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Objective:To compare the dosimetry of three-dimensional conformal radiotherapy (3D-CRT), intensity modulated radiotherapy (IMRT) and simplified intensity modulated radiotherapy (sIMRT) for hepato-cellular cancer, in order to put forward the best radiation therapy plan. Methods:10 patients with hepatocellular carcinoma were designed 4 fields radiotherapy plan of 3D-CRT, IMRT and sIMRT, prescribed dose 50 Gy/20f, compared the target dose of homogeneity index (HI) and conformal index, monitor unit (MU), the dose of organ at risk (OAR) of the 3 different radiotherapy techniques. Results: Compared sIMRT respectively with 3DCRT and IMRT, target optimum conformal index IMRT was the optimal, sIMRT was the second, and 3D-CRT was the worst. The differences were statistically significant among them (t=4.95, t=4.32;P<0.05). Target homogeneity index IMRT was the optimal, sIMRT was the second, and 3D-CRT was the worst. The differences were statistically significant among them (t=3.42, t=4.02;P<0.05 statistically significant). The low dose irradiation area of normal liver, time of therapy, the child field number, the total MU and the protection of OAR:3D-CRT
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Objective To investigate the feasibility of simplified intensity-modulated radiotherapy (sIMRT) and concurrent chemotherapy against neck and upper thoracic esophageal carcinoma with lymph node metastasis.Methods sIMRT plans were designed for 44 patients of neck and upper thoracic esophageal carcinoma with lymph node metastasis, 20 of which underwent high dose sIMRT (hsIMRT group) and 24 underwent conventional dose sIM RT (csIMRT group).Three target volumes were defined:PGTVnd, target volume of lymph node lesion, irradiated to 68.1 Gy ( 2.27 Gy × 30 fractions ) for the hsIMRT group, and 60 Gy (2.0 Gy ×30 fractions) the csIMRT group; PTV1, the target volume of primary lesion, to be irradiate to 63.9 Gy (2.13 Gy × 30 fractions) for the hsIMRT group and 60 Gy (2.0 Gy × 30fractions) for the csIMRT group; PTV2 , the prophylacticly irradiated volume, to be irradiated to 54 Gy (1.8 Gy ×30) for both groups.The sIMRT plan included 5 equiangular coplanar beams.All patients received DDP + 5-FU regimen concurrently with radiotherapy at 1 -5 d and 29- 33 d, respectively.Chemotherapy was repeated for two cycles 28 days after the radiotherapy was finished.Results The treatment was completed for all patients within 6 weeks.During the treatment only one patient with grade 3 acute bronchitis was observed in the hsIMRT group.The complete response (CR) rate for the lymph node lesion of the hsIMRT group was 75% ( 15/20 ), significantly higher than that of the csIMRT group [45.8% ( 11/24), x2 = 3.84, P ＜ 0.05].The 1-, 2-, and 3-year progression-free survival rates of the hsIMRT group were 60%, 40%, and 25% , respectively,all significantly higher than those of the csIMRT group (41.7%, 25%, and 8.3% respectively, x2 = 4.11,P ＜ 0.05).However, there were not significant differences in the total survival rate, and the CR and PR of the esophageal lesion between these 2 groups.The major toxicity observed was grade Ⅰ -Ⅱ leukoctyopenia.Conclusions sIMRT generates desirable dose distribution for neck and upper thoracic esophageal carcinoma.hsIMRT has a better short-term efficacy than csIMRT.High dose radiotherapy toward metastatic lymph nodes helps increase progression-free survival.
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Objective To study the dynamic changes of anatomy and the dosimeter distribution those changes influenced. Methods Initially simplified intensity modulated radiation therapy (sIMRT)were performed to twenty-nine patients with phase Ⅲ - Ⅳa esophageal carcinoma from January 2007 to March 2009. The target volumes and involving organs were contoured on the primary spiral CT pictures.After sIMRT planning being finished, secondary CT scan was acquired to rectify the treatment center. For eleven patients at every other week and eighteen patients at the fourth week, spiral CT images were acquired according to the same treatment center, and thereafter fused with the first CT images. Firstly, the law of change and the best time of replanning were searched:the changed gross tumor volume (GTV), gross node volume (GTVnd), plan target volume (PTV) and normal organs (lung, spinal cord, heart and outline) on the fusion interface were modified by a single physician, the changes for each structure throughout treatment were measured by system software. Secondly, dose distributions were computed and evaluated for replanning CT using the same beams arrangement as the initial plan. Cumulative dose was estimated using weighted average and compared with the original plan. Results For eleven patients, The law of change:the volume of outlines and GTV gradually decreased, and the change come to peak in the fourth week. The conformal index for PTV gradually decreased, whereas the heterogeneous index gradually increased. For twenty-nine patients on the fourth week, the dose of GTV were more than 60 Gy. The dose of PTV-D95 and CTV-D99 decreased ( t = 1.49, P = 0. 147 and t = 2. 07, P = 0. 048 respectively). The dose of CTV-D99 in two patients deceased to 54 Gy or less. The cord-Dmax and lung V30 increased significantly ( t = - 2. 42, P = 0. 022 and t = -2. 26,P =0. 032). Conclusions During the course of sIMRT for esophageal cancer, the volume of GTV decreased and the change come to peak in the fourth week. It is the best time for evaluating the change of dose of target volume using CT-CT fusion. For some patients, revise of the treatment plan is needed to ensure adequate target volume dosage and safety of normal tissues.
