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Quiñones LÁ, Sánchez A, Pérez J, Seguro Á, Castro I, Castanedo M, Vicent D, Iborra MA. Thermoplastic polymers as water substitutes. Biomed Phys Eng Express 2024; 10:045009. [PMID: 38670074 DOI: 10.1088/2057-1976/ad43ee] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Accepted: 04/26/2024] [Indexed: 04/28/2024]
Abstract
Background. New applications of 3D printing have recently appeared in the fields of radiotherapy and radiology, but the knowledge of many radiological characteristics of the compounds involved is still limited. Therefore, studies are needed to improve our understanding about the transport and interaction of ionizing radiation in these materials.Purpose. The purpose of this study is to perform an analysis of the most important radiation interaction parameters in thermoplastic materials used in Fused Deposition Modeling 3D printing. Additionally, we propose improvements to bring their characteristics closer to those of water and use them as water substitutes in applications such as radiodiagnosis, external radiotherapy, and brachytherapy.Methods. We have calculated different magnitudes as mass linear attenuation, mass energy absorption coefficients, as well as stopping power and electronic density of several thermoplastic materials along with various compounds that have been used as water substitutes and in a new proposed blend. To perform these computations, we have used the XCOM and ESTAR databases from NIST and the EGSnrc code for Montecarlo simulations.Results. From the representation of the calculated interaction parameters, we have been able to establish relationships between their properties and the proportion of certain chemical elements. In addition, studying these same characteristics in different commercial solutions used as substitutes for water phantoms allows us to extrapolate improvements for these polymers.Conclusion. The radiological characteristics of the analyzed thermoplastic materials can be improved by adding some chemical elements with atomic numbers higher than oxygen and by using polyethylene in new blends.
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Affiliation(s)
- Luis Ángel Quiñones
- Medical Physics Service, Hospital Universitario Puerta del Mar, Avda. Ana de Viya, No 21. 11009, Cádiz, Spain
| | - Andrea Sánchez
- Medical Physics Service, Hospital Universitario Puerta del Mar, Avda. Ana de Viya, No 21. 11009, Cádiz, Spain
| | - Joaquín Pérez
- Medical Physics Service, Hospital Universitario Puerta del Mar, Avda. Ana de Viya, No 21. 11009, Cádiz, Spain
| | - Álvaro Seguro
- Medical Physics Service, Hospital Universitario Puerta del Mar, Avda. Ana de Viya, No 21. 11009, Cádiz, Spain
| | - Ignacio Castro
- Medical Physics Service, Hospital Universitario Puerta del Mar, Avda. Ana de Viya, No 21. 11009, Cádiz, Spain
| | - Miguel Castanedo
- Medical Physics Service, Hospital Universitario Puerta del Mar, Avda. Ana de Viya, No 21. 11009, Cádiz, Spain
| | - Diana Vicent
- Medical Physics Service, Hospital Universitario Puerta del Mar, Avda. Ana de Viya, No 21. 11009, Cádiz, Spain
| | - María Amparo Iborra
- Medical Physics Service, Hospital Universitario Puerta del Mar, Avda. Ana de Viya, No 21. 11009, Cádiz, Spain
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Aspradakis MM, Buchillier T, Kohler G, Kottler C, Krayenbühl J. SSRMP Recommendations No 9: Reference dosimetry in low and medium energy x-ray beams. Z Med Phys 2023; 33:601-617. [PMID: 37202239 PMCID: PMC10751714 DOI: 10.1016/j.zemedi.2022.12.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 12/18/2022] [Accepted: 12/19/2022] [Indexed: 05/20/2023]
Abstract
The SSRMP recommendations on reference dosimetry in kilovolt beams as used in radiation therapy were revised to establish current practice in Switzerland. The recommendations specify the dosimetry formalism, reference class dosimeter systems and conditions used for the calibration of low and medium energy x-ray beams. Practical guidance is provided on the determination of the beam quality specifier and all corrections required for converting instrument readings to absorbed dose to water. Guidance is also provided on the determination of relative dose under non-reference conditions and on the cross calibration of instruments. The effect of lack of electron equilibrium and influence of contaminant electrons when using thin window plane parallel chambers at x-ray tube potentials higher than 50kV is elaborated in an appendix. In Switzerland the calibration of the reference system used for dosimetry is regulated by law. METAS and IRA are the authorities providing this calibration service to the radiotherapy departments. The last appendix of these recommendations summarise this calibration chain.
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Affiliation(s)
| | - Thierry Buchillier
- Institut de radiophysique (IRA), Rue du Grand-Pré 1, 1007 Lausanne, Switzerland
| | - Götz Kohler
- Klinik für Strahlentherapie und Radioonkologie, Universitätsspital Basel, Petersgraben 4, 4031 Basel, Switzerland
| | - Christian Kottler
- Eidgenössisches Institut für Metrologie (METAS), Lindenweg 50, 3003 Bern-Wabern, Switzerland
| | - Jérôme Krayenbühl
- Klinik für Radio-Onkologie, Universitätsspital Zürich, Rämistrasse 100, 8091 Zurich, Switzerland
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Lozares-Cordero S, Bermejo-Barbanoj C, Badías-Herbera A, Ibáñez-Carreras R, Ligorred-Padilla L, Ponce-Ortega JM, González-Pérez V, Gandía-Martínez A, Font-Gómez JA, Blas-Borroy O, González-Ibáñez D. An open-source development based on photogrammetry for a real-time IORT treatment planning system. Phys Med 2023; 112:102622. [PMID: 37331081 DOI: 10.1016/j.ejmp.2023.102622] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2023] [Revised: 06/02/2023] [Accepted: 06/06/2023] [Indexed: 06/20/2023] Open
Abstract
PURPOSE This study presents a treatment planning system for intraoperative low-energy photon radiotherapy based on photogrammetry from real images of the surgical site taken in the operating room. MATERIAL AND METHODS The study population comprised 15 patients with soft-tissue sarcoma. The system obtains the images of the area to be irradiated with a smartphone or tablet, so that the absorbed doses in the tissue can be calculated from the reconstruction without the need for computed tomography. The system was commissioned using 3D printing of the reconstructions of the tumor beds. The absorbed doses at various points were verified using radiochromic films that were suitably calibrated for the corresponding energy and beam quality. RESULTS The average reconstruction time of the 3D model from the video sequence in the 15 patients was 229,6±7,0 s. The entire procedure, including video capture, reconstruction, planning, and dose calculation was 520,6±39,9 s. Absorbed doses were measured on the 3D printed model with radiochromic film, the differences between these measurements and those calculated by the treatment planning system were 1.4% at the applicator surface, 2.6% at 1 cm, 3.9% at 2 cm and 6.2% at 3 cm. CONCLUSIONS The study shows a photogrammetry-based low-energy photon IORT planning system, capable of obtaining real-time images inside the operating room, immediately after removal of the tumor and immediately before irradiation. The system was commissioned with radiochromic films measurements in 3D-printed model.
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Affiliation(s)
- Sergio Lozares-Cordero
- Physics and Radiation Protection Department, Miguel Servet University Hospital, Zaragoza, Spain.
| | | | - Alberto Badías-Herbera
- Higher Technical School of Industrial Engineering, Polytechnic University of Madrid, Spain
| | | | - Luis Ligorred-Padilla
- Esophagogastric Surgery and Sarcoma Unit (Department of General and Gastrointestinal Surgery), Miguel Servet University Hospital, Zaragoza, Spain
| | | | | | | | - José Antonio Font-Gómez
- Physics and Radiation Protection Department, Miguel Servet University Hospital, Zaragoza, Spain
| | - Olga Blas-Borroy
- Engineering and Maintenance Service, Miguel Servet University Hospital, Zaragoza, Spain
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Xiong Z, Zhong Y, Banks TI, Reynolds R, Chiu T, Tan J, Zhang Y, Parsons D, Yan Y, Godley A, Stojadinovic S. Machine characterization and central axis depth dose data of a superficial x-ray radiotherapy unit. Biomed Phys Eng Express 2022; 9. [PMID: 36541531 DOI: 10.1088/2057-1976/aca611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Accepted: 11/23/2022] [Indexed: 11/27/2022]
Abstract
Objectives. The purpose of this study is to present data from the clinical commissioning of an Xstrahl 150 x-ray unit used for superficial radiotherapy,Methods. Commissioning tasks included vendor acceptance tests, timer reproducibility, linearity and end-effect measurements, half-value layer (HVL) measurements, inverse square law verification, head-leakage measurements, and beam output calibration. In addition, percent depth dose (PDD) curves were determined for different combinations of filter/kV settings and applicators. Automated PDD water phantom scans were performed utilizing four contemporary detectors: a microDiamond detector, a microSilicon detector, an EDGE detector, and a PinPoint ionization chamber. The measured PDD data were compared to the published values in BJR Supplement 25,Results. The x-ray unit's mechanical, safety, and radiation characteristics were within vendor-stated specifications. Across sixty commissioned x-ray beams, the PDDs determined in water using solid state detectors were in excellent agreement with the BJR 25 data. For the lower (<100 kVp) and medium-energy (≥100 kVp) superficial beams the average agreement was within [-3.6,+0.4]% and [-3.7,+1.4]% range, respectively. For the high-energy superficial (low-energy orthovoltage) x-rays at 150 kVp, the average difference for the largest 20 × 20 cm2collimator was (-0.7 ± 1.0)%,Conclusions. This study presents machine characterization data collected for clinical use of a superficial x-ray unit. Special focus was placed on utilizing contemporary detectors and techniques for the relative PDD measurements using a motorized water phantom. The results in this study confirm that the aggregate values published in the BJR 25 report still serve as a valid benchmark when comparing data from site-specific measurements, or the reference data for clinical utilization without such measurements,Advances in knowledge. This paper presents comprehensive data from the acceptance and commissioning of a modern kilovoltage superficial x-ray radiotherapy machine. Comparisons between the PDD data measured in this study using different detectors and BJR 25 data are highlighted.
