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Advanced Diagnostic Imaging Studies. Theatre Imaging. Some Essentials. Principles of radiography/terminology Basic anatomy Operative procedures and radiographic technique Dose limitation Health & Safety. Major Directional Terms. AP Position?.
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Advanced DiagnosticImaging Studies Theatre Imaging
Some Essentials • Principles of radiography/terminology • Basic anatomy • Operative procedures and radiographic technique • Dose limitation • Health & Safety
AP Position? • Actually PA for supine patient as beam enters posteriorly
Imaging in Theatres • Discussion. • Mobile x-ray units. (CXR etc) • Image Intensifier units
Mobile Fluoroscopy units • Flexibility • Ease of use • Safety features • Cross infection issues • Radiation protection • Image quality • Transportation / storage • Image storage facilities
Mobile fluoroscopy units • Flexibility • Ability to move in small environments • Accurate controls • Full isocentric movements • Clear measurement markings • Manual handling considerations • Low base height • Foot / hand exposure devices
Mobile fluoroscopy units • Ease of use • Laser marking facility • Accurate positioning • Hand rails Easy movement • Quick access interlocks • Simplistic design • Clear user features • Ability to manipulate data from base unit
Mobile fluoroscopy units • Image review / print • Ability to review data on dual monitor display • Freeze –transfer –archive features • Manipulate data remotely from unit base • Input patient demographics • Ability to review “thumbnail” images • Ability to play movie clips
Safety Features • Cable protection on wheels • Minimal trailing cables • Electro-mechanical brakes • Counter balance construction • “Glide” mode • Key operation (IR(ME)R) • Handles to pull / push unit • Earthed units • Monitor & Image intensification unit • Cable connections
Infection Control • Bodily fluids •Areas where bodily fluids may settle: –Crevasses (Rails) –Wheels –Screw heads –Cables •Easily cleaned surfaces •Ability to cover with sterile drapes
Radiation Protection • Pulsing option • Up to 70% dose reduction • Visual collimator blades –Iris –Semi-transparent • CARE dose facility • Image rotation facility • Integrated DAP device • Exposure time / dose reading • Warning light / audible warning
Limiting dose • X-rays are potentially harmful to patients and staff • All radiological procedures should seek to keep dose “as low as reasonably practicable” ( ALARP) • This is the principle of Optimisation as stipulated in the IRRs – therefore not optional; required by law
Limiting dose • Collimation – decreasing the size of the radiation field • Use of shutters or iris collimator • Keep intensifier face as close as possible to the patient • Reduces x-ray output necessary to achieve acceptable image • Reduces image magnification and blurring
Limiting dose • Try to position correctly before exposing • Think about whether the required area is under the intensifier face before pushing expose button • Use of laser positioning • Use of anatomical landmarks • Lead rubber coats for staff • Must be worn by all in controlled area i.e the operating theatre • Avoid staff hiding behind other • Lead rubber gonad shielding for patient
Contrast Difference between adjacent densities on a radiograph The number of black, white and grey tones that appear on a radiograph Controlled by the energy of the x-ray beam
kVp Main controlling factor in radiographic contrast Selected by radiographer for every exposure Has a major influence on quality of the radiograph
kVp and contrast Photoelectric absorption probability aZ3 E3 Z atomic number E beam energy As kVp increases absorption by photoelectric effect rapidly decreases causing a reduction in radiographic contrast
kVp Determines the energy of the x-ray beam Low energy beam is easily absorbed Differential absorption increases High contrast High energy beam penetrates body more easily Differential absorption decreases Low contrast
Interprofessional Working…. • Communication skills • Cooperative attitude • Space awareness • Professional performance • Compromise
Interpreting surgeon’s requirements • Flash • Shot • Picture • Yes • All can mean “Please expose the patient and show me an image”
Orthopaedic procedures • Hip pinning • Dynamic Hip Screw (DHS) • Cannulated screws
Nailing procedures • Femoral(most common), tibial, humeral nail • Intramedullary –often requires reaming (drilling) of medullary canal • Proximal and distal locking screws
Locking screws • Proximal locking usually drill guide device • Distal locking trickier and done by manual location of where to drill • Needs to achieve round holes to enable correct angulation of drill
Guidance systems Designed to make life easier for surgeon to place locking screws with better accuracy. Reduces need for x-rays and reduces time under anaesthetic.
Tibial Nailing • Less common as tends to be less successful than femoral nail • Tibia has less vigorous blood supply than femur, and drilling out tends to compromise further. Problems with non-union • External frames becoming more popular (Taylor spatial, Ilizarov)
Other Procedures • Central Lines • Give long-term central venous access for patients requiring it e.g chemotherapy
Peripherally inserted central catheter (PICC line) Typical screening position –intensifier on top