The superiority of hybrid-volumetric arc therapy (VMAT) technique over double arcs VMAT and 3D-conformal technique in the treatment of locally advanced non-small cell lung cancer--a planning study.

To compare the dosimetric performance of three different treatment techniques - conformal radiotherapy (CRT), double arcs volumetric modulated arc therapy (RapidArc, RA) and Hybrid-RapidArc (H-RA) for locally-advanced non-small cell lung cancer (NSCLC). CRT, RA and H-RA plans were optimized for 24 stage III NSCLC patients. The target prescription dose was 60Gy. CRT consisted of 5-7 coplanar fields, while RA comprised of two 204(o) arcs. H-RA referred to two 204(o) arcs plus 2 static fields, which accounted for approximately half of the total dose. The plans were optimized to fulfill the departmental plan acceptance criteria. RA and H-RA yielded a 20% better conformity compared with CRT. Lung volume receiving >20Gy (V20) and mean lung dose (MLD) were the lowest in H-RA (V20 1.7% and 2.1% lower, MLD 0.59Gy and 0.41Gy lower than CRT & RA respectively) without jeopardizing the low-dose lung volume (V5). H-RA plans gave the lowest mean maximum spinal cord dose (34.4Gy, 3.9Gy<CRT and 2.2Gy<RA plans) and NTCP of lung. Higher average MU per fraction (addition 52.4MU) was observed with a reduced treatment time compared with CRT plans. The H-RA technique was superior in dosimetric outcomes for treating locally-advanced NSCLC compared to CRT and RA.

Chan OS ，Lee MC ，Hung AW ，Chang AT ，Yeung RM ，Lee AW ... -  《-》

Stereotactic body radiotherapy: volumetric modulated arc therapy versus 3D non-coplanar conformal radiotherapy for the treatment of early stage lung cancer.

Herbert C ，Kwa W ，Nakano S ，James K ，Moiseenko V ，Wu J ，Schellenberg D ，Liu M ... -  《-》

[Are there any dosimetric advantages in using VMAT for treatment of locally advanced non-small cell lung cancer?].

To analyse the dosimetric differences between the conventional conformal radiation therapy (CR) and the volumetric modulated arc therapy (VMAT) for non-small-cell locally advanced lung cancer (NSCLC). Two plans (CR and VMAT) were calculated for ten NSCLC patients. Dose to PTV, organs at risk and external contours (body), conformity index (PTV volume/volume of the 95% reference isodose) and homogeneity index ([maximal dose-minimal dose]/dose prescription) were compared. Doses delivered to PTV (homogeneity index, maximal, minimal and mean dose) are similar with both techniques but conformity index is improved by 60% with VMAT: from 0.55±0.07 with CR to 0.89±0.07 with VMAT (P=0.002). Pulmonary protection is improved with VMAT: with CR and VMAT, respectively, the mean lung dose is 14.1±5.2Gy and 12.2±4.5Gy, the lung volume which receives at least 30Gy (V30) is 20±8% and 14±5%, and the V20 is 24±11% and 20±10% (P=0.002). The mean dose received by the body is also 9% lower (P=0.004) and V5 is 13% higher (P=0.004) with VMAT. V10 and V15 were similar with both modalities. From 20Gy and higher, irradiated body volume is larger with CR than with VMAT. The relative difference increases with the dose: from 10% for 20Gy (P=0.014) up to 39% for 62.7Gy (P=0.002). Compared to CR, VMAT greatly improves conformity and reduces mean dose and dose delivered from 20Gy and higher to the lungs and the body.

Rousseau D ，Autret D ，Krhili S ，Yossi S ，Dupas A ，Edouard M ，Mahé MA ，Giraud P ，Le Péchoux C ，Cellier P ，Denis F ，Paumier A ... -  《-》

Volumetric modulated arc radiotherapy for esophageal cancer.

A treatment planning study was performed to evaluate the performance of volumetric arc modulation with RapidArc (RA) against 3D conformal radiation therapy (3D-CRT) and conventional intensity-modulated radiation therapy (IMRT) techniques for esophageal cancer. Computed tomgraphy scans of 10 patients were included in the study. 3D-CRT, 4-field IMRT, and single-arc and double-arc RA plans were generated with the aim to spare organs at risk (OAR) and healthy tissue while enforcing highly conformal target coverage. The planning objective was to deliver 54 Gy to the planning target volume (PTV) in 30 fractions. Plans were evaluated based on target conformity and dose-volume histograms of organs at risk (lung, spinal cord, and heart). The monitor unit (MU) and treatment delivery time were also evaluated to measure the treatment efficiency. The IMRT plan improves target conformity and spares OAR when compared with 3D-CRT. Target conformity improved with RA plans compared with IMRT. The mean lung dose was similar in all techniques. However, RA plans showed a reduction in the volume of the lung irradiated at V(₂₀Gy) and V(₃₀Gy) dose levels (range, 4.62-17.98%) compared with IMRT plans. The mean dose and D(₃₅%) of heart for the RA plans were better than the IMRT by 0.5-5.8%. Mean V(₁₀Gy) and integral dose to healthy tissue were almost similar in all techniques. But RA plans resulted in a reduced low-level dose bath (15-20 Gy) in the range of 14-16% compared with IMRT plans. The average MU needed to deliver the prescribed dose by RA technique was reduced by 20-25% compared with IMRT technique. The preliminary study on RA for esophageal cancers showed improvements in sparing OAR and healthy tissue with reduced beam-on time, whereas only double-arc RA offered improved target coverage compared with IMRT and 3D-CRT plans.

Vivekanandan N ，Sriram P ，Kumar SA ，Bhuvaneswari N ，Saranya K ... -  《-》

Dose and volume reduction for normal lung using intensity-modulated radiotherapy for advanced-stage non-small-cell lung cancer.

Murshed H ，Liu HH ，Liao Z ，Barker JL ，Wang X ，Tucker SL ，Chandra A ，Guerrero T ，Stevens C ，Chang JY ，Jeter M ，Cox JD ，Komaki R ，Mohan R ... -  《INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS》