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Aperture-based IMRT for Aperture-based IMRT for GYN malignanciesGYN malignancies
Myriam Bouchard Myriam Bouchard S. Nadeau , I. Germain, P.-É. S. Nadeau , I. Germain, P.-É.
Raymond, F. Harel, F. Beaulieu, L. Raymond, F. Harel, F. Beaulieu, L. Beaulieu, R. Roy, L. GingrasBeaulieu, R. Roy, L. Gingras
Department of radiation oncology of Department of radiation oncology of
L’Hotel-Dieu de Quebec, QC, CanadaL’Hotel-Dieu de Quebec, QC, Canada
Results from the dosimetric study – 2005/2006
ObjectivesObjectives Contours definitionContours definition
– TargetTarget– Organs at riskOrgans at risk
Aperture-based vs Beamlet-based Aperture-based vs Beamlet-based IMRTIMRT
Gains vs Uncertainties in IMRT for Gains vs Uncertainties in IMRT for GYNGYN
Selected casesSelected casesEndometrial / Uterus cervix cancerEndometrial / Uterus cervix cancer
Post-operative EBRTPost-operative EBRT
= = Local Control benefitLocal Control benefit
PORTEC, Creutzberg et al. Lancet (2000) (endometrium)PORTEC, Creutzberg et al. Lancet (2000) (endometrium)GOG-99 (endometrium)GOG-99 (endometrium)Sedlis Sedlis Gyn Oncology (1999) (cervix)Gyn Oncology (1999) (cervix)
Purpose of txPurpose of tx
No survival benefit, attempt to reduce side effects from adjuvant
treatments
What do we treat?What do we treat?
GYN postop EBRTGYN postop EBRT
CTVCTV External iliac nodesExternal iliac nodes Internal iliac nodesInternal iliac nodes Obturator nodesObturator nodes Presacral regionPresacral region 1/2 superior of vagina1/2 superior of vagina ParametersParameters
ControversiesControversies
CTVCTV
Controversies -- CTVControversies -- CTV Endometrium CTV Endometrium CTV ÞÞ Cervix CTV Cervix CTV
– Presacral regionPresacral region
Presacral CTV / 4-fieldPresacral CTV / 4-field
CTV95% Isodose
Controversies -- CTVControversies -- CTV Endometrium CTV Endometrium CTV ÞÞ Cervix CTV Cervix CTV
– Presacral regionPresacral region Upper limit ?Upper limit ?
– L5-S1, L4-L5… (common iliac LN)L5-S1, L4-L5… (common iliac LN) External iliac limitExternal iliac limit
Ant limit / Ext. Iliac LNAnt limit / Ext. Iliac LN
Controversies -- CTVControversies -- CTV Endometrium CTV Endometrium CTV ÞÞ Cervix CTV Cervix CTV
– Presacral regionPresacral region Upper limit ?Upper limit ?
– L5-S1, L4-L5… (common iliac LN)L5-S1, L4-L5… (common iliac LN) External iliac limitExternal iliac limit Margin around vesselsMargin around vessels
– How big?How big?
Pelvic LN mapping Pelvic LN mapping literatureliterature
Taylor Taylor et alet al 20 patients, GYN malignancies20 patients, GYN malignancies
MRI + iron oxyde particlesMRI + iron oxyde particles
CTV = CTV = – margins 3-5-7-10-15 mmmargins 3-5-7-10-15 mm– PTV = CTV + 1 cmPTV = CTV + 1 cm
Taylor Taylor et alet al
CTV CTV MarginsMargins
N coverageN coverage Bowel Bowel inside PTVinside PTV
5 mm5 mm 76%76% ------
7 mm7 mm 88%88% 146,9 cc146,9 cc
10 mm10 mm 94%94% 190 cc190 cc
15 mm15 mm 99%99% 266 cc266 cc
Taylor et al
99% coverage modified-7 mm99% coverage modified-7 mm
18 patients with prostate cancer N+18 patients with prostate cancer N+ Margin 2 cm around vessels (includes PTV)Margin 2 cm around vessels (includes PTV) 94,5 % N coverage94,5 % N coverage
Controversies -- CTVControversies -- CTV Endometrium CTV Endometrium CTV ÞÞ Cervix CTV Cervix CTV
– Presacral regionPresacral region Upper limit ?Upper limit ?
