Abstract:
Radiotherapy practices are being widely used for treatment of cancer patients in
Bangladesh. For proper treatment of cancer patient with teletherapy, percentage depth
dose and beam profile data are necessary. In the present study, central axis percentage
depth doses were determined for 60Co beam for various field sizes and depths using a'
locally fabricated solid acrylicphantom (40x50x15cm3). Dose measurements were made
atthe surface of the acrylic phantom and atthe depths ofO. 7,2.0, 3.5, 5.0, 6.5, 8.0cmfor
field si;es: 5x5 -lOxlO, l2x12, 15x15, 18 x18and 20x20cm2. An ionization chamber
(Model 23323) of volume 0.lcm3 in conjunction with a PTW UNIDOS electrometer was
used for dose measurement. The experimental data of percentage depth doses for each
field size have been analyzed by least square method and found to fit to an empirical
equation of the form y = mx+c}. The maximum deviation between the theoretical and
experimental percentage depth dose value isfound to be within :1:2.10%. In addition, the.
experimental percentage depth doses with the side of square field for particular depth
have also been fitted to an equation of the form y=aLn(x) +C2.The deviation between the
theoretical and experimental value of percentage depth dose is within :1: 0.84%. The dose
variation across the field that is the beam profile of the wCo beam for 5.0cm depth at
80cm SSD was measured for field sizes lOxlOcm2 and l5x15cm2. The beam profile data
for lOxlOcm2 field size was also performed by thermoluminecence dosimetry (TLD)
technique and compared with the data measured by ionization chamber.
Brachytherapy plays an important role in the treatment of carcinoma of the cervix at all
stages of the disease. A 137Cs low dose rate manual afterloading system is being used at
Delta Medical Center Ltd for the treatment of carcinoma of the cervix. The Manchester
system was used to characterize the doses at four points, namely: point A, point B,
bladder point and rectal point .. The dose rates at these points for different patients were
calculated by Sievert integral method Using these dose rates, dosimetry planning was
performed for the treatment of carcinoma of the cervix. From the dosimetry planning, it
is found that the bladder dose/or three patients is much higher than that of the dose
value at point A. Similarly, rectal dose is found to be higher than that of dose value at
point A for one patient. It appears that the average value of the rectal dose is
56.09:t39.29 much lower than that of bladder dose lO6.16:t22.10 for these patients, with
respect to dose value ofpoint A.
The methods used in this study could be utilizedfor treatment of cancer patient in both
teletherapy and brachytherapypractices in Bangladesh.
