Dosimetric benefits of intensity-modulated radiotherapy and volumetric-modulated arc therapy in the treatment of postoperative cervical cancer patients.

As the advantage of using complex volumetric-modulated arc therapy (VMAT) in the treatment of gynecologic cancer has not yet been fully determined, the purpose of this study was to investigate the dosimetric advantages of VMAT by comparing directly with whole pelvic conformal radiotherapy (CRT) and intensity-modulated radiotherapy (IMRT) in the treatment of 15 postoperative cervical cancer patients. Four-field CRT, seven-field IMRT, and two-arc VMAT plans were generated for each patient with identical objective functions to achieve clinically acceptable dose distribution. Target coverage and OAR sparing differences were investigated through dose-volume histogram (DVH) analysis. Nondosimtric differences between IMRT and VMAT were also compared. Target coverage presented by V95% were 88.9% ± 3.8%, 99.9% ± 0.07%, and 99.9% ± 0.1% for CRT, IMRT, and VMAT, respectively. Significant differences on conformal index (CI) and conformal number (CN) were observed with CIs of 0.37 ± 0.07, 0.55 ± 0.04, 0.61 ± 0.04, and CNs of 0.33 ± 0.06, 0.55 ± 0.04, 0.60 ± 0.04 for CRT, IMRT, and VMAT, respectively. IMRT and VMAT decreased the dose to bladder and rectum significantly compared with CRT. No significant differences on the Dmean, V45, and V30 of small bowel were observed among CRT, IMRT, and VMAT. However, VMAT (10.4 ± 4.8 vs. 19.8 ± 11.0, P = 0.004) and IMRT (12.3 ± 5.0 vs. 19.8 ± 11.0, P = 0.02) decreased V40, increased the Dmax of small bowel and the irradiation dose to femoral heads compared with CRT. VMAT irradiated less dose to bladder, rectum, small bowel and larger volume of health tissue with a lower dose (V5 and V10) compared with IMRT, although the differences were not statistical significant. In conclusion, VMAT and IMRT showed significant dosimetric advantages both on target coverage and OAR sparing compared with CRT in the treatment of postoperative cervical cancer. However, no significant difference between IMRT and VMAT was observed except for slightly better dose conformity, slightly less MU, and significant shorter delivery time achieved for VMAT.

Deng X ，Han C ，Chen S ，Xie C ，Yi J ，Zhou Y ，Zheng X ，Deng Z ，Jin X ... -  《Journal of Applied Clinical Medical Physics》

Evaluation of 3D-CRT, IMRT and VMAT radiotherapy plans for left breast cancer based on clinical dosimetric study.

This paper aims to compare dosimetric differences based on three types of radiotherapy plans for postoperative left breast cancer. In particular, based on a clinical dosimetric study, the three-dimensional conformal radiotherapy (3D-CRT), intensity- modulated radiation therapy (IMRT) and VMAT plans were implemented on 15 cases of postoperative patients with left breast cancer with prescription doses of 5000cGy. Dose volume histogram (DVH) was used to analyze each evaluation index of clinical target volume (CTV) and organs at risk (OARs). Except for homogeneous index (HI), D2, each CTV evaluation index of 3D-CRT plan was inferior to IMRT and VMAT plans (P<0.05). Compared with the VMAT plans, IMRT has a statistical significance only in Dmean, V95 (P<0.05). On the contrary, Dmean pertaining to the VMAT plan is much closer to the prescription dose with a V95 coverage rate as high as 97.44%. For the infected lung, V5, V10 of 3D-CRT were the lowest (P<0.05), while V20, V30 were the highest (P<0.05) among the three types of plans. Here, the V5, V10 of infected lung were slightly higher (P<0.05) for the VMAT and IMRT plans. Each evaluation index of the contralateral lung and heart in 3D-CRT was the lowest (P<0.05). D1 of contralateral breast was lower in both IMRT and VMAT plans, which were 1770.89±121.16cGy and 1839.92±92.77cGy, respectively. While D1 of the spinal cord in IMRT and VMAT plans was higher, which were 1990.12±61.52cGy and 1927.38±43.67cGy, respectively. When the radiation dose of 500-1500cGy was delivered to the normal tissues, 3D-CRT significantly shows the lowest volume, VMAT is relatively higher. Monitor Units (MU) and treatment time (T) of VMAT were the least, only 49.33% and 55.86% of those of IMRT. The three types of plans can meet the clinical dosimetry demands of postoperative radiotherapy for left breast cancer. The target of IMRT and VMAT plans has a better conformity, and the VMAT plan takes the advantages of less MU and treatment time.

Liu H ，Chen X ，He Z ，Li J ... -  《-》

Dosimetric advantage of volumetric modulated arc therapy in the treatment of intraocular cancer.

Deng Z ，Shen L ，Zheng X ，Zhou Y ，Yi J ，Han C ，Xie C ，Jin X ... -  《Radiation Oncology》

A dosimetric comparison of double-arc volumetric arc therapy, step-shoot intensity modulated radiotherapy and 3D-CRT for left-sided breast cancer radiotherapy after breast-conserving surgery.

Mo JC ，Huang J ，Gu WD ，Gao M ，Ning ZH ，Mu JM ，Li QL ，Pei HL ... -  《-》

[Dosimetric study of postoperative 3-dimensional conformal radiotherapy and coplanar decile intensity-modulated radiotherapy for cervical cancer].

Jiang J ，Zhang L ，Liao S ，Huagn R ... -  《-》