The ideal proton facility for moving tumors

Transcription

1 The ideal proton facility for moving tumors Martijn Engelsman 1

2 The organizers asked: Discuss the ideal proton facility for moving tumors While not shunning: To introduce unpopular opinions To raise controversial questions To discuss failures 2

3 Clinical landscape Indication Children CSI + anesthesia Eyes Skull base / head and neck Breast Prostate Lung conventional Lung hypo-fractionation Sarcoma Gastro-intestinal Pancreas Liver Hodgkin s disease Indications in green/orange have been approved (under constraints) by Dutch healthcare insurance Nr of patients: We want to / will treat everything using IMPT! 3

4 Current IMPT usage 4

5 Physics landscape > Patients treated with proton therapy 100 Percent ambition of (new) proton centers IMPT All indications 50 Studies on interplay effect in proton therapy ±10 Patients treated with re-painting ±0 Patients treated with re-painting and IMPT 5

6 Rescanning variables Spot size Different answer for: Lateral spot overlap - Each indication? Distal spot overlap - Each patient? Volumetric or layer repainting Number of rescans Number of treatment fractions Number of beams in the plan Simultaneous gating or breath-hold Iso-layer or scaled-rescanning Spot-, line- or contour-scanning Uniform, phase-controlled, random, time-delay, Layer changing time (vendor dependent) Re-image and re-plan approach 6

7 While you write papers The clinical physicist and the patients 7

8 Don t aim for the moon (it s leaving us anyway at 3.8 cm per year) 100 % Let s be practical! 80 % 8

9 Clinical reality A survey of 12 US-based proton therapy centers on motion (effects) mitigation 100% Percentage of institutes 75% 50% 25% 0% Margins Breath-hold Gating Repainting A bit too practical: let s do better than that! 9

10 80 % What is needed? Some facility choices 10

11 Beamlines Gantries Fixed beams 11

12 Modality Passive-scattering 20 % Uniform scanning Pencil-beam scanning 80 % 12

13 Layer switching time > 3 seconds seconds 80 % 80 milliseconds 13

14 Beam availability Multiple rooms (1 accelerator) 80 % 8 second field delivery 100 % Continuous beam sharing 100 % Dedicated accelerator 100 % 14

15 Imaging Orthogonal X-rays 10 % Cone-beam CT 80 % (dual-energy) CT 90 % What to do with these images? -> 80% solution 15

16 Volumetric imaging location Off-line Trolley system In-room At isocenter 10 % 20 % 80 % 90 % Bring your workflow to your patient. Not your patient to your workflow. 16

17 Dose degradation mitigation Breath-hold / gating <0.3s lag-time Repainting <1.5s layer switching Increased control over TPS, TDS and patient geometry required (4D) Tracking 17

18 Dose validation On-line dose recalculation 80 % But we will need something more to assess the effectiveness of our dose degradation management techniques Prompt gamma PET in-vivo Currently 18

19 Do we need R&D? in our clinic 19

20 Proton technology waves Research Current patients Future patients The clinic 20

21 Why is development slow? R&D papers focus on limited part of the problem. No comprehensive overview. It provides ideas, not full technological solutions Clinical reality is always different Development is not sexy (or rewarded ) The clinic has too little time Financial pressures Chaotic workflow Development is not sexy New functionality versus widely supported solutions It s a three-party problem 21

22 Collaboration R&D development The clinic The vendor (with R&D) TPS, OIS, TDS, 22

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24 Need for 3-party collaboration Are you happy about the electronic integration between TPS, OIS and TDS? For a not yet too difficult treatment / workflow: We do a lot of in-house manipulations to make our OIS work with protons. The integration between TPS and OIS is acceptable. The challenge is mainly in the communication between OIS and TDS. There is no integration whatsoever. No way this system can be integrated. 24

25 Dose delivery variables Spot size Lateral spot overlap Distal spot overlap Volumetric or layer repainting Number of rescans Number of treatment fractions Number of beams in the plan Simultaneous gating or breath-hold Iso-layer or scaled-rescanning Spot-, line- or contour-scanning Uniform, phase-controlled, random, time-delay, Layer changing time (vendor dependent) Re-image and re-plan approach Different answer for: - Each indication? - Each patient? 25

26 Dose-degradation prediction and control Comprehensive peer-reviewed studies per indication, with large patient groups 4D error simulation platform for do-it-yourself analysis. Let s aim for a community-supported freeware platform 26

27 Departmental focus For the next five years Let s not compete in publications, but in the clinic! 27

28 Let s make things better The future patient is around the corner Thank you Martijn Engelsman m.engelsman@tudelft.nl 28