PET and radiotherapy: backgrounds and
perspectives for an effective collaboration
Lung cancer
Cristina Messa
IBFM-CNR, Università Milano
Bicocca, Istituto H San Raffaele
Milano
[18F]FDG PET in Lung Cancer
ƒ Staging :
- Lymph-nodes metastases
-Distant Metastases
ƒ Monitoring therapy
-Evaluation of response
-Predicting response (Chemotherapy)
ƒ Diagnosis:
- Solitary Pulmonary Nodules
ƒ Tumor Mapping
HSR Milano
PET/TC vs CT volume definition: lung cancer
STUDIO
N. Pazienti
%Casi var
volume
%Casi
volume
% Casi
volume
Metodo integr.
img
Kiffer 1998
15
27%
27%
--
Img AP
simulatore –
PET coronale
Debois
1998
105
52%
18%
34%
Qualitativo
Munley
1999
35
34%
34%
--
Qualitativo
Nestle
1998
34
35%
--
35%
Img AP
simulatore –
PET coronale
Giraud
2001
12
41%
41%
--
Co-registration
Mah 2002
30
22%
22%
--
Co-registration
Erdi 2002
11
100%
64%
36%
Co-registration
Messa ongoing
21
81%
52%
29%
Co-registration
Impact of PET N staging on CTV definition
STUDY
N. Pazienti
%pts with Volume
changes
%pts caused by N
staging
Munley 1999
35
34%
34% all inc
Giraud 2001
12
41%
41% all inc
Mah 2002
30
22%
22% all inc
Erdi 2002
11
100%
64% all inc
Messa on-going
21
81%
24%
(4 inc, 1 dec)
CTV reduction
CT doubtful LN
PET/CT negative LN
(High NPV)
HSR Milano
CTV increase
CT: negative LN
PET/CT: positive LN
HSR Milano
Impact of PET T mapping on CTV
definition
STUDY
N. Pazienti
%pts with
Volume
changes
%pts caused by T
mapping
Erdi 2002
11
100%
36% reduction for
atelectasis areas
Messa ongoing
21
81%
19% reduction for
atelectasis areas
38% red/inc for
central lesion
CTV Reduction
CT:
Lung lesion
PET/CT: Atelectasis
HSR - Milano
CTV Reduction
CT:
Lung lesion
PET/CT:
Atelectasis + central area
HSR - Milano
CTV Reduction
CT: Lung lesion
PET/CT: Necrosis
HSR - Milano
CTV Reduction
CT:
Lung lesion
PET/CT: Smaller T
HSR - Milano
PET/CT for lung cancer PTV:
clinical impact
• PET changes PTVs shape and dimension in a
significant number of patients
• This change is strongly influenced by N staging
• By using PET/CT, PTV changes can be also strongly
influenced by metabolic tumor mapping (anatomometabolic)
• The impact of PET/CT based PTV on therapy
planning and on short or long term patients response
needs to be defined (randomisation?)
PET/TC for lung cancer PTV:
technical impact
• The method is feasible and information can be
transferred to TPS
• Hard-ware / Software Images Co-registration of
different modalities are needed
• Region drawing is improved by PET: variability
between operators in defining GTV-CTV is
significantly reduced by PET integration with CT
• Automatic PET/CT images analysis is possible
• Guidelines for a PET/CT lesion definition are
needed
Definizione contorni PET: automatica
HSR Milano
NM-RT: topics for collaborations
• Redefine criteria for target volume enlargement starting
from PET/CT GTV
– CTV (biological)
– PTV (organ motion, set-up procedures)
• Relationship between metabolic tumor mapping and
shaped treatment volume (IMRT, Stereotactic RS,
IGRT)
• Set-up protocols to evaluate PET/CT clinical impact on
patients out-come (disease local control; side effects;
survival)