Dosimetric characteristics of transparent bolus for external beam radiotherapy

Introduction: In radiotherapy, the bolus is often used while treating the tumor under the uneven surfaces of the patients for correcting the anatomical irregularities and increasing skin dose. Wet cotton and wet gauze are still used in developing countries, since the use of wet cotton and wet gauze has certain disadvantages, there is a need for transparent bolus which should be similar to a universally accepted bolus in terms of properties with a lower cost (50% less expensive). Material and Methods: The present study was conducted to investigate the characteristics of transparent bolus (Senflab) material, such as transmission factor, percentage depth dose (PDD), stability over time and high dose, homogeneity and transparency using 6 and 15 MV photons beam and 12, 15, and 18 MeV electrons beam. Moreover, the new bolus material was compared with those of the commercially available Superflab and RW3 slab. Results: The percentage difference in the transmission factor of Senflab was less than ±1.9%, compared with Superflab and RW3. For PDD, the percentage difference was ±2.88% and ±1.26% for photons and electron beams, respectively. The performance of bolus remained constant both physically and dosimetrically after higher dose exposure. The percentage standard deviation was 0.0002% for a period of one month, and 0.0003% for the homogeneity. The transparency of the bolus material was good enough to display the set radiation treatment field. Conclusion: This study shows the suitability of the new bolus for routine use in radiotherapy. © 2019, Mashhad University of Medical Sciences.