Purpose: For craniospinal axis irradiation in young children sometimes anesthesia is required. In order to minimize risks from the anesthesist's point of view supine position would be preferable to standard prone position. In case of irradiation in supine position verification of the 3-field junction in the cervical region causes problems, because there is no direct visual control. For such situations the clinical application of a new technique is presented.
Patients and methods: For treatment planning a modern 3D planning system was necessary. Patient's positioning was done by using a vacuum-form body immobilizer and an integrated head mask. Radiation fields were placed only by table movements being calculated by the planning system in relation to a reference point at the patient's surface. In addition to common verification films specially prepared small films were used for the 3-field junction in the cervical region. These films were placed close to the patient for the whole time of each radiation session being exposed by every radiation field.
Results: Two children (age 3 and 5 years, respectively) were irradiated as described. Twenty-eight of those specially prepared films were exposed. Two films (7%) had to be excluded because of inadequate exposure. An overlap of radiation fields was seen on 1 of the 26 remaining films (4%), whereas an unacceptable gap was not found. Acute skin reactions were comparable to those observed in patients being irradiated in standard prone position.
Conclusion: The presented technique for craniospinal axis irradiation in supine position including field verification was not only precise and reproducable, but also comfortable and safe for the patient. We suggest it as a new option for craniospinal axis irradiation in children.