KRISTOFFER PETERSSON, MEDICINSK STRÅLNINGSFYSIK, LUND

Transkript

1 A deliverability comparison of equivalent dualarc VMAT plans generated in two different TPSs KRISTOFFER PETERSSON, MEDICINSK STRÅLNINGSFYSIK, LUND Plan quality Pareto fronts 1

2 Pareto front evaluation Method Better Objective OAR TPS 1 TPS 2 Worse Better Objective Target Worse Area under the plan (AUP) D mean OAR V PTV, <95% 2

3 Area under the plan (AUP) AUP i = Δ iy D mean OAR Δ ix V PTV, <95% Area under the plan (AUP) AUP i = Δ iy D mean OAR Δ ix V PTV, <95% 3

4 Area under the plans (AUPs) AUPs = AUP i =.. Δ ny Δ 2y Δ 1y D mean OAR Δ 1x Δ 2x V PTV, <95% Δ nx D mean Parotis dx (Gy) D mean Parotis dx (Gy) D mean Parotis dx (Gy) Pareto fronts H&N 1 in H&N 2 in 70 H&N 3 in D mean Parotis dx (Gy) D mean Parotis dx (Gy) D mean Parotis dx (Gy) H&N 1 in H&N 2 in 70 H&N 3 in AUPs Wilcoxon Wilcoxon H&N p= p=0.04 H&N p< p=0.84 H&N p= p=0.88 4

5 Pareto fronts D mean Parotis dx (Gy) D mean Parotis dx (Gy) D mean Parotis dx (Gy) H&N 1 in H&N 2 in 70 H&N 3 in D mean Parotis dx (Gy) D mean Parotis dx (Gy) D mean Parotis dx (Gy) H&N 1 in H&N 2 in 70 H&N 3 in Pareto fronts Abdomen 1 in Abdomen 1 in Abdomen 2 in Abdomen 2 in AUPs Wilcoxon Wilcoxon Abdomen p= p<0.01 Abdomen p= p=0.84 Abdomen p= p= Abdomen 3 in Abdomen 3 in

6 Pareto fronts 5 Abdomen 1 in Abdomen 2 in 5 Abdomen 1 in Abdomen 2 in Abdomen 3 in Abdomen 3 in D mean Hemisphere dx(gy) Intracranial 1 in Intracranial 2 in Pareto fronts D mean Hemisphere dx(gy) Intracranial 1 in Intracranial 2 in Intracranial 1 Intracranial 2 Intracranial 3 AUPs Wilcoxon Wilcoxon p= p= p< p< p< p=0.71 D mean Cochlea dx (Gy) D mean Hippocampus sin(gy) Intracranial 3 in D mean Cochlea dx (Gy) D mean Hippocampus sin(gy) Intracranial 3 in 6

7 Pareto fronts D mean Hemisphere dx(gy) Intracranial 1 in Intracranial 2 in D mean Hemisphere dx(gy) Intracranial 1 in Intracranial 2 in D mean Cochlea dx (Gy) D mean Hippocampus sin(gy) Intracranial 3 in D mean Cochlea dx (Gy) D mean Hippocampus sin(gy) Intracranial 3 in Pelvis 1 in Pelvis 2 in Pelvis 3 in Pareto fronts Pelvis 1 in Pelvis 2 in Pelvis 3 in AUPs Wilcoxon Wilcoxon Pelvis p= p=0.47 Pelvis p= p=0.04 Pelvis p= P<0.01 7

8 Pareto fronts Pelvis 1 in Pelvis 2 in Pelvis 3 in Pelvis 1 in Pelvis 2 in Pelvis 3 in Plan quality Conclusions: Significant difference in plan quality In fronts superior for: 1 Intracranial fronts superior for: 1 H&N, 1 Abdomen, 1 Intracranial, 2 Pelvis In fronts superior for: 1 H&N 1 Abdomen, 1 Intracranial, 1 Pelvis fronts superior for: 1 Pelvis 8

9 Inledning Bakgrund RaySearch Laboratories SharePlan TM Automatisk konvertering av tomoterapi dosplaner step and shoot IMRT planer (levereras på vanlig linac). Välfungerande men begränsat användningsområde. Inledning Bakgrund RaySearch Laboratories Modul för Fallback planning Vidareutveckling av SharePlan funktionen Automatisk konvertering av alla typer av dosplaner alla modaliteter som finns tillgängliga på en vanlig linac. 3D conformal radiation therapy (CRT) Step and shoot IMRT Sliding window IMRT VMAT 9

10 Syfte Kontrollera levererbarheten automatiskt genererade backupplaner skapade i. Dual arc VMAT planer Jämfört med motsvarande planer som skapats i. Kontrollera # MU i planerna Jämfört med motsvarande planer som skapats i. Kontrollera mot levererbarhet Korrelation?

