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12. Clinical evaluation of a transmission detector system and comparison with a homogeneous 3D phantom dosimeter
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Abstracts / Physica Medica 56 (2018) 59–132
delivery QA even employing filmless solutions. A 2%2 mm criteria is not always tight enough. References 1. Blank O, Masi L, Chan MKH, Poppe B. High resolution ion chamber array delivery quality assurance for robotic radiosurgery: commissioning and validation. EJMP 2016;32:838–46. https://doi.org/10.1016/j.ejmp.2018.04.021
12. Clinical evaluation of a transmission detector system and comparison with a homogeneous 3D phantom dosimeter F.R. Giglioli a, E. Gallio a, P. Franco b, S. Badellino b, U. Ricardi b, C. Fiandra b a
A.O.U. Città della Salute e della Scienza, Medical Physics Unit, Turin, Italy b University of Torino, Radiation Oncology Department, Turin, Italy Purpose. To evaluate the clinical performance of a novel detector based on transmission measurements. Methods. Fifty patients were included in the study. The treatment plans were generated by two different Treatment Planning Systems (TPS). All treatment plans were verified by the Dolphin and the Delta4 in the same session and then by the Delta4 alone. The attenuation factor was evaluated for each patient by comparing Delta4 measurements with and without Dolphin. Gamma evaluation was performed with both systems in order to compare the plan dose with the irradiated dose. Parameters of dose-volume based indices for PTV (Gamma index 2%-2 mm) and OARs doses (Dmax and dose at the threshold volume) were considered for Compass calculation and Dolphin reconstruction. Clinical decisions were made by two physicians in order to evaluate the ‘‘pass”, ‘‘fail” or ‘‘evaluate” grade
Table 1 Clinical evaluation results in terms of ”pass”, ”evaluate” or ”fail” for Dolphin. Site
Pass
Evaluate
Fail
Fail or Evaluate reason
H&N
5
5
0
Dose to parothids PTV overdose Oral cavity dose
Lung SNC
10 7
3
0 0
Lung SBRT Rectum
8 10
2
0 0
Lens doses PTV underdosage Dose to trachea
of the treatment plans. A statistical analysis was performed in order to find correlation among dose parameters and clinical evaluation. Results. A value of 10.7 ± 0.7 was found for detector attenuation. Both detectors showed high reproducibility and correlation between the 2 mm leaf errors and gamma metric, with Dolphin using 2%-2 mm and Delta4 only using 1%-1 mm. No patients were classified as ‘‘fail” by the two instruments as well as by physicians (Table 1); while no correlation was found between the Delta4 gamma metric and physician classification, a significant correlation was observed for Dolphin (Fig. 1). Conclusions. Our data have shown a correlation between clinical decision and PTV gamma metric in the PTV area for Dolphin system while no correlation was observed with Delta4 measurements; therefore the PTV number of points with gamma P1 (2%-2 mm) seems to predict the consistency of the irradiated dose to the patient. https://doi.org/10.1016/j.ejmp.2018.04.022
13. Epid-based in vivo dosimetry for lung SBRT delivered with multiple breath-hold segmented VMAT S. Cilla a, A. Ianiro a, M. Craus a, P. Viola a, G. Macchia b, A.G. Morganti c, V. Valentini b,d, F. Deodato b a Medical Physics Unit, Foundation for Research and Cure ‘‘John Paul II”, Campobasso, Italy b Radiation Oncology Unit, Foundation for Research and Cure ‘‘John Paul II”, Campobasso, Italy c Radiation Oncology Department, DIMES, S. Orsola-Malpighi Hospital, University of Bologna, Bologna, Italy d Radiation Oncology Department, Foundation University Hospital ‘‘A. Gemelli”, Catholic University of Sacred Heart, Roma, Italy
Purpose . We evaluated an EPID-based IVD method for the dose verification and the treatment reproducibility of SBRT-VMAT treatments in clinical routine. Methods. 10 patients with lung metastases treated with Elekta VMAT technique were enrolled. All patients were irradiated in 5 consecutive fractions, with total doses of 50 Gy. Set-up was carried out with the Elekta stereotactic body frame. Eight patients were simulated and treated using the Active Breath Coordinator (ABC) system, a spirometer enabling patients to maintain a breath-hold at a predetermined lung volume. Two patients were simulated and treated in free-breathing using an abdominal compressor. IVD was performed using the SOFTDISO software (Best Medical Italy). IVD tests were evaluated by means of (i) ratio R between daily in vivo isocenter dose and planned dose and (ii) c-analysis between EPID integral portal images in terms of percentage of points with c-value smaller than
