IMRT/VMAT IMRT/VMAT withwith MC Dose MC Dose CalculationCalculation

Frank Lohr, M.D.University Medical Center MannheimGermany

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Disclosure

Cost of Travel provided for by Elekta

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Most important indications and treatment philosophy1. Head and Neck Cancer

CNS

Paranasal Sinus Tumors / Integrated Boost(Better Tumor coverage and shortening of overall treatment time)

NPC and other ENT Tumors(Parotid sparing when possible, better tumor coverage for NPC)

2. Prostate / Integrated boost (Potentially hypofractionation)

3. Gastric cancer(Better kidney sparing while treating the whole of the target)

4. Breast Cancer

5. Lung Cancer

6. Metastases

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Nutting et al., Lancet Oncol, 2011

„Unexpectedly, acutefatigue was greater in patients treated with IMRT, which could be due to thegreater radiation dose to non-tumour tissues. In an unplanned dosimetryreview in a subset of patients, mean radiationdoses to the posteriorfossa were 20–30 Gy in thepatients treated with IMRT compared with about 6 Gy in patients treated withconventional RT“

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Parotid Tolerance -> The (almost) definitive data….

Deasy/Eisbruch, IJROBP, 2010Dijkema/Eisbruch, IJROBP, 2010

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10J post full neck IMRT

Paranasal SinusIntegrated Boost

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NoDry Eye Syndrom

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3. Gastric Cancer as an example of a Large Abdominal Target

Tumor Localizations

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Right Kidney (Gy) Left Kidney (Gy)

Median Mean D30 D60 Cranial part

Middle part

Caudal part Median Mean D30 D60 Cranial

partMiddle part

Caudal part

3DCRT-1 2.52 3.18 3.3 2.4 5 <5 <5 41.07 36.9 46.3 38.4 47.8 45.3 25.2

3DCRT-2 3.2 7.76 8.1 2.7 22.5 4.5 <4.5 25.8 22.95 27 18 45 42.7 36

IMRT-1 1.49 1.61 1.77 1.39 11 5 0 20.25 22.18 26.68 18.15 29 26 9

IMRT-2 14.77 16.12 17.4 13.8 13 8 4 23.84 23.28 27.7 21.2 26.8 18.5 13.5

3DCRT IMRT

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OS DFS

5-FU only

Boda-Heggemann et al., IJROBP, 2009

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T2w: (A) IMRT vs. (B) 3D

A B

4. Breast Cancer

Tumor Localizations

Optimization of Tangent IrradiationAbo Madyan et al., Strahlentherapie, 2007

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Breast IMRT reduces Maximum dose to the heart at the expense of higher low dose exposure and a higher dose to the contralateral breast

El Haddad/Lohr et al., IJROBP, 2008

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Distribution of Coronary Artery Stenosis After Radiation forBreast Cancer

Nilsson, JCO, 2012

Tumor Localizations

5. Lung Cancer

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3. Image Guided Radiotherapy Treatmentwith Cone-Beam-CT at Linac

1. CTV-Definition/Minimimizationbased on functional Imaging (PET-CT)

Image Guided, PET-assisted Radiotherapy of Lung CancerTarget Volume Reduction and RT-Optimization for critical Tumor-to-Lung Ratio

2. Treatment Planning as IMRT based on Monte-Carlo Dose calculation

Suboptimal Positioning

Optimal Positioning

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Measurement setup

IBA Matrixx EvolutionIBA MulticubeCIRS dynamic platformmodel 008PL (accuracy0.05mm)

VMAT plan generated in Monaco 2.0.3.beta

Fleckenstein et al., submitted

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A=10mm, T=3.6s, cos4-motion trajectory

static case with motion difference map

Fleckenstein et al., submitted

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Monaco® 201: Leveraging the experience of more than

1000 Monaco with VMAT patients

Frank Lohr, Jens FleckensteinUniversity Medicine Mannheim, Germany

Oct. 1st, 201120th Elekta User Meeting

Miami, USA

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LINAC 1 Elekta PreciseX 6,18; e, MLC,EPID

LINAC 2 Siemens MevatronX 6,23; e, MLC, EPID

LINAC 3 Elekta SynergyX 6; e, MLC,EPID,cone beamIntegrity

LINAC 4 Elekta SynergyX 6; e, MLC,EPID, cone beam, Integrity

5 x Elekta Monaco 3.2 Monte-Carlo Systems

Elekta ABAS Atlas based autosegmentation

Philips Brilliance Big BoreCT-Simulation

Philips ElevaPCR System

ELEKTA MOSAIQ Vers. 2.4

LINAC 5 Elekta SynergyX 6; e, MLC, EPID

6 x NucletronMasterplan vers. 4.0

MOSAIQ

90 clients

Connection to satellite 2 in a distance of 30 kmConnectio to satellite 2

Start Nov.2011Distance 1 km

Intraaoperative unit

Zeiss Intrabeam, 50 KV

Replacement 2011/12- x 6,10,18-160 leaf MLC- FFF- machine

Our Patient Mix for VMAT

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treatment plans by entities/modalities

560 samples Oct 2010-May 2011

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QA for VMAT

• So far • Extended Linac QA according DIN 6847-5• Full patient plan verification using EDR2/Gafchromic film and ion chambers• In vivo dosimetry during patient delivery for prostate cancer

• Recent additions:• IBA MatriXX 2D-arry detector for patient plan verification

• MatriXX Evolution with gantry angle sensorand multicube phantom(Comparison of measurement to TPS)

• MatriXX Evolution with gantry holder and Compass software (independent TPS usingmeasured fluences)

• IBA Compass

IBA Multicube

IBA transmision detector

IBA Compass

Boggula et al, submitted

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VMAT specific linac QA

Matrixx

test 1: gantry accuracy360°arc – open field (24 cm x 24 cm)test 2: field sizes, MLC dynamic„slide and pause“ MLC motion (2 cm x 20 cm)

J. L. BEDFORD and A. WARRINGTON “Commissioning of Volumetric Modulated Arc Therapy (VMAT)” Int. J. Radiation Oncology Biol. Phys., Vol. 73, No. 2, pp. 537–545, 2009.

