Spinal cord dose reduction using an anterior 13 MeV electron field situated between a split anterior 60Co...

As part of the treatment for lymphoma, disease involving the supraclavicular region has been treated with megavoltage 60Co photons to a midline dose of 30 to 45 Gy through an anterior involved field and a supplementary posterior field when necessary. The spinal cord was shielded with a 5 cm lead block during treatment to the posterior field. A typical 40 Gy treatment results in a dose to the lower cervical and upper thoracic spinal cord in the range of 22 to 26 Gy, a level that could compromise subsequent mediastinal treatment in the event of a relapse. To reduce this cord dose, the midportion of the anterior supraclavicular 60Co To reduce this cord dose, the midportion of the anterior supraclavicular 60Co field was replaced with a high-energy (13 MeV) electron port, which reduces the dose to the cord to below 6 Gy in the average adult patient. This modification of the routine supraclavicular treatment allows greater flexibility in future treatment in the event of a mediastinal relapse.