Measurement of the influence of titanium hip prosthesis on therapeutic electron beam dose distributions in a novel pelvic phantom |
| |
| Affiliation: | 1. Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, Spain;2. Servicio de Radiofísica, Hospital Universitario Virgen Macarena, Sevilla, Spain;3. Instituto de Física, Pontificia Universidad Católica de Chile, Santiago de Chile, Chile;4. Istituto Nazionale di Fisica Nucleare, Frascati, Italy;2. Department of Radiation Oncology, University of California, Davis, CA;1. Graduate School of Medical Sciences, Kyushu University, 3-1-1, Maidashi, Higashi-ku, Fukuoka 812-8582, Japan;2. Faculty of Medical Sciences, Kyushu University, 3-1-1, Maidashi, Higashi-ku, Fukuoka 812-8582, Japan;3. Department of Health Sciences, School of Medicine, Kyushu University, 3-1-1, Maidashi, Higashi-ku, Fukuoka 812-8582, Japan;4. Department of Medical Technology, Kyushu University Hospital, 3-1-1, Maidashi, Higashi-ku, Fukuoka 812-8582, Japan;5. Saga Heavy Ion Medical Accelerator in Tosu, 415, Harakoga-cho, Tosu 841-0071, Japan;1. Department of Medical Physics, Centre Oscar Lambret and University Lille 1, France;2. Academic Department of Radiation Oncology, Centre Oscar Lambret and University Lille 2, France;1. CELIA, Centre Laser Intenses et Applications, Université de Bordeaux-CNRS-CEA, F-33400 Talence, France;2. Department of Radiotherapy, Institut Bergonié, Comprehensive Cancer Center, F-33076 Bordeaux, France |
| |
| Abstract: | PurposeTo investigate the degree of 18 and 22 MeV electron beam dose perturbations caused by unilateral hip titanium (Ti) prosthesis.MethodsMeasurements were acquired using Gafchromic EBT2 film in a novel pelvic phantom made out of Nylon-12 slices in which a Ti-prosthesis is embedded. Dose perturbations were measured and compared using depth doses for 8 × 8, 10 × 10 and 11 × 11 cm2 applicator-defined field sizes at 95 cm source-surface-distance (SSD). Comparisons were also made between film data at 100 cm SSD for a 10 × 10 cm2 field and dose calculations made on CMS XiO treatment planning system utilizing the pencil beam algorithm. The extent of dose deviations caused by the Ti prosthesis based on film data was quantified through the dose enhancement factor (DEF), defined as the ratio of the dose influenced by the prosthesis and the unchanged beam.ResultsAt the interface between Nylon-12 and the Ti implant on the prosthesis entrance side, the dose increased to values of 21 ± 1% and 23 ± 1% for 18 and 22 MeV electron beams, respectively. DEFs increased with increasing electron energy and field size, and were found to fall off quickly with distance from the nylon-prosthesis interface. A comparison of film and XiO depth dose data for 18 and 22 MeV gave relative errors of 20% and 25%, respectively.ConclusionThis study outlines the lack of accuracy of the XiO TPS for electron planning in highly heterogeneous media. So a dosimetric error of 20–25% could influence clinical outcome. |
| |
| Keywords: | Titanium prosthesis Nylon-12 phantom Electrons Dose perturbations |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
