The number of fluoroscopy-guided procedures in cardiology is increasing over time and it is appropriate to wonder whether technological progress or change of techniques is influencing patient exposure. The aim of this study is to examine whether patient dose has been decreasing over the years. Patient dose data of more than 7700 procedures were collected from two cardiology centres. A steady increase in the patient dose over the years was observed in both the centres for the two cardiological procedures included in this study. Significant increase in dose was also observed after the installation of a flat-panel detector. The increasing use of radial access may lead to an increase in the patient exposure. The monitoring of dose data over time showed a considerable increase in the patient exposure over time. Actions have to be taken towards dose reduction in both the centre

Aroua, A.

Bochud, F.

Samara, E. T.

Stauffer, J.-C

Verdun, F. R.

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FLUOROSCOPY-GUIDED PROCEDURES IN CARDIOLOGY: ISPATIENT EXPOSURE BEING REDUCED OVER TIME?E. T. Samara1, A. Aroua1, J.-C. Stauffer2, F. Bochud1 and F. R. Verdun1,*1Institute of Radiation Physics (IRA), University Hospital Center and University of Lausanne, Rue duGrand-Pre´ 1, 1007 Lausanne, Switzerland2Cardiology Department, CHUV-UNIL, Rue du Bugnon 46, 1011 Lausanne, Switzerland*Corresponding author: francis.verdun@chuv.chThe number of fluoroscopy-guided procedures in cardiology is increasing over time and it is appropriate to wonder whether tech-nological progress or change of techniques is influencing patient exposure. The aim of this study is to examine whether patientdose has been decreasing over the years. Patient dose data of more than 7700 procedures were collected from two cardiologycentres. A steady increase in the patient dose over the years was observed in both the centres for the two cardiological proceduresincluded in this study. Significant increase in dose was also observed after the installation of a flat-panel detector. The increasinguse of radial access may lead to an increase in the patient exposure. The monitoring of dose data over time showed a consider-able increase in the patient exposure over time. Actions have to be taken towards dose reduction in both the centres.INTRODUCTIONThe number of interventional cardiology procedureshas increased over the years. Only in Europe, a 3.2-fold increase in coronary angiograms from 1992 to2004 was estimated, resulting in 2 million proceduresperformed in 2004; more than 3 million proceduresare expected in 2010(1). In the same study, the trendsfor both coronary angiography (CA) and stentingwere also observed to be rising. In the USA, thenumber of percutaneous coronary interventions hasconsiderably increased without a simultaneouschange in patient demographics, which means thatmore patients today are referred to interventionalprocedures than open operations(2). Reasons for thisincrease may include changes in patient demo-graphics in some countries, increased operatorclinical skills, the development and availability ofpurpose-designed cardiological fluoroscopic systems.Many procedures that previously required opensurgery or were impossible are now safely and effec-tively performed using interventional techniques.However, there is significant concern related to theradiation exposure of patients undergoing fluorosco-pically guided procedures. Patients may suffer fromradiation-induced skin injuries (skin erythema, per-manent epilation, skin necrosis) and if younger, therisk of cancer may be significantly higher(3).National and international authorities point to theincreasing number of fluoroscopy-guided proceduresand recommend patient dose surveys and the usageof dose reference levels (DRLs) to optimise theexposure(3,4). The aim of this study was to examineif radiation doses tend to increase or decrease overthe years and investigate whether new technologyand techniques have an impact on the dose deliveredto patient.MATERIALS AND METHODSThe survey took place in two large cardiologycentres (A and B). Two procedures were chosen tobe analysed: CA and percutaneous transluminalcoronary angioplasty (PTCA). Annual data for thetwo procedures were collected from each centre,including values of dose–area product (DAP) andfluoroscopy time (T ). Data for centre A were col-lected from 2001 to 2007 and for centre B from 2004to 