Dosimetric Comparison of Lung-Sparing Radiation Therapy between Volumetric Arc Therapy and Helical Tomotherapy for Unresectable Malignant Pleural Mesothelioma

Abstract

Objective. To compare volumetric arc therapy (VMAT) and helical tomotherapy (HT) plans in terms of dosimetric parameters in positron emission tomography- (PET-) computerized tomography- (CT-) based radiation therapy planning in unresectable malignant pleural mesothelioma (MPM). Methods. CT and coregistered PET-CT data from seven patients with histologically-proven MPM were utilized for VMAT and HT plans. Target volumes and organs at risk (OARs) were delineated. The prescription doses for planning target volume 1 (PTV1) and PTV2 were 45.0 Gy and 54 Gy in 1.8 Gy/fr, respectively. Each technique was evaluated in terms of target volume coverage and OAR doses. Findings. Although the maximum (p=0.001) and mean (p<0.001) doses of PTV1, and PTV2 (p<0.001 for maximum and p=0.001 for mean doses) favored the HT technique over VMAT, both techniques efficiently covered the target volumes. Additionally, HT also provided more homogeneous dose distribution (p<0.001) and numerically lower doses received by most OARs, but again both rotational techniques were successful in keeping the OAR doses below the universally accepted limits. The major disadvantage of the HT technique was the requirement for longer treatment times (7.4 versus 2.5 minutes/fr; p<0.001) to accomplish the intended treatment. Conclusion. Results of this dosimetric comparison clearly demonstrated the possibility of safe hemithoracic irradiation of medically/technically unresectable MPM patients with either of the two rotational RT techniques, namely the VMAT and HT. Clinically, considering their poor prognosis, these promising findings may open a potential new window for curative treatment of unresectable MPM patients, if further confirmed by future clinical studies.

Dosimetric evaluation of helical tomotherapy and volumetric-modulated arc therapy for malignant pleural mesothelioma: a planning study for dose escalation

“…Herein, the target area conformity and dose uniformity of the HT treatment plan were better than those of the VMAT plan, and the dose-volume parameters of the OARs of the former were slightly lower than those of the latter. Regarding the HT plans, the V5, V10, and V20 of the ipsilateral lung, Dmean of the heart, and Dmax of the cord were 79.6%, 73.3%, 51.23%, 17.8 Gy, and 32.5 Gy, respectively, all of which were lower than the corresponding values in Pehlivan’s study ( 32 ). The V5 and V20 of the contralateral lung were 63.2% and 4.5%, respectively, higher than the corresponding values in Pehlivan’s study, while the V10 was similar in both studies.…”

GOECP/SEOR clinical guidelines on radiotherapy for malignant pleural mesothelioma

“…Pehlivan et al [ 133 ] compared VMAT and HT in patients with unresectable MPM. They concluded that both techniques offered efficient target volume coverage while maintaining OAR doses under established limits, although HT was associated with better mean and maximum doses and a significantly more homogeneous dose distribution ( P < 0.001).…”

The dosimetric and clinical comparison between helical tomotherapy and fixed-field intensity-modulated radiotherapy in radical irradiation for cervical cancer

“…With the continuous development of technology, intensity-modulated radiotherapy (IMRT) has progressed from the fixed-field to the rotational techniques like volumetric modulated arc therapy (VMAT) and helical tomotherapy (HT) (2) . Compared with the fixed-field technique, the rotational technique are featured by a high freedom in the field direction, and the protection of the normal tissues while ensuring a high dose in the tumor target volume at the same time (3)(4) . HT is a special rotational technique, which is superb in its treatment accuracy and the protection of organs at risk (OARs) (5) .…”