Respiratory motion effect on tumor and normal tissue doses in patients with lung cancer, treated with Intensity Modulation Radiation Therapy and Three Dimensional Conformal Radiation Therapy.

Abstract

<strong>Introduction</strong>:

The aim of this study is to investigate the effect of respiratory motion during radiation therapy in patient with lung cancer and comparison of dosimetric parameters between Intensity modulation radiation therapy and three-dimensional conformal radiotherapy in lung cancer.

<strong>Materials and Methods:</strong>

Two CT scan was performred for each patient. Once in inspiration and once in Expiration mode and the images fused together. GTV and CTV were contoured in two modes. The CTVs combined and by increasing the 10 millimetres margin, the PTV was made. An IMRT plan and a 3DCRT plan for each patient were performed. The plans comparison was based on dose- volume histogram. Organ at risk sparing, HI, CI were analysed.

<strong>Results:</strong> V20 of Lung (P=0.043) were lower in IMRT than the 3DCRT plans. The maximum dose of spinal cord (P=0.043) were lower in 3D-CRT than IMRT plans. HI (P=NS) and CI(P=NS) had no significant difference in 3D-CRT and IMRT plans. <strong>Conclusion:</strong> The IMRT technique, in addition to optimizing the dose distribution, reduces lung doses and prevents the occurrence of radiation pneumonia. Also, the method used in this study can be a substitute for 4DCT in treatment centers that are not equipped with this technique.