Ultrasonic mirror image from ruthenium plaque facilitates calculation of uveal melanoma treatment dose.
- Resource Type
- Academic Journal
- Authors
- Espensen CA; Department of Oncology, Section of Radiotherapy, Rigshospitalet, Copenhagen Ø, Denmark.; Department of Ophthalmology, Rigshospitalet, Copenhagen Ø, Denmark.; Jensen PK; Department of Ophthalmology, Roskilde Hospital, Roskilde, Denmark.; Fog LS; Department of Oncology, Section of Radiotherapy, Rigshospitalet, Copenhagen Ø, Denmark.; Appelt AL; Leeds Institute of Cancer & Pathology, University of Leeds and St. James's University Hospital, Leeds, UK.; Department of Oncology, Section of Radiotherapy, Rigshospitalet, Copenhagen Ø, Denmark.; Klemp K; Department of Ophthalmology, Rigshospitalet, Copenhagen Ø, Denmark.; Fledelius HC; Department of Ophthalmology, Rigshospitalet, Copenhagen Ø, Denmark.; Specht L; Department of Oncology, Section of Radiotherapy, Rigshospitalet, Copenhagen Ø, Denmark.; Kiilgaard JF; Department of Ophthalmology, Rigshospitalet, Copenhagen Ø, Denmark.
- Source
- Publisher: BMJ Pub. Group Country of Publication: England NLM ID: 0421041 Publication Model: Print-Electronic Cited Medium: Internet ISSN: 1468-2079 (Electronic) Linking ISSN: 00071161 NLM ISO Abbreviation: Br J Ophthalmol Subsets: MEDLINE
- Subject
- Language
- English
Background/aims: To present a new method to determine dose depth and the distance from the concave side of the plaque to the tumour base in patients with uveal melanoma treated with ruthenium-106 based on ultrasonic mirror image.
Methods: We used the mirror image associated with ultrasound during plaque brachytherapy to determine intraobserver reproducibility and interobserver agreement between two surgeons. 230 eyes with primary uveal melanoma were included in a retrospective analysis to determine the distance from the plaque to the tumour base using ultrasound. A phantom study was used to illustrate the effects on radiation dose to apex of the tumour when the dose depth was incorrectly determined. Doses to apex of the tumour were determined using Plaque Simulator.
Results: The intraobserver variation in dose depth measurement with plaque was significantly lower than for measures without plaque (p<0.001). Agreement between the surgeons was better with a plaque in place. Distances from the plaque to the tumour base were distributed with mean=0.99 (median: 1, range: 0.1-2.9 mm). From the phantom study, it was clear that the tumour did not receive the prescribed 100 Gy if the dose depth was incorrectly determined.
Conclusions: The dose depth in patients with uveal melanoma must be measured accurately for correct calculation of the radiation dose to the apex of the tumour. Repeated in vivo and in vitro ultrasound measurements of dose depth showed higher variance than measurements using the mirror image produced from a ruthenium plaque. Using the mirror image thus help to improve the dose calculation.
Competing Interests: Competing interests: None declared.
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