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Please use this identifier to cite or link to this item: http://hdl.handle.net/1942/18706

Title: HDR Ir-192 source speed measurements using a high speed video camera
Authors: Fonseca, Gabriel P.
Viana, Rodrigo S. S.
Podesta, Mark
Rubo, Rodrigo A.
de Sales, Camila P.
RENIERS, Brigitte
Yoriyaz, Helio
Verhaegen, Frank
Issue Date: 2015
Citation: MEDICAL PHYSICS, 42 (1), p. 412-415
Abstract: Purpose: The dose delivered with a HDR Ir-192 afterloader can be separated into a dwell component, and a transit component resulting from the source movement. The transit component is directly dependent on the source speed profile and it is the goal of this study to measure accurate source speed profiles. Methods: A high speed video camera was used to record the movement of a Ir-192 source (Nucletron, an Elekta company, Stockholm, Sweden) for interdwell distances of 0.25-5 cm with dwell times of 0.1, 1, and 2 s. Transit dose distributions were calculated using a Monte Carlo code simulating the source movement. Results: The source stops at each dwell position oscillating around the desired position for a duration up to (0.026 +/- 0.005) s. The source speed profile shows variations between 0 and 81 cm/s with average speed of similar to 33 cm/s for most of the interdwell distances. The source stops for up to (0.005 +/- 0.001) s at nonprogrammed positions in between two programmed dwell positions. The dwell time correction applied by the manufacturer compensates the transit dose between the dwell positions leading to a maximum overdose of 41 mGy for the considered cases and assuming an air-kerma strength of 48 000 U. The transit dose component is not uniformly distributed leading to over and underdoses, which is within 1.4% for commonly prescribed doses (3-10 Gy). Conclusions: The source maintains its speed even for the short interdwell distances. Dose variations due to the transit dose component are much lower than the prescribed treatment doses for brachytherapy, although transit dose component should be evaluated individually for clinical cases. (c) 2015 American Association of Physicists in Medicine.
Notes: Verhaegen, F (reprint author) [Fonseca, Gabriel P.; Viana, Rodrigo S. S.; Yoriyaz, Helio] CNEN SP, IPEN, BR-05508000 Sao Paulo, Brazil. [Fonseca, Gabriel P.; Podesta, Mark; Reniers, Brigitte; Verhaegen, Frank] Maastricht Univ, Med Ctr, GROW Sch Oncol & Dev Biol, Dept Radiat Oncol MAASTRO, NL-6201 BN Maastricht, Netherlands. [Rubo, Rodrigo A.; de Sales, Camila P.] Univ Sao Paulo HC FMUSP, Hosp Clin, BR-05508000 Sao Paulo, Brazil. [Reniers, Brigitte] Hasselt Univ, CMK, Res Grp NuTeC, B-3590 Diepenbeek, Belgium. [Verhaegen, Frank] McGill Univ, Dept Oncol, Med Phys Unit, Montreal, PQ H3G 1A4, Canada. frank.verhaegen@maastro.nl
URI: http://hdl.handle.net/1942/18706
DOI: 10.1118/1.4903286
ISI #: 000347957200040
ISSN: 0094-2405
Category: A1
Type: Journal Contribution
Validation: ecoom, 2016
Appears in Collections: Research publications

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