Dosimetric comparison between helical tomotherapy, volume modulated arc-therapy and Fixed-Field intensity modulated radiation therapy in postoperative adjuvant radiotherapy for cervical cancer

Abstract Background: To evaluate the dosimetric parameters among three different radiotherapy techniques in patients with postoperative cervical cancer, including the Helical Tomotherapy (HT), the Volume Modulated Arc-Therapy (VMAT), and the Fixed-Field intensity modulated radiation therapy (FF-IMRT). Methods: Fifteen cervical cancer patients treated with postoperative radiotherapy were re-planning with HT, VMAT and FF-IMRT. The prescribed target dose of the patients was 1.8/45Gy. The paired-samples t-test was used to compare the dosimetric parameters of the planning target and OARs (Organs at risk), and the efficiency of radiation delivery. Results: Compared with the VMAT and FF-IMRT, the HT plans showed significant improvement in the conformity index (CI) and the homogeneity index (HI). In addition, the HT plans also significantly reduced the volume of high-dose region of the OARS, especially in the V30, V40 of small bowel, rectum and bladder. Meantime, the advantage of VMAT is that it reduced the treatment time and improved the efficiency of radiation delivery obviously, compared with the HT (293.8 ± 12.8s Vs. 557.6 ± 51.9s, P < 0.001) and FF-IMRT (293.8 ± 12.8s Vs. 581.8 ± 26.1s, P < 0.001). Conclusion: Our result reveals that HT showed better CI and HI for the target and reduced high dose volumes to OARs compared with VMAT and FF-IMRT, but the lower dose volumes to OARs increased slightly. As for the benefit of VMAT, it demonstrated the shortest treatment time. Our results could provide guidance for selecting the appropriate radiation technologies for cervical cancer patients who undergoing postoperative adjuvant pelvic radiotherapy.

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Dosimetric comparison of helical tomotherapy, volume-modulated arc therapy, and fixed-field intensity-modulated radiation therapy in nasopharyngeal and cervical cancers

10.21203/rs.3.rs-45988/v1 ◽

2020 ◽

Author(s):

Deyang Yu ◽

Shan Lu ◽

Lei Wang ◽

Xueyuan Hu ◽

Xin Li ◽

...

Keyword(s):

Radiation Therapy ◽

Field Intensity ◽

Helical Tomotherapy ◽

Intensity Modulated Radiation Therapy ◽

Conformity Index ◽

High Dose ◽

Fixed Field ◽

Intensity Modulated ◽

Radiation Delivery ◽

Arc Therapy

Abstract Background: To compare the dosimetric parameters of different radiotherapy plans, helical tomotherapy(HT), volume-modulated arc therapy (VMAT), and fixed-field intensity-modulated radiation therapy (FF-IMRT) for nasopharyngeal carcinoma (NPC) and cervical cancer (CC).Methods: A total of 15 patients with NPC and 15 patients with CC were chosen for retrospective analysis and replanned for HT, VMAT, and FF-IMRT. The prescribed doses of the planning target were 2.12/69.96 Gy, 1.8/59.4 Gy for NPC and 1.8/45 Gy for CC, respectively. The dosimetric parameters of the planning target, organs at risk (OARs), and the efficiency of radiation delivery were assessed and compared using the paired-samples t-test.Results: Compared with VMAT and FF-IMRT, HT plans significantly improved the mean conformity index (CI) and homogeneity index (HI). For the OARs, the HT plans reduced the maximum doses of most organs, such as brainstem, spinal cord, and optic nerves in NPC, and significantly reduced the volume of the high-dose region in NPC and the V30 and V40 of small bowel, rectum, and bladder in CC. However, VMAT evidently reduced the treatment time and improved the efficiency of radiation delivery than HT.Conclusions: For NPC and CC, results showed that HT and VMAT possessed better homogeneity and conformity of the target and better sparing of OARs compared with the conventional FF-IMRT, and HT achieved the best effect. VMAT had the shortest radiation delivery time. The results of this study can provide guidance for the selection of appropriate radiation technologies for patients with NPC and CC who are undergoing concurrent chemoradiotherapy.

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