Portal image contrast enhancement

Abstract

Aim

The delivery of radiation doses to the target volume, while minimizing the dose delivered to normal tissues, is the main objective in radiotherapy. The intention in our study was to enhance the contrast of portal images, in order to increase the accuracy of delineation of the organs in the irradiated field.

Materials/Methods

Software was written, based on local enhancements to the pixel values in the image matrix. Portal images were digitized by CCD and stored in a format compatible with this program.

We applied this program, as an m-file in a MATLAB imaging tool box, to the matrices of the portal images. The imaging parameters, before and after application of the program, were compared.

Results

Quantitative information was obtained from images. Analysis of the means, and standard deviations, of these data showed that the differences between criteria in the two groups of images were significant (p<0.01). In the case of the qualitative analysis, final images scores were based on “special weight”. The result of this test confirmed the superior quality of the post-processed images, from the professional point of view.

Conclusion

The superior final images, as judged by experts using three studied parameters (superiority of lung images, superior images of the thorax and its soft tissue), can be used to increase the accuracy of the treatment set up and therefore decrease the likelihood of complications in the normal tissues.