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Iort

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  • New
  • Added longer of life of 5 years
  • New
  • Said that ITV is not necessary
  • Added a zoom in
  • Added sponsors
  • Covered up the patient’s name
  • Covered up the patient’s name
  • New
  • New
  • Added definition to DSC
  • Compared it to the old ICRU and changed slightly the Low gradient case definition
  • Added sponsors
  • New
  • Transcript

    • 1. Precision in Radiation Oncology: what are the standards and how could it apply to IORT Vincent GREGOIRE, MD, PhD, hon. FRCP Radiation Oncology Dept., & Center for Molecular Imaging and Experimental Radiotherapy, Université Catholique de Louvain, St-Luc University Hospital, Brussels, Belgium
    • 2. Bataini et al, 1982 , 4 5 5 5 6 5 7 5 8 5 9 5 T o t a l d o s e ( G y ) 0 2 0 4 0 6 0 8 0 1 0 0 1 2 0 Tumor control (%) Dose-response curve for neck nodes ≤ 3 cm Tumor Control Probability (TCP)
    • 3.  Human  Monkey Baumann et al., Strahlenther Onkol 170: 131-139, 1994 Normal Tissue Control Probability (NTCP)
    • 4. Target J. John, 1974
    • 5. ICRU report 62, 1999
      • Gross Tumor Volume: GTV
      • Clinical Target Volume: CTV
      • Internal Target Volume: ITV
      • Planning Target Volume: PTV
      • Organ at Risk: OAR
      • Planning Organ at Risk Volume: PRV
      Target volumes in Radiation Oncology: ICRU 50 and 62:
    • 6. Target volumes in EBRT Before Rx-CH 46 Gy (Rx-CH) Right piriform sinus (ICDO-10: C12.9) SCC grade 2 TNM 6 th ed: T4N0M0 Fiberoptic examination CT MRI T2 FS FDG-PET
    • 7.
      • The Clinical Target Volume (CTV) is a volume of tissue that contains a demonstrable GTV and/or subclinical malignant disease at a certain probability considered relevant for therapy…,
      • The CTV is thus an anatomical-clinical concept.
      Clinical Target Volume (CTV) ICRU IMRT report Target volumes in EBRT
    • 8. Clinical Target Volume (CTV) Target volumes in EBRT
    • 9. Mesorectal subsite Lymph node regions Posterior PS Selection and delineation of Target Volume Haustermans et al., 2005
    • 10. The Planning Target Volume is a geometrical concept, introduced for treatment planning and evaluation. It is the recommended tool to shape dose distributions that ensure with a clinically acceptable probability that an adequate dose will actually be delivered to all parts of the CTV… Planning Target Volume (PTV) ICRU IMRT report Target volumes in EBRT
    • 11. CTV 2 = GTV 2 ICRU IMRT report Target volumes in EBRT PTV 1 : dose 1 CTV 1 GTV 1 (pre-RxTh CT+ iv contrast) PTV 2 : dose 2 GTV 2 (FDG-PET @ 46 Gy)
    • 12. Target volumes in IORT + EBRT CTV 1 = “tumor bed” PTV 1 = PTV 1 : dose 1 IORT PTV 2 : dose 2 CTV 2 (clinical knowledge) EBRT
    • 13. Normal tissues in EBRT
      • Distinction between “serial-like” (e.g. spinal cord) and “parallel-like organs” (e.g. parotid gland),
      • For “tubed” organs (e.g. rectum) wall delineation,
      • Remaining Volume at Risk (RVR): optimization and late effects (e.g. carcinogenesis).
      Organ At Risk (OAR) and Remaining Volume at Risk (RVR) ICRU IMRT report
    • 14.
      • PRV is a geometrical concept (tool) introduced to ensure that adequate sparing of OAR will actually be achieved with a reasonable probability ,
      • A positive OAR to PRV margin for serial organ.
      • Dose-volume constraints on OAR are with respect to the PRV,
      • Priority rules when overlapping PTVs or PTV-PRV(OAR),
      • Dose is reported to the PRV.
      Planning Organ at Risk Volume (PRV) ICRU IMRT report Normal tissues in EBRT
    • 15. IORT and Target Volumes
      • GTV is typically absent
      • Clinical definition of the CTV: “the operative bed”…
      • PTV = CTV
      • OAR = PRV are less clearly individualized
      ICRU report 71, 2004
    • 16. The Human Condition. R. Magritte, 1935
    • 17. Absorbed dose in EBRT
      • Planning aims:
        • PTV 1 : dose x , D-V constraints, …,
        • Spinal cord: D max = x Gy, …,
      • Prescription:
        • Physician’s responsibility,
        • Acceptance of doses, fraction #, OTT, D-V constraints, beam number, beam orientation, …
      • Treatment delivery:
        • Instruction file sent to the linac and/or RVS.
      Dose prescription in 3D-CRT and IMRT ICRU IMRT report
    • 18.
