Dosimetric Comparison of One-, Two-, Three-, and Four-Arc Volumetric Modulated Arc Therapy Plans in Cervical Carcinoma: Evaluation of Plan Quality, Organ-at-Risk Sparing, and Treatment Efficiency.
- 1Department of Radiation Oncology, Shri Ram Murti Smarak Institute of Medical Sciences, Bareilly, IND.
Abstract
Background Volumetric modulated arc therapy (VMAT) has transformed the delivery of pelvic radiotherapy in cervical carcinoma, enabling precise dose conformity around critical organs while maintaining efficient treatment delivery. One important planning consideration that remains insufficiently explored is the optimal number of arcs required for achieving the best dosimetric outcome. This study was designed to address that question by directly comparing one-, two-, three-, and four-arc configurations within the same patient cohort. Methods Eleven patients with cervical carcinoma receiving external beam radiotherapy to 50 Gy in 25 fractions were included. Four separate VMAT plans were generated for each patient on the Eclipse treatment planning system (version 17.0.1, Varian Medical Systems, Inc., Palo Alto, CA, USA), differing only in the number of arcs employed. Plans were assessed for conformity index (CI), homogeneity index (HI), monitor unit (MU) output, and dose to the bladder, rectum, bowel, pelvic bone marrow, and bilateral femoral heads. Results Target conformity did not differ significantly across arc configurations (median CI, 0.83 for all arcs; Friedman X² = 6.0, p = 0.112). Dose homogeneity improved significantly with increasing arc number (median HI, 0.09 (one arc) to 0.06 (four arcs); Friedman X² = 18.692, p < 0.001), with Holm-adjusted post-hoc comparisons confirming significant differences for one-arc vs. four-arc (p = 0.034) and two-arc vs. four-arc (p = 0.037). MUs and bone marrow Dmean also changed significantly with arc number (MU: X² = 22.056, p < 0.001, with one-arc vs. three-arc, one-arc vs. four-arc, and two-arc vs. four-arc showing significant post-hoc differences; bone marrow Dmean: X² = 16.879, p < 0.001, with one-arc vs. four-arc and two-arc vs. four-arc showing significant post-hoc differences). Bladder D100%, bowel D195cc, planning time, and bilateral femoral head doses showed a significant overall Friedman effect; of these, only the bladder D100% (three-arc vs. four-arc) pairwise comparison remained significant after Holm correction. Bladder 50%, rectum D50%, rectum 100%, bowel D100%, and CI showed no significant overall Friedman effect. Conclusions Increasing arc number significantly improves dose homogeneity and reduces bone marrow dose at the cost of a significant increase in MUs, without compromising target conformity. Reductions in bladder, bowel, and femoral head dose, and changes in planning time, showed an overall significant arc-number effect but could not be pinned to specific pairwise comparisons after correction, with the exception of bladder D100% (three-arc vs. four-arc). Four-arc plans, and to a lesser extent, three-arc plans, offer the most favorable dosimetric profile and may be considered preferred configurations for pelvic VMAT in cervical cancer, pending confirmation in larger prospective studies.
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BibTeX
@article{priyadharshini2026dosimetric,
title = {{Dosimetric Comparison of One-, Two-, Three-, and Four-Arc Volumetric Modulated Arc Therapy Plans in Cervical Carcinoma: Evaluation of Plan Quality, Organ-at-Risk Sparing, and Treatment Efficiency.}},
author = {Priyadharshini G and Himanshi Khattar and Piyush Kumar},
journal = {Cureus},
year = {2026},
month = sep,
doi = {10.7759/cureus.116574},
url = {https://europepmc.org/article/MED/42903609},
note = {CC BY},
}
RIS
TY - JOUR
TI - Dosimetric Comparison of One-, Two-, Three-, and Four-Arc Volumetric Modulated Arc Therapy Plans in Cervical Carcinoma: Evaluation of Plan Quality, Organ-at-Risk Sparing, and Treatment Efficiency.
AU - Priyadharshini G
AU - Himanshi Khattar
AU - Piyush Kumar
PY - 2026
DA - 2026/09/20
JO - Cureus
DO - 10.7759/cureus.116574
UR - https://europepmc.org/article/MED/42903609
AB - Background Volumetric modulated arc therapy (VMAT) has transformed the delivery of pelvic radiotherapy in cervical carcinoma, enabling precise dose conformity around critical organs while maintaining efficient treatment delivery. One important planning consideration that remains insufficiently explored is the optimal number of arcs required for achieving the best dosimetric outcome. This study was designed to address that question by directly comparing one-, two-, three-, and four-arc configurations within the same patient cohort. Methods Eleven patients with cervical carcinoma receiving external beam radiotherapy to 50 Gy in 25 fractions were included. Four separate VMAT plans were generated for each patient on the Eclipse treatment planning system (version 17.0.1, Varian Medical Systems, Inc., Palo Alto, CA, USA), differing only in the number of arcs employed. Plans were assessed for conformity index (CI), homogeneity index (HI), monitor unit (MU) output, and dose to the bladder, rectum, bowel, pelvic bone marrow, and bilateral femoral heads. Results Target conformity did not differ significantly across arc configurations (median CI, 0.83 for all arcs; Friedman X² = 6.0, p = 0.112). Dose homogeneity improved significantly with increasing arc number (median HI, 0.09 (one arc) to 0.06 (four arcs); Friedman X² = 18.692, p < 0.001), with Holm-adjusted post-hoc comparisons confirming significant differences for one-arc vs. four-arc (p = 0.034) and two-arc vs. four-arc (p = 0.037). MUs and bone marrow Dmean also changed significantly with arc number (MU: X² = 22.056, p < 0.001, with one-arc vs. three-arc, one-arc vs. four-arc, and two-arc vs. four-arc showing significant post-hoc differences; bone marrow Dmean: X² = 16.879, p < 0.001, with one-arc vs. four-arc and two-arc vs. four-arc showing significant post-hoc differences). Bladder D100%, bowel D195cc, planning time, and bilateral femoral head doses showed a significant overall Friedman effect; of these, only the bladder D100% (three-arc vs. four-arc) pairwise comparison remained significant after Holm correction. Bladder 50%, rectum D50%, rectum 100%, bowel D100%, and CI showed no significant overall Friedman effect. Conclusions Increasing arc number significantly improves dose homogeneity and reduces bone marrow dose at the cost of a significant increase in MUs, without compromising target conformity. Reductions in bladder, bowel, and femoral head dose, and changes in planning time, showed an overall significant arc-number effect but could not be pinned to specific pairwise comparisons after correction, with the exception of bladder D100% (three-arc vs. four-arc). Four-arc plans, and to a lesser extent, three-arc plans, offer the most favorable dosimetric profile and may be considered preferred configurations for pelvic VMAT in cervical cancer, pending confirmation in larger prospective studies.
SN - 2168-8184
ER -