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225. Low modulated 6 MV Flattening Filter Free Intensity Modulated Radiation Therapy (FFF-IMRT) for left breast treatments with Active Breath Coordinator™ (ABC): A feasibility study
Abstracts / Physica Medica 56 (2018) 133–278
225. Low modulated 6 MV Flattening Filter Free Intensity Modulated Radiation Therapy (FFF-IMRT) for left breast treatments with Active Breath CoordinatorTM (ABC): A feasibility study P.A. De Lucia a,b, M. Chieregato b, M. Galelli b, S. Ren Kaiser b, C. Bassetti b, L. Donadoni c, A. Huscher c, I.S. Villa c, M. Bignardi c a Scuola di Specializzazione in Fisica Medica, Università degli studi di Milano, Milano, Italy b Fondazione Poliambulanza Istituto Ospedaliero, Fisica Sanitaria, Brescia, Italy c Fondazione Poliambulanza Istituto Ospedaliero, Radioterapia, Brescia, Italy
Purpose. The Flattening Filter Free (FFF) modality of the LINAC generates an unflattened X-ray beam with a dose rate up to 5 times (1200 MU/min) the maximum dose rate of a standard flattened beam. Aim of this study is to take advantage of high dose rate to spare treatment time for left breast breath-holding patients and to
201
deliver an equal or better treatment in dose distribution. Here a 6 MV three-fields FFF-IMRT technique is proposed and compared to the standard two tangential 3D-CR conformal radiotherapy (3D-CR). Methods. Our 6 MV three-fields IMRT technique adds a slightly tilted beam to the usual two tangential beams. The low modulation allows the maximum dose rate. For a group of 22 patients undergoing left breast treatment with ABC, a comparison was made between 3D-CR standard treatments and FFF-IMRT. 3D-CR plans were calculated by CMS XIOÒ (v.5.11 convolution superposition algorithm) and MonacoÒ (v.5.11.02 collapsed cone algorithm), FFF-IMRT plans by MonacoÒ (v.5.11.02 Monte Carlo algorithm). For plan comparison, 14 indicators were examined by a paired Student T-test to assess statistical significance of differences (p < 0.05). Assessed indicators are listed below: Left lung: V 20 Gy , V 10 Gy Heart: Mean Dose, V 25 Gy Right breast: V 2 Gy
Table 1 Table shows for comparison the mean value and range of statistically significant indicators (listed in first column) for 3D-CR and FFF-IMRT treatment plans. The respective p-values (p < 0.05) are also shown in last column. Indicator
3D-CR Mean value
CTV:V 98% Patient: Max dose (D1% ) 42.4 Gy Patient: Max dose (D1% ) 50 Gy Conformity Index Treatment time 2.65 Gy/fraction Treatment time 2 Gy/fraction Apnoeas 2.65 Gy/fraction Apnoeas 2 Gy/fraction
81.7% 40.7 Gy 47.9 Gy 0.68 13.9 min 13.7 min 5 5
FFF-IMRT Range
69%–95% 38.1 Gy–42.3 Gy 45.7 Gy–49.5 Gy 0.57–0.77 12.5 min–14.9 min 12.2 min–15.9 min 6–3 8–3
Mean value 85.8% 39.7 Gy 45.2 Gy 0.75 12.1 min 11.9 min 3 3
p-value Range
80%–90% 37.1 Gy–41.2 Gy 41.6 Gy–48.1 Gy 0.66–0.81 11.9 min–12.4 min 10.8 min–12.3 min – –
Threshold p = 0.05 0.012 0.024 0.014 <0.001 <0.001 0.003 <0.001 0.029
Figure 1. Figure shows a comparison between cumulative DVHs of a couple of plans. In this case FFF-IMRT (dashed lines) technique achieves the same (patient and right breast) or better OAR sparing (heart and left lung) than 3D-CR (continuous lines) ensuring at the same time a slightly better target coverage (PTV and CTV).
