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[en] PURPOSE: To evaluate the dosimetric characteristics of newly developed well-type ionization chamber and to compare the results with the commercially available calibrated well-type ionization chambers that are being used for the calibration of brachytherapy sources. METHOS AND MATERIALS: The newly developed well-type ionization chamber (BDS 1000) has been designed for convenient use in brachytherapy. The chamber has a volume of 240 cm3, weight of 2.5 Kg and the chamber is open to atmospheric conditions. The chamber characteristics such as leakage current, stability, scattering effect, ion collection efficiency, air-kerma strength and nominal response with energy were studied with the BDS 1000 well-type ionization chamber. The evaluated characteristics of BDS1000 well-type ionization chamber were compared with two other commercially available well-type ionization chambers. RESULTS: The measured leakage current observed was negligible for the newly developed BDS 1000 well-type ionization chamber. The ion collection efficiency was close to 1 and the response of the chamber was found to be very stable. The determined sweet spot was 42 mm from bottom of the chamber insert. The overall dosimetric characteristics of BDS 1000 well-type ionization chamber were in good agreement with the dosimetric characteristics of other two well-type ionization chambers. CONCLUSION: The study shows that the newly developed BDS 1000 well-type ionization chamber is high in sensitivity and reliable chamber for air-kerma strength calibration. The results obtained confirm that this chamber can be used for the calibrations of HDR and LDR brachytherapy sources. (author)
[en] Introduction. Despite the large number of recommendations the applicator insertion during HDR brachytherapy, a lot of questions regarding the choice and placement of the applicators, normalization and dose selection are still under discussion. Randomized trial comparing standard fractionation modes with other modes are not available. There are recommendations for the applicator types: they can be flexible or rigid, placed parallel to (French school) or “hand free”. Data taking into account are the follows: the volume of the tumor, histology and data from diagnostic tests. If the absence of invasion to regional lymph node are confirmed by different diagnostic tests we deliver monobrachytherapy. The aim of the study was to evaluate the efficacy of high local doses using HDR brachytherapy for lip squamous cell cancer. Materials and methods. 27 patients with histologically confirmed squamous cell carcinoma of the lower lip were treated in the department of radiation therapy from 2012 to 2016. According to US or CT data, regional lymph nodes were not invaded by the tumor. All patients underwent interstitial HDR brachytherapy with MicroSelectron (source 192Ir). Metal needles were inserted “hand free” under local anesthesia and were removed after each fraction. The geometry of needle spacing and the direction was dictated by the necessity to deliver maximal dose to the tumor. The number of needles varied from 2 to 7 depending on the tumor volume. The mandible was considered as a critical organ. A single dose was 8 Gy. Irradiation was carried out 2 times per week, total of 4 fractions. Irradiated volume ranged between 10 to 28 ccm. Treatment planning was carried out based on the 3D CT and with Oncentra treatment planning system. Graphical optimization was used. An example of a dose distribution is shown. Patients were examined every month during the first half off a year and every 3 month later. If necessary, the frequency of examination was increased. Results. Treated patients felt comfortable between the factions since the needles were extracted after each irradiation session. This reduces the risk of infection, which is often observed after insertion of flexible applicators. Short bleeding could happen just after the needles extraction but in few minutes it stopped. Swelling after the insertion of the needles usually disappeared in the evening of the same day of treatment. Radiation reactions lasted one month on average. New young tissue was formed under the crusts. No recurrence during period of observation was noted in all patients. Severe complications were also not noticed. Conclusion. 8 Gy per fraction, 4 fractions total, 2 times per week irradiation scheme for squamous cell carcinoma of the lower lip seems to be tolerant method of HDR brachytherapy allowing good local tumor control with reduced chance of infection. It significantly improves the patient’s well-being between the fractions. Radiation complications were not observed in this fractionation regime. (author)
