Geometrical errors are presented as deviation between intended geometry of radiotherapy plan and real geometry of radiotherapy treatment. Total geometrical error is build up of smaller errors, which can be generally classified as set-up, organ motion, organ delineation, and technical condition related errors. The clear distinction must be made between systematic and random component of these errors and its amount should be encountered in treatment planning process. Errors’ measuring for specific patient group with electronic portal imaging device and proper correction strategy enables to predict, minimize, and keep under control the amount for most of geometrical errors; it also improves the preciseness of treatment and consequent results. Nature and characteristics of most frequent geometrical errors are discussed and clinically applicable methods for their proper managing are described in this paper

BackgroundThe aim of the study was to examine on the CT basis the inter-application displacement of the positions D0.1cc, D1cc and D2cc of the brachytherapy dose applied to the bladder and rectum of the patients with inoperable cervical cancer.Patients and methodsThis prospective study included 30 patients with cervical cancer who were treated by concomitant chemo-radiotherapy. HDR intracavitary brachytherapy was made by the applicators type Fletcher tandem and ovoids. For each brachytherapy application the position D0.1cc was determined of the bladder and rectum that receive a brachytherapty dose. Then, based on the X, Y, and Z axis displacement, inter-application mean X, Y, and Z axis displacements were calculated as well as their displacement vectors (R). It has been analyzed whether there is statistically significant difference in inter-application displacement of the position of the brachytherapy dose D0.1cc, D1cc and D2cc of the bladder and rectum. The ANOVA test and post-hoc analysis by Tukey method were used for testing statistical importance of differences among the groups analyzed. The difference among the groups analyzed was considered significant if p < 0.05.ResultsThere are significant inter-application displacements of the position of the brachytherapy dose D0,1cc, D1cc and D2cc of the bladder and rectum.ConclusionsWhen we calculate the cumulative brachytherapy dose by summing up D0,1cc, D1cc and D2cc of the organs at risk for all the applications, we must bear in mind their inter-application displacement, and the fact that it is less likely that the worst scenario would indeed happen.

The referent volume received HDR-ICBT prescribed dose. The maximum ICBT percentage dose to the rectum and urinary bladder was 101% and 106% respectively. In all 3D-CRT plans almost 100% of planning target volume (PTV) was covered by 95% therapy isodose surface. From 12 - 13% of the rectum and 1-3% urinary bladder volume were covered by 100% isodose surface, with the highest maximum dose of 104% and 101%, respectively. Comparison of the PTV dose coverage and the maximum dose to the rectum and urinary bladder for HDR-ICBT and 3D-CRT plans showed no major difference. CONCLUSION; 3D-CRT could be considered as adequate replacement for ICBT in the adjuvant postoperative treatment of the vaginal cuff and upper thi-rd of present vaginal tissue. Time-dose-fractionation pattern for HDR-ICBT may be safely applied for 3D-CRT.

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Breast radiotherapy (RT) has changed over the passed few decades mainly due to changes in locoregional treatment of the breast cancer and improvements in technology of radiotherapy equipment. It has now become the standard part of the breast conserving procedure, as well as in patients who underwent mastectomy with T3 and/or 4 or more positive nodes in axilla. In treatment of ductal carcinoma in situ, postoperative RT after lumpectomy is almost always required, because it reduces ipsilateral invasive and DCIS recurrence by approximately 50-60%. For invasive breast cancer RT decreases the locoregional relapse rate by 70%. The indication for postoperative RT and the definition of the target volumes depend on the prognostic factors and surgical procedures. The overview by the Early Breast cancer Trialists&rsquo; Collaborative Group (EBCTCG) demonstrates for the first time, that postoperative RT is not only important in achieving loco-regional control, but also has significant influence on long-term survival. This benefit of postoperative RT is achieved by proper indication of RT and more importantly by using modern RT techniques that can avoid the serious late side-effects