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Daniel J, Yousif Y, Zifodya J, Hill R. An evaluation of solid state detectors for the relative dosimetry of Kilovoltage x-ray beams. Med Phys 2022; 49:4082-4091. [PMID: 35179232 DOI: 10.1002/mp.15543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 02/04/2022] [Accepted: 02/07/2022] [Indexed: 11/09/2022] Open
Abstract
INTRODUCTION Kilovoltage (kV) x-ray beams are an essential modality in radiotherapy. Solid state detectors are widely available in radiotherapy departments but their use for kV dosimetry has been limited to date. This study aimed to evaluate the dosimetric performance of a range of solid state detectors for kV dosimetry. METHOD Percentage depth doses (PDDs) and Relative Output Factors (ROFs) were measured on an XStrahl 300 unit (XStrahl-Ltd., UK) using 60, 100, 150 and 300 kVp x-ray beams. The fields were defined by circular applicators with field sizes of 2, 5, 8 and 10 cm diameter and square applicators of field sizes 10×10 and 20×20 cm2 . The following PTW dosimeters were used for measurements: Advanced Markus, PinPoint 3D and Semiflex ionization chambers; Photon, Electron and SRS diodes plus the microDiamond detector. All PDDs were normalized at 5 mm depth and ROFs were measured at 3 mm depth to avoid collisions with the end of the applicators. ROFs measured using chambers were corrected for polarity and ion-recombination effects. RESULTS AND DISCUSSION PDD measurements for 60,100 and 150 kVp beam exhibited good agreement between all diodes and the ionization chambers over the entire range of depths except in the first few millimeters near the surface. However, for the 300 kVp, all diode detectors exhibited an over-responding behaviour compared to reference depth dose data measured with the Advanced Markus chamber. Relative output factors with the diodes were higher than the Advanced Markus chamber at low energy, and the magnitude of these differences is inversely proportional to the field sizes. The PTW P diode showed the highest variation of up to 15% in the output factor compared to the Advanced Markus chamber. CONCLUSION This study evaluated the dosimetric performance of a range of solid state detectors in kV relative dosimetry. This study showed that diode detectors are a suitable replacement for ionization chambers for the PDD measurement of low energy kV beams (60-150 kVp) except for the PDD of 60 kVp with the smaller field sizes. However, an over-responding behaviour of diode detectors at 300 kVp beams shows that diode detectors are not suitable for the PDD measurement of high energy kV beams. Generally, all solid state detectors over responded to ROF measurements, indicating that it is not suitable for ROF measurements. In general, both shielded and unshielded diodes produced a similar dosimetric response, which demonstrates that the energy dependence of solid state detectors should be considered before they are used for any kV relative dosimetric measurements. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- John Daniel
- North West Cancer Centre, Tamworth, NSW, Australia
| | | | | | - Robin Hill
- Department of Radiation Oncology, Chris O'Brien Lifehouse, Sydney, Australia.,Institute of Medical Physics, School of Physics, University of Sydney, Australia.,Biomedical Innovation, Chris O'Brien Lifehouse, Missenden Rd, Camperdown, Sydney, Australia
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Roa D, Leon S, Paucar O, Gonzales A, Schwarz B, Olguin E, Moskvin V, Alva-Sanchez M, Glassell M, Correa N, Moyses H, Shankar A, Hamrick B, Sarria GR, Li B, Tajima T, Necas A, Guzman C, Challco R, Montoya M, Meza Z, Zapata M, Gonzales A, Marquez F, Neira R, Vilca W, Mendez J, Hernandez J. Monte Carlo simulations and phantom validation of low-dose radiotherapy to the lungs using an interventional radiology C-arm fluoroscope. Phys Med 2021; 94:24-34. [PMID: 34979431 DOI: 10.1016/j.ejmp.2021.12.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 11/30/2021] [Accepted: 12/27/2021] [Indexed: 11/26/2022] Open
Abstract
PURPOSE To use MC simulations and phantom measurements to investigate the dosimetry of a kilovoltage x-ray beam from an IR fluoroscope to deliver low-dose (0.3-1.0 Gy) radiotherapy to the lungs. MATERIALS AND METHODS PENELOPE was used to model a 125 kV, 5.94 mm Al HVL x-ray beam produced by a fluoroscope. The model was validated through depth-dose, in-plane/cross-plane profiles and absorbed dose at 2.5-, 5.1-, 10.2- and 15.2-cm depths against the measured beam in an acrylic phantom. CT images of an anthropomorphic phantom thorax/lungs were used to simulate 0.5 Gy dose distributions for PA, AP/PA, 3-field and 4-field treatments. DVHs were generated to assess the dose to the lungs and nearby organs. Gafchromic film was used to measure doses in the phantom exposed to PA and 4-field treatments, and compared to the MC simulations. RESULTS Depth-dose and profile results were within 3.2% and 7.8% of the MC data uncertainty, respectively, while dose gamma analysis ranged from 0.7 to 1.0. Mean dose to the lungs were 1.1-, 0.8-, 0.9-, and 0.8- Gy for the PA, AP/PA, 3-field, and 4-field after isodose normalization to cover ∼ 95% of each lung volume. Skin dose toxicity was highest for the PA and lowest for the 4-field, and both arrangements successfully delivered the treatment on the phantom. However, the dose distribution for the PA was highly non-uniform and produced skin doses up to 4 Gy. The dose distribution for the 4-field produced a uniform 0.6 Gy dose throughout the lungs, with a maximum dose of 0.73 Gy. The average percent difference between experimental and Monte Carlo values were -0.1% (range -3% to +4%) for the PA treatment and 0.3% (range -10.3% to +15.2%) for the 4-field treatment. CONCLUSION A 125 kV x-ray beam from an IR fluoroscope delivered through two or more fields can deliver an effective low-dose radiotherapy treatment to the lungs. The 4-field arrangement not only provides an effective treatment, but also significant dose sparing to healthy organs, including skin, compared to the PA treatment. Use of fluoroscopy appears to be a viable alternative to megavoltage radiation therapy equipment for delivering low-dose radiotherapy to the lungs.
