Journal of Radiation and Cancer Research

ORIGINAL ARTICLE
Year
: 2016  |  Volume : 7  |  Issue : 3  |  Page : 85--89

An audit of setup reproducibility in radiotherapy of head and neck cancers


Mranalini Verma, Abdul Aziz Sait, SK Senthil Kumar, KJ Maria Das, Punita Lal, Shaleen Kumar 
 Department of Radiation Oncology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, Uttar Pradesh, India

Correspondence Address:
Punita Lal
Department of Radiation Oncology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, Uttar Pradesh
India

Background: The use of a customized immobilization thermoplastic mask is essential to compute clinical target volume (CTV) to planning target volume (PTV) margins. Purpose: The purpose of this study was to audit setup reproducibility in head and neck cancers (HNCs) since commencing an intensity modulated radiotherapy (IMRT) program. Patients and Methods: Patients for IMRT of HNC were immobilized using either a plain DQSDQ type mask (DQSDQ) or with a customized reenforced support at nasion and chin (DQSDQ-NC) or an extended DQUDQ type mask (DQUDQ- NC), for head (H) and neck (N) regions, following radiotherapy planning contrast-enhanced computed tomography scans used to generate digital reconstructed radiographs (DRRs) at 0° (anteroposterior [A-P]) and 270° (lateral) on which match structures were contoured. Orthogonal MV portal images (PIs), A-P, and lateral were obtained. PIs were matched with the DRRs to obtain the setup variations, and the systemic (∑) and random errors (σ) to calculate PTV margins using the van Herk formula (2.5∑ +0.7σ). Results: Thirty-three patients provided 226 paired PIs with matching done separately for HNC regions. PTV margins for mediolateral, A-P, and craniocaudal directions for the head region were 3, 4, and 5 mm for DQSDQ; 3, 4, and 3 mm for DQSDQ-NC; and 3, 2, and 2 mm for extended DQUDQ- NC type masks, respectively. For neck region, PTV margins were 4, 8, and 5 mm for DQSDQ; 3, 5, and 3 mm for DQSDQ-NC; and 4, 5, and 2 mm for extended DQUDQ- NC type masks. Conclusions: These audits provide the necessary confidence to decrease population-based CTV to PTV margins.


How to cite this article:
Verma M, Sait AA, Senthil Kumar S K, Maria Das K J, Lal P, Kumar S. An audit of setup reproducibility in radiotherapy of head and neck cancers.J Radiat Cancer Res 2016;7:85-89


How to cite this URL:
Verma M, Sait AA, Senthil Kumar S K, Maria Das K J, Lal P, Kumar S. An audit of setup reproducibility in radiotherapy of head and neck cancers. J Radiat Cancer Res [serial online] 2016 [cited 2019 Oct 23 ];7:85-89
Available from: http://www.journalrcr.org/article.asp?issn=2588-9273;year=2016;volume=7;issue=3;spage=85;epage=89;aulast=Verma;type=0