[en] Purpose: Before a new calculation algorithm can be utilized clinically, a comprehensive evaluation is necessary. The accuracy of the dose calculated is very important for the quality and reliability of radiotherapy planning and delivery. The aim of the this study was to achieve an accurate calculation of dose for small fields(2x2,3x3) large field(7x7,10x10,20x20,25x25,30x30) and three asymmetric field dimensions Asymmetric 1 field (X1=-2,X2=5,Y1=-2,Y2=5) Asymmetric 2 field (X1=- 2,X2=5,Y1=1.5,Y2=1.5) Asymmetric 3 field (X1=1.5,X2=1.5,Y1=-2,Y2=5) by evaluating the accuracy of AAA calculations in the Eclipse Treatment Planning System with measurement. Material and Method: All the tested fields were calculated in the Eclipse treatment planning system(version 8.9.08) with AAA algorithms. A Varian Clinac 2100C/D accelerator delivering 6MV photons was used for all measurements in a blue Phantom 2 water tank. The CC13 detector was used for large field measurement whiles the A14SL detector was used for small and asymmetric field measurement. Determination of the physical factors required for dose estimation measured by the two ionization chambers and calculated by treatment planning system (TPS) were based on the latest technical report series (IAEATRS-398).The acceptability criteria used for the comparison of the calculated and measured data acquired were based on the report of the AAPM Task Group 53. Results: Good agreement between the measured and calculated dose were found, with the maximum difference not exceeding 1% for all fields. The highest difference between the calculated and measured data was seen in the large fields. The deviation in small fields, asymmetric fields and large fields were in the range of 0.0%-0.1%, 0.0%-0.3% and 0.1%-0.5% respectively. Conclusion: Since the accuracy desired in radiotherapy chain should mostly be less than 5% in dose delivery, the results from this study are well within tolerance and that the accuracy of AAA of Eclipse is adequate for clinical applications. (author)
[en] Introduction: Survival rate in cancer patients has increased in recent years and it is still growing. In these patients, there is a significant risk for developing a second primary tumor because of risk factors like genetic background, unhealthy behaviors or side effects from the therapy of first cancer. The goal of this study was to evaluate the frequency of incidence of different cancer types diagnosed in readmitted long-term survivors. An additional goal was to assess the risk for developing a metachronous cancer in patients with long-term survival. Methodology: From the patients admitted to the Oncology Institute, Cluj-Napoca,Romania, in 2014-2015,we selected only those patients who were first admitted to the same institute at least 5 years prior to 2014-2015. For these patients we evaluated the reasons of the first presentation, as well as those for the 2014-2015 readmission. Furthermore, we analyzed every case with metachronous tumor by considering the location of the first and second primary tumour. Results: Between 2014 and 2015 a total of 5080 cancer patients were admitted to the Oncology Institute Cluj-Napoca, Romania. 110 (2.17%) of these patients were first admitted more than 5 years ago. 25 (22.7%) of these 110 patients had no signs of oncologic disease, 21 (19.1 %) had a continuous disease progression, 20 (18.2%) had a relapse after a free disease period, and 44 (40%) had a second primary tumor. Median age in this group was 65, with a median survival of 12 years after the diagnosis of the first malignancy. The female to male ratio F : M was 1.3:1. In the men’s subgroup, head and neck cancers were found in 11 patients (23% of the cases), lung cancer in 7 (14.6%), central nervous system cancer in 5 (10.4%), and each of colon and urinary bladder cancer in 3 (6.3%) patients. In the women’s subgroup, breast cancer was diagnosed in 14 patients (23.3% of the cases), cervical cancer in 8 (13.3%), endometrial cancer in 7 (11,7%), ovarian cancer in 6 (10%), and each of head and neck and soft tissue cancer in 4 (6,7%) cases. In men with long-term survival (more than 5 years), 45% of those who were previously diagnosed with head and neck cancer developed in time a second primary cancer (5 of 11). Similar results for lung and prostate cancer patients were 28.5% (2 of 7) and 25% (2 of 8) respectively. None of the 5 cases of long term survivors of brain tumors developed second cancer. In the women’s subgroup, 12 of 14 (85%) of the patients who had breast cancer were diagnosed with a second malignancy. The corresponding data for cervical cancer was 4 of 8 (50%), for endometrial cancer 3 of 7 (42.8%), and for ovarian cancer 1 of 6 (16.66%).When common primary cancer sites are compared for both sexes, head and neck cancer was found to be significantly more frequent in men (23% vs 6.7%, p=0.01); for lung cancer it was (14.6% vs 3.3%, p=0.03) and for urinary bladder cancer it was 6.3% vs 0%, with a p value of p=0.05. Conclusion: 4 of 10 of the long-term survivors readmitted in the Oncology Institute were diagnosed with a second malignancy. In men, the most frequent first cancer was head and neck, and breast cancer was women’s most frequent malignancy. A comparison of common cancer sites for both sexes show the following: head and neck, lung and urinary bladder cancers were more common in men. Almost half of the men surviving for more than 5 years after being diagnosed with a tumor on the head and neck were diagnosed with a second cancer. The same situation was found for almost a third of the men who were previously diagnosed with lung cancer and a quarter of those who were previously diagnosed with prostate cancer. In women, the reason for readmission for 85% of the patients with breast cancer diagnosis more than 5 years ago was the occurrence of a second primary tumor. Cervical cancer and endometrial cancer also represented an increased risk (around 50%) of developing a new primary cancer. (author)