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Affiliation(s)
- D Roa
- Department of Radiation Oncology, University of California, Irvine Health, Orange, CA 92868, USA.
| | - S Leon
- Department of Radiology, University of Florida, Gainesville, FL 32610, USA
| | - O Paucar
- Facultad de Ingenieria Electrica y Electronica, Universidad Nacional de Ingenieria, Lima, Peru
| | - A Gonzales
- Facultad de Ciencias, Universidad Nacional de Ingenieria, Lima, Peru
| | - B Schwarz
- Department of Radiology, University of Florida, Gainesville, FL 32610, USA
| | - E Olguin
- Department of Radiology, University of Florida, Gainesville, FL 32610, USA
| | - V Moskvin
- Department of Radiation Oncology, St. Judes Children's Research Hospital, Memphis, TN 38105, USA
| | - M Alva-Sanchez
- Department of Exact and Applied Sciences, University of Health Sciences of Porto Alegre, Porto Alegre, Brazil
| | - M Glassell
- Department of Radiology, University of Florida, Gainesville, FL 32610, USA
| | - N Correa
- Department of Radiology, University of Florida, Gainesville, FL 32610, USA
| | - H Moyses
- Department of Radiation Oncology, University of California, Irvine Health, Orange, CA 92868, USA
| | - A Shankar
- Department of Radiology, University of Florida, Gainesville, FL 32610, USA
| | - B Hamrick
- Environmental Health and Safety, University of California, Irvine Health, Orange, CA 92868, USA
| | - G R Sarria
- University Hospital Bonn, Department of Radiation Oncology, University of Bonn, Bonn, Germany
| | - B Li
- Department of Radiation Oncology, University of California, San Francisco, CA 94115, USA
| | - T Tajima
- Department of Physics and Astronomy, University of California, Irvine, CA 92697, USA
| | - A Necas
- TAE Technologies, 1961 Pauling, Foothill Ranch, CA 92610, USA
| | - C Guzman
- Facultad de Medicina Humana, Universidad Ricardo Palma, Lima, Peru
| | - R Challco
- Facultad de Ciencias, Universidad Nacional de Ingenieria, Lima, Peru
| | - M Montoya
- Facultad de Ciencias, Universidad Nacional de Ingenieria, Lima, Peru
| | - Z Meza
- Facultad de Ciencias, Universidad Nacional de Ingenieria, Lima, Peru
| | - M Zapata
- Facultad de Ciencias, Universidad Nacional de Ingenieria, Lima, Peru
| | - A Gonzales
- Clinica Aliada contra el Cancer, Lima, Peru
| | - F Marquez
- Facultad de Ciencias Físicas, Universidad Nacional Mayor de San Marcos, Lima, Peru
| | - R Neira
- Instituto Nacional de Enfermedades Neoplasicas, Lima, Peru
| | - W Vilca
- Instituto Nacional de Enfermedades Neoplasicas, Lima, Peru
| | - J Mendez
- Facultad de Ciencias Naturales y Matemática, Universidad Nacional del Callao, Callao, Peru
| | - J Hernandez
- HRS Oncology International, Las Vegas, NV 89119, USA
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Breitkreutz DY, Weil MD, Bazalova-Carter M. External beam radiation therapy with kilovoltage x-rays. Phys Med 2020; 79:103-12. [PMID: 33221545 DOI: 10.1016/j.ejmp.2020.11.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 10/03/2020] [Accepted: 11/01/2020] [Indexed: 12/14/2022] Open
Abstract
Kilovoltage (kV) x-rays are most commonly used for diagnostic imaging due to their sensitivity to tissue composition. In radiation therapy (RT), due to their fast attenuation, kV x-rays are typically only used for superficial irradiation of skin cancer and for intra-operative RT (IORT). Recently, however, a number of kV RT techniques have emerged. In this review article, we provide a brief overview of the use of kV x-rays for RT. Various kV x-ray source technologies suitable for RT, such as conventional x-ray tubes as well as novel x-ray sources, are first described. This x-ray source section is then followed by a section on their implementation in terms of clinical, veterinary and preclinical applications. Specifically, IORT, superficial RT and dose enhancement with iodine and gold nanoparticles, as well as microbeam RT and FLASH RT are discussed in this context. Then, a number of kV x-ray RT applications in modeling and proof-of-principle stages, such as breast external beam RT with rotational sources, kilovoltage arc therapy and the BriXS Compton pulsed x-ray sources, are reviewed. Finally, some clinical and economic considerations for the development of kV RT techniques are discussed.
