Room: ePoster Forums
Purpose: To compare the TMR10 and convolution dose calculation algorithms in order to assess whether the algorithms produce clinically significant dose differences in Gamma Knife stereotactic radiosurgery (SRS) treatments.
Methods: Treatment plans were analyzed from ten patients who have undergone Gamma Knife SRS treatments with a prescribed dose of 13-22 Gy, normalized to the 50% isodose line. Patient plans were calculated using Leksell GammaPlan Version 10 treatment planning system utilizing the TMR10 and convolution dose calculation algorithms in order to create a paired data set for comparison. Plan evaluation was based on the DVH parameters of minimum, mean, maximum and integral doses. Statistical analysis was done using Studentâ€™s two-tailed t-test.
Results: The ratio (R), defined as conformal/TMR10, of average integral doses calculated by the convolution dose calculation algorithm to that by the TMR10 algorithm were 0.997Â±0.013 for target (p=0.28), 1.048Â±0.189 (p=0.48) for skull, 1.005Â±0.049 (p=0.68) for brainstem, 0.997Â±0.041 (p=0.84) for optic chiasm, 0.95Â±0.068 (p=0.08) for left cochlea, 0.951Â±0.118 (p=0.26) for right cochlea, 0.993Â±0.082 (p=0.61) for left optic nerve, and 0.997Â±0.061 (p=0.88) for right optic nerve. The ratio R for minimum, mean, and maximum doses were (0.995Â±0.025, p=0.55; 1.001Â±0.015, p=0.91; 1.002Â±0.004, p=0.17) for target, (0.834Â±0.200, p=0.34; 0.782Â±0.214, p=0.33; 1.001Â±0.028, p=0.90) for skull, (1.033Â±0.266, p=0.32; 1.007Â±0.059, p=0.56; 1.004Â±0.027, p=0.60) for brainstem, (0.954Â±0.070, p=0.17; 0.997Â±0.040, p=0.80; 1.001Â±0.036, p=0.90) for optic chiasm, (0.932Â±0.081, p=0.05; 0.960Â±0.68, p=0.07; 0.975Â±0.7, p=0.09) for left cochlea, (0.922Â±0.111, p=0.04; 0.957Â±0.118, p=0.10; 0.952Â±0.126, p=0.15) for right cochlea, (0.970Â±0.095, p=0.15; 0.986Â±0.085, p=0.32; 0.998Â±0.064, p=0.90) for left optic nerve, and (0.985Â±0.067, p=0.52; 1.003Â±0.065, p=0.81; 1.003Â±0.053, p=0.72) for right optic nerve, respectively.
Conclusion: Both techniques achieved similar results. Overall, the differences were not statistically significant in most of the parameters that we compared. A decision was thus made to continue utilizing the TMR10 algorithm for dose calculation at our institution.
Not Applicable / None Entered.