Effect of Target Volume on Treatment Planning Parameters of Skull Base Lesions and Functional Disorders in Cyber Knife

Abstract

Background: Benign and malignant tumoral growth can be controlled by several ways of which one is by irradiating the target by ionizing radiation (X-rays or gamma rays). Initially it was done by conventional radiation therapy offering fewer field orientations, thus increasing the dose to surrounding normal tissue and inability to achieve the required dose to the target, which was overcome by applying converging beams from different angles focused at a single spot (target), thus achieving higher doses with adequate normal tissue sparing. Method: A retrospective review of 270 patients treated with Cyber knife in Cyber knife stereotactic Radiosurgery department JPMC Karachi was carried out and 88 patients with skull base lesions of anterior middle and posterior cranial fossa were included. The study data included treatment planning parameters and diagnosis of the patients. Results: Data was statistically analyzed on SPSS V.22 software. Treatment planning parameters were compared with volume of the lesions as defined in the treatment planning data. On statistical analysis significant 2-tailed value at 95% confidence interval p<0.001 was obtained on correlating target volume with the homogeneity and new conformity indices. Conclusion: In this study we have appreciated that tumors with greater volumes and treated with larger and multiple collimators were subjected to increased homogeneity and new conformity indices as comparable to those lesions with lesser volumes and were treated with smaller collimator sizes. Thus we have noted a significant impact of tumor volume on homogeneity and new conformity indices.