[en] Introduction. Advances in radiotherapy technologies have led to many benefits including better quality of treatments with potential less morbidity and survival improvement. These technologies, however, require not only more advanced equipment with higher costs, but also well trained human resources. In places where this technology is being implemented, qualified personnel is desired in order to properly start the treatment by itself. There is a lack of qualified personnel in our country regarding this subject. A Technical Cooperation Project (TCP) - “BRA/6/023- Supporting the Qualification of Human Resources in Advanced Radiotherapy Techniques” was, thus, developed with the IAEA including three reference centers in Brazil. The objective of the project was to provide personnel training in advanced technologies in radiotherapy such as Volumetric Modulated Arc Therapy (VMAT), 4D technology and Stereotactic Body Radiation Therapy (SBRT), and Image-Guided Radiation Therapy (IGRT). Overall, 17 professionals participated in specific trainings in international institutions during the period of the project, in 2012 and 2013. The objectives of this study were to evaluate and quantify the long-term results of this training. Methodology. A questionnaire with 22 queries was sent to all the 17 participants of the TCP - BRA/6/023. Training was performed through fellowships or scientific visits. The questions included demographic data, years of experience in the field, information about the specific training and the outcomes after the training program. Personal comments were allowed at the end of the questionnaire. Results. Seven radiation oncologists and 10 medical physicists were trained, seven male and 10 female. The mean age was 37, and the years of experience in the field ranged from 2 to 35 years, being the majority 3 years. The home institutions of the participants were Hospital das Clínicas of University of São Paulo, São Paulo, 48.9% (41.2% from the Cancer Institute – ICESP, and 17.7% from the Radiology Institute – INRAD); 35.3% from Hospital Sírio-Libanês, São Paulo, and 17.6% from Centro Infantil Boldrini, Campinas, respectively Training was performed in North American and European countries being 41.2% in the USA, 23.5%, Canada; 17.6% Germany; 5.9%, Netherlands; and 11.8%, others. The training activities started in July 2012 and finished in Nov 2013 being the great majority, 85.7%, a fellowship of one month period followed by 7.1%, for 2 months and 7.1% for 2 weeks (scientific visit) training, respectively. The topics of interest for training were VMAT: 52.9%, 4D technology: 47.1%, SBRT: 82.4%, and IGRT: 70.6%. Interestingly, besides the subjects directly related to the project, cranial radiosurgery (41.2%), brachytherapy (17.6%) and others (41.2%) were also referred as areas of having some training. Regarding the outcomes and contribution in the daily practice, 100% answered that they are using the training in their routine; and 82.4% helped in the training of other professionals in their institution, from 3 to more than 20 people. The knowledge was reported to increase in 100%. Development of a project in the host institution was possible for 41.2%, and 100% considered the training “Good” (35.3%) or “Excellent” (64.7%) and recommend the host institution to others. An increase in the use of the technology that was trained was reported by 88.2%. In their respective departments there was an increase of at least 50% in the use of more advanced technology with improvement of the processes in 76.5%. Among the general comments, besides the improvement of the professional skills, comments about the opportunity to interact with experienced professionals and “keeping in touch” with them, to have an overview of the Radiotherapy Departments’ routine, and to interact with another culture in a different language were the highlights. “The training was for me one of the best experiences that I had in my professional life”. Conclusions. The TCP BRA/6/023 has enabled the upgrade of a good number of physicists and radiation oncologists from the centers. The implementation of new technologies was better supported with the training program, and, at the same time, the knowledge was shared and transmitted to other professionals. Overall, the training program was considered an excellent type of training by all the participants, and after almost three years, the use of the technology in the participating centers was increased in at least 50%. (author)
[en] The description of the design of a lower resolution hybrid silicon pixel detector, designed specifically for the purpose of continuous spatial on-line dose monitoring during the whole treatment. (author)
