2015年 · 第35卷第09期

With the increasingly widespread application of CT examination in clinical practice, the radiation dose and biological damage effects have become the focus of attention, and the risk of cancer induced by CT radiation has become the focus of research by radiologists^[1]。 It has been reported that 1.5% to 2.0% of cancer patients in the United States may be attributed to radiation damage caused by CT examination^[2]。 DNA double-strand breaks (DSBs) are recognized as the most important biological damage mechanism for ionizing radiation-induced cancer and hereditary diseases^[3]One of the earliest stages of cell response to double-helix structural destruction is the formation of the phosphorylated form of H2AX histone heterotype, γ-H2AX^[4,5]。 In this study, the number of γ-H2AX focal points in human peripheral blood lymphocytes before and after CT scan and the correlation with CT dose were compared and analyzed by γ-H2AX immunofluorescence analysis technique, combined with in vivo and in vitro clinical experiments, aiming to quantitatively evaluate the biological dose-response relationship of CT radiation.

Radical surgery and radiotherapy are the most common treatments for cervical cancer, Ⅰ_astage surgical resection, Ⅰ_b～Ⅱ_aAt present, there is no unified treatment standard in the middle and late stages, and concurrent chemoradiotherapy is the main treatment. For intermediate and advanced patients, radiotherapy is the most important treatment method. With the continuous development of precise radiotherapy technology, external irradiation of cervical cancer is a commonly used intensity modulated radiotherapy technology, which can better protect normal organs. In this study, a three-dimensional treatment planning system was used to formulate radiotherapy plans in two positions (supine position and prone position), and then the differences in the exposure doses of small intestine, bladder and rectum in the two positions were compared according to the dose-volume histogram (DVH).

Medical electron accelerator has become the main equipment of radiotherapy because of its high radiation energy, strong penetration ability and small penumbra area. When performing radiation therapy, medical electron accelerators inevitably emit X-rays and neutrons from the handpiece shield, i.e. leakage radiation, which is irrelevant to the treatment but detrimental to the patient. Therefore, GBZ 126-2011 "Requirements for Radiation Protection of Electron Accelerator Radiotherapy" specifies the requirements for leakage radiation outside the M region, which means in a circular plane perpendicular to the useful harness axis and with an epitaxial diameter of 2 m (excluding the patient plane, the area centered on the useful harness axis and bounded by the maximum irradiation field, i.e. M region)^[1]。 In this study, the results of leakage radiation measurement outside the M zone of 17 medical electron accelerators were reported, so as to evaluate the protective performance of medical electron accelerators and conduct relevant analysis.

Individual dose monitoring data is not only an important parameter for evaluating radiation protection effectiveness, but also a basis for evaluating whether radiation workers are exposed to radiation hazards^[1]。 The results of personal dose monitoring of external exposure of some radiation workers in Jiangsu Province from 2009 to 2013 are reported as follows.