Analisis Dosis Serap Organ Kritis Lensa Mata pada Terapi Karsinoma Nasofaring dengan Pesawat Linear Acelerator (Linac) dan Blok Plumbum

Abstract

Nasopharyng cancer is a malignant that anatomically has a definite border at the nasopharyng area. The closest clinical organs and are in the irradiated field are the eyes, the tolerance dose for the eye lens is 500 cGy on the TD 5/5 (complication occurred no more than 5 % within 5 years). One of the methods to treat the nasopharyng cancer is by using Linear Acelerator (LINAC) equipment and the auxiliary instruments, such as lead block. The irradiated method used is 3 irradiated fields method ( 2 latero-lateral fields and 1 antero-posterior field). The experiment was using 66 pieces of thermoluminescent dosimeters (TLDs) that were placed on the right and left eye lens 3 pieces each with 11 times of irradiation using the 200 cGy fractionation. By doing the variance analysis (ANOVA), it is known that the mean of those 6 pieces of TLDs are the same or identical. So then the experiment continued with the frequency statistical analysis the results the data of absorbed dose in the eye lens is 11,066 ± 1,315 cGy for each 200 cGy fractionation. If the mean absorbed dose in the eye lens multiplied by 25 times of fractionation to fulfill the 5000 cGy irradiation dose, it’s found that the absorbed dose taken by the eye lens is 243,775 – 309,525 cGy. This results show that the absorbed dose taken by the eye lens ( both right and left) is still under the 500 cGy tolerance dose for eye lens.