Dosimetric Comparison of Volumetric Modulated Arc Therapy, Static Field Intensity Modulated Radiation Therapy, and 3D Conformal Planning for the Treatment of a Right-Sided Reconstructed Chest Wall and Regional Nodal Case

We compared 3D conformal planning, static field intensity modulated radiation therapy (IMRT), and volumetric modulated arc therapy (VMAT) to investigate the suitable treatment plan and delivery method for a right-sided reconstructed chest wall and nodal case. The dose prescribed for the reconstructed chest wall and regional nodes was 50.4 Gy. Plans were compared for target coverage and doses of the lungs, heart, contralateral breast, and healthy tissue. All plans achieved acceptable coverage of the target and IMNs. The best right lung sparing achieved with 3D was a V20 Gy of 31.09%. Compared to it, VMAT reduced the same by 10.85% and improved the CI and HI over 3D by 18.75% and 2%, respectively. The ipsilateral lung V5 Gy to V20 Gy decreased with VMAT over IMRT by as high as 17.1%. The contralateral lung V5 Gy was also lowered with VMAT compared to IMRT by 16.22%. The MU and treatment beams were lowered with VMAT over IMRT by 30% and 10, respectively, decreasing the treatment time by >50%. VMAT was the treatment plan and delivery method of choice for this case due to a combination of improved lung sparing and reduced treatment time without compromising target coverage.

Download Full-text

Dosimetric comparison of volumetric modulated arc therapy and intensity modulated radiation therapy for anal cancer

Journal of Radiotherapy in Practice ◽

10.1017/s1460396919000475 ◽

2019 ◽

Vol 19 (2) ◽

pp. 190-192

Author(s):

Bing-Hao Chiang ◽

Kerry Hibbitts ◽

Heather Ortega ◽

Terence Herman ◽

Salahuddin Ahmad

Keyword(s):

Radiation Therapy ◽

Treatment Time ◽

Treatment Plan ◽

Volumetric Modulated Arc Therapy ◽

Anal Carcinoma ◽

Intensity Modulated Radiation Therapy ◽

Patient Comfort ◽

Dose Volume Histograms ◽

Intensity Modulated ◽

Arc Therapy

AbstractAim:Volumetric modulated arc therapy (VMAT), an extension of intensity modulated radiation therapy (IMRT), employs modifications in gantry rotation speed, machine dose rate and multi-leaf collimator motion to deliver a three-dimensional dose distribution. This study compared VMAT to IMRT for patients with anal carcinoma.Materials and Methods:Sixteen patients previously treated with IMRT were retrospectively selected. Each patient received a total dose of 57·6–63·0 Gy in 1·8 Gy fractions. A single- or double-isocenter multi-arc VMAT treatment plan was generated using Eclipse RapidArc system with the same computed tomography image sets and optimisation constraints used for IMRT. Dose–volume histograms (DVHs) for planning target volumes (PTVs) and organs at risk (OARs), and monitor units (MUs) and beam on times (BOTs) were used for comparison. Results:IMRT and VMAT plans showed insignificant differences in PTV homogeneity and conformity and sparing hips and bowel. VMAT required fewer mean MU and shorter BOT per plan (1,597 MU, 2·66 min) compared to IMRT (2,571 MU, 4·29 min) with p < 0·0001. Conclusions:Fewer MU and shorter BOT for VMAT may decrease the damage from secondary radiation and treatment delivery uncertainty due to intra-fraction tumour motion, leading to higher machine throughput and improving patient comfort, with less treatment time.

Download Full-text