Iview

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off-axis-target testtest 3: MLC and Gantrysynchronization

modulated VMAT arc, which deliversdose to a PTV 8 cm from isocenter(16 cm x 1 cm field)

interrupt

terminate

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irregular MLC shaped field

measurement setupGamma map (3%,3mm)film measurement

σMonaco = 0.5 %, σGeant4 = 1.3 % on a 2 mm dose gridγ(3 %, 3 mm) in the ROI10 :•97.3 % for film measurement against Monaco•99.0 % for film measurement against Geant4 and•99.4 % Monaco against Geant4•

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irregular MLC shaped field

profiles with initial Monaco ® head model

profiles with adjusted Monaco ® head model

Fleckenstein et al., submitted

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Dose to water – dose to medium conversion

film measurement setup CT-slice

Monaco dose slice global gamma (3%,3mm)

dm-dw corrected gamma (3%,3mm)

Fleckenstein et al., submitted

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Fleckenstein et al., submitted

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Monaco ® vs. Geant4patient with metallic implants

mean deviation of the organs at risk: (0.7± 0.3) % of D50(PTV)σMonaco= 0.4 %, σGeant4= 1.6 %

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Lung Tumor boost

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Breast will in a bit be exclusively tangential IMRT

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Cutaneous Melanoma Metastases

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VMAT for Reirradiation of Paraspinal Tumors

Stieler et al. submitted

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Gastric Cancer

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Koeck et al., IJROBP, 2012

Hodgkin‘s Disease

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Anal Cancer

640 MUBOT 8 min

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VMAT

562 MU/1.5 Gy

T~ 3 min 30 secIn June 2010 (already tested on our hardware)

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Step-and-Shoot IMRT

695 MU/1.5 Gy92 SegmentsT= 13 min

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Static Gantry IMRT VMAT

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VMAT vs. IMRT treatment plan comparison

convex PTV shapes tend to yield similar treatment quality in less time

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VMAT Customer Perspective

and

Schmid et al., Radiother Oncol, 2012

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Divide Treatment times by >2 for

- Agility MLC (aka „The Onesixty“) - plus Monaco 3.2

(Now on sale at an Elekta Dealer near you)

Well, rather FOR sale, certainly not ON sale……..

Problems

2. Secondary Tumors

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Secondary Tumors

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Secondary Sarcoma (Sarcomas arise inHigh Dose Volume-> no large difference betweenconventional 3D-RT and IMRT)

Secondary Carcinoma (Carcinomas arise inLow Dose Volume, this islarger for IMRT than forconventional 3D-RT)

Secondary Tumors

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Secondary Carcinoma is not a relevant problem for old patients

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SecondaryCarcinomais not a relevant problem whenpatients with a bad prognosis (such as itis the case withadvanced gastriccancer) are treated. Achieving cure is theproblem for thesepatients.

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Head and Neck:Irradiation of (more or less) thewhole neck circumference withtherapeutic doses (volume verysimilar to conventional 3D [paradigms changing slowly])->similar risk for secondarytumors for IMRT and 3D in theNeck area, probably slightlyelevated risk outside neck dueto elevated MU, increasedscatter. High risk for secondary, non RT-induced cancer, though(Lung!!)

Secondary Tumors: H&NRisk is not different from 3D if the whole diameter is irradiated

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1 Gy (blue), 5 Gy (green), 45 Gy (yellow) and 70 Gy (red)

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Low Doses areevil…….are they???

Slanina et al., Strahlentherapie, 1999

Hall, IJROBP, 2006

Secondary Tumors

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Pediatric Oncology is a problem…but not a disastrous oneThe St. Jude Data….Conventional RT Techniques!!!!!

Hijiya, JAMA, 2007

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But: Threshold energy forneutron generation is 6-8 MV,thus relevant only at >10MV

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Increase of the risk for secondary tumors of appr. 1% forconventional RT by 0.5% because of larger low-dose-volume and by another 0.25% by scatter/leakage

Risk of 2ndary tumors after IMRT < 1.75% (vs. 1% bei 3D-CRT)

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Mediastinal Tumors: Hodgkin‘s DiseaseElevated median but reduced mean breast dose as a result of improved heartprotection -> Consequences???

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Problems with Modelling

“The mean estimated ERR for breast, lung and thyroid were significantly (p < 0.01) lower with INRT than with IFRT planning, regardless of the radiation technique delivery used, assuming a linear dose-risk relationship. An ERR increase was however observed with the non-linear model. With the latter, mean ERR were significantly (p < 0.01) increased with IMRT or RA when compared to 3DCRT planning for the breast, lung and thyroid using an IFRT paradigm. After INRT planning, IMRT or RA increased the risk of RIC for lung and thyroid only. “

Weber et al., IJROBP, 2011

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Breast:Increase of mean and median contralateral breast dose verymoderate (from 1.5 to 2.5 Gy) while improved heart protectioncan be achieved(Example: 23 Segments - 7 Beams - 362 MUs)

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Wherethereal dangerlurks……

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Where the real danger lurks……

Cancer, 2012

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A Sneak Preview at MONACO 3.2

Courtesy M. Alber/F. Stieler