[en] Radiological Protection (RP) in a health care setting is an activity intended to protect the professionals involved in Radiodiagnostic, Nuclear Medicine or Radiotherapeutic Oncology procedures, and also the population, against the risks resulting from the use of ionizing radiation because of the impact it could have on them, In our country, application of new regulations to these practices has not involved structural changes in the facilities. Both the technological innovations and the use of new techniques in these types of procedures create a need to reassess the associated risks and to establish specific training programs for these professionals. In our country, great efforts have been made to draw up and enact regulations that assure the quality of diagnostic and therapeutic procedures using ionizing radiation, including their justification. (Author)

[en] In intensity-modulated radiation therapy (IMRT), fluence matrices obtained from a treatment planning system are usually delivered by a linear accelerator equipped with a multileaf collimator (MLC). A segmentation method is needed for decomposing these fluence matrices into segments suitable for the MLC, and the number of segments used is an important factor for treatment time. In this work, an algorithm for reduction of the number of segments (NS) is presented for unidirectional segmentations, where there is no backtracking of the MLC leaves. It uses a geometrical representation of the segmentation output for searching the key values in a fluence matrix that complicate its decomposition. The NS reduction is achieved by performing minor modifications in these values, under the conditions of avoiding substantial modifications of the dose-volume histogram, and does not increase in average the total number of monitor units delivered. The proposed method was tested using two clinical cases planned with the PCRT 3D (registered) treatment planning system. (note)