Comparative dosimetric analysis of IMRT and VMAT (RapidArc) in brain, head and neck, breast and prostate malignancies

Abstract

Purpose: Intensity modulated radiotherapy (IMRT) in the recent past has established itself as a gold standard for organs at risk (OAR) sparing, target coverage and dose conformity. With the advent of a rotational treatment technology such as volumetric modulated arc therapy (VMAT), an inter-comparison is warranted to address the advantages and disadvantages of each technique. Methods: Twenty patients were selected retrospectively from our patient database. Sites included were brain, head and neck, chest wall, and prostate, with five patients for each site. For all the selected patients, both the IMRT and VMAT treatment plans were generated. Plan comparison was done in terms of OAR dose, dose homogeneity index (HI), dose conformity index (CI), target coverage, low isodose volumes, monitor units (MUs), and treatment time. Results: The VMAT showed better sparing of "parotids minus planning target volume (PTV)", spinal cord and head of femur as compared to the IMRT. The lung V40 for VMAT was lower, whereas the lung V10, contralateral lung mean dose, contralateral breast mean dose and mean body dose were lower with IMRT for chest wall cases. Both the VMAT and IMRT achieved comparable HI except for the brain site, where IMRT scored over VMAT. The CI achieved by the IMRT and VMAT were similar except for chest wall cases, whereas the VMAT achieved better dose conformity. The target coverage was comparable with both the plans. The VMAT clearly scored over IMRT in terms of average MUs (486 versus 812 respectively) and average treatment time (2.54 minutes versus 5.54 minutes) per treatment session. Conclusion: The VMAT (RapidArc) has a potential to generate treatment plans for various anatomical sites which are comparable with the corresponding IMRT plans in terms of OAR sparing and plan quality parameters. The VMAT significantly reduces treatment time as compared to the IMRT, thus VMAT can increase the throughput of a busy radiotherapy department.

A Comprehensive Primer on Radiation Oncology for Non-Radiation Oncologists

“…At this point, the RO often has to choose between different techniques, as illustrated in Figure 3, which compared 3D-CRT and VMAT for the treatment of breast cancer, and Figure 4, which compared VMAT and proton therapy for the treatment of a sacral chordoma. For some cases, the choice is quite easy [78], but in some cases the choice is more difficult. Consider the case of a patient with a tumor completely in contact with the parotid gland; the choice will be between irradiating the target volume completely with the risk of inducing severe late oral dryness or better protecting the parotid gland with a higher risk of local recurrence.…”

Clinical performance of FractionLab in patient-specific quality assurance for intensity-modulated radiotherapy: a retrospective study

“…effect and reducing the radiation treatment period [1][2][3][4][5][6][7][8]. In particular, Huh et al [9] reported that the number of IMRT cases increased significantly by a factor of approximately 18 from 2011 to 2018 owing to the expansion of the national health insurance coverage in Korea.…”

Lakrimal Kese Tümörleri Tedavisi İçin VMAT ve IMRT Planlama Tekniklerinin Karşılaştırılması

“…(14). Çalışmada elde edilen MU değerleri literatür ile uyumludur (15). VMAT tekniğinin gantry rotasyonu ve ÇYK hareketlerine bağlı olarak IMRT planlarına göre daha konformal planlar ortaya çıkarabilmektedir (16).…”

“…VMAT tekniğinin gantry rotasyonu ve ÇYK hareketlerine bağlı olarak IMRT planlarına göre daha konformal planlar ortaya çıkarabilmektedir (16). Çalışmada incelenen yüksek ve orta izodoz hacimleri, VMAT planındaki 4 yarım ark'tan elde edilen daha fazla açıdan optimizasyon yapabilme kapasitesi ile IMRT plana göre daha düşük izodoz hacimlerine sahiptir (15). Elde edilen planlar için kritik organ dozları karşılaştırıldığında; beyin sapı, sağ lakrimal kese, sol optik sinir ve lens IMRT planları için daha iyi sonuç vermiştir.…”