Anatomy-based Anatomy-based MLC Field Optimization MLC Field Optimization
for the Treatment of for the Treatment of Gynecologic MalignanciesGynecologic Malignancies
Myriam Bouchard M.D.Myriam Bouchard M.D.Nadeau S, Germain I, Raymond P.E., Nadeau S, Germain I, Raymond P.E., Harel F, Beaulieu F, Beaulieu L, Roy R, Harel F, Beaulieu F, Beaulieu L, Roy R, Gingras LGingras L
Dep. of radiation oncology of L’Hotel-Dieu de Quebec, Dep. of radiation oncology of L’Hotel-Dieu de Quebec, QC, Canada QC, Canada Dep. of Physics, Physics Engineering and Optics, Laval Dep. of Physics, Physics Engineering and Optics, Laval University, Quebec, CanadaUniversity, Quebec, Canada
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
IMRT for GYN IMRT for GYN malignanciesmalignancies
Mundt Mundt et alet al.(Chicago, 2000).(Chicago, 2000)Portelance Portelance et alet al.(St. Louis, 2001).(St. Louis, 2001)Heron Heron et alet al.(Pittsburgh, 2003).(Pittsburgh, 2003)Lujan Lujan et alet al.(Chicago, 2003).(Chicago, 2003)D’Souza D’Souza et alet al. (Houston, 2005). (Houston, 2005)
Adequate target coverageAdequate target coverageOARs sparingOARs sparing
Small bowelSmall bowel RectumRectum BladderBladder Bone marrowBone marrow
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
IMRT for GYN IMRT for GYN malignanciesmalignancies
Post-operativePost-operative whole-pelvis whole-pelvis radiotherapyradiotherapy– More bowel to spare, bowel replacing More bowel to spare, bowel replacing
uterusuterus– Less organ motionLess organ motion
Good clinical results with IMRT Good clinical results with IMRT 11 – 36 patients, whole-pelvis IMRT36 patients, whole-pelvis IMRT
Median follow-up = 19,6 monthMedian follow-up = 19,6 month
– 13.9% less GI-GII toxicity13.9% less GI-GII toxicity1 MUNDT et al. IJROBP, vol.56 #5 (2003) pp.1354-1360
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
IMRT for GYN IMRT for GYN malignanciesmalignancies
Disadvantages of IMRTDisadvantages of IMRT– Large number of segments and MULarge number of segments and MU
Increased scattered doseIncreased scattered dose Dose calculation uncertaintiesDose calculation uncertainties
– Higher potential impact of machine or Higher potential impact of machine or patient positioning errors patient positioning errors
– Increased planning, treatment and Increased planning, treatment and quality assurance timequality assurance time
– Higher impact of organ motionHigher impact of organ motion
BallistaBallistaA new inverse planning A new inverse planning
approachapproach
A dosimetric studyA dosimetric studyApproved by the local institutional committee for medical Approved by the local institutional committee for medical ethicsethics
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
ObjectivesObjectives EvaluateEvaluate Ballista Ballista as an alternative as an alternative
– Between 4-field and IMRTBetween 4-field and IMRT
– For post-operative whole-pelvis For post-operative whole-pelvis radiotherapy in gynecologic radiotherapy in gynecologic malignanciesmalignancies
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
HypothesisHypothesis Same target coverageSame target coverage
Organs at risk (OARs) sparingOrgans at risk (OARs) sparing– Better than 4-field Better than 4-field – As good as IMRT ?As good as IMRT ?
Treatment delivery advantagesTreatment delivery advantages
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
Materials and methodsMaterials and methods 10 patients10 patients
Endometrial or cervix malignanciesEndometrial or cervix malignancies
Post-operative external Post-operative external radiotherapyradiotherapy
45 Gy / 25 fractions, whole-pelvis45 Gy / 25 fractions, whole-pelvis
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
Materials and methodsMaterials and methods
For comparison purposes For comparison purposes
4 plans created for each patient4 plans created for each patient
Conventional 4-fieldConventional 4-field Enlarged 4-fieldEnlarged 4-field
– Results for OARs at same PTV Results for OARs at same PTV coveragecoverage
IMRTIMRT BallistaBallista
Inverse planning
Materials and Materials and methodsmethods
Forward planningForward planning
4-field4-field
enlarged 4-fieldenlarged 4-field
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
Materials and methodsMaterials and methods Planning CTscan as usualPlanning CTscan as usual
Conventional planning : Conventional planning : – 4-field plans based on bony landmarks4-field plans based on bony landmarks– Created before other plan conceptionCreated before other plan conception
Enlarged 4-fieldEnlarged 4-field– Aperture shaped to PTVAperture shaped to PTV
Materials and Materials and methodsmethods
Inverse planningInverse planning
IMRTIMRT
BallistaBallista
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
CTV (ITV)CTV (ITV) External iliac nodesExternal iliac nodes Internal iliac nodesInternal iliac nodes Obturator nodesObturator nodes Presacral regionPresacral region 1/2 superior vagina1/2 superior vagina ParametersParameters
Vessels + 5 mm
ITV 1 cm
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
