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Roussakis Y, Anagnostopoulos G. Physical and Dosimetric Aspects of the Iridium-Knife. Front Oncol 2021; 11:728452. [PMID: 34858815 PMCID: PMC8630660 DOI: 10.3389/fonc.2021.728452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Accepted: 10/19/2021] [Indexed: 11/13/2022] Open
Abstract
The three-dimensional iridium-192 (192Ir) high-dose-rate (HDR) brachytherapy manifests itself as a high-precision, hypofractionated, dose-escalating, minimally invasive method in the armamentarium of contemporary radiation oncology clinical applications. In this study, the physical aspects of the 192Ir radionuclide are presented. Its dosimetric application in HDR brachytherapy for different anatomical sites (prostate, gynecological malignancies, liver, and intrathoracic tumors) as well as the corresponding dosimetric comparison with the stereotactic body radiation therapy (SBRT) techniques based on a representative selection of dosimetric publications is reviewed and illustrated.
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Affiliation(s)
- Yiannis Roussakis
- Department of Medical Physics, German Oncology Center, Limassol, Cyprus
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Lee J, Ramadan S, Kim A, Alayed Y, Ravi A. Dosimetric impact of tracheostomy devices in head and neck cancer patients. J Appl Clin Med Phys 2020; 21:26-32. [PMID: 32374922 PMCID: PMC7324706 DOI: 10.1002/acm2.12862] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2019] [Revised: 02/26/2020] [Accepted: 02/29/2020] [Indexed: 12/31/2022] Open
Abstract
INTRODUCTION The tracheostomy site and adjacent skin is at risk for recurrence in head/neck squamous cell cancer patients. The tracheostomy tube is an in situ device located directly over the tracheostomy site and may have clinical implications on the radiation dose delivered to the peristomal region. This study aimed to investigate this effect by comparing the prescribed treatment planning dose with the actual dose in vivo to the peristomal clinical target region. A retrospective, dosimetric study was performed with approval of the institutional research ethics board. METHODS Fifteen patients who had received high-dose radiotherapy to the tracheostomy region with in vivo dose measurements were included. The radiation dose at the skin surface underneath the tracheostomy device was measured using an optically stimulated luminescent dosimeter (OSLD) and was compared with the prescribed dose from the radiation planning system. The effect of the tracheostomy flange and/or soft tissue equivalent bolus on the peristomal dose was calculated. RESULTS AND DISCUSSION Patients with tracheostomy equipment in situ were found to have a 3.7% difference between their prescribed and actual dose. With a tissue equivalent bolus there was a 2.0% difference between predicted and actual. The mean prescribed single fraction dose (mean = 191.8 cGy, SD = 40.18) and OSLD measured dose (mean = 194.02 cGy, SD = 44.3) were found to have no significant difference. However, with the flange excluded from the planning simulation (density = air) target skin dose deviated from predicted by an average of 55.3% (range = 12.4-72.9, SD = 22.5) and volume coverage was not achieved. CONCLUSION In summary, the tracheostomy flange acts like bolus with a twofold increase in the skin surface dose. Changes in the peristomal apparatus from simulation to treatment needs to be considered to ensure that the simulated dose and coverage is achieved.
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Affiliation(s)
- Justin Lee
- Department of Radiation Oncology, Odette Cancer Centre, Sunnybrook Health Sciences Centre, Toronto, ON, Canada.,Department of Radiation Oncology, Juravinski Cancer Centre, Hamilton, ON, Canada.,Department of Radiation Oncology, University of Toronto, Toronto, ON, Canada
| | - Sherif Ramadan
- Department of Health Sciences, McMaster University, Hamilton, ON, Canada
| | - Anthony Kim
- Department of Radiation Oncology, Odette Cancer Centre, Sunnybrook Health Sciences Centre, Toronto, ON, Canada.,Department of Radiation Oncology, University of Toronto, Toronto, ON, Canada
| | - Yasir Alayed
- Department of Radiation Oncology, Odette Cancer Centre, Sunnybrook Health Sciences Centre, Toronto, ON, Canada.,Department of Radiation Oncology, University of Toronto, Toronto, ON, Canada
| | - Ananth Ravi
- Department of Radiation Oncology, University of Toronto, Toronto, ON, Canada.,Department of Medical Physics, Odette Cancer Centre, Sunnybrook Health Sciences Center, Toronto, ON, Canada
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Iridium-Knife: Another knife in radiation oncology. Brachytherapy 2017; 16:884-892. [PMID: 28392144 DOI: 10.1016/j.brachy.2017.03.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2016] [Revised: 02/19/2017] [Accepted: 03/07/2017] [Indexed: 01/30/2023]
Abstract
PURPOSE Intratarget dose escalation with superior conformity is a defining feature of three-dimensional (3D) iridium-192 (192Ir) high-dose-rate (HDR) brachytherapy (BRT). In this study, we analyzed the dosimetric characteristics of interstitial 192Ir HDR BRT for intrathoracic and cerebral malignancies. We examined the dose gradient sharpness of HDR BRT compared with that of linear accelerator-based stereotactic radiosurgery and stereotactic body radiation therapy, usually called X-Knife, to demonstrate that it may as well be called a Knife. METHODS AND MATERIALS Treatment plans for 10 patients with recurrent glioblastoma multiforme or intrathoracic malignancies, five of each entity, treated with X-Knife (stereotactic radiosurgery for glioblastoma multiforme and stereotactic body radiation therapy for intrathoracic malignancies) were replanned for simulated HDR BRT. For 3D BRT planning, we used identical structure sets and dose prescription as for the X-Knife planning. The indices for qualitative treatment plan analysis encompassed planning target volume coverage, conformity, dose falloff gradient, and the maximum dose-volume limits to different organs at risk. RESULTS Volume coverage in HDR plans was comparable to that calculated for X-Knife plans with no statistically significant difference in terms of conformity. The dose falloff gradient-sharpness-of the HDR plans was considerably steeper compared with the X-Knife plans. CONCLUSIONS Both 3D 192Ir HDR BRT and X-Knife are effective means for intratarget dose escalation with HDR BRT achieving at least equal conformity and a steeper dose falloff at the target volume margin. In this sense, it can reasonably be argued that 3D 192Ir HDR BRT deserves also to be called a Knife, namely Iridium-Knife.
