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Ashram S, Bahig H, Barry A, Blanchette D, Celinksi A, Chung P, Darko J, Donath D, Doucet R, Erickson A, Giuliani M, Gopaul D, Hipwell S, Javor J, Kuk J, Lindsay P, Millman B, Oliver M, Pearce A, Russell C, Senthi S, Vu T, Warner A, Gaede S, Palma DA. Planning Trade-offs for Stereotactic Ablative Radiotherapy in Patients with 4-10 Metastases: A Sub-study of the SABR-COMET-10 randomized trial. Int J Radiat Oncol Biol Phys 2022; 114:1011-1015. [PMID: 35667527 DOI: 10.1016/j.ijrobp.2022.05.035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 05/18/2022] [Accepted: 05/23/2022] [Indexed: 10/18/2022]
Abstract
BACKGROUND The use of stereotactic ablative radiotherapy (SABR) for metastases often involves trade-offs, balancing adequate target coverage with the need to maintain a safe dose to organs at risk (OARs). Very few studies have evaluated this complexity in patients with >3 oligometastases. To explore these trade-offs, we analyzed planning outcomes from the first 60 patients enrolled on a randomized trial of SABR in patients with 4-10 metastases. METHODS Radiation plans for patients enrolled on the BLINDED-FOR-REVIEW randomized trial were analyzed. Data abstracted included target locations and sizes, dose prescriptions and target coverage, and OAR doses, and these parameters were evaluated based on target location to identify locations where compromise of planning constraints was required. RESULTS SABR was planned for 332 lesions in 296 separate PTVs. The median PTV size was 9.0 cc per lesion (interquartile range [IQR]: 5.3-24.3 cc) and 89.1 cc per patient (IQR: 37.0-177.0). The most common prescriptions were 30-35 Gy in 5 fractions (43% of lesions) and 20-24 Gy in 1 fraction (33% of lesions). The maximum dose within the PTV was a median of 124% of prescription (IQR: 117-130%). Only 3.3% of lesions had a dose to 95% of the PTV (D95) <95% of prescription; this was more common for spinal (25%) and lymph node (8.4%) targets (p<0.001), translating to median D95 values of 100.5% (IQR: 99.6%-101.5%) and 100.0% (IQR: 84.6%-100.5%), respectively. All OARs constraints were met in 95.2% of patients, with the only exceptions being lymph node targets (n=3). CONCLUSIONS SABR planning for patients with 4-10 metastases was achievable without dosimetric compromise in the large majority of patients. Nodal and spinal targets were most likely to lead to compromise of target coverage or OAR constraints. Further research is needed to determine how to best balance these trade-offs.
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Affiliation(s)
- Samaher Ashram
- Department of Oncology, London Health Sciences Centre, London, Ontario, Canada
| | - Houda Bahig
- Centre Hospitalier de l'Université de Montréal, Montréal, Quebec, Canada
| | - Aisling Barry
- Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, Ontario, Canada; Department of Radiation Oncology, Toronto, Ontario, Canada
| | | | - Anders Celinksi
- Department of Oncology, London Health Sciences Centre, London, Ontario, Canada
| | - Peter Chung
- Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, Ontario, Canada; Department of Radiation Oncology, Toronto, Ontario, Canada
| | - Johnson Darko
- Grand River Cancer Centre, Kitchener, Ontario, Canada
| | - David Donath
- Centre Hospitalier de l'Université de Montréal, Montréal, Quebec, Canada
| | - Robert Doucet
- Centre Hospitalier de l'Université de Montréal, Montréal, Quebec, Canada
| | - Abigail Erickson
- Department of Oncology, London Health Sciences Centre, London, Ontario, Canada
| | - Meredith Giuliani
- Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, Ontario, Canada; Department of Radiation Oncology, Toronto, Ontario, Canada
| | - Darin Gopaul
- Grand River Cancer Centre, Kitchener, Ontario, Canada
| | - Scott Hipwell
- Department of Oncology, London Health Sciences Centre, London, Ontario, Canada
| | - Joanna Javor
- Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, Ontario, Canada; Department of Radiation Oncology, Toronto, Ontario, Canada
| | - Joda Kuk
- Grand River Cancer Centre, Kitchener, Ontario, Canada
| | - Patricia Lindsay
- Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, Ontario, Canada; Department of Radiation Oncology, Toronto, Ontario, Canada
| | - Barbara Millman
- Department of Oncology, London Health Sciences Centre, London, Ontario, Canada
| | | | | | | | | | - Toni Vu
- Centre Hospitalier de l'Université de Montréal, Montréal, Quebec, Canada
| | - Andrew Warner
- Department of Oncology, London Health Sciences Centre, London, Ontario, Canada
| | - Stewart Gaede
- Department of Oncology, London Health Sciences Centre, London, Ontario, Canada
| | - David A Palma
- Department of Oncology, London Health Sciences Centre, London, Ontario, Canada.
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Poirier VJ, Koh ESY, Darko J, Fleck A, Pinard C, Vail DM. Patterns of local residual disease and local failure after intensity modulated/image guided radiation therapy for sinonasal tumors in dogs. J Vet Intern Med 2021; 35:1062-1072. [PMID: 33660342 PMCID: PMC7995431 DOI: 10.1111/jvim.16076] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 02/03/2021] [Accepted: 02/04/2021] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Most dogs with sinonasal tumors (SNT) treated with radiation therapy (RT) died because of local disease progression. HYPOTHESIS/OBJECTIVES Our hypothesis is that the majority of local failure and residual disease would occur within the radiation field. ANIMALS Twenty-two dogs with SNT treated with RT. METHODS Retrospective cohort study. INCLUSION CRITERIA dogs with SNT receiving 10 daily fractions of 4.2 Gy with intensity modulated radiation therapy (IMRT)/image guided radiation therapy (IGRT) and follow-up cone beam computed tomography (CBCT). Each CBCT was registered with the original radiation planning CT and the gross tumor volume (GTV) contoured. The GTV was classified as residual (GTVr) or a failure (GTVf). The dose statistic for each GTV was calculated with the original IMRT plan. For GTVf, failures were classified as "in-field," "marginal," or "out-field" if at least 95, 20-95, or less than 20% of the volume of failure was within 95% (D95) of the total prescription dose, respectively. RESULTS There were 52 follow-up CBCT/CTs. Overall there was a GTVr for 20 dogs and GTVf for 16 dogs. The majority of GTVr volume was within the original GTV. GTVf analysis showed that 75% (12/16) were "in-field," 19% (3/16) were "marginal" and 6% (1/16) were "out-field." CONCLUSION AND CLINICAL IMPORTANCE In-field failures are the main pattern for local recurrence, and there is evidence of radioresistant subvolumes within the GTV.
