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Objective To compare the dosimetric difference between RapidArc and fixed gantry angle dynamic intensity modulated radiotherapy (dIMRT) in developing the pre-operative radiotherapy for rectal cancer patients.Methods Two techniques,RapidArc and dIMRT,were used respectively to develop the synchronous intensity modulated plans for 10 stage Ⅱ and Ⅲ rectal cancer patients at the dose of gross tumor volume (GTV) of 50.6 Gy divided into 22 fractions and planning target volume (PTV) of 41.8 Gy divided into 22 fractions.Both plans satisfied the condition of 95% of PTV covered by 41.8 Gy.The dose-volume histogram data,isodose distribution,monitor units,and treatment time were compared.Results The two kinds of dose volume histogram (DVH) developed by these two techniques were almost the same.The conformal indexes of GTV and PTV by RapidArc were better than those by dIMRT (t =7.643,8.226 ,P < 0.05),while the homogeneity of target volume by dIMRT was better (t =-10.065,-4.235 ,P <0.05).The dose of rectum and small bowel planned by RapidArc was significantly lower than that by dIMRT (t =2.781 ,P <0.05).There were no significant differences in the mean doses of bladder and femoral head between these two techniques.The mean monitor units of RapidArc was 475.5,fewer by 48.5% in comparison with that by the dIMRT (924.6).The treatment mean time by RapidArc was 1.2min,shorter by 79.5% in comparison with that by dIMRT (5.58 min).Conclusions There is no significant dosimetric difference between the two plans of RapidArc and dIMRT.Compared with dIMRT,RapidArc achieves equal target coverage and organs at risk(OAR) sparing while using fewer monitor units and less time during radiotherapy for patient with rectal cancer.
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Objective To compare the dosimetric difference between volumetric are modulation with RapidArc and fixed field dynamic IMRT for breast cancer radiotherapy after breast-conserving surgery.Methods Twenty patients with early left-sided breast cancer received radiotherapy after breast-conserving surgery.After target definition,treatment planning was performed by RapidAre and two fixed fields dynamic IMRT respectively on the same CT scan.The target dose distribution,homogeneity of the breast,and the irradiation dose and volume for the lungs,heart,and eontralateral breast were read in the dosevolume histogram (DVH) and compared between RapidAre and IMRT.The treatment delivery time and monitor units were also compared.Results In comparison with the IMRT planning,the homogeneity of clinical target volume (CTV) ,the volume proportion of 95% prescribed dose (V95%) was significantly higher by 0.65% in RapidAre (t =5.16,P = 0.001) ,and the V105% and V110% were lower by 10.96% and 1.48 % respectively,however,without statistical significance (t =-2.05 ,P =0.055 and t =-1.33 ,P =0.197).The conformal index of planning target volume (PTV) by the Rap~dAre planning was (0.88±0.02),significantly higher than that by the IMRT planning [(0.74±0.03),t = 18.54,P < 0.001].The homogeneity index (HI) of PTV by the RapidArc planning was 1.11±0.01,significantly lower than that by the IMRT planning (1.12±0.02,t =-2.44,P =0.02).There were no significant differences in the maximum dose (Dmax) and V20 for the ipsilateral lung between the RapidArc and IMRT planning,but the values of V10,V5 ,Dmin and Dmean by RapidArc planning were all significantly higher than those by the IMRT planning (all P < 0.01).The values of max dose and V30 for the heart were similar by both techniques,but the values of V10 and V5 by the RapidArc planning were significantly higher (by 18% and 50% ,respectively).The V5 of the contralateral breast and lung by the RapidArc planning were increased by 9.33% and 3.04% respectively compared to the IMRT planning.The mean MU of the RapidArc was 608 MU,significantly higher than that by the IMRT planning (437 MU,t = 10.86,P < 0.001).The treatment time by the RapidArc planning was 111.3 s,significantly longer than that by IMRT planning (103.6 s,t = 3.57,P = 0.002).Conclusions The RapidArc planning improves the dose distribution of CTV and homogeneity of PTV for breast cancer radiotherapy after breast-conserving surgery.However,it significantly enlarges the volume of normal tissues irradiated in low dose areas,prolongs the treatment delivery time,and increases the MU value in comparison with IMRT.
