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161. A crowd-knowledge-based analysis of DVHs in SBRT: First steps towards a national virtual audit
Abstracts / Physica Medica 56 (2018) 133–278
163
Figure: Box plot of Dice and Hausdorff distance (HD) for rigid and deformable CT-MRI alignments.
https://doi.org/10.1016/j.ejmp.2018.04.170
160. Kilovoltage rotational radiotherapy of breast cancer with synchrotron radiation: A phantom study with 100 keV and 6 MV VMAT dose delivery M. Masi a, R. Castriconi b, F. Di Lillo a, A. Sarno a, G. Mettivier a, L. Perna b, M. Cattaneo b, C. Fiorino b, R. Calandrino b, P. Russo a a
Università di Napoli Federico II, Dipartimento di Fisica ‘‘Ettore Pancini”, Napoli, Italy b San Raffaele Scientific Institute, Milan, Italy Purpose. We proposed a new technique for breast cancer rotational radiotherapy using kilovoltage synchrotron radiation (SR) [1]. Here, we compared 2D dose distributions in a breast phantom at 6 MV in circular orbit Volumetric Arc Therapy (VMAT) with respect to 100 keV irradiation in rotational radiotherapy with SR. Methods. The dose distribution was evaluated with calibrated EBT3 radiochromic films inserted at midplane in a 14-cm diameter PMMA cylindrical phantom, simulating the pendant breast. We irradiated a cylindrical target (15 20 mm2 (W H)) at the centre of phantom. Measurements were performed at the Imaging and Medical Beamline (Australian Synchrotron, Clayton, Australia) at 100 keV, with a SR beam of size 15 20 mm2 (W H) continuously irradiat-
ing the phantom during a 360 deg rotation around the cylinder axis with a central dose to the target of 7 Gy. Megavoltage measurements were performed at 6 MV using a Varian Clinac iX System Linac, with a target dose of 6 Gy. Results. The principle of dose summation along the axis of rotation produced a dose distribution peaked at the centre of rotation for small fields. The target-to-surface dose ratio was 20:1 at 6 MV and 9:1 at 100 keV, for a target at the center of the phantom. Conclusions. We performed a feasibility test of kilovoltage rotational radiotherapy dedicated to the breast showing a target-tosurface dose ratio higher than with MV radiotherapy but still acceptable for skin tissue sparing. Reference 1. Di Lillo F. et al. Towards breast cancer rotational radiotherapy with synchrotron radiation. Phys Med 2017;41:20–5. https://doi.org/10.1016/j.ejmp.2018.04.171
161. A crowd-knowledge-based analysis of DVHs in SBRT: First steps towards a national virtual audit A. Savini, M. Fusella, M. Esposito, V. Ardu, G. Benecchi, A. Bergantin, G.R. Borzi, S. Bresciani, E. Cagni, C. Carbonini, M. Casati, S. Clemente, R. Consorti, S. Cora, E. DeMartin, R. ElGawhary, M.D. Falco, D. Fedele,
Figure 1: Concept of a virtual audit analysis feedback.
164
Abstracts / Physica Medica 56 (2018) 133–278
C. Fiandra, M.C. Frassanito, C. Garibaldi, G. Gasperi, F.R. Giglioli, G. Guidi, I. Ielo, V. Landoni, S. Magi, T. Malatesta, C. Marino, L. Masi, E. Moretti, S. Naccarato, B. Nardiello, R. Nigro, G. Pastore, M. Presello, V. Ravaglia, S. Russo, L. Strigari, S. Strolin, C. Talamonti, A. Vaiano, S. Vigorito, E. Villaggi, M. Stasi, P. Mancosu SBRT Working Group, AIFM – Italian Association of Medical Physics, Italy Purpose. Currently, most of the multicenter analyses on treatment planning rely on the extraction of selected data from the DVH of each plan. A grouped analysis can be biased due to different algorithms implemented in different TPSs used to generate the DVH. In this work we used a consistent method to present a preliminary analysis of multiple data coming from a national survey on stereotactic body radiotherapy (SBRT) planning. Methods. A single spine case was shared among 36 radiation oncology centers. The dose prescription was 30 Gy in 3 fractions with specific constraints on target coverage and dose to nearby organs at risk. Data were collected in DICOM-RT format. A script was developed in R language using the RadOnc R-Package for recalculating the DVHs using the same algorithm. Specific DVH points (V30Gy, D90%, D2%) collected from the centers were compared with those recalculated with RadOnc. A grouped analysis of recalculated DVHs was performed therefore eliminating the bias due to different DVH calculation algorithms. Results. Differences between collected and recalculated DVHs were minimal, however in some cases deviations up to 1.5% were observed. The multiple-DVH analysis showed a notable variability on target dose level (Fig. 1), up to 150% likely related to constraints on target coverage and SBRT technique. This variability was caused mainly by different planning optimization strategies, rather than by the use of a specific treatment technology. Conclusions. The observed variability suggests that comparable standards in patient treatment among different centers can be obtained if a consistent high-level data sharing capability is granted. In the strive to harmonize the planning process, this analysis constitutes a first step toward the creation of a platform of crowdknowledge-based planning guidelines. This platform could represent a high-quality benchmark for those centers that are willing to implement SBRT techniques (concept expressed in Fig. 1).
