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Radiation protection of staff during interventional cardiology

» Is the exposure to the cardiologist much higher than to non-interventionalists?

The radiation exposure of the cardiologist is of significance principally for following three reasons:

  • location - has to work inside and near the X-ray tube and cannot be too far away from the patient; 
  • time - the radiation 'ON' time in a well utilized catheterization laboratory is typically a few hours per day (say 60-200 minutes) in contrast to a radiography room where it is generally two-four minutes for a workload of 100-200 radiographs per day; 
  • shielding - attenuation by lead apron can be to the order of 90-97% depending upon the lead content of the apron whereas higher attenuation is possible with structural shielding for those who work at the console outside the X-ray room. 

Further factors to consider are:

  • radiation intensity - in the fluoroscopy mode, intensity is lower by a factor of few tens as compared to the radiography or cine mode; 
  • exposure parameters - typically they are automatically controlled by equipment and are higher for patients with high body mass; 
  • cardiologists may work in the catheterization laboratory only few days a week (against five or six days a week for the staff at the console). 

Considering all these factors, the exposure to intervantionalists can be many times higher than a staff who works only at the console located just outside the X-ray room. 

» Is there a risk of cataract after several years of work in a catheterization laboratory?

Proper use of radiation protection tools (most importantly the protective screens or lead glass barrier) and techniques can prevent effects such as cataracts for work in catheterization laboratory to cover full professional life.

At the moment, it is not clear if these early changes will lead to lens opacity. The interventional practice is increasing and some interventionalists perform many procedures (aproximately 1000 procedures per year or more). Measurements and calculations indicate that if radiation protection devices and procedures are not used, the threshold for cataract can be exceeded with possibility of radiation induced lens injury. At the same time, it is clear that proper use of radiation protection can avoid lens injuries even with high workload.

There is a published report of radiation induced cataracts of one interventional radiologist and two nurses. Results from recent studies conducted by the IAEA reveal the prevalence of radiation associated posterior lens opacities ranged from 38 - 52% for interventional cardiologists, 21 - 45% for nurses. Estimated cumulative ocular doses ranged from 0.01 Gy to 43 Gy.

The subject of radiation induced cataract is under review by the International Commission on Radiological Protection (ICRP).

» Can I work my full professional life in a catheterization laboratory and have no radiation effects?

Yes it is possible.

Under optimized conditions when the equipment is periodically tested and it is operating properly, when personal protective devices (lead apron of suitable lead equivalence of 0.25 to 0.5 mm and wrap around type, protective eye wears or protective shields are used for head/face and leg region), when proper technique is employed, it is possible to achieve negligible probability of all known radiation effects during a full professional life. There are situations where patient protection poses a great challenge, not so much in staff protection where it can reasonably achieved.

» What are the typical radiation doses associated with diagnostic and therapeutic interventional procedures?

Typical values in terms of effective dose and dose area product (DAP) values are presented in Tables 1 and 2 below:

Table 1: Mean effective doses and DAP values from diagnostic interventional procedures 

Diagnostic
interventional
radiological/
cardiological
procedures
Mean
Effective doses
(mSv)Mean
DAP
value
(Gy.cm2)Equivalent
number of
PA chest
radiograph
(each 0.02 mSv)
Upper
extremity
angiography
0.56 12 28
T-Tube
cholangiogram
2.6 10 130
Cerebral
angiography
3 85.7 150
Coronary
angiography
3.1 26 155
Lower extremity 3.5 14 175
ERCP 3.9 15 195
Thoracic
aortography
4.1 34.5 205
Pulmonary
angiography
5   250
Arterial
pressures* 
7   350
Peripheral
arteriography
7.1 27.2 355
Abdominal
aortography 
12   600
Renal
angiography
13.7 86 685
Mesenteric
angiography
22.1 85 1105

* Fluoroscopically guided catheterization for the measurement of pulmonary artery pressure

(Table 1 was adopted from publications: BOR, D., T., SANCAK, T., OLGAR et al. Comparison of effective doses obtained from dose-area product and air kerma measurements in interventional radiology, Br. J. Radiol. 77 916 (2004) 315-322. and HART, A., and WALL, B.F., Radiation exposure of the UK population from medical and dental x-ray examinations, NRPB-W4 (2002).)