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Affiliation(s)
- Valerie J Poirier
- School of Veterinary Science, Massey University, Palmerston North, New Zealand.,Department of clinical studies, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
| | - Ethel S Y Koh
- School of Veterinary Science, Massey University, Palmerston North, New Zealand
| | - Johnson Darko
- Department of Medical Physics, Grand River Regional Cancer Centre, Kitchener, Ontario, Canada
| | - Andre Fleck
- Department of Medical Physics, Grand River Regional Cancer Centre, Kitchener, Ontario, Canada
| | - Christopher Pinard
- Department of clinical studies, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
| | - David M Vail
- School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA
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Poirier VJ, Matsuyama A, Kim C, Darko J, Fleck A. Clinical-dosimetric relationship between lacrimal gland dose and keratoconjunctivitis sicca in dogs with sinonasal tumors treated with radiation therapy. J Vet Intern Med 2020; 34:867-872. [PMID: 32086981 PMCID: PMC7096656 DOI: 10.1111/jvim.15744] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2019] [Revised: 02/10/2020] [Accepted: 02/14/2020] [Indexed: 12/25/2022] Open
Abstract
Background Dogs with sinonasal tumor can develop keratoconjunctivitis sicca (KCS) after radiation therapy (RT). In humans, the incidence of xerophtalmia is associated with the mean radiation dose received by the ipsilateral lacrimal gland (LG). Hypothesis/Objectives The eyes receiving a higher mean LG dose are more likely to develop KCS. The aim of the study was to determine a starting threshold dose to use as dose constraint for intensity‐modulated radiation therapy (IMRT). Animals Dogs with nasal tumors treated with RT between August 2013 and December 2016. Methods Case control retrospective study of dogs with sinonasal tumor treated with 42 Gray (Gy) in 10 fractions using IMRT. Dogs were included if development of KCS after RT was documented (cases) or adequate follow‐up information with Schirmer tear test (STT) result for ≥6 months after RT was available (controls). Lacrimal glands were contoured and dose distribution was calculated using the original treatment plan to determine prescribed doses to LGs. Results Twenty‐five dogs were treated with RT and 5 dogs (20%) developed KCS. Fifteen dogs met the inclusion criteria including 5 unilateral KCS and 10 control dogs, resulting in 5 KCS eyes and 25 control eyes. KCS developed at a median of 111 days (84‐122) after 1st RT. The mean LG dose reached using a 4.2 Gy per fraction was 33.08 Gy (range: 23.75‐42.33) for KCS eyes and 10.33 Gy (1.8‐24.77) for control eyes (P < .001). The minimum LG mean dose for developing KCS was 23.75 Gy. No eyes that received a mean LG dose <20 Gy developed KCS versus 5/7 (71%) developed with >20 Gy. Conclusion and Clinical Importance Contouring and applying a dose constraint on LGs should be performed when using IMRT in dogs with sinonasal tumors to reduce the risk of KCS.
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Affiliation(s)
- Valerie J Poirier
- School of Veterinary Science, Massey University, Palmerston North, New Zealand.,Animal Cancer Centre, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
| | - Arata Matsuyama
- Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
| | - Changseok Kim
- Animal Cancer Centre, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
| | - Johnson Darko
- Department of Medical Physics, Grand River Regional Cancer Centre, Kitchener, Ontario, Canada
| | - Andre Fleck
- Department of Medical Physics, Grand River Regional Cancer Centre, Kitchener, Ontario, Canada
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Grigorov G, Chow JC, Bauman G, Darko J, Kiciak A, Osei E. A Novel 2D Probability Density Function Integrating the Rectal Motion and Wall Thickness in Prostate IMRT. J Med Imaging Radiat Sci 2019; 50:488-498. [DOI: 10.1016/j.jmir.2019.09.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 09/03/2019] [Accepted: 09/05/2019] [Indexed: 11/26/2022]
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Osei B, Xu L, Johnston A, Darko S, Darko J, Osei E. Retrospective study of patients radiation dose during cardiac catheterization procedures. Br J Radiol 2019; 92:20181021. [PMID: 31045448 PMCID: PMC6636266 DOI: 10.1259/bjr.20181021] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 04/19/2019] [Accepted: 04/24/2019] [Indexed: 01/19/2023] Open
Abstract
OBJECTIVE Cardiac catheterization procedures provide tremendous benefits to modern healthcare and the benefit derived by the patient should far outweigh the radiation risk associated with a properly optimized procedure. With increasing utilization of such procedures, there is growing concern regarding the magnitude and variations of dose to patients associated with procedure complexity and techniques parameters. Therefore, this study investigated radiation dose to patients from six cardiac catheterization procedures at our facility and suggest possible initial dose values for benchmark for patient radiation dose from these procedures. This initial benchmark data will be used for clinical radiation dose management which is essential for assessing the impact of any quality improvement initiatives in the cardiac catheterization laboratory. METHODS We retrospectively analyzed the dose parameters of 1000 patients who underwent various cardiac catheterization procedures: left heart catheterization (LH), percutaneous coronary intervention (PCI), complex PCI, LH with complex PCI, LH with PCI and cardiac resynchronization therapy (CRT) pacemaker in our cardiac catheterization laboratories. Patient's clinical radiation dose data [kerma-area-product (KAP) and air-kerma at the interventional reference point (Ka,r)] and technique parameters (fluoroscopy time, tube potential, current, pulse width and number of cine images) along with demographic information (age, height and weight) were collected from the hospital's RIS (Synapse), Sensis/Syngo Dynamics and Siemens Sensis Stats Manager electronic database. Statistical analysis was performed with the IBM SPSS Modeler v. 18.1 software. RESULTS The overall patient median age was 67.0 (range: 26.0-97.0) years and the median body mass index (BMI) was 28.8 (range: 15.9-61.7) kg/m2 . The median KAP for the LH, PCI, LH with complex PCI, complex PCI, LH with PCI and CRT-pacemaker procedures are 44.4 (4.1-203.2), 80.2 (18.9-208.5), 83.7 (48.0-246.1), 113.8 (60.9-284.5), 91.7 (6.0-426.0) and 51.1 (7.0-175.9) Gy-cm2 . The median Ka,r for the LH, PCI, LH with complex PCI, complex PCI, LH with PCI and CRT-pacemaker procedures are 701.0 (35.3-3794.0), 1384.7 (291.7-4021.8), 1607.0 (883.5-4448.3), 2260.2 (867.4-5311.9), 1589.3 (100.2-7237.4) and 463.8 (67.7-1695.9) mGy respectively. CONCLUSION We have analyzed patient radiation doses from six commonly used procedures in our cardiac catheterization laboratories and suggested possible initial values for benchmark from these procedures for the fluoroscopy time, KAP and air-kerma at the interventional reference point based on our current practices. Our data compare well with published values reported in the literature by investigators who have also studied patient doses and established benchmark dose levels for their facilities. Procedure-specific benchmark dose data for various groups of patients can provide the motivation for monitoring practices to promote improvements in patient radiation dose optimization in the cardiac catheterization laboratories. ADVANCES IN KNOWLEDGE We have investigated local patients' radiation doses and established benchmark radiation data which are essential for assessing the impact of any quality improvement initiatives for radiation dose optimization.