2007. In centre A, the fluoroscopy unit Integris(Philips Medical System, The Netherlands) wasequipped with a 23-cm image intensifier (II). In2004, a new unit Allura XPS FD10 (Philips MedicalSystem, The Netherlands) was installed, equippedwith a flat-panel detector (FPD). This change ininstallation was taken into consideration during thedata analysis. In centre B, a fluoroscopy unitDiagnos Poly 2C (Philips Medical System, TheNetherlands) was also equipped with a 23-cm II. Inboth the centres, a DAP meter was installed on theX-ray equipments. In centre B, patient data includedinformation about the vascular access approach(femoral or radial access). The difference in the twoapproach techniques was examined for theireffect on radiation dose. For each procedure, themean, median, maximum and 75 % values wereestablished. Non-parametric analysis [Mann–Whitney U (M–W) test] was used to compare thedifferences between the results. Statistical data analy-sis was performed with the SPSS 15 softwarepackage (SPSS Inc, Chicago, IL, USA).RESULTSIn total, data from 4742 procedures were collectedfrom centre A and 3027 procedures from centre B.# The Author 2010. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oxfordjournals.orgRadiation Protection Dosimetry (2010), Vol. 139, No. 1–3, pp. 271–274 doi:10.1093/rpd/ncp307Advance Access publication 22 January 2010The results for the DAP values in the CA andPTCA procedures are presented in Tables 1 and 2and the fluoroscopy times T are shown in Tables 3and 4, respectively. The 75 % values were used tocompare the differences between patient doses overthe years. A 2.5- and 1.7-fold increase was observedfor the DAP values during CA procedure in centresA and B, respectively. Statistically significantincrease in the DAP values was observed between2004 and 2005, when the FPD was installed.However, the DAP values were shown to be signifi-cantly higher every year since 2004. T has alsoincreased over the years in both the centres. TheDAP values have also increased with respect toPTCA procedures. This increase was found to bestatistically significant for both the centres. However,the T values were found to be constant over time forcentre A. In centre B, T showed a significantdecrease especially between 2005 and 2006( p-value ¼ 0.009).A small increase in the number of cases treatedwith radial access was observed for centre B(Figure 1). The results were compared by M–W testto test any significant difference in patient dosebetween the radial and femoral access. A significantdifference was confirmed in the case of CA forboth DAP (Z ¼ 4.317, p-value , 0.001) and T (Z ¼5.669, p-value , 0.001). The results for PTCAprocedures were not found to be significantlydifferent (DAP: Z ¼ 0.072, p-value ¼ 0.943 and T:Z ¼ 0.358, p-value ¼ 0.721).DISCUSSIONContrary to the expectations, the present workshows that radiation doses in cardiology procedureshave increased over time in the two centres moni-tored despite the fact that the staff remained thesame and all operators were senior interventionists.On the other hand, fluoroscopy time was found toremain constant or has slightly decreased during thesame period.The DRLs concept was proposed in 1990by International Commission on RadiologicalProtection (ICRP) and is accepted as a managementtool for radiation exposure in medical imaging pro-cedures. The main objective of the DRLs is patientdose reduction for a given examination. DRLsshould be used to ensure a balance between patientdose and image quality. It is essential to bemonitored over time. The use of this concept isstraightforward in radiography or CT examinations;however, it presents some limitations when it is usedin fluoroscopy where the procedures are less standar-dised. In 2008, the Swiss Federal Office for publichealth published DRLs for diagnostic and thera-peutic procedures in radiology and cardiology. TheDRLs in terms of DAP and T, for CA areTable 1. Mean, median, 75 % percentile and maximum values of DAP (Gy.cm2) for CA procedures.Centre A Centre BMean Median 75 % Maximum Z P-value Mean Median 75 % Maximum Z p-value2001 30 25 35 255 1.593 0.111 — — — — — —2002 31 25 38 197 1.725 0.103 — — — — — —2003 33 26 40 260 1.654 0.098 — — — — — —2004 39 29 47 361 2.720 0.101 40 31 50 33 1.649 0.0992005 48 40 63 229 5.726 ,0.001 72 35 66 95 5.978 ,0.0012006 61 52 81 345 6.258 ,0.001 118 49 87 413 1.298 0.1942007 62 55 86 235 — — 102 54 86 579 — —Table 