– L5-S1, L4-L5… (common iliac LN)L5-S1, L4-L5… (common iliac LN) External iliac limitExternal iliac limit Margin around vesselsMargin around vessels
– How big?How big? ITV… bladder fillingITV… bladder filling
– MDACC = fusion pre-postmictional MDACC = fusion pre-postmictional CTsimCTsim
ITV 1 cmITV 1 cm
CTV – CTV – ourour initial choices*initial choices*
External iliac nodesExternal iliac nodes Internal iliac nodesInternal iliac nodes Obturator nodesObturator nodes Presacral regionPresacral region 1/2 superior of vagina1/2 superior of vagina ParametersParameters
+ 5 mm around vessels
ITV 1 cm
*Before RTOG 0418, Shih et al. and Taylor et al. publications
3D CTV3D CTV
PTV = CTV + 1 cmPTV = CTV + 1 cm
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
Bowel / RAR-BBowel / RAR-B
Why IMRT for GYN ?Why IMRT for GYN ?
Inadequate coverageInadequate coverage
PTVPTV
Conventional 4-Conventional 4-fieldsfields
95% Isodose
Inadequate coverageInadequate coverage Greer et al. (1990)Greer et al. (1990)
S2-3 post limit : S2-3 post limit : 49% inadequate49% inadequate coverage coverage 87% com. il. bifurcation above L5-S187% com. il. bifurcation above L5-S1
Bonin et al. / Pendelbury et al. Bonin et al. / Pendelbury et al. (1993) (1993)
45% / 62% inadequate coverage45% / 62% inadequate coverage ext. il LN ext. il LN
Finlay et al. (2006)Finlay et al. (2006) 95,4% at least 1 inadequate margin with bony 95,4% at least 1 inadequate margin with bony
landmarkslandmarks
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
IMRT for GYN IMRT for GYN malignanciesmalignancies
Good clinical results with IMRT Good clinical results with IMRT 11 – 36 patients, whole-pelvis IMRT36 patients, whole-pelvis IMRT
Median FU = 19,6 monthMedian FU = 19,6 month
– 13.9% less GI-GII toxicity13.9% less GI-GII toxicity
– 3 year3 year Pelvic LC Pelvic LC 87,5%87,5% * (62 patients) * (62 patients) Cervix cancerCervix cancer 71% intact uterus71% intact uterus
1 Mundt et al. IJROBP, vol.56 #5 (2003) pp.1354-1360* Kochanski et al. ASTRO 2005 Abst #1114
Disadvantages of IMRTDisadvantages of IMRT Target volume definition Target volume definition
controversiescontroversies Impact ofImpact of
– Machine errors (MLC)Machine errors (MLC)– Patient positioning errors Patient positioning errors
Disadvantages of IMRTDisadvantages of IMRT Large # of segments and MULarge # of segments and MU
– Scattered doseScattered dose– Calculation uncertaintiesCalculation uncertainties
Time consumingTime consuming– PlanningPlanning– Treatment Treatment – Quality assuranceQuality assurance
Can we improve treatment Can we improve treatment delivery issues?delivery issues?
Ballista = Ballista = Aperture-based IMRTAperture-based IMRT
A feasability studyA feasability study- dosimetric- dosimetric- clinic- clinic
Let’s talk about IMRTLet’s talk about IMRT
Beamlet-basedBeamlet-based
vsvs
Aperture-basedAperture-based
Types of planningTypes of planning
Forward planningForward planning(conventional)(conventional)
– Manual (human) Manual (human) field definitionfield definition
– Followed by Followed by calculationcalculation
Inverse planning Inverse planning (IMRT)(IMRT)
– Dose objectives in Dose objectives in specific areas specific areas (contours)(contours)
– Solution found by Solution found by computer-assisted computer-assisted calculationcalculation
IMRTIMRT
Intensity Modulated Intensity Modulated
Radiation TherapyRadiation Therapy
Dose intensity varies inside the Dose intensity varies inside the beambeam– Several sub-fields (segments)Several sub-fields (segments)– Inverse planningInverse planning
No
Yes
Final plan
Does the plan meetthe clinical objectives?
Segmentation
Optimization of beamintensity profiles
Field geometry Basic objectives
Beamlet-based
IMRT
2nd
1st
*** Calculation steps
Aperture-based IMRTAperture-based IMRT
BallistaBallista 1 1
Inverse planning systemInverse planning system – Recently developed at L’Hotel-Dieu de Recently developed at L’Hotel-Dieu de
QcQc Intensity modulationIntensity modulation
– Anatomy-based MLC fieldAnatomy-based MLC field Simultaneous optimizationSimultaneous optimization
– Gantry, table and collimator anglesGantry, table and collimator angles– Wedge angle and beam weightsWedge angle and beam weights
1 BEAULIEU et al. Med.Phys.31, 1546-1557 (2004)
Aperture-basedSegmentation
Basic objectives Field geometry
Ballista
Anatomy-based fieldsAnatomy-based fields
Field weightsoptimization
Aperture-basedSegmentation
Basic objectives Field geometry
Ballista
Yes
Final plan
Does the plan meetthe clinical objectives?
