Head and Neck Treatment Planning: A Comparative Review of Static Field IMRT Rapid Arc Tomotherapy HD

Transcription

1 Good Morning

2 Head and Neck Treatment Planning: A Comparative Review of Static Field IMRT Rapid Arc Tomotherapy HD Barbara Agrimson, BS RT(T)(R), CMD Steve Rhodes, BS RT(T), CMD

3 Disclaimer This presentation will mention equipment by trade name. This does not mean that we endorse the product but rather we mention it because it is what we use at our facility.

4 Objectives of Presentation To review the evolution of head and neck treatment at Oregon Health and Science University (OHSU) over the past ten years. To share basic contouring techniques of the head and neck area. To learn the planning approach of head and neck cancers at OHSU using static field IMRT, Varian Rapid Arc, and Tomotherapy. To identify similarities and differences between static field IMRT, Varian Rapid Arc, and Tomotherapy, for head and neck treatment plans.

5 I. Review

6 The OHSU Experience Evolution of Head and Neck Treatment 2005: Static Field IMRT Varian 21ex Pinnacle TPS Impac RVS 2007: Varian Upgrade Varian Trilogy CBCT Eclipse TPS Aria RVS 2008 paperless

7 The OHSU Experience Evolution of Head and Neck Treatment 2010: Rapid Arc Varian Trilogy Eclipse TPS Aria RVS

8 The OHSU Experience Evolution of Head and Neck Treatment 2011: Tomotherapy Tomo HD How do plans compare? Downtime Tomotherapy TPS Learning curve Plan quality? Outcome Generate plans for comparison» Staff acceptance Backup plans» Downtime

9 Current OHSU Experience Three options for patients with head and neck cancers

10 Current OHSU Experience Most head and neck cancer patients are scheduled on Tomotherapy Approximately 100 HN patients treated each year Requires one Tomotherapy plan plus one backup plan of equal quality. Dosimetrist can choose Rapid Arc, IMRT or both, for back-up plan. Physician will select the most appropriate plan Plan comparison Objectives Imaging Treatment time Machine work-load

11 Current OHSU Experience From simulation to patient start date ~ 4-6 working days Dosimetrist Registers requested ancillary imaging; PET, MRI, CT Contours all structures in Eclipse; OAR and planning structures All structures needed for Tomotherapy planning are contoured in Eclipse Physician Reviews the registration and OAR contours Contours the CTV and PTV volumes Generates the planning objectives form

12 Current OHSU Experience Contours and CT dataset are exported to Tomotherapy for planning Plans are generated simultaneously in Tomotherapy and Eclipse. Physician evaluates completed plans Approves a plan for treatment Back-up plan will also be approved if Tomotherapy is the primary treatment Physics QA done on both plans

13 II. Contouring

14 Head and Neck Contours CT scan Philips Brillance Big Bore Contouring Eclipse v8.9 TPS with Wacom tablets

15 Tablet for Contouring and Planning

16 Artifact! =

17 Raw CT data set O-MAR Processed

18 Better = Dataset after using Philips O-MAR software function.

19 Common Anatomy Contoured Spinal Cord Cord+5mm Brainstem Brainstem+5mm Eyes Lens Optic nerves Mandible Parotids Cochlea's Submandibular glands Hyoid Larynx Constrictors Cervical Esophagus

20 Target Contours GTV GTV + margin = PTV High Dose (Hot Spot Here) CTV1 CTV1+3 mm = PTV1 CTV2 CTV2+3 mm = PTV2 2-3 mm margin between skin surface and PTV volumes Prevents severe acute skin reaction and late fibrosis of subcutaneous tissue

21 GTV Delineation using multiple imaging modalities

22

23 RTOG Contouring Atlas

24 Contours

25 Target Volumes CTV2 GTV CTV1

26 Artifact and Density Override

27 OAR/Target Overlap

28 Contouring Planning structures Dose Ring Wall Extraction tool 3mm margin 1 cm wide Control dose

29 Contouring Planning structures Normal Tissue Ring Copy Body Crop out of PTV with additional 1.5 cm margin Control dose

30 Contouring Planning structures Posterior Avoid Posterior expansion of the Cord+5mm Limit dose to posterior neck region