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Affiliation(s)
- Zhenyu Xiong
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, United States of America.,Department of Radiation Oncology, Rutgers Cancer Institute of New Jersey, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ, United States of America
| | - Yuncheng Zhong
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
| | - Thomas I Banks
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
| | - Robert Reynolds
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
| | - Tsuicheng Chiu
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
| | - Jun Tan
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
| | - You Zhang
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
| | - David Parsons
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
| | - Yulong Yan
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
| | - Andrew Godley
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
| | - Strahinja Stojadinovic
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
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Determination of the radiological properties of materials: A new approximation method for calculation of the mass attenuation coefficients. Appl Radiat Isot 2022; 187:110340. [DOI: 10.1016/j.apradiso.2022.110340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 05/09/2022] [Accepted: 06/17/2022] [Indexed: 11/18/2022]
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Gilling L, Ali O. Organ dose from Varian XI and Varian OBI systems are clinically comparable for pelvic CBCT imaging. Phys Eng Sci Med 2022; 45:279-285. [PMID: 35143026 DOI: 10.1007/s13246-021-01090-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 12/07/2021] [Indexed: 11/27/2022]
Abstract
Pelvic cone-beam computed tomography (CBCT) occurs daily in many radiotherapy clinics as a part of image-guided verification before treatment. These images are acquired by the use of ionizing radiation. The dose received by CBCT imaging is often not quantified in a patient's radiation therapy prescription. The purpose of this work was to quantify the dose from a TrueBeam XI pelvic CBCT imaging system. The dose to organs from this imaging protocol was then compared with published dose data for OBI v1.4 pelvic CBCT imaging. A model of the Varian XI imager was constructed using GATE Monte Carlo scripting language. The model was calibrated by correlation with experimental measurements. An IBA 3D water tank was used to perform relative dose measurements in water. An adult anthropomorphic Alderson phantom with embedded thermolumeniscent dosimeters was used to evaluate dose from prostate CBCT imaging. Following the calibration, the GATE model was used to simulate the dose from the XI pelvic CBCT protocol to the ICRP computational anthropomorphic phantom. The Monte Carlo model constructed in GATE was validated for use in dose estimates for the XI pelvic imaging protocol. The D50 and D10 values tabulated the pelvic CBCT protocol show that doses to organs in the pelvic region are comparable for both systems. For a clinician who intends to evaluate the dose to organs as a result of CBCT imaging of the pelvis from the TrueBeam XI system, for the purposes of treatment planning, the doses reported for OBI v1.4 given in AAPM TG-180 provide a valid estimate.
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Affiliation(s)
- Luke Gilling
- Medical Physics Department, Waikato District Health Board, Hamilton, New Zealand.
| | - Omer Ali
- Medical Physics Department, Waikato District Health Board, Hamilton, New Zealand
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Araki F, Umeno S. SURFACE DOSE ESTIMATION BY A KAP METER FOR KILOVOLTAGE X-RAY BEAMS. RADIATION PROTECTION DOSIMETRY 2021; 195:124-131. [PMID: 34423373 DOI: 10.1093/rpd/ncab122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 06/12/2021] [Accepted: 07/19/2021] [Indexed: 06/13/2023]
Abstract
This study aims to estimate the entrance surface dose (ESD) of a water phantom for kilovoltage x-ray beams using an air kerma area product meter (KAP meter) equipped in an x-ray unit. The KAP meter was calibrated in terms of the ESD determined by a plane-parallel ionization chamber based on a 60Co absorbed dose-to-water calibration coefficient, ${N}_{D,w}^{{}^{60}\mathrm{C}\mathrm{o}}$. The ESD measured using the KAP meter was verified by comparing it with that estimated by the air kerma calibration coefficient, NK, for x-ray beam qualities. The ratio of ESDs based on ${N}_{D,w}^{{}^{60}\mathrm{C}\mathrm{o}}$ and NK was 1.003 on average and independent of the beam quality. The ESD by the KAP meter was an agreement within ±1.5% with that measured using the plane-parallel chamber for 10 × 10-30 × 30 cm2 fields with a source-surface distance of 75-150 cm. It was possible to estimate the ESD directly in a water phantom for x-ray beams without correction factors compared to the existing air kerma calibration, using a KAP meter calibrated based on ${N}_{D,w}^{{}^{60}\mathrm{C}\mathrm{o}}$.
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Affiliation(s)
- F Araki
- Department of Health Sciences, Faculty of Life Sciences, Kumamoto University, 4-24-1 Kuhonji, Chuo-ku, Kumamoto 862-0976, Japan
| | - S Umeno
- SAGA Heavy Ion Medical Accelerator in Tosu, 3049 Harakogamachi, Tosu, Saga, 841-0071, Japan
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8
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Prabhu S, Bharadwaj DY, Podder R, Bubbly SG, Gudennavar SB. Natural polymer-based hydrogels as prospective tissue equivalent materials for radiation therapy and dosimetry. Phys Eng Sci Med 2021; 44:1107-1120. [PMID: 34398391 DOI: 10.1007/s13246-021-01047-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Accepted: 08/10/2021] [Indexed: 01/14/2023]
Abstract
Natural polymer-based hydrogels have been extensively employed in tissue engineering and biomedical applications, owing to their biodegradability and biocompatibility. In the present work, we have investigated the efficacy of hydrogels such as agarose, hyaluronan, gelatin, carrageenan, chitosan, sodium alginate and collagen as tissue equivalent materials with respect to photon and charged particle (electron, proton and alpha particle) interactions, for use in radiation therapy and dosimetry. Tissue equivalence has been investigated by computing photon mass energy absorption coefficient (μen/ρ), kinetic energy released per unit mass (KERMA), equivalent atomic number (Zeq) and energy absorption build-up factors (EABF) relative to human tissues (soft tissue, cortical bone, skeletal muscle, breast tissue, lung tissue, adipose tissue, skin tissue, brain) in the energy range of 0.015-15 MeV. Ratio of effective atomic numbers (Zeff) have been examined for tissue-equivalence in the energy range of 10 keV-1 GeV for charged particle interactions. Analysis using standard theoretical formulations revealed that all the selected natural polymers can serve as good tissue equivalent materials with respect to all human tissues except cortical bone. Notably, sodium alginate, collagen and hyaluronan are found to have radiation interaction characteristics close to that of human tissues. These results would be useful in deciding on the suitability of a natural polymer hydrogel as tissue substitute in the desired energy range.
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Affiliation(s)
- Srilakshmi Prabhu
- Department of Physics and Electronics, CHRIST (Deemed to be University), Bangalore Central Campus, Bengaluru, Karnataka, 560029, India
| | - Dhanya Y Bharadwaj
- Department of Physics and Electronics, CHRIST (Deemed to be University), Bangalore Central Campus, Bengaluru, Karnataka, 560029, India
| | - Rachaita Podder
- Department of Physics and Electronics, CHRIST (Deemed to be University), Bangalore Central Campus, Bengaluru, Karnataka, 560029, India
| | - S G Bubbly
- Department of Physics and Electronics, CHRIST (Deemed to be University), Bangalore Central Campus, Bengaluru, Karnataka, 560029, India.
| | - S B Gudennavar
- Department of Physics and Electronics, CHRIST (Deemed to be University), Bangalore Central Campus, Bengaluru, Karnataka, 560029, India
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Pang T, Yang B, Liu X, Castle JR, Yu L, Liu N, Li W, Dong T, Qiu J, Chen Q. Investigation of absolute dose calibration accuracy for TomoTherapy using real water. J Appl Clin Med Phys 2021; 22:139-145. [PMID: 34060222 PMCID: PMC8200510 DOI: 10.1002/acm2.13311] [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: 12/31/2020] [Revised: 03/23/2021] [Accepted: 05/10/2021] [Indexed: 12/03/2022] Open
Abstract
A systematic bias in TomoTherapy output calibration was reported by the Imaging and Radiation Oncology Core Houston (IROC‐H) after analyzing intensity‐modulated radiation therapy (IMRT) credentialing results from hundreds of TomoTherapy units. Multiple theories were developed to explain this observation. One theory was that the use of a solid water “cheese” phantom instead of real water in the calibration measurement was the culprit. A phantom filled with distilled water was built to investigate whether our TomoTherapy was miscalibrated due to the use of a solid water phantom. A miscalibration of −1.47% was detected on our TomoTherapy unit. It is found that despite following the vendor's updated recommendation on computed tomography (CT) number to density calibration, the cheese phantom was still mapped to a density of 1.028 g/cm3, rather than the 1.01 g/cm3 value reported in literature. When the density of the cheese phantom was modified to 1.01 g/cm3 in the treatment planning system, the measurement also indicated that our TomoTherapy machine was miscalibrated by −1.52%, agreeing with the real water phantom findings. Our single‐institution finding showed that the cheese phantom density assignment can introduce greater than 1% errors in the TomoTherapy absolute dose calibration. It is recommended that the absolute dose calibration for TomoTherapy be performed either in real water or in the cheese phantom with the density in TPS overridden as 1.01 g/cm3.
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Affiliation(s)
- Tingtian Pang
- Department of Radiation Oncology, Peking Union Medical College Hospital, Beijing, China
| | - Bo Yang
- Department of Radiation Oncology, Peking Union Medical College Hospital, Beijing, China
| | - Xia Liu
- Department of Radiation Oncology, Peking Union Medical College Hospital, Beijing, China
| | - James R Castle
- Department of Radiation Medicine, University of Kentucky, Lexington, Kentucky, USA
| | - Lang Yu
- Department of Radiation Oncology, Peking Union Medical College Hospital, Beijing, China
| | - Nan Liu
- Department of Radiation Oncology, Peking Union Medical College Hospital, Beijing, China
| | - Wenbo Li
- Department of Radiation Oncology, Peking Union Medical College Hospital, Beijing, China
| | - Tingting Dong
- Department of Radiation Oncology, Peking Union Medical College Hospital, Beijing, China
| | - Jie Qiu
- Department of Radiation Oncology, Peking Union Medical College Hospital, Beijing, China
| | - Quan Chen
- Department of Radiation Medicine, University of Kentucky, Lexington, Kentucky, USA
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Kairn T, Maxwell SK, Trapp JV, Crowe SB. ASSESSMENT OF INTEGRITY AND LEAD-EQUIVALENCE OF SHIELDED GARMENTS USING TWO-DIMENSIONAL X-RAY IMAGES FROM A COMPUTED TOMOGRAPHY SCANNER. RADIATION PROTECTION DOSIMETRY 2021; 193:155-164. [PMID: 33822208 DOI: 10.1093/rpd/ncab037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 02/13/2021] [Accepted: 02/22/2021] [Indexed: 06/12/2023]
Abstract
Shielded garments are widely recommended for occupational radiation protection in diagnostic and interventional radiology. This study investigated a novel method for efficiently verifying shielded garment integrity while simultaneously acquiring data for lead-equivalence measurements, using two-dimensional topogram images from computed tomography (CT) scanners. This method was tested against more-conventional measurements with superficial and orthovoltage radiotherapy treatment beams, for 12 shielded garments containing 3 different lead-free shielding materials. Despite some energy-dependent results, all shielded garments approximately achieved their specified lead-equivalence for the energy range expected during clinical use for fluoroscopy procedures, except for three shielded skirts that required two layers of material to be overlapped at the front. All lead-equivalence measurements from CT topograms agreed with or conservatively underestimated the kV narrow-beam results. This method is potentially useful for independently assessing the shielding properties of new shielded garments and performing annual checks for damage or degradation of existing shielded garments.
