Total skin electron irradiation
Total Skin Electron Irradiation (TSEI) is a special radiotherapeutic technique that aims to irradiate the patient’s whole skin while sparing all other organs from any appreciable radiation dose. Since the skin is a superficial organ, the choice of electron beams for treatment of generalized skin malignancies (most often mycosis fungoides) is obvious. The patient population requiring TSEI is relatively small and the TSEI techniques are relatively complex and cumbersome, therefore the TSEI technique is available only in specialised radiotherapy centres. All contemporary TSEI procedures are based on linacs which are used for conventional radiotherapy and modified for delivery of the large and uniform electron fields required for the TSEI.
Patients are generally treated with multiple large electron beams by rotating them in a large electron field. Various techniques involving beam spoilers or special filters are used to produce the large, clinical electron beam at an extended SSD. Bremsstrahlung contamination of the electron beam, a potential detriment to the patient, must be known for each TSEI technique to ensure that the total prescribed electron dose is not accompanied by an unacceptably high total body photon dose. Certain areas of the patient’s skin as well as some organs (such as nails and eyes) may have to be shielded in order to avoid treatment morbidity.
Introduction to References
The various aspects of the early types of TSEI, including requirements for a QA programme, were summarised in the initial AAPM report. More recent developments in the field of SRT can be found in J. Van Dyk's Compendium, the IAEA Handbook, and the Handbook of Radiotherapy Physics.