31 III. Planning Part A

32 Prescription Prescription (typical case) 100% isoline to cover 95% of the target volume (PTV high dose) Target and 2 nodal dose levels 200 cgy x 35 = 70 Gy PTV High Dose 180 cgy x 35 = 63 Gy PTV cgy x 35 = 56 Gy PTV56

33 Prescription OAR objectives Planning objectives form ( Love Note ) Planning OAR techniques Upper/lower PTV In air/ in tissue PTV s Subtract overlap OAR s from PTV s No margin

34 Planning Objectives (Case Specific) Dosi Love Note Cord < 45 Gy Cord+5mm < 50 Gy Brainstem < 50 Gy Brainstem+5mm<55 Gy Mandible ~ max < 70 or 72Gy No more than 5%>70 Gy Parotids L Parotid mean < 26 Gy R Parotid mean < 22 Gy

35 Planning Objectives (Case Specific) Dosi Love Note Hyoid max < 74 Gy Larynx mean < 60 Gy Constrictors mean < 50 Gy Cervical Esophagus mean < 35 Gy, max < 65 Gy Cochlea's R cochlea mean < 12 Gy L cochlea mean < 7 Gy

36 Miscellaneous Factors Patient specific Patient supine, halcyon board, aquaplast mask, "B headrest, shoulder retractors, knee sponge, align bb's on mask with ant chest tattoo. Shoulders Avoidance contours with Tomo plans Couch kick ~15 degrees with IMRT beams that may enter through shoulders.

37 Miscellaneous Factors Back-up plans Required with patients treated on the tomotherapy machine Machine down time Imaging challenges Physician approves both Tomo and Eclipse plans Both plans are printed and require physics QA and therapist verification Only one charge is billed for that case. Dosimetry work flow Simultaneous planning between Tomotherapy and Eclipse systems One Dosimetrist can work on Tomotherapy plan while another does the Eclipse plan

38 Miscellaneous Factors Department Splitting work load between machines Imaging The Physician will factor in the imaging quality of the machine when deciding the treatment machine for the patient. MVCT Daily on Tomotherapy kv CBCT Daily on Linac kv orthogonal pair As back-up, if needed Exactrac More complex OAR locations

39 kv CBCT vs MV CT

40 III. Planning Part B

41 Planning Specifics Static Field IMRT Rapid Arc Tomotherapy

42 Static IMRT Planning 9 Field beam arrangement 2 non-coplanar to avoid shoulders Sliding window delivery Collimator rotation Typically no rotation Beam energy 6 MV Unique planning contours Posterior neck avoidance Tissue Rings Dose hot spots Planning objectives 100% of dose to cover 95% of target volume

43 Planning Contours

44 Rapid Arc Planning Beam arrangement 2 full, 1 partial arc Field width of 15 cm total Collimator rotation 10 degrees CW and CCW Beam energy 6 MV Unique planning contours PTV in air/in tissue PTV superior/inferior Planning objectives 100% of dose to cover 95% of target volume

45 Tomotherapy Planning Jaw selection Pitch 1cm field width at beam batch.287 Regular verses Fine dose calculation Less degradation Takes longer to batch Longer optimization time Unique planning contours Separate out overlying structures to the PTV s Planning objectives 100% of dose to cover 95% of target volume Model after the Eclipse DVH

46 Overlap OAR s Overlap Priority built into planning software Not our preferred method based on physician expectation Utilize sub structures Optimize to these cropped structures Improves target coverage

47 Tomotherapy Planning Jaw Setting Delivery Time R Cochlea L Cochlea PTV coverage Sup/Inf slices 2.5 cm Width 6.3 min 2068 cgy 2183 cgy Marginal 1 cm Width 13.8 min 1435 cgy 1736 cgy Improved

48 Head and Neck Delivery Time Average Treatment Time 9 field IMRT ~ 15 minutes Rapid Arc (2 or 3 arc) ~ 3-6 minutes Tomotherapy ~ 12 minutes (1.0 cm Jaw setting) 6 minutes (2.5 cm Jaw setting) Average Daily Image Guidance 9 field IMRT ~ 5 minutes Rapid Arc (2 or 3 arc) ~ 5 minutes Tomotherapy ~ 3 minutes (Volume < 30 slices)