11 Metodik 2 st planer skapas i 6MV Dual arc VMAT Pareto optimala 1 Pareto front per patientfall 12 Patient fall 3 H&N 3 hjärntumörer 3 buktumörer 3 tumörer i bäckenet Automatiskt genererade backup planer skapas i Baseras på planer 3 backup planer per plan Olika Target vs. OAR viktfaktorer 00:1, 0:1, :1 Samma inställningar/restriktioner Ex: Kollimatorvinkel: gantry kontrollpunktseparation: 2 Beräkningsgrid: 2.5 x 2.5 x 2.5 mm 3 Etc. 1 backup plan per plan sparas Bäst plankvalité Metodik 4 planer (2 +2 ) Levererade med en TrueBeam linac (Varian) Mätta med Delta 4 system (ScandiDos AB) 11

12 ΔD m δ y Γ(r m,r c ) D c, r c δ(r m,r c ) Δd m r c r c -r m D m, r m x Metodik Gamma analys Krav: Dosdifferens 3% DTA 2 mm Tröskelvärde % Kliniskt acceptabel plan: 95 % godkända mätpunkter Statistisk metod: Wilcoxon signed rank test 12

13 Resultat Gamma analys Andel godkända mätpunkter Signifikant högre för planer jmf. Wilcoxon, (p<0.001) 93.0% 0%, 98.6% 0% 66/2 > 7/2 < Enbart 3 planer < 95%, ej kliniskt acceptabla. # MU i planerna Signifikant fler MU i planer jmf. motsvarande plan Wilcoxon, (p<0.001) I medel: 29% # MU korrelerar med grad av levererbarhet (andel godkända mätpunkter) Pearson product moment correlation method r = 0.77 p<0.001 Korrelation mellan # MU och grad av levererbarhet Andel godkända mätpunkter[%] MU Pearson korrelation r= 0.77 p<

14 Två patientfall med lägre värden Andel godkända mätpunkter[%] r = 0.79 p< Abdomen 2 Abdomen MU Andel godkända mätpunkter [%] r = 0.89 p< H&N 2 H&N MU Arc 1 av 2 Arc 1 av 2 14

15 Arc 1 av 2 Arc 1 av 2 Diskussion Plankvalité Plankvalité har kontrollerats Pareto front utvärdering Jämförbar mellan systemen Signifikant skillnad för 5/12 fall front bättre för: 1 H&N 1 Buktumör 1 hjärntumör 1 tumör i bäckenet front bättre för : 1 tumör i bäckenet

16 Slutsats Signifikant högre levererbarhet för planer vs. planer. Antal MU signifikant högre för planer vs. planer (29% i medel). OBS! Enbart 3/4 planer var ej kliniskt acceptabla(< 95%) Antalet MU i en plan korrelerade signifikant med dess grad av levererbarhet. Manus Differences in plan quality for available treatment techniques: VMAT, IMRT (SW and SS), 3DCRT (non coplanar) Evaluation methods Objective value, CGA Approach standard plans created in TomoTherapy planning system the 12 cases Plans with the highest plan quality clinically available: Field width: 1.05 cm Pitch: Modulation factor: 5 Backup plans created and evaluated in 16

17 E E E E E E 04 Objective values Optimized # iterations DCRT SS IMRT SW IMRT Dual Arc 1.00E E E E E E 04 After Backup generation DCRT SS IMRT SW IMRT Dual Arc After optimization (approximate dose): No significant difference between techniques directly after Backup gen. If # iterations is optimized: VMAT quality improves significantly VMAT significantly superior to other techniques SS IMRT significantly superior to 3DCRT 1.00E E E E E E 04 Optimized # iterations DCRT SS IMRT SW IMRT Dual Arc 1.00E E E E E E 04 After Backup generation DCRT SS IMRT SW IMRT Dual Arc After final dose: SS IMRT significantly superior to SW IMRT If # iterations is optimized: VMAT quality improves significantly VMAT significantly superior to other techniques Objective values After optimization (approximate dose): If Reduce OAR is used: Plan quality improves significantly for all available techniques SS IMRT significantly superior to VMAT 1.00E E E E E E 04 Direkt efter Backup skapandet E E E E E E 04 Reduce OAR After final dose: If Reduce OAR is used: No significant improvement No significant difference between techniques 1.00E E E E E 03 3DCRT SS IMRT SW IMRT Dual Arc Direkt efter Backup skapandet 1.00E E E E E 03 3DCRT SS IMRT Dual Arc Reduce OAR 1.00E E DCRT SS IMRT SW IMRT Dual Arc 3DCRT SS IMRT Dual Arc 17

18 CGA Method Inspired by VGA Visual Grading Analysis Determine image quality (Radiology) Dual arc VMAT plans, 7 beam SS IMRT, 7 beam 3DCRT (non coplanar) plans Demonstrated for ROs (individually) Plans side by side Mimic ordinary clinical rounds Dose distributions DVHs ROI data Clinical assessment Identify clinical relevant differences between plans CGA Method ROs grade plans and motivate their opinion A B C D E SS IMRT/3DCRT plan considerably better than the VMAT plan SS IMRT/3DCRT plan somewhat better than the VMAT plan SS IMRT/3DCRT plan as good as the VMAT plan VMAT plan somewhat better than the SS IMRT/3DCRT plan VMAT plan considerably better than the SS IMRT/3DCRT plan 18

19 CGA Results (so far!) 1.00E+01 Optimized # iterations 1.00E E E E E DCRT SS IMRT Dual Arc CGA Results (so far!) Hot spots are not penalized enough in the optimization Problem for complex cases Problem for IMRT techniques 19

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