Lifetime risk of radiation-induced cancer from screening mammography

Lifetime risk of radiation-induced cancer from screening mammography Poster No.: C-0558 Congress: ECR 2015 Type: Scientific Exhibit Authors: R. M. K. M.Ali, A. England, P. Hogg; Manchester/UK Keywords: Radioprotection / Radiation dose, Mammography, Dosimetry, Dosimetric comparison DOI: 10.1594/ecr2015/C-0558 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 14

Aims and objectives To propose a method for evaluating the effective lifetime risk of radiation-induced cancer from screening mammography and to present initial data comparing risks from different national screening programmes. Methods and materials A dosimetry ATOM phantom with thermoluminescent dosimeters and a perspexpolyethylene breast phantom, described by Bouwman, et al. [1], were used to measure organ doses during a standard four view screening mammogram (Fig 1). Imaging was undertaken using a HOLOGIC Lorad Selenia full field digital mammographic unit. Examined breast mean glandular dose (MGD) was calculated as reported by the Institute of Physics and Engineering in Medicine (IPEM)[2]. The effective radiation dose was calculated and effective risk was modeled for a range of client ages. E = #wtht Where E is the effective radiation dose, wt is the tissue weighting factor and HT is the radiation dose in tissue T[3]. R=#rTHT Where R is the effective risk, rt is the lifetime of cancer risk for tissue T per unit equivalent dose to that tissue, and HT is the equivalent dose for tissue T[4]. The lifetime cancer risk of different tissues (rt) are taken from BEIR VII - Phase 2 report of National Academy of Sciences (2006)[5]. Since these values are presented for each decade of female age, they are plotted against the ages to get the value for each year of female life. Page 2 of 14

Fig. 1: Phantom positioning arrangement (a) a diagram of phantom positioning arrangement in craniocaudal (CC) projection, (b) ATOM phantom with designed breast phantom in CC projection, (c) ATOM phantom with designed breast phantom in mediolateral oblique (MLO) projection. References: Radiography, University of Salford - Manchester/UK Images for this section: Page 3 of 14

Results Radiation absorbed dose of each organ was obtained by averaging the dose value in different locations inside that organ. In addition to the examined breast, contralateral breast, thyroid, thymus, brain, salivary glands, lung, and bone marrow received radiation dose more than 1µGy during screening mammography (Table 1). Page 5 of 14

Table 1: Female organ radiation dose from one screening mammography. References: Radiography, University of Salford - Manchester/UK Page 6 of 14

Effective dose and effective risk were calculated twice: one depending on examined breast organ dose and the other depending on examined breast MGD (Tables 2, 3). Effective dose in µsv was calculated for one screening event (four views) depending on the latest tissue weighting factors that have been recommended by ICRP (2007)[3]. The generated data of this calculation is presented in (Table 2), together with individual organs absorbed dose that were used to calculate the required effective radiation dose. Table 2: Female effective dose from one screening mammography. * This percent represents the portion of bone marrow received radiation dose during mammography. It is adapted from ICRP report 70 (1995) and it is distributed as 0.8% in clavicle, 7.9% Page 7 of 14

in cranium, 3.9%in C-spine, 0.8% in mandible, 16.1% in ribs, 2.8% in scapula, and 3.1% in sternum [6]. References: Radiography, University of Salford - Manchester/UK After the calculation of effective risk of screening mammography for each year of life, the total effective risk of cancer incidence due to screening mammography was calculated across different country based mammography screening programmes because these programmes are differ in term of commencement and ending ages and time interval between the screens (Table 3). Table 3: Total effective risk (during woman life) of screening mammography according to different mammography screening programmes. References: Radiography, University of Salford - Manchester/UK Page 8 of 14

Images for this section: Page 9 of 14

Table 1: Female organ radiation dose from one screening mammography. Page 10 of 14

Table 2: Female effective dose from one screening mammography. * This percent represents the portion of bone marrow received radiation dose during mammography. It is adapted from ICRP report 70 (1995) and it is distributed as 0.8% in clavicle, 7.9% in cranium, 3.9%in C-spine, 0.8% in mandible, 16.1% in ribs, 2.8% in scapula, and 3.1% in sternum [6]. Page 11 of 14

Table 3: Total effective risk (during woman life) of screening mammography according to different mammography screening programmes. Page 12 of 14

Conclusion This study proposed a method to evaluate lifetime effective risk of radiation-induced cancer from screening mammography in order to compare different mammography screening programmes. This method was easy to conduct and the generated data are more understandable than if it were in form of effective dose. According to the results of this study the main contributor to the effective risk was the risk of breast cancer. This was not only because of the examined breast dose but also because of the contralateral breast dose. Work will be extended to assess the repeatability of results for a single machine and also across a range of mammography machines. Personal information Raed Mohammed Kadhim M.Ali, MSc. Physiology and medical physics department, College of medicine, University of Kufa. PhD student at University of Salford. r.m.k.mali@edu.salford.ac.uk raed_medical@yahoo.com Andrew England, PhD. Radiography directorate, School of health sciences, University of Salford. a.england@salford.ac.uk Peter Hogg, FCR. Radiography directorate, School of health sciences, University of Salford. p.hogg@salford.ac.uk References 1. Bouwman, R.W., et al., Phantoms for quality control procedures in digital breast tomosynthesis: dose assessment. Phys Med Biol, 2013. 58(13): p. 4423-38. Page 13 of 14

2. 3. 4. 5. 6. Moore, A.C., et al., The commissioning and routine testing of mammographic X-ray systems. 2005, Institute of physics and engineering in medicin: York. ICRP, I., The 2007 Recommendations of the International Commission on Radiological Protection (Publication 103). Annals of the ICRP, 2007. 37(2-4): p. 1-332. Brenner, D.J., We can do better than effective dose for estimating or comparing low-dose radiation risks. Ann ICRP, 2012. 41(3-4): p. 124-8. National Academy of Sciences, Health Risks from Exposure to Low Levels of Ionizing Radiation: BEIR VII - Phase 2. 2006, National Academies Press: Washington. ICRP, I., Basic anatomical and physiological data: The skeleton (publication 70). Annals of the ICRP, 1995. 25(2): p. 1-80. Page 14 of 14