Dosimetric Comparison For The Neck Cancer Patients Receiving 3D-CRT And IMRT

Objective:The aim of this study is to evaluate two radiotherapy plannings of the neck cancer radiotherapy with 3D-treatment planning system,to compare IMRT and 3DCRT planning in dose of target volume and protection of the spinal cord,and to obtain which technique is better.Methods:For the 12 the neck cancer parients two plannings were done with Pinnacle7.6c 3D-treatment system.The prescription dose was 55 Gy in 25 fractions of the PTVnx, The prescription dose was 50 Gy in 25 fractions of the PTVCTV.The differences of target dose and the spinal cord were compared with DVH.Result:The minimum dose of the PTVnx of 3DCRT and IMRT were 43.37±0.21Gy and 46.55±0.52GY , the mean dose were 58.54±0.32 GY and 58.15±0.43 GY, the maximum dose were 63.70±0.62GY and 59.31±0.13GY; target volume receiving 95% of the prescribed dose of the PTVnx of 3DCRT and IMRT were 80.59±47.90cm3 and 83.54±48.53cm3;The value of conformity index(CI)of the PTVnx of 3DCRT and IMRT were 0.75±0.03 and 0.92±0.06; The homogeneity index(HI) of the PTVnx of 3DCRT and IMRT were 1.19±0.05 and 1.05±0.06; The standard deviation of the dose of the PTVnx of 3DCRT and IMRT were 2.13±0.82GY and 0.54±0.02GY; The dose received by 95% PTVnx volume of 3DCRT and IMRT were 57.12±0.73Gy and 58.09±0.36 GY. The minimum dose of the PTVCTV of 3DCRT and IMRT were 42.21±0.51Gy and 44.62±0.32GY , the mean dose were 53.75±0.42 GY and 53.63±0.23 GY, the maximum dose were 64.43±0.60GY and 62.82±0.15GY; target volume receiving 95% of the prescribed dose of the PTVCTV of 3DCRT and IMRT were 80.59±47.90cm3 and 83.54±48.53cm3;The value of conformity index(CI)of the PTVCTV of 3DCRT and IMRT were 0.75±0.03 and 0.92±0.06; The homogeneity index(HI) of the PTVCTV of 3DCRT and IMRT were 1.19±0.05 and 1.05±0.06; The standard deviation of the dose of the PTVCTV of 3DCRT and IMRT were 2.13±0.82GY and 0.54±0.02GY; The dose received by 95% PTVCTV volume of 3DCRT and IMRT were 52.55±0.73Gy and 53.20±0.41 GY.The maximum dose of the the spinal cord of 3DCRT and IMRT were 60.69±3.71 Gy and 37.05±3.45 GY;the mean dose were 49.62±6.36 GY and 27.13±4.83 GY.The minimum dose and CI of the PTVnx and PTVCTV of IMRT were better than 3DCRT(P<0.05);target volume receiving 95% of the prescribed dose of the PTVnx and PTVCTV of IMRT were better than 3DCRT(P<0.05);The homogeneity index(HI)and The standard deviation of the dose of the PTVnx and PTVCTV of IMRT were lower than 3DCRT(P<0.05);the mean dose and the maximum dose of the PTVnx and PTVCTV of IMRT were lower than 3DCRT (P>0.05);target volume receiving 95% of the prescribed dose of the PTVnx and PTVCTV of IMRT were better than 3DCRT(P>0.05);The maximum dose and the mean dose of the the spinal cord of 3DCRT were higher than IMRT(P<0.05). The maximum dose and the mean dose of the the spinal cord of 3DCRT were in excess of the spinal cord tolerance,but The maximum dose and the mean dose of the the spinal cord of IMRT were in the spinal cord tolerance . Conclusion:IMRT are better to 3DCRT in conformity index and homogeneity index and dose of target volume. The maximum dose and the mean dose of the the spinal cord of 3DCRT were in excess of the spinal cord tolerance,but The maximum dose and the mean dose of the the spinal cord of IMRT were in the spinal cord tolerance .