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Affiliation(s)
| | | | | | - Sara Darko
- Department of Clinical Trials, Grand River Regional Cancer Centre, Kitchener, ON, Canada
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Aborig M, Malik PRV, Nambiar S, Chelle P, Darko J, Mutsaers A, Edginton AN, Fleck A, Osei E, Wettig S. Biodistribution and Physiologically-Based Pharmacokinetic Modeling of Gold Nanoparticles in Mice with Interspecies Extrapolation. Pharmaceutics 2019; 11:E179. [PMID: 31013763 PMCID: PMC6523871 DOI: 10.3390/pharmaceutics11040179] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 04/04/2019] [Accepted: 04/10/2019] [Indexed: 12/30/2022] Open
Abstract
Gold nanoparticles (AuNPs) are a focus of growing medical research applications due to their unique chemical, electrical and optical properties. Because of uncertain toxicity, "green" synthesis methods are emerging, using plant extracts to improve biological and environmental compatibility. Here we explore the biodistribution of green AuNPs in mice and prepare a physiologically-based pharmacokinetic (PBPK) model to guide interspecies extrapolation. Monodisperse AuNPs were synthesized and capped with epigallocatechin gallate (EGCG) and curcumin. 64 CD-1 mice received the AuNPs by intraperitoneal injection. To assess biodistribution, groups of six mice were sacrificed at 1, 7, 14, 28 and 56 days, and their organs were analyzed for gold content using inductively coupled plasma mass spectrometry (ICP-MS). A physiologically-based pharmacokinetic (PBPK) model was developed to describe the biodistribution data in mice. To assess the potential for interspecies extrapolation, organism-specific parameters in the model were adapted to represent rats, and the rat PBPK model was subsequently evaluated with PK data for citrate-capped AuNPs from literature. The liver and spleen displayed strong uptake, and the PBPK model suggested that extravasation and phagocytosis were key drivers. Organ predictions following interspecies extrapolation were successful for rats receiving citrate-capped AuNPs. This work lays the foundation for the pre-clinical extrapolation of the pharmacokinetics of AuNPs from mice to larger species.
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Affiliation(s)
- Mohamed Aborig
- School of Pharmacy, University of Waterloo, Kitchener, ON N2G 1C5, Canada.
| | - Paul R V Malik
- School of Pharmacy, University of Waterloo, Kitchener, ON N2G 1C5, Canada.
| | - Shruti Nambiar
- School of Pharmacy, University of Waterloo, Kitchener, ON N2G 1C5, Canada.
| | - Pierre Chelle
- School of Pharmacy, University of Waterloo, Kitchener, ON N2G 1C5, Canada.
| | - Johnson Darko
- Grand River Regional Cancer Centre, Grand River Hospital, Kitchener, ON N2G 1G3, Canada.
- Department of Physics and Astronomy, University of Waterloo, Waterloo, ON N2L 3G1, Canada.
- Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada.
| | - Anthony Mutsaers
- Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada.
| | - Andrea N Edginton
- School of Pharmacy, University of Waterloo, Kitchener, ON N2G 1C5, Canada.
| | - Andre Fleck
- Grand River Regional Cancer Centre, Grand River Hospital, Kitchener, ON N2G 1G3, Canada.
- Department of Systems Design Engineering, University of Waterloo, Waterloo, ON N2L 3G1, Canada.
| | - Ernest Osei
- Grand River Regional Cancer Centre, Grand River Hospital, Kitchener, ON N2G 1G3, Canada.
- Department of Physics and Astronomy, University of Waterloo, Waterloo, ON N2L 3G1, Canada.
- Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada.
- Department of Systems Design Engineering, University of Waterloo, Waterloo, ON N2L 3G1, Canada.
| | - Shawn Wettig
- School of Pharmacy, University of Waterloo, Kitchener, ON N2G 1C5, Canada.
