Dosimetry Comparison Among Helical Tomotherapy, Intensity Modulaiton Radiaiton Therapy And Three-dimensional Conformal Radiation Therapy Plan For Mulitple Brain Metastases

Objective: To evaluate the dosimetry characteristics of three treatmenttechniques for brain metastases through comparing and analyzing the helicaltomotherapy (HT), intensity modulation radiotherapy (IMRT) and three-dimensional conformal radiotherapy (3D-CRT) plans, and subsequently to providescientific basis for clinical application of different treatment techniques.Methods: CT/MRI images of40patients with one, two, three and multiplebrain lesions were chosen for retrospective analysis. The target volumes andnormal organs were contoured and transferred to Precise plan, Pinnacle8.0m andHI planning system respectively. The prescribed dose of whole brain (PTVwb) wasgiven at40Gy in20fractions, while the doses to brain metastases (pGTVs) weresimultaneously boosted to60Gy. Then3D-CRT and IMRT and HI plan weredesigned by physicist respectively. Plans were compared regarding homogeneityindex (HI), conformal index (CI), dose volume histogram(DVH), and otherdosimetric index.Results: All plans could meet the needs of the prescribed dose and thedosimetric limits of critical organs. The dose distribution, conformity anduniformity of HT plans were better than those of IMRT and3D-CRT plans (P＜0.05). The maximum dose for the lenses above3brain metastases of HT planswere lower than those of IMRT and3D-CRT plans (P＜0.05). The maximum andmean dose for the middle ears, inner ears, optic nerves in1～2brain metastasesand the brain stem above3brain metastases of HT plans were lower than those of3D-CRT plans (P＜0.05). The dose distribution, conformity, uniformity of PTVwbof IMRT plans were better than those of3D-CRT plans (P＜0.05), especially forthose with over3brain metastases. The maximum and mean dose for the middleears, optic nerves in1～2brain metastases and the brain stem above3brainmetastases of IMRT plans were lower than those of3D-CRT plans (P＜0.05).The dose uniformity of pGTVsof3D-CRT plans were better than those of IMRT plans (P＜0.05), especially for those with over3brain metastases. The maximumdose for the eyes and lenses in1～2brain metastases of3D-CRT plans werelower than those of HT and IMRT plans (P＜0.05). As for the low-dose volumeoutside pGTVsand high-dosevolume in the PTVwb, HT plans were smaller thanthose of IMRT plans, and IMRT plans were smaller than that of3D-CRT plans.Conclusion: Three plans can meet the needs of the prescribed dose and thedosimetric limits of critical organs. HT plans have better dose uniformity andconformality than IMRT plans for brain metastases, while the IMRT plans arebetter than3D-CRT plans, especially for those with over3brain metastases. Objective: To evaluate the curative effect and adverse effects ofthree-dimensional conformal radiotherapy (3D-CRT) for patients with brainmetastases from non-small-cell lung cancer.Methods:65cases of brain metastatic tumors from non-small-cell lungcancer were delivered with by3D-CRT. The patients were treated by whole brainradiotherapy (DT40～50Gy2Gy/fraction,5times/week) with simultaneousintegrated boost to multiple brain metastases (DT60Gy,2Gy/fraction,5times/week). Or at first the dose of whole brain was40Gy (2Gy/fraction,5times/week) and then the dose of the multiple brain metastases was20Gy(2Gy/fraction,5times/week). The curative effect and toxicities were evaluatedafter treatment.Results: All patients were followed up for2～35months (median12months). CR was observed in the4cases (6.15%), PR23cases (35.38%), SD33cases (50.77%), PD5cases (7.69%), the clinical response rate was41.54%．1and2year survival rates were52.31%and12.31%respectively. The main toxicitieswere radiation-induced cerebral edema, acratia, marrow suppression, alopecia,impaired memory and III～IV nervous system side effects.Conclusion:3D-CRT for brain metastatic tumors from non-small-cell lungcancer can improve the local control rate and prolong the survival time with fewadverse effects. No differences in overall survival or symptom control has beendemonstrated among the common fractionation schemes with boost to multiplebrain metastases. The patients with high GPA have longer survival, for they canbenefit from treatments. On the contrary, the patients have shorter survival witholder age, lower KPS score, increased number of brain metastases and moreextracranial metastases.