Tomé Lab

From Human Oncology

Huangguoshu International Interdisciplinary Conference on Biomedical Mathematics: Promising Directions in Imaging, Therapy Planning and Inverse Problems

The conference will be during Nov. 3-9, 2008, at the convention center of The Huangguoshu National Park of China, Guizhou, China

For details please see: http://iria.pku.edu.cn/HGS08/index.htm

For further details please go to the conference website at: http://iria.pku.edu.cn/HGS08/index.htm

Or contact one of the co-chairs:

• Professor Ming Jiang (chair, Peking University), mailto:ming-jiang@pku.edu.cn
• Professor Yair Censor (co-chair, University of Haifa), mailto:yair@math.haifa.ac.il
• Professor Ge Wang (co-chair, Virginia Polytechnic Institute & State University), mailto:wangg@vt.edu

View the list of speakers: http://iria.pku.edu.cn/HGS08/invited%20speakers.htm

Current Students (in alphabetical order)

• Noah Arvidson
• Ed Bender
• Eric Ehler
• Nick Hardcastle (visting PhD student from Centre for Medical Radiaton Physics at University of Wollongong, Australia)
• Karl Rasmussen (Joint with Dr. Steven Howard)
• Dinesh Tewatia (Joint with Dr. Bhudatt Paliwal)
• Dongxu Wang (Joint with Dr. T. Rock Mackie)

Recent Graduates and Their Current Locations

• Dr. Susan Richardson, Assistant Professor, Baylor Medical College (Huston, TX), (Joint with Dr. Bhudatt Paliwal), 2003
• Dr. Alonso Gutierrez, Assistant Professor, University of Texas (San Antonio, TX), (Joint with Dr. T. Rock Mackie), 2007
• Dr. Yusung Kim, Assistant Professor, University of Iowa (Iowa City, IA), 2007. On the web at [1]

Research topics and related publications

Treatement planning for GBM using physiologic MRI data:

Our overall goal in this project is to learn how to design better radiotherapy treatement plans for patients with GBM, whose survival rate is currently less than 3% after 5 years. We are currently investigating the utility of various physiologic MRI data for use in the treatement planning process.

• Most of the patients who receive treatement for GBM experience a recurrence of the disease within 2-4 cm of the treatement margin.
• Some patients have a recurrence within the original treatement volume. Therefore, subvolume boosting may be benificial, if high risk areas can be identified
  • "Selective Boosting of Tumor Subvolumes", Wolfgang A. Tome, Jack F. Fowler, International Journal of Radiation Oncology, Biology, Physics 48 pp. 593-599 (2000) [2]
  • On the incorporation of multi-modality image registration into the radiotherapy treatment planning process." Hazim A Jaradat, Wolfgang A Tomé, Todd R McNutt, M. Elisabeth Meyerand, "Technol Cancer Res Treat." 2003 2(1):1-12. [3]
• The MRI modalities (aside from T1/T2 weighted imaging) that we will use in this study include:
  • Hypoxia mapping using blood oxygen level dependent (BOLD) MRI with carbogen breathing
    • The lack of oxygen in hypoxic cells leads to a resistance to radiation
    • The use of carbogen breathing will help in distinguishing between tumors and necrosis or dried blood
    • We will attempt to identify regions of chronic hypoxia and use this information in the treatement plans
  • Chemical shift imaging (CSI) and the choline:N-acetylaspartate index (CNI)
    • Several metabolites can be detected, including choline, creatine, N-acetylaspartate, and lactate
    • The metabolic fingerprint of tumors is different than that of normal brain tissue and this can be used in the treatement planning process
  • Contrast enhanced perfusion imaging
    • Used to measure blood flow and volume
    • Hypervascular regions show up as areas of high signal intensity
    • Cerebral blood volume can be used to identify highly proliferative tumors
  • Diffusion imaging and the apparent diffusion coefficient (ADC)
    • Regions with a low ADC indicate a high cellularity and may indicate a region of rapid tumor growth

Whole brain radiotherapy with hippocampal avoidance

• The hippocampus is a deep brain structure (actually a pair of structures, one left and one right) which contains neural stem cells. Damage to the hippocampus during radiotherapy may lead to neurocognitive impairment. It therefore may be desirable to spare a patients hippocampus during whole brain radiotherapy (a typical treatment for patients with multiple brain metastases). The difficulty in this is that it is hard to see the hippocampus on MRI images. We are in the process of developing an automatic method for generating a conformal avoidance region for a patients hippocampus. To do this, an expert outlined the hippocampi in the MRI images for 100 patients, and using deformable image registration an average hippocampus was generated in a template MRI image set. Next, this average hippocampus is deformed to a given patient and then expanded in all directions to define a conformal avoidance region. The details of this procedure were chosen such that the volume of the resulting conformal avoidance region was approximately the same as if the actual hippocampus were expanded by 5mm in all directions (5mm being the current clinical standard). The figure below shows an example of this automatically generated conformal avoidance region in green, and for comparison the manually segmented hippocampus in red. Note that the green contour was generated automatically, without using the actual hippocampus.