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Jafry Z, Gal A, Fleck A, Darko J, Poirier VJ. Proposed expansion margins for planning organ at risk volume for lenses during radiation therapy of the nasal cavity in dogs and cats. Vet Radiol Ultrasound 2017; 58:471-478. [PMID: 28397316 DOI: 10.1111/vru.12490] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2016] [Revised: 12/08/2016] [Accepted: 12/20/2016] [Indexed: 12/25/2022] Open
Abstract
Radiation therapy protocols for the feline or canine nasal cavity can damage epithelial cells of the posterior pole of the lens and lead to the development of cataracts. Aims of this retrospective, descriptive study were to calculate movements of the lens during radiation therapy of the nasal cavity in a sample of cats and dogs, and to propose species-specific expansion margins for planning organ at risk volume (PRV) to minimize radiation doses to the lens. All included patients were immobilized with an indexed bite block and positioned in a vacuum positioning cushion for head irradiation. On-board cone beam CT (CBCT) imaging was used for patient alignment. Both ocular lenses were contoured on the therapeutic CBCTs. Coregistration (fusion) between the planning CT and CBCTs was used to measure the movements of the lens. Two measurements were made: the differences between the centroid point of each lens as well as the displacement of the coregistrations. A total of 496 different observations were recorded from 14 cats and 52 dogs. Using the displacement results, we calculated how often the lens would be within the lens-PRV contour. We proposed that an optimal expansion margin from the lens volume of 2 mm in cats and 3 mm in dogs may be necessary in generating PRV expansion for the lens. From our results, we expect the lens would therefore be within these proposed PRV expansions in 92% of the feline measurements and 95% of the canine measurements.
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Affiliation(s)
- Zaki Jafry
- Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, 4474, New Zealand
| | - Arnon Gal
- Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, 4474, New Zealand
| | - Andre Fleck
- Department of Medical Physics, Grand River Regional Cancer Centre, Kitchener, ON, N2G 1G3, Canada
| | - Johnson Darko
- Department of Medical Physics, Grand River Regional Cancer Centre, Kitchener, ON, N2G 1G3, Canada
| | - Valerie J Poirier
- Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, 4474, New Zealand.,Animal Cancer Centre, Ontario Veterinary College, University of Guelph, Guelph, N1G 2W1, Ontario, Canada
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Liu B, Darko J, Osei E. Poster - 56: Preliminary comparison of FF- and FFF-VMAT for prostate plans with higher rectal dose. Med Phys 2016. [DOI: 10.1118/1.4961830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Badu S, Darko J, Fleck A, Osei E. Poster - 22: Retrospective analysis of portal dosimetry based QA of Prostate VMAT Plans. Med Phys 2016. [DOI: 10.1118/1.4961796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Darko J, Kiciak A, Badu S, Grigorov G, Fleck A, Osei E. SU-F-T-272: Patient Specific Quality Assurance of Prostate VMAT Plans with Portal Dosimetry. Med Phys 2016. [DOI: 10.1118/1.4956412] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Osei E, Darko J, Fleck A, White J, Kiciak A, Redekop R, Gopaul D. Dosimetric evaluation of whole-breast radiation therapy: clinical experience. Med Dosim 2015; 40:355-65. [PMID: 26119108 DOI: 10.1016/j.meddos.2015.05.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 04/15/2015] [Accepted: 05/09/2015] [Indexed: 01/28/2023]
Abstract
Radiation therapy of the intact breast is the standard therapy for preventing local recurrence of early-stage breast cancer following breast conservation surgery. To improve patient standard of care, there is a need to define a consistent and transparent treatment path for all patients that reduces significance variations in the acceptability of treatment plans. There is lack of consistency among institutions or individuals about what is considered an acceptable treatment plan: target coverage vis-à-vis dose to organs at risk (OAR). Clinical trials usually resolve these issues, as the criteria for an acceptable plan within the trial (target coverage and doses to OAR) are well defined. We developed an institutional criterion for accepting breast treatment plans in 2006 after analyzing treatment data of approximately 200 patients. The purpose of this article is to report on the dosimetric review of 623 patients treated in the last 18 months to evaluate the effectiveness of the previously developed plan acceptability criteria and any possible changes necessary to further improve patient care. The mean patient age is 61.6 years (range: 25.2 to 93.0 years). The mean breast separation for all the patients is 21.0cm (range: 12.4 to 34.9cm), and the mean planning target volume (PTV_eval) (breast volume for evaluation) is 884.0cm(3) (range: 73.6 to 3684.6cm(3)). Overall, 314 (50.4%) patients had the disease in the left breast and 309 (49.6%) had it in the right breast. A total of 147 (23.6%) patients were treated using the deep inspiration breath-hold (DIBH) technique. The mean normalized PTV_eval receiving at least 92% (V92% PD) and 95% (V95% PD) of the prescribed dose (PD) are more than 99% and 97%, respectively, for all patients. The mean normalized PTV_eval receiving at least 105% (V105% PD) of the PD is less than 1% for all groups. The mean homogeneity index (HI), uniformity index (UI), and conformity index (CI) for the PTV_eval are 0.09 (range: 0.05 to 0.15), 1.07 (range: 0.46 to 1.11), and 0.98 (range: 0.92 to 1.0), respectively. Our data confirm the significant advantage of using DIBH to reduce heart dose when compared with the free-breathing technique. The p values analyses of the results for the V5Gy, V10Gy, V15Gy, V20Gy, and V30Gy for the heart comparing DIBH and free-breathing techniques are well less than 0.05 (i.e., p < 0.05). However, similar analyses for the lung give values greater than 0.05 (i.e., p > 0.05), indicating that there is no significant difference in lung dose comparing the 2 treatment techniques.
