Potential radiosensitisation of breast- and lung cancer cells by a novel anti-mitotic oestrone analogue

Abstracts/Physica Medica 31 (2015) S15–S21

Conclusion: Iterative reconstruction proved to increase image quality by a substantial increase in SNR and a reduction in image noise. Keywords: Image quality, Radiology, CT

P.8 BREAST ENTRANCE EXPOSURE AND AVERAGE GLANDULAR DOSE: OBSERVER PERFORMANCE STUDY D Mashalane * ,a, H.L. Tlhapi b. a Department of Medical Physics, Sefako Makgatho Health Sciences University, Pretoria, South Africa; b Department of Diagnostic Radiology, Dr George Mukhari Academic Hospital, Pretoria, South Africa Introduction: The objective of this study was to measure the breast entrance exposure and to calculate the corresponding glandular dose for an average patient with approximately 4.5 cm compressed breast thickness of 50% adipose. Materials and Methods: The materials used included a Selenia Lorad digital mammogram machine, phantom of 4.5 cm thickness, a 24 × 30 cm compression paddle with a compression device and a PTW ionisation chamber. The ACR Phantom was centred laterally on the image receptor and it was positioned such that the chest wall edge of the phantom was aligned with the chest wall edge of the image receptor. The ionisation chamber was positioned in the X-ray field besides the ACR phantom, centred 4.0 cm in from the chest wall of the image receptor and the centre of the chamber levelled with the top surface of the ACR phantom. The compression paddle was placed above the phantom and chamber to achieve a compression thickness of 4.5 cm. The system was set in the AEC mode, with the compensation step of 0 and AEC sensor position 2. Large focal spot was selected with molybdenum filter and 28 kVp. Results: Four exposure measurements were taken for analysis: 2.37 mGy, 2.37 mGy, 2.41 mGy and 2.40 mGy, and the standard deviation of 0.0016 was obtained yielding a covariance of 0.01. The average glandular dose was calculated using the equation: AGD = f × r and it was 0.39 mGy. Conclusion: This study was done according to the manufacturer’s specifications of the dose measurements in mammography units. The results were within the recommended criteria for imaging an average breast. Keywords: Mammography, Glandular dose, Compression paddle, ACR phantom

P.9 CONCRETE DENSITY ESTIMATION OF GROOTE SCHUUR HOSPITAL LINEAR ACCELERATOR BUNKER WALLS USING IMPACT ECHO TESTING F. Moosa *,a, H. Burger b, C. Trauernicht b, G. Blassoplesc c, E. Okwori d, B. Nyoni d, P. Moyo d. a Department of Medical Physics, Groote Schuur Hospital; b Department of Medical Physics, Groote Schuur Hospital and University of Cape Town; c KFD Wilkinson Consulting Engineers, Cape Town; d Department of Civil Engineering, University of Cape Town Introduction: Groote Schuur Hospital constructed a new radiotherapy bunker for a high-energy linear accelerator. During construction areas of honeycombing became evident in the concrete. Honeycombing reduces the density of concrete and may affect the shielding integrity of the walls. Since the linac had not yet been installed, the radiation beam could not be used for testing, and an alternative non-destructive testing method had to be employed. The aim of this study was to use the impact-echo technique to verify the wall integrity. Materials and Methods: In this method, a mechanical impact is used to create stress waves, which propagate through the concrete and are reflected or refracted where there are changes in material characteristics such as density. In theory, non-visible honeycombing at depth will present multiple reflection surfaces and should result in a broad-band response with multiple small peaks. The propagation of the stress wave is dependent on the elastic modulus, density and Poisson’s ratio of the material. Radiation measurements at the same positions on the walls where impact echo testing was performed will be completed with the 6 MV linear accelerator once installed, and the data extrapolated for 18 MV photon beams as per bunker design.

