What is interventional radiography? (IR)
Difference to surgery?
- a subspecialty of radiology which performs minimally invasive procedures under image guidance to diagnose and treat diseases.
- IR procedures have less risk, less pain and shorter recovery time than surgical alternatives
What type of procedures do IR include?
- vascular intervention
- cancer diagnosis and treatment
- GI intervention
- GU intervention
- neurovascular intervention
- MSK intervention
- trauma
- spinal intervention
What imaging equipment is used in IR?
depends on the service, but examples:
- single plane ceiling suspended c-arm
- floor mounted c-arm
- biplane system for neuro
- hybrid theatre for complex vascular procedures
Who are part of the multidisciplinary IR team?
- radiologists
- IR radiographers
- IR nurses
- IR CSW (clinical support worker)
- RDA (radiology department assistant)
- admin team
- anaesthetists/ODP
What types of imaging are used in IR?
- ultrasound for vessel or organ access
- fluoroscopic screening
- digital subtraction
- road map/fluoro-fade
- rotational angiography
What does fluoroscopic screening allow?
What is fluoroscopy used to position guide and visualise in IR?
How to keep doses low?
- fluoroscopy allows a real time, live image
- in IR, fluoroscopy is used to position guide wires, balloons and stents.
- Gives a low dose visualisation of vessels and organ systems when used with contrast.
- To keep radiation doses low, radiographer adjusts the frames per second as low as is reasonably practicable without affecting the image quality
What is Digital Subtraction Angiography (DSA) used for?
What is the process?
What does it rely on?
What do radiographers do post-procedure?
What are the DSA processing options?
- used when high quality imaging of blood vessels is required
- pre-contrast image of anatomy acquired
- masked image to remove the background
- contrast injected and DSA acquired at appropriate frame rate to view vessels
- DSA relies on patient cooperation, patient movement degrades the image quality
- Post processing by the radiographers will optimise image quality for diagnosis.
DSA processing options:
- optimisation of windowing to show anatomy
- moving the mask to improve vessel visualisation
- pixel shifting to reduce movement artefact
- image summation to enhance vessel visualisation
What is road map/fluoro fade?
What is the process?
What is reduced?
- acts as a sat nav for guidance of wires and devices
- live fluoroscopy is superimposed over a previous DSA or contrast enhanced fluoro image that demonstrates the pathology to be treated
- reduces overall radiation and contrast dose due to less need for repeat DSA acquisitions
What happens during rotational angiography?
(C-arm, mask, contrast, software)
When is rotational angiography useful?
When is it used?
- C-arm is positioned over area of interest and isocentred with the table
- Mask acquired by rotation around the patient
- Contrast injected and c-arm rotates back around the patient to acquire images at high frame rate
- software collates the images into a 3D model of the vessels.
- useful for when the course of a vessel is unclear in 2D
- used when very specific vessel selection is important
(e.g. intra-arterial chemotherapy or cerebral aneurysm coiling)
What are common IR angiography procedures?
- angioplasty or stenting of narrowed vessels
- stenting of aortic aneurysms (EVAR)
- embolisation of bleeding vessels or aneurysms
- thrombolysis of clotted vessels
- line insertions
- long-term feeding tube insertions
- nephrostomy insertion
- renal or liver biopsy
What is the method for accessing vessels/organ systems?
- Seldinger technique is used to access vessels or organ systems.
- pulsatile blood flow upon entry
- J-tip guidewire is advanced
- Needle is removed leaving guidewire inside of the vessel
- Sheath is advanced over guidewire
- Sheath advanced to skin entry
- Guidewire and dilator removed
Radiation protection within IR
- IR procedures are often…resulting in..
- measures must be taken to…
- IR procedures are often complex and lengthy, resulting in high radiation exposure for patients and staff
- measures must be taken to reduce the risk of radiation related complications
Reducing PATIENT dose
- what DRLs?
- who is responsible for what?
- national DRLs don’t exist for IR, local DRLs are agreed
- radiographers and radiologists are responsible for making the dose as low as possible without compromising image quality.
