Retake analysis 2.pptx

z By Dr. Mohsen Dashti 481 Quality Assurance Retake Analysis 2 z Introduction  Retake analysis: A systemic process of cataloguing rejected films and determining the nature of the repeated images so it can be minimised or eliminated. HSC 3 z Features  Retake analysis provides important...

z By Dr. Mohsen Dashti 481 Quality Assurance Retake Analysis 2 z Introduction  Retake analysis: A systemic process of cataloguing rejected films and determining the nature of the repeated images so it can be minimised or eliminated. HSC 3 z Features  Retake analysis provides important data: 1. Accessory performance 2. Departmental procedures 3. The skill level of the technical staff. HSC 4 z Advantages 1. Save departmental costs 2. Save patient dose 3. Reduce department repeat rate ( reduce patient time undergoing diagnostic procedure). HSC 5 z Causal repeat rate  To investigate the cause of the repeat rate, a worksheet should be included in the department to obtain a large statistical sample (at least 250 patients) for reliability. HSC Causal repeat rate  The repeating rate governed by the following equation: Casual repeat rate  Number of repeat for a specific cause 100 Total number of repeats HSC 6 Causal repeat rate  To investigate the total department repeat rate, the following equation is used: Number of repeat films Total repeat rate  100 Total number of views taken  Department repeat rate should not exceed 4-6% and should be less than 2% of mammo. procedures. HSC 7 8 z Causal repeat rate  Any department exceeding 10-12% should be examined seriously, cause departments contribute to a high patient dose. are inefficient and HSC 9 z Artefacts analysis  Artefacts: anything on a finished radiograph that is not a part of the patient’s anatomy.  Categories: 1. Processing artefacts, 2. Exposure artefacts, 3. Storage and handling artefacts. HSC 10 z I. Processing artifacts  Occurs during processing of the image, may include: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. Gelatin build up 11. Water spots Curtain effect 12. Wet pressure sensitization Chemical fog13. Hypo retention Guide shoe marks 14. Insufficient OD Pi lines 15. Excessive OD Chatters Dichroic stain Reticulation marks Streaking Hesitation marks HSC 11 z 1. Gelatin build up  Emulsion removed from earlier films (either stuck on processor rollers or dissolved in the developer solution) deposited on the film.  Solution:  under replenished developer solution.  failure of the developer circulation system filter. HSC 12 z 2. Curtain artifacts • Patterns on the film that resemble a lace curtain. • Solution dripping on, or “running down” a film. • Causes: HSC 1. Common in manually proccesing. 2. Wash water is dirty in automatic processor 13 z 3. Chemical fog An overdevelopment of the film result in excessive base + fog and minimum diameter (Dmin) values with sensitometry films. Causes: Change in developer temperature, time, pH, or concentration or overreplenishment of the developer solution. HSC 14 z 7. Dichroic (Two colours) stain  Brown stains:  Cause:  Film processed in oxidized developer or hyporetention present during several years of storage.  Greenish stain:  Resemble:  Presence of unexposed and undeveloped silver halide crystal remaining on the film after processing (incomplete fixation) HSC 15 z 10. Hesitation marks (stub lines) Stripes of density. Cause: decreased optical Transport roller are left in contact with the film and further development is prevented when; – Processor is turned off or loses power while the film in the developer section. – Film jammed while in the developer section. – Transport system speed decreases significantly. HSC 16 z 11. Water spots Pattern of increased optical density appears after processing. Cause: Water or other liquid come in contact with an un-processed image. HSC 17 z 13. Hyporetention White, powdery residue on the film surface because of incomplete washing (fixer chemicals crystallized as the film dries) Cause: 1. Lesser degree of hyporetention can result in brown dichroic stains HSC 18 Processing artifacts z Lack optical density (result from developer ). 1. Temperature below acceptance limits. 2. Time is insufficient. 3. Solution that replenished. 4. Contaminated by the fixer. 5. PH that is too low. 6. Concentration that is insufficient. is under- Excessive optical density (result from developer). 1. Temperature’s exceed the accepted limits. 2. Excessive time. 3. Over-replenishment 4. Higher accepted limits pH 5. Excessive concentration HSC 19 z II. Exposure artifacts  Caused by the patient, the technologist, or the equipment during a diagnostic procedure. HSC 20 z II. Exposure artifacts 1. Motion artifacts 2. Heat blur 3. Patient’s artifacts 4. Improper OD 5. Improper patient positioning or missing ROI 6. Quantum mottle 7. Poor f/s contact 8. Double exposure 9. Grid artifacts 10. Grid cut-off 11. Moiré effect (Zebra artifacts) HSC 21 z Motion and heat blur 1. 