AccScience Publishing / ARNM / Volume 2 / Issue 1 / DOI: 10.36922/arnm.2784
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Assessing the adequacy of a 5-mm planning target volume margin for 4D-CT scan-based image-guided radiotherapy for locally advanced carcinoma of the lung

Animesh Saha1* Aditi Mishra1 Shreya Manna1 Ajay Banik1 Suchanda Goswami1 Jibak Bhattacharya1 Tanmoy Mukhopadhay1 Prosenjit Soren2 Sayantan Mondal2 Saptaswa Chattopadhyay2 Biplab Sarkar2 Suvra Biswal2 Kiruba George2 Mousin Gazi2 Sandipan Roy Chowdhury2
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1 Department of Radiation Oncology, Apollo Multispeciality Hospitals, Kolkata, West Bengal, India
2 Department of Medical Physics, Apollo Multispeciality Hospitals, Kolkata, West Bengal, India
Submitted: 19 January 2024 | Accepted: 12 March 2024 | Published: 27 March 2024
© 2024 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 ( )

In developed nations, 4D-computed tomography (4D-CT)-based image-guided radiotherapy (IGRT) has become the standard for treating lung carcinoma patients, with the primary goal of achieving disease cure. However, its usage in India remains limited. Here, we compared target volume delineation for radical radiation planning in patients with locally advanced lung carcinoma using helical free-breathing CT (FBCT) and 4D-CT. In addition, we assessed the adequacy of a 5-mm planning target volume (PTV) margin with 4D-CT planning. Fifty patients with locally advanced lung cancer were enrolled in the study. Each patient underwent contouring based on 4D-CT to generate an internal target volume, and a 5-mm PTV margin (PTV_4D) was added for radical radiation. Subsequently, each patient underwent two intensity-modulated radiation therapy (IMRT) plans with comparable planning and optimization parameters. One plan was based on the FBCT-based volume (PTV_3D), while the other was based on the 4D-CT-based volume (PTV_4D). PTV, organ at risk (OAR) dose, and PTV coverage by 95% of the prescribed dose (PTVD 95_3D vs. PTVD 95_4D) were compared between the two schemes. Results revealed that 4D-CT-based planning reduced PTV (mean PTV volume: 539 cc vs. 782 cc) and lowered OAR doses (mean lung dose: 13 Gy vs. 15 Gy; mean esophagus dose: 18.5 Gy vs. 21.15 Gy; mean spinal cord max dose: 35.59 Gy vs. 37.39 Gy). At 3 months after treatment imaging, 40% of the patients showed a complete response, 48% showed a partial response, 4% showed stable disease, and 8% showed progressive disease. In conclusion, 4D-CT-based radiation planning for locally advanced lung carcinoma with a reduced PTV margin of 5 mm can dramatically decrease the PTV and OAR doses without sacrificing PTV coverage compared to FBCT-based planning. However, daily online image guidance or at least a well-defined offline image guidance protocol is recommended when employing such a small PTV margin.

Lung cancer
Image-guided radiotherapy
Planning target volume
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Conflict of interest
The authors declare that they have no competing interests.
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Advances in Radiotherapy & Nuclear Medicine, Electronic ISSN: 2972-4392 Published by AccScience Publishing