49 Head and Neck Comparison How is the best plan selected? Maximum Dose Conformality Homogeneity Target coverage OAR doses Trade-offs of each plan

50 How many letter F s do you see? FINISHED FILES ARE THE RESULT OF YEARS OF SCIENTIFIC STUDY COMBINED WITH THE EXPERIENCE OF YEARS

51 IV. Comparative Case Studies

52 Case #1: Unilateral HN 49 y.o. woman with T2N0 SCC of R oral tongue s/p hemiglossectomy and neck dissection 3 dose regions PTV 60 PTV 56 PTV 50 RTOG 0920 protocol

53 Case #1: Unilateral HN Dose Comparison (cgy) Static IMRT RapidArc Tomotherapy Max Dose 6945 (116%) 6631 (111%) 6549 (109%) Max Spinal Cord Mean L Parotid Mean R Parotid Max Mandible Mean L Cochlea Mean R Cochlea

54 Dose (cgy) Case #1: Unilateral Static IMRT RapidArc Tomotherapy Max Dose Max Spinal Cord Mean L Parotid Mean R Parotid Max Mandible Mean L Cochlea Mean R Cochlea Structure

55 Static IMRT Tomotherapy Rapid Arc

56 Case #2: Bilateral HN 69 y.o. male with T4N1M0 SCC of L BOT Concurrent cetuximab 3 dose regions PTV 70 PTV 63 PTV 56

57 Case #2: Bilateral HN Dose Comparison (cgy) Static IMRT RapidArc Tomotherapy Max Dose 7870 (112%) 7646 (109%) 7267 (104%) Max Spinal Cord Mean L Parotid Mean R Parotid Max Mandible Mean L Cochlea Mean R Cochlea

58 Dose (cgy) Case #2: Bilateral Static IMRT 4000 RapidArc Tomotherapy Max Dose Max Spinal Cord Mean L Parotid Mean R Parotid Max Mandible Mean L Cochlea Mean R Cochlea Structure

60 Case #3: Bilateral HN 61 y.o. male with T4N2c SCC of BOT Concurrent cisplatin 3 dose regions PTV 70 PTV 63 PTV 56

62 Dose (cgy) Case #3: Bilateral Static IMRT 4000 RapidArc Tomotherapy Max Dose Max Spinal Cord Mean L Parotid Mean R Parotid Max Mandible Mean L Cochlea Mean R Cochlea Structure

64 Case #4: Bilateral HN 49 y.o. male with T2aN1M0 pleomorphic rhabdomyosarcoma of the BOT Concurrent ifosfamide 2 dose regions PTV 67.5 PTV 60

66 Dose (cgy) Case #4: Bilateral Static IMRT RapidArc Tomotherapy Max Dose Max Spinal Cord Mean L Parotid Mean R Parotid Max Mandible Mean L Cochlea Mean R Cochlea Structure

68 General Conclusions NonTomo plans tend to run hotter overall Especially rapid arc Rapid Arc shares similarities to both IMRT and Tomotherapy depending on structure Middle child Tomotherapy contributes higher dose to cochlea and other structures above or below the PTV. Dynamic Jaw upgrade

69 General Conclusions Unilateral disease Better with static IMRT Sparing of contra lateral neck 7 field beam arrangement Bilateral disease Better with Tomotherapy Conformality Maximum dose lower Rapid Arc is a beautiful plan but often the maximum dose is too high.

70 Situations We ve Experienced Patient switching between machines Dose tracking VelocityAI Composite Plans Adaptive planning Maintain the same treatment machine for consistency.

71 In Conclusion First we began planning with static beam IMRT And it was good Next we added rapid arc planning and we had options And sometimes it was better Then we branched out and began Tomotherapy planning. Now we offer a well rounded option for the physician to evaluate and better treatment plans for our patients.

72 Acknowledgements Special thanks to Dr. John Holland for sharing insight concerning key aspects of head and neck cancer treatments. Reference material was obtained from the American Cancer Society and The National Cancer Institute.

73 Answer is 6. Not everything is apparent the first time through FINISHED FILES ARE THE RESULT OF YEARS OF SCIENTIFIC STUDY COMBINED WITH THE EXPERIENCE OF YEARS

74 Thank you