TO STUDY THE DURIAN SEED AS A NEW SUBSTRATE FOR BOLUS IN RADIOTHERAPY

TO STUDY THE DURIAN SEED AS A NEW SUBSTRATE FOR BOLUS IN RADIOTHERAPY

 

ABSTRACT

 

Three types of bolus are created by using three types of composition with different ratios of polyvinyl alcohol (PVA) to durian seed gums. The ratio of PVA to durian seed gum 1:9; 3:7 and 5:5.

The created bolus is characterized based on the mechanical properties such as tensile strength, strain, and flexibility. Eventually, all the bolus composition prepared have low tensile strength. A maximum tensile strength which can achieve for bolus 1:9 is 0.0827MPa, bolus 3:7 is 0.323MPa and bolus 5:5 is 0.786MPa. The strain of every type of created bolus fulfilled the minimum requirement which is more than 50%. All types of bolus have small value of the Young’s Modulus fulfilled one of bolus requirements for bolus used in radiotherapy which is less than 0.1GPa. This value is important in order to produced bolus with good flexibility.

The created bolus must have tissue equivalent properties. Hence, it is a need to measure physical density, relative electron density and transmission factor. Physical densities for bolus 1:9 is 1.06893 ± 0.00372 gcm-3 , bolus 3:7 is 1.00455 ± 0.00177gcm-3 and bolus 5:5 is 1.00415 ± 0.00127 gcm-3. The created bolus is compared with water density by using Two Sample T-test analysis. p-value for comparing bolus 1:9 with water is less than 0.05, while the comparable bolus 3:7 and bolus 5:5 with water are more than 0.05. It can be conclude that the density bolus 1:9 have significant different with water density but density bolus 3:7 and bolus 5:5 less significant difference by comparing with water density. However, by comparing all types of created bolus density with a list of commercial bolus density, the values do not show any significant

differences towards the density. Relative electron density for bolus 1:9 is 1.0282 ± 0.0192, bolus 3:7 is 1.00161 ± 0.00310 and bolus 5:5 is 1.00197 ± 0.00229. By comparing bolus 1:9 with a relative electron density of water , it shows significant difference where the p-value <0.05 whereas bolus 3:7 and bolus 5:5 show less significant differences. Transmission factor is measured by comparing created bolus with bolus which taken from Pantai Hospital, Penang. Bolus 3:7 and bolus 5:5 show less significant difference and bolus 1:9 show least significant difference by comparing the maximum depth dose at the same depth with bolus which taken from Pantai Hospital, Penang.