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Results: The impact echo results show that the density of the primary barriers ranged from 2.30 g/cc to 2.55 g/cc for the one wall, and from 2.20 g/ cc to 2.45 g/cc for the other primary barrier. However, testing showed a possible localised void in one of the walls. Core drilling at that point to a depth of 1 m showed no evidence of a void. Conclusion: The final results on whether the primary walls offer adequate shielding will only be confirmed once the linear accelerator is functional. The impact-echo testing results and radiation survey results will be correlated. Keywords: Impact-echo, Shielding, Honeycombing, Radiotherapy, Non-destructive P.10 COMPARISON OF TWO DIFFERENT CELL CYCLE PROLIFERATION ANALYSIS METHODS USING BrdU X. Muller *, J. Slabbert. Department Radiation Biophysics, NRF-iThemba LABS, Somerset West, South Africa Introduction: The extent of cellular radiation damage is dependent on the stage of the cell cycle and new methods to determine this are frequently being developed. Here we used bromodeoxyuridine (BrdU) that is incorporated into newly synthesized DNA and is detected using an immunofluorescent anti-body. This method aims to quantify the fraction of cells in S-phase as BrdU acts as a thymidine analogue. The advantages of using BrdU are that it allows for the identification and analysis of actively cycling cell fractions and also permits the determination of cell cycle kinetics. The aim of this study was to compare S-phase fractions observed using flow cytometry with microscopy methods. Materials and Methods: Isolated lymphocytes were given 0 Gy and 2 Gy doses of cobalt-60 gamma rays. PHA stimulated cells were cultivated for 45 hours and then either pulse labelled for 15 minutes or incubated for 1 hr in medium containing BrdU. Non-stimulated lymphocytes were labelled concurrently and used as negative controls. Counterstaining using a BrdU antibody was done using separate protocols for flow cytometry and microscopy. Results: A slightly higher percentage of S-phase fractions could be detected using flow cytometry (23% for 15 minute and 33% for 1 hour labelling) compared to microscopy analysis 21% for 15 minute and 30% for 1 hour labelling). Conclusion: Flow cytometry is the preferred method to quantify S-phase cell fractions. Microscopy based analysis is more tedious and has a greater risk of human error. Keywords: Bromodeoxyuridine, S-phase, Cell cycle kinetics P.11 POTENTIAL RADIOSENSITISATION OF BREAST- AND LUNG CANCER CELLS BY A NOVEL ANTI-MITOTIC OESTRONE ANALOGUE E.M. Nolte *,a, R. Lakier b, A. Van Rensburg b, J.M. Helena a, M. Verwey a, A.M. Joubert a, A.E. Theron a. a Department of Physiology, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa; b Department of Radiation Oncology, Steve Biko Academic Hospital, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa Introduction: Breast- and lung cancers are among the most frequently diagnosed cancer types in South Africa. 2-Methoxyestradiol was reported to sensitise prostate cancer cells to radiation therapy. The aim of this in vitro study was to determine whether a low dose of an in silico designed 2ME analogue 2-ethyl-3-O-sulphamoyl-estra-1,3,5(10),15-tetraen-17-ol (ESE15-ol) pre-exposure increases the sensitivity of breast- and lung cancer cells to γ-radiation. Methods and Materials: Dose–response curves using Annexin-FITC were used to determine the concentration of drug and dose of γ-radiation at which apoptosis was first detected. Morphological studies included light- and transmission electron microscopy. Clonogenic studies were done by allowing colony formation for 7 days after radiation. Flow cytometry was used for apoptosis detection, cell cycle analysis, Bcl-2 signalling effects, as well as reactive oxygen species production (superoxide). Effects on epigenetics were determined by flow cytometry analysis of histone deacetylase (HDAC) 1

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Abstracts/Physica Medica 31 (2015) S15–S21

and HDAC 6. Autophagy induction was detected via monodansylcadeverine fluorescence and quantified by flow cytometric detection of microtubuleassociated protein 1A/1B-light chain 3. Results: Pre-exposure of cells to nanomolar concentrations of ESE-15-ol for 24 hours prior to γ-radiation (6 Gy) resulted in detectable differences in the cell morphology compared to drug- and radiation exposure individually. An increased number of cells in late apoptosis and in the sub-G1 phase confirmed microscopic observation. Clonogenic studies revealed a significant decrease in colony formation. Flow cytometry indicated increased superoxide production, as well as decreased Bcl-2-phosphorylation. An increased number of vacuoles, indicative of autophagy, were observed in cells pre-exposed to the compound before radiation. Conclusion: Pre-treatment of MCF7- and A549 cells with ESE-15-ol sensitized cells to γ-radiation and induced programmed cell death more so than ESE-15-ol- or radiation-exposure alone. Future studies will investigate the effect of ESE-15-ol-pre-exposure on DNA damage and DNA repair mechanisms induced by γ-radiation. Keywords: Cancer, Radiation therapy, ESE-15-ol, Radiosensitisation, Apoptosis

relative intrinsic error was within 2%. The expanded uncertainties of measurements at 95% level of confidence were not more than 3%. Conclusion: Most of the results met the IEC-161676 performance requirements except the maximum intrinsic error which was above the set limit of ±1 kV, hence a deviation of the calibration factors in mammography beam qualities. It was difficult to confirm if this deviation was due to the intrinsic limitations of Piranha. Nevertheless this observation indicates the importance of traceable calibration of the non-invasive device. Keywords: Potential divider, Practical peak voltage (PPV) and traceability P.14 OPPORTUNITIES ARISING FROM THE QUANTITATIVE IMAGING NETWORK FACE-TO-FACE MEETING, BETHESDA W.I.D. Rae *. University of the Free State, Bloemfontein

Introduction: The Integral Quality Monitor (IQM) is an independent realtime treatment verifying system which validates the integrity and accuracy of the treatment plan data. The IQM also functions as a pretreatment quality assurance tool for radiotherapy. The IQM is essentially a large ionization chamber that is fixed to the treatment head of the Linac. The aim of this study is to model this device for Monte Carlo simulation purposes. Materials and Methods: The ionization chamber is made of metallic electrode plates in an insulating material frame. The center electrode serves as the collecting plate covered by the gradient plates. An MLC Linac was built using BEAMnrc with the IQM model attached to it. The integral dose was evaluated for different MLC settings to detect its sensitivity. Results: The Monte Carlo model of the IQM was built using the IQM component module of BEAMnrc. The dose scored for different MLC settings increases with an increase in field size. Conclusion: The EGSnrc Monte Carlo code successfully modeled the IQM and scored the dose in the IQM that will also be utilized to carry out further research on the IQM. Keywords: Integral quality monitor (IQM), Monte Carlo, Dose

