Search

Your search keyword '"Ibbott, Geoffrey S."' showing total 946 results
Start Over Author "Ibbott, Geoffrey S."
946 results on '"Ibbott, Geoffrey S."'

2. Simultaneous Motion Monitoring and Truth-In-Delivery Analysis Imaging Framework for MR-guided Radiotherapy

Author

Mickevicius, Nikolai J., Chen, Xinfeng, Boyd, Zachary, Lee, Hannah J., Ibbott, Geoffrey S., and Paulson, Eric S.

Subjects
Physics - Medical Physics
Abstract

Intrafraction motion can play a pivotal role in the success of abdominal and thoracic radiation therapy. Hybrid magnetic resonance-guided radiotherapy systems have the potential to control for intrafraction motion. Recently, we introduced an MRI sequence capable of acquiring real-time cine imaging in two orthogonal planes (SOPI). We extend SOPI here to permit dynamic updating of slice positions in one plane while keeping the other plane position fixed. In this implementation, cine images from the static plane are used for motion monitoring and as image navigators to sort stepped images in the other plane, producing dynamic 4D image volumes for use in dose reconstruction. A custom 3D-printed target filled with radiochromic FXG gel was interfaced to a dynamic motion phantom. 4D-SOPI was acquired in a dynamic motion phantom driven by an actual patient respiratory waveform displaying amplitude/frequency variations and drifting and in a healthy volunteer. Unique 4D-MRI epochs were reconstructed from a time series of phantom motion. Dose from a static 4cmx15cm field was calculated on each 4D respiratory phase bin and epoch image, scaled by the time spent in each bin, and then rigidly accumulated. The phantom was then positioned on an Elekta MR Linac and irradiated while moving. Following irradiation, actual dose deposited to the FXG gel was determined by applying a R1 versus dose calibration curve to R1 maps of the phantom. The 4D-SOPI cine images produced a respiratory motion navigator that was highly correlated with the actual phantom motion (CC=0.9981). The mean difference between the accumulated and measured dose inside the target was 4.4% of the maximum prescribed dose. These results provide early validation that 4D-SOPI simultaneously enables real-time motion monitoring and truth-in-delivery analysis for integrated MR-guided radiation therapy (MR-gRT) systems., Comment: 26 pages, 12 figures, submitted to Physics in Medicine and Biology

Published
2018
Full Text
View/download PDF

3. Dose Verification of Volumetric Modulated Arc Therapy using One and Two Dimensional Dosimeters

Author

Rehman, Jalil ur, Zahra, Hussain, Ghulam, Ahmad, Nisar, Asghar, H M Noor ul Huda Khan, Gilani, Zaheer Abbas, Nasar, Gulfam, Akhter, Malik M, Isa, Muhammad, and Ibbott, Geoffrey S.

Subjects
Physics - Medical Physics
Abstract

Purpose: To verify dose delivery and quality assurance of volumetric modulated arc therapy (VMAT) for head and neck cancer. Method: The Imaging and Radiation Oncology Core Houston (IROC-H) head and neck phantom with thermo- luminescent dosimeters (TLDs) and films, were imaged with computed tomography scan and the reconstructed image was transferred to pinnacle treatment planning system (TPS). On TPS the planning target volume (PTV), secondary target volume (STV) and organ at risk (OAR) were delineated manually and a treatment plan was made. The dose constraints were determined for the concerned organs according to IROC-H prescription. The treatment plan was optimized using adoptive convolution algorithm to improve dose homogeneity and conformity. The dose calculation was performed using C.C Convolution algorithm and a Varian True Beam linear accelerator was used to deliver the treatment plan to the head and neck phantom. The delivered radiation dose to the phantom was measured through TLDs and GafChromic EBT2 films. The dosimetric performance of the VMAT delivery was studied by analysing percent dose difference, iso-dose line profile and gamma analysis of the TPS computed dose and linac delivered doses. Result: the percent dose difference of 3.8\% was observed between the planned and measured doses of TLDs and a 1.5mm distance to agreement (DTA) was observed by comparing iso-dose line profiles. Passed the gamma criteria of 3\%/3 mm was with good percentages. Conclusion: The dosimetric performance of VMAT delivery for a challenging head and neck radiotherapy can be verified using TLDs and films imbedded in an anthropomorphic H\&N phantom., Comment: 12 pages, 4 figures

Published
2018

4. The report of Task Group 100 of the AAPM: Application of risk analysis methods to radiation therapy quality management

Author

Huq, M Saiful, Fraass, Benedick A, Dunscombe, Peter B, Gibbons, John P, Ibbott, Geoffrey S, Mundt, Arno J, Mutic, Sasa, Palta, Jatinder R, Rath, Frank, Thomadsen, Bruce R, Williamson, Jeffrey F, and Yorke, Ellen D

