42 treatment different segments of the treatment field can be exposed to the primary beam for different intervals of time. This process of shrinking the field while modulating the collimator jaw velocity and dose rate creates the desired wedge-shaped iodose gradient across the treatment field. Dynamic wedges can replace physical wedges but their need more precise dosimetry and quality control procedures. The dynamic wedges are realized by continuous movement of one collimator jaw. The field size is gradually reducing until the collimator is almost completely closed or the field is increasing, while the beam is on. The measurements were divided in two steps: in the first step there were verified the dynamic wedges with the recommended values and in the second step there were compared the planned and measured angles of dynamic wedges. Measurements were made by means of LA48 linear array of ionization chambers (PTW). Methods: The measurements were performed for Clinac 2300C/D accelerators (Varian) by using LA48 linear array of ionization chambers (PTW) for 6MV and 15MV photon beams. There were verified the dynamic wedges with the recommended values and compared the planner Results: For energies 6MV and 15MV almost all percentage difference between measured and calculated profile was smaller than 5%. The biggest difference were observed in the first step of measurements when the angle of Dynamic Wedge was verified. The comparison between the planned and measured angle value of Dynamic Wedge showed the difference between 0,1 % - 4,5%. It is neccessary to provide comprehensive quality control procedure for enhanced dynamic wedges. 15.2. Brachytherapy Treatment of cervical Cancer: A Comparision of two centres in Africa Presenter: Longino Mucheusi, Kenyatta National Hospital & Kenya Medical Training College, Kenya Author: Longino Mucheusi, OGW Introduction: Brachytherapy treatment of cervical cancer: A comparison of two centres in Africa. By Longino Mucheusi, RTT Training Coordinator Kenyatta National Hospital & Kenya Medical Training College, Nairobi, Kenya Abstract Background and Purpose Brachytherapy plays an essential role in the management of patients with cervical cancer. This study analysed treatment outcomes of two brachytherapy modalities, high dose rate (HDR) and low dose rate (LDR) intracavitary treatment for patients with cervical cancer at two Centres in Africa. The aim was to determine how well HDR compared with LDR intracavitary brachytherapy (ICBT), given the problems and challenges that exist on the African continent. Methods: Materials and Methods Treatment outcomes of one site treating with HDR and the other LDR ICBT were retrospectively analysed for 193 patients in the HDR group and 49 patients in the LDR group. All patients were treated with external beam radiation therapy Results: Results The findings showed several issues in regard to clinical outcomes between patients treated with HDR and LDR at the two Centres. The median follow-up for patients treated in the two groups (HDR and LDR) was 42.2 and 12.4 months, respectively. The actuarial 5-year pelvic relapse free survival in the HDR and LDR group was 65.8% and 53.9% (p = 0.84), respectively. The 5-year bladder and rectal (grade 3 and 4) complication rates for patients treated with HDR were 3.4% and 3.0% 15.3. Gantry Speed of Cone Beam CT (CBCT) and Patient's Breathing Rates for Three-Dimensional Setup of Lung Tumor Motion in Radiotherapy Presenter: Utumporn Duanganan, (Radiation Technology), Mahidol University, Chulabhorn Hospital, Bangkok, Thailand Authors: Utumporn Duanganan, Chirapha Tannanonta, Sangutid Thongsawad, Chirasak Khamfongkhruea, Rattanaporn Siricha Introduction: Radiation treatment of lung cancer is complicated because of tumor moving with patient respiration. Four-dimensional CT (4D-CT) imaging is needed for accurately tumor contouring and reducing margin. For accurate patient setup, onboard cone-beam computed tomography (CBCT) imaging is currently used. The image reconstruction of the 4D-CT with average intensity projection (AVG) is preferable for using as the reference in registration with CBCT images comparing with the other methods, maximum intensity projection (MIP), Mid Position (MidP), and free breath. Since 4D-CBCT is not available with our machine, free breath CBCT (FB-CBCT) is used for registration. From our data, the patient breathing rate ranged from 10 - 21 bpm (breaths per minute). The gantry speed of our machine can be varied with 3 steps, 3°/s, 4°/s and 6°/s. The purpose of the research was to determine the appropriate gantry speed of FB-CBCT for each breathing rate. Methods: The 4DCT of a Respiratory Motion Phantom with RPM was done. The reference AVG image was matched with CBCT’s. From the matching of the images, the targeting accuracies were analyzed by using both shifting distance and matching Index, MI methods. Results: The shifting distance method for every breathing rate with each gantry speed from every observer shows the same errors for all directions with the values of 0.1, 0, and -0.1 cm for AP, SI, and LR respectively. The value of MI for every breathing rate with each gantry speed was close to 1 so that the gantry speed does not effect the targeting accuracy of CBCT. For decreasing the scanning time and radiation dose to the patient, the high gantry speed is preferred. 15.4. To contribute to human resource capacity building in comprehensive cancer control in the African Region by establishing a Virtual University for Cancer Control (VUCC) supported by a Regional African Cancer Training network (RACT network), collectively called VUCCnet Presenter: Susan Morgan, International Atomic Energy Agency Author: Susan Morgan There is a drastic shortage of accessible knowledge and quality training programmes in Africa for comprehensive cancer control. In particular, local capacity to train and mentor practitioners within the region is not sufficient to ensure sustainable cancer control and to counter the effects of brain drain. Combined with a lack of financial resources, this scarcity of training opportunities has resulted in a great shortage of trained professionals in health care, particularly in cancer control and treatment. PACT Programme Office, in cooperation with its international partners in cancer control and experts in radiation medicine within the IAEA, has developed a project to address this shortage. This initiative, collectively referred to as VUCCnet, is intended to support and enhance Member States’ programmes to build human resource capacity in cancer control. The VUCCnet initiative will help establish training and mentorship networks within and amongst low and middle income (LMI) countries, while building a web-based platform to make educational materials more easily accessible to and affordable for trainees. Through the VUCCnet, it is anticipated that trainees will have access to learning materials that can be used at their own pace, either alongside other course work, or as a means for practicing health care professionals to refine or update their knowledge base. The VUCCnet model also aims to allow for more trainees to partake in cancer control training, directly affecting the number of health care professionals available in participating Member States. 15.5. Implementing new clinical procedures in an overburdened healthcare system, at Ho Chi Minh City Oncology Hospital, Vietnam Presenter: Vu Huynh, HCMC Oncology Hospital, Vietnam Author: Vu Huynh Introduction: Ho Chi Minh City (HCMC) Oncology Hospital is the largest Radiation Oncology Centre in Vietnam, treating many patients from all around the region. For Vietnam, cancer is a leading cause of mortality. Radiation Therapy continues to play an essential role in cancer control, in both treatment and palliation. Over the last decade, Vietnam has come a long way in terms of Radiation Therapy services. In 2000, the country installed its first linear accelerator. Previous to this, Vietnam was using a small number of Cobalt 60 units which derived from the Soviet Union in the 1970s, followed by World Vision Australia and the French Government in the 1990s. Within recent years Vietnam has seen a rapid growth in the number of linear accelerators installed due to government and private sector initiatives. But this is still not enough to cope with the overwhelmingly large patient loads, as the majority of cancer treatment resources lay in developed countries, even though the majority of sufferers live in developing countries. To cope, some treatment machines are only given a small break daily, working in shifts to provide radiation treatment 20-23 hours a day. Hospitals are severely overloaded serving four to five times more patients than intended capacities. And to add pressure, these statistics are set to worsen at a much faster rate compared to developed countries. Current plans to expand oncology along with the Vietnamese government’s aim to raise technical skills will mean a major
ISRRT | Book Of Abstracts
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