1. Anatomy-based MLC Field Optimization for the Treatment of Gynecologic Malignancies Myriam Bouchard M.D. Nadeau S, Germain I, Raymond P.E., Harel F, Beaulieu F, Beaulieu L, Roy R, Gingras L Dep. of radiation oncology of L’Hotel-Dieu de Quebec, QC, Canada Dep. of Physics, Physics Engineering and Optics, Laval University, Quebec, Canada

2. ASTRO 2005 Myriam Bouchard M.D. IMRT for GYN malignancies Mundt et al.(Chicago, 2000) Portelance et al.(St. Louis, 2001) Heron et al.(Pittsburgh, 2003) Lujan et al.(Chicago, 2003) Mundt et al.(Chicago, 2000) Portelance et al.(St. Louis, 2001) Heron et al.(Pittsburgh, 2003) Lujan et al.(Chicago, 2003) D’Souza et al. (Houston, 2005) Adequate target coverage OARs sparing Small bowel Small bowel Rectum Rectum Bladder Bladder Bone marrow Bone marrow

3. ASTRO 2005 Myriam Bouchard M.D. IMRT for GYN malignancies Post-operative whole-pelvis radiotherapy Post-operative whole-pelvis radiotherapy –More bowel to spare, bowel replacing uterus –Less organ motion Good clinical results with IMRT 1 Good clinical results with IMRT 1 –36 patients, whole-pelvis IMRT Median follow-up = 19,6 month Median follow-up = 19,6 month –13.9% less GI-GII toxicity 1 MUNDT et al. IJROBP, vol.56 #5 (2003) pp.1354-1360

4. ASTRO 2005 Myriam Bouchard M.D. IMRT for GYN malignancies Disadvantages of IMRT Disadvantages of IMRT –Large number of segments and MU Increased scattered dose Increased scattered dose Dose calculation uncertainties Dose calculation uncertainties –Higher potential impact of machine or patient positioning errors –Increased planning, treatment and quality assurance time –Higher impact of organ motion

5. Ballista A new inverse planning approach A dosimetric study Approved by the local institutional committee for medical ethics

6. ASTRO 2005 Myriam Bouchard M.D. Objectives Evaluate Ballista as an alternative Evaluate Ballista as an alternative –Between 4-field and IMRT –For post-operative whole-pelvis radiotherapy in gynecologic malignancies

7. ASTRO 2005 Myriam Bouchard M.D. Hypothesis Same target coverage Same target coverage Organs at risk (OARs) sparing Organs at risk (OARs) sparing –Better than 4-field –As good as IMRT ? Treatment delivery advantages Treatment delivery advantages

8. ASTRO 2005 Myriam Bouchard M.D. Materials and methods 10 patients 10 patients Endometrial or cervix malignancies Endometrial or cervix malignancies Post-operative external radiotherapy Post-operative external radiotherapy 45 Gy / 25 fractions, whole-pelvis 45 Gy / 25 fractions, whole-pelvis

9. ASTRO 2005 Myriam Bouchard M.D. Materials and methods For comparison purposes 4 plans created for each patient Conventional 4-field Conventional 4-field Enlarged 4-field Enlarged 4-field –Results for OARs at same PTV coverage IMRT IMRT Ballista Ballista Inverse planning

10. Materials and methods Forward planning 4-field enlarged 4-field

11. ASTRO 2005 Myriam Bouchard M.D. Materials and methods Planning CTscan as usual Planning CTscan as usual Conventional planning : Conventional planning : –4-field plans based on bony landmarks –Created before other plan conception Enlarged 4-field Enlarged 4-field –Aperture shaped to PTV

12. Materials and methods Inverse planning IMRTBallista

13. ASTRO 2005 Myriam Bouchard M.D. CTV (ITV) External iliac nodes External iliac nodes Internal iliac nodes Internal iliac nodes Obturator nodes Obturator nodes Presacral region Presacral region 1/2 superior vagina 1/2 superior vagina Parameters Parameters Vessels + 5 mm ITV 1 cm

14. ASTRO 2005 Myriam Bouchard M.D. CTV / ITV

15. ASTRO 2005 Myriam Bouchard M.D. 3D CTV

16. ASTRO 2005 Myriam Bouchard M.D. PTV = CTV + 1 cm

17. ASTRO 2005 Myriam Bouchard M.D. OARs Bowel (colon + small bowel) Bowel (colon + small bowel) –Region at risk to find bowel = RAR-B Rectum Rectum Bladder Bladder Bone marrow Bone marrow