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Objective To compare the dosimetry difference among three-dimensional conformal radiotherapy (3 DCRT),simplified intensity-modulated radiotherapy (sIMRT) and intensity-modulated radiotherapy (IMRT) in whole pelvic irradiation in postoperative rectal carcinoma,in order to optimize the protocol for clinical practice.Methods From 2006 to 2008,10 patients with stage II and ID rectal cancer after radical resection (Dixon surgery) participated in this study.3DCRT,sIMRT and IMRT were performed for each patient.The dose distribution of target volume and normal tissues,conformal index (CI) and HI were analyzed using the dose-volume histogram (DVH).Results The CI for PTV of IMRT and sIMRT was superior to that of 3DCRT.3DCRT had the best HI in PTV target area dose distribution,while IMRT was similar with sIMRT,however,there were no significant difference among them.As regarded as the protection on organs at risk,for bladder,IMRT was superior to 3DCRT and slightly better than sIMRT;for small intestine,sIMRT showed better performance than 3DCRT while IMRT was better than sIMRT but with no significant difference;for colon,no dosimetry difference was found among three plans;for caput femoris,IMRT and sIMRT were better than 3DCRT.Additionally,sIMRT was similar to 3DCRT in MU of segments,but significantly lower than IMRT.The mean values of total MU for 3DCRT,sIMRT and IMRT were 569.73 ±48.69,542.97 ±69.78,and 770.25 ±73.12,respectively.Conclusions All of 3DCRT,sIMRT and IMRT could provide target area with sufficient and accurate dose,meanwhile they could also protect organs at risk well on rectal cancer after radical resection.Compared with 3DCRT plan and IMRT plan,sIMRT plan might be the optimal plan for clinical practice.
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ce, sIMRT and IMRT radiotherapy techniques can protect the lung and spinal cord well.
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Objective To compare the homogeneity and conformity of dose distribution in the target and the dose to the organs at risk among 3-dimensional conformal radiation therapy (3DCRT), intensity modulated radiation therapy (IMRT) and simplified intensity modulated radiation therapy (sIMRT), and then to evaluate the clinical value of sIMRT for cervical cancer. Methods Ten patients with cervical canc-er receiving radical radiotherapy and brachytherapy were enrolled. Before radiotherapy, CT was performed and target volumes were delineated. The clinical target volume (CTV) included supravaginal portion, cervi-cal stump, paracervical tissue, common iliac lymph nodes, internal and external iliac lymph nodes, obtura-tor lymph nodes, sacral lymph nodes, and the surrounding tissues. If the vagina was involved, the target vol-ume included the whole vagina. Margins between planning target volume (PTV) and CTV were 10 mm in the anterior direction, and 5 mm in other directions. The prescribed dose was 95% PTV receiving 45 Gy in 25 fractions of 1.8 Gy. The dose volume histogram, conformity index, homogeneity index and treatment time per faction were compared. Results Among the three radiotherapy techniques, 3DCRT had the best homo-geneity of dose distribution, while there was no significant difference between IMRT and slMRT. According to the conformity of dose distribution, sIMRT was better than 3DCRT, but worse than IMRT. Comparing the bladder sparing, IMRT was the best followed by sIMRT. The volume of the small intestine receiving high dose was increased significantly with slMRT when compared with IMRT. And the treatment time per faction was4, 10 and 18 minutes for3 DCRT, sIMRT and IMRT, respectively. Conclusions sIMRT could re-duce the work intensity of the staff, shorten the treatment time per fraction, and simplify the authenticate procedure, which is cost-effective and suitable in the treatment of cervical cancer.
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Objective To evaluate the dose distribution of target volume and normal tissues with different treatment planning such as three dimensional conformal radiotherapy(3DCRT) ,simplified intensity modulated radiotherapy(sIMRT) ,and intensity modulated radiotherapy (IMRT) for patients with radically resected rectal cancer. Methods Ten male patients with stage Ⅱ and Ⅲ rectal cancer after radical resection (Dixon surgery) were enrolled in this study. 3-field or 5-field 3DCRT,slMRT and 5-field or 7-field IMRT plans were performed for each patient. The dose distributions of target volume and normal tissues,conformal index(CI) and heterogeneous index(HI) were analyzed using the dose-volume histogram(Dvit). The prescription dose was 50 Gy in 25 fractions. Results The CI for PTV of IMRT and sIMRT was superior to 3DCRT. Conversely,the HI for PTV of 3DCRT was superior to sIMRT and IMRT. sIMRT and IMRT can protect the organs at risk better than 3DCRT. The mean of total MU for 3DCRT3f,3DCRT5f, sIMRT, IMRT5f and IMRTT7f was 482±13,504±11,455±42,841±36 and 884±46, respectively. Conclusions Comparing with 3DCRT plans and IMRT plans, sIMRT plan was the optimal plan for clinical practice. All of the three radiotherapy techniques can protect the rectal stump and anal canal well with the prescription dose of 50 Gy.