[en] Introduction: As in any field, errors happen in radiation oncology despite our best efforts to prevent them. It is well known, and well documented, that appropriate, adequate training can reduce the likelihood of errors.. The World Health Organization (WHO) published the manual Radiotherapy Risk Profile in 2008 and in this manual it lists competency assessment as one of the top three interventions that is likely to be an effective safety barrier. But what is competence? Competence is the ability to do something successfully and efficiently. Hence, competency based education and training must offer comprehensive training as well as be able to determine whether an individual can successfully complete a task independently and do so in an efficient manner. Radiation oncology is a technology centered specialty that is continuously evolving and requires continued education and training to stay up to date with current technology, improved techniques, and/or to increase efficiency as well as improve overall safety. Methodology: An online system was setup in order to establish specific training modules and track users’ progress throughout their competency development. Various media was used to convey information to users such as text files, presentation slides, and videos. Additionally, certain modules included quizzes based on educational material as well as assigned clinical observations where an individual would be followed and assessed in the clinic for a particular procedure. To test which media was most effective at communicating information, members of the department of radiation oncology was randomly assigned to 1 of two groups. Each group was assigned a general radiation safety module, where one group’s assignment was text/slide based and the other group’s assignment was video based. Each group had the same quiz administered after the content was reviewed. Additionally, brachytherapy modules were given to new medical physics residents with no prior brachytherapy experience. Program compliance and overall assessment was measured and residents were surveyed about the program. Results: The online system was deployed in the department with various module assignments given to specific groups. Various metrics were measured including program compliance, individual assessment after the program (competence), and survey feedback from users and will also be discussed. Conclusion: An online competency based education system utilizing multimedia content, along with hands on assessment, is an efficient and effective tool to implement in radiation oncology. (author)
[en] Introduction: In the present day Medical physics is one of the most demanding and rewarding applications of physics in society. As a professional, Medical Physicist who works in the hospital environment is a member of a wide clinical team which is responsible for the accurate diagnosis and the therapeutic methods applied using radiation. Medical physics activities in country: The Medical physics activities originated in Bangladesh at 1954 where the first X-Ray machine was established in Kumudini hospital. The first Radiotherapy department was set up at 1957 in the same hospital and in 1960 the first Nuclear Medicine Centre was established in Dhaka Medical College Hospital (DMCH). At present, there are 20 Nuclear Medicine facilities in different part of the country. Under these facilities, 45 Gamma Camera/SPECTs and 5 PET/CT were installed. There are 28 Radiotherapy centres in our country where 19 linear accelerators, 8 CT-Simulators, 9 Tele-Cobalt machines and 13 Brachytherapy units have been equipped. Around 5000 X-ray unit and 150 CT have been installed in our country so far. Medical physicist in Bangladesh: Around 60 Medical Physicists are working in all radiation oncology establishments and 19 Medical Physicists are working in all Nuclear Medicine departments. 150 millions people’s country of Bangladesh, we need around 300 radiotherapy centres and 600 medical physicists in oncology but we have achieved very little. Medical Physics education in the country: In Bangladesh there are 37 public and 92 private universities, however, they offer limited courses on medical physics. A few courses offered by the public universities cover some aspects of medical physics, while only one private university, Gono Bishwabidyalay (University) has a B.Sc and M.Sc degree program under the full faced Medical Physics and Biomedical Engineering Department. Research work in Medical physics was started in Department of Physics, University of Dhaka at 1978 and first M.Sc. student started thesis work in Medical Physics in the same department in 1981. Inception of Medical Physics courses in M.Phil. and Ph.D levels started in Bangladesh University of Engineering & Technology (BUET) under the division of Health & Medical Physics in 1982. In 2008 University of Dhaka (DU) opened a new Department of Biomedical Physics and Technology offering M.Phil. and Ph.D program. In 2014, DU has started MS program in Medical physics. Clinical training in hospital: The university programs are however not coupled with appropriate clinical training, making these curricula inadequate for practical clinical application. Under the MS program in DU, students are going for only 3 months internship in radiotherapy and nuclear medicine. Structured clinical in-service training program for medical physicists are also not sufficient. Hands-on-job training or training at home and abroad are the main sources of clinical medical physics learning. Clinical training supported by IAEA: International Atomic Energy Agency (IAEA) has developed three clinical training program guide books for medical physicist in the fields of Radiation Oncology, Diagnostic Radiology and Nuclear Medicine. This was done under a Regional Cooperative Agreement (RCA) program on strengthening of medical physics through education and training. In 2011, Bangladesh commenced the first pilot clinical training program of medical physics in nuclear medicine based on the IAEA’s training course. Under this program 4 medical physicists successfully completed the clinical training.