Results. 98.45% of plans was characterized by a gamma passing rates above 90%, while only 14 plans yielded values under the acceptance threshold. CL resulted to be more restrictive: 95,34% of plans satisfied the passing criteria, while 42 plans presented CL > 1. Nevertheless, gamma passing rates and CL showed a strong correlation (Pearson absolute value above 0.93). Plan complexity parameters underlined a moderate correlation with gamma passing rates, with an absolute value between 0.39 and 0.47. More deeply, a negative correlation was observed with LT, while MCS and LTMCS presented a positive correlation. CL showed similar results characterized by an absolute Pearson factor between 0.47 and 0.51. Results of Pearson analyses are summarized in Table 1. Pearson Coefficient
LT LTi MCSv LTMCS
Gamma passing rate
CL
0.47 ( 0.42– 0.52) 0.44 ( 0.38– 0.48) 0.39 (0.34–0.45) 0.44 (0.39–0.49)
0.51 (0.46–0.55) 0.47 (0.42–0.52) 0.47 ( 0.42– 0.52) 0.51 ( 0.46– 0.55)
Conclusions. Local gamma analysis results underlined a significant correlation with plan complexity parameters, with larger correlations obtained with CL. References 1. Venselaar J, Welleweerd H, Mijnheer B. Tolerances for the accuracy of photon beam dose calculations of treatment planning systems. Radiother Oncol 2001;60(2):191–201. 2. McNiven AL, Sharpe MB, Purdie TG. A new metric for assessing IMRT modulation complexity and plan deliverability. Med Phys 2010;37(2):505–15. 3. Masi L, Doro R, Favuzza V, Cipressi S, Livi L. Impact of plan parameters on the dosimetric accuracy of volumetric arc therapy. Med Phys 2013;40(7):071718. https://doi.org/10.1016/j.ejmp.2018.04.173
https://doi.org/10.1016/j.ejmp.2018.04.172
162. A study on the correlation between plan parameters and gamma index analysis of Volumetric Modulated Arc Therapy D Panizza a, R Villa a,b, G Montanari a, V Tremolada a, A Crespi a
163. Field-in-Field versus 3D standard techniques for breast cancer: Dosimetric and reproducibility study P. D’Avenia a, R. Nigro b, M. Camarda a, E. Di Nicola a, M. Giannini c, M.G. Mangiacotti b, F. Mascioni c, L. Montani a, S. Riccardi b, G. Rossi a, S. Fattori a a
Macerata Hospital, UOSD Medical Physics, Macerata, Italy San Camillo De Lellis Hospital, UOC Radiotherapy, Rieti, Italy c Macerata Hospital, UOC Radiotherapy, Macerata, Italy
a
ASST Monza, Medical Physics Department, Monza, Italy b University of Milan, Medical Physics Specialization School, Milan, Italy
b
Purpose. To evaluate the effect of plan complexity parameters in patient-specific quality assurance (QA). Methods. Evaluation of 902 clinical VMAT plans, optimized using a 3° control point separation, was achieved by local gamma index analysis (3%, 3 mm) between delivered and calculated dose. Confidence limit (CL) for 93.5% interval (p = 0.065) was evaluated too [1]. All plans were delivered by a 6MV Linac to a biplanar diode array for patient-specific QA. Plan complexity was investigated throughout different parameters: average leaf travel (LT), average in-field leaf travel (LTi) [2], modulation complexity score applied to VMAT (MCSv) and a multiplicative combination of them (LTMCS) [3]. Pearson’s correlation analysis was performed between gamma passing rates, CL and each parameter.
Purpose. Field-in-Field (FIF) is an advanced radiation therapy planning technique [1]. We studied the effectiveness of this technique for breast radiotherapy, with respect to 3D standard technique, in terms of dosimetric benefits and treatment reproducibility. PTV volume dependence on both techniques was also investigated. Methods. Two endpoints were analysed. For the first endpoint, dosimetric benefits were studied on 230 breast cancer patients from Macerata hospital who received whole breast radiotherapy with either 3D standard or FIF technique. The second endpoint was a reproducibility study: 28 patients from Macerata and Rieti hospitals were included. For each patient, a 3D standard plan and a FIF plan were prepared on the first simulation CT. All patients underwent other two CT scans on which the original plans were recalculated.