Subjects
Medical and Biological Physics, Physical Sciences, Cancer, Patient Safety, Humans, Medical Errors, Neoplasms, Quality Assurance, Health Care, Radiotherapy Planning, Computer-Assisted, Radiotherapy, Intensity-Modulated, Risk Assessment, process mapping, FMEA, FTA, risk-based-QM program, Other Physical Sciences, Biomedical Engineering, Oncology and Carcinogenesis, Nuclear Medicine & Medical Imaging, Biomedical engineering, Medical and biological physics
Abstract

The increasing complexity of modern radiation therapy planning and delivery challenges traditional prescriptive quality management (QM) methods, such as many of those included in guidelines published by organizations such as the AAPM, ASTRO, ACR, ESTRO, and IAEA. These prescriptive guidelines have traditionally focused on monitoring all aspects of the functional performance of radiotherapy (RT) equipment by comparing parameters against tolerances set at strict but achievable values. Many errors that occur in radiation oncology are not due to failures in devices and software; rather they are failures in workflow and process. A systematic understanding of the likelihood and clinical impact of possible failures throughout a course of radiotherapy is needed to direct limit QM resources efficiently to produce maximum safety and quality of patient care. Task Group 100 of the AAPM has taken a broad view of these issues and has developed a framework for designing QM activities, based on estimates of the probability of identified failures and their clinical outcome through the RT planning and delivery process. The Task Group has chosen a specific radiotherapy process required for "intensity modulated radiation therapy (IMRT)" as a case study. The goal of this work is to apply modern risk-based analysis techniques to this complex RT process in order to demonstrate to the RT community that such techniques may help identify more effective and efficient ways to enhance the safety and quality of our treatment processes. The task group generated by consensus an example quality management program strategy for the IMRT process performed at the institution of one of the authors. This report describes the methodology and nomenclature developed, presents the process maps, FMEAs, fault trees, and QM programs developed, and makes suggestions on how this information could be used in the clinic. The development and implementation of risk-assessment techniques will make radiation therapy safer and more efficient.

Published
2016

6. Effect of Brachytherapy With External Beam Radiation Therapy Versus Brachytherapy Alone for Intermediate-Risk Prostate Cancer: NRG Oncology RTOG 0232 Randomized Clinical Trial

Author

Michalski, Jeff M., primary, Winter, Kathryn A., additional, Prestidge, Bradley R., additional, Sanda, Martin G., additional, Amin, Mahul, additional, Bice, William S., additional, Gay, Hiram A., additional, Ibbott, Geoffrey S., additional, Crook, Juanita M., additional, Catton, Charles N., additional, Raben, Adam, additional, Bosch, Walter, additional, Beyer, David C., additional, Frank, Steven J., additional, Papagikos, Michael A., additional, Rosenthal, Seth A., additional, Barthold, H. Joseph, additional, Roach, Mack, additional, Moughan, Jennifer, additional, and Sandler, Howard M., additional

Published
2023
Full Text
View/download PDF

12. Quality Assurance of Clinical Trials in the Management of Cancer in the Head and Neck

Author

FitzGerald, Thomas J., Bishop-Jodoin, Maryann, Urie, Marcia M., Ulin, Kenneth, Ibbott, Geoffrey S., Purdy, James A., Saltz, Joel H., Peters, Lester J., Cicchetti, M. Giulia, Schnall, Mitchell, Deasy, Joseph, Bosch, Walter R., Knopp, Michael V., Schwartz, Lawrence H., White, Keith S., Hanusik, Richard, Kessel, Sandra K., Morano, Karen, Laurie, Fran, and Bernier, Jacques, editor

Published
2011
Full Text
View/download PDF

22. Redesigning Radiotherapy Quality Assurance: Opportunities to Develop an Efficient, Evidence-Based System to Support Clinical Trials—Report of the National Cancer Institute Work Group on Radiotherapy Quality Assurance

Author

Bekelman, Justin E., Deye, James A., Vikram, Bhadrasain, Bentzen, Soren M., Bruner, Deborah, Curran, Walter J., Jr., Dignam, James, Efstathiou, Jason A., FitzGerald, T.J., Hurkmans, Coen, Ibbott, Geoffrey S., Lee, J. Jack, Merchant, Thomas E., Michalski, Jeff, Palta, Jatinder R., Simon, Richard, Ten Haken, Randal K., Timmerman, Robert, Tunis, Sean, Coleman, C. Norman, and Purdy, James

Published
2012
Full Text
View/download PDF

24. Past AAPM President: 1999.

Author

Ibbott, Geoffrey S

Subjects
*CORPORATE directors, *MEDICAL physics, *PROSPECTIVE payment systems, *PHYSICS education
Abstract

