2016年 · 第36卷第12期

At present, precise radiotherapy for tumors has become the mainstream of radiotherapy nowadays. The advantages of precise radiotherapy to kill tumor cells to the maximum extent and protect normal tissues to the maximum extent have become an important direction of radiotherapy development. However, due to the inherent respiratory movement of many organs of human body such as lung, liver, breast, etc., the position of radiotherapy target area deviates from the static irradiation field of accelerator. In order to ensure that the tumor target area is always in the high dose area during radiotherapy, the traditional practice is to meet the high dose requirement of the target area by expanding the boundary of the existing target area (clinical target area), but at the same time, it will lead to an increase in the exposure dose of more normal tissues or organs around the target area. In order to make radiotherapy more accurate, this study explored and attempted the combination of intensity modulated radiotherapy and apnea technique under the existing conditions in our hospital to further reduce the exposure dose of normal lung tissue.

In recent years, two radiotherapy devices that use carbon ion beam to treat cancer have appeared in China, namely, the scattered carbon particle beam therapy equipment developed by Lanzhou Institute of Modern Physics and the active spot scanning carbon ion therapy equipment of Shanghai Proton and Heavy Ion Hospital. These two devices represent two different types of carbon ion beams: scattering beams and spot scanning beams. The carbon ion scattering beam mainly refers to the carbon ion beam after being extended by the scatterer and the range modulator; Active point-scanning beam, also known as pen-shaped beam, uses deflection magnets to control the scanning position of the beam, and the energy change adjusts the depth distribution of carbon ion beam to form a pen-shaped carbon ion beam^[1,2]。 Carbon ion therapy devices need a lot of quality control tests before being put into clinical treatment. Among them, carbon ion depth dose distribution is an important content of quality control testing of carbon ion therapy devices. By measuring the depth dose distribution of carbon ion beam flow, important information such as the position of the maximum dose point (Bragg peak) and the maximum penetration depth of the therapeutic device can be known.