18. ASTRO 2005 Myriam Bouchard M.D. Bowel / RAR-B

19. ASTRO 2005 Myriam Bouchard M.D. IMRT Plans created with Pinnacle 3 system Plans created with Pinnacle 3 system Step-and-shoot Step-and-shoot 7 coplanar and equidistant 6 MV beams 7 coplanar and equidistant 6 MV beams –1 extraction –10-12 intensity levels –Minimum field area = 4 cm 2

20. ASTRO 2005 Myriam Bouchard M.D. Ballista 1 Inverse planning system Inverse planning system –Recently developed at L’Hotel-Dieu de Qc Simultaneous optimization Simultaneous optimization –Gantry, table and collimator angles –Wedge angle and beam weights Intensity modulation Intensity modulation –Anatomy-based MLC fields 1 BEAULIEU et al. Med.Phys.31, 1546-1557 (2004)

21. ASTRO 2005 Myriam Bouchard M.D. Anatomy-based fields

22. ASTRO 2005 Myriam Bouchard M.D. Number of fields Gantry and table angle optimization Feasibility Selection of a fixed geometry (class solution) StepsResult / conclusion Addition of sub- anatomic structures New treatment that is comparable to IMRT Ballista

23. ASTRO 2005 Myriam Bouchard M.D. Beam orientation for Ballista plans 9 beams 23 MV

24. ASTRO 2005 Myriam Bouchard M.D. Number of fields Gantry and table angle optimization Feasibility Selection of a fixed geometry (class solution) StepsResult / conclusion Addition of sub- anatomic structures New treatment that is comparable to IMRT Ballista

25. ASTRO 2005 Myriam Bouchard M.D. Sub-anatomic structures

26. ASTRO 2005 Myriam Bouchard M.D. Analysis For each plan (4) created for each patient (10) DVH DVH –PTV and OARs Number of segments Number of segments Number of MU Number of MU Statistics : Student’s paired t-test Statistics : Student’s paired t-test

27. Results Target coverage

28. ASTRO 2005 Myriam Bouchard M.D. 4-fieldEnlarged 4-field IMRTBallista

29. ASTRO 2005 Myriam Bouchard M.D. PTV coverage / homogeneity 4-field Enlarged 4-field IMRTBallista 77% p =0.03 (Mean±SEM, n=10)

30. Results OARs sparing

31. ASTRO 2005 Myriam Bouchard M.D. RAR-B 40 and 45 Gy + 34.7 % 4-field Enlarged 4-field IMRTBallista (Mean±SEM, n=10) For the same PTV coverage

32. ASTRO 2005 Myriam Bouchard M.D. RAR-B 4-field Enlarged 4-field IMRTBallista + 20.8 % Ballista vs 4-field : V45 Gy, p < 0,001 (Mean±SEM, n=10)

33. ASTRO 2005 Myriam Bouchard M.D. RAR-B (Mean±SEM, n=10) 45 Gy : p = 0.15 40 Gy : p < 0.001 (diff. = 61.4 cm 3 or 9.9% ) 4-field Enlarged 4-field IMRTBallista (Mean±SEM, n=10)

34. ASTRO 2005 Myriam Bouchard M.D. Rectum – mean V 45 Gy 4-champsIMRTBallista p value (difference) 61.7 % 50.0%59.9% NS (1.8%)

35. ASTRO 2005 Myriam Bouchard M.D. Rectum – mean V 45 Gy 4-champsIMRTBallista p value (difference) 61.7 % 50.0%59.9% SS (9.9%)

36. ASTRO 2005 Myriam Bouchard M.D. Bladder – mean V 45 Gy 4-champsIMRTBallista p value (difference) 91.3%46.0%47.8% SS (43.5%)

37. ASTRO 2005 Myriam Bouchard M.D. Bladder – mean V 45 Gy 4-champsIMRTBallista p value (difference) 91.3%46.0%47.8% NS (1.8%) NS (1.8%)

38. ASTRO 2005 Myriam Bouchard M.D. OARs V47.25 Gy Mean V 47.25 Gy 4-fieldEnlarged4-fieldIMRTBallista RAR-B3.4%1.6%9.2%6.7%

