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