OARsOARs Bowel (colon + small bowel)Bowel (colon + small bowel)
– Region at risk to find bowelRegion at risk to find bowel
= RAR-B= RAR-B RectumRectum BladderBladder Bone marrowBone marrow
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
IMRTIMRT Plans created with PinnaclePlans created with Pinnacle3 3
systemsystem Step-and-shootStep-and-shoot 7 coplanar and equidistant 6 MV 7 coplanar and equidistant 6 MV
beamsbeams– 1 extraction1 extraction– 10-12 intensity levels10-12 intensity levels– Minimum field area = 4 cmMinimum field area = 4 cm22
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
BallistaBallista 1 1
Inverse planning systemInverse planning system – Recently developed at L’Hotel-Dieu de Recently developed at L’Hotel-Dieu de
QcQc Simultaneous optimizationSimultaneous optimization
– Gantry, table and collimator anglesGantry, table and collimator angles– Wedge angle and beam weightsWedge angle and beam weights
Intensity modulationIntensity modulation– Anatomy-based MLC fieldsAnatomy-based MLC fields
1 BEAULIEU et al. Med.Phys.31, 1546-1557 (2004)
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
Anatomy-based fieldsAnatomy-based fields
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
• Number of fields• Gantry and table angle optimization
Feasibility
Selection of a fixed geometry (class solution)
Steps Result / conclusion
• Addition of sub- anatomic structures
New treatment that is comparable to IMRT
BallistaBallista
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
Beam orientation for Beam orientation for Ballista Ballista plansplans
9 beams
23 MV
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
• Number of fields• Gantry and table angle optimization
Feasibility
Selection of a fixed geometry (class solution)
Steps Result / conclusion
• Addition of sub- anatomic structures
New treatment that is comparable to IMRT
BallistaBallista
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
Sub-anatomic Sub-anatomic structuresstructures
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
AnalysisAnalysis
For each plan (4) created For each plan (4) created for each patient (10)for each patient (10)
DVH DVH – PTV and OARsPTV and OARs
Number of segmentsNumber of segments Number of MUNumber of MU
Statistics : Student’s paired Statistics : Student’s paired tt-test-test
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
PTV coverage / PTV coverage / homogeneityhomogeneity
4-field Enlarged4-field
IMRT Ballista
77%
p =0.03
(Mean±SEM, n=10)
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
RAR-B RAR-B 40 and 45 Gy40 and 45 Gy
+ 34.7 %
4-field Enlarged4-field
IMRT Ballista
(Mean±SEM, n=10)
For the same PTV coverage
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
RAR-BRAR-B
4-field Enlarged4-field
IMRT Ballista
+ 20.8 %
Ballista vs 4-field : V45 Gy, p < 0,001
(Mean±SEM, n=10)
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
RAR-BRAR-B
(Mean±SEM, n=10)
45 Gy : p = 0.15
40 Gy : p < 0.001 (diff. = 61.4 cm3 or 9.9% )
4-field Enlarged4-field
IMRT Ballista
(Mean±SEM, n=10)
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
Rectum – mean V 45 Rectum – mean V 45 GyGy
4-champs4-champs IMRTIMRT BallistaBallista p valuep value(difference)(difference)
61.7 %61.7 % 50.0%50.0% 59.9%59.9% NSNS(1.8%)(1.8%)
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
Rectum – mean V 45 Rectum – mean V 45 GyGy
4-champs4-champs IMRTIMRT BallistaBallista p valuep value(difference)(difference)
61.7 %61.7 % 50.0%50.0% 59.9%59.9% SSSS(9.9%)(9.9%)
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
Bladder – mean V 45 Bladder – mean V 45 GyGy
4-champs4-champs IMRTIMRT BallistaBallista p valuep value(difference)(difference)
91.3%91.3% 46.0%46.0% 47.8%47.8% SSSS(43.5%)(43.5%)
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
Bladder – mean V 45 Bladder – mean V 45 GyGy
4-champs4-champs IMRTIMRT BallistaBallista p valuep value(difference)(difference)
91.3%91.3% 46.0%46.0% 47.8%47.8% NSNS(1.8%)(1.8%)
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
OARs OARs V47.25 V47.25 GyGy
MeanMeanVV47.2547.25 GyGy
4-field4-field EnlargeEnlargedd
4-field4-field
IMRTIMRT BallistaBallista
RAR-BRAR-B 3.4%3.4% 1.6%1.6% 9.2%9.2% 6.7%6.7%
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
OARs OARs V47.25 V47.25 GyGy
MeanMeanVV47.2547.25 GyGy
4-field4-field EnlargeEnlarged 4-fd 4-f
IMRTIMRT BallistaBallista
RectumRectum 0.1%0.1% 5.6%5.6% 4.6%4.6% 7.3%7.3%
BladderBladder 1.4%1.4% 10.0%10.0% 20.3%20.3% 18.8%18.8%
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
Bone marrowBone marrowDoses moyennes - moelle osseuse
V40Gy; 27,8
V40Gy; 46,2
V40Gy; 32,5 V40Gy; 36,4
0,010,020,030,040,050,060,070,080,090,0
100,0
4-champs 4-champs élargi IMRT Ballista
Vo
lum
e (%
)
V10Gy
V20Gy
V30Gy
V40Gy
V45Gy
V47.25Gy
4-field Enlarged 4-field
IMRT Ballista(Mean±SEM, n=10)
Enlarged 4-field vs Ballista : V40 Gy, p < 0,001 (for the same PTV coverage)
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
V 50% and V 95%V 50% and V 95%
0
2000
4000
6000
8000
10000
12000
1
Vol
ume
(cc)
4-champs
4-champs élarg.
