Use of the Laser Beam for Markerless Tracking of the Patient Breathing Motion for Respiratory Gated Radiotherapy

Respiratory gating is broadly used method in modern radiotherapy to lessen uncertainties related to patient respiratory motion. Most of the currently available commercial respiratory gating systems involve use of mechanical markers attached to the patient chest for caption of motion during CT scanning as well as radiotherapy treatment. The present paper explores the possibility to use infrared laser light reflected from the moving surface as optical markers instead of mechanical marker box for commercially available gating systems. Performed tests demonstrated, that reflected laser spot movement can be used to obtain breathing patterns, and acquired signals are suitable for respiratory gating

The Impact of the Detector Size Effects in Region of High Dose Gradients on Point Dose Measurement

Reģistrētā doza ir atkarīga no detektora izmēra

Modeling of the Response of Ionization Chambers in Radiotherapy Fields with Dynamic Intensity Modulation

Ionization chamber (IC) is the most common and trusted radiation detector in Radiotherapy (RT) dosimetry. However, due to its finite size detector volume have an impact on point dose easurements especially in a penumbra and regions of high dose gradients inside Intensity odulated Radiotherapy (IMRT) fields. The aim of this work is to make a comparison of measured and modeled point doses in the case of dynamic radiotherapy using IC`s of different active volumes, to evaluate magnitude of the chamber volume effect on the discrepancy between the calculated and the measured dose