Introduction: During late 2014 the South African Institute of Physics (SAIP) made contact with various bodies in the United States of America (US) including the National Cancer Institute (NCI) and interest was expressed in establishing some collaboration in research and training to stimulate Biophysics and Medical Physics activities in South Africa (SA). Thus three SA participants were invited to attend the annual Quantitative Imaging Network (QIN), Face-to-Face meeting, held April 13–14, 2015, in Bethesda, US. Two University of the Free State (UFS) delegates attended. This presentation offers feedback and collaboration possibilities. Materials and Methods: This is an observational study. Data were collected before, during and after the QIN Meeting. Results: The QIN is funded by the NCI. They actively stimulate quantitative imaging in cancer research. Research results and fields presented during the QIN Meeting highlighted many points of contact with the quantitative imaging done in nuclear medicine, radiology and radiotherapy physics at the UFS. There is a current funding program announcement for PAR14–116.html. The Scientist Exchange Program (STSEP) of the Centre for Global Health supports in part exchange visits between US and foreign laboratories. Guidelines for achieving Associate or Full Membership of the QIN were made available. Grant funding and collaboration are required. A document, suggesting a possible way forward, has been drawn up for Biophysics in SA. Conclusion: The meeting allowed direct contact and made the NCI and QIN aware of our capacity and possibilities for collaboration. Several funding and collaboration possibilities have been identified, but there are no opportunities for direct funding of student projects. There is strong support for our research and training initiatives and this should be utilized if possible. Keywords: QIN Meeting, Quantitative imaging

P.13 CALIBRATION OF NON-INVASIVE KVP METER TRACEABLE TO VOLTAGE MEASUREMENT STANDARD

P.15 THE INFLUENCE OF AGE ON CHROMOSOMAL RADIOSENSITIVITY OF SOUTH AFRICAN BREAST CANCER PATIENTS

P.12 MONTE CARLO STUDY OF AN INTEGRAL QUALITY MONITORING SYSTEM O.M. Oderinde *, F.C.P. du Plessis. Department of Medical Physics, University of the Free State, Bloemfontein, South Africa

R. Pepenene *, S. Jozela. Ionising Radiation Laboratory, National Metrology Institute of South Africa, Pretoria, South Africa Introduction: The assessment of X-ray tube voltage is essential to ensure optimal image quality. A non-invasive voltage measurement method is preferred since it can be done using more convenient instrumentation. In this study a new measurement capability for calibrating non-invasive devices against a voltage divider is presented. Materials: Constant potential generator, Beam qualities: conventional x-rays (RQR-2 to RQR-10) and Mammography (RQR-M3 and RQR-M4), Calibrated frequency compensated high-voltage divider, Calibrated multimeter) and Piranha R&F/M 657. Methods: The PPV of the tube was measured invasively from a high voltage divider using a multimeter. The mammography beam qualities were measured at a distance of ±40 cm from the focal spot, the distance was not critical for the conventional diagnostic radiology measurement. The calibration factors were determined from the ratio of the invasive and the noninvasive PPV values. Results: The calibration factor for the piranha ranged from (0.982–0.999) to (0.944–0.949) for conventional and mammography beam qualities respectively. The maximum intrinsic error was more than 1 kV and maximum

T. Smith *,a,b, F.Z. Francies a,b, O. Herd a,b, A. Cairns c, J.P. Slabbert a, A. Baeyens a,b. iThemba LABS – NRF, Somerset West, South Africa; b Radiobiology, Department Radiation Sciences, University of the Witwatersrand, Johannesburg, South Africa; c Surgery, WITS Donald Gordon Medical Centre, Johannesburg, South Africa a

Introduction: The leading cancer amongst women on a global scale is breast cancer. The disease is caused by numerous factors such as family history, hormonal factors as well as environmental influence and lifestyle. One of the treatments available for breast cancer patients in South Africa is radiotherapy. Chromosomal radiosensitivity is an increased vulnerability of cells to the DNA-damaging effects of ionising radiation and has been used as an indirect measure of cancer susceptibility. A recent study in our group has shown South African breast cancer patients to be more sensitive to ionising radiation than healthy individuals. The aim of this study is to investigate the influence of age on chromosomal radiosensitivity in breast cancer patients by using the micronucleus (MN) assay. Materials and Methods: Heparinised blood of breast cancer patients and healthy controls was irradiated in culture medium at doses of 2 and 4 Gy. Lymphocytes were stimulated by the addition of phytohaemagglutinin. Cytokinesis block was achieved by the addition of cytochalasin B 23 hours later and the cultures were harvested 70 hours later. The cultures were then