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Dosimetry of beta‐ray ophthalmic applicators: Comparison of different measurement methods
Author(s) -
Soares C. G.,
Vynckier S.,
Järvinen H.,
Cross W. G.,
Sipilä P.,
Flühs D.,
Schaeken B.,
Mourtada F. A.,
Bass G. A.,
Williams T. T.
Publication year - 2001
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.1376441
Subject(s) - dosimetry , medical physics , nuclear medicine , beta particle , optics , medical physicist , medicine , physics , nuclear physics
An international intercomparison of the dosimetry of three beta particle emitting ophthalmic applicators was performed, which involved measurements with radiochromic film, thermoluminescence dosimeters (TLDs), alanine pellets, plastic scintillators, extrapolation ionization chambers, a small fixed‐volume ionization chambers, a diode detector and a diamond detector. The sources studied were planar applicators of90 Sr – 90 Y and106 Ru – 106 Rh , and a concave applicator of106 Ru – 106 Rh . Comparisons were made of absolute dosimetry determined at 1 mm from the source surface in water or water‐equivalent plastic, and relative dosimetry along and perpendicular to the source axes. The results of the intercomparison indicate that the various methods yield consistent absolute dosimetry results at the level of 10%–14% (one standard deviation) depending on the source. For relative dosimetry along the source axis at depths of 5 mm or less, the agreement was 3%–9% (one standard deviation) depending on the source and the depth. Crucial to the proper interpretation of the measurement results is an accurate knowledge of the detector geometry, i.e., sensitive volume and amount of insensitive covering material. From the results of these measurements, functions which describe the relative dose rate along and perpendicular to the source axes are suggested.