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Affiliation(s)
- T Kairn
- Cancer Care Services, Royal Brisbane and Women's Hospital, Butterfield St, Herston 4029, Qld, Australia
- School of Chemistry and Physics, Queensland University of Technology, 2 George St, Brisbane 4000, Qld, Australia
- Herston Biofabrication Institute, Metro North Hospital and Health Service, Butterfield St, Herston 4029, Qld, Australia
- School of Information Technology and Electrical Engineering, University of Queensland, St Lucia, Qld 4072, Australia
| | - S K Maxwell
- Cancer Care Services, Royal Brisbane and Women's Hospital, Butterfield St, Herston 4029, Qld, Australia
| | - J V Trapp
- School of Chemistry and Physics, Queensland University of Technology, 2 George St, Brisbane 4000, Qld, Australia
| | - S B Crowe
- Cancer Care Services, Royal Brisbane and Women's Hospital, Butterfield St, Herston 4029, Qld, Australia
- School of Chemistry and Physics, Queensland University of Technology, 2 George St, Brisbane 4000, Qld, Australia
- Herston Biofabrication Institute, Metro North Hospital and Health Service, Butterfield St, Herston 4029, Qld, Australia
- School of Information Technology and Electrical Engineering, University of Queensland, St Lucia, Qld 4072, Australia
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Araki F. Monte Carlo determination of a nanoDot OSLD response using quality index for diagnostic kilovoltage X-ray beams. Phys Med 2021; 84:101-108. [PMID: 33887616 DOI: 10.1016/j.ejmp.2021.03.031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 03/22/2021] [Accepted: 03/29/2021] [Indexed: 11/17/2022] Open
Abstract
PURPOSE This study aims to investigate the energy response of an optically stimulated luminescent dosimeter known as nanoDot for diagnostic kilovoltage X-ray beams via Monte Carlo calculations. METHODS The nanoDot response is calculated as a function of X-ray beam quality in free air and on a water phantom surface using Monte Carlo simulations. The X-ray fluence spectra are classified using the quality index (QI), which is defined as the ratio of the effective energy to the maximum energy of the photons. The response is calculated for X-ray fluence spectra with QIs of 0.4, 0.5, and 0.6 with tube voltages of 50-137.6 kVp and monoenergetic photon beams. The surface dose estimated using the calculated response is verified by comparing it with that measured using an ionization chamber. RESULTS The nanoDot response in free air for monoenergetic photon beams (QI = 1.0) varies significantly at photon energies below 100 keV and reaches a factor of 3.6 at 25-30 keV. The response differs by up to approximately 6% between QIs of 0.4 and 0.6 for the same half-value layer (HVL). The response at the phantom surface decreases slightly owing to the backscatter effect, and it is almost independent of the field size. The agreement between the surface dose estimated using the nanoDot and that measured using the ionization chamber for assessing X-ray beam qualities is less than 2%. CONCLUSIONS The nanoDot response is indicated as a function of HVL for the specified QIs, and it enables the direct surface dose measurement.
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Affiliation(s)
- Fujio Araki
- Department of Health Sciences, Faculty of Life Sciences, Kumamoto University, 4-24-1 Kuhonji, Chuo-ku, Kumamoto 862-0976, Japan.
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12
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Charles PH, Crowe S, Kairn T. Recommendations for simulating and measuring with biofabricated lung equivalent materials based on atomic composition analysis. Phys Eng Sci Med 2021; 44:331-335. [PMID: 33591538 DOI: 10.1007/s13246-021-00979-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 01/28/2021] [Indexed: 11/25/2022]
Abstract
Monte Carlo simulations of lung equivalent materials often involve the density being artificially lowered rather than a true lung tissue (or equivalent plastic) and air composition being simulated. This study used atomic composition analysis to test the suitability of this method. Atomic composition analysis was also used to test the suitability of 3D printing PLA or ABS with air to simulate lung tissue. It was found that there was minimal atomic composition difference when using an artificially lowered density, with a 0.8 % difference in Nitrogen the largest observed. Therefore, excluding infill pattern effects, lowering the density of the lung tissue (or plastic) in simulations should be sufficiently accurate to simulate an inhaled lung, without the need to explicitly include the air component. The average electron density of 3D printed PLA and air, and ABS and air were just 0.3 % and 1.3 % different to inhaled lung, confirming their adequacy for MV photon dosimetry. However large average atomic number differences (5.6 % and 20.4 % respectively) mean that they are unlikely to be suitable for kV photon dosimetry.
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Affiliation(s)
- Paul H Charles
- Herston Biofabrication Institute, Brisbane, QLD, Australia. .,School of Information Technology and Electrical Engineering, University of Queensland, Brisbane, QLD, Australia. .,Science and Engineering Faculty, Queensland University of Technology, Brisbane, QLD, Australia.
| | - Scott Crowe
- Herston Biofabrication Institute, Brisbane, QLD, Australia.,School of Information Technology and Electrical Engineering, University of Queensland, Brisbane, QLD, Australia.,Science and Engineering Faculty, Queensland University of Technology, Brisbane, QLD, Australia.,Cancer Care Services, Royal Brisbane & Women's Hospital, Brisbane, QLD, Australia
| | - Tanya Kairn
- Herston Biofabrication Institute, Brisbane, QLD, Australia.,School of Information Technology and Electrical Engineering, University of Queensland, Brisbane, QLD, Australia.,Science and Engineering Faculty, Queensland University of Technology, Brisbane, QLD, Australia.,Cancer Care Services, Royal Brisbane & Women's Hospital, Brisbane, QLD, Australia
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Lozares S, Font JA, Gandía A, Campos A, Flamarique S, Ibáñez R, Villa D, Alba V, Jiménez S, Hernández M, Casamayor C, Vicente I, Hernando E, Rubio P. In vivo dosimetry in low-voltage IORT breast treatments with XR-RV3 radiochromic film. Phys Med 2021; 81:173-181. [PMID: 33465753 DOI: 10.1016/j.ejmp.2020.12.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 12/12/2020] [Accepted: 12/16/2020] [Indexed: 12/30/2022] Open
Abstract
PURPOSE The objectives of the study were to establish a procedure for in vivo film-based dosimetry for intraoperative radiotherapy (IORT), evaluate the typical doses delivered to organs at risk, and verify the dose prescription. MATERIALS AND METHODS In vivo dose measurements were studied using XR-RV3 radiochromic films in 30 patients with breast cancer undergoing IORT using the Axxent® device (Xoft Inc.). The stability of the radiochromic films in the energy ranges used was verified by taking measurements at different depths. The stability of the scanner response was tested, and 5 different calibration curves were constructed for different beam qualities. Six pieces of film were placed in each of the 30 patients. All the pieces were correctly sterilized and checked to ensure that the process did not affect the outcome. All calibration and dose measurements were analyzed using the Radiochromic.com software application. RESULTS The doses were measured for 30 patients. The doses in contact with the applicator (prescription zone) were 19.8 ± 0.9 Gy. In the skin areas, the doses were as follows: 1-2 cm from the applicator, 1.86 ± 0.77 Gy; 2-5 cm, 0.73 ± 0.14 Gy; and greater than 5 cm, 0.28 ± 0.17 Gy. The dose delivered to the pectoral muscle (tungsten shielding disc) was 0.51 ± 0.27 Gy. CONCLUSIONS The study demonstrated the viability of XR-RV3 films for in vivo dose measurement in the dose and energy ranges applied in a complex procedure, such as breast IORT. The doses in organs at risk were far below the tolerances for cases such as those studied.
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Affiliation(s)
- Sergio Lozares
- Medical Physics Department. Miguel Servet University Hospital Zaragoza, Spain.
| | - Jose A Font
- Medical Physics Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Almudena Gandía
- Medical Physics Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Arantxa Campos
- Radiation Oncology Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Sonia Flamarique
- Radiation Oncology Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Reyes Ibáñez
- Radiation Oncology Department. Miguel Servet University Hospital Zaragoza, Spain
| | - David Villa
- Medical Physics Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Verónica Alba
- Medical Physics Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Sara Jiménez
- Medical Physics Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Mónica Hernández
- Medical Physics Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Carmen Casamayor
- Endocrine, Bariatric and Breast Surgery Unit. General and Digestive Surgery Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Isabel Vicente
- Breast Unit. Gynaecology Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Ernesto Hernando
- Endocrine, Bariatric and Breast Surgery Unit. General and Digestive Surgery Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Patricia Rubio
- Breast Unit. Gynaecology Department. Miguel Servet University Hospital Zaragoza, Spain
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Baines J, Powers M, Shoobridge A, Van Der Walt M, Sim L. An alternative to the use of lead for patient treatment shielding in superficial radiotherapy. Phys Eng Sci Med 2021; 44:93-102. [PMID: 33398635 DOI: 10.1007/s13246-020-00956-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 12/02/2020] [Indexed: 11/29/2022]
Abstract
Lead shielding is commonly used in the delivery of superficial radiotherapy albeit that the toxicity of this substance is of concern. The feasibility of using a non-toxic alternative, AttenuFlex™, is assessed using Xstrahl and Sensus treatment units. A series of lead and AttenuFlex™ circular cut outs and applicators were used with superficial beams (1.0-8.5 mm Al HVL) to measure percentage depth dose (PDD), output factors (OF) and surface dose correction factors (DCF). X-ray transmission for each material was determined for each beam quality. For these measurements an Advanced Markus chamber either embedded within a virtual water phantom (PDD, OF, transmission) or placed on the surface of the phantom with entrance window downstream (DCF), was used. The depth of the phantom is 10 cm for PDD and surface OF measurements. DCF(t) measurements were obtained with underlying lead or AttenuFlex™ at depth t = 0.1-10 cm. Additionally, using EBT3 film fluorescent surface doses, to non-target tissue, due to underlying lead or AttenuFlex™ were compared. PDDs and OFs for both materials were within ± 1%. Lead and AttenuFlex™ transmission differences were clinically acceptable, all transmission values were < 5% and non-target doses were comparable. The variation of DCF(t) for lead and AttenuFlex™ exhibit a minima for all beams. In the minima region energy and applicator dependent differences between DCF(lead) and DCF(AttenuFlex™) are observed. These differences do not preclude the use of AttenuFlex™ as an alternative to lead in superficial therapy.
