Dosimetry Research Of CT-guided High Dose Rate Intracavitary Brachytherapy For Esophageal Carcinoma

The study is based on CT images based positioning, esophageal cancerbrachytherapy applicators are planning to use a different implementation of comparativeanalysis and follow-up radiation toxicities related to dose assessment results of theanalysis parameters, combined with different doses of the reference point distancesettings, further dose assessment parameters were analyzed. The purpose of the clinicalfacilities recommended more adaptable and more consistent source of dose assessmentrequirements of the reference point for the individual esophageal cancer brachytherapyradiotherapy.Firstly, using different applicator esophageal intracavitary dosimetry study.Selection of patients included30cases of pathologically confirmed esophageal cancer,after external beam radiotherapy for post afterloading intracavitary radiotherapy patients,randomly divided into three groups, respectively with conventional balloon applicator,applicator, improved applicator of esophageal cancer by CT guided brachytherapyplanning design and production. Then the dose parameters for the above three groups ofapplicator after loading plan for statistics, including tumor target volume dose of D80,D90, D100, DMin, DMax, DMean, ultra high dose volume HD, conformal factor CI, averageHI, esophageal mucosal DMax, spinal cord DMax, double mean lung dose MLD. Theacute and late esophageal radiotherapy and the corresponding statistical reaction.Through the research, the application of balloon type applicator will change thedischarge cavity dose distribution, dose related significantly influence target evaluationparameter. The use of bag type applicator, because of considering the dose evaluationparameters, select the appropriate reference point distance after loading therapy.Improved fixed diameter2.2mm applicator for intracavitary afterloading radiotherapydose distribution in conventional applicator, apply to the external radiation therapy,tumor shrinking significantly, invasive depth <1.5cm, the lesion length of <6cm andfree from distant metastasis of esophageal cancer patients with intracavitary therapy,intracavitary therapy suggest that combination of CT positioning of esophagus cancer.Then the study dose distribution of esophageal intracavitary reference pointdistance. Selection of improved applicator group10cases30times after loading plan, setting a three dose reference point and different distance, the other parameters constant,3D afterloading planning design. The study found that the routine use of1.0cm from thesource as a prescription dose reference point is reasonable, in esophageal cancer afterloading with dose distribution of target better treatment. Can also be used in the externalbeam radiotherapy set reference point volume radius method, tumor shrinkingsignificantly, invasive depth <1.5cm, the lesion length of <6cm and free from distantmetastasis of esophageal cancer patients with intracavitary afterloading therapy, butneed to support volume calculation combined with CT imaging and3D afterloadingplanning system. The maximum transverse diameter method set reference point is tomake the tumor edge as much as possible to achieve the prescribed dose and improvelocal dose in the target region, but will increase the dose of esophagus mucousmembrane, thus subject to reasonable assessment can be applied to esophagealintracavitary therapy.