Analysis of patients and operators radiation doses in transcatheter aortic valve implantation (TAVI) and evaluation of radiation risks Poster No.: C-2993 Congress: ECR 2010 Type: Topic: Scientific Exhibit Physics in Radiology Authors: A. del Vecchio, P. Signorotto, A. Colombo, M. Montorfano, F. Maisano, R. Bellanca, R. Calandrino; Milan/IT Keywords: DOI: Dose Area Product, Effective dose, Interventional Cardiology 10.1594/ecr2010/C-2993 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. www.myesr.org Page 1 of 11
Purpose Degenerative aortic valve stenosis is the most frequent pathology in elderly populations in advanced countries. Surgical aortic valve replacement remains the gold standard for the treatment but there are certain critical situations and a large numbers of patients rejected for surgical intervention. Transcatheter Aortic Valve Implantation (TAVI) represents a new and efficient alternative to the surgical approach for patients defined as "non operable". The aim of this work is the evaluation of patients and staff dosimetry during TAVI procedures; values were than compared with standard cardiological procedures. Methods and Materials Patients dose evaluation Data on 76 TAVI performed in 2007 and 2008 were collected and compared with 5549 CA and/or PTCA executed in the Cardiology Department. Procedures were carried out by means of a transmission camera for the direct measurement of the Dose Area Product (DAP) expressed in Gycm 2 For Effective Dose estimation (E) the coefficient proposed by Boegaert et al. (6) as the results of a recent multi centric Belgian study were used. Operator dose evaluation For operators dose evaluation, presence and positioning during procedures were considered. Operator doses for interventional cardiology have been were calculated from routine personal dosimetry, for every single each TAVI procedures, electronic dosimeters and TLD bracelets were distributed. Images for this section: Page 2 of 11
Fig. 1: Corevalve Page 3 of 11
Fig. 2: Staff positioning during a TAVI Page 4 of 11
Results TABLE 1 - Estimated risk for fatal event for different procedures DAP (Gycm2) Effective Dose (msv) Risk of fatal event (per million cases) CA 34.1 6 252 0.025 Complex CA 57.4 10.2 428 0.043 PTCA 111 19.6 823 0.082 Complex PTCA 150.5 26.6 1117 0.112 TAVI 218.5 38.7 1625 0.163 Increase of estimated risk % (ICRP 103) TABLE 2 - Average DAP for different access of TAVI procedure Access N cases DAPave(Gycm2) Transfemoral 66 270.95 Transapical 7 78.71 Transaxillary 3 174.67 The data show the importance of access choice: large reductions in patient dose appear in passing from the transfemoral to the transapical approach (p = 0,0007) or from the transaxillary to the transapical (p = 0,0057), whereas dose decrease between transfemoral and transaxillary does n'ot appear significant (p = 0,1403). TABLE 3 - Age related risk from different proceures (in blu additional risk < 0.1 %) Risk coefficient (x 10-2 Sv-1) (NRPB4) Risk of fatal malignancy per patient (%) CA Complex Ca PTCA Complex PTCA TAVI 30-39 4.5 0,027 0,046 0,088 0,120 0,174 40-49 4.2 0,025 0,043 0,082 0,112 0,163 Page 5 of 11
50-59 4 0,024 0,041 0,078 0,106 0,155 60-69 3.1 0,019 0,032 0,061 0,082 0,120 70-79 1.6 0,010 0,016 0,031 0,043 0,062 80+ 0.75 0,005 0,008 0,015 0,020 0,029 Population weighted average 5.85 0,035 0,060 0,115 0,156 0,226 Dose receipt by the patients due to interventional cardiology could be high. Aortic valve implantations represent a risk double that of coronary stents interventions. It should be noted that average age is very high, and that this technique is still evolving and chosen only when the patient is considered nonsurgical; for these reasons, fatal risk could may be considered acceptable. TABLE 4 - Mounthly operators dosimetry values for standard