[en] The population of Bangladesh is estimated about 160 million living on an area of 143,998 km2, the number of cancer patients equals 2000 out of 1,000,000 inhabitants per year. According to WHO, we need total 160 Centers, 320 LINACS, 640 Medical Physicists and even more considering diagnostic radiology and nuclear medicine centers. Medical physics study in Bangladesh is gaining importance day by day as cancer treatment is entering a new era from conventional to conformal therapy technique. In Bangladesh, all Nuclear Medicine Centers are under Bangladesh Atomic Energy Commission (BAEC), so they recruit physicists in the position of scientific officer and undergone training in these fields under IAEA. In this way medical physicists in the nuclear medicine area are developed but medical physics in radiotherapy and x-ray diagnosis is poorly developed. Germany play the pioneer role in the development of medical physics in Bangladesh. The commencement of Medical Physics education in Bangladesh has started mid 90s by Bangladeshi German professor through different seminars, workshops organized by “Medical Physics in the Developing Countries” of the German Society for Medical Physics (DGMP). As a consequence, medical physics study established in 2000 in the department of Medical Physics and Biomedical Engineering (MPBME), Gono Bishwabidyalay (GB) with collaboration of Heidelberg University, Germany. The purpose of this study is to produce medical physicists and biomedical engineers especially for the radiotherapy hospitals, diagnostics center, universities. Later, two more universities started this study at MSc level in 2014.
[en] Introduction Although the effect of ionizing radiation in biological systems depends not only on the applied dose, but also on the used energy, dose rate and filters, these parameters are often neglected during radiation therapy. Peripheral blood lymphocytes were irradiated in vitro with a Varian TrueBeam linear accelerator and chromosomal aberrations were analysed in this biological dosimetry study using the linear-quadratic model. Samples were irradiated either with different energy levels or with different dose rates, then dose-reponse curves were compared. The differences in dose-response effects between gamma photons and kV photons were also studied. Our goal was to identify the potential, substantial variations between different therapeutical scenarios and to explore the limits of the linear-quadratic model. Materials and Methods Venous blood sample was obtained by venipuncture from 22 healthy volunteers into Li-heparinized vacutainers. Blood samples in 2 ml cryotubes were positioned in a water filled plastic phantom in order to achieve homogenous doses. Samples were positioned in the isocenter. Irradiation was conducted with different dose rates as follows: 80, 300, 600 MU/min with 6, 10, 18 MV photon beams and 400,1600, 2400 MU/min at doses between 0.5 and 8 Gy at room temperature. Flattening Filter free (FFF) mode was also studied at 6 and 10 MV. Metaphases from lymphocyte cultures were prepared by standard cytogenetic techniques: 0.8 ml blood was added to 9 ml RPMI-1640 cell culture medium containing 15 % bovine serum albumin and penicillin/streptomycin (0.5 ml/L). Lymphocyte proliferation was induced with phytohaemagglutinin M (0.2%). Incubation time was 50-52 hours at 37°C. Cell proliferation was inhibited with 0.1 mg/ml colcemid (Gibco) in the last 2 hours of culturing. Cell cultures were then centrifuged and hypotonized with 0.075 M KCl for 15 minutes at 37°C, then cells were fixed with cold methanol-acetic acid 3:1 mixture. The cells were dropped on glass slide, and stained with 3% Giemsa. Chromosome analysis was performed in the first cell division, and a minimum of 100 metaphases were scored. All aberration types were recorded: aneuploidy, chromatid and chromosome fragments, exchanges, dicentrics, rings and translocations. Alpha (a) and beta (b) values were calculated for all dose-response curves. Results At lower doses (1-2 Gy) acentrics (not to be confused with the dicentrics or rings coupled fragment) exceeded the number of dicentrics, however, at higher doses this tendency reversed and dicentrics predominated. However, as photon energy increased (at the same dose rate) aberration frequency tended to decrease, i.e. lower energy caused more aberrations. The a coefficient of doseresponse curves was negligibly small, the b quadratic values dominated. The effect of conventional irradiation technique with Flattening filters and intensity modulated radiation therapy mode (FFF) on chromosomal aberrations were also compared. The highest values were as follows: 533 aberrations/100 cells (318 dicentric + ring chromosomes) at 8 Gy, 6 FFF, 400 MU/min. Two Gy dose fractions induced 14 0.9 dicentrics and 29 1.6 all aberrations in 100 cells. Conclusion The effect of 2 Gy dose fractions on chromosomal structure was almost identical at different energy levels and dose rates. However, higher aberration rates were found between the applied modalities when larger fraction doses were used. These results might be important in the case of hypofractionated radiotherapy and radiation incidents. (author)