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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-23 17:49 |
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Conference: Bucharest University Faculty of Physics 2014 Meeting
Section: Biophysics; Medical Physics
Title:
192Ir high-dose-rate brachytherapy for cervical cancer: evaluation on dosimetric impact of point A definition and specific radiobiological aspects
Authors:
Alina TĂNASE(1,3), M. DUMITRACHE(2,3)
Affiliation:
1) Emergency Central Military Hospital ”Dr. Carol Davila” Bucharest, Romania
2) Institute of Oncology ”Prof. Dr. Al. Trestioreanu”, Bucharest, Romania
3) Faculty of Physics, University of Bucharest, Romania
E-mail
alinatanasemail@yahoo.com
Keywords:
Cervical cancer, convetional HDR brachytherapy, A points, dose variation
Abstract:
According to the latest statistics, cervical cancer ranks second on the list of cancers that cause annually the most deaths in Romania, after breast cancer. The standard care for cervical cancer requires concomitant chemotherapy with external-beam radiotherapy (EBRT) and brachytherapy (BT). The BT treatment planning, even for high-dose-rate treatments (HDR), can be done using orthogonal radiographs and Manchester system in which the radiation dose is prescribed to point A: an estimate of where the uterine artery intersects with the ureter irrespective of an individual patient’s tumor characteristics.
The purpose of this work is to investigate the dosimetric impact of point A definitions for HDR BT plans and to underline some radiobiological considerations, in respect to the implication of EBRT–BT combination.
BT plans have been created for cervical cases with BrachyVision v.11 planning systems and two different point A definitions were explored: the revised Manchester point A and the new point A as recommended by the American Brachytherapy Society.
As a results, a small yet significant variations were found in point A locations (mean: 0.5 cm, maximum: 2.2 cm). The use of a new point A caused minimal dose variation. Conventional plans normalized to the new point A generated up to 11 % higher overall dose in terms of higher total reference air kerma than plans normalized to other points. Dosimetric changes due to point A definitions were up to 10 % on organs-at-risk.
For conventional plans, we concluded that the new point A definition leads to smaller variations caused during implant and/or differences in patient anatomy. Using the new point A is expected to produce more consistent brachytherapy plans and improve outcome analysis.
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