Ultrasonic mirror image from ruthenium plaque facilitates calculation of uveal melanoma treatment dose.
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.



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.



The intraobserver variation in dose depth measurementwithplaque was significantly lower than for measureswithoutplaque (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.



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.
Department of Oncology, Section of Radiotherapy, Rigshospitalet, Copenhagen Ø, Denmark.|Department of Ophthalmology, Rigshospitalet, Copenhagen Ø, Denmark.
Charlotte Alfast
CA
Espensen
Department of Ophthalmology, Roskilde Hospital, Roskilde, Denmark.
Peter Koch
PK
Jensen
Department of Oncology, Section of Radiotherapy, Rigshospitalet, Copenhagen Ø, Denmark.
Lotte Stubkjær
LS
Fog
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.
Ane Lindegaard
AL
Appelt
Department of Ophthalmology, Rigshospitalet, Copenhagen Ø, Denmark.
Kristian
K
Klemp
Department of Ophthalmology, Rigshospitalet, Copenhagen Ø, Denmark.
Hans Callø
HC
Fledelius
Department of Oncology, Section of Radiotherapy, Rigshospitalet, Copenhagen Ø, Denmark.
Lena
L
Specht
Department of Ophthalmology, Rigshospitalet, Copenhagen Ø, Denmark.
Jens Folke
0000-0003-1054-1460
JF
Kiilgaard
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001918:Brachytherapy; D005260:Female; D006801:Humans; D008297:Male; D008545:Melanoma / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D008875:Middle Aged; D015588:Observer Variation; D019047:Phantoms, Imaging; D011874:Radiometry / Q000379:methods*; D011879:Radiotherapy Dosage; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012429:Ruthenium Radioisotopes / Q000627:therapeutic use*; D014463:Ultrasonography; D014604:Uveal Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D055815:Young Adult; D000098943:Uveal Melanoma
D012429:Ruthenium Radioisotopes
Diagnostic tests/Investigation; Imaging; Neoplasia; Sclera and Episclera; Treatment other