Liliana Martins1, Jose Guilherme Couto2, Barbara Barbosa3. 1. Radiotherapy Department - Escola Superior de Tecnologia da Saude do Porto, Rua Valente Perfeito, 322, 4400-330 Vila Nova de Gaia, Portugal. 2. Radiotherapy Department - Escola Superior de Tecnologia da Saude do Porto, Rua Valente Perfeito, 322, 4400-330 Vila Nova de Gaia, Portugal; Radiotherapy Department - Instituto Portugues de Oncologia do Porto, Rua Dr. António Bernardino de Almeida, 4200-072 Porto, Portugal; Radiography Department - Faculty of Health Sciences - University of Malta, Msida MSD 2080, Malta. 3. Radiotherapy Department - Instituto Portugues de Oncologia do Porto, Rua Dr. António Bernardino de Almeida, 4200-072 Porto, Portugal.
Abstract
AIM: The aim of this study is to evaluate differences in terms of the setup errors observed using kV planar image compared to CBCT for oesophageal cancer patients. BACKGROUND: Planar kV images are quick to acquire but only allow the observation of bony structures. CBCT allows the evaluation of soft tissues, which includes the oesophagus (and tumour) and OAR, giving a more accurate verification of the positioning. MATERIALS AND METHODS: All patients were imaged with both techniques between January 2012 and March 2014 were included in the study (16 patients, 212 kV images and 116 CBCT images). Differences between the setup errors observed on the two images modalities were studied. A correlation study between TNM staging, tumour location and immobilization systems with setup errors was also done. Finally, the calculation of systematic and random errors allowed to determine the CTV-PTV margin. RESULTS: A significant discrepancy (p < 0.05) between the setup errors observed with kV and CBCT was observed in the lateral direction. No statistical correlation was found between setup errors and tumour location, immobilization system or TNM staging. The CTV-PTV margin was smaller with CBCT in the vertical (0.6 cm vs. 0.9 cm) and longitudinal (0.7 cm vs. 1 cm) directions and smaller with kV for the lateral directions (0.8 cm vs. 0.9 cm). CONCLUSIONS: The chosen modality influences the setup error observed which will influence the correction applied. Allowing a better observation of the volumes of interest, CBCT should be the modality of choice in this pathology. The CTV-PTV margins could be shrunk if CBCT is used.
AIM: The aim of this study is to evaluate differences in terms of the setup errors observed using kV planar image compared to CBCT for oesophageal cancerpatients. BACKGROUND: Planar kV images are quick to acquire but only allow the observation of bony structures. CBCT allows the evaluation of soft tissues, which includes the oesophagus (and tumour) and OAR, giving a more accurate verification of the positioning. MATERIALS AND METHODS: All patients were imaged with both techniques between January 2012 and March 2014 were included in the study (16 patients, 212 kV images and 116 CBCT images). Differences between the setup errors observed on the two images modalities were studied. A correlation study between TNM staging, tumour location and immobilization systems with setup errors was also done. Finally, the calculation of systematic and random errors allowed to determine the CTV-PTV margin. RESULTS: A significant discrepancy (p < 0.05) between the setup errors observed with kV and CBCT was observed in the lateral direction. No statistical correlation was found between setup errors and tumour location, immobilization system or TNM staging. The CTV-PTV margin was smaller with CBCT in the vertical (0.6 cm vs. 0.9 cm) and longitudinal (0.7 cm vs. 1 cm) directions and smaller with kV for the lateral directions (0.8 cm vs. 0.9 cm). CONCLUSIONS: The chosen modality influences the setup error observed which will influence the correction applied. Allowing a better observation of the volumes of interest, CBCT should be the modality of choice in this pathology. The CTV-PTV margins could be shrunk if CBCT is used.
Authors: Padmanaban Sriram; S A Syamkumar; J Sam Deva Kumar; Sukumar Prabakar; Rajasekaran Dhanabalan; Nagarajan Vivekanandan Journal: Phys Med Date: 2011-11-10 Impact factor: 2.685
Authors: Maria A Hawkins; Alexandra Aitken; Vibeke N Hansen; Helen A McNair; Diana M Tait Journal: Radiother Oncol Date: 2010-12-06 Impact factor: 6.280
Authors: Jean-Pierre Bissonnette; Thomas G Purdie; Jane A Higgins; Winnie Li; Andrea Bezjak Journal: Int J Radiat Oncol Biol Phys Date: 2008-12-25 Impact factor: 7.038
Authors: Inga S Grills; Geoffrey Hugo; Larry L Kestin; Ana Paula Galerani; K Kenneth Chao; Jennifer Wloch; Di Yan Journal: Int J Radiat Oncol Biol Phys Date: 2007-10-29 Impact factor: 7.038
Authors: Heng Li; X Ronald Zhu; Lifei Zhang; Lei Dong; Sam Tung; Anesa Ahamad; K S Clifford Chao; William H Morrison; David I Rosenthal; David L Schwartz; Radhe Mohan; Adam S Garden Journal: Int J Radiat Oncol Biol Phys Date: 2008-04-18 Impact factor: 7.038