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Affiliation(s)
- John Baines
- Cancer Centre, Townsville University Hospital, 100 Angus Smith Drive, Douglas, QLD, 4814, Australia.
| | - Marcus Powers
- Cancer Centre, Townsville University Hospital, 100 Angus Smith Drive, Douglas, QLD, 4814, Australia
| | - Ariadne Shoobridge
- Cancer Centre, Townsville University Hospital, 100 Angus Smith Drive, Douglas, QLD, 4814, Australia
| | - Marchant Van Der Walt
- Cancer Centre, Townsville University Hospital, 100 Angus Smith Drive, Douglas, QLD, 4814, Australia
| | - Lucy Sim
- Radiation Oncology Princess Alexandra Hospital Raymond Terrace, 31 Raymond Terrace, South Brisbane, QLD, 4101, Australia
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Predicting the required thickness of custom shielding materials in kilovoltage radiotherapy beams. Phys Med 2021; 81:94-101. [DOI: 10.1016/j.ejmp.2020.12.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 12/07/2020] [Accepted: 12/08/2020] [Indexed: 12/15/2022] Open
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Fulkerson RK, Perez‐Calatayud J, Ballester F, Buzurovic I, Kim Y, Niatsetski Y, Ouhib Z, Pai S, Rivard MJ, Rong Y, Siebert F, Thomadsen BR, Weigand F. Surface brachytherapy: Joint report of the AAPM and the GEC‐ESTRO Task Group No. 253. Med Phys 2020; 47:e951-e987. [DOI: 10.1002/mp.14436] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2019] [Revised: 07/15/2020] [Accepted: 07/16/2020] [Indexed: 02/06/2023] Open
Affiliation(s)
- Regina K. Fulkerson
- Department of Medical Physics University of Wisconsin–Madison Madison WI53705 USA
| | - Jose Perez‐Calatayud
- Radiotherapy Department La Fe Hospital Valencia46026 Spain
- Radiotherapy Department Clinica Benidorm Alicante03501 Spain
| | - Facundo Ballester
- Department of Atomic, Molecular and Nuclear Physics University of Valencia Burjassot46100 Spain
| | - Ivan Buzurovic
- Dana‐Farber/Brigham and Women’s Cancer Center Harvard Medical School Boston MA02115 USA
| | - Yongbok Kim
- Department of Radiation Oncology University of Arizona Tucson AZ85724 USA
| | - Yury Niatsetski
- R&D Elekta Brachytherapy Waardgelder 1 Veenendaal3903 DD Netherlands
| | - Zoubir Ouhib
- Radiation Oncology Department Lynn Regional Cancer CenterBoca Raton Community Hospital Boca Raton FL33486 USA
| | - Sujatha Pai
- Radion Inc. 20380 Town Center Lane, Suite 135 Cupertino CA95014 USA
| | - Mark J. Rivard
- Department of Radiation Oncology Alpert Medical School Brown University Providence RI02903 USA
| | - Yi Rong
- Department of Radiation Oncology University of California Davis Comprehensive Cancer Center Sacramento CA95817 USA
| | - Frank‐André Siebert
- UK S‐HCampus Kiel, Klinik fur Strahlentherapie (Radioonkologie) Arnold‐Heller‐Str. 3Haus 50 KielD‐24105 Germany
| | - Bruce R. Thomadsen
- Department of Medical Physics University of Wisconsin–Madison Madison WI53705 USA
| | - Frank Weigand
- Carl Zeiss Meditec AG Rudolf‐Eber‐Straße 11 Oberkochen73447 Germany
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Prabhu S, Bubbly SG, Gudennavar SB. Synthetic polymer hydrogels as potential tissue phantoms in radiation therapy and dosimetry. Biomed Phys Eng Express 2020; 6:055008. [PMID: 33444239 DOI: 10.1088/2057-1976/aba209] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The efficacy of synthetic polymers as hydrogel phantoms for radiation therapy and dosimetry has been investigated for photon and charged particle (electron, proton and alpha particle) interactions. Tissue equivalence has been studied in terms of photon mass energy-absorption coefficients, KERMA (kinetic energy released per unit mass), equivalent atomic number and energy absorption build-up factors, relative to human tissues (skin, soft tissue, cortical bone and skeletal muscle), in the energy range 0.015-15 MeV. For charged particle interactions, ratio of effective atomic number is examined for tissue-equivalence in the energy region of 10 keV-1 GeV. Well established theoretical formulations are used for computation of photon mass-energy absorption effective atomic number, electron density and KERMA. Five-parameter geometric progression (G-P) fitting approximation is used to compute the values of energy absorption build-up factors. Effective atomic number for charged particle interaction is determined using logarithmic interpolation method. Using the analytical methodology, it has been revealed that all the selected synthetic polymers have good tissue-equivalence relative to all tissue except cortical bone. In particular, polyglycolic acid (PGA) and poly-lactic-co-glycolic acid (PLGA) prove to be best substitute material for photon interactions. On the other hand, % difference between effective atomic number for charged particle relative to human tissues is found least for polyethylene glycol (PEG) demonstrating adequate tissue-equivalence. Therefore, the present study is expected to be useful to choose most appropriate phantom material for radiation therapy.
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Affiliation(s)
- Srilakshmi Prabhu
- Department of Physics and Electronics, CHRIST (Deemed to be University), Bangalore Central Campus, Bengaluru - 560029, Karnataka, India
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Water equivalence of a solid phantom material for radiation dosimetry applications. PHYSICS & IMAGING IN RADIATION ONCOLOGY 2020; 14:43-47. [PMID: 33458313 PMCID: PMC7807691 DOI: 10.1016/j.phro.2020.05.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Revised: 05/14/2020] [Accepted: 05/15/2020] [Indexed: 11/24/2022]
Abstract
Radiological water equivalence of solid phantoms used for radiotherapy is often desired, but is non-trivial to achieve across the range of therapeutic energies. This study evaluated the water equivalence of a new solid phantom material in beam qualities relevant to radiotherapy applications. In-phantom measured depth distributions were compared to that in water to assess the relative attenuation and scatter characteristics of the material. The phantom material was found to be dosimetrically equivalent to water within (1.0 ± 1.0)% for megavoltage photon beam qualities, (1.5 ± 1.3)% for megavoltage electron beam qualities, (1.5 ± 1.5)% for medium-energy kilovoltage X-rays and (3.0 ± 1.5)% for low-energy kilovoltage X-rays.
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Frimaio A, Nascimento BC, Barrio RM, Campos LL, Costa PR. Reprint of “X-ray spectrometry applied for determination of linear attenuation coefficient of tissue-equivalent materials”. Radiat Phys Chem Oxf Engl 1993 2020. [DOI: 10.1016/j.radphyschem.2019.108553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Tuğrul T, Eroğul O. Analysis of water-equivalent materials used during irradiation in the clinic with XCOM and BEAMnrc. JOURNAL OF RADIATION RESEARCH AND APPLIED SCIENCES 2020. [DOI: 10.1080/16878507.2019.1708576] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Taylan Tuğrul
- Department of Radiation Oncology, Medicine Faculty of Van Yüzüncü Yıl University, Van, TURKEY
| | - Osman Eroğul
- Department of Biomedical Engineering, TOBB University of Economics and Technology, Ankara, TURKEY
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Frimaio A, Nascimento BC, Barrio RM, Campos LL, Costa PR. X-ray spectrometry applied for determination of linear attenuation coefficient of tissue-equivalent materials. Radiat Phys Chem Oxf Engl 1993 2019. [DOI: 10.1016/j.radphyschem.2019.03.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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23
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Hill R, Healy B, Butler D, Odgers D, Gill S, Lye J, Gorjiara T, Pope D, Hill B. Australasian recommendations for quality assurance in kilovoltage radiation therapy from the Kilovoltage Dosimetry Working Group of the Australasian College of Physical Scientists and Engineers in Medicine. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2018; 41:781-808. [DOI: 10.1007/s13246-018-0692-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Hewson EA, Butson MJ, Hill R. Evaluating TOPAS for the calculation of backscatter factors for low energy x-ray beams. ACTA ACUST UNITED AC 2018; 63:195014. [DOI: 10.1088/1361-6560/aadf28] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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25
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Martin E, Sowards K, Wang B. Investigation of a source model for a new electronic brachytherapy tandem by film measurement. J Appl Clin Med Phys 2018; 19:640-650. [PMID: 30105891 PMCID: PMC6123150 DOI: 10.1002/acm2.12440] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 06/01/2018] [Accepted: 07/16/2018] [Indexed: 12/26/2022] Open
Abstract
PURPOSE To investigate the accuracy of a vendor-supplied source model for a new Xoft Axxent 0-degree titanium tandem by film measurement. METHODS We measured the anisotropy factors at varying distances and angles from the tandem in water using radiochromic film (Gafchromic EBT3) and an Epson Perfection v750 desktop flatbed scanner (US Epson, Long Beach, CA). A 0-degree tandem was placed vertically in a water phantom. Four pieces of film, each at varying depths, were positioned orthogonal to the longitudinal axis of the tandem for azimuthal anisotropy measurements. Polar anisotropy measurements were taken with the film aligned parallel to the tandem. An absolute dose calibration for the film was verified with a PTW 34013 Soft X-Ray Chamber. The film measurements were analyzed using different color channels. The measured polar anisotropy for varying source positions was compared to the vendor's data. Azimuthal anisotropy was measured as a function of the radius and angle, and normalized to the mean value over all angles at the specified radius. RESULTS The azimuthal anisotropy of the tandem and source was found to be consistent for different positions along the tandem's longitudinal axis and at varying distances from the tandem. Absolute dose using a calibrated parallel plate chamber showed agreement to within 2% of expected TPS values. The custom tandem, which has a thicker tip than the wall, was attenuating the 50 kV photons more than expected, at the angles where the photons had more wall material to traverse. This discrepancy was verified at different distances from the tandem and with different measurement techniques. As distance increased, anisotropy values had better agreement. CONCLUSIONS We quantified the agreement between the measured and provided anisotropy factors for a new Xoft Axxent 0-degree titanium tandem. Radiochromic film response at low kV energy was also investigated. Our results showed that vendor-supplied TG-43 values were appropriate for clinical use at majority of the angles. A rigorous quality assurance method for new electronic brachytherapy sources and applicators, along with complete knowledge of all dosimetric measuring tools, should be implemented for all parts of the verification and commissioning process.
