Determination of Internal Target Volume From a Single Positron Emission Tomography/Computed Tomography Scan in Lung Cancer

• Published in: International journal of radiation oncology, biology, physics Vol. 83; no. 1; pp. 459 - 466
• Main Authors: Chang, Guoping, Ph.D, Chang, Tingting, M.S, Pan, Tinsu, Ph.D, Clark, John W., Ph.D, Mawlawi, Osama R., Ph.D
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.05.2012; Elsevier
• Subjects: Biological and medical sciences; CAT SCANNING; Female; Four-Dimensional Computed Tomography - adverse effects; Hematology, Oncology and Palliative Medicine; Humans; Lung Neoplasms - diagnostic imaging; Lung Neoplasms - pathology; Lung Neoplasms - radiotherapy; LUNGS; Male; Medical sciences; Middle Aged; Movement; Multimodal Imaging - methods; NEOPLASMS; Partial volume; PATIENTS; PET/CT; PHANTOMS; Phantoms, Imaging; PLANNING; Pneumology; POSITRON COMPUTED TOMOGRAPHY; Positron-Emission Tomography; RADIATION DOSES; Radiology; RADIOLOGY AND NUCLEAR MEDICINE; Radiotherapy Planning, Computer-Assisted - methods; Respiration; Respiratory motion; Target volume; Tomography, X-Ray Computed; Treatment planning; Tumor Burden; Tumors of the respiratory system and mediastinum; Respiratory motion; Target volume; Treatment planning; Partial volume; PET/CT; Radionuclide study; Lung disease; Radiodiagnosis; Respiratory disease; Lung cancer; Respiratory movement; Malignant tumor; Cancerology; Partial; Medical imagery; Bronchus disease; Computerized axial tomography; Positron emission tomography; Cancer; Emission tomography
• ISSN: 0360-3016; 1879-355X
• DOI: 10.1016/j.ijrobp.2011.06.2002

Purpose The use of four-dimensional computed tomography (4D-CT) to determine the tumor internal target volume (ITV) is usually characterized by high patient radiation exposure. The objective of this study was to propose and evaluate an approach that relies on a single static positron emission tomography (PET)/CT scan to determine the ITV, thereby eliminating the need for 4D-CT and thus reduce patient radiation dose. Methods and Materials The proposed approach is based on the concept that the observed PET image is the result of a joint convolution of an ideal PET image (free from motion and partial volume effect) with a motion-blurring kernel (MBK) and partial volume effect. In this regard, the MBK and tumor ITV are then estimated from the deconvolution of this joint model. To test this technique, phantom and patient studies were performed using different sphere/tumor sizes and motion trajectories. In all studies, a 4D-CT and a PET/CT image of the sphere/tumor were acquired. The ITV from the proposed technique was then compared to the maximum intensity projection (MIP) volume of the 4D-CT images. A Dice coefficient of the two volumes was calculated to represent the similarity between the two ITVs. Results The average ITVs of the proposed technique were 97.2% ± 0.3% and 81.0% ± 16.7% similar to the MIP volume in the phantom and patient studies, respectively. The average dice coefficients were 0.87 ± 0.05 and 0.73 ± 0.16, respectively, for the two studies. Conclusion Using the proposed approach, a single static PET/CT scan has the potential to replace a 4D-CT to determine the tumor ITV. This approach has the added advantage of reducing patient radiation exposure and determining the tumor MBK compared to 4D-CT/MIP-CT.