163
Figure: Box plot of Dice and Hausdorff distance (HD) for rigid and deformable CT-MRI alignments.
https://doi.org/10.1016/j.ejmp.2018.04.170
160. Kilovoltage rotational radiotherapy of breast cancer with synchrotron radiation: A phantom study with 100 keV and 6 MV VMAT dose delivery M. Masi a, R. Castriconi b, F. Di Lillo a, A. Sarno a, G. Mettivier a, L. Perna b, M. Cattaneo b, C. Fiorino b, R. Calandrino b, P. Russo a a
Università di Napoli Federico II, Dipartimento di Fisica ‘‘Ettore Pancini”, Napoli, Italy b San Raffaele Scientific Institute, Milan, Italy Purpose. We proposed a new technique for breast cancer rotational radiotherapy using kilovoltage synchrotron radiation (SR) [1]. Here, we compared 2D dose distributions in a breast phantom at 6 MV in circular orbit Volumetric Arc Therapy (VMAT) with respect to 100 keV irradiation in rotational radiotherapy with SR. Methods. The dose distribution was evaluated with calibrated EBT3 radiochromic films inserted at midplane in a 14-cm diameter PMMA cylindrical phantom, simulating the pendant breast. We irradiated a cylindrical target (15 20 mm2 (W H)) at the centre of phantom. Measurements were performed at the Imaging and Medical Beamline (Australian Synchrotron, Clayton, Australia) at 100 keV, with a SR beam of size 15 20 mm2 (W H) continuously irradiat-
ing the phantom during a 360 deg rotation around the cylinder axis with a central dose to the target of 7 Gy. Megavoltage measurements were performed at 6 MV using a Varian Clinac iX System Linac, with a target dose of 6 Gy. Results. The principle of dose summation along the axis of rotation produced a dose distribution peaked at the centre of rotation for small fields. The target-to-surface dose ratio was 20:1 at 6 MV and 9:1 at 100 keV, for a target at the center of the phantom. Conclusions. We performed a feasibility test of kilovoltage rotational radiotherapy dedicated to the breast showing a target-tosurface dose ratio higher than with MV radiotherapy but still acceptable for skin tissue sparing. Reference 1. Di Lillo F. et al. Towards breast cancer rotational radiotherapy with synchrotron radiation. Phys Med 2017;41:20–5. https://doi.org/10.1016/j.ejmp.2018.04.171
161. A crowd-knowledge-based analysis of DVHs in SBRT: First steps towards a national virtual audit A. Savini, M. Fusella, M. Esposito, V. Ardu, G. Benecchi, A. Bergantin, G.R. Borzi, S. Bresciani, E. Cagni, C. Carbonini, M. Casati, S. Clemente, R. Consorti, S. Cora, E. DeMartin, R. ElGawhary, M.D. Falco, D. Fedele,
Figure 1: Concept of a virtual audit analysis feedback.
164
Abstracts / Physica Medica 56 (2018) 133–278
C. Fiandra, M.C. Frassanito, C. Garibaldi, G. Gasperi, F.R. Giglioli, G. Guidi, I. Ielo, V. Landoni, S. Magi, T. Malatesta, C. Marino, L. Masi, E. Moretti, S. Naccarato, B. Nardiello, R. Nigro, G. Pastore, M. Presello, V. Ravaglia, S. Russo, L. Strigari, S. Strolin, C. Talamonti, A. Vaiano, S. Vigorito, E. Villaggi, M. Stasi, P. Mancosu SBRT Working Group, AIFM – Italian Association of Medical Physics, Italy Purpose. Currently, most of the multicenter analyses on treatment planning rely on the extraction of selected data from the DVH of each plan. A grouped analysis can be biased due to different algorithms implemented in different TPSs used to generate the DVH. In this work we used a consistent method to present a preliminary analysis of multiple data coming from a national survey on stereotactic body radiotherapy (SBRT) planning. Methods. A single spine case was shared among 36 radiation oncology centers. The dose prescription was 30 Gy in 3 fractions with specific constraints on target coverage and dose to nearby organs at risk. Data were collected in DICOM-RT format. A script was developed in R language using the RadOnc R-Package for recalculating the DVHs using the same algorithm. Specific DVH points (V30Gy, D90%, D2%) collected from the centers were compared with those recalculated with RadOnc. A grouped analysis of recalculated DVHs was performed therefore eliminating the bias due to different DVH calculation algorithms. Results. Differences between collected and recalculated DVHs were minimal, however in some cases deviations up to 1.5% were observed. The multiple-DVH analysis showed a notable variability on target dose level (Fig. 1), up to 150% likely related to constraints on target coverage and SBRT technique. This variability was caused mainly by different planning optimization strategies, rather than by the use of a specific treatment technology. Conclusions. The observed variability suggests that comparable standards in patient treatment among different centers can be obtained if a consistent high-level data sharing capability is granted. In the strive to harmonize the planning process, this analysis constitutes a first step toward the creation of a platform of crowdknowledge-based planning guidelines. This platform could represent a high-quality benchmark for those centers that are willing to implement SBRT techniques (concept expressed in Fig. 1).
