TY - JOUR

T1 - Ultrasonic mirror image from ruthenium plaque facilitates calculation of uveal melanoma treatment dose

AU - Espensen, Charlotte Alfast

AU - Jensen, Peter Koch

AU - Fog, Lotte Stubkjær

AU - Appelt, Ane Lindegaard

AU - Klemp, Kristian

AU - Fledelius, Hans Callø

AU - Specht, Lena

AU - Kiilgaard, Jens Folke

PY - 2017/9

Y1 - 2017/9

N2 - 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.

AB - 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.

KW - Diagnostic tests/Investigation

KW - Imaging

KW - Neoplasia

KW - Sclera and Episclera

KW - Treatment other

U2 - 10.1136/bjophthalmol-2016-309626

DO - 10.1136/bjophthalmol-2016-309626

M3 - Journal article

C2 - 28159770

AN - SCOPUS:85013371928

VL - 101

SP - 1206

EP - 1210

JO - British Journal of Ophthalmology

JF - British Journal of Ophthalmology

SN - 0007-1161

IS - 9

ER -