Brennan, Patrick

D'helft, Catherine

Hughes, Ciara

McFadden, Sonyia

McGee, A

Rainford, Louise

Winder, J. R.

English

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OPTIMISATION OF RADIATION DOSES IN INTERVENTIONAL CARDIOLOGYCatherine D’Helft1, Sonyia Mc Fadden2, Allison McGee1, Louise Rainford1, Ciara Hughes2, John Winder2 and Patrick C Brennan1.1 School of Diagnostic Imaging, University College Dublin, St Anthonys, Herbert Avenue, Dublin 4.2 School of Applied Medical Science & Sports Studies, Faculty of Life & Health Sciences, University of Ulster at Jordanstown, Shore Rd, Newtownabbey, BT37 OQB.  INTRODUCTION The purpose of this paper introduce details of a mayor study which will determine methods of reducing the radiation doses for adult and paediatric interventional cardiology procedures whilst maintaining image quality and diagnostic efficacy of examinations. Local x-ray dose reference levels for the cardiology examinations will be established and it is intended that these will form a benchmark in Irish Cardiovascular centres against which individual performance can be judged and corrective action taken if necessary. The project involves collaboration between University College Dublin, University of Ulster and hospitals troughout Ireland. It is funded by the Health Research Board (HRB).BACKGROUND All x-ray examinations represent a biological risk proportional to the radiation dose delivered to an individual [1]. Radiation doses should therefore be kept as low as reasonably achievable, consistent with good image quality. The number of interventional radiological procedures performed in radiology departments throughout the world has risen in recent years because of their cost-effectiveness when compared with surgical procedures [2]. At present, cardiac radiological intervention procedures are recognized as an important component of healthcare given the high incidence of cardiovascular disease in this country. Ireland has the highest rate of heart disease in Europe, accounting for 42% of all deaths [3].The number of patients referred for cardiac interventional procedures has been increasing in recent years as a result of the cost-effectiveness of these techniques relative to the surgical alternative of invasive surgical procedures.  Patients undergoing cardiac interventional techniques can be treated as outpatients or day-cases, requiring a reduced hospital stay compared with surgical candidates.  The advantages of reduced costs, increased patient throughput and fewer complications have driven the increased need for various cardiac interventional techniques worldwide.Given the potential for high patient doses and large dose variability both within and between cardiac imaging centres during the cardiac interventional procedures identified by past researchers [4], radiation dose optimisation and standardisation of practice have become critically important, representing an essential component of any health strategy aimed at improving the quality of health care provision. It is anticipated that important quality benefits will follow from the implementation of the best practice identified by the proposed work.Due to the involvement of prolonged fluoroscopic exposure times, interventional procedures, particularly cardiovascular studies, are often responsible for some of the highest patient and staff radiation doses experienced in diagnostic radiology [5].  Such exposures increase the risk of stochastic radiation effects (cancer), and regularly cross the threshold dose above which direct, deterministic effects such as erythema, epilation and ulceration are experienced by the patient. It has been estimated that in the UK, interventional cardiology studies are responsible annually for a collective effective dose of 914 manSieverts [6] and deterministic effects involving skin such as tissue desquamation, ulceration and necrosis, sometimes requiring graft therapy are being increasingly reported [7]. Based on data collected in a preliminary survey performed for this study, and data available in other countries, it is estimated that the Republic of Ireland’s population of about 4 million will undergo a minimum of 15,000 cardiac interventional examinations per year, resulting in an annual collective dose of about 165 man Sieverts.  Recent HRB-funded work and other studies have identified major causal agents responsible for high radiation doses in non-interventional fluoroscopy and have established cost-effective methods of reducing patient dose for non-fluoroscopic work [8]. If similar dose reducing methods can be found in cardiac interventional work reduction in terms of man- Sieverts might be substantial.  