Comparative Study on the Surface Dose of Some Bolus Materials

Abstract

In order to investigate the possibility of using different materials as bolus in radiotherapy, five samples denoted by S2 -S6 were prepared and analyzed by comparison with one available commercial bolus denoted by S1. Sample S1 was a thermoplastic material from Qfix; S2 was a moldable silicon rubber (RTV-530 from Prochima); S3 and S4 were obtained by adding micrometric particles of Al and Cu respectively (at the same mass concentration of 5.5%); S5 was another moldable silicon rubber (GSP400 from Prochima) and S6 was a mixture of GSP400 and micrometric particles of Cu (at the mass concentration of 5.5%). The measurements of normalized transmitted dose as a function of sample thickness were performed for all samples (S1 -S6) at two values of electron beam energy (6 and 9 MeV) produced by a linear accelerator VARIAN 2100SC. The results showed that the maximum of the normalized transmitted dose of manufactured samples (S2 -S6) is registered at smaller sample thicknesses than for the analyzed commercial bolus (sample S1). The smallest sample thickness corresponding to normalized maximum point dose is obtained for sample S2 (RTV-530). Measurements performed for electron beam energy of 6 and 9 MeV have proven the possibility of using the manufactured samples as bolus in radiotherapy.

Scalp and Cranium Radiation Therapy Using Modulation (SCRUM) and Bolus

“…7 , 8 However, the ductility of thermoplastic can accommodate head circumferences slightly larger than the 57-cm template. 12 Additionally, the sheets can be trimmed for smaller head sizes, as was needed for our adult volunteer ( Fig 3 C,D). Although a single-layer bolus was used on our volunteer to demonstrate conformality, additional layers as in our patient example and for the adult head phantom may be added.…”

Evaluation of Dosimetric Properties of Handmade Bolus for Megavoltage Electron and Photon Radiation Therapy

“…In common practice, to solve the problem of dose delivery inhomogeneity in the target volume due to the irregularities of the skin surface, a material is usually added as a compensator for the missing tissue called a bolus [ 1 - 3 , 6 - 14 ]. The primary purpose of adding a bolus to radiotherapy is to increase the surface dose [ 1 , 14 ] and make the body surface anatomy as similar to a water phantom as possible so that a more homogeneous dose distribution is obtained [ 5 ].…”

“…The material used in making boluses must have some specific properties such as easy producibility, flexibility, good visibility, and it should be non-sticky, non-toxic, inexpensive and has a computed tomography number in the range of 130 to 160 HU [ 3 , 15 ]. Making bolus with material as tissue compensator is not easy to meet in the clinical standard.…”

“…Making bolus with material as tissue compensator is not easy to meet in the clinical standard. However, some previous studies have reported the use of materials that are similar to the tissue, such as aquaplast (Qfix, Orfit), gels, superflab, elasto-gel pad, dental wax, rayon blend, paraffin granules, and polypropylene [ 1 - 3 , 7 , 8 , 10 , 12 , 14 , 16 - 22 ]. The materials such as aquaplast (Qfix, Orfit), superflab, elasto-gel pad, and polypropylene are very rarely found in Indonesia and must be imported from abroad.…”

Fabrication of Alternative Bolus for Cobalt-60 Teletherapy Using Two Locally Available Materials

“…According to Walker (2005), bolus is defined as a tissue equivalent materials which when it is positioned around the irradiated area it results in an additional build up causing the maximum dose to occur at the skin surface [3]. It is required that bolus material should be innocuous, flexible, easily produced, inexpensive [4] and interact with radiation, like the part of the body it mimic or mostly like water [3,5]. It is expected that the thickness of bolus material for Cobalt-60 energy beam source should be about 0.5 cm since maximum dose usually occurs at a depth of 0.5 cm for this source [6].…”