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Affiliation(s)
- Elijah Martin
- Department of Radiation OncologyUniversity of LouisvilleLouisvilleKYUSA
| | - Keith Sowards
- Department of Radiation OncologyUniversity of LouisvilleLouisvilleKYUSA
| | - Brian Wang
- Department of Radiation OncologyUniversity of LouisvilleLouisvilleKYUSA
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26
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Crowe SB, Pross Z, Nilsson S, Dawes J, Kairn T, Lancaster CM. Characterisation of radiological properties of a brachytherapy moulding material. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2018; 41:731-737. [PMID: 30128906 DOI: 10.1007/s13246-018-0673-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Accepted: 08/09/2018] [Indexed: 11/24/2022]
Abstract
The use of a non-water-equivalent personalised mould for gynaecological brachytherapy treatments can result in a substantial dose reduction at the treatment site, compared to calculated dose, in lieu of a dose calculation algorithm capable of modelling non-water-equivalent materials. This study describes the characterisation of the radiological properties of a brachytherapy applicator moulding material. Simple line source correction factors for an 192Ir source are obtained through Monte Carlo simulations and verified by film measurements. The dwell position corrections are used to estimate aggregate correction factors for dose deliveries that involve multiple dwell positions, in terms of treatment length, applicator radii and depth of reference dose. For the Fricotan moulding material used locally, the dose reductions varied from 1% for an applicator radius of 0.5 cm to > 4% for radii exceeding 2 cm. The method described in this paper could be used to develop correction factors for other non-water-equivalent moulding materials, in a TG-43UI dose calculation environment.
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Affiliation(s)
- Scott B Crowe
- Cancer Care Services, Royal Brisbane & Women's Hospital, Brisbane, Australia. .,Queensland University of Technology, Brisbane, Australia.
| | - Zac Pross
- Queensland University of Technology, Brisbane, Australia
| | - Sanna Nilsson
- Cancer Care Services, Royal Brisbane & Women's Hospital, Brisbane, Australia.,Nelune Comprehensive Cancer Centre, Prince of Wales Hospital, Randwick, Australia
| | - Jodi Dawes
- Cancer Care Services, Royal Brisbane & Women's Hospital, Brisbane, Australia
| | - Tanya Kairn
- Cancer Care Services, Royal Brisbane & Women's Hospital, Brisbane, Australia.,Queensland University of Technology, Brisbane, Australia
| | - Craig M Lancaster
- Cancer Care Services, Royal Brisbane & Women's Hospital, Brisbane, Australia
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Safigholi H, Song WY. Calculation of water equivalent ratios for various materials at proton energies ranging 10–500 MeV using MCNP, FLUKA, and GEANT4 Monte Carlo codes. Phys Med Biol 2018; 63:155010. [DOI: 10.1088/1361-6560/aad0bd] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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28
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Acuña-Gómez OL, Garnica-Garza HM. Improvement of kilovoltage beam output with a transmission x-ray target: radiological optimization and cooling system design. Biomed Phys Eng Express 2018. [DOI: 10.1088/2057-1976/aa99eb] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Dosimetric characterisation of anthropomorphic PRESAGE® dosimeter and EBT2 film for partial breast radiotherapy. JOURNAL OF RADIOTHERAPY IN PRACTICE 2017. [DOI: 10.1017/s1460396917000450] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractPurposeWhole-breast external beam radiotherapy results in significant reduction in the risk for breast cancer-related death, but this may be offset by an increase in deaths from other causes and toxicity to surrounding organs. Partial breast irradiation techniques are approaches that treat only the lumpectomy area rather than the whole breast. Quality assurance in the radiation therapy treatment planning process is essential to ensure accurate dose delivery to the patient. For this purpose, this article compares the results from an anthropomorphic PRESAGE® dosimeter, radiation treatment planning system and from the GAFCHROMIC® EBT2 film.Materials and methodsA breast dosimeter was created and a three-field partial plan was generated in the Pinnacle3 treatment planning system. Dose distribution comparisons were made between Pinnacle3 treatment planning system, GAFCHROMIC® EBT2 film and PRESAGE® dosimeter. Dose–volume histograms (DVHs), gamma maps and line profiles were used to evaluate the comparison.ResultsDVHs of gross tumour volume, clinical tumour volume and planning tumour volume for the PRESAGE® dosimeter and Pinnacle3 treatment planning system shows that both measured and calculated statistics were in agreement, with a value of 97.8% of the prescribed dose. Gamma map comparisons showed that all three distributions passed 95% at the ±3%/±3 mm criteria. Comparisons of isodose line distribution between the PRESAGE® dosimeter, EBT2 film and planning system demonstrated agreement, with an average difference of 1.5%.ConclusionsThis work demonstrated the feasibility of PRESAGE® to function as an anthropomorphic phantom and laid the foundation for research studies in PRESAGE®/optical-computed tomography three-dimensional dosimetry with the most complex anthropomorphic phantoms.
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Schoenfeld AA, Thieben M, Harder D, Poppe B, Chofor N. Evaluation of water-mimicking solid phantom materials for use in HDR and LDR brachytherapy dosimetry. Phys Med Biol 2017; 62:N561-N572. [PMID: 29072195 DOI: 10.1088/1361-6560/aa9636] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
In modern HDR or LDR brachytherapy with photon emitters, fast checks of the dose profiles generated in water or a water-equivalent phantom have to be available in the interest of patient safety. However, the commercially available brachytherapy photon sources cover a wide range of photon emission spectra, and the range of the in-phantom photon spectrum is further widened by Compton scattering, so that the achievement of water-mimicking properties of such phantoms involves high requirements on their atomic composition. In order to classify the degree of water equivalence of the numerous commercially available solid water-mimicking phantom materials and the energy ranges of their applicability, the radial profiles of the absorbed dose to water, D w, have been calculated using Monte Carlo simulations in these materials and in water phantoms of the same dimensions. This study includes the HDR therapy sources Nucletron Flexisource Co-60 HDR (60Co), Eckert und Ziegler BEBIG GmbH CSM-11 (137Cs), Implant Sciences Corporation HDR Yb-169 Source 4140 (169Yb) as well as the LDR therapy sources IsoRay Inc. Proxcelan CS-1 (131Cs), IsoAid Advantage I-125 IAI-125A (125I), and IsoAid Advantage Pd-103 IAPd-103A (103Pd). Thereby our previous comparison between phantom materials and water surrounding a Varian GammaMed Plus HDR therapy 192Ir source (Schoenfeld et al 2015) has been complemented. Simulations were performed in cylindrical phantoms consisting of either water or the materials RW1, RW3, Solid Water, HE Solid Water, Virtual Water, Plastic Water DT, Plastic Water LR, Original Plastic Water (2015), Plastic Water (1995), Blue Water, polyethylene, polystyrene and PMMA. While for 192Ir, 137Cs and 60Co most phantom materials can be regarded as water equivalent, for 169Yb the materials Plastic Water LR, Plastic Water DT and RW1 appear as water equivalent. For the low-energy sources 106Pd, 131Cs and 125I, only Plastic Water LR can be classified as water equivalent.
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Affiliation(s)
- Andreas A Schoenfeld
- Clinic of Radiotherapy and Radiation Oncology-University Clinic of Medical Radiation Physics, Pius-Hospital, Carl von Ossietzky University, Oldenburg, Germany
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Liang LH, Tomic N, Vuong T, Aldelaijan S, Bekerat H, DeBlois F, Seuntjens J, Devic S. Physics aspects of the Papillon technique-Five decades later. Brachytherapy 2017; 17:234-243. [PMID: 29102741 DOI: 10.1016/j.brachy.2017.09.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 09/26/2017] [Accepted: 09/26/2017] [Indexed: 12/15/2022]
Abstract
PURPOSE The Papillon technique using 50-kVp soft X-rays to treat rectal adenocarcinomas was developed and clinically implemented in the 1960s. We describe differences between accurate dosimetry and clinical implementation of this technique that is extending from its very inception to date. METHODS AND MATERIALS A renaissance of the Papillon technique occurred with two recently introduced 50-kVp systems: Papillon+ by Ariane and a custom-made rectal applicator (consisting of a surface applicator inserted into a proctoscope) by iCAD's Xoft Axxent Electronic Brachytherapy (eBT) System (iCad, Inc., Sunnyvale, CA). In contrast to the initial design, we investigated the impact of introducing a plastic lid, which would provide more reproducible and more accurate dose delivery across the rectal adenocarcinoma patient population. We use both parallel-plate chamber and radiochromic film dosimeters to determine differences in basic dosimetry characteristics (beam half-value layers, outputs, percent depth doses, and profiles) between the Xoft Electronic Brachytherapy rectal applicator system with and without the plastic lid in place. RESULTS Compared to the open-cone applicator, the proposed applicator with the plastic lid produces a slightly harder (more penetrating) beam quality (half-value layer of 1.4 vs. 1.3-mm Al), but with reduced output (by 33%), and a slightly broader beam with flatness not worse than 3% and symmetry not worse than 2%. CONCLUSIONS In addition to characterizing beam properties modified by the possible introduction of the plastic cap, we also pointed out and addressed misconceptions in the use of radiochromic films for dose measurements at low-energy photon beams.
