External irradiation and brachytherapy treatment of cancer

By | April 3, 2012

External irradiation and brachytherapy treatment of cancer, due to radioactive sources and the use of micro-computer control and optimization of dose distribution system behind the technology, esophageal brachytherapy is increasingly common. The biggest advantage of brachytherapy is to increase the dose with the sharp decline in the depth of exposure, can improve local tumor radiation dose, while the surrounding normal tissues is very low. But this is the fatal shortcoming of brachytherapy, due to a sharp fall in homogeneous dose distribution is very uneven, the depth of the effective exposure is very limited.
External irradiation and brachytherapy treatment of cancer, esophageal cancer, brachytherapy primarily as a palliative treatment of esophageal malignant obstruction means; as well as supplementary irradiation of esophageal cancer with earlier radical radiotherapy to improve tumor dose profile Board to reduce the peripheral The subject content; and treatment with external beam radiotherapy combined with recurrent esophageal cancer. Unless the tumor is very superficial, brachytherapy is not as simple radical means. Endovascular treatment before CT or intraluminal esophageal ultrasonography B, when the tumor invasion depth of more than 1.Ocm brachytherapy difficult to achieve when the radical purpose. Breaking external irradiation combined with intracavitary treatment of esophageal cancer according to the time to be the first cavity after external beam radiation, external radiation dose less than 50Gy, each dose of intracavitary irradiation 5-7Gy, total dose of less than 20Gy appropriate. Surface dose is high, high incidence of mucosal burn, ulcer and perforation, the latter prone to esophageal stenosis, it should avoid the abuse of brachytherapy.
Advanced esophageal cancer brachytherapy has a good palliative effect, obstruction of 60% _80% improvement, remission can usually 3_6 months of 1988, SurRK reported high-dose fractionated radiotherapy for 172 cases of cavity with advanced esophageal cancer, 22 cases died of disease progression during treatment, the whole group 1 year survival rate of 19.4%, median survival was 6.2 months; 43 cases of radiation esophageal stricture, 15 cases had thin tube. Author believes that each 8Gy, total dose of 16Gy or per 6Gy, total dose of 18Gy, at intervals of 1 week is better than 12Gy/2t.
Brachytherapy radioactive sources are drilling 60, 137 full, according to 192, according to the output dose rate, brachytherapy can be divided into low dose rate (LDR, 0.4Gylh2Gy / h), the dose rate (MDR2Gy/h_12Gylh) and high dose rate (HDR> 12Gy / h).
1997 American Society of Clinical Brachytherapy Research Committee has developed Guidelines for the application brachytherapy of esophageal cancer, esophageal cancer brachytherapy to the guide is divided into radical and palliative two categories.
Radical treatment: external beam brachytherapy as a supplement external beam 60Gy 2_3 weeks after the interval again brachytherapy. High dose rate per 5Gy, 2 times total lOGy; a single low dose rate given 20Gy, such as the addition of chemotherapy, external radiation dose is reduced to 45_50Gy. Esophageal thin, cervical esophageal esophageal obstruction is complete contraindication.
Palliative treatment: external beam radiotherapy or who have received the expected short survival time can be a simple case of brachytherapy. High dose rate irradiation 10_l4Gyl times to 2 times, or low dose rate irradiation 20_40Gy, 1_2 times; those who had not received external irradiation, external irradiation 30_40Gy, the high dose rate irradiation 10_14Gy, 1 times to 2 times or a single low dose rate irradiation 20_25Gy ; not received external radiation and can be expected to survive longer than 6 months, according to radical program. The guide is particularly pointed out:
Length means the effective treatment of esophageal tumor length mirror plus the naked eye can see both ends of the 1_2cm.
External irradiation and brachytherapy treatment of cancer, prescription dose: from the source center with 1cm. Shi source device to 0.6-1.0cm in diameter is appropriate. First external beam radiotherapy, the tumor may not fully back or reduction for brachytherapy.

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