Radiation Dose Reduction Using Advanced Fluoroscopy Options in Coronary Cath Lab

Fluoroscopy is integral part of diagnostic and therapeutic cardiac procedures. Due to the ionizing effect of X-rays; patients, interventionist and cath lab staff are at risk of radiation hazards that are broadly divided into two categories. One is deterministic; where severity of the injury to the exposed area is dose dependent and there is a safety threshold; the other is stochastic or probabilistic where any radiation dose can cause genetic mutation and cancers and no dose is considered safe. Among medical personnel, interventional cardiologists have the highest per head per year exposure to ionizing radiation which is two to three times greater than the radiologists. Although the patients' exposure is well below the level associated with increased cancer risk, yet as mentioned above, any exposure can be harmful and must be minimized using all possible dose reduction methods under the principle of 'As Low as Reasonably Achievable' (ALARA).

Radiation exposure is influenced by factors that are dependent on patient (weight, body habitus), procedure (access site, procedure complexity, use of protective shielding, collimation) and equipment (overall quality control, field of view, beam filters thickness, pulse rate etc.). In fact in modern fluoroscopic equipment, several settings are customizable to aid reduce total emitted X-ray dose. A lower frame rate of 7.5 frames per second (fps) compared with standard 15fps substantially reduces X-ray exposure (30% relative exposure reduction in operator dose and 19% in patient dose) without compromise in image quality. Using live zoom to digitally enlarge images also lowers the dose by 40-50% (1.4 factors with 6 inch field of view). Another significant advancement is 'Dose Tracking System' (DTS) which calculates the precise radiation dose to the patient's skin and displays the cumulative dose values as a color map on a patient graphic for immediate feedback to the interventionist. This knowledge of the exposure in real time too helps physicians adjust their practices accordingly.

In a diverse coronary lab as Tabba Heart institute, in addition to training the lab staff on reducing radiation exposure and use of protective gear, employment of a modern X ray system Like Toshiba (Infinix i8000V, Toshiba America Medical Systems, Inc.); equipped with customizable radiation dose reduction technologies and DTS, provides the interventionists an essential tools to ensure the highest radiation safety standards. Data is still scanty to show the difference in patients and operators' radiation exposures by using tailored equipment settings. We aim to apply customized fluoroscopy protocols based on low fps and other customizable settings (thickness of the spectral beam filters, peak tube voltage and peak cathode current, live zoom (1.4 factors with 12 inch FOV), fluoro store and Spot fluoroscopy) and then assess if they significantly affect the radiation exposure of the patient and the interventionist.

AIMS/OBJECTIVES

1. To compare the effect of three different fluoroscopy protocols on patient and operator's total X ray dose in coronary catheterization lab at Tabba Heart Institute, Karachi.
2. To assess the effect of low frames per seconds settings in cine imaging and fluoroscopy on quality of image during coronary procedures METHODS