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Affiliation(s)
- Ernest Osei
- Department of Medical Physics, Grand River Regional Cancer Centre, Kitchener, Ontario, Canada; Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, Canada; Department of Systems Design, University of Waterloo, Waterloo, Ontario, Canada.
| | - Johnson Darko
- Department of Medical Physics, Grand River Regional Cancer Centre, Kitchener, Ontario, Canada; Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, Canada
| | - Andre Fleck
- Department of Medical Physics, Grand River Regional Cancer Centre, Kitchener, Ontario, Canada
| | - Jana White
- Department of Radiation Therapy, Grand River Regional Cancer Centre, Kitchener, Ontario, Canada
| | - Alexander Kiciak
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, Canada
| | - Rachel Redekop
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, Canada
| | - Darin Gopaul
- Department of Radiation Oncology, Grand River Regional Cancer Centre, Kitchener, Ontario, Canada
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Grigorov G, Darko J, Kitor M, Redekop R, Osei E. SU-E-T-100: An Approach to Improving the Dynamic Delivery Accuracy for Breast IMRT. Med Phys 2015. [DOI: 10.1118/1.4924461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Dhanesar S, Darko J, Joshi CP, Kerr A, John Schreiner L. Cobalt-60 tomotherapy: Clinical treatment planning and phantom dose delivery studies. Med Phys 2013; 40:081710. [DOI: 10.1118/1.4812417] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Dhanesar S, Darko J, Schreiner L. SU-E-T-558: Photon Fluence Model for Distributed Radiation Sources Using the Convolution Method. Med Phys 2013. [DOI: 10.1118/1.4814987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Osei EK, Darko J. Foetal radiation dose and risk from diagnostic radiology procedures: a multinational study. ISRN Radiol 2012; 2013:318425. [PMID: 24959554 PMCID: PMC4045527 DOI: 10.5402/2013/318425] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Accepted: 07/08/2012] [Indexed: 11/23/2022]
Abstract
In diagnostic radiology examinations there is a benefit that the patient derives from the resulting diagnosis. Given that so many examinations are performed each year, it is inevitable that there will be occasions when an examination(s) may be inadvertently performed on pregnant patients or occasionally it may become clinically necessary to perform an examination(s) on a pregnant patient. In all these circumstances it is necessary to request an estimation of the foetal dose and risk. We initiated a study to investigate fetal doses from different countries. Exposure techniques on 367 foetuses from 414 examinations were collected and investigated. The FetDoseV4 program was used for all dose and risk estimations. The radiation doses received by the 367 foetuses ranges: <0.001-21.9 mGy depending on examination and technique. The associated probability of induced hereditary effect ranges: <1 in 200000000 (5 × 10(-9)) to 1 in 10000 (1 × 10(-4)) and the risk of childhood cancer ranges <1 in 12500000 (8 × 10(-8)) to 1 in 500 (2 × 10(-3)). The data indicates that foetal doses from properly conducted diagnostic radiology examinations will not result in any deterministic effect and a negligible risk of causing radiation induced hereditary effect in the descendants of the unborn child.
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Affiliation(s)
- Ernest K. Osei
- Department of Medical Physics, Grand River Regional Cancer Center, Kitchener, Canada N2G 1G3
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Canada N2L 3G1
| | - Johnson Darko
- Cancer Center of Southeastern Ontario, Kingston General Hospital, Kingston, Canada K7L 5P9
- Department of Oncology, Queens University, Kingston, Canada K7L 5P9
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Osei EK, Darko J. A survey of organ equivalent and effective doses from diagnostic radiology procedures. ISRN Radiol 2012; 2013:204346. [PMID: 24977137 PMCID: PMC4045519 DOI: 10.5402/2013/204346] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Accepted: 07/10/2012] [Indexed: 11/23/2022]
Abstract
The quantification of radiation risks associated with radiological examinations has been a subject of interest with the increased use of X-rays. Effective dose, which is a risk-weighted measure of radiation to organs in the body associated with radiological examination, is considered a good indicator of radiological risk. We have therefore investigated patient effective doses from radiological examinations. Organ and effective doses were estimated for 94 patients who underwent computed tomography examinations and for 338 patients who had conventional radiography examinations. The OrgDose (version 2) program was used for the estimation of effective doses. The tube potential ranges: 57 kVp to 138 kVp depending on the examination and patient size. The entrance surface doses have a wide range even for the same examination: 0.44-10.31 mGy (abdomen) and 0.66-16.08 mGy (lumbar spine) and the corresponding effective dose ranges 0.025-0.77 mSv and 0.025-0.95 mSv respectively. Effective dose for adult abdomen-pelvic CT examinations ranges 5.4-19.8 mSv with a mean of 13.6 mSv and for pediatrics ranges 2.1-5.5 mSv with a mean of 2.7 mSv. The mean effective dose for adult chest and head CT examinations are 7.9 and 1.8 mSv respectively and for pediatrics are 1.7 and 1.1 mSv.
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Affiliation(s)
- Ernest K. Osei
- Department of Medical Physics, Grand River Regional Cancer Center, Kitchener, ON, Canada N2G 1G3
- Department of Physics and Astronomy, University of Waterloo, Waterloo, ON, Canada N2L 3G1
| | - Johnson Darko
- Cancer Center of Southeastern Ontario, Kingston General Hospital, Kingston, ON, Canada K7L 5P9
- Department of Oncology, Queens University, Kingston, ON, Canada K7L 5P9
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Dhanesar S, Darko J, Schreiner LJ. Aperture superposition dose model versus pencil beam superposition dose model for a finite size Cobalt-60 source for tomotherapy deliveries. Med Phys 2011; 39:206-13. [DOI: 10.1118/1.3665706] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Joshi CP, Darko J, Vidyasagar PB, Schreiner LJ. Dosimetry of interface region near closed air cavities for Co-60, 6 MV and 15 MV photon beams using Monte Carlo simulations. J Med Phys 2011; 35:73-80. [PMID: 20589116 PMCID: PMC2884308 DOI: 10.4103/0971-6203.62197] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2009] [Revised: 10/17/2009] [Accepted: 11/14/2009] [Indexed: 11/25/2022] Open
Abstract
Underdosing of treatment targets can occur in radiation therapy due to electronic disequilibrium around air-tissue interfaces when tumors are situated near natural air cavities. These effects have been shown to increase with the beam energy and decrease with the field size. Intensity modulated radiation therapy (IMRT) and tomotherapy techniques employ combinations of multiple small radiation beamlets of varying intensities to deliver highly conformal radiation therapy. The use of small beamlets in these techniques may therefore result in underdosing of treatment target in the air-tissue interfaces region surrounding an air cavity. This work was undertaken to investigate dose reductions near the air-water interfaces of 1×1×1 and 3×3×3 cm3 air cavities, typically encountered in the treatment of head and neck cancer utilizing radiation therapy techniques such as IMRT and tomotherapy using small fields of Co-60, 6 MV and 15 MV photons. Additional investigations were performed for larger photon field sizes encompassing the entire air-cavity, such as encountered in conventional three dimensional conformal radiation therapy (3DCRT) techniques. The EGSnrc/DOSXYZnrc Monte Carlo code was used to calculate the dose reductions (in water) in air-water interface region for single, parallel opposed and four field irradiations with 2×2 cm2 (beamlet), 10×2 cm2 (fan beam), 5×5 and 7×7 cm2 field sizes. The magnitude of dose reduction in water near air-water interface increases with photon energy; decreases with distance from the interface as well as decreases as the number of beams are increased. No dose reductions were observed for large field sizes encompassing the air cavities. The results demonstrate that Co-60 beams may provide significantly smaller interface dose reductions than 6 MV and 15 MV irradiations for small field irradiations such as used in IMRT and tomotherapy.
