first experiences and results karen feyen az st maarten duffel belgium
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First Experiences and Results Karen Feyen AZ St-Maarten Duffel , Belgium. A Cylindrical 3D Water Scanner –. A.Z. Sint-Maarten – RT department - Linacs. SLi 18 (installed 2002), conformal treatments 6MV/15MV photons 5 electron energies MLCi with 1 cm leaves, max field size 40 cm x 40 cm

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a z sint maarten rt department linacs
A.Z. Sint-Maarten – RT department - Linacs
  • SLi 18 (installed 2002), conformal treatments
    • 6MV/15MV photons
    • 5 electron energies
    • MLCi with 1 cm leaves, max field size 40 cm x 40 cm
    • Short physics duct from control area to linac technical area : no fixed cabling
  • Synergy platform (installed 2007), IMRT
    • 6MV/15MV photons
    • Beam modulator with 4 mm leaves, max field size 21 cm x 16 cm
    • Physics duct about 25 m, fixed cabling and connectors in bunker and control area
  • EPID based IGRT on both systems
    • Iview GT
    • Vanderwilt remote table control
    • Offline/online protocols, no CBCT
  • ± 1000 new patients/year
a z sint maarten rt department
A.Z. Sint-Maarten – RT department
  • CT simulation
    • Siemens Definition CT (medical imaging department)
    • A2J CT-Sim lasers
    • Medio 50 CP simulator used for some palliative
    • Medio 50 CP simulator
    • Some palliative treatments
  • Main TPS = Pinnacle
  • Brachy:
    • Nucletron HDR / Oncentra Masterplan
    • PBT inhouse/other centers : Bard / Variseed
  • Other equipment
    • More than 40 PC’s and workstations for about 20 people
    • A lot of cables and a lot of heat
dosimetry material
Dosimetry material
  • Abolute Dosimetry
    • FC-65-G cylindrical reference chamber
    • PPC-40 parallel plate chamber
    • Dose-1 electrometer
    • WP1D motorised waterphantom
  • Machine QA - SNC
    • Switching to IC-profiler or Profiler 2 (still to be decided)
    • Daily QA3 (wireless)
  • Patient QA
    • Matrixx
    • Invidos
  • Brachy QA
    • Unidos E and Sourcecheck (PBT)
    • Nucletron/Standard Imaging and PTW well chamber (HDR)
3ds how did we decide
3DS – How did we decide ?
  • Motivation :
    • WP700 system dates from 1989 and was in need for replacement
    • “New” project : commission Sli 18 for IMRT, we wanted this done without doubts about the measurement data quality
    • Increase time efficiency of water tank measurements
    • Reduce threshold to use of water tank
  • Obtained budget approval 04/2010
3ds how did we decide1
3DS – How did we decide ?
  • Requirements specifications (highlights):
    • Must
      • qualitatively perform as well or better than the old system (of course)
      • work with current detectors
      • handle current data
      • export to Pinnacle
      • TMR/TPR capable
      • Before purchase, we must work with the system to get the look and feel
    • Should
      • more user friendly
      • easier/faster to setup
3ds how did we decide2
3DS – How did we decide ?
  • On site visits at nearby centers May-June 2010
    • PTW MP3-M / Mephysto MC2
    • IBA Blue Phantom / OmniPro Accept v7

 both very qualitative and well established systems

      • IBA blue phantom and OmniPro Accept v7 seemed logical successor to our current system
  • No clinical 3DS system available in Europe at that time
  • => Visit to SNC factory
3ds how did we decide3
3DS – How did we decide ?
  • Visit SNC factory
    • First view on a functional prototype
    • Opportunity to talk to several people involved in the development of hardware and software
  • Enthousiastic team determined to deliver a innovative and qualitative product, eager to take input from (potential) users
  • Good overview of hardware, software
  • But system released early 2011, which was later than we hoped for
3ds how did we decide4
3DS – How did we decide ?
  • Competitive offers from all parties
  • Open communication with all distributors
  • Detailed comparison of all specs
  • Choice between solid well established system and young innovative system
  • Very much attracted by the novelties of the 3DS system
    • Auto setup : objective, time saving (?),
    • One-cable connection : fast, less fragile
    • Measurement database instead of files
    • Layered processing with rollback options
    • Consistent detector orientation (certainly has a positive effect but not thoroughly evaluated at that time)
3ds how did we decide5
3DS – How did we decide ?
  • But no reference and no opportunity to test at that time

