Dosimetric analysis of volumetric modulated arc therapy and intensity modulated radiotherapy for patients undergone breast-conserving operation / 北京大学学报(医学版)

OBJECTIVE@#To compare the dosimetric differences between volumetric modulated arc therapy and intensity modulated radiotherapy for breast cancer patients after breast-conserving surgery.@*METHODS@#Ten patients who received radiotherapy after breast-conserving surgery were selected. Eclipse planning system was used to design volumetric rotating intensity-modulated (2F-RapidArc) and two field intensity-modulated radiation therapy (2F-IMRT) planning for each patient. 2F-RapidArc plans were made using two partial arcs with gantry rotation from 287°-293° to 152°-162°, and 0° to 90 ° was avoidance sector. The gantry angle of 2F-IMRT were 301°-311° and 125°-135°. The prescription dose was 46 Gy/23 fractions. All plans required 95% of the target volume receiving the prescription dose. The dose distribution of the target, organs at risk, machine unit (MU) and treatment time were compared.@*RESULTS@#2F-RapidArc and 2F-IMRT plans' uniformity index was 1.12±0.02 and 1.11±0.03 (P=0.282), respectively; conformal index was 0.80±0.03 and 0.65±0.04 (P<0.001), respectively. V110 of plan target volume was 20.98%±14.47% and 10.43%±10.49% (P=0.030), respectively. Compared with the 2F-IMRT, 2F-RapidArc plans had a higher dosimetric parameters for left lung: V5 (48.06%±17.32% vs. 24.23%±6.56%,P=0.001), V10 (28.89±9.28 vs.17.07±4.78%,P=0.004), Dmean [(9.70±2.14) Gy vs. (6.86±1.77) Gy, P=0.002], increased the double lung: V5 (22.85%±7.55% vs. 11.01%± 2.95%,P=0.001), V10 (13.16%±4.33% vs. 7.76%± 2.16%, P=0.006), Dmean [(4.66±0.95) Gy vs. (3.17±0.82) Gy, P=0.001], reduced the left lung: V40 (3.58%±1.46% vs. 6.19%±3.04%, P=0.006), reduced the double lung: V40 (1.61%±0.64% vs. 2.81%± 1.39%,P=0.005), increased cardiac: V5 (39.3%±17.19% vs. 8.79%±4.24%, P<0.001), V10 (21.31%±13.8% vs. 5.73%±3.42%, P=0.002), V20 (7.80%±6.08% vs. 4.05%±2.85%,P=0.018), Dmean [(0.64±0.25) Gy vs. (0.29±1.39) Gy,P<0.001],reduced the heart: V40(0.50%±0.40% vs. 1.86%±1.94%,P=0.037),increased the contralateral breast Dmean [(1.63±1.26) Gy vs. (0.09±0.05) Gy, P=0.004]. Compared with 2F-IMRTplan, 2F-RapidArc increased the treatment time [(132.9±7.2) s vs. (140.3±11.6) s, P=0.030]. Both the machine units were almost the same [(467.0±30.4) MU vs. (494.7±44.9) MU, P=0.094].@*CONCLUSION@#Both 2F-RapidArc and 2F-IMRT plans could reach the clinical requirements. 2F-RapidArc had a better conformal index, reduced the high dose area, but increased the low dose regions of the lung, heart, body area, and increased the average dose of the contralateral breast. The treatment time of 2F-RapidArc was longer than that of 2F-IMRT, and the MU of 2F-RapidArc and 2F-IMRT plans were almost the same.

CT guided ~(125)Ⅰseed brachytherapy for recurrent rectum cancer / 中华放射肿瘤学杂志

Objective To investigate the technological feasibility,efficacy and morbidity of cr guided ~(125)Ⅰseed implantation for recurrent rectum cancer.Methods Twenty-three patients with recurrent rectum cancer were treated with cr guided interstitial ~(125)Ⅰseed brachytherapy.In 20 patients the procedure was performed under epidural anesthesia and 3 patients under local anesthesia.Treatment planning system was used to calculate the number of seeds,the space distribution and the introduction of the seeding needles.Matched peripheral dose (MPD) of ~(125)Ⅰseed implantation ranged from 90-120 Gy for patients who had had external radiotherapy,and 140- 160Gy for those who had not.The planning target volume(PTV)was clinical target volume(CTV)plus 1 cm margin.The range of radioactivity of the ~(125)Ⅰseeds was 18.5-25.9 MBq.All these 23 patients had CT scan at 5 mm intervals after implantation for quality evaluation,together with routine chest,pelvic X-ray films within 24-48 hours after seed implantation.Three patients received three-dimensioual conformal radiation therapy(3DCRT) to a total dose of45-50 Gy,with 2-3 Gy/f.Follow-up time was from 3 to 28 months.Results All patients was able to tolerate seed implantation well.Complete pain relief was observed in 12/15,and partial relief in 2/15 and no response in 1/15,with a response rate of 93%.The local control rate was 87%.The 1-and 2-year survival rate was 93% and 50% respectively.Two of four patients have died of dissemination to the lung after 8 and 12 months. One seed has migrated into the pelvis without causing any untoward morbidity.Conclusion CT guided ~(125)Ⅰseed implantation for recurrent rectum cancer is safe,minimally invasive,causing only mild morbidity.It possesses a high efficacy,yet it should be given in combination with external beam radiation and chemotherapy,should distant metastasis be observed.