SAFETY IN THE CATH LAB
• Radiation safety has layers• 1. ALARP• 2. Use dose saving equipment• 3. Inverse square law• 4. Protection• 5. Monitoring
1. Keep radiation dose to patient As Low As Reasonably
Practical (ALARP)
• This will reduce your dose too• And that of everyone else in the lab
2a. Useful dose reducing features
• The radiographer• They can suggest dose saving features
• Like reducing fluoroscopy pulse rates
• … and frame rate• (and remind you to take your foot off the pedal)
2b. Skin Dose reduction in practice
• Save our Skins working group• Work done in northwest cath labs• Dose reduction in excess of 50%• 7 sites involved• Poster at entrance to main hall
● The Cardiologist should provide information to the patient about radiation risk within the consent process.● The Cardiac High Dose Flowchart will be displayed in the Cardiac Catheter Lab and staff will refer to it for advice.
● If it is considered prior to a procedure that a skin dose of 3 Gy or greater is likely (e.g. large patients undergoing complex angioplasty procedures), or the patient has had a procedure in the previous week, then the patient should be counselled before the procedure regarding potential risks and side-effects and informed consent be obtained by the clinician dealing with the patient.
● During the procedure if a dose of 5 Gy or above is reached, further imaging should be deferred for 7 days where possible.
● If a patient has received a potential skin dose of greater than 5 Gy (250 Gycm2), the patient should be followed up after 14-21 days. The patient should be provided with an information card post procedure
Imaging protocol optimisation
Save Our SkinsIdentification and follow-up of patients at risk of skin injury from cardiac catheterisation procedures
● May 2007: A physics survey highlights concerns over the level of skin doses reached following certain catheter lab procedures in some NW centres
● August 2007: Following the survey, two NW centres develop an initial skin dose policy based on recommendations of the ICRP
Original policy: patient threshold dose for investigation set at 3 Gy (single or cumulative dose), above which patient to be recalled for skin assessment 10-14 days post procedure
● 2009: Following the patient skin injury, regional Radiation Protection Supervisors involved in PCI met with Medical Physics Expert support from North Western Medical Physics (NWMP) to form High Skin Dose Group.Aim: to step develop the standard policy
● 2009 : revised policy to be used as standard for NW group formulated following further recommendations ● skin injury threshold of 6 Gy was proposed by a local oncologist based on radiotherapy protocols.
● the relationship between skin dose and DAP was determined by NWMP to be approximately 1 Gy skin dose for each 50 Gy.cm2 (5,000 cGy.cm2)
Revised policy: threshold dose for post procedure follow up increased to 5 Gy
● Cumulative doses only to be included if procedure is repeated within 2 weeks and sum of doses > 5 Gy● Time period increased to 14-21 days for follow up appointment● Skin care advice cards for patients introduced after development by the group
● Group continues to meet to discuss and improve implementation of skin dose policy in the North West
History and development
Skin care card
Figure 1. Example of the skin dose card used in the North West
● The Skin Care Card evolved following a series of High Skin Dose Group meetings.● The group decided the best way to track and advise patients who received high doses was by an informational card.
● The card is given to every patient exceeding 150 Gycm2 or the equivalent of 3 Gy. The credit-card sized card is issued in a plastic wallet to be kept by the patient and presented to catheter lab staff if called for further procedures.
● This means that patients having another x-ray procedure within 14 days can have their cumulative dose estimated and, if it is likely to exceed 5 Gy, be advised of the potential risk of skin injury prior to the procedure.
● The patient’s radiation reading is also kept for a period of 2 calendar months in a register at the treating hospital.● The card was designed to be generic so that all hospitals could use it by simply adding the details of the cardiac centre
concerned to the wallet; with a phone number for patients to contact should they notice skin reactions.
● PCI procedures can cause deterministic injury following long fluoroscopy times● 2000: UK PCI procedures becoming more complex in Cardiac Catheter Laboratories
● 2008: High Skin dose effects (>5 Gy) had not yet been reported in the UK from these procedures. Only seen in USA in text books.
● 2008: No specific, structured protocols in place for monitoring or prevention of these effects in patients in UK catheter labs.● 2009: North West UK Hospital receives notification of deterministic effects from a high skin dose (>25 Gy) PCI procedure,
carried out in 2008.
Background
Figure 2. Flowchart for //decision making on patients with high skin dose//
● At the Manchester Royal Infirmary in 2007, a departmental equipment upgrade gave the opportunity to re-evaluate frame rates in routine use.
● An initial drop from 15 to 7.5 frames per second proved difficult in practice for cardiologists and radiographers.
● Over a period of twelve months, the frame rate was gradually lowered from 15 to 10 and then 10 to 7.5 frames per second for PCI procedures.
● Simultaneously, the fluoroscopy pulse rates were reduced from 12 to 7.5 pulses per second.
● Other procedures have also benefitted from similar changes.● Additional benefits have included increasing the lifetime of the X-ray tubes.
Consent and staging
Date 2002-2007 2007 2008 2009 2010
Average DAP (Gy.cm2 35-40 35-40 30-35 20-30 <20
Frame rate (fps) 12-15 15 10 7.5 7.5
Fluoro pulse rate (pps) 15 15 10 7.5 7.5
Field of view (cm) 15 15 15 20(+live zoom)
20(+live zoom)
Table 1. Imaging Protocols adopted by a North West Cardiology Department
●The Skin Care Card evolved following a series of High Skin Dose Group meetings.●The best way to track and advise patients who received high doses ●Given to every patient exceeding 150 Gycm2 or the equivalent of 3 Gy. ●The credit-card sized card in a plastic wallet to be kept by the patient● Presented to catheter lab staff if called for further procedures.●If further procedure within 14 days, decision matrix is used.●The patient’s radiation reading is also kept in a register at the treating hospital.●Generic card but each hospitals adds the site name and a phone number ●Patients contact should they notice skin reaction●Referral then for OPD and dermatologist or plastic surgeon
Skin care card
3. Inverse Square Law• Standing a foot further from patient’s chest = dose saving
• Use longer catheters (or extensions)
• Use an injection pump for coronaries
• Do not approach patient during runs
4 (a) Protection• What is the lead equivalence of your gown
• For first operators it should be 0.35-0.5mm le
• Depending on level of scatter encountered
• Everyone else at least 0.25 mm le• Ensure annual safety screening
4.(b) Protection • Always stand behind something thick• … or something dense• You will find something appropriate nearby
5. Monitoring• Last month’s body dose• Last year’s eye dose• Do you wear your dosimeters?
• Some radiation injuries are genetic