Figure 1- Correlation between the clinical evaluation and the results obtained for the Dolphin (a) and Delta4(b)
Abstracts / Physica Medica 56 (2018) 59–132
delivery QA even employing filmless solutions. A 2%2 mm criteria is not always tight enough. References 1. Blank O, Masi L, Chan MKH, Poppe B. High resolution ion chamber array delivery quality assurance for robotic radiosurgery: commissioning and validation. EJMP 2016;32:838–46. https://doi.org/10.1016/j.ejmp.2018.04.021
12. Clinical evaluation of a transmission detector system and comparison with a homogeneous 3D phantom dosimeter F.R. Giglioli a, E. Gallio a, P. Franco b, S. Badellino b, U. Ricardi b, C. Fiandra b a
A.O.U. Città della Salute e della Scienza, Medical Physics Unit, Turin, Italy b University of Torino, Radiation Oncology Department, Turin, Italy Purpose. To evaluate the clinical performance of a novel detector based on transmission measurements. Methods. Fifty patients were included in the study. The treatment plans were generated by two different Treatment Planning Systems (TPS). All treatment plans were verified by the Dolphin and the Delta4 in the same session and then by the Delta4 alone. The attenuation factor was evaluated for each patient by comparing Delta4 measurements with and without Dolphin. Gamma evaluation was performed with both systems in order to compare the plan dose with the irradiated dose. Parameters of dose-volume based indices for PTV (Gamma index 2%-2 mm) and OARs doses (Dmax and dose at the threshold volume) were considered for Compass calculation and Dolphin reconstruction. Clinical decisions were made by two physicians in order to evaluate the ‘‘pass”, ‘‘fail” or ‘‘evaluate” grade
Table 1 Clinical evaluation results in terms of ”pass”, ”evaluate” or ”fail” for Dolphin. Site
Pass
Evaluate
Fail
Fail or Evaluate reason
H&N
5
5
0
Dose to parothids PTV overdose Oral cavity dose
Lung SNC
10 7
3
0 0
Lung SBRT Rectum
8 10
2
0 0
Lens doses PTV underdosage Dose to trachea
of the treatment plans. A statistical analysis was performed in order to find correlation among dose parameters and clinical evaluation. Results. A value of 10.7 ± 0.7 was found for detector attenuation. Both detectors showed high reproducibility and correlation between the 2 mm leaf errors and gamma metric, with Dolphin using 2%-2 mm and Delta4 only using 1%-1 mm. No patients were classified as ‘‘fail” by the two instruments as well as by physicians (Table 1); while no correlation was found between the Delta4 gamma metric and physician classification, a significant correlation was observed for Dolphin (Fig. 1). Conclusions. Our data have shown a correlation between clinical decision and PTV gamma metric in the PTV area for Dolphin system while no correlation was observed with Delta4 measurements; therefore the PTV number of points with gamma P1 (2%-2 mm) seems to predict the consistency of the irradiated dose to the patient. https://doi.org/10.1016/j.ejmp.2018.04.022
13. Epid-based in vivo dosimetry for lung SBRT delivered with multiple breath-hold segmented VMAT S. Cilla a, A. Ianiro a, M. Craus a, P. Viola a, G. Macchia b, A.G. Morganti c, V. Valentini b,d, F. Deodato b a Medical Physics Unit, Foundation for Research and Cure ‘‘John Paul II”, Campobasso, Italy b Radiation Oncology Unit, Foundation for Research and Cure ‘‘John Paul II”, Campobasso, Italy c Radiation Oncology Department, DIMES, S. Orsola-Malpighi Hospital, University of Bologna, Bologna, Italy d Radiation Oncology Department, Foundation University Hospital ‘‘A. Gemelli”, Catholic University of Sacred Heart, Roma, Italy
Purpose . We evaluated an EPID-based IVD method for the dose verification and the treatment reproducibility of SBRT-VMAT treatments in clinical routine. Methods. 10 patients with lung metastases treated with Elekta VMAT technique were enrolled. All patients were irradiated in 5 consecutive fractions, with total doses of 50 Gy. Set-up was carried out with the Elekta stereotactic body frame. Eight patients were simulated and treated using the Active Breath Coordinator (ABC) system, a spirometer enabling patients to maintain a breath-hold at a predetermined lung volume. Two patients were simulated and treated in free-breathing using an abdominal compressor. IVD was performed using the SOFTDISO software (Best Medical Italy). IVD tests were evaluated by means of (i) ratio R between daily in vivo isocenter dose and planned dose and (ii) c-analysis between EPID integral portal images in terms of percentage of points with c-value smaller than
Figure 1- Correlation between the clinical evaluation and the results obtained for the Dolphin (a) and Delta4(b)