- Title
- Implications for dosimetric changes when introducing MR-guided brachytherapy for small volume cervix cancer: a comparison of CT and MR-based treatments in a single centre
- Creator
- Dempsey, Claire; Govindarajulu, Geetha; Sridharan, Swetha; Capp, Anne; O'Brien, Peter
- Relation
- Australasian Physical & Engineering Sciences in Medicine Vol. 37, Issue 4, p. 705-712
- Publisher Link
- http://dx.doi.org/10.1007/s13246-014-0307-4
- Publisher
- Springer Netherlands
- Resource Type
- journal article
- Date
- 2014
- Description
- To evaluate cervix brachytherapy dosimetry with the introduction of magnetic resonance (MR) based treatment planning and volumetric prescriptions and propose a method for plan evaluation in the transition period. The treatment records of 69 patients were reviewed retrospectively. Forty one patients were treated using computed tomography (CT)-based, Point A-based prescriptions and 28 patients were treated using magnetic resonance (MR)-based, volumetric prescriptions. Plans were assessed for dose to Point A and organs at risk (OAR) with additional high-risk clinical target volume (HR-CTV) dose assessment for MR-based brachytherapy plans. ICRU-38 point doses and GEC-ESTRO recommended volumetric doses (D2cc for OAR and D₁₀₀, D₉₈ and D₉₀ for HR-CTV) were also considered. For patients with small HR-CTV sizes, introduction of MR-based volumetric brachytherapy produced a change in dose delivered to Point A and OAR. Point A doses fell by 4.8 Gy (p = 0.0002) and ICRU and D2cc doses for OAR also reduced (p < 0.01). Mean Point A doses for MR-based brachytherapy treatment plans were closer to those of HR-CTV D₁₀₀ for volumes less than 20 cm³ and HR-CTV D₉₈ for volumes between 20 and 35 cm³, with a significant difference (p < 0.0001) between Point A and HR-CTV D₉₀ doses in these ranges. In order to maintain brachytherapy dose consistency across varying HR-CTV sizes there must be a relationship between the volume of the HR-CTV and the prescription dose. Rather than adopting a ‘one size fits all’ approach during the transition to volume-based prescriptions, this audit has shown that separating prescription volumes into HR-CTV size categories of less than 20 cm³, between 20 and 35 cm³, and more than 35 cm³ the HR-CTV can provide dose uniformity across all volumes and can be directly linked to traditional Point A prescriptions.
- Subject
- cervix; HR-CTV; prescription; audit
- Identifier
- http://hdl.handle.net/1959.13/1301491
- Identifier
- uon:20297
- Identifier
- ISSN:0158-9938
- Language
- eng
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