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Updated: Mar 21, 2026
Stereotactic Radiosurgery for Gynecologic Cancer
Published on: April 17, 2012
The dosimetric impact of target volume delineation variation for cervical cancer radiotherapy
Gemma Eminowicz1, Vasilis Rompokos1, Christopher Stacey1
1Radiotherapy Department, University College London Hospital, United Kingdom.
Background:
Cervical cancer inter-observer delineation variation has been demonstrated. This article addresses its dosimetric impact.
Methods:
21 centres outlined two INTERLACE trial quality assurance test cases. A gold standard clinical target volume (GSCTV) was created from a consensus and STAPLE outline. RapidArc plans were created for all centres' planning target volumes (PTVs; PTV1+2). Gold standard PTVs (GSPTVs) were created for each plan by applying each centre's CTV-PTV margins to GSCTV. DVH parameters including D95% and Dmean for each PTV1+2 and GSPTV were compared, representing planned versus GSPTV delivered dose. PTV1+2 and GSPTV V95% was also calculated.
Results:
Reviewing all parameters, no plans achieved acceptable GSPTV coverage. GSPTV V95%⩾95% was not achieved for any plan. GSPTV V95%<90% in 15/21 (case 1) and 14/22 (case 2) and <80% in 2 plans from both cases. GSPTV V95% is on average 10-15% lower than planned and GSPTV D95% is 10-20% lower than planned. Most common GSCTV anatomical areas not receiving 95% dose were vagina, obturator and external iliac nodes and, in case 1, the superior nodal aspect.
Conclusion:
Cervical cancer CTV delineation variation leads to significant reductions in dose delivered to GSPTV. This highlights the ongoing importance of standardising delineation in the IMRT era.