2. Mean, median, 75 % percentile and maximum values of DAP (Gy.cm2) for PTCA procedures.Centre A Centre BMean Median 75 % Maximum Z p-value Mean Median 75 % Maximum Z p-value2001 60 54 75 241 0.675 0.500 — — — — — —2002 63 51 77 252 2.975 0.301 — — — — — —2003 62 53 81 356 1.875 0.061 — — — — — —2004 63 53 85 2043 7.673 ,0.001 121 88 152 1540 0.688 0.4922005 132 110 177 746 3.734 ,0.001 126 99 159 1310 4.008 ,0.0012006 166 137 214 1214 6.521 ,0.001 264 112 209 7990 1.920 0.0552007 201 144 288 986 — — 212 127 199 9840 — —E. T. SAMARA ETAL.27270 Gy.cm2 and 7 min and for PTCA 100 Gy.cm2and 20 min, respectively. The comparison of theDRLs with the 75 % of DAP and T showed thatnational DRLs were exceeded in both the centres. Incentre A, the DAP values were below the DRLvalues from 2001 to 2005 and from 2001 to 2004 forCA and PTCA, respectively. For CA procedures, theDRLs were surpassed 14 and 18 % in 2006 and2007, respectively. In the case of PTCA, the DRLswere exceeded more than 80 % the last 3 y. However,the DRLs for the T were not exceeded for CA andwere exceeded 5 % only in 2007 for PTCA. Forcentre B, in the CA procedures the DRLs were sur-passed in 2006 and 2007. The DAP values forPTCA were found to be consistently higher than theDRLs. The main concern is that DAP valuesexceeded the DRLs and they are continuouslyrising. Clearly, something must be done with respectto dose optimisation.Concerning centre A, it appears that during theyears 2001–03 the annual DRLs were systematicallywell under the DRLs adopted in Switzerland forcardiac procedures. A significant increase in dosewas observed in 2004, when the conventional II wasreplaced by a FPD. Differences in T were not foundto be statistically significant, suggesting that pro-cedures of a similar complexity were performed.In centre A, even with superior technologyinstalled, doses steadily increased from 2004 to2007, exceeding the national DRLs in Switzerland.Centre A, in which patient exposure was significantlylower than centre B in the past, is now overtakingcentre B where a conventional II is still in use. Doserate measurements were performed in order tounderstand the cause of such dose increases incentre A and the values obtained were comparablewith dose rates delivered with the previous technol-ogy. No major differences were noticed at thatlevel. One of the main problems was, andcertainly remains, the X-ray beam collimation.Figure 1. Percentage of radial access in centre B for years2004–07.Table 4. Mean, median, 75 % percentile and maximum values of T (min) for PTCA procedures.Centre A Centre BMean Median 75 % Maximum Z p-value Mean Median 75 % Maximum Z p-value2001 9.7 8.2 11 39 1.203 0.229 — — — — — —2002 9.8 7.6 11 46 2.542 0.203 — — — — — —2003 9.7 7.8 13 52 15.399 ,0.001 — — — — — —2004 13 8.0 14 84 1.752 0.080 26 15 25 324 0.611 0.5412005 10 8.4 13 43 1.598 0.110 17.2 14 23 75 2.611 0.0092006 11 9.2 14 66 2.310 0.101 16 13 20 87 1.742 0.0822007 13.2 9.1 21 52 — — 14 11 19 58 — —Table 3. Mean, median, 75 % percentile and maximum values of T (min) for CA procedures.Centre A Centre BMean Median 75 % Maximum Z p-value Mean Median 75 % Maximum Z p-value2001 3.7 2.5 2.4 50.6 2.128 0.033 — — — — — —2002 3.7 2.8 4.6 31.4 6.542 0.056 — — — — — —2003 3.8 2.6 4.8 35 21.48 ,0.001 — — — — — —2004 5.7 3.0 5.0 89 6.579 ,0.001 9.2 3.5 7.7 305 2.031 0.0422005 3.4 2.6 3.8 22 3.503 ,0.001 6.7 4.4 7.0 115 2.038 0.0422006 4.0 2.9 5.0 39 6.128 ,0.001 5.9 4.0 6.6 82 0.492 0.6222007 4.2 3.1 5.1 65 — — 5.7 4.0 6.3 85 — —FLUOROSCOPY-GUIDED PROCEDURES IN CARDIOLOGY273Interventionists tend to use larger fields of view,since the dynamic range of the FPD does not leadto inadequate image quality even when lung tissue ispresent in the image. Beam collimation cannot fullyexplain the continuous increase in patient dose. Anincrease over time (especially for CA as shown inFigure 1) of the radial access instead of the standardfemoral access was noticed. Radial access is a rela-tively new approach technique, which is clinicallyadvantageous for the comfort of the patient. It alsoallows shorter hospitalisation of the patient leadingto a significant cost reduction. One of the maininconveniences of the radial approach, even thoughthis is still under controversy, is that it may increasepatient dose as well as staff dose. As an example,radial access has been shown to result in higherdoses to patients in the case of CA, but not in thecase of PTCA. Larrazet et al.