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Objective To decrease radiation induced toxicities especially mucostis in patients with locally advanced nasopharyngeal carcinoma( NPC ) who underwent concurrent radiochemotherapy, the maximum tolerated dose and dose limited toxicities of capecitabine combination with cisplatin were observed. Methods From Aug 2006 to Oct 2007, 24 patients with intensity modulated radiotherapy(IMRT) and concurrent chemotherapy with capecitabine and cisplatin for nasopharyngeal carcinoma(stages Ⅲ-Ⅳ) were enrolled in this study. There were four dose-level groups of Capecitabine[625-1250 mg/(m2 ·d) , d1-14]and fixed cisplatin dose[20 mg/(m ·d) ,d1-5) ]MRI and CT scan were used for evaluation of tumor shrinkage. Treatment related toxicities were evaluated according to the common toxicity criteria( NCI-CTC Version 3.0). Results The acute side-effects include Grade 3 or Grade 4 mucosal toxicity(lasting for at least 5 d) and Grade 3 or Grade 4 non-mucosal toxicity were evaluated. Group 625 mg/m2 and Group 825 mg/m2 had none, Group 1000 mg/m2 had 6 patients and Group 1250 mg/m2 had 3 patients for mucosal toxicity, which were the main dose-limited toxicity and relevant to the dose of capecitabine apparently( P < 0. 05 ). There was also a trend of increase by the dose level of capecitabine for other toxicities. The median follow-up time for all patients was 28. 5 months. The locoregional recurrence occurred in 2 patients and distant metastasis in 2 patients. Two-year overall survival rate and locoregional control rate were 100% and 91.7%, respectively.Complete response and partialresponse were found on MRI or CT scan in patients of 29. 2% at the end of treatment and 83. 3% after three months, respectively. Conclusions The combination regimen of capecitabine and cisplatin is safe and effective according to the preliminary result. Toxicities related to radiochemotherapy for NPC were significantly associated with the dose level of chemotherapy.
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Objective To compare the dosimetric difference between RapidArc and fixed gantry angle dynamic IMRT (dIMRT) for central-type lung cancer radiotherapy. Methods Therapy for 10 patients previously treated with dIMRT was replanned with RapidArc. Dose prescription was 66 Gy/33 fraction. Comparative endpoints were planning target volume (PTV) dose, doses to surrounding structures,number of monitor units, and treatment delivery time. Results There was no significant dosimetric difference between RapidArc and dIMRT. Compared with dIMRT, RapidArc slightly elevated target volume dose, lung V5, V10. The average values of lung V20, V30 and heart V30 were larger in dIMRT than those in RapidArc. The number of monitor units was reduced by 32% and the treatment time by 66% in RapidArc.Conclusions Both RapidArc and dIMRT plans could meet the clinical therapy needs. RapidArc could achieve similar target coverage and sparing of organs at risk, with fewer monitor units and shorter delivery time than dIMRT.
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Objective To compare the dosimetric difference of RapidArc and fixed gantry angle dynamic IMRT (dIMRT) for loco-regionally advanced nasopharyngeal carcinoma.Methods Ten previously treated patients with loco-regionally advanced nasopharyngeal carcinoma were replanned with RapidArc and dIMRT, respectively.The prescription dose was GTV 70 Gy/33 f and PTV 60 Gy/33 f.All plans met the requirement:95% of PTV was covered by 60 Gy.Dose-volume histogram data, isodose distribution, monitor units,and treatment time were compared.Results Dose distribution has no significant difference between the two techniques.RapidArc reduced the dose of the brainstem, mandible, and other normal tissues compared with dIMRT.Mean monitor units were 589.5 and 1381.0 for RapidArc and dIMRT (reduced by 57% relatively).Mean treatment time was 2.33 min and 7.82 min for RapidArc and dIMRT (reduced by 70% relatively).Conclusions Compared with dIMRT, RapidArc achieves equal target coverage and OAR sparing while using fewer monitor units and less time during radiotherapy for patient with loco-regionally advanced nasopharyngeal carcinoma.