• publications:
  • "Distribution of Brain Metastases in Relation to the Hippocampus: Implications for Neurocognitive Functional Preservation." Ghia A, Tomé WA, Thomas S, Cannon G, Khuntia D, Kuo JS, Mehta MP. International journal of radiation oncology, biology, physics, (2007) [4]
  • "Whole Brain Radiotherapy With Hippocampal Avoidance and Simultaneously Integrated Brain Metastases Boost: A Planning Study." Alonso Gutiérrez, David Westerly, Wolfgang Tomé, Hazim Jaradat, Thomas Mackie, Søren Bentzen, Depak Khuntia, Minesh Mehta, International Journal of Radiation Oncology Biology Physics 69 pp. 589-597 (2007) [5]

Treatement planning for lung tumors using 4D-CT

• publications:
  • "On the automated definition of mobile target volumes from 4D-CT images for stereotactic body radiotherapy." Zhang T, Orton NP, Tomé WA. "Med Phys." 2005;32(11):3493-502.[6]
  • "On the Dose Delivered to a Moving Target When Employing Different IMRT Delivery Mechanisms", Ehler E, Nelms BE, and Tomé WA, Radiotherapy and Oncology 83, p. 49-56 (2007). [7]
  • "A 4D IMRT/SBRT and respiratory gating QA device for patient-specific intra-fraction motion kernels" Nelms BE, Ehler E, Bragg H, Tomé WA, Journal of Applied Clinical Medical Physics 8, pp. 152-168 (2007). [8]

Pulsed reduced dose-rate radiotherapy

Pulsed reduced dose-rate radiotherapy is a radiotherapy technique in which the dose-rate at which the treatment is delivered is substantially reduced. This is done by delivering the entire treatment dose as a series of 0.2 Gy pulses separated by 3 minute time intervals, creating an apparent dose rate of 0.0667 Gy per minute.

• publications:
  • "Pulsed reduced dose-rate radiotherapy: case report: a novel re-treatment strategy in the management of recurrent glioblastoma multiforme.", George M. Cannon, Wolfgang A. Tomé, H. Ian Robins and Steven P. Howard, Journal of Neuro-Oncology 83, 307-311 (2007) [9]
  • "On the possible increase in local tumour control probability for gliomas exhibiting low dose hyper-radiosensitivity using a pulsed schedule", W A Tomé, and S P Howard, The British Journal of Radiology 80, 32-37 (2007) [10]
  • "Pulsed reduced dose-rate radiotherapy: a novel locoregional retreatment strategy for breast cancer recurrence in the previously irradiated chest wall, axilla, or supraclavicular region.", GM Richards, WA Tomé, HI Robins, JA Stewaer, JS Welsh, PA Mahler, SP Howard, "Breast Cancer Res Treat." "2008 Apr 4. [Epub ahead of print] PMID: 18389365 [11]

Risk Adaptive Radiotherapy

Risk Adaptive Radiotherapy is a biological optimization strategy that is based on the possible risk characteristics for local recurrence in tumor sub-volumes rather than individual tumor voxels and treatment plans are optimized using biological objective functions that are region specific, rather than voxel specific.

• publications:
  • "Risk-adaptive optimization: selective boosting of high-risk tumor subvolumes" Yusung Kim and Wolfgang A Tomé, International Journal of Radiation Oncology, Biology, Physics 66, pp. 1528–1542 (2006) [12]
  • "Radiobiological and treatment planning study of a simultaneously integrated boost for canine nasal tumors using helical tomotherapy." Gutíerrez AN, Deveau M, Forrest LJ, Tomé WA, Mackie TR. "Vet Radiol Ultrasound." 2007;48(6):594-602.[13]
  • "Optimization of radiotherapy using biological parameters." Kim Y. and Tomé WA, "Cancer Treat Res." 2008;139:257-78. Review [14]
  • "On the impact of functional imaging accuracy on selective boosting IMRT." Yusung Kim and Wolfgang A Tomé, "Phys Med." 2008 Jan 16. [Epub ahead of print] PMID: 18206411 [15]

Useful Links

• The American Association of Physicists in Medicine [16]

• The American Board of Radiology - Radiologic Physicists [17]