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Denton TR, Shields LBE, Howe JN, Spalding AC. Quantifying isocenter measurements to establish clinically meaningful thresholds. J Appl Clin Med Phys 2015; 16:5183. [PMID: 26103187 PMCID: PMC5690087 DOI: 10.1120/jacmp.v16i2.5183] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Revised: 11/23/2014] [Accepted: 11/23/2014] [Indexed: 11/23/2022] Open
Abstract
A dataset range of isocenter congruency verification tests have been examined from a statistical perspective for the purpose of establishing tolerance levels that are meaningful, based on the fundamental limitation of linear accelerator isocentricity and the demands of a high-precision stereotactic radiosurgery program. Using a laser-defined isocenter, a total of 149 individual isocenter congruency tests were examined with recorded values for ideal spatial corrections to the isocenter test tool. These spatial corrections were determined from radiation exposures recorded on an electronic portal imaging device (EPID) at various gantry, collimator, and treatment couch combinations. The limitations of establishing an ideal isocenter were quantified from each variable which contributed to uncertainty in isocenter definition. Individual contributors to uncertainty, specifically, daily positioning setup errors, gantry sag, multileaf collimator (MLC) offset, and couch walkout, were isolated from isocenter congruency measurements to determine a clinically meaningful isocenter measurement. Variations in positioning of the test tool constituted, on average, 0.38 mm magnitude of correction. Gantry sag and MLC offset contributed 0.4 and 0.16 mm, respectively. Couch walkout had an average degrading effect to isocenter of 0.72 mm. Considering the magnitude of uncertainty contributed by each uncertainty variable and the nature of their combination, an appropriate schedule action and immediate action level were determined for use in analyzing daily isocenter congruency test results in a stereotactic radiosurgery (SRS) program. The recommendations of this study for this linear accelerator include a schedule action level of 1.25 mm and an immediate action level of 1.50mm, requiring prompt correction response from clinical medical physicists before SRS or stereotactic body radiosurgery (SBRT) is administered. These absolute values were derived from considering relative data from a specific linear accelerator and, therefore, represent a means by which a numerical quantity can be used as a test threshold with relative specificity to a particular linear accelerator.
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Affiliation(s)
- Travis R Denton
- The Norton Cancer Institute Radiation Center, Louisville, KY and Associates in Medical Physics, LLC, Greenbelt, MD.
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Ganesh KM, Pichandi A, Nehru RM, Ravikumar M. Design and Testing of Indigenous Cost Effective Three Dimensional Radiation Field Analyser (3D RFA). Technol Cancer Res Treat 2014; 13:195-209. [DOI: 10.7785/tcrt.2012.500370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The aim of the study is to design and validate an indigenous three dimensional Radiation Field Analyser (3D RFA). The feed system made for X, Y and Z axis movements is of lead screw with deep ball bearing mechanism made up of stain less steel driven by stepper motors with accuracy less than 0.5 mm. The telescopic column lifting unit was designed using linear actuation technology for lifting the water phantom. The acrylic phantom with dimensions of 800 × 750 × 570 mm was made with thickness of 15 mm. The software was developed in visual basic programming language, classified into two types, viz. beam analyzer software and beam acquisition software. The premeasurement checks were performed as per TG 106 recommendations. The physical parameters of photon PDDs such as Dmax, D10, D20and Quality Index (QI), and the electron PDDs such as R50, Rp, E0, Epoand X-ray contamination values can be obtained instantaneously by using the developed RFA system. Also the results for profile data such as field size, central axis deviation, penumbra, flatness and symmetry calculated according to various protocols can be obtained for both photon and electron beams. The result of PDDs for photon beams were compared with BJR25 supplement values and the profile data were compared with TG 40 recommendation. The results were in agreement with standard protocols.
