open access
Monte Carlo study on the impact of spinal fixation rods on dose distribution in photon beams
open access
Abstract
Background
Metal spinal rods are used as fixation devices in spinal surgery. The attenuation effect of these rods has not been completely studied for patients with spinal rods and requiring spinal radiotherapy.
Aim
The purpose of the current study was to investigate the dosimetric perturbation effect of metallic spinal rods in different photon beams.
Materials/Methods
Three photon beams of 6, 9 and 15MV were modelled using MCNP4C Monte Carlo (MC) code. The geometry consisted of two spinal rods at a depth of 4cm and a water phantom was used for MC calculations. The beam profiles at depths of 5.5, 6.5 and 7.5cm were calculated.
Results
Dose reductions of 10.2–11.2% and 5–6.2% were observed for steel and titanium rods respectively. The insertion of metallic rods into the photon beams did not change the spinal cord received dose but the effect of both types of rods on the target region behind the rods cannot be ignored, especially for steel rods.
Conclusions
Our results suggest that for reliable spinal radiotherapy the dose attenuation effect of spinal rods must be taken into account in treatment planning calculations.
Abstract
Background
Metal spinal rods are used as fixation devices in spinal surgery. The attenuation effect of these rods has not been completely studied for patients with spinal rods and requiring spinal radiotherapy.
Aim
The purpose of the current study was to investigate the dosimetric perturbation effect of metallic spinal rods in different photon beams.
Materials/Methods
Three photon beams of 6, 9 and 15MV were modelled using MCNP4C Monte Carlo (MC) code. The geometry consisted of two spinal rods at a depth of 4cm and a water phantom was used for MC calculations. The beam profiles at depths of 5.5, 6.5 and 7.5cm were calculated.
Results
Dose reductions of 10.2–11.2% and 5–6.2% were observed for steel and titanium rods respectively. The insertion of metallic rods into the photon beams did not change the spinal cord received dose but the effect of both types of rods on the target region behind the rods cannot be ignored, especially for steel rods.
Conclusions
Our results suggest that for reliable spinal radiotherapy the dose attenuation effect of spinal rods must be taken into account in treatment planning calculations.
Keywords
spinal implants; spinal radiotherapy; Monte Carlo Method; dose attenuation effect
About this articleTitle
Monte Carlo study on the impact of spinal fixation rods on dose distribution in photon beams
Journal
Reports of Practical Oncology and Radiotherapy
Issue
Pages
261-266
Published online
2007-09-01
DOI
10.1016/S1507-1367(10)60064-8
Bibliographic record
Rep Pract Oncol Radiother 2007;12(5):261-266.
Keywords
spinal implants
spinal radiotherapy
Monte Carlo Method
dose attenuation effect
Authors
Asghar Mesbahi
Farshad Seyed Nejad