A glass compensator filter to improve breast image quality in radiation therapy simulation

Purpose: To improve the image quality of simulation films in tangential rad iotherapy for breast cancer, we have designed a new compensator filter for the variation of breast contour using high-density-glass material. Methods and Materials: The measurements and analyses of the body contour we re done using CT scans, taken in the treatment position, of 20 breast cance r patients. The maximum tissue deficit that needed to be compensated for wa s 8 cm, and the authors fabricated the compensator system using high-densit y-glass material to maintain transparency. The glass compensator can be att ached to the accessory mount of the simulator head and its position can be easily adjusted according to breast shape and position. The image qualities of simulation films taken with and without the glass compensator in tangen tial breast radiotherapy held were compared and the him densitometry was pe rformed using the humanoid phantom. Results: Using this compensator system, the overall image quality improved, resulting in enhanced contrast and resolution of the breast simulation ima ge. The delineator wires for the beam margins were also well depicted, and the surgical clips within the breast tissue can be easily demonstrated. The film densitometry resulted in much less saturation over the breast tissue when using the glass compensator. Conclusion: Using the glass compensator system, the geographical miss may b e reduced with the virtue of the improved image quality. (C) 2000 Elsevier Science Inc.