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Affiliation(s)
- K. M. Ganesh
- Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Hosur Road, Bangalore 560029, India
| | - A. Pichandi
- Health Care Global Hospitals, Sampingeram Nagar, Bangalore 560027, India
| | - R. M. Nehru
- Atomic Energy Regulatory Board, Mumbai 400094, India
| | - M. Ravikumar
- Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Hosur Road, Bangalore 560029, India
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Siochi RA. Leakage reduction for the Siemens Moduleaf. J Appl Clin Med Phys 2009; 10:139-149. [PMID: 19458591 PMCID: PMC5720452 DOI: 10.1120/jacmp.v10i2.2894] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2008] [Revised: 12/01/2008] [Accepted: 12/02/2008] [Indexed: 11/25/2022] Open
Abstract
The ModuLeaf, an add‐on miniature multileaf collimator (MMLC) for the Siemens ONCOR linear accelerator, provides high resolution field shaping with a maximum interleaf leakage dose of 1.50% at 6 MV. However, beyond the maximum treatment field size, the distribution of leakage and scatter along the y‐axis is different from that of the x‐axis, with maximum leakage values of 1.53% and 0.39%, respectively. Such differences cannot be modeled in the Pinnacle treatment planning system. Also, within the 10 cm×12 cm treatment region, leakage from the crack between closed leaf ends was 3.76%. To resolve these issues, gaps in the ModuLeaf frame were filled with lead sheets, and the Siemens MLC was operated in MLC mode (rather than bank mode). As a result, a rectangle of 10.4 cm×11 cm was formed with the MLC leaves closed behind the Y jaws, whose opening was 10.4 cm. This significantly reduced the difference between the leakage patterns in the x and y directions, with maximum leakage doses of 0.43% outside the treatment region and 1.67% near the crack between abutting ModuLeaf leaves. The modification also reduced the mean square error between Pinnacle profiles and measured profiles in the tail region. PACS number: 87.56.jk
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Affiliation(s)
- R Alfredo Siochi
- Department of Radiation Oncology, University of Iowa Hospitals and Clinics, Iowa City, Iowa, U.S.A
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García-Garduño OA, Celis MÁ, Lárraga-Gutiérrez JM, Moreno-Jiménez S, Martínez-Dávalos A, Rodríguez-Villafuerte M. Radiation transmission, leakage and beam penumbra measurements of a micro-multileaf collimator using GafChromic EBT film. J Appl Clin Med Phys 2008; 9:90-98. [PMID: 18716595 PMCID: PMC5722293 DOI: 10.1120/jacmp.v9i3.2802] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2007] [Revised: 01/31/2008] [Accepted: 02/11/2008] [Indexed: 12/21/2022] Open
Abstract
Micro‐multileaf collimator systems coupled to linear accelerators for radioneurosurgery treatments require a rigorous dosimetric characterization in order to be used in 3D conformal and intensity modulated stereotactic radiosurgery and radiotherapy applications. This characterization involves high precision measurements of leaf transmission, leakage and beam penumbra through the collimation system and requires the use of detectors with high spatial resolution, high sensitivity and practically no energy dependence. In this work the use of GafChromic EBT radiochromic film to measure the basic dosimetric properties of the m3‐mMLC (BrainLAB, Germany) micro‐multileaf collimator system integrated to a 6 MV linear accelerator, is reported. Results show that average values of transmission and leakage radiation are 0.93±0.05% and 1.08±0.08%, respectively. The 80–20% beam penumbra were found to be 2.26±0.11 mm along the leaf side (perpendicular to leaf motion) and 2.31±0.11 mm along the leaf end (parallel to leaf motion) using square field sizes ranging from 9.1 to 1.8 cm. These measurements are in agreement with values reported in the literature for the same type of mMLC using different radiation detectors. PACS number: 87.56.N‐
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Affiliation(s)
- Olivia Amanda García-Garduño
- Laboratorio de Física Médica y Unidad de Radioneurocirugía, Instituto Nacional de Neurología y Neurocirugía, México D. F., México
| | - Miguel Ángel Celis
- Laboratorio de Física Médica y Unidad de Radioneurocirugía, Instituto Nacional de Neurología y Neurocirugía, México D. F., México
| | - José Manuel Lárraga-Gutiérrez
- Laboratorio de Física Médica y Unidad de Radioneurocirugía, Instituto Nacional de Neurología y Neurocirugía, México D. F., México
| | - Sergio Moreno-Jiménez
- Laboratorio de Física Médica y Unidad de Radioneurocirugía, Instituto Nacional de Neurología y Neurocirugía, México D. F., México
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