Table 2: Mean effective doses and DAP values from therapeutic interventional procedures 

Interventional
Radiological/
cardiological
therapeutic
procedures
Mean
Effective
doses
(mSv)Mean
DAP
value
(Gy.cm2)Equivalent
number of
PA chest
radiograph
(each 0.02 mSv)
Upper extremity arterography  0.9 18 45
Nephrostomy 3.4 13 170
Thrombolysis 3.5 13.5 175
Pacemaker implant 4 17 200
Lower extremity arterography 4.5 18 225
Ureteric stenting 4.7 18 235
Cerebral embolisation 5.7 202 285
Vascular stenting 10.4 40 520
Renal angiography 11.7 81 585
Insertion of caval filters 12.5 48 625
Kidney stent insertion 12.7 49 635
Biliary intervention   54  
PTCA, stent placement 15.1 58 755
Bile duct drainage 18.4 70.6 920
Cardiovascular embolisation 19.5 75 975
Radio frequency ablation 20.3 54.6 1015
Valvuloplasty 29.3 162 1465
TIPS 53.6 206 2680
Pelvic vein embolisation 60   3000
Uterine fibroid embolisation 77.5 298.2 3875

(Table 2 was adopted from BOR, D., T., SANCAK, T., OLGAR et al. Comparison of effective doses obtained from dose-area product and air kerma measurements in interventional radiology, Br. J. Radiol. 77 916 (2004) 315-322, HART, A., and WALL, B.F., Radiation exposure of the UK population from medical and dental x-ray examinations, NRPB-W4 (2002), METTLER, F.A., HUDA, W., YOSHIZUMI, T.T., MAHESH, M., Effective Doses in Radiology and Diagnostic Nuclear Medicine: A Catalog. Radiology 248 1 (2008) 254-263, MILLER, D.L., BALTER, S., COLE, P.E., et al., Radiation doses in interventional radiology procedures: The RAD-IR study: Part I: overall measures of dose, J. Vasc. Interv. Radiol. 14 6 (2003) 711-727.)

Read more:

  • CIRAJ-BJELAC, O., REHANI, M.M., SIM, K.H., LIEW, H.B., VANO, E., KLEIMAN, N.J., Risk for radiation induced cataract for staff in interventional cardiology: Is there reason for concern? Catheter. Cardiovasc. Interv. 76 (2010) 826-834. 
  • HART, D., HILLIER, M.C., WALL, B.F., Doses to patients from medical x-ray examinations in the UK: 2000 review. NRPB-W14 (2002). 
  • KUON, E., et al., Radiation-reducing planning of cardiac catheterization, Z. Kardiol. 94 10 (2005) 663-673. 
  • MARSHALL, N.W., CHAPPLE, C.L., KOTRE, C.J., Diagnostic reference levels in interventional radiology, Phys. Med. Biol. 45 12 (2000) 3833-3846. 
  • PANTOS, I., PATATOUKAS, G., KATRITSIS, D.G., EFSTATHOPOULOS, Patient radiation doses in interventional cardiology procedures, Current Cardiology reviews 5 (2009) 1-11. 
  • REHANI, M.M., ORTIZ-LOPEZ, P., Radiation effects in fluoroscopically guided cardiac interventions- keeping them under control, Int. J. Cardiol. 109 2 (2006) 147-151. 
  • VANO, E., et al., Lens injuries induced by occupational exposure in non-optimised interventional radiology laboratories, Br. J. Radiol. 71 847 (1998) 728-733. 
  • VANO, E., et al., Skin radiation injuries in patients following repeated coronary angioplasty procedures, Br. J. Radiol. 74 887(2001) 1023-1031. 
  • VANO E., KLEIMAN N.J., DURAN A, REHANI M.M., ECHEVERRI D., CABRERA M., Radiation cataract risk in interventional cardiology personnel, Radiat Res. 174 4 (2010) 490-495.