What question did this study set out to answer?

This study aims to compare dosimetric outcomes of VMAT, TOMO, and IMRT in treating nasopharyngeal carcinoma.

January 18, 2026Technology in Cancer Research & Treatment3 citationsOpen Access

A Unified Planning Platform Comparison of VMAT, Helical Tomotherapy, and IMRT in Nasopharyngeal Carcinoma: Dosimetric Superiority and Organ Sparing Analysis

BHBirong HuSichuan University QMQianqian MengSichuan University XPXiaodong PengSichuan University

Key Points

This study aims to compare dosimetric outcomes of VMAT, TOMO, and IMRT in treating nasopharyngeal carcinoma.
Included 62 non-metastatic NPC patients for retrospective evaluation.
Used a unified treatment planning system for consistent dose calculations.
Performed planning with dual-arc VMAT, helical TOMO, and 9-field IMRT.
VMAT showed significantly superior homogeneity in coverage across target volumes.
Both VMAT and TOMO achieved lower doses to the brainstem and spinal cord compared to IMRT.
TOMO provided the best sparing of parotid glands, outperforming VMAT and IMRT.

Abstract

Introduction This study aimed to perform a rigorous dosimetric comparison of three advanced radiotherapy techniques—Volumetric Modulated Arc Therapy(VMAT), Helical Tomotherapy (TOMO), and Intensity-Modulated Radiation Therapy(IMRT)—for nasopharyngeal carcinoma (NPC), with particular emphasis on target coverage homogeneity, organ-at-risk (OARs) sparing, and the impact of using a unified treatment planning system (TPS) to eliminate inter-platform biases. Methods A total of 62 non-metastatic NPC patients were included in this retrospective study. All plans were re-optimized and calculated using a single TPS (RayStation 10B) with identical dose calculation algorithms to ensure comparability. Each patient underwent planning with dual-arc VMAT, helical TOMO, and 9-field IMRT techniques. Plans were evaluated based on homogeneity index (HI), conformity index (CI), and dose-volume parameters for multiple serial and parallel OARs. Statistical analyses included ANOVA with post-hoc Tukey tests. Results All techniques achieved adequate target coverage. VMAT yielded significantly superior homogeneity across all target volumes (HI = 0.06 ± 0.01 for PGTV70, p < 0.05), with no significant differences in CI among techniques. Both VMAT and TOMO significantly reduced doses to serial OARs such as the brainstem and spinal cord compared to IMRT (p < 0.05). TOMO provided the best parotid glands sparing (mean dose 26.13 ± 1.76 Gy), outperforming both VMAT and IMRT (p < 0.01). VMAT achieved the lowest brainstem mean dose (21.43 ± 4.47 Gy), while TOMO excelled in reducing high-dose volumes for most parallel OARs. Conclusion VMAT offers superior dose homogeneity and reduced delivery time, making it a highly efficient and dosimetrically favorable option for NPC radiotherapy. TOMO demonstrates advantages in sparing critical OARs, particularly in high-dose regions. The use of a unified TPS platform confirms that observed differences are technique-derived rather than planning-system artifacts. These findings support technique selection based on institutional resources and clinical priorities.

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