displayed after termination of irradiation, thus potentially reducing the need for additional fluoroscopy
- Virtual collimation: The equipment will provide a graphical display of the position of the collimator blades on the LIH image while the collimator blades are adjusted, without irradiation.
- Stored fluoroscopy: The equipment will provide the capability to store at least 300 frames of the most recent fluoroscopic-imaging sequence, allowing for replay and review during the procedure.
- Variable pulsed fluoroscopy: For fluoroscopy, the equipment will provide at least three different pulse rates, selectable by the user. This option will enable the interventionist to tailor the dose to the imaging task. The rate of anatomical motion, the specific imaging task, and the operator’s ability to adapt to lower temporal resolution determine the appropriate pulse rate for each segment of an interventional procedure.
- Digital x-ray imaging device: For almost all dose ranges used in radiography and fluoroscopy, this technology provides a better dose efficiency compared to image intensifier systems.
Each of the attributes described in XR 31-2016 is intended to offer an additional way to manage the radiation dose, thus leaving one more degree of freedom to the physician to reduce the patient dose, when appropriate, and minimize the risk of tissue reaction that may arise during prolonged interventional procedures.
XR 31-2016 is available as a complimentary download on the NEMA Standards Store.