Radiotherapy irradiation method

By | March 21, 2012

Radiotherapy irradiation method 1. Exposure range settings
The establishment of the scope and target irradiation: target is the actual violations of the scope of the tumor, including the primary lesion and regional lymph nodes, radiation include more up and down outside the region also include lesions that may exist around the section and sub-clinical and regional lymph node drainage area. Esophageal cancer has a strong ability of local invasion and spread, not only near the structure can be widely violated, and the upper and lower section of the invasion and spread. 85% of diagnosed cases of esophageal lesions when more than 5cm, and its length far exceeds the actual violation of X-ray food inspection findings dam length. Any period of esophageal cancer are likely to shift to the supraclavicular region, mediastinum, and upper abdominal lymph nodes. Radiotherapy for esophageal cancer is currently most advocated reducing exposure to the appropriate scope and use of reduced field irradiation technique. However, cancer treatment center with some foreign exposure range than large domestic. Esophageal exposure to a lesser extent China, is generally based on esophageal X-ray film and CT findings, extension of the tumor and the actual size of the illuminated area is determined, including the upper and lower ends of the target and the lesion extended 3 – 4cm, normal esophagus and lesions on both sides of at least expansion of 2cm, including lymph node drainage area adjacent to esophageal lesions. Then through a treatment station for treatment treatment plan optimization planning system to determine the radiation field size, field number, the field angle, whether or compensation plus filler filter, the field dose ratio. Optimized treatment plan should meet the following conditions, namely, should cover the entire tumor invasion in the 90% isodose region, sub-clinical lesions should be included in the 70% – 80% isodose region, the spinal cord should be at 70% isodose area , the trachea by the amount of <70Gy.
Esophageal cancer radiotherapy irradiation method 2. radiation field settings
Cervical esophageal lesions in the cervical length <3cm, wild side can be set on both sides of the vertical or horizontal radiation exposure, field width 5 – 6cm. Lesions were located more than double before the lower neck oblique field plus 30. Die-shaped filter into a corner exposure, field width 5 – 6cm. The advantage is a more reasonable distribution of isodose curves, by the decline in the trachea, esophagus, and paraspinal tissues surrounding exposure more fully, also decreased the amount of spinal cord, radiation field to reach 5-6cm wide and rarely occurs when radiation field overlap. Upper thoracic esophageal cancer as the general double oblique angle of 60 wild. The incident irradiation and 30. Or 45. Die-shaped plate technology. Cross-field radiation by three, the former set up a "T" word field (including the double clavicle), the latter two oblique field dose ratio of 2:3 to reduce the amount subject to the spinal cord to ensure that less than 70% of the spinal cord. Esophageal chest vertical field with the former, the latter two angled cross-field irradiation. Both before and after the vertical field can be radiation dose of 40Gy / 4 weeks into the corner to the back of the two cross-exposure to wild enough. Thoracic esophageal cancer with chest radiation field settings the same as esophageal cancer, but across the lower part of the radiation field should be widened, usually 8-10cm, the vertical radiation field after two previous dose of 40Gy / 4 weeks, replaced by a square field, Two wild and other centers from behind to adequate exposure.
In addition, radiotherapy irradiation method applied when conditions permit treatment planning system to choose the best exposure to the program, and then use simulator calibration, and to ensure that the amount of spinal cord tolerance dose in the following (part of the spinal cord irradiation should be in the 45Gy / 5 weeks points 25 times less).

Leave a Reply

Your email address will not be published. Required fields are marked *