ABSTRACT
In this study the basic radiation properties of N-isopropylacrylamaide polymer gel dosimeter were determined together with verification of its soft tissue equivalency. The NIPAM gel was prepared and irradiated approximately 2 h after manufacturing. The magnetic resonance [MR] images were made 24 h after irradiation. The nuclear magnetic resonance [NMR] response [R2] of the dosimeters was analyzed for conditions of varying dose, batch, dose rate, time post-irradiation and energy. In order to verify tissue equivalence of NIPAM dosimeter, several parameters such as physical density, effective atomic number, relative electron density, CT [Computed Tomography] number and also elemental composition were determined and compared with those for soft tissue. The response of the gel was found to be stable 24 hours after irradiation. The results showed that the dose response of the NIPAM polymer gel is reproducible in same and different batches of chemical and the gel response was linear up to 26 Gy with r2=0.995. In the measured range, the dose response of the NIPAM gel is independent of beam energy within less than +/- 0.02 and the dose rate had no effect on the gel response. This polymer gel has been found to be tissue equivalent. NIPAM gel dosimeter appears to be a promising dosimeter in all aspects of dosimetric properties which were assessed in this study, in addition to the advantage of reduced toxicity which it has over other polymer gels
ABSTRACT
Accuracy of the delivered dose to the patient is one of the most important and effective factors in radiotherapy. In vivo dosimetry is used to evaluate the accuracy of delivered dose in radiotherapy. Therefore, in this study the accuracy of delivered dose to the patients was verified using in vivo dosimetry in radiotherapy department of Tabriz lmam Hospital. Entrance doses of 320 fields treated by Cobalt-60 machine and linear accelerator including head and neck, trunk, pelvis, and extremities were measured using in vivo dosimetry system. Difference between measured entrance dose and prescribed dose for each field was determined. For all fields and also for each specific group of fields, average error and standard deviation of its distribution were determined. For whole fields, the average error of 1.34% with standard deviation [SD] of 7.12%, for [60]Co fields the average error of -0.17% with SD of 5.98% and for Linac fields, the average error of -3.56% and 7.17% were seen. In head and neck fields, the average error of -0.37% with SD of 4.73%; for trunk fields the average error of%-1.88 with SD of 7.27%, and for pelvis and extremities, the average error of -2.49% with SD of 7.79% were seen. The results show an acceptable systematic error in radiotherapy department. But standard deviation of 7.12% is slightly higher than the recommended value of 5%. It is possible to lower the uncertainty in delivered dose to recommended value by optimization of Linac function, regular quality control, and workload reduction
Subject(s)
Humans , Quality Control , HospitalsABSTRACT
Research in medical science, as in all other fields of science, is necessary in order to maintain and improve the public health. This is achievable only by researchers and faculty members. This study is attempt to identify intra-organizational factors that influence research planning and related interventions in Tabriz Medical University. In this descriptive cross-sectional study, the study group included all faculty members and masters of science [equivalent to faculties] in Tabriz Medical University, of which 121 persons were selected randomly. Lickert style questionnaires were developed to evaluate and compare the attitudes toward project approval process, knowledge about research facilities, departmental cooperations in research, and researchers' capabilities in project execution. Data analysis was performed using SPSS software. During a 3 year period, each faculty member had, on average, supervised 5.17 dissertations, conducted 1.15 approved research projects, and had 3.4 presentations in domestic and 0.36 presentations in international conferences. Lack of time was the main problem in conducting research. Comparing faculties with and without research experience, there was significant differences in regard of access to research facilities [p<0.01], assessment of the benefits of research [p<0.02], and the level of research knowledge [p<0.02]; while no significant difference was found regarding motivations, job satisfaction, departmental cooperation, and expecting benefits from conducting research. According to the faculties' views, intra-organizational problems are less important than personal factors in performing research projects; i.e. the main obstacles for research were lack of time, and lack of competence in research methodology and problem-finding. Intra-organizational factors such as delay in project approval and lack of knowledge about research priorities are classified in the next levels