A simple technique for cranio-spinal irradiation in young pediatric patients

Abstract

12501 Background: Craniospinal irradiation (CSI) is a complex radiotherapy technique. The implementation of craniospinal radiation makes atleast one junction between orthogonal cranial and spinal radiation fields. The traditional problem with CSI has been the concern over the dose delivered to the junctional area. We are presenting a simple technique of CSI which is easy to plan, treat and delivers a uniform dose to the entire cord. Methods: Ten patients of medulloblastoma suitable for CSI were taken in this study. All patients underwent CT based treatment planning. The patients were immobilized in prone position using the combination of uniframe and vacloc. CT scanning was performed for all the patients with 5 mm slice thickness. The cranium was treated with a dose of 36 Gy in 20# over 4 weeks and the spine with a dose of 30Gy in 20# over 4 weeks. Subsequently, the cranium was boosted to a dose of 20 Gy in 10 fractions over 2 weeks. For the cranial region, parallel opposed fields were used with half beam block provided by asymmetric jaws with the central axis in the caudal edge of the field. Subsequently, the gantry was brought to head top position and the couch was brought vertically down. The field length was opened to desired position to treat the spine by asymmetric jaws. In treatment planning system, doses were prescribed to the reference point placed in the cranial and spinal field. The maximum, minimum and mean dose to each anatomical structure was computed from dose volume histogram by summing the cranial and the spinal treatment plans. The junctional dose was calculated with special emphasis on field junction. Results: The results showed that the junction between the cranial and the spinal fields received relatively uniform dose. The hot spots in the cranial field were reduced by applying field in field technique. The daily setup time required for the treatment was considerably reduced with this technique. Patient with spinal field less than 30 cm from C2-C3 junction to the S1-S2 junction are ideally suited for this technique. Conclusions: Our technique of craniospinal irradiation is simple and technically sound. This technique can be applied for young pediatric patients undergoing CSI. The technique effectively deals with craniospinal irradiation No significant financial relationships to disclose.