DVH Analysis of Cobalt-60 treatment plans incorporating a recently developed MLC

Abstract

Purpose:The aim of this investigation was to measure the gain in DVH indices when the recently developed MLC was used for Cobalt-60 treatments. Methods: A prototype multileaf collimator (MLC) that was retrofitted to telecobalt-60 therapy machine was reported and is currently proposed for clinical trials in our institution. Ten patients' plans that were previously planned through an ECLIPSE ® treatment planning system and were treated with open beams from Cobalt-60 machine were imported into Radiation Oncology Planning System [ROPS] and the dose calculations and dose volume histogram (DVH) analysis were performed. The plans were re-planned using the Cobalt-MLC, a feature available in the ROPS planning system. The DVH analysis consisted of conformity index (CI), homogeneity index (HI) and conformation number (CN). The results of this study are presented in this paper. The analysis specifically aimed at measuring the gain in these indices when the MLC was compared with open beams. Results: DVH Comparison of ten sites using open and Cobalt MLC fields showed that the use of MLC results in reduced normal tissue dose, while maintaining the GTV dose. Lower value of CI for normal structures was observed demonstrating the sparing of critical organs when MLC was used. The index HI was studied to show the significance of hot spots outside the PTV. Hot spots were observed even with MLC beams for some cases due to less number of fields. Conclusion: It has been demonstrated through DVH analysis that the use of the recently developed MLC for Cobalt Teletherapy machine results in benefit for the treatment of patients.

Validation of Leaf Design Characteristics of an Add-on Automated Multi Leaf Collimator for Telecobalt Therapy Machine

“…The detailed specifications of ROPS can be found from the website at https://sites.google.com/ site/tjcsrops. Publications on ROPS treatment planning system show feasibility in generating conformal plans for clinical radiation beams for different treatment machines [13,14]. Three dimensional (3D) conformal planning requires an accurate delineation of the target volume and beam shaping to conform to the volume.…”

Simulación Monte Carlo de un haz de radiación de una fuente de cobalto 60 en condiciones de referencia

“…Por décadas los equipos de teleterapia que utilizan fuentes de cobalto 60 han contribuido a la lucha contra el cáncer [5], hay países que aun utilizan estos equipos, incorporándoles mejoras tecnológicas como un colimador multiláminas [6], [7], que les permitan brindar otros tipos de tratamiento como Radioterapia de Intensidad Modulada (IMRT) [8]. En la actualidad, Costa Rica ya no cuenta con este tipo de equipos, pero se cuenta con los datos dosimétricos de unidades que fueron utilizadas en clínica por muchos años.…”