procedures Effective Dose (msv) Equivalent Dose in Hands (msv) Equivalent Dose in Lens and Thyroid (msv) Cardiologist 0,17 (0-1,74) 8,39 (0-14,46) 2,959 (6,87-10, 5) Technician 0,023 (0-0,11) Not evaluated 0,437 (0-2,94) Nurse 0,021 (0-0,04) Not evaluated 0,277 (0-0,73) TABLE 5 - Operators dosimetry values for one TAVI procedure Effective Dose (msv) Equivalent Dose in Hands (msv) Anaesthetist 1 operator 0,004 (0,001-0,010) 0,365 (0,074-1,215) Anaesthetist 2 operator Not evaluated 0,137 (0,032-0,319) Cardiologist 1 operator 0,0414 (0,001-0,304) 0,354 (0,055-1,391) Cardiologist 2 operator 0,0011 (0,001-0,002) 0,157 (0,009-0,321) Heart surgeon 1 operator Heart surgeon 2 operator 0,0348 (0,015-0,167) 1,023 (0,299-3,104) Not evaluated 0,192 (0,088-0,331) Technician 0,0011 (0,001-0,003) 0,084 (0,013-0,454) Nurse 0,0008 (0,0005-0,001) Not evaluated Page 6 of 11
TABLE 6 - Evaluation of increase of fatal risk for interventional cardiology workers Risk coefficient (x 10-2 Sv-1) Annual increase of estimated risk due to routine activity Increase of estimated risk due to a single TAVI procedure ICRP 60 5,6 1,14 x 10-4 2.32 x 10-6 ICRP 103 4,2 8,57 x 10-5 1,74 x 10-6 TAVI is a procedure that exposes the cardiology team to a supplementary potentially significant dose. Results reported in tables are average values measured during procedures performed by qualified operators, with very good management and the capability to limit time of exposition. It can be understood that 50 TAVI/year could take a double of the occupational risk coefficient for the first operator. Images for this section: Page 7 of 11
Fig. 1: Percutaneous heart valve remove Page 8 of 11
Fig. 2: Electronic personal dosimetry Page 9 of 11
Conclusion Given the increase in frequency of cardiologic pathologies in advanced countries, it is reasonable to assume that in the near future such kinds of interventions could be extended to younger people. For these reasons optimization is becoming necessary both in diagnosis and therapy such as: increased use of radioprotection devices, specific training, optimization of protocols and operators work load. References 1.Eltchaninoff H, Tron C, Cribier A. Percutaneous implantation of aortic valve prosthesis in patients with calcific aortic stenosis: technical aspects. J Interv Cardiol. 16(6):515-21; 2003 2.Litzler PY, Cribier A et al. - Surgical aortic valve replacement after percutaneous aortic valve implantation: what have we learned? - J Thorac Cardiovasc Surg. 2008 Sep;136(3):697-701; 2008 3.Colombo A, Bianconi L, Montorfano M et al. (2005) - Severe aortic stenosis successfully treated with percutaneous aortic valve implantation - Ital Hearth J Suppl 2005 May;6(5):291-6; PMID: 15934426 4.Alfieri O, Maisano F, Colombo A. (2005) - Future of transcatheter repair of the mitral valve - Am J Cardiol. 2005 Dec 19;96(12A):71L-75L; PMID: 16399096 5.Aranzulla TC, Cosgrave J, La Canna G, Maisano F, Montorfano M, Sangiorgi G, Colombo A. (2008) - Percutaneous treatment of periprosthetic mitral valve leaks: is it just a futile exercise? - Ann Thorac Surg. 2008 Sep;86(3):996-8; PMID: 18721600 6.Bogaert E, Bacher K, Thierens H (2008) - A large-scale multicentre study in Belgium of dose area product values and effective doses in interventional cardiology using contemporary x-ray equipment - Radiation Protection Dosimetry, 2008;128(3):312-23; PMID: 17681964 7.International Commission on Radiological Protection - ICRP Publication 85: Avoidance of Radiation Injures from Medical Interventional Procedures - Annals of the ICRP Volume 30(2) - Oxford: Pergamon Press, 2000 Page 10 of 11
8.IAEA - International basic safety standards for protection against ionizing radiation and for the safety of radiation sources - IAEA Safety series, N. 115 - Vienna, 1996 Personal Information Page 11 of 11