Gregoire H&N

Conformal radiotherapy and IMRTConformal radiotherapy and IMRTin Head and Neck Tumorsin Head and Neck Tumors

The “academic” view point

The “academic” view point

ICRU report 62, 1999

• Gross Tumor Volume: GTV

• Clinical Target Volume: CTV

• Planning Target Volume: PTV

Target volumes in Radiation Target volumes in Radiation OncologyOncology::ICRU ICRU definitiondefinition

ll 15 head & neck tumors15 head & neck tumorsll 15 brain tumors15 brain tumorsll 3 different masks (3, 4 & 5 FP) 3 different masks (3, 4 & 5 FP) ll 3 fictitious 3 fictitious isocentersisocenters

Immobilization of Immobilization of Head & Neck patientsHead & Neck patients

ll 915 portals images acquired.915 portals images acquired.ll 98 %98 % analysedanalysed..

ll Total Displacement.Total Displacement.uu SIM SIM -- EPIDEPIDii

ll Systematic Displacement.Systematic Displacement.uu M(SIM M(SIM -- EPIDEPIDii))

ll Random Displacement.Random Displacement.uu (SIM (SIM -- EPIDEPIDii) ) -- [ M(SIM [ M(SIM --

EPIDEPIDii)])]

ll IntraobserverIntraobserver variation:variation:0.7 mm (10.7 mm (1 SdSd).).

Immobilization of Head & Neck patientsImmobilization of Head & Neck patients

0.00.10.20.30.40.50.60.70.80.91.0

0 1 2 3 4 5 6 7 8 9 10Deviation from the isocenter (mm)

Cum

ulat

ive

inci

denc

eHead

(3-5 FP) Total 3Total 3--DDdeviationsdeviations

0.00.10.20.30.40.50.60.70.80.91.0

0 1 2 3 4 5 6 7 8 9 10Deviation from the isocenter (mm)

Cum

ulat

ive

inci

denc

e

Neck(3-5 FP)

00.10.20.30.40.50.60.70.80.9

1

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14Deviation of the isocenter (mm)

Cum

ulat

ive

inci

denc

e Shoulder(4 & 5 FP)

Characteristics of currentCharacteristics of currentimaging modalitiesimaging modalities

CT MRI PET fMRIImage characteristics

skin contour + ± ± -soft-tissue contrast ± + - -bone contrast + ± - -air contrast + ± ± -metallic artefacts + ± - ±movement artefacts - + ± +

Machine characteristicslarge “tunnel” size + - - -distortion - + ± +electron density + - ± -multiplannar imaging - + ± +

Image acquisitionImage acquisition


• Dual detector spiral CT

• 2.7 mm collimation, pitch 0.7, reconstruction of 2 - 2.5 mm

• Display matrix of 512 x 512 pixels

• Contrast enhancement (interstitial and blood vessel contrast)

Conformal radiotherapy:reference coordinates

Conformal radiotherapy:3D reconstruction

Conformal radiotherapy:image display

Cervical lymph node groups(MSKCC classification)

Adopted by the Academy’s Committee for Head & Neck Surgery and Oncology

Robbins et al, 1991

The The presentpresent … … which which CTV for the neck ?CTV for the neck ?

State of the art

• Predictive pattern of lymph node involvement in HNSCC

• Selective neck treatment (irradiation or dissection) for selected N stage


Definition of the extend of the CTV in the neck

IIIV

III

Ia

Ib

II

Ia

Ib

The present …CT-based delineation oflymph node levels in the neck

Grégoire et al., 2000

Ia

Ib

II

RP

VI

VIII

Conformal radiotherapy:volume delineation

Conformal radiotherapy:Beam selection

Conformal radiotherapy:Dose distribution

Conformal radiotherapy:Dose volume histogram


Mr H. D. (77 years): T3-N0-M0 base of tongue (ICD0-10: C01)


Mr H. D. (77 years): T3-N0-M0 base of tongue (ICD0-10: C01)

