Search

Copyright of Bistua: Revista de la Facultad de Ciencias Básicas is the property of Facultad de Ciencias Basicas de la Universidad de Pamplona and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bistua: Revista de la Facultad de Ciencias Básicas is the property of Facultad de Ciencias Basicas de la Universidad de Pamplona and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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]

A patient-specific quality assurance (QA) program to carry out the dosimetric verification of the intensity modulated radiation therapy (IMRT) was optimized at the Department of Radiotherapy at the Institute of Oncology and Radiobiology, belonging to the Ministry of Public Health of Cuba. A dosimetric set-up composed of two-dimensional (2D) ionization chambers and an octagonal phantom were used to implement a patient-specific IMRT QA in a more comprehensive manner (collapsed and non-collapsed fields), keeping the accuracy and precision standards of these controls according to institutional protocols and international guidelines. The proposed procedure was used in three clinical IMRT cases for head and neck cancers. The confidence limit calculated from the passing rates for evaluated points in the compound dose maps was 90 % for the Gamma function comparison. The tolerance criteria used was a distance to agreement of 3 mm and the dose difference of 4 %. These results are within the institutional accepted limits and the recommended values as set by international guidelines for these kinds of tests. [ABSTRACT FROM AUTHOR]