IMRT
Ballista
Volume traitéVolume irradiéIrradiated volume Treated volume
4-field
Enlarged 4-f
(Mean±SEM, n=10)
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
Number of segmentsNumber of segments
4-field4-field EnlargedEnlarged
4-field4-fieldIMRTIMRT BallistaBallista
44 44 128.6 ± 0.8 128.6 ± 0.8 33.3 ± 0.7 33.3 ± 0.7
(Mean±SEM, n=10)
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
Number of MUNumber of MUM
on
itor
Un
its
4-field
(Mean±SEM, n=10)
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
Calculated / delivered Calculated / delivered dosesdoses
Impact of leaf position errorsImpact of leaf position errors
± 1.4 Gy
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
Dose constraint on Dose constraint on OARsOARs
Priorities in our studyPriorities in our study First priority on RAR-BFirst priority on RAR-B Bladder Bladder
– Relative important weight given to it…Relative important weight given to it… Organ motion +++Organ motion +++ Eventually replaced by small bowelEventually replaced by small bowel
Bone marrow : when possibleBone marrow : when possible
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
OARs resultsOARs results Bone marrow resultsBone marrow results
– Worse compared to conventional Worse compared to conventional planningplanning but PTV coverage not optimalbut PTV coverage not optimal
– Similar gains IMRT vs BallistaSimilar gains IMRT vs Ballista
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
OARs resultsOARs results
To enhance sparing…To enhance sparing… Organ motion study necessary Organ motion study necessary 22
– To limit as possible expansion for PTVTo limit as possible expansion for PTV In our study, ITV/PTV limited sparing of In our study, ITV/PTV limited sparing of
rectum rectum
Optimal patient immobilizationOptimal patient immobilization– essentialessential
2 AHAMAD et al. (MDACC). IJROBP 62 (4) p.1117-1124 (2005)
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
Advantages Advantages BallistaBallista vs IMRTvs IMRT
Number of segments reduced by Number of segments reduced by 75%75%
Number of MU reduced by 55%Number of MU reduced by 55%
Result in scattered radiation– risk of second malignancies
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
Advantages Advantages BallistaBallista vs IMRTvs IMRT
Dose calculation + precise and + Dose calculation + precise and + robustrobust
treatment time treatment time (door-to-door)(door-to-door)
– 40-45 min IMRT – 20-25 min Ballista
quality assurance timequality assurance time– Dosimetric QA measurements can be Dosimetric QA measurements can be
avoidedavoided Larger segmentsLarger segments
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
Class solutionClass solution Statistic analysis on each beam’s roleStatistic analysis on each beam’s role
– Frequency of utilization of beamFrequency of utilization of beam To spare a determined (part of) OARTo spare a determined (part of) OAR To irradiate a part of the PTVTo irradiate a part of the PTV
Class solution based on «beam’s role»Class solution based on «beam’s role»
Similar plans created without Similar plans created without BallistaBallista Similar planning with other system is possibleSimilar planning with other system is possible
ConclusionsConclusions
BallistaBallistaA new inverse planning approachA new inverse planning approach
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
Conclusions – Conclusions – BallistaBallista PTV coverage improvedPTV coverage improved
OARs sparingOARs sparing– Similar to IMRT planningSimilar to IMRT planning– Except for the rectum,Except for the rectum, not as good as not as good as
IMRTIMRT Similar to conventional 4-fieldSimilar to conventional 4-field Under tolerance dosesUnder tolerance doses
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
Conclusions – Conclusions – BallistaBallista Advantages Advantages BallistaBallista vs IMRT vs IMRT
– Better dose calculation Better dose calculation – Less treatment timeLess treatment time– Less scattered doseLess scattered dose– Less quality assurance timeLess quality assurance time
Myriam Bouchard M.D.Myriam Bouchard M.D.ASTRO 2005ASTRO 2005
PerspectivesPerspectives Clinical results to comeClinical results to come
– Feasibility studyFeasibility study– 15 patients treated 15 patients treated
whole-pelvis after resection of gynecologic whole-pelvis after resection of gynecologic malignanciesmalignancies