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Objective To analyze the dosimetfic benefits, clinical effect and side-respond of whole breast using intensity modulated radiotherapy for early breast cancer after conservative surgery. Methods From Oct.2004 to Aug. 2005,103 patients received the whole breast intensity modulated radiation therapy (IMRT). A dosimetric comparison of IMRT with conventional radiotherapy (CR) was performed on each patient. The cosmetic results, clinical effect and side-respond were observed. Results The average volume proportion of 95% and 107% prescribed dose was 95.8% ± 4.90% and 84.0% ± 20.7% (t = 9.60, P < 0.01) with IMRT and CR in clinical target volume, respectively. The V20 (lung volume of aceepted> 20 Gy/all lung volume × 100%) of the ipsilateral lung were 15.70% ± 4.64% and 23. 11% ± 7.88% (t = - 13.3, P < 0.01). The V30of the heart were 4.44% ±3.93% and 15.55% ± 10.89%(t = - 11.3, P< 0.01) with IMRT and CR respectively for sixty-three left side breast cancer patients. The 1- and 2-year excellent rate of good cosmetic outcome was both 100%. The 1-, 2- and 3-year local control rate was 99% ,99% and 98% ,respectively. The 1-, 2- and 3-year disease-free survival rate was 99% ,99% and 96% ,respectively. The Grade 1 and 2 acute radiation skin reaction rate was 95.1% and 4.9%, respectively. Conclusion Compared with conventional radiotherapy, IMRT improves dose distribution of CTV and reduce the dose of normal tissue around CTV;but with better clinical effects and lower side-respond for early breast cancer patients after breast conservative surgery.
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Objective To assess the feasibility of applying intensity-modulated radiotherapy(IMRT)simultaneous integrated boost(SIB)to replace conventional radiotherapy(CR)plus brachytherapy of whole pelvis in locally advanced cervical eaneer(LACC).Methods Five LACC patients based difference position of uterus were chosen and worked out CR and IMRT SIB plans respectively.Dose distributions were compared between IMRT SIB and CR.Results When uterus was in ante-,neutral-,retro-pnsition and deviation respectively,IMRT SIB could provide enough and homogeneous dose distribution for target volume and reduce irradiated volumes and doses for organs at risk(recta,bladder and small intestine)than CR.The doses of the A,B,and fundus of uterus were higher in IMRT SIB than CR.However,in ease of small intestine was close to or encircled the uterus,the targets volume dose would be inadequacy.Conclusions LACC IMRT SIB's dose distribution is better than CR(except excess ante-position)and may help to treat those patients who couldn't be suitable with brachytherapy.
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Objective To compared intensity modulated radiation therapy (IMRT) with conventional radiotherapy(CR) for the left side breast cancer after breast-conserving surgery in regard to the homogeneity of dose in the target area, cardiac dose and irradiation volume in the target area. Methods Thirty-eight patients received inverse planning of IMRT with dynamic multi-leaf collimation (dMLC). Prescription dose was 46Gy in breast volume with X-ray, and added electron boost dose was 14Gy in the tumor bed, with a total dose of 60Gy. Clinical target volume(CTV) and heart were evaluated with dose-volume histograms(DVH) in the two plans, with the t test taken with SPSS 11.0. Results Average received dose of 95% breast volume(D 95) was (4541?34),(4517?62)cGy, volume of 105% of dose prescription(V 105%) was 17.5%?17.6%,29.4%?26.3%, while V 110% was 0.3%?0.8%,3.7%?8.2% with IMRT and CR, respectively. Received 30Gy by the heart(V 30) was 4.6%?4.3%,18.8%?12.2%(P