Capability of inversely planned intensity-modulated radiotherapy delivery in Telecobalt Bhabhatron 3i Machine

© 2026 by the Author(s). This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution 4.0 International License ( https://creativecommons.org/licenses/by/4.0/ )

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Abstract

The Bhabhatron 3i (Bh 3i) is a higher-specification O-ring telecobalt machine manufactured in India. This machine has built-in multileaf collimator (MLC) vanes with high-speed motors for executing dynamic inverse planned intensity-modulated radiotherapy (IP-IMRT). This machine’s ability to deliver IP-IMRT is validated. Dosimetric measurements carried out in Bh 3i were compared to the TrueBeam Varian linac, available in another hospital. Measured radiation field analyzer data of Bh 3i were configured in the treatment planning system (TPS) on a request basis, and a temporary license was obtained from a TPS manufacturer, M/s Prowess, USA. Quality assurance measurements were carried out on the planned dose distribution for test IP-IMRT plans, downloaded from the American Association of Physicists in Medicine Task Group 119 (TG 119). MLC leakage value in Bh 3i was much lower than that of the TrueBeam linac. MLC settings remained constant in all gantry orientations. The dynamic dose delivery patterns in Bh 3i and the TrueBeam linear accelerator were similar. Static forward-planned multiple MLC field IMRT with the same isocentre produced good treatment plans. Dynamic IMRT planned on TG 119 test cases of tumor volumes demonstrated satisfactory conformality and homogeneity. Doses to organs at risk were acceptable as per norms. It was found that treatment plan goals are achievable in Bh 3i IP- IMRT, similar to the TrueBeam linac. The new Bh 3i cobalt machine can deliver IP-IMRT for cancer treatment. Obtaining a permanent license for the required TPS software is a high priority to secure the further clearances needed for clinical use.

Keywords

Bhabhatron 3i

Intensity-modulated radiotherapy

Multileaf collimator leakage

Conformal radiotherapy

Inverse planning

Funding

None.

Conflict of interest

The authors declare that there are no competing interests with any agencies, as well as among themselves.

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Advances in Radiotherapy & Nuclear Medicine, Electronic ISSN: 2972-4392 Print ISSN: 3060-8554, Published by AccScience Publishing