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Background: image processing is the key in planning external beam radiotherapy treatments. In its execution, human errors and equipment failures can occur, which lead, among other effects, to erroneous interpretations of diagnostic images, target contouring errors, overdose of healthy tissues or underdose of tumor tissues, which means putting patients at risk patients subjected to these practices. Objective: to characterize the risks associated with technological and human factors related to image processing that can affect patients undergoing radiotherapy treatments with external beams. Methods: intensity modulated radiotherapy was used as the basis of the study. To characterize the initiators and defense measures related to this processing, risk models were used based on analysis of failure modes and effects and the risk matrix of the reference practice, which were processed with the SECURE-MR-FMEA software. Results: the sensitivity analyzes on the intensity-modulated radiotherapy models showed the effects on the risk of failures associated with image processing. Conclusions: the importance of applying risk analysis in image processing to increase patient safety during external beam radiotherapy treatments was confirmed. [ABSTRACT FROM AUTHOR]

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The main contributions in the applications of nuclear sciences and technologies to the diagnosis and treatment of neoplasic diseases, obtained by medical physicists from various Havana institutions are summarized. Additionally, the main activities to guarantee the training and accreditation of medical physicists for radiodiagnosis, nuclear medicine, radiotherapy and radiation protection services in Havana hospital network is presented. [ABSTRACT FROM AUTHOR]

Intensity-modulated radiation therapy (IMRT) represents one of the most significant technical advances in radiotherapy since the advent of the medical linear accelerator, as it enables the clinical application of highly conformal and non-convex dose distributions. However, these advances do not come without risk, as IMRT represents a new paradigm in the radiation therapy process, particularly in terms of treatment quality assurance. This work focuses on one of the quality assurance aspects of IMRT, related to quality controls of multileaf collimators. A set of tests is presented to routinely evaluate the performance of this component of the accelerator to ensure the reliability and safety of the treatments. The results obtained show that most of the parameters studied comply with internationally accepted tolerances, so it is concluded that this component is suitable for use in IMRT treatments. [ABSTRACT FROM AUTHOR]

Given the lack of an internationally accepted code of practice for patient-specific quality control (PS-QA) of intensity-modulated radiation therapy (IMRT) treatments and the need to introduce this advanced modality into the clinical practice of the Radiation Therapy Service at the cedt-CIMEQ, the methodology recommended by the American Association of Physicists in Medicine Working Group 119 (AAPM TG-119) was assimilated and implemented. The procedures used for its habilitation and the results obtained are shown. It can be seen that the results obtained with the cedt-CIMEQ system for PS-QA, applied to all TG-119 test cases, fall within the confidence limits emanating from 10 reference centers. It could be concluded that, from the point of view of the reliability of the linear accelerator, the accuracy of the planning system and the precision of the PS-QA system, the cedt-CIMEQ is suitable for the introduction of IMRT in the clinic. [ABSTRACT FROM AUTHOR]

The consultation on risk studies applied to practices with ionizing radiation shows the use of prospective and reactive methods, which are associated not only with advantages, but also some disadvantages. The systematic coupling of these methods can be a resource to combine the advantages and compensate for those disadvantages. The guarantee of such development requires a methodological and computer base. The objective of this work is to present Cuban computer code SECURE-MR-FMEA, its characteristics and capacities to integrate the risk matrix methods, FMEA and its own database with reactive capabilities for incident learning. The code has been developed inside the Ministry of Public Health national research project and is currently used by several national users. Likewise, to verify the system's capabilities, the data derived from the application of the failure modes and effects analysis method, according to document TG-100, to IMRT practice were introduced. Based on this approach, the results for said practice in all available modalities of risk studies are displayed and discussed. [ABSTRACT FROM AUTHOR]

The kilovoltage radiotherapy is a recently re-implemented practice in the National Institute of Oncology and Radiology of Cuba to treat patients. One of the problems to approve its use is the assessment of risks associated to this practice. The present paper shows a summary of the pattern of accidental sequences proposed for this practice and its risk is quantified by using the risk matrix methodology. The SECURE-MR code has been used as the tool selected to implement such a practice. In addition to customary analysis facilities, this code has some other novel characteristics allowing us to establish the contributors' priorities. The global results of the risk assessment for the proposed pattern, as well as some particular optimization practices are included in this paper. [ABSTRACT FROM AUTHOR]

