Analysis Of The Real-time Dose Change Rule Of The Intensity Modulated Radiotherapy

The basic characteristics of Intensity modulated radiation therapy(IMRT) is to adjust the rate of the output dose in the field, so as to keep the dose distribution shape of high dosage zone in three dimensions the same as the shape of lesion area; that is to realize three dimensional conform. To ensure accurate radiation therapy, the basic fundamental is the accurate delivery of radiation dose.Many uncertain factors exist during the executing process of radiation therapy plan, so there are errors for a variety of reasons in reality. Though medical units would adopt all kinds of quality control methods to avoid error before the implementation of radiation therapy, dose mistakes still often occur in the worldwide. So the real-time monitoring of radiation dose is becoming the necessary radiation therapy method for quality control and quality assurance, which would confirm and guarantee the accuracy and safety of the implementation of radiation therapy in the terminal.This paper is studying for the real time dose monitoring throughout the whole therapy process of cancer patients who are receiving radiation therapy by using multichannel semiconductor dosimeter and dynamic multi-leaf collimator intensity technology(Sliding Window). The patients has been divided into three groups which is head, chest and abdomen; to better measure the radiation input and output dose, the gantry angle of 0°, 180°, 90°, 270° in the field at therapy plan were selected for real-time dose monitoring at the field central axis direction. Then, the monitoring results have been comparative analysis and the reason and regular rule of the change of real-time monitoring dose were discussed.The result shows that, as for the change difference of real time monitoring dose in the whole therapy, the head group patients have the least change difference of radiation dose, then are the chest group patients while the abdomen group patients have the largest change difference; it has also been observed that the change of real time monitoring dose is related with patient age, receiving CBCT correction replacement or not before therapy and the length of a single treatment, etc.; this paper has discussed above questions.