      • Level 1: not adequate for 3D-CRT – IMRT,
      • Level 2: standard level for dose reporting,
      • Level 3: homogeneity, conformity and biological metrics (TCP, NTCP, EUD, …) and confidence intervals.
      Dose recording in 3D-CRT and IMRT Level of reporting Absorbed dose in EBRT ICRU IMRT report
    • 19. ICRU Reference Point Not A “Typical Point” for IMRT Segments 4-7, 9-13 13 segment IM Field From Jatinder Palta, University of Florida Absorbed dose in EBRT Segment 1 Segment 2 Segment 3 Segment 8
    • 20.
      • Dose-volume reporting:
        • D v : i.e. D 50 (D median ), D 95
        • D mean
        • Near minimum dose: D 98
        • Near maximum dose: D 2
      • State the make, model and version number of the treatment planning and delivery software used to produce the plans and deliver the treatment.
      Metrics for level 2 reporting of PTV Absorbed dose in EBRT ICRU IMRT report
    • 21.
      • “ Serial-like” organs:
        • D near-max (D 98 ).
      • “ Parallel-like” organs:
        • D mean (e.g. parotid) ,
        • V d where d refers to dose in Gy (e.g. V 20 for lung).
      Metrics for level 2 reporting of PRV Absorbed dose in EBRT ICRU IMRT report
    • 22. Homogeneity and Conformity Low Homogenenity – High Conformity High Homogeneity – Low Conformity Dose Dose Dose Dose Vol Vol Vol Vol Absorbed dose in EBRT ICRU IMRT report Vol Dose Vol Dose Vol Dose Vol Dose High Homogeneity – High Conformity Low Homogeneity – Low Conformity
    • 23. IORT and dose prescription, reporting and recording
      • Level 1 (2-D) dose prescription, reporting and recording…
      • Dose prescription at 90% isodose for electron beams
      • Reporting of ICRU reference point dose, and best estimate of D min and D max
      • Recording as for EBRT
      ICRU report 71, 2004
    • 24.
      • Recommendations for common understanding and proper prescription and reporting especially in combined treatment, e.g. IORT followed by EBRT
      • Less sophisticated prescription and reporting for IORT
      • Volumetric prescription and reporting…?
      Conclusions
    • 25. Conclusions
      • ICRU recommendations still needed even for 3D-CRT and IMRT to avoid unwanted treatment heterogeneity,
      • New report based on ICRU foundations, e.g. volumes,
      • Adjustments and modifications performed when necessary, e.g. dose-volume reporting,
      • Final draft ready for early 2007 / publication in early 2008
      ICRU report on 3D-CRT and IMRT
    • 26. Recording in 3D-CRT and IMRT
      • Electronic archiving for at least the life of patient or 5 years – whatever is longer,
      • Complete reconstruction of the treatment plan and delivery record,
      • For clinical trials, longer archiving if scientifically justified.
      Absorbed dose in EBRT ICRU IMRT report
    • 27.
      • Sometimes the largest component of the margin between the GTV and CTV will be the delineation error in drawing the GTV,
      • Consideration should be made for this in the clinical margin.
      Clinical Target Volume (CTV) Target volumes in Radiation Oncology
    • 28. Planning Target Volume (PTV) Target volumes in Radiation Oncology
      • Include both “internal” and “external” variations of the CTV,
      • Separate delineation of the ITV may not be necessary,
      • Expansion of the CTV using “rolling ball” algorithms,
      • CTV to PTV margin recipe based on random and systematic errors,
      • Priority rules when overlapping PTVs or PTV-PRV,
      • Dose is prescribed and reported on the PTV.
    • 29. CTV to PTV margin recipe Target volumes in Radiation Oncology Van Herk, 2003
    • 30. Effect Dose Uncomplicated tumor control: Therapeutic Ratio Unacceptable normal tissue damage Tumour control Uncomplicated tumour control
    • 31. ICRU committee on volume and dose specification for prescribing, reporting and recording special techniques in external photon beam therapy: conformal and IMRT. Vincent GREGOIRE, M.D., Ph.D. and Thomas R. MACKIE, Ph.D.* Radiation Oncology Dept., & Center for Molecular Imaging and Experimental Radiotherapy, Université Catholique de Louvain, St-Luc University Hospital, Brussels, Belgium and * Dept. of Medical Physics, University of Wisconsin, Madison, WI, USA.
    • 32. The stone of Rosette (Champolion)
    • 33. The need for an new ICRU report on 3D-CRT and IMRT
      • Biological Target Volume (BTV): C. Ling, IJROBP 2000,
      • Hypoxic TV (HTV), Proliferation TV (PTV), …: ESTRO physics meeting, 2003,
      • working PTV (wPTV): Ciernik IF, IJROBP, 2005,
      • AAPM 2005: “… with the use of IMRT, ICRU recommendations will not be needed anymore…”.
