Advances in craniospinal irradiationWilliam Parker Carolyn FreemanWilliam Parker Carolyn Freemanyy

CSF pathways

Conventional technique

VanDyk, 1977 IJROBPVanDyk, 1977 IJROBPa y , 9 J Oa y , 9 J O

Conventional technique

From KHAN, 1998

Evolution of CSI technique

Supine positionSupine position

CT simulationCT simulation

Simplification of beam geometrySimplification of beam geometry

Improvement in volume definition (CT & MR)Improvement in volume definition (CT & MR)

Better junction planning Better junction planning

Forward step and shoot IMRT for dose compensationForward step and shoot IMRT for dose compensation

Use of inverse IMRT for posterior fossa treatment Use of inverse IMRT for posterior fossa treatment

IMRT/Tomotherapy for CSI IMRT/Tomotherapy for CSI

Supine position

Patient comfortPatient comfortPatient comfortPatient comfort

Access to airwayAccess to airway

Standard accessoriesStandard accessories

Reproducible setupReproducible setup

Virtual Simulation and 3D CRTuse “modern” use “modern” linaclinac features to simplify techniquefeatures to simplify technique

t i j f j ti f th i d h lft i j f j ti f th i d h lfasymmetric jaws for junction feathering and easy halfasymmetric jaws for junction feathering and easy half--blockingblocking

isocentricisocentric setup to eliminate unnecessary setupsetup to eliminate unnecessary setupisocentricisocentric setup to eliminate unnecessary setup setup to eliminate unnecessary setup motionsmotions

Posterior field & CS junction

INF limit set with INF limit set with

20 cm20 cm1111oo

asymmetric jaw up to asymmetric jaw up to 20 cm20 cm

20 cm20 cm20 cm20 cm

“isocentric setup” “isocentric setup” -- couch motions in one direction onlycouch motions in one direction only

Whole brain field

Insufficient coverage of the whole brain and meninges in the treatment of medulloblastoma Insufficient coverage of the whole brain and meninges in the treatment of medulloblastoma

may correlate with increased risk of local failure.may correlate with increased risk of local failure. IJROBP 37(3) 523-9, 1997

Liu, Carrie, Parker, Freeman, Med Pediatr Oncol 38(1), 2002

Whole brain field

collimator rotationcollimator rotationcollimator rotation collimator rotation 1111oo to match to match diverging post diverging post

i fi ldi fi ld20 cm20 cm

spine fieldspine field

isocenterisocenter

half blocked with half blocked with asymmetric jawasymmetric jaw

Whole brain field

CTV = brain CTV = brain

PTV = brain+ 3mm PTV = brain+ 3mm

field edges are 7mm field edges are 7mm ggfrom PTVfrom PTV

blocking with MLCblocking with MLCblocking with MLCblocking with MLC

treat the brain forget treat the brain forget the lensesthe lensesthe lensesthe lenses

Posterior spine field

Simplified beam geometry

1111oo20 cm20 cm 30 cm30 cm

Anterior setup for posterior treatment

CS j nctionCS j nctionCS junctionCS junction

isocentersisocenters

gapgap

Better junction planning

1111oo20 cm20 cm 30 cm30 cm

40 cm40 cm 10 + x cm10 + x cm20 cm20 cm

Better junction planning

1111oo20 cm20 cm 30 cm30 cm

38 cm38 cm 11 + x cm11 + x cm21 cm21 cm

Better junction planning

1111oo20 cm20 cm 30 cm30 cm

36 cm36 cm 12 + x cm12 + x cm22 cm22 cm

Dose compensation with “IMRT”

No compensationNo compensation

S&S IMRTS&S IMRT

Dose compensation

90%90% 5%5% 5%5%

Posterior field dose compensation

Posterior fossa boost

IJROBP 41(3) 625-629, 1998 MRIMRI CTCT

Boost target definition

Inverse IMRT for CSI Multiple post fieldsMultiple post fields

Smaller targetSmaller target

S d t l dS d t l dSpread out low dose Spread out low dose conform high doseconform high dose

IMRT for CSI

Junction QA

Summary

supine position is more comfortable, reproducible, and supine position is more comfortable, reproducible, and allows airway accessallows airway access

CT, MR for improved volume definitionCT, MR for improved volume definition

virtual simulation with simplified geometry is safervirtual simulation with simplified geometry is safer

IMRT for dose compensationIMRT for dose compensation

inverse conformal IMRT with tomotherapy is viable andinverse conformal IMRT with tomotherapy is viable andinverse conformal IMRT with tomotherapy is viable and inverse conformal IMRT with tomotherapy is viable and safe treatment for CSIsafe treatment for CSI

ReferencesParker W Brodeur M, Roberge D, Freeman CR. Treatment of standard and non-standard craniospinal irradiation with helical tomotherapy Int J Radiat Oncol Biol Phys, in press 2009.

Parker W, Filion E, Roberge D, Freeman CR. Intensity-modulated radiotherapy for craniospinal irradiation: target volume considerations, dose constraints, and competing risks. Int J Radiat Oncol Biol Phys 2007;69:251-257

Parker WA Freeman CR A simple technique for craniospinal radiotherapy in the supine position Radiother Parker WA, Freeman CR. A simple technique for craniospinal radiotherapy in the supine position. Radiother Oncol 2006;78:217-222.

Liu M, Carrie C, Parker W, Freeman CR. Comparison of manual and computer-generated customized blocks for whole brain fields used in the treatment of medulloblastoma. Medical and Pediatric Oncology 2002; 38:55-57