Raed Mohammed Kadhim M.Ali M.Ali

The aim of this study was to estimate the skin radiation dose received by adults’ patients undergoing most common eight X-ray examinations. The study was conducted in three hospitals in three different Iraqi cities: Najaf, Babylon and Salah AL-Din. A minimum number of 10 patients were considered for each type of X-ray examination in each hospital. The skin radiation dose calculation was performed by mathematical equation using exposure factors, namely, X-ray tube voltage (kVp), tube loading (mAs) and source-skin distance (SSD). The skin radiation dose values were obtained for all patients involved in this study who undergoing skull (AP and Lat), cervical (Lat), chest (PA), abdomen (AP), lumbar (Lat), pelvis (AP) and knee (AP) examinations. The resulted data were analyzed and compared with international reference doses. The average skin radiation dose ± standard deviation (SD) for the three hospitals were 0.77±0.43mGy for skull (AP), 0.66±0.39mGy for skull (Lat), 0.63±0.34mGy for cervical (Lat), 0.28±0.25mGy for chest (PA), 4.36±2.92 mGy for abdomen (AP), 4.37±2.30mGy for lumbar (Lat), 1.65±1.09mGy for pelvis (AP) and 0.40±0.25 mGy for knee (AP) examinations. For majority of the considered radiographic examinations Balad general hospital recorded the highest skin radiation dose. Overall most of the recorded radiation doses were within the internationally acceptable dose levels with some variations amongst different hospitals.

Abstract Objectives To compare Mean Glandular Dose (MGD) and effective dose from digital breast tomosynthesis (DBT) screening with that from full field digital mammography (FFDM) screening. Method To simulate compressed breasts, two Perspex-polyethylene breast phantoms were used, one phantom for compressed breast in craniocaudal and the other for compressed breast in mediolateral oblique. An adult ATOM dosimetry phantom was loaded with high sensitivity thermoluminescence dosimeters; the phantom was then positioned on Hologic Selenia Dimensions mammographic machine to imitate DBT and 4-view FFDM screening. Organ radiation doses were measured from 4-view DBT and 4-view FFDM (craniocaudal and mediolateral oblique views for each breast). Organ radiation doses were used to calculate effective dose from one screening session. Results MGD for DBT was 3.6 mGy; MGD for FFDM was 2.8 mGy. For DBT, other organs (e.g. thymus, lungs, salivary glands, thyroid, contralateral breast and bone marrow) radiation dose was also higher than for FFDM. The use of DBT for breast cancer screening increases the effective dose (E) of one screening session by 22%. E for DBT was 0.44 mSv; E for FFDM was 0.34 mSv. Conclusion The use of DBT for breast cancer screening increases the radiation dose to screening clients.

Abstract Objective The objective of this study was to investigate the impact of contralateral breast shielding on the risk of developing radiation-induced cancer from four-view full-field digital mammography (FFDM) screening. Methods A poly methyl methacrylate-polyethylene breast phantom and adult ATOM dosimetry phantom were used to measure organ dose on four FFDM machines using craniocaudal and mediolateral oblique projections for each breast. A lead rubber shield of 0.25 mm equivalent lead thickness was used to protect the contralateral breast. Organs dose, effective dose, and effective risk were calculated. For effective risk estimations, the impact of the shield was considered for the routine screening views. Results The contralateral breast dose was reduced by more than 95%. For each FFDM machine, contralateral breast dose reduction in μGy were 35.20 reduced to 1.93, 41.40 reduced to 0.01, 22.85 reduced to 1.24, and 22.76 reduced to 1.66. Effective risk reduction was significant ( P < .05). For all FFDM machines, a small reduction was identified in sternum bone marrow dose due to the use of contralateral breast shield. Conclusions The results of the study demonstrate the value of a contralateral breast shield. More research is required to determine whether such a shield has clinical utility.

