quality and safety issues associated with proton beam therapy

Download Quality and Safety Issues Associated with Proton Beam Therapy

Post on 02-Jan-2017

213 views

Category:

Documents

0 download

Embed Size (px)

TRANSCRIPT

  • Indra J. Das, PhD, FACR, FASTRODepartment of Radiation Oncology

    Indiana University of School of Medicine, Indianapolis, &

    IU Health Proton Therapy CenterBloomington

    Quality and Safety

    Issues Associated with

    Proton Beam Therapy

  • Name Change (2011)

    Midwest Proton Radiotherapy Institute (MPRI)

    Indiana University Health Proton Therapy Center (IUHPTC)

    Same location, Same people, same machines

  • Safety & Quality Issues

    Machine (Cyclotron, Synchrotron)

    Beam line

    Bending magnets

    Energy Selector

    At production: synchrotron

    In beam line

    In Nozzle: range shifter

    Nozzle

    Treatment table

    Patient specific devices

  • 60-inch Cyclotron

    Radiation Lab in Berkeley

    Ernest LawrenceNobel Prize winner in Physics 1939

  • Types of Machines: Variable Design

    (Specific QA and Safety)

    Home grown (Cyclotron)

    Harvard Cyclotron

    Indiana university

    Loma Linda (only one of its kind): (Synchrotron)

    IBA (Cyclotron)

    Hitachi (Synchrotron)

    Mitsubishi (Synchrotron)

    Sumitomo (Cyclotron)

    ProTom (Compact Synchrotron)

    Mevion (Superconducting Synchrocyclotron)

  • Machine: Cyclotron

    IUCO cyclotron

    Excel, Varian

    IBA

  • Synchrotron: Ion beam (H+, He2+, C6+, O8+) Heidelberg, Germany (120 m)

  • Beam Line Components (IUHPTC)

    Ramping & support integrity

  • IUCF/IUH Proton Therapy System

  • Double Scattering in Fixed Beam Line (TR1); Under Upgrade

    Rudimentary, needs periodic

    QA of every component

  • Types of Beams

    Passive scattering

    Single

    Double

    Uniform scanning

    Compact magnet: 2 plane sweeping (IUCO)

    2 plane magnet: single plane sweeping (IBA)

    Pencil beam Scanning

    Spot scanning

  • IUH PTC Beam Line

    208 MeV

    ES

    KM KM KM

    KM= Kicker Magnet

    ES=Energy Selection

    TR= Treatment Room

    ES ESCyclotron

    TR1

    Scattered Beam

    Fixed Beam

    TR2

    Scanned Beam

    Gantry room

    TR3

    Scanned Beam

    Gantry room

    Useful Range= 26 cm Useful Range= 27 cm Useful Range= 27 cm

  • SOBP Redistribution

    Depth (cm)

    Dose (%)

  • 5 10 15 20 25 300

    Depth (cm)

    0.5

    1.0

    1.5

    2.0

    2.5

    3.0

    0.0

    Relative Dose

    Spread-out Bragg Peak (SOBP)

    Bragg Peak

  • Samples of Propeller Wheel Modulator

    SOBP wheel range from 2.3-16 cmQA issues with wheel

  • Kostjuchenko, Nichiporov, Luckjashin; Med Phy, 28, 1427, 2001

    Grating Ridge Filter Propeller wheel modulator

    Ridge Filter

    Spiral Ridge filter

    Ridge Filters for SOBP

  • IU Health Proton Therapy Center, Proton Gantry

    1 RPM

    Braking system within 1 deg

  • Nozzle with a Scanning Magnet at IUHPTC

    Scanning

    magnet

    ICBM

    Range

    modulator PDM Aperture

    X-ray

    Snout

  • Uniform Scanning (IUHPTC)

    Nozzle with a Scanning Magnet

    One Layer

  • Scan Parameters

    SAD 250 cm both x & y directions

    Spot size (FWHM) 12-15 mm circular

    diameter

    Frequency 5-16 Hz (horizontal), 144

    Hz (vertical) and ratio changes 5-15

    Over scan is 3 cm for optimum

    uniformity

  • Uniform Scanning and Energy Stacking Method

    Target

    Proton Pencil Beam

    Farr et al, Med Phys, 35, 4945, 2008

  • Binary Range Modulator

    6 Plates

    2 Lucite plates

    4 Graphite Plates

    Water equivalence

    3, 6, 12, 24, 48 and 96 mm

    Total range shift 18.6 cm

  • SOBP Creation Using Range Modulator

    SOBP files = Propellers

    Library 1 4-12 cm range in water

    Library 2 12-20 cm range in water

    Library 3 20-27 cm range in water

    Each library contains SOBP files

  • 0

    5

    10

    15

    20

    25

    30

    35

    40

    45

    50

    Illeg

    al b

    eam

    Flat

    ness

    MU

    1 -2

    disag

    reem

    ent

    Low

    dos

    e ra

    teFl

    oor p

    anel

    Hom

    e ga

    ntry

    Ran

    ge m

    odul

    ator

    mot

    ion

    Bea

    m sp

    ot sm

    all

    L-R in

    bala

    nce

    DM

    C

    Ben

    ding

    mag

    net

    Bea

    m li

    ne p

    anel

    Ener

    gy sp

    read

    Hall p

    robe

    Lim

    its fa

    ult

    Star

    t kic

    ker

    Star

    t tim

    e ou

    t

    Gan

    try B

    rake

    failu

    res

    PPI f

    roze

    nFi

    eld

    size

    DIP

    S cr

    ashe

    dFrequency

    May

    June

    July

    August

    September

    Treatment Room 2

    Frequency distribution of monthly faults at IUHPTC, 2009

  • 0

    5

    10

    15

    20

    25

    30

    35

    40

    45

    50

    Illeg

    al b

    eam

    MU

    1 -2

    disag

    reem

    ent

    Floo

    r pan

    el

    Ran

    ge m

    odul

    ator

    mot

    ion

    L-R in

    bala

    nce

    Ben

    ding

    mag

    net

    Ener

    gy spr

    ead

    Lim

    its fa

    ult

    Star

    t tim

    e ou

    tPP

    I fro

    zen

    DIP

    S cr

    ashe

    dFrequency

    May

    June

    July

    August

    September

    Treatment Room 3

    Frequency distribution of monthly faults at IUHPTC, 2009

  • Typical Errors

    0

    5

    10

    15

    20

    25

    30

    35Flatness

    Beam Delivery

    System (BDS)