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Affiliation(s)
- Chandra P Joshi
- Cancer Centre of South Eastern Ontario at Kingston General Hospital, 25 King Street West, Kingston, ON, K7L5P9, Canada
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Joshi CP, Dhanesar S, Darko J, Kerr A, Vidyasagar PB, Schreiner LJ. Practical and clinical considerations in Cobalt-60 tomotherapy. J Med Phys 2011; 34:137-40. [PMID: 20098560 PMCID: PMC2807678 DOI: 10.4103/0971-6203.54847] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2009] [Revised: 02/19/2009] [Accepted: 04/01/2009] [Indexed: 12/04/2022] Open
Abstract
Cobalt-60 (Co-60) based radiation therapy continues to play a significant role in not only developing countries, where access to radiation therapy is extremely limited, but also in industrialized countries. Howver, technology has to be developed to accommodate modern techniques, including image guided and adaptive radiation therapy (IGART). In this paper we describe some of the practical and clinical considerations for Co-60 based tomotherapy by comparing Co-60 and 6 MV linac-based tomotherapy plans for a head and neck (HandN) cancer and a prostate cancer case. The tomotherapy IMRT plans were obtained by modeling a MIMiC binary multi-leaf collimator attached to a Theratron-780c Co-60 unit and a 6 MV linear accelerator (CL2100EX). The EGSnrc/BEAMnrc Monte Carlo (MC) code was used for the modeling of the treatment units with the MIMiC collimator and EGSnrc/DOSXYZnrc code was used for beamlet dose data. An in-house inverse treatment planning program was then used to generate optimized tomotherapy dose distributions for the H and N and prostate cases. The dose distributions, cumulative dose area histograms (DAHs) and dose difference maps were used to evaluate and compare Co-60 and 6 MV based tomotherapy plans. A quantitative analysis of the dose distributions and dose-volume histograms shows that both Co-60 and 6 MV plans achieve the plan objectives for the targets (CTV and nodes) and OARs (spinal cord in HandN case, and rectum in prostate case).
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Affiliation(s)
- Chandra P Joshi
- Department of Medical Physics, Cancer Centre of Southeastern Ontario (CCSEO), Kingston, ON, Canada
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Schreiner LJ, Joshi CP, Darko J, Kerr A, Salomons G, Dhanesar S. The role of Cobalt-60 in modern radiation therapy: Dose delivery and image guidance. J Med Phys 2011; 34:133-6. [PMID: 20098559 PMCID: PMC2807677 DOI: 10.4103/0971-6203.54846] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2009] [Revised: 03/23/2009] [Accepted: 04/11/2009] [Indexed: 11/16/2022] Open
Abstract
The advances in modern radiation therapy with techniques such as intensity-modulated radiation therapy and image-guided radiation therapy (IMRT and IGRT) have been limited almost exclusively to linear accelerators. Investigations of modern Cobalt-60 (Co-60) radiation delivery in the context of IMRT and IGRT have been very sparse, and have been limited mainly to computer-modeling and treatment-planning exercises. In this paper, we report on the results of experiments using a tomotherapy benchtop apparatus attached to a conventional Co-60 unit. We show that conformal dose delivery is possible and also that Co-60 can be used as the radiation source in megavoltage computed tomography imaging. These results complement our modeling studies of Co-60 tomotherapy and provide a strong motivation for continuing development of modern Cobalt-60 treatment devices.
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Affiliation(s)
- L John Schreiner
- Department of Medical Physics, Cancer Centre of Southeastern Ontario (CCSEO), Kingston, ON, Canada
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Kerr A, Halsall T, Olding T, Schreiner LJ, Darko J. SU-E-T-78: Evaluation of IMRT QA Methods Using a Configurational Cylindrical Phantom. Med Phys 2011. [DOI: 10.1118/1.3612029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Dhanesar S, Darko J, Schreiner LJ. SU-E-T-745: Convolution-Superposition Model for Photon Dose Calculations of Finite Size Cobalt-60 Radiation Source. Med Phys 2011. [DOI: 10.1118/1.3612709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Kerr A, Rawluk N, MacDonald A, Marsh M, Schreiner J, Darko J. Cobalt-60 Source Based Image Guidance in Broad Beam Cobalt-60 IMRT. Int J Radiat Oncol Biol Phys 2010. [DOI: 10.1016/j.ijrobp.2010.07.1627] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Rawluk N, MacDonald A, Marsh M, Schreiner LJ, Darko J, Kerr A. Sci-Fri PM: Delivery - 10: Imaging Developments for Broad Beam Co-60 Radiation Therapy. Med Phys 2010. [DOI: 10.1118/1.3476198] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Dhanesar S, Darko J, Schreiner LJ. Sci-Thur PM: YIS - 04: Aperture Superposition Algorithm for Photon Dose Calculations of Finite Size Cobalt-60 Radiation Source for Tomotherapy Dose Deliveries. Med Phys 2010. [DOI: 10.1118/1.3476099] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Dhanesar SK, Darko J, Joshi CP, Kerr A, Schreiner LJ. SU-EE-A1-06: A Comparative Study of Cobalt-60 Based Tomotherapy versus 6 MV Linac-Based Tomotherapy, IMRT, and 3DCRT for the Treatment Planning of Prostate and Head and Neck Cases. Med Phys 2010. [DOI: 10.1118/1.3468011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Salomons G, Darko J. WE-E-BRA-04: The Effect of Smoothing on the Uncertainty in the Dose Distributions for a Commercial Electron Monte Carlo Algorithm. Med Phys 2010. [DOI: 10.1118/1.3469426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Olding T, Darko J, Schreiner LJ. Sci-Wed PM: Delivery-10: Optical CT-based Gel Dosimetry in Image Guided Adaptive Radiation Therapy. Med Phys 2009. [DOI: 10.1118/1.3244102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Grant J, Dhanesar S, Joshi C, Darko J, Schreiner LJ, Kerr A. Poster - Wed Eve-34: Design of a Primary Collimator for Cone Beam CT Imaging. Med Phys 2009. [DOI: 10.1118/1.3244138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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MacDonald A, Darko J, Schreiner LJ. Poster - Wed Eve-56: Megavoltage Digital Tomosynthesis Using a Radioactive Cobalt-60 Gamma Ray Source for