Consequences of additional use of PET information for target volume delineation and radiotherapy dose distribution for esophageal cancer
Received 13 May 2009; received in revised form 11 August 2009; accepted 14 August 2009. published online 18 September 2009.
Abstract
Background and purpose
To determine the consequences of target volume (TV) modifications, based on the additional use of PET information, on radiation planning, assuming PET/CT-imaging represents the true extent of the tumour.
Materials and methods
For 21 patients with esophageal cancer, two separate TV’s were retrospectively defined based on CT (CT-TV) and co-registered PET/CT images (PET/CT-TV). Two 3D-CRT plans (prescribed dose 50.4Gy) were constructed to cover the corresponding TV’s. Subsequently, these plans were compared for target coverage, normal tissue dose–volume histograms and the corresponding normal tissue complication probability (NTCP) values.
Results
The addition of PET led to the modification of CT-TV with at least 10% in 12 of 21 patients (57%) (reduction in 9, enlargement in 3). PET/CT-TV was inadequately covered by the CT-based treatment plan in 8 patients (36%). Treatment plan modifications resulted in significant changes (p<0.05) in dose distributions to heart and lungs. Corresponding changes in NTCP values ranged from −3% to +2% for radiation pneumonitis and from −0.2% to +1.2% for cardiac mortality.
Conclusions
This study demonstrated that TV’s based on CT might exclude PET-avid disease. Consequences are under dosing and thereby possibly ineffective treatment. Moreover, the addition of PET in radiation planning might result in clinical important changes in NTCP.
aDepartment of Radiation Oncology, University Medical Centre Groningen/University of Groningen, The Netherlands
bDepartment of Surgical Oncology, University Medical Centre Groningen/University of Groningen, The Netherlands
cDepartment of Nuclear Medicine and Molecular Imaging, University Medical Centre Groningen/University of Groningen, The Netherlands
dDepartment of Radiology, University Medical Centre Groningen/University of Groningen, The Netherlands
Corresponding author. Address: Department of Radiation Oncology, University Medical Centre Groningen, PO Box 30.001, 9700 RB Groningen, The Netherlands.
ABSTRACT