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Abstracts / Physica Medica 56 (2018) 133–278
Patient: Maximum Dose (D1% Þ PTV: V 95% , Maximum Dose (D1% Þ, V 105% (cm3), V 105% (%), Conformity Index (as defined in MonacoÒ v.5.11.02) CTV: V 98% Apnoeas number Treatment time Overall treatment times were evaluated for 3D-CR and FFF-IMRT plans by simulating a patient with a 25 s breath hold phase and a breath recover phase of 30 s. Times for patient set-up, portal imaging and treatment room leaving were also taken into account (total 600 s). Results. Significant differences were found for the indicators listed in Table 1. FFF-IMRT plans showed better CTV coverage, high doses (hot spots) control and conformity. All the FFF-IMRT plans were faster and achieved a mean time gain of 15.1% (2%–18%) for 50 Gy, 2 Gy/ fraction prescriptions and 14.9% (4%–18%) for 42.40 Gy, 2.65 Gy/fraction prescriptions, and a mean reduction of apnoeas number by two. Conclusions. The FFF-IMRT technique delivers an equal or better dose distribution with a significant reduction of treatment time and number of apnoeas, substantially improving patient comfort. https://doi.org/10.1016/j.ejmp.2018.04.236
226. Rigid and deformable image registration of CatalystTM optical surface scanning system Stefania Pallotta a,b, Malin Kugele c,d, Laura Redapi a, Livia Marrazzo b, Cinzia Talamonti a,b, Sofie Ceberg d a Department of Biomedical, Experimental and Clinical Sciences ‘‘Mario Serio”, University of Florence, Florence, Italy b Medical Physics Unit AOU Careggi, Florence, Italy c Department of Hematology, Oncology and Radiation Physics, Skåne University Hospital, Lund, Sweden d Medical Radiation Physics, Department of Clinical Sciences, Lund University, Lund, Sweden
Purpose. CatalystTM (C-RAD Positioning AB, Uppsala, Sweden) is an optical surface scanning (OSS) system used for patient setup verification in radiotherapy. In this study we have investigated its accuracy
in respect to the registration algorithm (rigid or elastic) and the reference surface (extracted from CT or acquired with the OSS system), using a deformable phantom and CBCT data as reference. Methods. An in-house build deformable phantom (Sliced Mary) capable of realistic body movements and deformations and containing anatomical details and targets (Fig. 1) was used. The phantom was deliberately deformed and positioned at the iso-center with the CatalystTM guidance. 8 deformations were tested (torsions, breast and abdomen enlargement) on 3 targets. For each deformation a CBCT was acquired and registered on planning CT. For comparison purposes the same procedure was repeated using also 3 rigid displacements without deforming the phantom. CatalystTM performance was tested in respect to the reference images (CT or OSS) the registration algorithm (rigid or elastic) and the applied phantom displacement ( rigid or deformable). The mean absolute differences between CBCT and CatalystTM registration (Dx; Dy; Dz; Drot; Dpitch; Droll) were evaluated. A Student’s ttest was carried out (p < 0.05). Results. The mean absolute differences between CatalystTM and CBCT registration, using OSS as reference, were less than 1.1 mm and 0.4° and 0.8mm and 0.7° for deformable and rigid displacements respectively (Table 1). Small differences between deformable and rigid algorithm were found, significant only for y (p = 0.02) and pitch (p = 0.04). Using CT as reference worse results were obtained. Small differences between deformable and rigid algorithm were found, significant only for roll (p = 0.01). Conclusions. Overall, the smallest differences compared to CBCT were found when CatalystTM used OSS as reference. Less accurate results were obtained using CT as reference. No benefit in the use of deformable algorithm was highlighted. https://doi.org/10.1016/j.ejmp.2018.04.237