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Roa D, Moyses H, Leon S, Hamrick B, Sarria GR, Li B, Tajima T, Necas A, Guzman C, Paucar O, Gonzales A, Challco R, Montoya M, Arqque Z, Gonzales A, Hernandez J, Drake J, Villane R, Lea J. Dose simulations of an early 20th century kilovoltage pneumonia radiotherapy technique performed with a modern fluoroscope. Med Dosim 2020; 46:74-79. [PMID: 32958360 PMCID: PMC7500403 DOI: 10.1016/j.meddos.2020.08.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 07/30/2020] [Accepted: 08/20/2020] [Indexed: 12/26/2022]
Abstract
To simulate an early 20th century viral pneumonia radiotherapy treatment using modern fluoroscopy and evaluated it according to current dose guidelines. Monte Carlo was used to assess the dose distribution on an anthropomorphic phantom. Critical organs were: skin, breasts, esophagus, ribs, vertebrae, heart, thymus, and spinal cord. A 100 kVp beam with 3 mm Al HVL, 25 × 25 cm2 posterior-anterior (PA) field and 50 cm source-to-surface distance were simulated. Simulations had a resolution of 0.4 × 0.4 × 0.06 cm3 and a 6% uncertainty. Hundred percent dose was normalized to the skin surface and results were displayed in axial, coronal, and sagittal planes. Dose volume histograms were generated in MATLAB for further analysis. Prescription doses of 0.3, 0.5, and 1.0 Gy were applied to the 15% isodose for organ-dose comparison to current tolerances and potential risk of detriment. Ninety-five and ninety-seven percent of the right and left lung volumes, respectively, were well-covered by the 15% isodose line. For the 0.3, 0.5, and 1.0 Gy prescriptions, the maximum skin doses were 2.9, 4.8, and 9.6 Gy compared to a 2.0 Gy transient erythema dose threshold; left/right lung maximum doses were 1.44/1.46, 2.4/2.4, and 4.8/4.9 Gy compared to a 6.5 Gy pneumonitis and 30 Gy fibrosis thresholds; maximum heart doses were 0.5, 0.9, and 1.8 Gy compared to the 0.5 Gy ICRP-recommendation; maximum spinal cord doses were 1.4, 2.3, and 4.6 Gy compared to 7.0 Gy single fraction dose threshold. Maximum doses to other critical organs were below modern dose thresholds. A 100 kVp PA field could deliver a 0.3 Gy or 0.5 Gy dose without risk of complications. However, a 1.0 Gy dose treatment could be problematic. Critical organ doses could be further reduced if more than one treatment field is used.
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Affiliation(s)
- Dante Roa
- Department of Radiation Oncology, University of California, Irvine Health, Orange, CA 92868, USA.
| | - Harry Moyses
- Department of Radiation Oncology, University of California, Irvine Health, Orange, CA 92868, USA
| | - Stephanie Leon
- Department of Radiology, University of Florida, Gainesville, FL 32610, USA
| | - Barbara Hamrick
- Environmental Health and Safety, University of California, Irvine Health, Orange, CA 92868, USA
| | - Gustavo R Sarria
- Department of Radiation Oncology, University Hospital Bonn, University of Bonn, Bonn, Germany
| | - Benjamin Li
- Department of Radiation Oncology, University of California, San Francisco, CA 94115, USA
| | - Toshiki Tajima
- Department of Physics and Astronomy, University of California, Irvine, CA 92697, USA
| | - Ales Necas
- TAE Technologies, Foothill Ranch, CA 92610, USA
| | - Carmen Guzman
- Facultad de Ciencias Naturales y Matematica, Universidad Nacional Federico Villarreal, Lima, Peru
| | - Oliver Paucar
- Facultad de Ingenieria Electrica y Electronica, Universidad Nacional de Ingenieria, Lima, Peru
| | - Alberto Gonzales
- Facultad de Ciencias, Universidad Nacional de Ingenieria, Lima, Peru
| | - Roger Challco
- Facultad de Ciencias, Universidad Nacional de Ingenieria, Lima, Peru
| | - Modesto Montoya
- Facultad de Ciencias, Universidad Nacional de Ingenieria, Lima, Peru
| | - Zintia Arqque
- Facultad de Ciencias, Universidad Nacional de Ingenieria, Lima, Peru
| | | | | | | | | | - Jon Lea
- GE Healthcare, Salt Lake Ciry, UT 84116, USA
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