Radiation Therapy Treatment Verification. Med Phys 2009. [DOI: 10.1118/1.3244160] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Holmes O, Darko J, Dhanesar S, Olding T, Schreiner LJ. Poster - Thurs Eve-42: A revision of the γ-evaluation: Initial interpretation of dose disagreements on γ-vector fields. Med Phys 2008; 35:3409. [PMID: 28512884 DOI: 10.1118/1.2965961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Gamma evaluations are a common clinical tool used as a quantitative comparison between dose-distributions, combining both dose difference and distance to agreement criteria. Because gamma evaluations permit rapid analysis of agreement between complex dose distributions, they are often a preferred comparison method for assessing delivery of conformal radiotherapy distributions. Although the comparison provides a useful measure of agreement between distributions when the index is less than one, the scalar gamma value provides little information into the clinical significance or source of disagreements of failing gamma values (i.e., when γ>1). Previously, Stock et al., have presented the gamma angle as an indicator of the relative influence of the distance to agreement versus the dose difference on gamma. We present a modification to the gamma evaluation such that the complete 3D gamma vector information is considered. The predictive nature of each vector component was investigated by simulating various dose disagreements in test distributions. Misalignment tests revealed that the mean gamma vector components indicate the offset direction and relative magnitude for all test distributions. The mean dose component of the gamma vector was prognostic of double Gaussian overdoses and underdoses in a virtual conformal delivery. The response of the vector field depends on properties distinctive to each distribution, such as the local dose gradient. Understanding how these unique properties affect the vector field may permit better diagnosis of dose disagreement sources. Other vector field properties, such as curl and divergence, may yet provide more information for interpreting the cause and significance of γ>1.
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Affiliation(s)
- O Holmes
- Departments of Physics and Oncology, Queen's University, Kingston, ON, Canada
| | - J Darko
- Medical Physics Department, Cancer Centre of Southeastern Ontario, Kingston, ON
| | - S Dhanesar
- Departments of Physics and Oncology, Queen's University, Kingston, ON, Canada
| | - T Olding
- Departments of Physics and Oncology, Queen's University, Kingston, ON, Canada
| | - L J Schreiner
- Departments of Physics and Oncology, Queen's University, Kingston, ON, Canada.,Medical Physics Department, Cancer Centre of Southeastern Ontario, Kingston, ON
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Dhanesar SK, Darko J, Joshi CP, Kerr AT, Schreiner LJ. Poster - Thurs Eve-15: Comparison of Cobalt-60 and 6 MV linac based tomotherapy: A prostate case study. Med Phys 2008; 35:3404. [DOI: 10.1118/1.2965934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Joshi CP, Darko J, Vidyasagar PB, Schreiner LJ. Investigation of an efficient source design for Cobalt-60-based tomotherapy using EGSnrc Monte Carlo simulations. Phys Med Biol 2008; 53:575-92. [DOI: 10.1088/0031-9155/53/3/005] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Joshi CP, Darko J, Dhanesar SK, Vidyasagar PB, Schreiner LJ. TH-C-AUD-08: Comparison of Tomotherapy Dose Distributions for 6MV X-Rays and Different Cobalt-60 Source Designs Using Monte Carlo Methods. Med Phys 2007. [DOI: 10.1118/1.2761667] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Schreiner L, Darko J, Joshi C, Rogers M, Chng N, Peters C, Salomons G, Kerr A. SU-DD-A1-01: Advances in Co-60 Based Tomotherapy Including Megavoltage CT. Med Phys 2006. [DOI: 10.1118/1.2240129] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Osei E, Fan C, Jeevasagayam G, Alexander A, Seguin M, Darko J. Po-Thur Eve General-12: ProLoc: An image-guided localization software for target positioning. Med Phys 2006. [DOI: 10.1118/1.2244639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Osei E, Bradley B, Fleck A, Darko J. Po-Thur Eve General-34: Normalized data for the estimation of fetal radiation dose from radiotherapy of the breast. Med Phys 2006. [DOI: 10.1118/1.2244661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Darko J, Joshi C, Osei E, Halsall T, Salomons G, Kerr A. Po-Thur Eve General-07: Dosimetry of Small Lung Lesions with EGSnrc Monte Carlo and Treatment Planning Systems. Med Phys 2006. [DOI: 10.1118/1.2244634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Darko J, Joshi C, Osei E, Halsall T, Dai J, Salomons G, Kerr A. SU-FF-T-198: Dosimetry of Small Lung Lesions with EGSnrc Monte Carlo and Treatment Planning Systems. Med Phys 2006. [DOI: 10.1118/1.2241121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Osei E, Bradley B, Fleck A, Darko J. SU-FF-T-343: Normalized Data for the Estimation of Fetal Radiation Dose From Radiotherapy of the Breast. Med Phys 2006. [DOI: 10.1118/1.2241264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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La Scala GC, O'Donovan DA, Yeung I, Darko J, Addison PD, Neligan PC, Pang CY, Forrest CR. Radiation-induced craniofacial bone growth inhibition: efficacy of cytoprotection following a fractionated dose regimen. Plast Reconstr Surg 2006; 115:1973-85. [PMID: 15923846 DOI: 10.1097/01.prs.0000163322.22436.3b] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Severe craniofacial growth disturbances are noted in 66 to 100 percent of children with head and neck cancers who received radiotherapy during their growing years. The authors have previously demonstrated the prevention of radiation-induced craniofacial bone growth inhibition following single-dose orthovoltage radiation to the orbitozygomatic complex in an infant rabbit model through the administration of the cytoprotective agent amifostine (WR-2721) before radiation treatment. The purpose of this study was to investigate the efficacy of cytoprotection using a fractionated dose regimen that better approximates the clinical application of radiation therapy. METHODS Thirty 7-week-old male New Zealand rabbits were randomized