227. MR Diffusion Tensor Imaging fiber tractography of thalamocortical and optical radiation tracts: Comparison between probabilistic fiber tracking and evoked potential recorded in epileptic patients D. Lizio a, S. Nici a, E. Artuso a, L. Berta a, M. Rizzi b, I. Sartori b, P.E. Colombo a, A. Torresin a
Table 1 Displacement
Algorithm
Reference
Dx½mm
Dy½mm
Dz½mm
Drot½
Dpitch½
Droll½
deformable deformable rigid rigid deformable deformable rigid rigid
elastic rigid elastic rigid elastic rigid elastic rigid
OSS OSS OSS OSS CT CT CT CT
1.1 ± 1.2 1.9 ± 1.5 0.7 ± 0.4 0.9 ± 0.9 2.6 ± 1.0 2.2 ± 1.6 2.1 ± 1.0 0.8 ± 0.8
0.6 ± 0.5 1.1 ± 0.8 0.8 ± 0.5 0.5 ± 0.4 1.2 ± 0.9 1.5 ± 1.9 1.0 ± 0.8 0.9 ± 0.6
1.0 ± 0.9 1.3 ± 1.0 0.8 ± 0.6 1.0 ± 1.2 1.3 ± 0.9 1.6 ± 1.4 1.7 ± 0.7 2.5 ± 1.0
0.4 ± 0.5 0.6 ± 0.6 0.3 ± 0.1 0.2 ± 0.2 0.6 ± 0.4 0.8 ± 0.5 0.4 ± 0.2 0.6 ± 0.1
0.4 ± 0.4 0.8 ± 0.6 0.7 ± 0.5 1.1 ± 0.6 0.8 ± 0.5 0.8 ± 0.4 0.8 ± 0.4 0.9 ± 0.4
0.6 ± 0.4 0.4 ± 0.4 0.7 ± 0.3 0.6 ± 0.4 1.2 ± 0.5 0.7 ± 0.5 1.3 ± 0.6 1.0 ± 0.2
225. Low modulated 6 MV Flattening Filter Free Intensity Modulated Radiation Therapy (FFF-IMRT) for left breast treatments with Active Breath CoordinatorTM (ABC): A feasibility study P.A. De Lucia a,b, M. Chieregato b, M. Galelli b, S. Ren Kaiser b, C. Bassetti b, L. Donadoni c, A. Huscher c, I.S. Villa c, M. Bignardi c a Scuola di Specializzazione in Fisica Medica, Università degli studi di Milano, Milano, Italy b Fondazione Poliambulanza Istituto Ospedaliero, Fisica Sanitaria, Brescia, Italy c Fondazione Poliambulanza Istituto Ospedaliero, Radioterapia, Brescia, Italy
Purpose. The Flattening Filter Free (FFF) modality of the LINAC generates an unflattened X-ray beam with a dose rate up to 5 times (1200 MU/min) the maximum dose rate of a standard flattened beam. Aim of this study is to take advantage of high dose rate to spare treatment time for left breast breath-holding patients and to
201
deliver an equal or better treatment in dose distribution. Here a 6 MV three-fields FFF-IMRT technique is proposed and compared to the standard two tangential 3D-CR conformal radiotherapy (3D-CR). Methods. Our 6 MV three-fields IMRT technique adds a slightly tilted beam to the usual two tangential beams. The low modulation allows the maximum dose rate. For a group of 22 patients undergoing left breast treatment with ABC, a comparison was made between 3D-CR standard treatments and FFF-IMRT. 3D-CR plans were calculated by CMS XIOÒ (v.5.11 convolution superposition algorithm) and MonacoÒ (v.5.11.02 collapsed cone algorithm), FFF-IMRT plans by MonacoÒ (v.5.11.02 Monte Carlo algorithm). For plan comparison, 14 indicators were examined by a paired Student T-test to assess statistical significance of differences (p < 0.05). Assessed indicators are listed below: Left lung: V 20 Gy , V 10 Gy Heart: Mean Dose, V 25 Gy Right breast: V 2 Gy
Table 1 Table shows for comparison the mean value and range of statistically significant indicators (listed in first column) for 3D-CR and FFF-IMRT treatment plans. The respective p-values (p < 0.05) are also shown in last column. Indicator
3D-CR Mean value
CTV:V 98% Patient: Max dose (D1% ) 42.4 Gy Patient: Max dose (D1% ) 50 Gy Conformity Index Treatment time 2.65 Gy/fraction Treatment time 2 Gy/fraction Apnoeas 2.65 Gy/fraction Apnoeas 2 Gy/fraction
81.7% 40.7 Gy 47.9 Gy 0.68 13.9 min 13.7 min 5 5
FFF-IMRT Range
69%–95% 38.1 Gy–42.3 Gy 45.7 Gy–49.5 Gy 0.57–0.77 12.5 min–14.9 min 12.2 min–15.9 min 6–3 8–3
Mean value 85.8% 39.7 Gy 45.2 Gy 0.75 12.1 min 11.9 min 3 3
p-value Range
80%–90% 37.1 Gy–41.2 Gy 41.6 Gy–48.1 Gy 0.66–0.81 11.9 min–12.4 min 10.8 min–12.3 min – –
Threshold p = 0.05 0.012 0.024 0.014 <0.001 <0.001 0.003 <0.001 0.029
Figure 1. Figure shows a comparison between cumulative DVHs of a couple of plans. In this case FFF-IMRT (dashed lines) technique achieves the same (patient and right breast) or better OAR sparing (heart and left lung) than 3D-CR (continuous lines) ensuring at the same time a slightly better target coverage (PTV and CTV).