Abstract Objectives: The objective of the study was to use the initial mean glandular dose (MGD) arising from the first screening mammogram to estimate the individual total screening lifetime effective risk. Methods: Organ doses from full-field digital mammography (FFDM) screening exposures (craniocaudal and mediolateral oblique for each breast) were measured using a simulated approach, with average breast thickness and adult ATOM phantoms, on 16 FFDM machines. Doses were measured using thermoluminescent dosimeters accommodated inside the ATOM phantom; examined breast MGD was calculated. Total effective risk during a client's lifetime was calculated for 150 screening scenarios of different screening commencement ages and frequencies. For each scenario, a set of conversion factors were obtained to convert MGD values into total effective risk. Results: For the 16 FFDM machines, MGD contributes approximately 98% of total effective risk. This contribution is approximately constant for different screening regimes of different screening commencement ages. MGD contribution remains constant, but the risk reduced because the radiosensitivity of all body tissues, including breast tissue, reduces with age. Three sets of conversion factors were obtained for three screening frequencies (annual, biennial, triennial). Three relationship graphs between screening commencement age and total effective risk, as percentages of MGD, were created. Conclusions: Graphical representation of total risk could be an easy way to illustrate the total effective risk during a client's lifetime. Screening frequency, commencement age, and MGD are good predictors for total effective risk, generating more understandable data for clients than MGD. Keywords: Breast dose; Mammography; Radiation hazards; Screening.

Abstract Background and purpose: The performance of mammography screening programmes is focussed mainly on breast cancer detection rates. However, when the benefits and risks of mammography are considered, the risk of radiation-induced cancer is calculated for only the examined breast using Mean Glandular Dose (MGD). The risk from radiation during mammography is often described as low or minimal. This study aims to evaluate the effective lifetime risk from full field digital mammography (FFDM) for a number of national screening programmes. Material and methods: Using an ATOM phantom, radiation doses to multiple organs were measured during standard screening mammography. Sixteen FFDM machines were used and the effective lifetime risk was calculated across the female lifespan for each machine. Once the risks were calculated using the phantom, the total effective lifetime risk across 48 national screening programmes was then calculated; this assumed that all these programmes use FFDM for screening. Results: Large differences exist in effective lifetime risk, varying from 42.21 [39.12-45.30] cases/106 (mean [95% CI]) in the Maltese screening programme to 1099.67 [1019.25-1180.09] cases/106 for high breast cancer risk women in the United States of America. These differences are mainly attributed to the commencement age of screening mammography and the time interval between successive screens. Conclusions: Effective risk should be considered as an additional parameter for the assessment of screening mammography programme performance, especially for those programmes which recommend an early onset and more frequent screening mammography. Keywords: Breast screening; Effective risk; FFDM; MGD; Thermoluminescence dosimetry.

Abstract Objectives Establish a method to determine and convey lifetime radiation risk from FFDM screening. Methods Radiation risk from screening mammography was quantified using effective risk (number of radiation-induced cancer cases/million). For effective risk calculations, organ doses and examined breast MGD were used. Screening mammography was simulated by exposing a breast phantom for cranio-caudal and medio-lateral oblique for each breast using 16 FFDM machines. An ATOM phantom loaded with TLD dosimeters was positioned in contact with the breast phantom to simulate the client’s body. Effective risk data were analysed using SPSS software to establish a regression model to predict the effective risk of any screening programme. Graphs were generated to extrapolate the effective risk of all screening programmes for a range of commencement ages and time intervals between screens. Results The most important parameters controlling clients’ total effective risk within breast screening are the screening commencement age and number of screens (correlation coefficients were −0.865 and 0.714, respectively). Since the tissue radio-sensitivity reduces with age, the end age of screening does not result in noteworthy effect on total effective risk. Conclusions The regression model can be used to predict the total effective risk for clients within breast screening but it cannot be used for exact assessment of total effective risk. Graphical representation of risk could be an easy way to represent risk in a fashion which might be helpful to clients and clinicians. Keywords Dosimetry Radiation risk Breast screening