Journal of Medical Sciences1682-44741812-5727Asian Network for Scientific Information10.3923/jms.2014.162.167KhoshgardKarim RahimiSeyed Ali 42014144Nowadays prostate cancer is the second widespread cancer among men. It is important
to use new techniques in radiation therapy of prostate cancer that make lower
exposure to normal tissues. Not withstanding the conformal radiotherapy methods
with 3-dimensional treatment planning which are known as 3-D conformal radiotherapy
and IMRT are using for radiotherapy of prostate cancer, the Co-60 Unit with
conventional 2-dimensional treatment planning is still using for radiotherapy
of prostate cancer in some of radiotherapy centers, particular in developing
countries. Therefore, this study is designed to evaluate the method that, with
using of shielding blocks and 3-D treatment planning instead of 2-D planning
for Co-60 unit therapy, is able to reduce the received dose by critical uninvolved
organs such as bladder and rectum. Both treatment planning methods were done
on a tissue-equivalent and anthropomorphic phantom in the way of equally weighted
4-field (Box method), that consist of two pairs of parallel-opposed anterioposterior
and right and left lateral beams to deliver 200 cGy to isocenter point. The
TLD-100 dosimeters were used for measuring the absorbed doses of rectum and
bladder. Cerrobend blocks for shaping each radiation field were constructed
and used in 3-D treatment planning method. The experiments were repeated five
times and absorbed dose values compared with paired student's t-test for a confidence
level of 95%. The average of measured values of received dose by bladder and
rectum in 2-D conventional treatment planning were 117.5±3.4, 120.5±4.6,
80.4±3.8 and 77±3.2 cGy, respectively, in 3-D conformal treatment
planning. The results show that use of Cerrobend blocks in 3-D conformal treatment
planning, significantly reduces the absorbed dose to critical uninvolved structures
in proportion to 2-D conventional radiotherapy of prostate cancer with using
Co-60 unit.]]>Parkin, D.M., F. Bray, J. Ferlay and P. Pisani,20055574108CDC,20012001ACS.,2007Pages: 46Pages: 46Vijayakumar, S., A. Awan, T. Karrison, H. Culbert and S. Chan et al.,199325359371Dearnaley, D.P., V.S. Khoo, A.R. Norman, L. Meyer and A. Nahum et al.,1999353267272ICRP,1975Pages: 480Pages: 480Khan, F.M.,20033rd Edn.,Pages: 560Pages: 560Kron, T.,199417175199Kron, T.,199518125Wood, J.J. and W.P. Mayles,199540309313McKinlay, A.F.,1981Pages: 270Pages: 270Khan, P.,19981st Edn.,Perez, C.A. and L.W. Brady,19973rd Edn.,Hendee, W.R., G.S. Ibbott and E.G. Hendee,20053rd Edn.,Pages: 472Pages: 472Lee, W.R., G.E. Hanks, A.L. Hanlon, T.E. Schultheiss and M.A. Hunt,199635251257Zelefsky, M.J., S.A. Leibel, P.B. Gaudin, G.J. Kutcher and N.E. Fleshner et al.,199841491500Sale, C.A., E.E. Yeoh, S. Scutter and E. Bezak,200544348354