What are 9 actions that should be taken to reduce PATIENT dose in interventional radiography?
1) following justification and IR(ME)R processes
2) adequate exposure factors
3) collimation and filtration
4) pulsed fluoroscopy
5) as low as possible frame rate for DSA
6) knowledge of catheter and wire selection
7) keep screening time as short as possible
8) only use fine focus or magnification if needed
9) use software like fluoro fade/roadmap
What are the ways to reduce STAFF dose?
- TIME - reduce your time near the radiation source
- lower FFD/SID to reduce scatter
- reduce screening time to keep dose as ALARA
- DISTANCE - staff should utilise inverse square law
- SHIELDING - use all lead screening and PPE available in the room, including movable screens
What is important about PPE?
- wearing the correct PPE is essential
- it should fit well
- includes lead gown, thyroid shield, lead glasses, and sometimes leg, breast or upper arm shields
- QA screening is completed annually
- PPE must be stored carefully to avoid damage
How is staff dose monitored?
- All IR staff are monitored
- Operators wear body, eye and finger badges
- Dose records compared against legal dose constraints
- If dose report is higher than usual, this is investigated and action taken to ensure PPE is in good condition and being worn correctly
Contrast in IR
- iodinated contrast is used to..
- often high doses…
- makes IR procedures…
- iodinated contrast is used to opacify vessels and body systems
(omnipaque 240/300, visipaque 270, optiray 300/350) - often high doses >150mls of contrast used intra-artierally or intra-venously
- makes IR procedures high risk for contrast induced complications
e.g. contrast induced nephropathy (acute kidney injury)
e.g. allergic reactions
How can risks of contrast be reduced?
- What 5 things can be checked before contrast is given?
- Operator?
- Staff?
Before contrast is given, check:
- allergies
- previous contrast reactions
- kidney function (eGFR blood test)
- heart problems
- asthma/hayfever/eczema
- ensure operator is aware of any risk factors
- ensure all staff know what to do in event of a contrast reaction
- What can carbon dioxide (CO2) be used for in IR?
- How does it work?
- What intervention can it only be used for?
- can be used as a contrast in the case of renal impairment or contrast allergy
- CO2 bubbles displace the blood in the vessel creating a negative space, reducing attention in the vessel.
- CO2 dissolves rapidly and is absorbed by the body thus no risk of embolus or thrombosis
- Can only be used in peripheral intervention but not neuro intervention.
Consent within IR
- What is consent?
- IR procedures require..
- What are the things done?
- What about patient unable to consent?
- consent is a patient agreement for a health professional to provide care. patients may indicate their consent non-verbally, orally or in writing
- IR procedures require consent to be completed, usually written
- discussion between the patient + clinician of risk vs benefit
- 2 step consent process to give the patient time to reflect and make an informed choice/ask questions
- Patients unable to consent for themselves should have a mental capacity assessment, best interest decision meeting and consent from 4 completed.
Governance within IR
- what audits and reviews?
- what measures?
- what checklist? What does it include?
- similar to surgery - competency audits, morbidity and mortality reviews, patient outcome audits
- stringent infection prevention and control (IPC) measures - all operators undergo ANTT audit and scrub technique
World Health Organisation safe surgery checklist:
- ensures right procedure, for right patient, at the right time
- site marking for procedure site
- morning team briefing
- sign in prior to operator scrubbing for procedure
- time out prior to needle to skin
- sign out at the end of procedure
- debrief at the end of the list
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CT hardware and cross-sectional image viewing11
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CT physics27
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CT optimisation44
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Brain Anatomy and Pathology59
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Contrast Media / Pharmacokinetics47
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MRI Principles30
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MRI Safety31
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Ultrasound Principles45
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Principles of screening24
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Biological effects of radiation17
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Mammography - role, purpose & anatomy14
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Mammography - image formation20
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Nuclear Medicine22
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Fluoroscopy41
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Interventional Radiography22
