Examination of Jeltrate Plus as a tissue equivalent bolus material

Abstract

A product available commercially for making dental impressions, Jeltrate Plus, was evaluated as a tissue equivalent bolus material. Jeltrate Plus was found to be tissue equivalent in 6 and 15 MV photon energy beams and 6, 12, and 20 MeV electron energy beams. As a first step, different preparations for making the bolus material were investigated and an optimal mixture was determined to be two parts Jeltrate Plus powder to three parts water by weight. A suitable method for storing the material was found to be in a water filled plastic container. Since the product is fairly inexpensive and is easily and quickly made and moulded into different shapes, it is an excellent bolus material to use when treating irregular patient contours.

Figure 1

(a) Photographs of a facial mould to illustrate moldability and (b) a flat bolus slab made with a 2:3 Jeltrate®Plus powder: water mixture. The photograph on the left clearly shows the ability of Jeltrate®Plus to conform to irregular body contours. The ruler length is 15 cm.

Figure 2

Phantom geometry for electron and photon beam ionization measurements. Electron and photon data were acquired with a 100 cm SSD and SAD setup, respectively. Either Jeltrate®Plus slabs or Plastic Water® was placed on top of the chambers depending on the experiment (see text).

Figure 3

The values of ionization readings in Jeltrate®Plus relative to those in Plastic Water®, expressed as a percentage. The readings are for varying concentrations of Jeltrate®Plus powder in water (specified as the Jeltrate®Plus: water weight ratios in the legend). The data are for 6 MeV electrons.

Figure 4

Central axis depth ionization curves for 6 MeV electrons measured beyond 1.3 cm of either Jeltrate®Plus bolus or Plastic Water® for a $10\times 10{\text{cm}}^2$ field and 100 cm SSD. The data for Jeltrate®Plus bolus are expressed as a percentage of the ionization at $d_{max}$ in Plastic Water®.

Figure 5

Central axis depth ionization curves for 12 MeV electrons measured beyond 1.3 cm of either Jeltrate®Plus bolus or Plastic Water® for a $10\times 10{\text{cm}}^2$ field and 100 cm SSD. The data for Jeltrate®Plus bolus are expressed as a percentage of the ionization at $d_{max}$ in PlasticWater®.

Figure 6

Central axis depth ionization curves for 20 MeV electrons measured beyond 1.3 cm of either Jeltrate®Plus bolus or Plastic Water® for a $10\times 10{\text{cm}}^2$ field and 100 cm SSD. The data for Jeltrate®Plus bolus are expressed as a percentage of the ionization at $d_{max}$ in Plastic Water®.