into three groups (n = 10), each receiving six fractions of orthovoltage radiation to the right orbitozygomatic complex: group C, sham irradiation control; group F35, total dose of 35 Gy; and group F35A, total dose of 35 Gy with administration of amifostine 200 mg/kg intravenously 20 minutes before each fraction. Bone growth was evaluated up to skeletal maturity (age 21 weeks) with serial radiographs and computed tomography scans for cephalometric analysis, bone volume, and bone density measurements. RESULTS Fractionated radiation resulted in significant (p < 0.05) bone growth inhibition compared with sham radiation in 16 of 21 cephalometric parameters measured and significantly (p < 0.05) reduced bone volume of the rabbit orbitozygomatic complex. Pretreatment with amifostine before each radiation fraction prevented growth deformities in four cephalometric parameters and significantly (p < 0.05) attenuated these effects in another seven parameters compared with radiated animals. Bone volumes were also significantly (p < 0.05) improved in F35A animals compared with F35 animals. CONCLUSIONS This study establishes that fractionation of orthovoltage radiation does not prevent the development of growth disturbances of the rabbit craniofacial skeleton and also demonstrates that preirradiation administration of amifostine is highly effective in the prevention and attenuation of radiation-induced craniofacial bone growth inhibition.
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Affiliation(s)
- Giorgio C La Scala
- Division of Plastic Surgery, The Hospital for Sick Children Center for Craniofacial Care and Research, Ontario, Canada
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Joshi C, Darko J, Vidyasagar P, Schreiner J. Po-Poster - 11: Interface dosimetry around air cavities for cobalt-60, 6MV and 15MV beams using EGSnrc/DOSXYZnrc Monte-Carlo simulation. Med Phys 2005. [DOI: 10.1118/1.2030990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Osei EK, Darko J, Mosseri A, Jezioranski J. EGSNRCMonte Carlo study of the effect of photon energy and field margin in phantoms simulating small lung lesions. Med Phys 2003; 30:2706-14. [PMID: 14596309 DOI: 10.1118/1.1607551] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The dose distribution in small lung tumors (coin lesions) is affected by the combined effects of reduced attenuation of photons and extended range of electrons in lung. The increased range of electrons in low-density tissues can lead to loss of field flatness and increased penumbra width, especially at high energies. The EGSNRC Monte Carlo code, together with DOSXYZNRC, a three-dimensional voxel dose calculation module has been used to study the characteristics of the penumbra in the region of the target-lung interfaces for various radiation beam energies, lung densities, target-field edge distances, target size, and depth. The Monte Carlo model was validated by film measurements made in acrylic (simulating a tumor) imbedded in cork (simulating the lung). Beam profiles that are deemed to be acceptable are defined as those in which no point within the planning target volume (target volume plus 1 cm margin) received less than 95% of the dose prescribed to the center of the target. For parallel opposed beams and 2 cm cube target size, 6 MV photons produce superior dose distribution with respect to penumbra at the lateral, anterior, and posterior surfaces and midplane of the simulated target, with a target-field edge distance of 2.5 cm. A lesser target-field edge distance of 2.0 cm is required for 4 MV photons to produce acceptable dose distribution. To achieve equivalent dose distribution with 10 and 18 MV photons, a target-field edge distance of 3.0 and 3.5 cm, respectaively, is required. For a simulated target size of 4 cm cube, a target-field edge distance of 2, 2.5, and 3 cm is required for 6, 10, and 18 MV photons, respectively, to yield acceptable PTV coverage. The effect, which is predominant in determining the target dose, depends on the beam energy, target-field edge distance, lung density, and the depth and size of the target.
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Affiliation(s)
- E K Osei
- Princess Margaret Hospital, Department of Radiation Physics, 610 University Avenue, Toronto, Ontario M5G 2M9, Canada.
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Yeung I, Darko J, Haider M, Milosevic M, Fyles A. 1029 Quantification of microvasculature in cervix carcinoma with functional CT imaging. EJC Suppl 2003. [DOI: 10.1016/s1359-6349(03)91055-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Koh TS, Zeman V, Darko J, Lee TY, Milosevic MF, Haider M, Warde P, Yeung IW. The inclusion of capillary distribution in the adiabatic tissue homogeneity model of blood flow. Phys Med Biol 2001; 46:1519-38. [PMID: 11384068 DOI: 10.1088/0031-9155/46/5/313] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We have developed a non-invasive imaging tracer kinetic model for blood flow which takes into account the distribution of capillaries in tissue. Each individual capillary is assumed to follow the adiabatic tissue homogeneity model. The main strength of our new model is in its ability to quantify the functional distribution of capillaries by the standard deviation in the time taken by blood to pass through the tissue. We have applied our model to the human prostate and have tested two different types of distribution functions. Both distribution functions yielded very similar predictions for the various model parameters, and in particular for the standard deviation in transit time. Our motivation for developing this model is the fact that the capillary distribution in cancerous tissue is drastically different from in normal tissue. We believe that there is great potential for our model to be used as a prognostic tool in cancer treatment. For example, an accurate knowledge of the distribution in transit times might result in an accurate estimate of the degree of tumour hypoxia, which is crucial to the success of radiation therapy.
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Affiliation(s)
- T S Koh
- Department of Radiation Physics, Princess Margaret Hospital, Toronto, ON, Canada
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