Image-guided Intensity-modulated Radiotherapy In The Treatment Of Head And Neck Cancer

Objective: To investigate the image-guided radiation therapy for head and neckcancer (Image Guided Radiation Therapy, IGRT), the position error of the target area,endangering the organ dose. And analyze the toxicity of radiotherapy and short-termeffect.Method: The experimental application of the Varian23EX IGRT system to treat60patients with head and neck cancer patients, per patient per week the line KVCBCT onlineguide postural correction, positioning for the first time in intensity modulated radiotherapy(intensity modulated radiotherapy, IMRT)KV cone-beam position error correction andafter treatment, after1083times of the CT (Cone Beam CT, CBCT) scanning for the threekinds of images, respectively, match with the center of the target, calculate X (left andright), Y (Fu and bei), Z (head and feet) direction of the offset error, the moving bed datato study the position error of the target volume and OARs dose distribution. Positioningerrors, re-calculation of the dose distribution, clearly positioning error of target and organsat risk of physical dose of60head and neck cancer patients treatment planning systemsimulation. Randomized comparison intensity modulated radiation therapy patients ineach group38cases, compare IGRT group, two groups of radiotherapy toxicity in theIMRT group and short-term effect.Results:(1) To collect the first positioning CBCT totalof361times, analysis of systematic errors (mean)±random error (standard deviation) inthe X, Y, Z direction respectively (1.52±1.358) mm (1.19±0.941)mm,(1.73±1.343)mm, the error in real time correction, on the X, Y, and Z3direction systematic errors andrandom errors after correction, respectively (0.382±0.648) mm (0.437±0.574) mm(0.283±0.589) mm, below the initial position error. The average dose change (-0.72to1.41)%(2) The study measured position error, the primary tumor (GTV), left Crystal dosechange (-10.81to16.26)%, the right side of the crystal dose change (-5.08to4.25)%, theleft parotid dose range (-1.73to9.32%), the right parotid dose range (-0.73to8.9%), theoptic dose range (-1.06to2.35),changes in the spinal cord dose (-3.94to10.57)%, and thebrainstem dose change (-10.76to9.05%). The research results show that most of theorgans at risk, the average dose range of more than5%.(3) IMRT group and IGRT group were:86.8%and94.7%, and the efficiency of the difference was not statisticallysignificant (P>0.05), IGRT group compared with the IMRT group in addition to acutebone marrow suppression was no significant difference, other acute radiotherapy toxicitylight (P <0.05).Conclusion: CBCT images clearly soft tissue resolution, show patientswith tumor location, size and surrounding tissues and organs, the majority of head andneck cancer patients corrected positioning system error is significantly lower than thepre-positioning positioning system error statistical results were significant. Head and neckcancer patients better setup repeatability, positioning error is smaller, CBCT verify acertain extent, improve the accuracy of radiotherapy at the same time can minimize theadditional radiation dose, to alleviate acute radiation reaction.