Interpretation, Image Quality and Faults 2024 PDF

Interpretation, image quality and faults Georgina Catlow BVSc MRCVS Learning objectives To be able to describe a radiographic image in terms of quality, radiographic positioning and adequacy of exposure in relation to the tissues of interest To describe potential imaging faults and the mean...

Interpretation, image quality and faults Georgina Catlow BVSc MRCVS Learning objectives To be able to describe a radiographic image in terms of quality, radiographic positioning and adequacy of exposure in relation to the tissues of interest To describe potential imaging faults and the means to avoid, identify and account for them To discuss the relative advantages and disadvantages of digital and film radiography with regard to image faults #universityofsurrey 2 Simplified Radiographic Report Description Radiographic Diagnosis Differential Diagnosis Recommendations Patient name Description of image Prioritise list Further recommendations Signalment Most significant Imaging History Incidental findings Surgery Diagnostics Area imaged Identify variations from Ongoing management Projections normal Quality Summary of findings Exposure Positioning Technical faults #universityofsurrey 3 How do I remember what to comment on??? P: Positioning C: Centering C: Collimation E: Exposure L: Labelling A: Artefacts ‘Pink Camels Collect Extra Large Apples’ #universityofsurrey 4 Area Imaged / Positioning Name area of interest The area of interest will determine projections required Minimising non-pathological variation Standard views Standard positioning Standard exposure settings #universityofsurrey 5 Radiographic Projections Named according to the direction the primary beam penetrates the body part (from point of entrance to point of exit) Lateral radiographs are named by the side in which the patient is lying on #universityofsurrey 6 Patient positioning Principles of radiographic positioning Minimising geometric distortion Magnification Orthogonal views Centering #universityofsurrey 7 Geometric distortion #universityofsurrey Images courtesy of BSAVA manual of radiography and radiology 8  Object-focus distance #universityofsurrey Magnification object Focal Spot Object-film distance Film-Focal distance Object-film distance object Focal Spot Object-focus distance 9 Orthogonal views Always take orthogonal views to identify abnormalities in ‘3D’ #universityofsurrey 10 Centering Centre to the anatomical area of interest using bony landmarks Allows close collimation to avoid scatter Centring corresponds with the cross on the light diaphragm when the collimator light is switched on #universityofsurrey 11 Collimation Accurate collimation reduces radiation dose, scatter and improves contrast and image quality Bisgaard et al Front.Vet.Sci.14 Dec 2021 #universityofsurrey 12 Exposure #universityofsurrey 13 Exposure Film/Screen Digital Too dark Quantum mottle Over exposed Under exposure (Over developed) ‘grainy’ appearance Too white Under exposed Under developed #universityofsurrey 14 Exposure Under exposed – increase KV Over exposed – decrease KV #universityofsurrey 15 Labelling Radiographs should be labelled with: L / R marker Marker should be visible on image Should not be underneath a body part Can be added electronically on digital images Dental radiography often uses a dot on the film to indicate side Patient name/date often not directly on image in digital systems Other labelling requirements exist for canine health schemes (elbow and hip) #universityofsurrey 16 Viewing a radiograph Lateral views o Rostral part of animal to viewer’s LEFT Ventrodorsal/Dorsoventral o Rostral part of animal pointing UP and LEFT of animal to viewer’s RIGHT Lateromedial/mediolateral extremities o Proximal limb UP o Cranial/dorsal limb to viewer’s LEFT Craniocaudal/Caudocranial extremities o Lateral aspect limb to viewer’s LEFT #universityofsurrey 17 Image orientation –which is correct? #universityofsurrey 18 Image orientation – which is correct? #universityofsurrey 19 Quality – Artefacts Common to digital and film/screen radiography Incorrect/no labelling (name, date, L/R marker) Poor positioning Poor collimation Movement blur Fogging Double exposure Radiopaque artefacts on the patient (mud, wet coat, syringe under patient!) #universityofsurrey 20 Fogging and Scatter radiation Focal Spot Scatter causes random blackening of the image Reduced by o Using grids Patient o Appropriate collimation Grids o Use if tissue is over 10cm Grid o Placed between the cassette and Black = lead patient White = plastic o Placed on top or under table in DR system Film #universityofsurrey 21 Film/Screen Faults Over exposed Fogging Over developed Incorrect storage Fogging Old film Under developed Under exposed Poor washing of fixer Under developed Prolonged storage #universityofsurrey 22 Digital Faults Post exposure faults Partial erasure of image and fading White specks and lines Moire artefact Workstation faults Incorrect algorithm Incorrect cropping Uberschwinger artefact #universityofsurrey Images courtesy of BSAVA manual of radiography and radiology 23  Description of the image #universityofsurrey 24 Röentgen signs Roentgen signs Change Possible cause Size Increased Hypertrophy, hyperplasia, neoplasia, torsion, cystic change Decreased Atrophy, hypoplasia, congenital anomaly Shape Localised or diffuse Neoplasia, necrosis, ulceration Number Increased Accessory ossification centre, congenital anomaly Decreased Congenital anomaly Position Displacement Torsion, ectopia, hernia Opacity Increased Calculi, mineralisation, fluid/ST in a gas filled structure Decreased Abnormal gas, osteopenia Margination Periosteal reaction, protruding mass, surrounding fluid/gas #universityofsurrey 25 Opacity Radiolucent Radiopaque #universityofsurrey Image courtesy of Thrall. Textbook of Veterinary Diagnostic Radiology 26 Tell me about opacities…… #universityofsurrey 27 Border effacement Also known as Silhouette Sign Two structures of same opacity are in contact Cannot distinguish margins of two structures Pathological causes Right middle lobe pneumonia Pleural effusion Peritoneal effusion #universityofsurrey Image courtesy of Thrall. Textbook of Veterinary Diagnostic Radiology 28 Finishing the report Identify abnormalities Summarise findings Consider differentials Things to avoid o DAMNITV Bias Satisfaction of search Further diagnostics #universityofsurrey 29 Let’s have a go……. P C C E L A #universityofsurrey 30 31