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Affiliation(s)
- Li Heng Liang
- Radiation Oncology Department, Jewish General Hospital, Montreal, Quebec, Canada; Medical Physics Unit, McGill University, Montreal, Quebec, Canada
| | - Nada Tomic
- Radiation Oncology Department, Jewish General Hospital, Montreal, Quebec, Canada; Medical Physics Unit, McGill University, Montreal, Quebec, Canada
| | - Te Vuong
- Radiation Oncology Department, Jewish General Hospital, Montreal, Quebec, Canada; Oncology Department, McGill University, Montreal, Quebec, Canada
| | - Saad Aldelaijan
- Medical Physics Unit, McGill University, Montreal, Quebec, Canada; Biological & Biomedical Engineering Department, Montreal Neurological Institute, Montréal, Québec, Canada; Biomedical Physics Department, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Hamed Bekerat
- Radiation Oncology Department, Jewish General Hospital, Montreal, Quebec, Canada; Medical Physics Unit, McGill University, Montreal, Quebec, Canada
| | - Francois DeBlois
- Radiation Oncology Department, Jewish General Hospital, Montreal, Quebec, Canada; Medical Physics Unit, McGill University, Montreal, Quebec, Canada
| | - Jan Seuntjens
- Medical Physics Unit, McGill University, Montreal, Quebec, Canada; Oncology Department, McGill University, Montreal, Quebec, Canada
| | - Slobodan Devic
- Radiation Oncology Department, Jewish General Hospital, Montreal, Quebec, Canada; Medical Physics Unit, McGill University, Montreal, Quebec, Canada; Segal Cancer Centre, Jewish General Hospital, McGill University, Montréal, Québec, Canada.
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Kurudirek M. Effective atomic number of soft tissue, water and air for interaction of various hadrons, leptons and isotopes of hydrogen. Int J Radiat Biol 2017; 93:1299-1305. [PMID: 28978247 DOI: 10.1080/09553002.2018.1388546] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
PURPOSE Characterization of soft tissue, water and air in terms of effective atomic number (Zeff) with respect to the interactions of hadrons, leptons and isotopes of hydrogen. METHOD Mass collision stopping powers (MCSPs) were calculated first using Bethe formula. Then, these values were used to estimate Zeff using linear-logarithmic interpolation. A scale equation was also used to calculate MCSP. RESULTS Variation in Zeff, over the 0.5-50 MeV energy range considered, is minimum for muon and pion (π meson) interactions (relative difference [RD] ≤ 7%), while maximum variation has been noticed in Zefffor heavy charged particles, i.e. alpha particle (RD ≤ 26%). The highest values of Zeff were obtained for muon particle, the lightest particle while the minimum values of Zeff were obtained for alpha particle interaction. Except for very low kinetic energies, water equivalence of soft tissue is very satisfactory (RD ≤ 3%). The Zeff of water relative to air was found to be almost constant at high energies. The present results should be valid for especially high energies where the Bethe formula can be applied. This applies to relatively higher energies (>2 MeV) for heavier particles such as alpha particles and applies to relatively lower energies (>0.5 MeV) for lighter particles such as protons. CONCLUSIONS In view of the importance of water equivalence in particle therapy, new data on Zeff in soft tissue, water and air for fundamental particle interaction should be important. Results revealed that soft tissue could be considered as water equivalent for interaction of various fundamental particles.
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Affiliation(s)
- Murat Kurudirek
- a Department of Physics, Faculty of Science , Ataturk University , Erzurum , Turkey
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Marashdeh M, Tajuddin A, Bauk S, Hashim R. Dosimetric evaluation of Rhizophora spp. binderless particleboard phantom for diagnostic X-ray energy. Radiat Phys Chem Oxf Engl 1993 2017. [DOI: 10.1016/j.radphyschem.2017.03.030] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Hosseini Daghigh SM, Baghani HR, Aghamiri SMR, Mahdavi SR. Evaluating the performance of TG-43 protocol in esophageal HDR brachytherapy viewpoint to trachea inhomogeneity. Rep Pract Oncol Radiother 2017; 22:284-289. [DOI: 10.1016/j.rpor.2017.04.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2016] [Revised: 02/24/2017] [Accepted: 04/18/2017] [Indexed: 11/30/2022] Open
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Cameron M, Cornelius I, Cutajar D, Davis J, Rosenfeld A, Lerch M, Guatelli S. Comparison of phantom materials for use in quality assurance of microbeam radiation therapy. JOURNAL OF SYNCHROTRON RADIATION 2017; 24:866-876. [PMID: 28664894 DOI: 10.1107/s1600577517005641] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2016] [Accepted: 04/13/2017] [Indexed: 06/07/2023]
Abstract
Microbeam radiation therapy (MRT) is a promising radiotherapy modality that uses arrays of spatially fractionated micrometre-sized beams of synchrotron radiation to irradiate tumours. Routine dosimetry quality assurance (QA) prior to treatment is necessary to identify any changes in beam condition from the treatment plan, and is undertaken using solid homogeneous phantoms. Solid phantoms are designed for, and routinely used in, megavoltage X-ray beam radiation therapy. These solid phantoms are not necessarily designed to be water-equivalent at low X-ray energies, and therefore may not be suitable for MRT QA. This work quantitatively determines the most appropriate solid phantom to use in dosimetric MRT QA. Simulated dose profiles of various phantom materials were compared with those calculated in water under the same conditions. The phantoms under consideration were RMI457 Solid Water (Gammex-RMI, Middleton, WI, USA), Plastic Water (CIRS, Norfolk, VA, USA), Plastic Water DT (CIRS, Norfolk, VA, USA), PAGAT (CIRS, Norfolk, VA, USA), RW3 Solid Phantom (PTW Freiburg, Freiburg, Germany), PMMA, Virtual Water (Med-Cal, Verona, WI, USA) and Perspex. RMI457 Solid Water and Virtual Water were found to be the best approximations for water in MRT dosimetry (within ±3% deviation in peak and 6% in valley). RW3 and Plastic Water DT approximate the relative dose distribution in water (within ±3% deviation in the peak and 5% in the valley). PAGAT, PMMA, Perspex and Plastic Water are not recommended to be used as phantoms for MRT QA, due to dosimetric discrepancies greater than 5%.
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Affiliation(s)
- Matthew Cameron
- CMRP, University of Wollongong, Wollongong, NSW 2522, Australia
| | | | - Dean Cutajar
- CMRP, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Jeremy Davis
- CMRP, University of Wollongong, Wollongong, NSW 2522, Australia
| | | | - Michael Lerch
- CMRP, University of Wollongong, Wollongong, NSW 2522, Australia
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Kron T, Ungureanu E, Antony R, Hardcastle N, Clements N, Ukath J, Fox C, Lonski P, Wanigaratne D, Haworth A. Patient specific quality control for Stereotactic Ablative Body Radiotherapy (SABR): it takes more than one phantom. ACTA ACUST UNITED AC 2017. [DOI: 10.1088/1742-6596/777/1/012017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Stansook N, Petasecca M, Utitsarn K, Newall M, Metcalfe P, Carolan M, Lerch M, Rosenfeld AB. The angular dependence of a two dimensional monolithic detector array for dosimetry in small radiation fields. ACTA ACUST UNITED AC 2017. [DOI: 10.1088/1742-6596/777/1/012020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Commissioning and quality assurance procedures for the HDR Valencia skin applicators. J Contemp Brachytherapy 2016; 8:441-447. [PMID: 27895687 PMCID: PMC5116455 DOI: 10.5114/jcb.2016.63387] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 09/17/2016] [Indexed: 11/17/2022] Open
Abstract
The Valencia applicators (Nucletron, an Elekta company, Elekta AB, Stockholm, Sweden) are cup-shaped tungsten applicators with a flattening filter used to collimate the radiation produced by a high-dose-rate (HDR) 192Ir source, and provide a homogeneous absorbed dose at a given depth. This beam quality provides a good option for the treatment of skin lesions at shallow depth (3-4 mm). The user must perform commissioning and periodic testing of these applicators to guarantee the proper and safe delivery of the intended absorbed dose, as recommended in the standards in radiation oncology. In this study, based on AAPM and GEC-ESTRO guidelines for brachytherapy units and our experience, a set of tests for the commissioning and periodic testing of the Valencia applicators is proposed. These include general considerations, verification of the manufacturer documentation and physical integrity, evaluation of the source-to-indexer distance and reproducibility, setting the library plan in the treatment planning system, evaluation of flatness and symmetry, absolute output and percentage depth dose verification, independent calculation of the treatment time, and visual inspection of the applicator before each treatment. For each test, the proposed methodology, equipment, frequency, expected results, and tolerance levels (when applicable) are provided.
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Butler DJ, Lye JE, Wright TE, Crossley D, Sharpe PHG, Stevenson AW, Livingstone J, Crosbie JC. Absorbed dose determination in kilovoltage X-ray synchrotron radiation using alanine dosimeters. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2016; 39:943-950. [PMID: 27585452 DOI: 10.1007/s13246-016-0479-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 08/25/2016] [Indexed: 11/28/2022]
Abstract
Alanine dosimeters from the National Physical Laboratory (NPL) in the UK were irradiated using kilovoltage synchrotron radiation at the imaging and medical beam line (IMBL) at the Australian Synchrotron. A 20 × 20 mm2 area was irradiated by scanning the phantom containing the alanine through the 1 mm × 20 mm beam at a constant velocity. The polychromatic beam had an average energy of 95 keV and nominal absorbed dose to water rate of 250 Gy/s. The absorbed dose to water in the solid water phantom was first determined using a PTW Model 31014 PinPoint ionization chamber traceable to a graphite calorimeter. The alanine was read out at NPL using correction factors determined for 60Co, traceable to NPL standards, and a published energy correction was applied to correct for the effect of the synchrotron beam quality. The ratio of the doses determined by alanine at NPL and those determined at the synchrotron was 0.975 (standard uncertainty 0.042) when alanine energy correction factors published by Waldeland et al. (Waldeland E, Hole E O, Sagstuen E and Malinen E, Med. Phys. 2010, 37, 3569) were used, and 0.996 (standard uncertainty 0.031) when factors by Anton et al. (Anton M, Büermann L., Phys Med Biol. 2015 60 6113-29) were used. The results provide additional verification of the IMBL dosimetry.
