4dct driving improved lung radiotherapy outcomes at ncci
TRANSCRIPT
4 Dimensional CT Driving Improved Lung Radiotherapy Outcomes at NCCI
G Livingston, L Connors, A Fonseca, V Connors, P Dwyer and A Last
North Coast Cancer Institute
• 3 Departments
• 6 Linear Accelerators
• 7 Radiation Oncologists.
• 12 Physicists
• 55ish Radiation Therapists (including specialty roles – Thoracic RT)
• ≈ 2000 Tx per annum
What’s the problem with Conventional CT?
• Tumour Distortions = poor visualisation the tumour
• Poor information regarding motion = cannot be sure where or if it moves
• Target Delineation errors = less appropriate target size
• Less accurate treatment alignment. = rely on bony surrogates.
Video of RSD phantom
4DCT solution
• Low-pitched CT scan which images each slice of the patient throughout each phase of the respiratory cycle to produce a series of respiratory phase correlated 3DCT scans.
• 4th dimension is respiratory phase.
CT Data
Amplitude 3D PTV average
4D PTV average Change (%)
Small (0-5mm) n = 12
309cc
281cc
9.1%
Medium (5-10mm) n = 7
194cc
213cc
9.8%
Large (>1cm) n = 1
167cc
238cc
42.5%
PTV Size comparison (n=20)
Improved Treatment Alignment
JAN-JAKOB SONKE, PH.D., JOOS LEBESQUE, PH.D., M.D., AND MARCEL VAN HERK, PH.D. VARIABILITY OF FOUR-DIMENSIONAL COMPUTED TOMOGRAPHYPATIENT MODELS Int. J. Radiation Oncology Biol. Phys., Vol. 70, No. 2, pp. 590–598, 2008
Improved Treatment Alignment
JAN-JAKOB SONKE, PH.D., JOOS LEBESQUE, PH.D., M.D., AND MARCEL VAN HERK, PH.D. VARIABILITY OF FOUR-DIMENSIONAL COMPUTED TOMOGRAPHYPATIENT MODELS Int. J. Radiation Oncology Biol. Phys., Vol. 70, No. 2, pp. 590–598, 2008
Bony alignment: additional 2mm margin surrounding the Target. Neilson T, Hansen V, Westberg J, Hansen O, Brink C. A DUAL CENTRE STUDY OF SETUP ACCURACY FRO THORACIC PATIENTS BASED ON CONE-BEAM CT DATA. Radiother Oncol Vol. 102, pp. 281–286, 2012
SABR (Stereotactic Ablative Body Radiotherapy)
- very high doses (>100Gy RBE)
- very few fractions (1-5#)
- very small margins (GTV/ITV + 5mm)
- high precision (Planning and Treatment)
- highly dependent on 4D imaging
Locally Advanced NSCLC
Grade 2+ Radiation Pneumonitis ~
30% (including 1-2% fatal). Palma et al 2013
(2012) NCCI implemented 4DCT +
IMRT + Daily CBCT as the standard.
- Maximising accuracy of RT
- Minimising dose to healthy
lung, oesophagus and heart
Thank Youthank you to Andrew Last, Pat Dwyer, Lisa Connors, Amara Fonseca, Vanessa
Connors and the NCCI Team