This project aims to provide a framework both nationally and globally for patient dose optimisation during interventional cardiovascular examinations. Through cross-border collaboration, diagnostic reference levels for cardiac interventional procedures that truly reflect national clinical practice in the field of cardiac imaging will be proposed. To date no such reference dose levels have been established in this country for cardiac interventional radiological procedures despite these being required under current legislation [9]. In the UK, implementation of diagnostic reference levels for general radiography and non-interventional fluoroscopic examinations, has been shown to reduce radiation exposure by up to 45%. Dose reductions of this magnitude would substantially reduce the risk of cancer induction, and minimise, deterministic radiation effects, thereby offering important benefits for  patients and radiological staff. The Department of Health and Children’s strategy is to provide a healthcare system which ensures equity, quality and accountability, the fulfilment of which requires evidence-based research in order to define best practice. The multidisciplinary team of researchers in this work will attempt to meet this challenge for specified cardiac interventional procedures. METHODOLOGYThe research team consists of -Ms Catherine D’Helft				Ms Sonyia Mc FaddenDr. Patrick Brennan				Dr. John WinderDr. Louise Rainford				Dr. Ciara HughesMs. Allison Mc Gee				Dr. Andrew SandsDr. Michael Casey				Mr.RoyMooneAnd the cardiac suite staff of 15 participating hospitals, spread throughout Ireland. The study will consist of two main parts:  the first part will measure radiation doses that are currently being administered for a range of paediatric and adult interventional cardiovascular examinations (Table 1).Table 1:Examinations to be investigated in the current work.Paediatric Examinations	Adult ExaminationsPatent ductus arteriosus	Coronary angiographyAtrial septal defects	Percutaneous coronary angioplasty (PTCA),Ventricular septal defects	Pacemaker insertionPulmonary valvuloplasty/Pulmonary artery angioplasty +/- stenting,	Co-arctation of the aorta	Aortic valvuloplasty	Occlusion of collateral vessels	Septostomy procedures	Dose measurements will be collated from participating centres in the Republic of Ireland and Northern Ireland. From the information gathered potential diagnostic reference levels will be established. Work practices for the examinations will be recorded, analysed and techniques associated with low radiation dose and acceptable/high image quality will be identified. Following this stage of the work, a series of experimental-based dose reducing studies using tissue equivalent anthropomorphic phantoms and psychophysical tests will be performed. Cost-effective, dose-reducing measures will be introduced both singularly and in combination, and both radiation dose and image quality levels will be measured. Finally, based on the results of this experimental work, proposed optimum practice for each interventional cardiovascular examination (Table 1) will be tested in clinical departments. It is anticipated that data provided by this study will result in optimised techniques for cardiac interventional procedures, and will benefit the large numbers of patients in Ireland and elsewhere undergoing cardiac interventional procedures.PILOT STUDYA cross border pilot study is currently being undertaken. The researchers at this point of the project wish to express their appreciation to all the centres that have agreed to participate in this work, as without the co-operation of clinical staff this research would not be possible.REFERENCES1. Lindell B.1996. The risk philosophy of radiation protection. Radiat Prot Dosim: pp 157-163.2. Faulkner K., Vano E. 2001. Deterministic Effects in Interventional Radiology. Radiat. Prot. Dosim. 94(1-2), pp 95-98.  3. Irish health.com. Heart disease- facts and figures. http://www.irishhealth.com/clin/cholesterol/chol-facts.html4. Bernardi G, Padovani R, Morocutti G, Vano E, Malisan M R, Rinuncini M, Spedicato L, Fioretti P M. 2000. Clinical and Technical Determinants of the Complexity of Percutaneous Transluminal Coronary Angioplasty: Analysis in relation to radiation exposure. Catheterization and Cardiovascular Interventions 51:1-95. Vano E, Gonzalez L, Fernandez JM, Guibelalde E. 1995. Patient dose values in interventional radiology.  Br J Radiol. Nov;68(815): pp 1215-20.   6. Broadhead DA, Chapple CL, Faulkner K, Davies ML, McCallum H. 1997. The impact of cardiology on the collective effective dose in the North of England.  Br J Radiol. May;70(833): pp 492-7.  7. Koenig TR, Wolff D, Mettler FA, Wagner LK. 2001. Skin injuries from fluoroscopically guided procedures part 1, characteristics of radiation injury. Am J Roentgenol. Jul; 177(1): pp 3-118. Carroll E & Brennan PC (2000). The establishment of diagnostic reference levels for barium enemas and barium meals. British Journal of Radiology.73(supp):  1019. SI 478 of 2002. European Communities (Medical Ionising Radiation Protection) Regulations 2002. Government Statutory Office: Dublin

OPTIMISATION OF RADIATION DOSES IN INTERVENTIONAL CARDIOLOGY

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OPTIMISATION OF RADIATION DOSES IN INTERVENTIONAL CARDIOLOGY

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