Radiation dose levels assessment in mammography

Transcription

1 Radiation dose levels assessment in mammography Poster No.: B-0871 Congress: ECR 2013 Type: Scientific Paper Authors: C. N. Lourenço, P. Sousa, S. Rodrigues, A. F. Abrantes, L. P. V. Ribeiro, K. B. Azevedo, R. P. P. A. Almeida; Faro/PT Keywords: DOI: Radiation physics, Professional issues, Mammography, Dosimetry, Radiation safety, Audit and standards /ecr2013/B-0871 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. Page 1 of 14

2 Purpose to measure radiation dose levels in mammography of two institutions; to determine Entrance Skin Dose (ESD) and Mean Glandular Dose (MGD) using a dynamic table made through Excel software created for the purpose; to compare obtained values with international guidelines. Methods and Materials In accordance to institutional guidelines, the approval of this study was obtained from the review board and the participation agreement was obtained from each patient. Sample: From March to April 2012, a survey of exposure parameters (kv and mas), sociodemographic and anthropometric characteristics (age, gender, weight and height) was made from female patients that were referred to mammography exams (548 examinations) in two different institutions (A and B). This sample included craniocaudal (CC) and mediolateral oblique (MLO) views. Variables: In this study the independent variables were exposure parameters (kv and mas) and the anthropometric characteristics of patients (age, gender, weight and height). The dependent variables were the values of ESD and MGD. Instruments: For calculations purposes it was created a dynamic table through Excel software with mathematic formulas which included data like exposure parameters, equipment specifications, anthropometric characteristics and examination details (compressed breast thickness, applied compression, type of filter) to easily obtain the required values. The examinations were performed in two different equipments: GE Senographe 800T and GE Senographe Essential. For viability of measurements, the dose rate and quality control using the detector RF Unfors Xi were carried out. Page 2 of 14

3 Procedures: For data collection purposes two phases were considered. First, was made a collection of data relating to patients, exposure parameters and exam type, among other important information during the mammography examinations. These were inserted into the dynamic table to automatically obtain the values of ESD and MGD. In another phase, was performed a quality control of the equipments used in this study using the detector RF Unfors Xi. For data analysis was used IBM SPSS V.20 for Windows. This software allowed performing a descriptive analysis and the 75 th Percentile of ESD and MGD calculations in order to estimate the DRL's for mammography examinations in the two institutions under study. The sample was subjected to Kolmogorov-Smirnov test to determine its normality, a fact which hasn't been shown. Results Figure 1 show the age groups included in this study. Page 3 of 14

4 Fig. 1: Sample age groups Table 1 show the calculated values of ESD per view of each institution. Page 4 of 14

5 Table 1: ESD values per view Table 2 show the calculated values of MGD per view of each institution. Page 5 of 14

6 Table 2: MGD values per view As we could see, there were no large discrepancies between institutions A and B for ESD and MGD. Normality Test Using the Kolmogorov-Smirnov test was verified that, for a 95% of confidence level, there wasn't a normal distribution. Therefore were used non-parametric tests. 75 th Percentile The DRL's were defined based on the calculation of the 75 th Percentile of the average of dose distributions applied on radiological procedures. Figures 2, 3 and 4 show the establishment of DRL's for mammography examinations (both views and complete exam) in this study. Page 6 of 14

7 Fig. 2: 75th Percentile for CC views For CC views was obtained an average of 1.29 mgy MGD and a 75th percentile of 1.43 mgy, for institution A. For CC views in institution B, the average MGD was 1.25 mgy and the 75th percentile was 1.60 mgy. Page 7 of 14

8 Fig. 3: 75th Percentile for MLO views For MLO views the average MGD was 1.49 mgy and the 75th percentile was 1.62 mgy, for institution A. As for the institution B, the average MGD was 1.53 mgy and the 75th percentile was 1.95 mgy. Page 8 of 14

9 Fig. 4: 75th Percentile for complete examination Regarding the complete examination (4 views), the average MGD in the institution A was 1.40 mgy for a 75th percentile of 1.58 mgy. For institution B was calculated an average of 1.39 mgy for MGD and a 75th percentile of 1.83 mgy. Mann-Whitney Test Was performed the non-parametric Mann-Whitney Test (# = 0,05) with the aim of verify the differences between applied doses in examinations of both institutions (table 3). Page 9 of 14

