Assistant ProfessorPhD, University of Toronto
Sunnybrook - Odette Cancer Centre
2075 Bayview Avenue, Room TG 217
Toronto, Ontario M4N 3M5
Phone: (416) 480-5736
Lab Phone: (416) 480-6100 x3394
Fax: (416) 480-6801
Email Dr. Curtis Caldwell
Definition of Radiation Therapy Targets:
Dr. Caldwell has a strong interest in applying methods of digital image analysis and artificial intelligence to clinical problems. For example, Dr. Caldwell is conducting research focused on defining the location and extent of tumours accurately and reproducibly for radiation therapy planning purposes. Currently, the tumour contours are defined manually by physician experts from computed tomographic (CT) images. While it is often possible for the physician to determine if a tumour exists in a general area, it is much more difficult for the expert to determine the boundaries of the tumour. Dr. Caldwell and colleagues have studied this problem for both lung and head and neck cancers, finding that, in many cases, there may be relatively little overlap among the tumour volumes defined by different experts. This is a crucial problem for radiation therapy planning, as the tumour target must be accurately defined for a curative radiation dose to be delivered without giving too high a radiation dose to surrounding normal tissues.
Dr. Caldwell has found that the addition of functional information from Positron Emission Tomography (PET) imaging of the distribution of radio-labeled sugar molecules can lead to improvement in tumour volume definition. In addition, recent work has pointed the way toward using texture information, extracted from both CT and PET images, to automatically define the tumour target. Some of the types of information that can be derived by processing PET/CT images are shown in the figure below.
Projects for interested students may be arranged in several areas, including (1) developing methods of combining different sources of information (i.e., anatomic images, functional images and non-imaging information such as measures of lung function) to devise radiation therapy targets, (2) developing methods of quantative assessment of tumour response to treatment from functional images and (3) investigation of the effect of imaging protocols on the quantitative nature of the information from PET images.
Feature images derived from PET/CT images of a patient with head and neck cancer. The red arrow indicates the primary tumor. The pink arrow indicates a positive node. (a.) original CT, (b) original PET, (c) CT/PET, (d) PET Coarseness, (e) PET Busyness, (f) PET Contrast, (g) PET Entropy, (h) PET Energy, (i) PET Standard Deviation (Std Dev), (j) CT Coarseness, (k) CT Busyness, (l) CT Contrast, (m) CT Entropy, (n) CT Energy and (o) CT Std Dev
List of Key Publications:Link to Pubmed Publications
Yu H, Caldwell C, Mah K, Poon I, Balogh J, MacKenzie R, Tirona R. Automated Radiation Targeting in Head and Neck Cancer Using Region-based Texture Analysis of PET and CT Images International Journal of Radiation Oncology, Biology, Physics 2009 Oct 1;75(2):618-25
Yu H, Caldwell C, Mah K and Mozeg D. Co-registered PET/CT Based 3D Textural Characterization of Head and Neck Cancer for Radiation Planning IEEE Trans Med Imaging. 2009 Mar;28(3):374-83.
Caldwell CB, Mah K, Skinner M, Danjoux CE. Can PET provide the 3D extent of tumor motion for individualized internal target volumes? A phantom study of the limitations of CT and the promise of PET. International Journal of Radiation Oncology, Biology, Physics 2003 Apr 1;55(5):1381-93
Mah K, Caldwell CB, Ung YC, Danjoux CE, Balogh JM, Ganguli SN, Ehrlich LE. “The impact of 18-FDG PET on target and critical organs in CT-based treatment planning of patients with poorly defined Non Small Cell Lung Carcinoma: A prospective study” International Journal of Radiation Oncology, Biology, Physics 2002(Feb 1); 52: 339-350.
Caldwell CB, Mah K, Ung YC, Danjoux CE, Balogh JM, Ganguli SN, Ehrlich LE “Observer variation in contouring gross tumor volume in patients with poorly defined non-small-cell lung tumors on CT: the impact of 18FDG-hybrid PET fusion” Int J Radiat Oncol Biol Phys 2001 Nov 15;51(4):923-31
- Daniel Markel
- Michael Sattarivand