Our Department: structure and organization

Transcription

1 EORTC meeting for Radiation Therapy Technologists: RTT s role in the modernization of radiotherapy 10th October 2014, Villejuif (Grand Paris), France Elekta Stereotactic Body Frame: transmission modelled by Monte Carlo and Collapsed Cone algorithm for VMAT treatment planning Ilenia Iarrusso University of Torino, Italy Equipe: 4 Physicists + 4 Dosimetrists Management of DICOM images; Contouring of some OAR (Organ At Risk) in CT simulation scan; Planning of 3D treatment plans; Patient Specific Quality Assurance (the focal point of this study); LINAC QC. 1

2 Our Department: structure and organization I will speak about Our study: purpose, methods and discussion Patient specific Quality Assurance control Our Department: structure and organization I will speak about Our study: purpose, methods and discussion Patient specific Quality Assurance control 2

3 ELEKTA MOSAIQ Vers Philips Brilliance Big Bore CT-Simulation, Tumor L.O.C., 4D-CT; Clarity LINAC 1 Elekta SL75 X 6; Align RT Velocity LINAC 2 Elekta Synergy X 4-6, MLCi2, cone beam CT, Clarity, Intuity Elekta ABAS; Anatom-e Atlas based autosegmentation LINAC 3 Elekta Precise X ; e, MLCi2, EPID, Clarity Elekta Monaco 3.3 Monte-Carlo Systems Film-and paperless since 2010 LINAC 4 Elekta Axesse X ; e, Beam Modulator, cone beam CT, Integrity 1.1, Symmetry, Intuity, 4D-Autoscan Gammknife Perfexion 2014 Elekta/Nucletron Masterplan vers. 4.3 IORT Linac Novac-7 NRT Connection to unit 1 Radioterapia SGAS (3 Linacs) Distance 3 km Connection to unit 2 Radioterapia S. Anna (1 Linac) Distance 500 m 2 Linac Siemens Primus LINAC Elekta Synergy X 6-18; e, MLC, EPID LINAC Elekta Synergy X 6; e, MLC, EPID HDR Brachytherapy The Department of Radiation Oncology of University of Torino is directed by Prof. Umberto Ricardi and the staff is composed of: 9 Radiation Oncologists 13 Residents 4 Medical Physicist 4 Dosimetrists 15 RTT Dedicated ward to assist critical patients and a Day Hospital for chemotherapy and to carry out a supportive care. 3

4 11/19/2014 4

5 Our Department: structure and organization I will speak about Our study: purpose, methods and discussion Patient specific Quality Assurance control This is the phantom used by Dosimetrist for Patient Specific QA 5

6 Scandidos Delta 4 Detector type Diode Resolution(mm) 5/10 # of Detectors 1069 Max field size 20 Weight kg (detector/phantom) 24 - VMAT plan is approved. - Plan parameters are copied to a phantom (Verification Plan) UNIVERITA DEGLI STUDI DI TORINO 6

7 - Delta 4 phantom CT Phantom density override and couch absorption For no-coplanar arcs, beams are arranged to remove couch angle - Positioning and centering of Delta 4 phantom on the couch 7

8 The planar measured dose is compared to that calculated by TPS - Dosimetrist and Medical Physicist analyze the results 8

9 - The agreement is acceptable if the percentage of points with value of Gamma Index < 1 is 90%; When this value is < 90%, we perform a specific procedure: Percentage of point 90% Yes No VMAT QA is approved Verification of workflow Measure is repeated Re-export VMAT QA is approved Step and Shoot VMAT QA is approved Our Department: structure and organization I will speak about Our study: purpose, methods and discussion Patient specific Quality Assurance control 9

10 11/19/2014 The purpose of this study was to verify the influence of the transmission of the Elekta Stereotactic Body Frame (ESBF) in VMAT treatment planning: - Selection of one patient with Liver tumor for Stereotactic Body Radiation Therapy (SBRT) and planning of a treatment of 60 Gy in three fractions, using beams with energy of 6 MeV. 10

11 - Acquisition of CT images of the Delta 4 phantom, positioning it on the Elekta Stereotactic Body Frame (ESBF) - Calculation of VMAT QA with and without ESBF, using Monte Carlo and Collapsed Cone algorithm. Dose calculated using Collapsed Cone algorithm with and without ESBF Dose calculated using Monte Carlo algorithm with and without ESBF 11

12 - Verification of the plan, positioning the phantom with and without the ESBF on the couch and acquisition of the dose. - Analysis of results and comparison between the two TPS 12

13 Gamma Index passing rates for the two considered algorithms Monaco Masterplan Monaco Masterplan Without ESBF absorption With ESBF absorption Gamma Index 2mm / 2% Gamma Index 3mm / 3% Evaluation of ESBF absorption for VMAT treatment by means of patient specific QA procedure If absorption is considered, we can find lower agreement between measured and calculated doses Metal artifacts? Considering ESBF absorption, Monaco TPS better than Masterplan TPS AAPM TG 119 (90%). 13

14 The use of ESBF introduces an increased value of uncertainty in treatment planning for liver SBRT Monte Carlo algorithm may overcome this uncertainties 14