(5) reported higherDAP values and fluoroscopy time with radial accessthan with femoral access during PTCA procedures.However, their study was not randomised. Sandborget al.(6) also reported higher exposure with radialartery access in CA and coronary interventions.Higher values in the cases with radial access werealso found in the study by Philippe et al.(7). On thecontrary, Geijer and Persliden(8) reported no differ-ence in radiation dose between the two differenttechniques for interventional procedures.The use of DRLs in fluoroscopy is associated withcertain limitations; the main one being that they donot take into account the complexity of the pro-cedure (e.g. elective or emergency procedure, mono-or multi-vessels procedure, etc.). This might beimproved in the near future since several groups(9,10)have proposed introducing complexity indices torefine the DRL values and thus increase itsacceptance in the clinical world. In spite of theselimitations, the results of this study, that are basedon the analysis of the DRL values over time, clearlydemonstrate that a major effort has to be made toensure patient safety in cardiology. In the presentstudy, the dose increase cannot be explained only bya drastic increase in the complexity of the procedure.The population demographics considered during thissurvey and the personnel of the centres remained thesame.CONCLUSIONIn conclusion, radiation doses in cardiology pro-cedures performed under fluoroscopy guidanceappeared, in the case here, to increase over time andbasic rules of practical radiation protection have tobe re-introduced among the interventionists. Thishas been demonstrated using the DRL concept evenif this concept has to be used with care since at themoment it does not take into account proceduralcomplexity. In these high-dose procedures, it shouldbe a priority that medical physicists be involved toensure patient and personnel safety. Technologicalprogress is not directly associated with patient dosereduction.REFERENCES1. Cook, S., Walker, A., Hu¨gli, O., Togni, M. and Meier,B. Percutaneous coronary interventions in Europe: preva-lence, numerical estimates, and projections based ondata up to 2004. Clin. Res. Cardiol. 96(6), 375–382(2007).2. McLean, T. R. In New York State, do more percuta-neous coronary interventions mean fewer or morecomplex referrals to cardiac surgeons? Am. HeartHosp. J. Winter 6(1), 30–36 (2008).3. International Commission on Radiological Protection.Avoidance of radiation injuries from medical interven-tional procedures. ICRP Publication 85. Ann. ICRP30(2) (Oxford and New York: Pergamon Press) (2000).4. European Union. Council Directive 97/43 Euratom, onhealth protection of individuals against the dangersionizing radiation in relation to medical exposure, andrepealing. Directive 84/466. Euratom. Official J. Eur.Communities L 180, 22–27 (1997).5. Larrazet, F., Dibie, A., Philippe, F., Palau, R., Klausz,R. and Laborde, F. Factors influencing fluoroscopy timeand dose-area product values during ad hoc one-vesselpercutaneous coronary angioplasty. Br. J. Radiol.76(907), 473–477 (2003).6. Sandborg, M., Fransson, S. G. and Pettersson, H.Evaluation of patient-absorbed doses during coronaryangiography and intervention by femoral and radialartery access. Eur. Radiol. 14(4), 653–658 (2004).7. Philippe, F., Larrazet, F., Meziane, T. and Dibie, A.Comparison of transradial vs. transfemoral approach inthe treatment of acute myocardial infarction withprimary angioplasty and abciximab. Catheter.Cardiovasc. Interv. 61(1), 67–73 (2004).8. Geijer, H. and Persliden, J. Radiation exposure andpatient experience during percutaneous coronary inter-vention using radial and femoral artery access. Eur.Radiol. 14(9), 1674–1680 (2004).9. Balter, S., Miller, D. L., Vano, E., Ortiz Lopez, P.,Bernardi, G., Cotelo, E., Faulkner, K., Nowotny, R.,Padovani, R. and Ramirez, A. A pilot study exploringthe possibility of establishing guidance levels in x-raydirected interventional procedures. Med. Phys. 35(2),673–680 (2008).10. Padovani, R., Bernardi, G., Malisan, M. R., Van˜o´, E.,Morocutti, G. and Fioretti, P. M. Patient dose relatedto the complexity of interventional cardiology pro-cedures. Radiat. Prot. Dosimetry 94(1–2), 189–192(2001).E. T. SAMARA ETAL.274

Fluoroscopy-guided procedures in cardiology: is patient exposure being reduced over time?

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