Results. 98.45% of plans was characterized by a gamma passing rates above 90%, while only 14 plans yielded values under the acceptance threshold. CL resulted to be more restrictive: 95,34% of plans satisfied the passing criteria, while 42 plans presented CL > 1. Nevertheless, gamma passing rates and CL showed a strong correlation (Pearson absolute value above 0.93). Plan complexity parameters underlined a moderate correlation with gamma passing rates, with an absolute value between 0.39 and 0.47. More deeply, a negative correlation was observed with LT, while MCS and LTMCS presented a positive correlation. CL showed similar results characterized by an absolute Pearson factor between 0.47 and 0.51. Results of Pearson analyses are summarized in Table 1. Pearson Coefficient
LT LTi MCSv LTMCS
Gamma passing rate
CL
0.47 ( 0.42– 0.52) 0.44 ( 0.38– 0.48) 0.39 (0.34–0.45) 0.44 (0.39–0.49)
0.51 (0.46–0.55) 0.47 (0.42–0.52) 0.47 ( 0.42– 0.52) 0.51 ( 0.46– 0.55)
Conclusions. Local gamma analysis results underlined a significant correlation with plan complexity parameters, with larger correlations obtained with CL. References 1. Venselaar J, Welleweerd H, Mijnheer B. Tolerances for the accuracy of photon beam dose calculations of treatment planning systems. Radiother Oncol 2001;60(2):191–201. 2. McNiven AL, Sharpe MB, Purdie TG. A new metric for assessing IMRT modulation complexity and plan deliverability. Med Phys 2010;37(2):505–15. 3. Masi L, Doro R, Favuzza V, Cipressi S, Livi L. Impact of plan parameters on the dosimetric accuracy of volumetric arc therapy. Med Phys 2013;40(7):071718. https://doi.org/10.1016/j.ejmp.2018.04.173
https://doi.org/10.1016/j.ejmp.2018.04.172
162. A study on the correlation between plan parameters and gamma index analysis of Volumetric Modulated Arc Therapy D Panizza a, R Villa a,b, G Montanari a, V Tremolada a, A Crespi a
163. Field-in-Field versus 3D standard techniques for breast cancer: Dosimetric and reproducibility study P. D’Avenia a, R. Nigro b, M. Camarda a, E. Di Nicola a, M. Giannini c, M.G. Mangiacotti b, F. Mascioni c, L. Montani a, S. Riccardi b, G. Rossi a, S. Fattori a a
Macerata Hospital, UOSD Medical Physics, Macerata, Italy San Camillo De Lellis Hospital, UOC Radiotherapy, Rieti, Italy c Macerata Hospital, UOC Radiotherapy, Macerata, Italy
a
ASST Monza, Medical Physics Department, Monza, Italy b University of Milan, Medical Physics Specialization School, Milan, Italy
b
Purpose. To evaluate the effect of plan complexity parameters in patient-specific quality assurance (QA). Methods. Evaluation of 902 clinical VMAT plans, optimized using a 3° control point separation, was achieved by local gamma index analysis (3%, 3 mm) between delivered and calculated dose. Confidence limit (CL) for 93.5% interval (p = 0.065) was evaluated too [1]. All plans were delivered by a 6MV Linac to a biplanar diode array for patient-specific QA. Plan complexity was investigated throughout different parameters: average leaf travel (LT), average in-field leaf travel (LTi) [2], modulation complexity score applied to VMAT (MCSv) and a multiplicative combination of them (LTMCS) [3]. Pearson’s correlation analysis was performed between gamma passing rates, CL and each parameter.
Purpose. Field-in-Field (FIF) is an advanced radiation therapy planning technique [1]. We studied the effectiveness of this technique for breast radiotherapy, with respect to 3D standard technique, in terms of dosimetric benefits and treatment reproducibility. PTV volume dependence on both techniques was also investigated. Methods. Two endpoints were analysed. For the first endpoint, dosimetric benefits were studied on 230 breast cancer patients from Macerata hospital who received whole breast radiotherapy with either 3D standard or FIF technique. The second endpoint was a reproducibility study: 28 patients from Macerata and Rieti hospitals were included. For each patient, a 3D standard plan and a FIF plan were prepared on the first simulation CT. All patients underwent other two CT scans on which the original plans were recalculated.