Compared it to the old ICRU and changed slightly the Low gradient case definition
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
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)
Human Monkey Baumann et al., Strahlenther Onkol 170: 131-139, 1994 Normal Tissue Control Probability (NTCP)
Clinical Target Volume (CTV) Target volumes in EBRT
Mesorectal subsite Lymph node regions Posterior PS Selection and delineation of Target Volume Haustermans et al., 2005
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
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
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.
CTV to PTV margin recipe Target volumes in Radiation Oncology Van Herk, 2003
Effect Dose Uncomplicated tumor control: Therapeutic Ratio Unacceptable normal tissue damage Tumour control Uncomplicated tumour control
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.
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
ICRU report 62, 1999 Absorbed dose in Radiation Oncology: ICRU 50 and 62:
Responsibility of the treating physician.
ICRU reference point,
Three-levels of dose reporting,
Point-doses: D ICRU point , D min , D max , …
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,
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