RTCA 218 Processing the Latent Image Bushong Chapter

RTCA 218 Processing the Latent Image Bushong, Chapter 12

Processing the Latent Image Abstract: This section explores the steps in processing exposed radiographic film and digital images. Emphasis will be placed on the chemical agents involved in the development and fixing of the latent image. Included will be a discussion on the components of any automatic processor, alternative processing methods, and components in digital and computed radiography. Objectives: At the end of this section, the student will be able to: n Discuss the development of radiographic film processing. n List and discuss the sequence of processing steps. n List and discuss the chemicals in the developer. n List and discuss the chemicals in the fixer. n Discuss the purpose of the replenishment system. n Discuss the functions of the transport system. n Discuss the functions of the dryer. n List and describe the components of an automatic processor. n Discuss digital processing methods n List and discuss alternative processing methods.

Processing the Latent Image Development of Radiographic Processing Hand Processing vs. Automatic Processing n Wetting – 15 seconds vs. ------n Development – 5 minutes vs. 22 seconds n Stop Bath – 30 seconds vs. ------n Fixing – 15 minutes vs. 22 seconds n Washing – 20 minutes vs. 20 seconds n Drying – 30 minutes vs. 26 seconds

Processing the Latent Image 2. Development n production of the _______ image from the latent image n Mixing developer solution containing sodium hydroxide can be very dangerous —always wear gloves and goggles

Processing the Latent Image n Components of Development 1. Phenidone – reducing agent – produces shades of gray _______ 2. Hydroquinone – reducing agent – produces black tones ________ n Synergism – action of agents working together is greater that the sum of the action of each agent working independently 3. Potassium _______ – restrainer – antifog agent; keeps unexposed crystals from development

Processing the Latent Image 4. Fixing n removal of remaining ____________ from emulsion and hardening of the geletin n Ammonium _______ – fixing agent – removes undeveloped silver bromide from emulsion

Processing the Latent Image n Components of the Automatic Processor Transport System 1. transports film through various stages at precise _______ intervals

Processing the Latent Image 2. roller transport rack n steer film movement n ______ and guide _______ assist film movement and changes in direction

Processing the Latent Image 3. Drive n provide power to turn rollers at precise rate n ________ dimension of the film should be placed against the side rail to maintain proper replenishment rate

Processing the Latent Image n Temperature Control System 1. monitor and adjust temperature of each stage

Processing the Latent Image n n Circulation System 1. ________ fluids Replenishment System 1. Developer and Fixer – replaces solutions; maintains proper _______ and _________

Processing the Latent Image n n Dryer System 1. remove moisture from the film Electrical System 1. provides power to the above systems

Processing the Latent Image n n n Factors affecting film Processing Developer _________ – increase in temp increases density _____ in developer – increase in developer time increases density Developer concentration – increase in concentration increases _______

Processing the Latent Image n Quality Control in Film Processing Artifacts 1. scratches – guideshoes out of alignment 2. _______ Lines – marks precisely 3. 1416 inches apart – nick on 1 -inch rollers

Processing the Latent Image n Roller marks n n Improper position of guideshoes Dirty Rollers Cause emulsion pickup and gelatin buildup n Sludge deposits on film n Result in areas of increase or decreased density n n Wet Pressure Sensitization Caused by dirty rollers in developer n Result in circular patterns of increased density n

Processing the Latent Image n Temperature Fluctuations 1. increased or decreased density – developer _________ 2. damp films – dryer temperature or humid conditions

Processing the Latent Image n Contamination 1. fixer chemicals into developer 2. results in increased _______

Processing the Latent Image n n Jamming 1. rollers out of alignment 2. improper _________ rate – excessive emulsion swelling Startup Procedure

Processing the Latent Image n Cleaning 1. Daily – wash _______ roller, wash tank 2. Weekly – deep rollers, water filters 3. Monthly – chemical tanks, fresh developer and fixer, developer filter

Processing the Latent Image n Sensitometric Testing 1. ensures consistent processing of films 2. performed _______ 3. base + fog – must not fluctuate more than 0. ______ from baseline