Target volumesTarget volumes• T: CTV1: GTV + 1.5 cm margin

CTV2: GTV + 0.5 cm marginPTV1&2 : CTV + 4 mm

• N:CTV: R & L LII - IVPTV: CTV + 4 mm

Dose prescriptionDose prescription• T: PTV1: 50 Gy, 25x2 Gy

PTV2: 70 Gy, 35x2 Gy• N:PTV: 50 Gy, 25x 2Gy


Rx 6 MV40 Gy

Rx 6 MV30 Gy

Rx 6 MV50 Gy

Elect 8 MeV10 Gy

“Antique”(7 fields)


Dose (Dose (GyGy) at various organs at risk) at various organs at riskAntique Middle-age Art nouveau

PTV 55 GyDmean 63.2 60.1 59.2Dmax 79,1 76.6 74.6Dmin 10.0 39.1 44.4SD 10.2 9.5 8.1

PTV 70 GyDmean 72.4 71.7 70.6Dmax 76.9 76.5 74.6Dmin 67.4 65.2 67.0SD 1.8 2.1 1.5

L parotidDmedian 68.7 52.1 50.7Dmax 72.8 72.5 71.8Dmin 46.4 8.4 5.4SD 7.6 12.2 15.5

R parotidDmedian 69.6 65.7 40.6Dmax 72.9 72.6 55.9Dmin 62.1 4.4 3.6SD 1.7 24.9 16.7



Spinal cordDmean 22.8 19.6 22.7Dmax 43.0 41.9 47.6Dmin 5.5 3.3 2,7SD 16.0 16.1 18.0

MandibulaDmedian 71.5 68.9 60.5Dmax 76.8 74.5 72.2Dmin 51.1 4.8 3.7SD 2.2 22.0 17.4

Internal contourDmedian 41.6 13.6 19.3Dmax 79.2 76.6 74.6Dmin 2.0 1.2 1.1SD 21.5 23.4 22.2


“Middle Age”(9 fields)

Rx 6 MV40 Gy

Rx 6 MV20 Gy

Rx 6 MV50 Gy

Rx 6 MV10 Gy

Elect 8 MeV10 Gy


Rx 6 MV 50 Gy

“Art nouveau” (10 fields, 12 segments )

Ant.RPO LPO

SRAO SLAO

…

Post. Seg. 1 Post. Seg. 2


Rx 6 MV 20 Gy

“Art nouveau” (11 fields, 12 segments )

Ant. RAO LPO

LAO1 LAO2


Forward planning IMRT

• « human optimization »

Inverse planning IMRT

• Dose-volume constraints & weights for PTV and OARs

• optimization algorithms

• Penalty function

ll Spare cordSpare cordll Spare left parotid Spare left parotid ll 15 segments15 segmentsll 10 levels10 levels

1 6.Cummulative % of MUsSegment #

Courtesy of C. Field

Inverse planning IMRT for Inverse planning IMRT for Head and Neck TumorsHead and Neck Tumors

Inverse planning IMRT for Inverse planning IMRT for Head and Neck TumorsHead and Neck Tumors

PTV

Spared parotid gland

Courtesy of C. Field

Parotid Parotid gland gland functionfunction

lemonjuice

370 MBq 99mTc-pertechnetate

Parotid Parotid gland gland functionfunctionObjective assessment

0

10

20

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50

60

70

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100

0 10 20 30 40 50 60 70

Bilateral irradiationUnilateral irradiation

R= 0,77M

axim

um s

ecre

tion

(%)

Mean parotid dose (Gy)


Duration of treatment planning procedure

2D planning Forward planning Inverse planning(St-Luc) (Edmonton Cancer center)

Volume delineation 0 - 0.25h 2 - 3h 1 - 1.5h

Planning 0.25h 2 - 8h 1 - 2h

Individualized QC 0h 0.25h 1h

Treatment (per session) 10 - 15 min 20 - 25 min 15 min

State of the art

• Predictive pattern of lymph node involvement in HNSCC

• Selective neck treatment (irradiation or dissection) for selected N stage


Definition of the extend of the CTV in the neck

Gregoire H&N

Health & Medicine

Transcript of Gregoire H&N