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后装机对肿瘤的治疗是利用~(192)铱在肿瘤某一点或几点驻留时间的长短来满足肿瘤的治疗剂量。这样,在整个治疗区内就形成了一个相对不均匀的剂量分布,离放射源驻留点近的地方射线剂量就高,远离驻留点或两驻留点之间的范围内肿瘤受线量相对就低。另外,放射性~(192)铱源很小,强度有限,很难在较大范围内形成均匀的剂量强度,在近距离测量时,电离室和放射源的距离差1cm,剂量错4倍,可
Post-installation treatment of tumors is to use the (192) sputum at a certain point in the tumor or the length of time to satisfy the therapeutic dose of the tumor. In this way, a relatively uneven dose distribution is formed throughout the treatment area, where the dose of radiation is high near the point where the radiation source resides, and the amount of radiation received by the tumor in the range between the distance from the residing point or the two residing points. Relatively low. In addition, radioactive ~ (192) germanium source is very small, the intensity is limited, it is difficult to form a uniform dose intensity in a wide range, in the close-range measurement, the distance between the ionization chamber and the radioactive source is 1cm, the dose is wrong 4 times, can