2. Motion blur:  Motion of the patient, x-ray source, or image receptor.  Reduced with short exposure time, immobilization, and proper instructions to the patient. Heat blur:  Computerized radiography (CR) system imaging plate is exposed to intense heat before being processed within the CR reader system. HSC 22 z 3. Patient artifacts  Caused by items (e.g., buttons, snaps, necklaces, earning, hairpins, wet hair, and body piercing jewelry) either on or within the patient when a diagnostic procedure is performed. HSC 23 z 4. Improper optical density  Improper selection of technical factors or cell selection with AEC by the technologist.  Histogram error in CR, an incorrect preprocessing histogram is selected (such as an adult histogram for the radiography of pediatric chest).  Nonparallel collimation , for the histogram used by CR system to process the final image the collimation edges of the radiation field should be parallel to the sides of the imaging plate. HSC 24 z 5. Miss positioning or loss of ROI  Improper patient, X-ray, or image receptor positioning by the technologist or improper collimation, which can clip the anatomy of interest. HSC 25 z 7. Poor film-to-screen contact  localized blurring of radiographic image and slightly increased optical density in these regions. HSC 26 z 8. Double exposure  Image receptor is exposed more than one before the image is exposed. HSC 27 z 9. Grid artifacts Improper use of grid causes grid artifacts Grid lines: shadows of the lead strips, causes: Failure of the grid to move during the exposure Improper grid-focusing distance Improper angulations of the central ray with aspect to the grid lines Improper centering. HSC 28 z 11. Grid cut-off Decrease in optical density caused by primary radiation being absorbed by (or cut off by) the grid. Cause: – Any improper use of grid can cause grid cutoff. HSC 29 z 12. Moiré (zebra) artifacts A double set of grid lines Cause: – Placement of a grid cassette in a bucky. HSC 30 z III. Handling and storage artifacts  Occurs during darkroom handling or during storage before use HSC 31 z III. Handling and storage artifacts Light fog Age fog Safe light fog Radiation for Pressure marks Static marks: 1. 2. 3. 4. 5. 6. 1. 2. 3. 7. 8. 9. Tree static Crown static Smudge static Crescent or crinkle marks Scratches Cassette marks HSC 32 z 1+2. Light and age fog 1. Light fog  Fog, is any non-informational optical density present in a film image.  Light of any improper color that strikes the film before development fogs the film  lowers the image contrast. 2. Age fog  Occur in film processed beyond the expiration date or stored in a warm, humid environment.  lower image contrast. HSC 33 z 3+4. Safelight and radiation fog 3. Safelight fog  Causes: 1. improper safelight filter, 2. cracks, or 3. pinholes in the safelight filter, 4. incorrect wattage of the safe light bulb, 5. incorrect distance between the safelight and work surfaces, or 6. widely open sodium vapor lamp shutters. 4. Radiation fog  Film exposed to ionizing radiation before development. HSC 34 z 6. Static Sparks from static electricity, 1. Tree static: the static resemble trees or bushes without leaves. low humidity condition in the film processing area. 2. Crown static: marks radiate in one direction. excessive friction from the pulling of the film. 3. Smudge static: dark areas rough handling in the film processing area. HSC 35 z 7. Crescent marks Half-moon-shaped marks of increased optical density caused by bending of the film unprocessed. decrease optical density caused by bending of a processed film image. HSC 36 z 8. Scratches  Areas of removed emulsion by sharp objects, such as fingernails or sharp points on surfaces. HSC 37 z 9. Cassette marks White specks on the image caused by dirt or debris that is inside the cassette. Foreign matter blocks the light from the screen from reaching the film. HSC 38 z Accuracy, sensitivity, and specificity  Main outcome of diagnostic imaging examination are: a) Accurate diagnosis, b) Sensitivity of system to diagnose positive cases c) Specificity of system to obtain patients with no disease HSC Accuracy  It is a percentage of cases that is diagnosed correctly. HSC 39 Sensitivity  referred to as TP fraction and indicates the likelihood of obtaining a positive diagnosis in a patient with the disease HSC 40 Specificity  known as the TN fraction and indicates the likelihood of a patient obtaining a negative diagnosis when no disease is present HSC 41 42 z Accuracy, sensitivity, and specificity  The ideal for all the values is 100%. diagnostic imaging department is responsible for establishing its own threshold of acceptability for each value. HSC 43 z References 1. Jeffrey Papp. Quality Management in the imaging Sciences (2002). 2nd edition. 2. www.appliedradiology.com HSC