Integrating Technology for Radiotherapy in Prostate Cancer Peter - - PowerPoint PPT Presentation

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Integrating Technology for Radiotherapy in Prostate Cancer Peter - - PowerPoint PPT Presentation

Oct 08, 2022 145 likes •613 views

Integrating Technology for Radiotherapy in Prostate Cancer Peter Chung Department of Radiation Oncology Radiation Medicine Program Princess Margaret Hospital High risk Prostate Cancer - Canadian Consensus Intermediate risk Gleason score

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Integrating Technology for Radiotherapy in Prostate Cancer

Peter Chung

Department of Radiation Oncology Radiation Medicine Program Princess Margaret Hospital

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Prostate Cancer - Canadian Consensus

Gleason score PSA T-stage High risk Intermediate risk Low risk

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Radiotherapy Treatment Indications

  • Brachytherapy
  • External beam RT
  • Combined B/EBRT

Low risk Intermediate risk High risk Postoperative

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Results - Low risk

Zelefsky et al, 2007

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Results - Intermediate risk

Kuban et al, 2008

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Results - High risk

Bolla et al, 2002

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Dose

  • Large trials confirm that higher dose improve

cancer control – become standard of care

– Independent of type of radiation used

  • Now - limit collateral injury to rectum,

bladder, erectile structures

– Reduce the volume of normal tissue exposed to high-dose

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Approach

  • Improve precision and accuracy

– IMRT (Intensity Modulated Radiotherapy) – IGRT (Image-Guided Radiotherapy)

  • Target cancer instead of organs

– Imaging

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EBRT – Past

Cobalt ‘bomb’ – Johns et al

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EBRT – Past

24Gy

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Linear Accelerator

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EBRT – Linear Accelerator

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Dose Distribution

7700 7400 7030 4370 3700

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Dose Distribution

7700 7400 7030 4370 3700

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Toxicity

3d conformal

Zelefsky et al

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Step-by-step process - Planning

  • Patient education + Prep instructions
  • Immobilisation - VacLok
  • CTSim - 2mm slices for DRR generation
  • Contouring
  • PTV margin generation – 10mm (7mm post)
  • IMRT planning
  • Physics QA
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New technologies

  • Planning RT

– VMAT

  • Tracking the prostate

– GPS, soft tissue, US

  • Improved imaging

– MRI

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High Precision Radiotherapy

  • Identifying the tumour
  • Knowing where the tumour is during

treatment

  • Accurate targeting of the tumour
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MRI

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Extracapsular Extension

  • Rectoprostatic angle

Choyke et al.

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MRI Disease

  • Low T2
  • Fast T1 contrast

enhancement & washout

  • Low diffusivity
  • High Choline / Citrate

Haider et al.

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MRI Disease

  • Low T2
  • Fast T1 contrast

enhancement & washout

  • Low diffusivity
  • High Choline /

Citrate

Choyke et al.

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Disease

  • Low T2
  • Fast T1 contrast

enhancement & washout

  • Low diffusivity
  • High Choline /

Citrate

Haider et al.

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Anatomic Resolution

Rosewall et al.

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Post-Prostatectomy

Ménard et al.

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Missing the Target

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Image Guidance

  • Accurately directing

radiation to the target

  • Improves precision
  • Reduces normal tissue in

the treatment volume

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IMRT Prep

  • Fiducial markers
  • CT/MR simulation
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8.7 min (sd 2.3) Adjusted 6.1 min (sd 1.3) Unadjusted Mean time 1st image to last beam

11% 5mm 19% 3mm 38% 1mm 28% 2mm

Frequency Action Level

Chung et al

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Cone beam CT

MV Markers: Template matching CBCT Markers: Auto-segmentation CBCT Soft Tissue: Reference contour

Vs Vs

Couch Shift: x,y,z

Moseley et al

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Results

2.5 ∑ + 0.7 σ

σ = 0.58, 1.29, 1.27 Σ = 0.35, 0.99, 0.98 σ = 0.89, 2.24, 2.27 Σ = 0.51, 2.22, 1.17

MV Markers CBCT Markers

van Herk’s Margin Recipe

R/L A/P S/I R/L A/P S/I

Margin 1.3 mm 3.4 3.3 Margin 1.9 mm 7.1 4.5

CBCT Soft Tissue

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Noel et al , 2009

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Volumetric Modulated Arc Therapy

(VMAT)

  • Continuous irradiation with gantry

motion;

– as in conventional arc therapy.

  • Field shape changes with rotation;

– “Arbitrary” fluence patterns at each gantry angle fall within a single arc.

Otto et al

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7 field Step-and-Shoot 5.6 minutes 362 MU 360 degree arc VMAT 1.0 minutes 421 MU 360 degree arc VMAT 4.2 minutes 442 MU

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Rectum DVH

VMAT (dashed), S&S (solid)

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Focusing on the Tumor

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Conclusions

  • Radiotherapy continues to evolve
  • Dynamic process
  • Old and new technologies continue to

advance the ‘state of the art’

  • Delivery of dose to a specified target with

sparing of normal tissue as a goal is achievable…….we are not there…….yet

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Oncology Andrew Bayley Rob Bristow Charles Catton Juanita Crook Saibish Elantholiparameswaran Mary Gospodarowicz Mike McLean Cynthia Menard Mike Milosevic Padraig Warde

Acknowledgements

Physics Hamideh Alasti Tim Craig Anna Kirilova Team 3 Physicists Trials Debbie Tsuji Bernadeth Lao Therapists Tara Rosewall Vickie Kong Jing Yan Val Kelly Tony Lam Jan Patterson Glennis Savage Lorie Divanbeigi Team 3 Planners Team 3 Therapists