8.2.2　After Radical Surgery

Radiotherapy for breast cancer after total mastectomy can achieve good results using conventional radiotherapy techniques.The Chinese Academy of Medical Sciences Cancer Hospital used two-dimensional radiotherapy technology（single field in the supraclavicular region and single electron field in the chest wall）from 2000 to 2004 to treat 328 patients.The 5-year local recurrence rate was only 5.8%［12］.When the conventional two-dimensional technique is released，the patient's treatment position is supine，the sloping plate of the shoulder and back is 15 degrees，and the upper limb of the affected side is abducted，so that the irradiation area is fully exposed and flattened.The upper boundary of the chest wall is the level of the lower edge of the clavicle.The lower boundary is equivalent to the 2cm level of the contralateral breast fold.The inner boundary is the midline of the body，and the outside is the midline or the posterior line.The irradiation field needs to cover all surgical scars，and does not require a full drainage port.The chest wall can be used with an electronic wire field，or a 6MVx line field.Regardless of the technique used，the chest wall needs to be filled with a filler for 20 to 30 Gy to increase the surface dose of the skin.If the skin.of the breast is invaded，increase the dose of the filler to 40 Gy.The thickness of the chest wall after breast cancer surgery is generally between 1.5-2cm，the energy of the electron beam is 6MeV，and the thickness of the filler is 0.5cm.Electron beam irradiation is suitable for patients with flat and thin chest wall（＜3cm）.For patients with thick chest wall，X-ray tangential field irradiation should be used.X-ray energy should be 6MV，and the thickness of filler should be 0.3～0.5cm.The upper boundary of the irradiation field in the supraclavicular region is at the level of the ring membrane，the lower boundary is at the lower edge of the clavicular head，and the inner boundary is at the midline of the body and the healthy side of the sternocleidomastoid muscle.The outside is at the inner edge of the humeral head.The supraclavicular lymphatic drainage area can be mixed with X-rays，or X-rays and electron lines.The single front field is used，and the angle of the rack is 10～15°.The prescribed dose is given 3 cm below the center of the irradiation field.At the same time，when the chest wall and the ipsilateral supraclavicular lymphatic drainage area are irradiated，when the chest wall is illuminated by electron beam，the irradiation field junction is collinear（Fig.8-06）；when the chest wall is irradiated with the tangential field，the chest wall tangential field and the clavicle upper field should be half-field.Irradiation technology is connected.On the basis of the chest wall and the supraclavicular field，when the axillary lymphatic drainage area needs to be irradiated，the conventional two-dimensional radiotherapy routinely adopts the shackle joint field，the single anterior forearm and the supraclavicular lymphatic drainage area，and the prescription dose is 3 cm below the center point.The shackle joint field and the chest wall electronic line field are collinearly connected on the skin.After the dose of the supraclavicular region reached 50 Gy，the axillary dose was calculated according to the depth of the central plane of the axilla，and the insufficient dose was supplemented by the sputum.

On the basis of the chest wall and the supraclavicular field，when the inner breast lymphatic drainage area needs to be irradiated，the inner breast is routinely irradiated with 9～12 MeV electron beam，and the first to third intercostal spaces are included.The inner boundary is the midline of the body，the outside is 5 cm on the affected side of the midline，and the upper boundary is connected with the lowerboundary of the supraclavicular field.The lower boundary is the lower edge of the 4th front rib.The outside and lower boundaries of the inner breast field are connected with the electronic line of the chest wall.(https://www.daowen.com)

Fig.8-06　Body surface markers（A）and clavicular field mapping of conventional clavicular and chest wall fields in conventional two-dimensional radiotherapy（B）