202
Abstracts / Physica Medica 56 (2018) 133–278
Patient: Maximum Dose (D1% Þ PTV: V 95% , Maximum Dose (D1% Þ, V 105% (cm3), V 105% (%), Conformity Index (as defined in MonacoÒ v.5.11.02) CTV: V 98% Apnoeas number Treatment time Overall treatment times were evaluated for 3D-CR and FFF-IMRT plans by simulating a patient with a 25 s breath hold phase and a breath recover phase of 30 s. Times for patient set-up, portal imaging and treatment room leaving were also taken into account (total 600 s). Results. Significant differences were found for the indicators listed in Table 1. FFF-IMRT plans showed better CTV coverage, high doses (hot spots) control and conformity. All the FFF-IMRT plans were faster and achieved a mean time gain of 15.1% (2%–18%) for 50 Gy, 2 Gy/ fraction prescriptions and 14.9% (4%–18%) for 42.40 Gy, 2.65 Gy/fraction prescriptions, and a mean reduction of apnoeas number by two. Conclusions. The FFF-IMRT technique delivers an equal or better dose distribution with a significant reduction of treatment time and number of apnoeas, substantially improving patient comfort. https://doi.org/10.1016/j.ejmp.2018.04.236
226. Rigid and deformable image registration of CatalystTM optical surface scanning system Stefania Pallotta a,b, Malin Kugele c,d, Laura Redapi a, Livia Marrazzo b, Cinzia Talamonti a,b, Sofie Ceberg d a Department of Biomedical, Experimental and Clinical Sciences ‘‘Mario Serio”, University of Florence, Florence, Italy b Medical Physics Unit AOU Careggi, Florence, Italy c Department of Hematology, Oncology and Radiation Physics, Skåne University Hospital, Lund, Sweden d Medical Radiation Physics, Department of Clinical Sciences, Lund University, Lund, Sweden
Purpose. CatalystTM (C-RAD Positioning AB, Uppsala, Sweden) is an optical surface scanning (OSS) system used for patient setup verification in radiotherapy. In this study we have investigated its accuracy
in respect to the registration algorithm (rigid or elastic) and the reference surface (extracted from CT or acquired with the OSS system), using a deformable phantom and CBCT data as reference. Methods. An in-house build deformable phantom (Sliced Mary) capable of realistic body movements and deformations and containing anatomical details and targets (Fig. 1) was used. The phantom was deliberately deformed and positioned at the iso-center with the CatalystTM guidance. 8 deformations were tested (torsions, breast and abdomen enlargement) on 3 targets. For each deformation a CBCT was acquired and registered on planning CT. For comparison purposes the same procedure was repeated using also 3 rigid displacements without deforming the phantom. CatalystTM performance was tested in respect to the reference images (CT or OSS) the registration algorithm (rigid or elastic) and the applied phantom displacement ( rigid or deformable). The mean absolute differences between CBCT and CatalystTM registration (Dx; Dy; Dz; Drot; Dpitch; Droll) were evaluated. A Student’s ttest was carried out (p < 0.05). Results. The mean absolute differences between CatalystTM and CBCT registration, using OSS as reference, were less than 1.1 mm and 0.4° and 0.8mm and 0.7° for deformable and rigid displacements respectively (Table 1). Small differences between deformable and rigid algorithm were found, significant only for y (p = 0.02) and pitch (p = 0.04). Using CT as reference worse results were obtained. Small differences between deformable and rigid algorithm were found, significant only for roll (p = 0.01). Conclusions. Overall, the smallest differences compared to CBCT were found when CatalystTM used OSS as reference. Less accurate results were obtained using CT as reference. No benefit in the use of deformable algorithm was highlighted. https://doi.org/10.1016/j.ejmp.2018.04.237
227. MR Diffusion Tensor Imaging fiber tractography of thalamocortical and optical radiation tracts: Comparison between probabilistic fiber tracking and evoked potential recorded in epileptic patients D. Lizio a, S. Nici a, E. Artuso a, L. Berta a, M. Rizzi b, I. Sartori b, P.E. Colombo a, A. Torresin a
Table 1 Displacement
Algorithm
Reference
Dx½mm
Dy½mm
Dz½mm
Drot½
Dpitch½
Droll½
deformable deformable rigid rigid deformable deformable rigid rigid
elastic rigid elastic rigid elastic rigid elastic rigid
OSS OSS OSS OSS CT CT CT CT
1.1 ± 1.2 1.9 ± 1.5 0.7 ± 0.4 0.9 ± 0.9 2.6 ± 1.0 2.2 ± 1.6 2.1 ± 1.0 0.8 ± 0.8
0.6 ± 0.5 1.1 ± 0.8 0.8 ± 0.5 0.5 ± 0.4 1.2 ± 0.9 1.5 ± 1.9 1.0 ± 0.8 0.9 ± 0.6
1.0 ± 0.9 1.3 ± 1.0 0.8 ± 0.6 1.0 ± 1.2 1.3 ± 0.9 1.6 ± 1.4 1.7 ± 0.7 2.5 ± 1.0
0.4 ± 0.5 0.6 ± 0.6 0.3 ± 0.1 0.2 ± 0.2 0.6 ± 0.4 0.8 ± 0.5 0.4 ± 0.2 0.6 ± 0.1
0.4 ± 0.4 0.8 ± 0.6 0.7 ± 0.5 1.1 ± 0.6 0.8 ± 0.5 0.8 ± 0.4 0.8 ± 0.4 0.9 ± 0.4
0.6 ± 0.4 0.4 ± 0.4 0.7 ± 0.3 0.6 ± 0.4 1.2 ± 0.5 0.7 ± 0.5 1.3 ± 0.6 1.0 ± 0.2