    Ion Chmber

    Beam M

    onitor

    (ICBM)

    Range

    Modulator

    Dose D

    elivery

    System (DDS)

    PDM

    Tim

    e

    Partial

    delivery

    Frequency (%)

  • Machine Specific QA (No guidelines) Daily

    Beam line

    Flatness and Symmetry (Matrixx)

    Absolute dose

    Radiation Safety

    Monthly Beam line

    Flatness and Symmetry in 10, 20, 30 cm diameter snout

    Absolute dose (water)

    Range (Low, Medium and High) using MLIC

    Quarterly (optional of site dependent) Mechanical

    Selected QA, gantry and imaging system

    Radiation Safety

    Annual Comprehensive

    Mechanical, Nozzle, DIPS

    Dosimetry

    Gantry angle dependence

    Needs guidelines sim

    ilar to TG-142

  • 0 deg90 deg

    180 deg CCW270 deg

    Mechanical Isocenter Check

  • Diam. 1.02 mm

    Isocentricity by Film

  • Linearity vs PDM Gain (Volt)

    TR3 CVOLT Linearity Vs. Markus Ion Chamber Charge

    y = 0.1383x + 0.3469

    R2 = 0.9834

    y = 0.1437x + 0.354

    R2 = 0.9847

    0.6400

    0.6450

    0.6500

    0.6550

    0.6600

    0.6650

    0.6700

    0.6750

    0.6800

    2.000 2.100 2.200 2.300 2.400

    CVOLTS (V)

    CVOLT DMC1

    CVOLT DMC2

    Linear (CVOLT DMC2)

    Linear (CVOLT DMC1)

    TR3 CVOLT Linearity Vs. Markus Ion Chamber Charge

    y = 0.1383x + 0.3469

    R2 = 0.9834

    y = 0.1437x + 0.354

    R2 = 0.9847

    0.6400

    0.6450

    0.6500

    0.6550

    0.6600

    0.6650

    0.6700

    0.6750

    0.6800

    2.000 2.100 2.200 2.300 2.400

    CVOLTS (V)

    CVOLT DMC1

    CVOLT DMC2

    Linear (CVOLT DMC2)

    Linear (CVOLT DMC1)

    0.6400

    0.6450

    0.6500

    0.6550

    0.6600

    0.6650

    0.6700

    0.6750

    0.6800

    Collected Charge (nC)

    0.6400

    0.6450

    0.6500

    0.6550

    0.6600

    0.6650

    0.6700

    0.6750

    0.6800

    Collected Charge (nC)

  • Dose Monitor Linearity

    TR3 Ion Chamber Charge vs. DDS Requested MU

    (Constant Dose Rate)

    y = 0.0067x - 0.0401

    R2 = 0.9992

    y = 0.0193x + 0.001

    R2 = 1

    0 100 200 300 400 500 600 700

    Markus

    A12/10

    Linear (Markus)

    Linear (A12/10)

    DDS requested MU

    0.0000

    1.0000

    2.0000

    3.0000

    4.0000

    5.0000

    6.0000

    7.0000

    8.0000

    9.0000

    10.0000

    11.0000

    12.0000

    Electrometer Charge (nC)

  • TR2 Hall Probe Curves, 2009-2012

    1000

    1100

    1200

    1300

    1400

    1500

    1600

    1700

    1800

    0 2 4 6 8 10 12 14 16 18 20 22 24 26 28

    BDS Requested Range (cm)

    TRCS Hall Probe Reading (DAC Units)

    Feb. 2009

    Jan. 2010

    Jan. 2011

    Jan. 2012

    TR2 Hall Probe Curves, 2009-2012

    1000

    1100

    1200

    1300

    1400

    1500

    1600

    1700

    1800

    0 2 4 6 8 10 12 14 16 18 20 22 24 26 28

    BDS Requested Range (cm)

    TRCS Hall Probe Reading (DAC Units)

    Feb. 2009

    Jan. 2010

    Jan. 2011

    Jan. 2012

    TR2 Prime Curves, 2009-2012

    0

    2

    4

    6

    8

    10

    12

    14

    16

    18

    20

    22

    24

    26

    28

    0 2 4 6 8 10 12 14 16 18 20 22 24 26 28

    BDS Requested Range (cm)

    BDS Prime Measured Range (cm)

    Feb. 2009

    Jan. 2010

    Jan. 2011

    Jan. 2012

    TR2 Prime Curves, 2009-2012

    0

    2

    4

    6

    8

    10

    12

    14

    16

    18

    20

    22

    24

    26

    28

    0 2 4 6 8 10 12 14 16 18 20 22 24 26 28

    BDS Requested Range (cm)

    BDS Prime Measured Range (cm)

    Feb. 2009

    Jan. 2010

    Jan. 2011

    Jan. 2012

    Parameter Re

Recommended

View more >