10 Table 3: Mann-Whitney Test (# = 0,05) It was found that for CC views, the differences in dose between both institutions were statistically significant (U = 5321, p = 0.013). However, the same was not found to MLO views because there were no statistically significant differences (U = 7441, P = 0.906). Comparison with international guidelines Table 4 show de comparison made between the obtained values in this study and the international guidelines. Page 10 of 14

11 Table 4: Comparison with international guidelines The average MGD obtained values for both institutions in CC and MLO views as for a full examination (4 views) were lower than international guidelines. Considering the comparisons presented, the DRL's are in general lower than those practiced by other countries. Conclusion The dynamic table created during this study proved to be a useful tool for calculating immediate radiation doses to which patients were exposed, and inform them. The calculated ESD values were generally lower than international guidelines. In values of MGD, there were some differences between the two institutions. This fact is explained according to the differences between the equipments that were used and modifications in the breast tissue of patients. Page 11 of 14

12 Concerning the relationship between the estimated DRL values for this study and DRL's of other countries, it was found that the former are in general lower than those seconds. However, these results were for comparative purposes only, as it was not possible to guarantee the same conditions of the examinations between this study and others. References 1. American College of Radiology. (2008). Practice guidelines. ACR guidelines for the performance of screening and diagnostic mammography. 2. ARPANSA. (2011, July 13). National Diagnostic Rference Level Fact Sheet. Retrieved January 17, 2012, from Australian Radiation Protection and Nuclear Safety Agency: ndrlfactsheet.cfm 3. Bouzarjomehri, F., Mostaar, A., Ghasemi, A., Ehramposh, M., & Khosravi, H. (2006). The Study of Mean Glandular Dose in Mammography in Yazd and the Factors Affecting It. Iranian Journal of Radiology, pp Edmonds, K. (2009). Diagnostic reference levels as a quality assurance tool. pp European Comission. (2008). Radiation Protection nº 154. European Guidance on Estimating Population Doses from Medical X-Ray Procedures. Oxfordshire. 6. ICRP. (2007). Recommendations of the International Commission on Radiological Protection. Retrieved December 20, 2011, from ICRP: Free_extract.pdf 7. Kunosic, S., Ceke, D., Kopric, M., & Lincender, L. (2010). Determination of mean glandular dose from routine mammography for two age groups of patientes. HealthMED, pp Marconato, M. (2009, June 16). Niveaux de Réfeérence Diagnostic NRD en Suisse. Berne. 9. Minister du Travail, de L'emploi et de la Santé. (2012). Décrets, arrêtés, circulaires. Journal Officiel de la République Française. 10. Ogundare, F., Odita, A., Obed, R., & Balogun, F. (2009, June 21). Mean glandular doses for women undergoing mammographic breast screening in Oyo, Nigeria. The College of Radiographers, pp Paknyat, A., Rostam Pour Samarin, E., Jeshvaghane, N., Paydar, R., Fasaei, B., Karamloo, A., et al. (2011, August 3). Evaluation of patient dose in some mammography centers in Iran. Radiation Protection Dosimetry, pp Page 12 of 14

13 Personal Information C. Lourenço, Department of Radiology, Health School - University of Algarve, Av. Dr. Adelino da Palma Carlos, Faro, Portugal. Tel: Fax: catarinalourenzo@gmail.com P. Sousa, PhD, Department of Radiology, Health School - University of Algarve, Portugal. pesousa@ualg.pt S. Rodrigues, Master, Department of Radiology, Health School - University of Algarve. srodrigues@ualg.pt A. F. Abrantes, PhD, Department of Radiology, Health School - University of Algarve, Member of CESNOVA (Sociology Studies Center of New University of Lisbon), Portugal. aabrantes@ualg.pt L. P. V. Ribeiro, PhD, Department of Radiology, Health School - University of Algarve, Member of Cdaf (Research Center of Sports and Physical Activity), Portugal. lpribeiro@ualg.pt K. B. Azevedo, Department of Radiology, Health School - University of Algarve, Portugal; PhD student at Cranfield University, UK. kbazevedo@ualg.pt R. P. P. Almeida, Department of Radiology, Health School - University of Algarve, PhD student at Faculty of Health Sciences - University of Beira Interior, Portugal. rpalmeida@ualg.pt Page 13 of 14

14 Fig. 5 Page 14 of 14