Fluoroscopy: Static Image Recording Systems

Static Recording Systems Static images are necessary when a permanent record of the fluoroscopic examination is required Static recording is done using: Video discs Spot film cameras Conventional cassettes Digital fluorography

Video disc recorders used to record: Video Disc Recording Video disc recorders used to record: Single field Single frame Short sequence Last image hold / freeze or “sticky fluoroscopy” Electronic radiography Frame rates or speeds vary from 1 image per sec to 30 images per second Both magnetic and laser video disc equipment is available for either digital or analog recording

Spot Filming Spot filming is accomplished using: Spot filming can be performed in a manner that functions as a single image or a series of images simulating a dynamic recording (serial spot films) Spot filming is accomplished using: 100 or 105 mm chip film (cut film, sheet film) 70 or 100 mm roll film (long roll of film) Cassettes (film/screen & imaging plate)

Spot Filming - Roll, Chip, Cut or Sheet film Photospot or spot film cameras photograph image on output phosphor of image intensifier Typically use much higher mA with short exposure time to acquire image as compared to simple fluoroscopy Functionally much slower Like sheet film used in conventional radiography, cut and roll film requires wet chemical processing Photo spot camera close in design to cine camera 20 – 50 times higher dose per frame than fluoro Still a substantial dose reduction compared to cassette spot film (about 50% reduction per image) If serial photospots are taken, dose will increase

Camera removed from light distribution center of image intensifier 105 mm Roll Film Camera TV Camera 70mm camera supply and take-up magazine 70mm camera Light distribution center Image intensifier Camera removed from light distribution center of image intensifier

UGI Series using 105 mm roll film 105 mm Roll Film Camera Roll film supply magazine removed from photospot camera Roll film removed from supply magazine UGI Series using 105 mm roll film Images are cut into strips of 4 and laminated together for ease of handling

105 mm Roll Film 105 mm Roll film showing UGI and BE Photospot images. An optical “Overframe” method was used to project the image onto the film

Chip or Sheet Film Changers Chip film changers use individual sheets of 100 or 105 mm film contained in a magazine Operationally, the camera works nearly identical to a roll film changer with the exception of a mechanical device to handle sheet film An exposed film receiver stores the images prior to wet chemical film processing of individual sheets

Cassette Spot Filming Standard sizes include: product-image.tradeindia.com Uses standard radiographic cassettes Utilizes remnant (pre-intensified) exiting radiation from patient Standard sizes include: 9” x 9” (24 x 24 cm) 8” x 10” (18 x 24 cm) 10” x 12” (24 x 30 cm) Other spot film changers will take 11” x 14” and 14” x 17”

Cassette Recording – How it Works Cassette is stored in lead-lined compartment in fluoro carriage Controls on fluoro carriage initiate mechanism for spot film exposure Carriage controls permit selection of different areas of cassette to be exposed After exposure is initiated, AEC terminates exposure at set density Cassette is transported to intercept primary transmitted x-ray beam X-ray tube current boosted to 100-1,200 mA 1on1 2on1 3on1 4on1 etc. Collimator shutters and spot film mask shutters automatically mask to desired area of exposure Cassette auto centered on area to be exposed Cassette is returned to “park” position in storage compartment

Cassette Recording Cassette spot filming causes single highest dose rate of all fluoro recording mediums May require up to 300µR per exposure at the cassette Translates into over 30 mR entrance skin exposure (ESE) Estimated that each spot film may be equal to more than one minute of fluoroscopic time Significant tendency to over-document negative findings in the U.S. due to malpractice litigation

Digital Fluoroscopy Digital (computerized) fluoroscopy produced images using video camera and digital image processor Image converted by analog-to-digital (ADC) converter This step can be eliminated if using a digital video camera (CCD) Digital data computer processed and stored in image processor memory Image must be converted back to an analog image by a digital-to-analog (DAC) converter to view Currently, PACS systems can be used for digital image storage

High Level or “Boost” Fluoroscopy Boost fluoroscopy refers to a “special activation” capability of certain fluoroscopy systems Entrance dose rate to patient is 2-10 times greater than conventional fluoroscopy May result in total patient dose rates exceeding several hundred rads Interventional radiology and cardiac procedures can be long and demanding Extremely small guidewires and catheters must be visualized Requires High signal-to-noise ratio Very low quantum mottle

Key Points Regarding Boost Special activation at the control panel is required with an additional person Key and interlock must be activated Audible signal must be heard in the room while high level or boost fluoroscopy is energized In 1994, regulations were passed limiting maximum tabletop dose rate to 20 rads per minute when acquiring images without recording devices are being utilized

Just so you know… Department of Health and Human Services Centers for disease and Control and Prevention Cutaneous Radiation Injury: Fact Sheet for Physicians Acute Radiation Syndrome: Fact Sheet for Physicians

Please close this PowerPoint presentation, and continue the lesson. What’s Next? Please close this PowerPoint presentation, and continue the lesson. Presented by Based on: Principles of Radiographic Imaging, 4th Ed. By: R. Carlton & A. Adler Radiologic Science for Technologists, 8th Ed. By: S. Bushong Syllabus on Fluoroscopy Radiation Protection, 6th Rev. By: Radiologic Health Branch – Certification Unit