Investigation of the radiotherapy-related changes in the eye lens using computed tomography entropy analysis

Detection of radiotherapy-related damage in head and neck cancer patients by evaluating volumetric changes in lacrimal gland, nasolacrimal duct and computed tomography attenuation changes in lens

PURPOSE

In our study, we aimed to evaluate the change in attenuation of lens in CT images, volumetric changes, in lacrimal gland (LG) and nasolacrimal duct (NLD) of the patients receiving radiotherapy for brain or head & neck tumor. Additionally, the correlation between these changes and radiation dose data were investigated.

METHODS

Patient simulation CT images and control CT images were used to evaluate the volume and attenuation changes. Pre- and post-treatment MR and CT images were used to evaluate radiation-induced volumetric alterations in NLD and LG, respectively. Radiation therapy was given to a total dose of 54-70 Gy with conventional fractionated scheme using intensity-modulated radiotherapy technique (IMRT). Dose volume parameters were evaluated via dose volume histograms (DVHs).

RESULTS

Dose volume parameters, volume and densities of 59 lenses (L), 60 LG and 60 NLD of 30 patients were retrospectively assessed. The median LG volume was significantly lower in the post-treatment images (p < 0.001), whereas the median volumes of NLD in pre- and post-RT images were similar. The Hounsfield unit (HU) numbers of lenses were significantly lower on post-RT CT images (p < 0.001). No statistically significant correlation was found between dose parameters and volume or HU changes (p = 0.054-0.817).

CONCLUSION

It was observed that the attenuation of lenses and lacrimal gland volume significantly lowers following radiation. However, these alterations were not found to be correlated with dose.