=> Test site agreement

    • Gain experience with new system before it is released
    • Opportunity to provide input for new features (wish list !)
    • Possibly start measurements with test system if all works earlier than planned (optimism is good)
3ds the system1
3DS – the system
  • Main hardware differences :
    • Cylindrical geometry
      • movement in (r, theta, z) instead of (x, y, z)
      • Look less bulky
      • less water needed, less weight
      • scan range is the same for all scans ( i.e. not larger for diagonals) but is large (standard 50 cm)
      • larger scan range possible with special detector holder
mechanical testing
Mechanical Testing
  • Relative positioning accuracy using laser pointer and chart paper
    • Ring drive
    • Vertical drive
    • Diameter drive
  • Done using controls box – without auto setup measurements (dry tank)
  • Leveling accuracy : ≤ 0.1° (accuracy of our digital level)
  • Plumb line of vertical drive using laser level (construction)
3ds s etup
3DS – Setup
  • Platform setup procedure:
    • Connect power and PDI
    • Calibrate motors platform and tank
    • Put tank approximately right
    • Fill tank and adjust height to correct SSD
    • Leave bunker and run auto setup procedure
      • Tank Leveling
      • Ring center determination
      • Tank center determination and tank adjustment
      • Ring angle offset determination
      • Hysteresis measurement
3ds auto setup calibrate platform
3DS – Auto setup – calibrate platform
  • Platform leveling and x- y- motors need to be calibrated before they can be used
  • Best done before aligning the system with the crosswire
3ds auto setup calibrate platform1
3DS – Auto setup – calibrate platform
  • Tank ring drive, diameter drive and vertical drive home positions are determined
3ds auto setup ring center
3DS – Auto setup – ring center
  • Diameter drive is mounted eccentrically to allow for the detector to be in the center
3ds auto setup ring center1
3DS – Auto setup – Ring center
  • To keep the detector in the mechanical center of the tank, it must be positioned correctly
  • In the direction orthogonal to the diameter drive -> specific distance when mounting the detector
  • In the direction along the diameter drive -> done by the system
3ds auto setup ring center2
3DS – Auto setup – Ring center
  • If the ring center would not be determined correctly, the detector would rotate on a circle around the mechanical center
3ds auto setup2
3DS – Auto setup
  • Tank adjust
    • The isocenter/beam center is determined from
      • Inline and crossline scan at collimator 0°
      • Inline and crossline scan at collimator 180°
    • The tank position is shifted to match the beam center
  • Angle offset
    • The angle of the tank is aligned with the collimator
3ds auto setup checks
3DS – Auto setup Checks
  • Check after auto setup during test period:
    • Visually check position of detector vs crosswire
    • Take scans at cardinal angles
    • Check correct position of beam edges
  • => Part of factory testing
3ds scan database
3DS – Scan database
  • Scans are grouped in projects – can be added to multiple projects
  • DB can be searched by building logical expressions of various scan parameters
  • Scan lists can filtered
  • Scans lists can be grouped
results large scan range
Results – Large scan range
  • The standard scan range of 50 cm can be extended using the radial offset detector holder
  • 40 cm x 40 cm, d=30cm, 5 cm extra => 62cm scan
results large scan range1
Results – Large scan range
  • Radial offset detector offsets the detector from the center of the carriage, brings it closer to the tank wall
  • Diameters driver rotates by 180° when detector is in the center
results consistent detector orientation
Results – Consistent detector orientation
  • The cylindrical design ensures a consistent orientation of the detector : the motion always occurs transverse to the axis of the detector
results consistent detector orientation1
Results – Consistent detector orientation
  • Intuitively important for
    • extended detectors
    • detectors with different dimensions along their respective axis
  • Tested with 3 types of detectors
    • elongated IC
    • “spherical” IC (CC13)
    • diode
  • Compared scans with axis
    • transverse to motion
    • along the direction
results evaluation of scan parameters
Results – Evaluation of scan parameters
  • Set of scans for various field sizes and various scan settings – CC13
results evaluation of scan parameters1
Results – Evaluation of scan parameters
  • Set of scans for various field sizes and various scan settings – Edge (diode)
results detector choice small fields
Results – Detector choice – small fields
  • Set of scans for various detectors and optimal scan settings
  • “Sharp” vs noisy
results detector choice large fields
Results – Detector choice – large fields
  • Set of scans for various detectors and optimal scan settings
  • “Sharp” vs noisy
results scans with offset
Results – Scans with offset
  • Achieved by either
    • Software controlled shift of platform (offsets ~ 1cm)
    • By combination of radial and angular movement (larger offsets)
results scans with offset1
Results – Scans with offset
  • Check off-axis shift
  • Collimator 45°
  • Scan with no offset /
  • Scan with 1 cm offset
results scans with offset2
Results – Scans with offset
  • Check detector position ?
summary of my findings
Summary of my findings
  • 3DS is a nice innovative system to work with : no more dreading to use it
    • Less bulky, less heavy, practical design
    • Auto setup : objective, fast(er)
    • One-cable connect
    • Database of measurement : very helpful during comissioning
    • Layered processing

=> Faster, more frequent use

  • Still being optimised and developped further based on user feedback => real strength of SNC
acknowledgements
Acknowledgements
  • My colleague physicists, for all extra work during evenings and weekends:
    • Natalie Bal
    • Charlotte Bauwens
  • Our department head dr. Ph. Spaas

Thank you !

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