Determination of geometric accuracy of radiotherapy fields by port film and DRR using Matlab Graphical User Interface Introduction: Radiation therapy is one of the methods of cancer treatment. In this method, it is necessary to avoid harming the healthy tissues of the patient which is in the vicinity of the target, as much as possible. Treatment verification is one of the most important steps of radiation therapy which has two usual methods, using Port film and EPID. The accuracy and precision of treatment in EPIDless centers are usually of concern. By entering EPID into the treatment verification process, no more studies have been done for increasing the precision of treatment verification by using port film. The purpose of this study is to determine and verify the exact location of radiation therapy fields by using portfilm and DRR as low  and :122,Materials: Initially, by writing appropriate algorithm for port film in the megavoltage irradiation, detectable contrast was created for the image and then by using appropriate markers and developing program by MATLAB as DRR Port Registration, Semiautomatic and automatic registration between port film and DRR images were performed for Pelvic and Chest phantoms and the results were compared withEPID consequences in similar  By using this :185,software, DRR and port film as treatment verification tools, the precision of treatment verification and accuracy of radiation therapy fields were achieved in the extent of the millimeter. The study of validation results with EPID demonstrated that the mean absolute average error in angle is equal to 0.5926 degrees, 1.703 mm in the X direction and 2.42716 mm in the Y direction. Also, the mean absolute average errors in MATLAB validation is equal to 0.2 degrees, 0.75 mm in the X direction and 0.81 in the  and :275,0.228% in  The results of this study :279,illustrated that using this software and suitable lowcost hardware in the centers with lack of EPID can increase the precision of treatment verification to the millimeter and it can be introduced as a suitable alternative for EPID in centers for increasing treatment accuracy.

Assessment of Position Repeatability Error in an Electromagnetic Tracking System for Surgical Navigation In this paper we present a study of the repeatability of an innovative electromagnetic tracking system (EMTS) for surgical navigation, developed to overcome the state of the art of current commercial systems, allowing for the placement of the magnetic field generator far from the operating table. Previous studies led to the development of a preliminary EMTS prototype. Several hardware improvements are described, which result in noise reduction in both signal generation and the measurement process, as shown by experimental tests. The analysis of experimental results has highlighted the presence of drift in voltage components, whose effect has been quantified and related to the variation of the sensor position. Repeatability in the sensor position measurement is evaluated by means of the propagation of the voltage repeatability error, and the results are compared with the performance of the Aurora system (which represents the state of the art for EMTS for surgical navigation), showing a repeatability error about ten times lower. Finally, the proposed improvements aim to overcome the limited operating distance between the field generator and electromagnetic (EM) sensors provided by commercial EM tracking systems for surgical applications and seem to provide a not negligible technological advantage.