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Affiliation(s)
- D J Butler
- Australian Radiation Protection and Nuclear Safety Agency (ARPANSA), Yallambie, Victoria, 3085, Australia.
| | - J E Lye
- Australian Radiation Protection and Nuclear Safety Agency (ARPANSA), Yallambie, Victoria, 3085, Australia
| | - T E Wright
- Australian Radiation Protection and Nuclear Safety Agency (ARPANSA), Yallambie, Victoria, 3085, Australia
| | - D Crossley
- National Physical Laboratory, Teddington, UK
| | | | - A W Stevenson
- Australian Synchrotron, 800 Blackburn Road, Clayton, VIC, 3168, Australia
| | - J Livingstone
- Australian Synchrotron, 800 Blackburn Road, Clayton, VIC, 3168, Australia
| | - J C Crosbie
- School of Science, RMIT University, 124 La Trobe Street, Melbourne, VIC, 3000, Australia.,William Buckland Radiotherapy Centre, Alfred Hospital, Commercial Road, Melbourne, VIC, 3004, Australia
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Kron T, Lehmann J, Greer PB. Dosimetry of ionising radiation in modern radiation oncology. Phys Med Biol 2016; 61:R167-205. [DOI: 10.1088/0031-9155/61/14/r167] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Aslam A, Kakakhel MB, Shahid SA, Younas L, Zareen S. Soft tissue and water substitutes for megavoltage photon beams: An EGSnrc-based evaluation. J Appl Clin Med Phys 2016; 17:408-415. [PMID: 26894338 PMCID: PMC5690209 DOI: 10.1120/jacmp.v17i1.5700] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Revised: 08/24/2015] [Accepted: 08/22/2015] [Indexed: 11/29/2022] Open
Abstract
In this work, soft‐tissue equivalence of water, polystyrene, PMMA and water equivalence of polystyrene, and PMMA has been assessed for multiple megavoltage photon beams and field sizes. EGSnrc based Monte Carlo (MC) codes, BEAMnrc and DOSXYZnrc are used for the linac head modeling and the phantom dose calculations, respectively. Percentage depth doses (PDDs) are scored for two field sizes (5×5 cm2, 10×10 cm2) and photon energies (6 MV and 10 MV) in water, polystyrene, PMMA, and soft tissue. The comparisons of PDDs show that soft‐tissue equivalence of various materials varies with the depth in the phantom, field size, and photon energy. Water and PMMA are found to be the closest soft‐tissue and water substitutes, respectively. Soft‐tissue and water equivalence of dosimetry materials need to be evaluated for a range of photon energies and field sizes before their application in complex radiation beams. PACS numbers: 87.55.Gh, 87.55.K‐
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Liebmann M, Poppe B, von Boetticher H. Computed tomography dosimetry with high-resolution detectors commonly used in radiotherapy - an energy dependence study. J Appl Clin Med Phys 2015; 16:396–407. [PMID: 26699294 PMCID: PMC5690150 DOI: 10.1120/jacmp.v16i5.5302] [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: 08/27/2014] [Revised: 05/19/2015] [Accepted: 05/04/2015] [Indexed: 11/23/2022] Open
Abstract
New methods of dosimetry in computed tomography (CT) X‐ray fields require the use of high‐resolution detectors instead of pencil‐type ionization chambers typically used for CT dose index (CTDI) measurements. This paper presents a study on the suitability of a wide range of ionization chambers, diodes, and a two‐dimensional detector array, used primarily in radiation therapy, for CT and cone‐beam CT dosimetry. Specifically, the energy dependence of these detectors from 50 kVp up to 125 kVp is reported. All measurements were performed in reference to a calibrated diode for use in this energy region. The radiation quality correction factors provided by the manufacturer were used, depending on the measured half‐value layer (HVL) for the particular X‐ray beam. Our study demonstrated the general usability of thimble ionization chambers. These thimble ionization chambers showed a maximum variation in energy response of 5%. Ionization chambers with even smaller sensitive volume, and which exhibit similar variation in energy dependence, can be used if higher spatial resolution is required. Furthermore, the investigated detectors are better suited for dosimetry at CT and CBCT units than conventional large volume or flat detectors, due to their rotational symmetry. Nevertheless, a flat detector can be used for certain measurement tasks, such as the acquisition of percent depth‐dose curves or beam profiles for nonrotating beams, which are important for beam characterization. PACS numbers: 87.57.uq, 87.56.Da, 87.57.Q‐
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Affiliation(s)
- Mario Liebmann
- Carl-von-Ossietzky University Oldenburg;Klinikum Links der Weser.
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Candela-Juan C, Vijande J, García-Martínez T, Niatsetski Y, Nauta G, Schuurman J, Ouhib Z, Ballester F, Perez-Calatayud J. Comparison and uncertainty evaluation of different calibration protocols and ionization chambers for low-energy surface brachytherapy dosimetry. Med Phys 2015; 42:4954-64. [PMID: 26233221 DOI: 10.1118/1.4927059] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
PURPOSE A surface electronic brachytherapy (EBT) device is in fact an x-ray source collimated with specific applicators. Low-energy (<100 kVp) x-ray beam dosimetry faces several challenges that need to be addressed. A number of calibration protocols have been published for x-ray beam dosimetry. The media in which measurements are performed are the fundamental difference between them. The aim of this study was to evaluate the surface dose rate of a low-energy x-ray source with small field applicators using different calibration standards and different small-volume ionization chambers, comparing the values and uncertainties of each methodology. METHODS The surface dose rate of the EBT unit Esteya (Elekta Brachytherapy, The Netherlands), a 69.5 kVp x-ray source with applicators of 10, 15, 20, 25, and 30 mm diameter, was evaluated using the AAPM TG-61 (based on air kerma) and International Atomic Energy Agency (IAEA) TRS-398 (based on absorbed dose to water) dosimetry protocols for low-energy photon beams. A plane parallel T34013 ionization chamber (PTW Freiburg, Germany) calibrated in terms of both absorbed dose to water and air kerma was used to compare the two dosimetry protocols. Another PTW chamber of the same model was used to evaluate the reproducibility between these chambers. Measurements were also performed with two different Exradin A20 (Standard Imaging, Inc., Middleton, WI) chambers calibrated in terms of air kerma. RESULTS Differences between surface dose rates measured in air and in water using the T34013 chamber range from 1.6% to 3.3%. No field size dependence has been observed. Differences are below 3.7% when measurements with the A20 and the T34013 chambers calibrated in air are compared. Estimated uncertainty (with coverage factor k = 1) for the T34013 chamber calibrated in water is 2.2%-2.4%, whereas it increases to 2.5% and 2.7% for the A20 and T34013 chambers calibrated in air, respectively. The output factors, measured with the PTW chambers, differ by less than 1.1% for any applicator size when compared to the output factors that were measured with the A20 chamber. CONCLUSIONS Measurements using both dosimetric protocols are consistent, once the overall uncertainties are considered. There is also consistency between measurements performed with both chambers calibrated in air. Both the T34013 and A20 chambers have negligible stem effect. Any x-ray surface brachytherapy system, including Esteya, can be characterized using either one of these calibration protocols and ionization chambers. Having less correction factors, lower uncertainty, and based on measurements, performed in closer to clinical conditions, the TRS-398 protocol seems to be the preferred option.
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Affiliation(s)
- C Candela-Juan
- Radiation Oncology Department, La Fe University and Polytechnic Hospital, Valencia 46026, Spain
| | - J Vijande
- Department of Atomic, Molecular, and Nuclear Physics, University of Valencia, Burjassot 46100, Spain and Instituto de Física Corpuscular (UV-CSIC), Paterna 46980, Spain
| | - T García-Martínez
- Radiation Oncology Department, Hospital La Ribera, Alzira 46600, Spain
| | - Y Niatsetski
- Elekta Brachytherapy, Veenendaal 3905 TH, The Netherlands
| | - G Nauta
- Elekta Brachytherapy, Veenendaal 3905 TH, The Netherlands
| | - J Schuurman
- Elekta Brachytherapy, Veenendaal 3905 TH, The Netherlands
| | - Z Ouhib
- Radiation Oncology Department, Lynn Regional Cancer Center, Boca Raton Community Hospital, Boca Raton, Florida 33486
| | - F Ballester
- Department of Atomic, Molecular, and Nuclear Physics, University of Valencia, Burjassot 46100, Spain
| | - J Perez-Calatayud
- Radiation Oncology Department, La Fe University and Polytechnic Hospital, Valencia 46026, Spain and Department of Radiotherapy, Clínica Benidorm, Benidorm 03501, Spain
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Aspradakis MM, Zucchetti P. Acceptance, commissioning and clinical use of the WOmed T-200 kilovoltage X-ray therapy unit. Br J Radiol 2015. [PMID: 26224430 DOI: 10.1259/bjr.20150001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVE The objective of this work was to characterize the performance of the WOmed T-200-kilovoltage (kV) therapy machine. METHODS Mechanical functionality, radiation leakage, alignment and interlocks were investigated. Half-value layers (HVLs) (first and second HVLs) from X-ray beams generated from tube potentials between 30 and 200 kV were measured. Reference dose was determined in water. Beam start-up characteristics, dose linearity and reproducibility, beam flatness, and uniformity as well as deviations from inverse square law were assessed. Relative depth doses (RDDs) were determined in water and water-equivalent plastic. The quality assurance program included a dosimetry audit with thermoluminescent dosemeters. RESULTS All checks on machine performance were satisfactory. HVLs ranged between 0.45-4.52 mmAl and 0.69-1.78 mmCu. Dose rates varied between 0.2 and 3 Gy min(-1) with negligible time-end errors. There were differences in measured RDDs from published data. Beam outputs were confirmed with the dosimetry audit. The use of published backscatter factors was implemented to account for changes in phantom scatter for treatments with irregularly shaped fields. CONCLUSION Guidance on the determination of HVL and RDD in kV beams can be contradictory. RDDs were determined through measurement and curve fitting. These differed from published RDD data, and the differences observed were larger in the low-kV energy range. ADVANCES IN KNOWLEDGE This article reports on the comprehensive and novel approach to the acceptance, commissioning and clinical use of a modern kV therapy machine. The challenges in the dosimetry of kV beams faced by the medical physicist in the clinic are highlighted.