My term as the 40th President of the American Association of Physicists in Medicine (AAPM) began in January 1999. She raised the idea of encouraging participation by medical physicists on the CRCPD committees that develop model regulations (the Suggested State Regulations committees) to help their members understand new developments and anticipate future needs for regulatory guidance. I later learned that a large proportion of the letters (30%-40%) came from medical physicists, demonstrating the effectiveness of our campaign to educate our membership as well as the interest exhibited by medical physicists about the issue. [Extracted from the article]

Published
2023
Full Text
View/download PDF

31. Dosimetric, radiobiological and secondary cancer risk evaluation in head-and-neck three-dimensional conformal radiation therapy, intensity-modulated radiation therapy, and volumetric modulated arc therapy: A phantom study

Author

Rehman, Jalil Ur, Isa, Muhammad, Ahmad, Nisar, Nasar, Gulfam, Asghar, H. M. Noor Ul Huda Khan, Gilani, Zaheer Abbas, Chow, James C. L., Afzal, Muhammad, and Ibbott, Geoffrey S.

Subjects
volumetric modulated arc therapy, lcsh:Medical physics. Medical radiology. Nuclear medicine, EBT2 FILM, three-dimensional conformal radiation therapy, lcsh:R895-920, Technical Note, thermoluminescent dosimeter, imaging and radiation oncology core, intensity-modulated radiation therapy
Abstract

This analysis estimated secondary cancer risks after volumetric modulated arc therapy (VMAT) and compared those risks to the risks associated with other modalities of head-and-neck (H&N) radiotherapy. Images of H&N anthropomorphic phantom were acquired with a computed tomography scanner and exported via digital imaging and communications in medicine (DICOM) standards to a treatment planning system. Treatment plans were performed using a VMAT dual-arc technique, a nine-field intensity-modulated radiation therapy (IMRT) technique, and a four-field three-dimensional conformal therapy (3DCRT) technique. The prescription dose was 66.0 Gy for all three techniques, but to accommodate the range of dosimeter responses, we delivered a single dose of 6.60 Gy to the isocenter. The lifetime risk for secondary cancers was estimated according to National Council on Radiation Protection and Measurements (NCRP) Report 116. VMAT delivered the lowest maximum doses to esophagus (23 Gy), and normal brain (40 Gy). In comparison, maximum doses for 3DCRT were 74% and 40%, higher than those for VMAT for the esophagus, and normal brain, respectively. The normal tissue complication probability and equivalent uniform dose for the brain (2.1%, 0.9%, 0.8% and 3.8 Gy, 2.6 Gy, 2.3 Gy) and esophagus (4.2%, 0.7%, 0.4% and 3.7 Gy, 2.2 Gy, 1.8 Gy) were calculated for the 3DCRT, IMRT and VMAT respectively. Fractional esophagus OAR volumes receiving more than 20 Gy were 3.6% for VMAT, 23.6% for IMRT, and 100% for 3DCRT. The calculations for mean doses, NTCP, EUD and OAR volumes suggest that the risk of secondary cancer induction after VMAT is lower than after IMRT and 3DCRT.

Published
2018

50. International Conference on Advances in Radiation Oncology (ICARO): Outcomes of an IAEA Meeting

Author

Wondergem Jan, Zubizarreta Eduardo, Rosenblatt Eduardo, Joiner Michael C, Ibbott Geoffrey S, Kiel Krystyna, Salminen Eeva K, and Meghzifene Ahmed

Subjects
Medical physics. Medical radiology. Nuclear medicine, R895-920, Neoplasms. Tumors. Oncology. Including cancer and carcinogens, RC254-282
Abstract

Abstract The IAEA held the International Conference on Advances in Radiation Oncology (ICARO) in Vienna on 27-29 April 2009. The Conference dealt with the issues and requirements posed by the transition from conventional radiotherapy to advanced modern technologies, including staffing, training, treatment planning and delivery, quality assurance (QA) and the optimal use of available resources. The current role of advanced technologies (defined as 3-dimensional and/or image guided treatment with photons or particles) in current clinical practice and future scenarios were discussed. ICARO was organized by the IAEA at the request of the Member States and co-sponsored and supported by other international organizations to assess advances in technologies in radiation oncology in the face of economic challenges that most countries confront. Participants submitted research contributions, which were reviewed by a scientific committee and presented via 46 lectures and 103 posters. There were 327 participants from 70 Member States as well as participants from industry and government. The ICARO meeting provided an independent forum for the interaction of participants from developed and developing countries on current and developing issues related to radiation oncology.

Published
2011
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results