Radiobiological and physical effects of patient setup errors during whole breast irradiation
International Journal of Radiation Research. 2017; 15 (4): 343-352
em En
| IMEMR
| ID: emr-197063
Biblioteca responsável:
EMRO
Background: The dose-related effects of patient setup errors on bio-physical indices were evaluated for the conventional wedge [CW] and field-in-field [FIF] whole breast irradiation techniques [WBI]
Materials and Methods: The treatment plans of 10 patients receiving left WBI were retrospectively selected for evaluation. The bio-physical effects of dose variations were evaluated by shifting the isocenters and gantry-angles of the treatment plans. Dose-volume histograms of the planning target volume [PTV], heart, and lungs were generated, and the conformity index [Cl], homogeneity index [HI], tumor control probability [TCP], and normal tissue complication probability [NTCP] were determined
Results: The D95 of the PTV for an [isocenter shift plan] with a posterior direction decreased by approximately 15%, and the TCP of the PTV decreased by approximately 50% for the FIF technique and by 40% for the CW; however, the NTCPs of the lungs and heart increased for both techniques. Increasing the gantry-angle decreased the TCPs of the PTV by 24.4% [CW] and by 34% [FIF]. The NTCPs of the lungs and heart for the two techniques differed by only 3%. The CIs and His for the CW case were higher than the corresponding values obtained for the FIF case. Significant differences were observed between the two techniques [p<0.01]
Conclusion: Our results revealed that the biophysical properties of the FIF case were more sensitive to setup errors than those in the CW case. The radiobiological-based analysis could be detected significant dosimetric errors and provided a practical patient quality assurance method for guiding the bio-physical effects?
Materials and Methods: The treatment plans of 10 patients receiving left WBI were retrospectively selected for evaluation. The bio-physical effects of dose variations were evaluated by shifting the isocenters and gantry-angles of the treatment plans. Dose-volume histograms of the planning target volume [PTV], heart, and lungs were generated, and the conformity index [Cl], homogeneity index [HI], tumor control probability [TCP], and normal tissue complication probability [NTCP] were determined
Results: The D95 of the PTV for an [isocenter shift plan] with a posterior direction decreased by approximately 15%, and the TCP of the PTV decreased by approximately 50% for the FIF technique and by 40% for the CW; however, the NTCPs of the lungs and heart increased for both techniques. Increasing the gantry-angle decreased the TCPs of the PTV by 24.4% [CW] and by 34% [FIF]. The NTCPs of the lungs and heart for the two techniques differed by only 3%. The CIs and His for the CW case were higher than the corresponding values obtained for the FIF case. Significant differences were observed between the two techniques [p<0.01]
Conclusion: Our results revealed that the biophysical properties of the FIF case were more sensitive to setup errors than those in the CW case. The radiobiological-based analysis could be detected significant dosimetric errors and provided a practical patient quality assurance method for guiding the bio-physical effects?
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Índice:
IMEMR
Idioma:
En
Revista:
Int. J. Radiat. Res.
Ano de publicação:
2017