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Affiliation(s)
- Maria M Aspradakis
- Institute of Radiation Oncology, Cantonal hospital of Lucerne, Lucerne, Switzerland
| | - Paolo Zucchetti
- Institute of Radiation Oncology, Cantonal hospital of Lucerne, Lucerne, Switzerland
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Commissioning and periodic tests of the Esteya(®) electronic brachytherapy system. J Contemp Brachytherapy 2015; 7:189-95. [PMID: 26034501 PMCID: PMC4444461 DOI: 10.5114/jcb.2015.51523] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Revised: 04/02/2015] [Accepted: 04/25/2015] [Indexed: 12/05/2022] Open
Abstract
A new electronic brachytherapy unit from Elekta, called Esteya®, has recently been introduced to the market. As a part of the standards in radiation oncology, an acceptance testing and commissioning must be performed prior to treatment of the first patient. In addition, a quality assurance program should be implemented. A complete commissioning and periodic testing of the Esteya® device using the American Association of Physicists in Medicine (AAPM), Groupe Européen de Curiethérapie and the European Society for Radiotherapy & Oncology (GEC-ESTRO) guidelines for linacs and brachytherapy units as well as our personal experience is described in this paper. In addition to the methodology, recommendations on equipment required for each test are provided, taking into consideration their availability and traceability of the detectors. Finally, tolerance levels for all the tests are provided, and a specific frequency for each test is suggested.
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Johnstone CD, LaFontaine R, Poirier Y, Tambasco M. Modeling a superficial radiotherapy X-ray source for relative dose calculations. J Appl Clin Med Phys 2015; 16:5162. [PMID: 26103479 PMCID: PMC5690109 DOI: 10.1120/jacmp.v16i3.5162] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Revised: 01/17/2015] [Accepted: 01/13/2015] [Indexed: 11/25/2022] Open
Abstract
The purpose of this study was to empirically characterize and validate a kilovoltage (kV) X‐ray beam source model of a superficial X‐ray unit for relative dose calculations in water and assess the accuracy of the British Journal of Radiology Supplement 25 (BJR 25) percentage depth dose (PDD) data. We measured central axis PDDs and dose profiles using an Xstrahl 150 X‐ray system. We also compared the measured and calculated PDDs to those in the BJR 25. The Xstrahl source was modeled as an effective point source with varying spatial fluence and spectra. In‐air ionization chamber measurements were made along the x‐ and y‐axes of the X‐ray beam to derive the spatial fluence and half‐value layer (HVL) measurements were made to derive the spatially varying spectra. This beam characterization and resulting source model was used as input for our in‐house dose calculation software (kVDoseCalc) to compute radiation dose at points of interest (POIs). The PDDs and dose profiles were measured using 2, 5, and 15 cm cone sizes at 80, 120, 140, and 150 kVp energies in a scanning water phantom using IBA Farmer‐type ionization chambers of volumes 0.65 and 0.13 cc, respectively. The percent difference in the computed PDDs compared with our measurements range from −4.8% to 4.8%, with an overall mean percent difference and standard deviation of 1.5% and 0.7%, respectively. The percent difference between our PDD measurements and those from BJR 25 range from −14.0% to 15.7%, with an overall mean percent difference and standard deviation of 4.9% and 2.1%, respectively — showing that the measurements are in much better agreement with kVDoseCalc than BJR 25. The range in percent difference between kVDoseCalc and measurement for profiles was −5.9% to 5.9%, with an overall mean percent difference and standard deviation of 1.4% and 1.4%, respectively. The results demonstrate that our empirically based X‐ray source modeling approach for superficial X‐ray therapy can be used to accurately compute relative dose in a homogeneous water‐equivalent medium. They also show limitations in the accuracy of the BJR 25 PDD data. PACS number: 87.55.kh
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Characterization of novel water-equivalent PRESAGE® dosimeters for megavoltage and kilovoltage x-ray beam dosimetry. RADIAT MEAS 2015. [DOI: 10.1016/j.radmeas.2015.02.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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De Deene Y, Skyt PS, Hil R, Booth JT. FlexyDos3D: a deformable anthropomorphic 3D radiation dosimeter: radiation properties. Phys Med Biol 2015; 60:1543-63. [PMID: 25615261 DOI: 10.1088/0031-9155/60/4/1543] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Three dimensional radiation dosimetry has received growing interest with the implementation of highly conformal radiotherapy treatments. The radiotherapy community faces new challenges with the commissioning of image guided and image gated radiotherapy treatments (IGRT) and deformable image registration software.A new three dimensional anthropomorphically shaped flexible dosimeter, further called 'FlexyDos3D', has been constructed and a new fast optical scanning method has been implemented that enables scanning of irregular shaped dosimeters. The FlexyDos3D phantom can be actuated and deformed during the actual treatment. FlexyDos3D offers the additional advantage that it is easy to fabricate, is non-toxic and can be molded in an arbitrary shape with high geometrical precision.The dosimeter formulation has been optimized in terms of dose sensitivity. The influence of the casting material and oxygen concentration has also been investigated. The radiophysical properties of this new dosimeter are discussed including stability, spatial integrity, temperature dependence of the dosimeter during radiation, readout and storage, dose rate dependence and tissue equivalence.
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Affiliation(s)
- Y De Deene
- Department of Engineering, Faculty of Science and Engineering, Macquarie University, Sydney NSW 2109, Australia. Institute of Medical Physics, Faculty of Science, University of Sydney, Sydney, Australia
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Nilsson S, Moutrie Z, Cheuk R, Chan P, Lancaster C, Markwell T, Dawes J, Back P. A unique approach to high-dose-rate vaginal mold brachytherapy of gynecologic malignancies. Brachytherapy 2014; 14:267-72. [PMID: 25466360 DOI: 10.1016/j.brachy.2014.10.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Revised: 09/19/2014] [Accepted: 10/22/2014] [Indexed: 12/16/2022]
Abstract
PURPOSE Patients with cervical and vaginal cancer sometimes have a less straightforward approach for choice of brachytherapy treatment owing to the tumor's location and clinical presentation. The staff at Royal Brisbane & Women's Hospital in Queensland, Australia, is trying to solve this problem by the use of an old technique in a new approach called vaginal molds. With a patient-specific vaginal mold, the appearance of the applicator and the dose distribution can be customized to provide an optimal treatment for each patient. METHODS AND MATERIALS The technique used at the Royal Brisbane & Women's Hospital uses a flexible two-part putty, moulded to the shape of the vagina, in which standard catheters (flexible implant tubes) are incorporated, in a pattern designed to permit a dose distribution more conformal to the target volume. RESULTS The presented technique is efficient and improves the accuracy of a homogeneous target cover and sparing of organs at risk for vaginal mold brachytherapy treatments at our institution. CONCLUSION This technique offers a customizable option when traditional cylindrical- or dome-type applicators cannot be used, or provide inadequate dose coverage. Molds to match the patient anatomy can be created quickly, while allowing flexibility in positioning of catheters to achieve the desired dose distribution.
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Affiliation(s)
- Sanna Nilsson
- Cancer Care Services, Royal Brisbane & Women's Hospital, Brisbane, Australia.
| | - Zoë Moutrie
- Cancer Care Services, Royal Brisbane & Women's Hospital, Brisbane, Australia
| | - Robyn Cheuk
- Cancer Care Services, Royal Brisbane & Women's Hospital, Brisbane, Australia
| | - Philip Chan
- Cancer Care Services, Royal Brisbane & Women's Hospital, Brisbane, Australia
| | - Craig Lancaster
- Cancer Care Services, Royal Brisbane & Women's Hospital, Brisbane, Australia
| | - Tim Markwell
- Radiation Oncology Mater Centre, Brisbane, Australia
| | - Jodi Dawes
- Cancer Care Services, Royal Brisbane & Women's Hospital, Brisbane, Australia
| | - Phil Back
- Cancer Care Services, Royal Brisbane & Women's Hospital, Brisbane, Australia
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Sobolewski M, Haque M. Optimising treatment distance and treatment area for HDR surface mould brachytherapy. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2014; 37:681-9. [PMID: 25293381 DOI: 10.1007/s13246-014-0305-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Accepted: 09/29/2014] [Indexed: 11/29/2022]
Abstract
The purpose of this study was to quantify the effect of treatment area and treatment distance on dose distributions for geometrically optimised surface mould plans in order to provide guidance in choosing treatment parameters and constructing moulds for individual patients. Geometrically optimised plans were generated with a typical brachytherapy planning system and measurements were taken with radiochromic film over depths of 5-32 mm with an (192)Ir high dose rate source. Films were calibrated with a cylindrical geometry technique utilising the (192)Ir source and readout was performed with a flatbed scanner. The rate of dose fall-off about the prescription plane, as well as the magnitude and extent of local dose maxima superficial to the prescription plane, increased with decreasing treatment areas when inter-catheter spacing and treatment distance were kept constant. The dose fall-off was highly dependent on treatment distance, with a 16 % reduction in dose 4 mm superficial to the treatment depth occurring when the distance was increased from 10 to 20 mm while maintaining a 10 mm inter-catheter spacing. The table generated using the measured planar geometry data, can be used as an initial guide for mould construction and planning. The properties of high dose regions near to the catheter plane are highly dependent on the treatment area, which must be considered when normal tissue dose tolerances are a concern. Treatment distance is a key variable influencing the overall dose distribution and should be adjusted as a function of the desired tumour to skin dose ratio, controlled by mould thickness.
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Affiliation(s)
- Matthew Sobolewski
- Riverina Cancer Care Centre, 31 Meurant Avenue, Wagga Wagga, NSW, 2650, Australia,
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