No
Minor leafcorrections
Only
1
*** Calculation steps
X
Dosimetric studyDosimetric study
BallistaBallista for GYN for GYNPilot study -- Part IPilot study -- Part I
CHUQ -- Hotel-Dieu de Quebec CHUQ -- Hotel-Dieu de Quebec
Quebec cityQuebec city
Dosimetric objectivesDosimetric objectives 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
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
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+ brachy HDR boost+ brachy HDR boost
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
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
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
Beam orientation for Beam orientation for Ballista Ballista plansplans
9 beams
23 MV
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
ResultsResults
Target coverageTarget coverage
4-field Enlarged 4-field
IMRT Ballista
PTV coverage / PTV coverage / homogeneityhomogeneity
4-field Enlarged4-field
IMRT Ballista
77%
p =0.03
(Mean±SEM, n=10)
ResultsResults
OARs sparingOARs sparing
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
RAR-BRAR-B
4-field Enlarged4-field
IMRT Ballista
+ 20.8 %
Ballista vs 4-field : V45 Gy, p < 0,001
(Mean±SEM, n=10)
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)
ResultsResults
Treatment deliveryTreatment delivery
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)
Number of MUNumber of MUM
on
itor
Un
its
4-field
(Mean±SEM, n=10)
Calculated / delivered Calculated / delivered dosesdoses
Impact of leaf position errorsImpact of leaf position errors
± 1.4 Gy
DiscussionDiscussion
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– Concerns with 23 MV sec. neutrons…
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
IMRT for GYN IMRT for GYN malignanciesmalignancies
Post-operativePost-operative – More bowel to spareMore bowel to spare– Less organ motionLess organ motion
Main objective = Main objective = bowel sparingbowel sparing– Less bladder filling = more bowel to Less bladder filling = more bowel to
sparespare High sparing objectives on bladder tooHigh sparing objectives on bladder too
Movements vs shape of CTVMovements vs shape of CTV
Effect of AP-PA
rotation of the pelvis
Modified ImmobilizationModified Immobilization
Movements vs shape of CTVMovements vs shape of CTV
Effect of lateral
rotation
Less impact if spheric…
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)
ConclusionsConclusions
BallistaBallistaA new inverse planning approachA new inverse planning approach
Conclusions – Conclusions – BallistaBallista PTV coverage improvedPTV coverage improved
OARs sparingOARs sparing– Similar to IMRT planningSimilar to IMRT planning
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
Therapeutic ratio probably Therapeutic ratio probably improvedimproved
PerspectivesPerspectives Clinical results to comeClinical results to come 15 patients treated15 patients treated
– Acute toxicity analyzedAcute toxicity analyzed– Feasibility in a busy clinicFeasibility in a busy clinic
Anatomy-based Anatomy-based MLC Field Optimization MLC Field Optimization for the Treatment of for the Treatment of Gynecologic MalignanciesGynecologic Malignancies
Coauthors : Coauthors : Myriam Bouchard*Myriam Bouchard*Sylvain Nadeau*Sylvain Nadeau*Isabelle Germain* Isabelle Germain* Paul-Émile Raymond* Paul-Émile Raymond* François HarelFrançois HarelFrédéric Beaulieu** Frédéric Beaulieu** Luc Beaulieu*Luc Beaulieu*René Roy **René Roy **Luc Gingras**Luc Gingras**
ASTRO 2005ASTRO 2005AAPM 2005AAPM 2005CARO 2005CARO 2005COMP 2005COMP 2005SFRO 2005SFRO 2005AROQ 2005AROQ 2005
Questions : Questions : myriam.bouchard.1@ulaval.myriam.bouchard.1@ulaval.
caca
* Dep. of radiation oncology of L’Hotel-Dieu de Quebec, QC, * Dep. of radiation oncology of L’Hotel-Dieu de Quebec, QC, Canada Canada ** Dep. of Physics, Physics Engineering and Optics, Laval ** Dep. of Physics, Physics Engineering and Optics, Laval University, Quebec, CanadaUniversity, Quebec, Canada
ReferencesReferences Beaulieu Med.Phys. 31, 1546-1557
(2004) MundtMundt IJROBP 52 1330-1337 (200252 1330-1337 (2002)) Mundt Mundt IJROBP 56 1354-1360, (2003)56 1354-1360, (2003) Portelance Portelance IJROBP 51, 261-266 (200151, 261-266 (2001)) Ahamad (MDACC). IJROBP 62 (4) 1117-
24 (2005) Taylor IJROBP 63 (5) 1604- 12 (2005) Shih IJROBP 63 (4) 1262-69 (2005) Kochanski et al. ASTRO 2005 Abst #1114 Finlay Finlay IJROBP 64 (1) 205-09 (2006) 64 (1) 205-09 (2006)
AddendumAddendum
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)
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)
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%)
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%)
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%)
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%)
• 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
• 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
Sub-anatomic Sub-anatomic structuresstructures