      It was published and/or mentioned …
    • 34. ICRU committee for 3D-CRT and IMRT
      • Sponsors
        • Andr é Wambersie MD, PhD, Brussels, Belgium
        • Paul DeLuca PhD, Madison, USA
        • Reinhard Gahbauer MD, Ph.D, Columbus, USA
        • Gordon Whitmore Ph.D, Toronto, Canada
      • Chairmen
        • Vincent Grégoire MD PhD, Brussels, Belgium
        • T. Rock Mackie PhD, Madison, USA
      • Members
        • Wilfried De Neve MD PhD, Gent, Belgium
        • Mary Gospodarowicz MD, Toronto, Canada
        • Andrzej Niemierko PhD, Boston, USA
        • James A. Purdy PhD, Sacramento, USA
        • Marcel van Herk PhD, Amsterdam, The Netherlands
      • Consultants
        • Anders Ahnesjö PhD, Uppsala, Sweden
        • Michael Goiten PhD, Windisch, Switzerland
        • Nilendu Gupta PhD, Colombus, USA
    • 35. ICRU report 62, 1999 Target volumes in Radiation Oncology Unresolved issues for 3D-CRT and IMRT
      • Multiple GTV, e.g. anatomic vs functional imaging; before and during treatment, …,
      • GTV to CTV margins: clinical probability,
      • CTV to PTV margins: geometric probability; overlapping volumes,
      • ITV ???
      • OAR: open vs closed volume? Remaining normal tissues?
      • PRV: serial vs parallel OAR.
    • 36. Organ At Risk (OAR) PTV Rectal wall Rectum ICRU IMRT report Normal tissues in EBRT
    • 37. Parotid sparing with IMRT ICRU IMRT report Normal tissues in EBRT Superficial lobe Superficial and deep lobe
    • 38. “ Cheating on the PTV margins”
      • The practice of shrinking the CTV to PTV margin to accommodate an OAR is discouraged as it results in a deceptively better PTV homogeneity,
      • In IMRT the trade-off can be accomplished by changing the planning aims in the optimizer,
      • In 3-D CRT, the trade-off can be accomplished with a separate target delineation used to draw the beam boundary.
      ICRU IMRT report Target volumes in EBRT
    • 39. ICRU report 62, 1999 Absorbed dose in Radiation Oncology: ICRU 50 and 62:
      • Dose prescription:
        • Responsibility of the treating physician.
      • Dose reporting:
        • ICRU reference point,
        • Three-levels of dose reporting,
        • Point-doses: D ICRU point , D min , D max , …
      • Dose recording.
    • 40. ICRU report 62, 1999 Absorbed dose in Radiation Oncology: Unresolved issues for 3D-CRT and IMRT
      • Discrepancy between dose-volume constraint prescription and dose delivery,
      • Single point dose prescription,
      • Single point dose reporting,
      • Biological metrics (e.g. EUD, TCP, NTCP, …),
      • Uncertainties in dose reporting,
      • Quality assurance.
    • 41. Dose-Volume Reporting D 95 D 2 0 10 20 30 40 50 60 70 80 90 100 50 55 60 65 70 Dose (Gy) Percent Volume D98=60Gy D50=60Gy D v with v≠50 may require a change in prescription value D 98 D 50 is close to ICRU Reference Dose at a Point Absorbed dose in EBRT
    • 42.
      • Homogeneity:
        • - Standard deviation in dose to the PTV.
      • Conformity:
        • - Conformity Index: CI = TV/PTV,
        • Dice Similarity Coefficient (DSC):
        • DSC = TV  PTV / TV  PTV 
      Examples of metrics for level 3 reporting of PTV Absorbed dose in EBRT
    • 43. QA in 3D-CRT and IMRT
      • Appropriate QA of TPS and equipments,
      • Patient QA not limited to single-point dose check,
      • Phantom QA using measured dose and not limited to a single measurement point.
      • Independent dose calculation algorithms with similar or better dose calculation accuracy.
      Absorbed dose in EBRT
    • 44. QA in 3D-CRT and IMRT
      • Previous ICRU 5% point-dose accuracy specification replaced by a volumetric dose accuracy specification.
      • Proposed new ICRU volumetric dose accuracy specification:
        • High gradient (≥ 20%/cm): 85% of points within 5mm,
        • Low gradient (< 20%/cm): 85% of points within 5% of predicted dose normalized to the prescribed dose.
      Absorbed dose in EBRT
    • 45. ICRU committee for 3D-CRT and IMRT ICRU IMRT report GTV 1 CTV 1 PTV 1 CTV 2 PTV 2 CTV 3 PTV 3 Microscopic Extension Regional Involvement
    • 46. Example 1 ICRU IMRT report Target volumes in EBRT PTV 1 : dose 1 CTV 1 PTV 2 : dose 2 GTV 1 (pre-RxTh CT+ iv contrast) CTV 2 = GTV 1
    • 47. Dose-Volume Reporting D 50 best corresponds to the level at D ICRU-point Absorbed dose in EBRT 0 10 20 30 40 50 60 70 80 90 100 0 5 10 15 20 25 30 35 40 45 50 55 60 65 Dose (Gy) Percent Volume Differential Cumulative D 95 D 98 D 50 D 2 D 50 = 60 Gy