Weekly assessment of volumetric and dosimetric changes during volumetric modulated arc therapy of locally advanced head and neck carcinoma: Implications for adaptive radiation therapy-A prospective study

Aathira T Sreejeev; Deepa Joseph; Ajay S Krishnan; Rajesh Pasricha; Sweety Gupta; Rachit Ahuja; Nidhi Sharma; Debanjan Sikdar; Sagar Raut; Abhijith Sasi; Manoj Gupta

doi:10.1002/hed.27710

Weekly assessment of volumetric and dosimetric changes during volumetric modulated arc therapy of locally advanced head and neck carcinoma: Implications for adaptive radiation therapy-A prospective study

Head Neck. 2024 Mar 4. doi: 10.1002/hed.27710. Online ahead of print.

Authors

Affiliations

¹ Department of Radiation Oncology, AIIMS, Rishikesh, India.
² Department of Radiation Oncology, Mahamana Pandit Madan Mohan Malviya Cancer Centre, Varanasi, India.
³ Department of Radiation Oncology, AIIMS, Bhopal, India.
⁴ Department of Radiation Oncology, Shri Mahant Indiresh Hospital, Dehradun, India.
⁵ Vardhman Mahavir Medical College, New Delhi, India.

PMID: 38436506
DOI: 10.1002/hed.27710

Abstract

Background: Chemoradiation in head and neck carcinoma (HNC) shows significant anatomical resulting in erroneous dose deposition in the target or the organ at risk (OAR). Adaptive radiotherapy (ART) can overcome this. Timing of significant target and OAR changes with dosimetric impact; thus, most suitable time and frequency of ART is unclear.

Methods: This dosimetric study used prospective weekly non-contrast CT scans in 12 HNC patients (78 scans). OARs and TVs were manually contoured after registration with simulation scan. Dose overlay done on each scan without reoptimization. Dosimetric and volumetric variations assessed.

Results: Commonest site was oropharynx. Gross Tumor Volume (GTV) reduced from 47.5 ± 19.2 to 17.8 ± 10.7 cc. Nodal GTV reduced from 15.7 ± 18.8 to 4.7 ± 7.1 cc. Parotid showed mean volume loss of 35%. T stage moderately correlated with GTV regression.

Conclusion: Maximum GTV changes occurred after 3 weeks. Best time to do single fixed interval ART would be by the end of 3 weeks.

Keywords: VMAT; adaptive radiotherapy; dosimetric change; head and neck cancers; parotid shrinkage; volumetric change.