39. ASTRO 2005 Myriam Bouchard M.D. OARs V47.25 Gy Mean V 47.25 Gy 4-field Enlarged 4-f IMRTBallista Rectum0.1%5.6%4.6%7.3% Bladder1.4%10.0%20.3%18.8%

40. ASTRO 2005 Myriam Bouchard M.D. Bone marrow 4-field Enlarged 4-field IMRTBallista (Mean±SEM, n=10) Enlarged 4-field vs Ballista : V40 Gy, p < 0,001 (for the same PTV coverage )

41. ASTRO 2005 Myriam Bouchard M.D. V 50% and V 95% Volume traitéVolume irradié Irradiated volumeTreated volume 4-field Enlarged 4-f (Mean±SEM, n=10)

42. Results Treatment delivery

43. ASTRO 2005 Myriam Bouchard M.D. Number of segments 4-fieldEnlarged4-fieldIMRTBallista  4 4 4 4  4 4 4 4 128.6 ± 0.8 33.3 ± 0.7 (Mean±SEM, n=10)

44. ASTRO 2005 Myriam Bouchard M.D. Number of MU Monitor Units 4-field (Mean±SEM, n=10)

45. ASTRO 2005 Myriam Bouchard M.D. Calculated / delivered doses Impact of leaf position errors Impact of leaf position errors ± 1.4 Gy

46. Discussion

47. ASTRO 2005 Myriam Bouchard M.D. Dose constraint on OARs Priorities in our study First priority on RAR-B First priority on RAR-B Bladder Bladder –Relative important weight given to it… Organ motion +++ Organ motion +++ Eventually replaced by small bowel Eventually replaced by small bowel Bone marrow : when possible Bone marrow : when possible

48. ASTRO 2005 Myriam Bouchard M.D. OARs results Bone marrow results Bone marrow results –Worse compared to conventional planning but PTV coverage not optimal but PTV coverage not optimal –Similar gains IMRT vs Ballista

49. ASTRO 2005 Myriam Bouchard M.D. OARs results To enhance sparing… Organ motion study necessary 2 Organ motion study necessary 2 –To limit as possible expansion for PTV In our study, ITV/PTV limited sparing of rectum In our study, ITV/PTV limited sparing of rectum Optimal patient immobilization Optimal patient immobilization –essential 2 AHAMAD et al. (MDACC). IJROBP 62 (4) p.1117-1124 (2005)

50. ASTRO 2005 Myriam Bouchard M.D. Advantages Ballista vs IMRT Number of segments reduced by 75% Number of segments reduced by 75% Number of MU reduced by 55% Number of MU reduced by 55% Result in  scattered radiation – –  risk of second malignancies

51. ASTRO 2005 Myriam Bouchard M.D. Advantages Ballista vs IMRT Dose calculation + precise and + robust Dose calculation + precise and + robust  treatment time (door-to-door)  treatment time (door-to-door) – –40-45 min IMRT – –20-25 min Ballista  quality assurance time  quality assurance time –Dosimetric QA measurements can be avoided Larger segments Larger segments

52. ASTRO 2005 Myriam Bouchard M.D. Class solution Statistic analysis on each beam’s role Statistic analysis on each beam’s role –Frequency of utilization of beam To spare a determined (part of) OAR To spare a determined (part of) OAR To irradiate a part of the PTV To irradiate a part of the PTV  Class solution based on «beam’s role»  Similar plans created without Ballista Similar planning with other system is possible Similar planning with other system is possible

53. Conclusions Ballista A new inverse planning approach

54. ASTRO 2005 Myriam Bouchard M.D. Conclusions – Ballista PTV coverage improved PTV coverage improved OARs sparing OARs sparing –Similar to IMRT planning –Except for the rectum, not as good as IMRT Similar to conventional 4-field Similar to conventional 4-field Under tolerance doses Under tolerance doses

55. ASTRO 2005 Myriam Bouchard M.D. Conclusions – Ballista Advantages Ballista vs IMRT Advantages Ballista vs IMRT –Better dose calculation –Less treatment time –Less scattered dose –Less quality assurance time

56. ASTRO 2005 Myriam Bouchard M.D. Perspectives Clinical results to come Clinical results to come –Feasibility study –15 patients treated whole-pelvis after resection of gynecologic malignancies whole-pelvis after resection of gynecologic malignancies

57. Acknowledgments To Sylvain Nadeau, medical physicist to Radiation oncologists to Physicists to Physicists to Radiation therapists to Radiation therapists