Dose Distribution Comparison of Cerebrospinal Axis Irradiation. Helical Tomotherapy vs Proton Pencil Beam Scanning.

Central nervous system tumors are diagnosed in 1--2% of all adult patients. Most cases are regarding brain tumors in which a standard of care is a combined treatment, i.e., surgical resection, radiotherapy, and chemotherapy. Radiation therapy in the cerebrospinal axis is becoming more common in oncological practice. The aim of this study is to compare dose distributions in treatment plans for the cerebrospinal axis adult patients irradiation using photon and proton beams. Six treatment cases were investigated. Dose distributions in the target and critical organs were analyzed in terms of uniformity, maximum, average, and minimum dose for target and integral dose. The high dose gradient areas that represent the resilience of treatment plans to uncertainties related to patient positioning and organ mobility were also investigated. The technique of proton radiotherapy requires joining the fields. The dose distributions obtained in proton plans are much more favorable in terms of the protection of critical organs and integral dose reduction. On the other hand, the treatment plans prepared for the photon helical technique are characterized by a greater dose distribution homogeneity in the areas where fields need to be joined in proton techniques. Those photon plans were proved to be less sensitive to errors resulting from the geometry of the patient's position. Irradiation times obtained for both techniques are not comparable. Each technique has its own benefits and, depending on availability, might be applied in the treatment of adult central nervous system tumors. [ABSTRACT FROM AUTHOR]