A modern clinical electron linear accelerator was commissioned at the Department of Radiotherapy in the Oncology and Radiobiology Institute. The use of electronic portal image device (EPID) for patientspecific intensity modulated radiotherapy (IMRT) quality assurance is assessed and validated. An IMRT step & shoot approach, using multileaf collimator was used. The EPID dose-response curve was determined for a 6 MV photon beam. The EPID effective water scattering depth (dEPID_ref) was assessed through measurements of its response versus field size variation and compared with the output factor scatter at different depths, calculated with a radiotherapy treatment planning system (TPS). Dose profiles and dose maps were calculated at dEPID_ref with the TPS, using a collapsed beam setup. The dose maps and profiles were compared with the processed EPID images for simple cases (i.e. open and wedged fields) and a more complex case (a head and neck IMRT clinical case). Comparison was performed using the Gamma function. Results showed Gamma passing rates higher than 90 % for all compared points, using comparison criteria of dose difference 3 % and 4 mm of distance to agreement. [ABSTRACT FROM AUTHOR]

The analysis of some parameters of interest in radiotherapy Medical Physics based on an experimentally validated Monte Carlo model of an Elekta Precise lineal accelerator was performed for 6 and 15 MV photon beams. The simulations were performed using the EGSnrc code. As reference for simulations, the values of the previously obtained optimal beam parameters (energy and FWHM) were used. Deposited dose calculations in water phantoms were done, on typical complex geometries commonly are used in acceptance and quality control tests, such as irregular and asymmetric fi elds. Parameters such as MLC scatter, maximum opening or closing position, and the separation between them were analyzed from calculations in water. Similarly simulations were performed on phantoms obtained from CT studies of real patients, making comparisons of the dose distribution calculated with EGSnrc and the dose distribution obtained from the computerized treatment planning systems used in routine clinical plans. All the results showed a great agreement with measurements, fi nding all of them within tolerance limits. These results allowed the possibility of using the developed model as a robust verification tool for validating calculations in very complex situations, where the accuracy of the available TPS could be questionable. [ABSTRACT FROM AUTHOR]

Simulation of a linear accelerator (linac) head requires determining the parameters that characterize the primary electron beam striking on the target which is a step that plays a vital role in the accuracy of Monte Carlo calculations. In this work, the commissioning of photon beams (6 MV and 15 MV) of an Elekta Precise accelerator, using the Monte Carlo code EGSnrc, was performed. The influence of the primary electron beam characteristics on the absorbed dose distribution for two photon qualities was studied. Using different combinations of mean energy and radial FWHM of the primary electron beam, deposited doses were calculated in a water phantom, for different fi eld sizes. Based on the deposited dose in the phantom, depth dose curves and lateral dose profiles were constructed and compared with experimental values measured in an arrangement similar to the simulation. Taking into account the main differences between calculations and measurements, an acceptability criteria based on confidence limits was implemented. As expected, the lateral dose profiles for small fi eld sizes were strongly influenced by the radial distribution (FWHM). The combinations of energy/FWHM that best reproduced the experimental results were used to generate the phase spaces, in order to obtain a model with the motorized wedge included and to calculate output factors. A good agreement was obtained between simulations and measurements for a wide range of fi eld sizes, being all the results found within the range of tolerance. [ABSTRACT FROM AUTHOR]

The evaluation of the solid state detectors response based on a Monte Carlo model of an Elekta Precise lineal accelerator, was done in this work for the beam energies of 6 y 15 MV. Simulations were performed using the EGSnrc code. Employing the optimal values of mean energy and FWHM from the primary electron beam, deposited dose in a voxelized water phantom at 100 cm of source to surface distance was calculated. Depth dose curves and lateral dose profiles were obtained. Comparison between simulations and the experimental values obtained for each detector, were done using acceptability criteria based on confidence limits. Additionally outputs factors were analyzed in each one of the study cases. Good agreement between simulations and measurements were reached. [ABSTRACT FROM AUTHOR]

The Instituto Superior de Tecnologías y Ciencias Aplicadas of the University of Havana, in collaboration with other Cuban institutions, has been developing a solid work for 40 years, in order to establish and improve undergraduate and postgraduate programs of academic formation with high quality, that include courses of radiation protection. The present work makes a comprehensive evaluation of the registered pass and present undergraduate and postgraduate programs with the objective of analyze their correspondence with the necessities of the country, the national and international recommendations in the radiation protection training, the achievements and deficiencies found in its development and the potentialities for the future. The programs of the three nuclear careers have solid and sufficient content to satisfy the minimum required by the regulatory authorities as a basic radiation protection course. The institute has also postgraduate academic figures that play a vital role in the training of experts in radiation protection. [ABSTRACT FROM AUTHOR]