1
|
Diaz-Martinez VD, Cyr M, Devic S, Tomic N, Lewis DF, Enger SA. Investigation of dosimetric characteristics of radiochromic film in response to alpha particles emitted from Americium-241. Med Phys 2024. [PMID: 38767310 DOI: 10.1002/mp.17133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2023] [Revised: 02/15/2024] [Accepted: 03/15/2024] [Indexed: 05/22/2024] Open
Abstract
BACKGROUND In radiotherapy, it is essential to deliver prescribed doses to tumors while minimizing damage to surrounding healthy tissue. Accurate measurements of absorbed dose are required for this purpose. Gafchromic® external beam therapy (EBT) radiochromic films have been widely used in radiotherapy. While the dosimetric characteristics of the EBT3 model film have been extensively studied for photon and charged particle beams (protons, electrons, and carbon ions), little research has been done on α $\alpha$ -particle dosimetry. α $\alpha$ -emitting radionuclides have gained popularity in cancer treatment due to their high linear energy transfer, short range in tissue, and ability to spare surrounding organs at risk, thereby delivering a more localized dose distribution to the tumor. Therefore, a dose-calibration film protocol for α $\alpha$ -particles is required. PURPOSE This study aimed to develop a dose-calibration protocol for the α $\alpha$ -particle emitting radionuclide 241Am, using Monte Carlo (MC) simulations and measurements with unlaminated EBT3 films. METHODS In this study, a MC-based user code was developed using the Geant4 simulation toolkit to model and simulate an 241Am source and an unlaminated EBT3 film. Two simulations were performed: one with voxelized geometries of the EBT3 active volume composition and the other using water. The dose rate was calculated within a region of interest in the voxelized geometries. Unlaminated EBT3 film pieces were irradiated with the 241Am source at various exposure times inside a black box. Film irradiations were compared to a 6-MV photon beam from a Varian TrueBeam machine. The simulated dose rate was used to convert the exposure times into absorbed doses to water, describing a radiochromic-film-based reference dosimetry protocol for α $\alpha$ -particles. The irradiated films were scanned and through an in-house Python script, the normalized pixel values from the green-color channel of scanned film images were analyzed. RESULTS The 241Am energy spectra obtained from the simulations were in good agreement with IAEA and NIST databases, having differences < $<$ 0.516% for the emitted γ $\gamma$ -rays and produced characteristic x-rays and < $<$ 0.006% for the α $\alpha$ -particles. Due to the short range of α $\alpha$ -particles, there was no energy deposition in the voxels outside the active 241Am source region projected onto the film surface. Thus, the total dose rate within the voxels covering the source was 0.847 ± $\pm$ 0.003 Gy/min within the sensitive layer of the film (LiPCDA) and 0.847 ± $\pm$ 0.004 Gy/min in water, indicating that the active volume can be considered water equivalent for the 241Am beam quality. A novel approach was employed in α $\alpha$ -film dosimetry using an exponential fit for the green channel, which showed promising results by reducing the uncertainty in dose estimation within 5%. Although the statistical analysis did not reveal significant differences between the 6-MV photon beam and the α $\alpha$ calibration curves, the dose-response curves exhibited the expected behavior. CONCLUSIONS The developed MC user code simulated the experimental setup for α $\alpha$ -dosimetry using radiochromic film with acceptable uncertainty. Unlaminated EBT3 film is suitable for the dosimetry of α $\alpha$ -radiation at low doses and can be used in conjunction with other unlaminated GafChromic® films for quality assurance and research purposes.
Collapse
Affiliation(s)
- Victor D Diaz-Martinez
- Medical Physics Unit, Department of Oncology, Faculty of Medicine, McGill University, Montréal, Québec, Canada
| | - Mélodie Cyr
- Medical Physics Unit, Department of Oncology, Faculty of Medicine, McGill University, Montréal, Québec, Canada
| | - Slobodan Devic
- Medical Physics Unit, Department of Oncology, Faculty of Medicine, McGill University, Montréal, Québec, Canada
- Lady Davis Institute for Medical Research, Jewish General Hospital, Montréal, Québec, Canada
| | - Nada Tomic
- Medical Physics Unit, Department of Oncology, Faculty of Medicine, McGill University, Montréal, Québec, Canada
- Lady Davis Institute for Medical Research, Jewish General Hospital, Montréal, Québec, Canada
| | | | - Shirin A Enger
- Medical Physics Unit, Department of Oncology, Faculty of Medicine, McGill University, Montréal, Québec, Canada
- Lady Davis Institute for Medical Research, Jewish General Hospital, Montréal, Québec, Canada
- Research Institute of McGill University Health Centre, Montréal, Québec, Canada
| |
Collapse
|
2
|
Farag OF, Kotb OM, Ghazaly ME, El-Sayed NM. Response of the modified GAFCHROMIC EBT2 radiochromic film to DC glow discharge plasma. Sci Rep 2024; 14:2262. [PMID: 38279004 PMCID: PMC10817983 DOI: 10.1038/s41598-024-52628-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 01/22/2024] [Indexed: 01/28/2024] Open
Abstract
The response of the modified GAFCHROMIC EBT2 radiochromic film to DC Oxygen glow discharge plasma was investigated using a flatbed scanner and an UV-Vis spectrophotometer. The film was modified by removing the polyester overlaminate, adhesive, and topcoat layers with a total thickness of 80 µm, and is now referred to as EBT2-M. The EBT2-M films were exposed to DC Oxygen plasma for different durations: 0, 0.5, 1, 2, 3, 4, 7, and 10 min. The exposed films exhibit coloration homogeneity with an average variation of (1.6 ± 0.3) × 10-4 pixel values/µm, irrespective of the applied exposure time. The pixel values of the red-and-green channels and weighted grayscale images decreased exponentially with different sensitivity amounts to [Formula: see text] 39.67, 49.69, and 42.11 min-1, respectively, as the exposure time increased. The two absorption peaks at 580 ± 4 nm and 632 ± 4 nm in the UV-Vis absorption spectra of the exposed GAFCHROMIC EBT2-M radiochromic films are increasing with increasing exposure time up to 4 min, thereafter saturated for prolonged exposure time. The integrated absorbance in the range from 400 to 700 nm is linearly correlated with the exposure time. The indirect and direct optical energy band gaps and Urbach energy of the modified GAFCHROMIC EBT2 film are weakly correlated with the exposure time. These findings suggest the utilization of the modified GAFCHROMIC EBT2 radiochromic film as a novel and simple technique for plasma diagnostics.
Collapse
Affiliation(s)
- Omar F Farag
- Department of Physics, Faculty of Science, Zagazig University, PO 44519, Zagazig, Egypt
| | - Omar M Kotb
- Department of Physics, Faculty of Science, Zagazig University, PO 44519, Zagazig, Egypt.
| | - M El Ghazaly
- Department of Physics, Faculty of Science, Zagazig University, PO 44519, Zagazig, Egypt
| | - Naglaa M El-Sayed
- Department of Physics, Faculty of Science, Zagazig University, PO 44519, Zagazig, Egypt
| |
Collapse
|
3
|
Ji W, Kim JB, Kim JJ. Measurement of low energy beta radiation from Ni-63 by using peeled-off Gafchromic EBT3 film. NUCLEAR ENGINEERING AND TECHNOLOGY 2022. [DOI: 10.1016/j.net.2022.05.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
|
4
|
Mukherjee B, Bhonsle U. A novel evaluation technique for radiochromic films based on cosine-distance analysis: Feasibilities of wide range photon dosimetry and postal intercomparison in lieu of conventional TLD chips. Appl Radiat Isot 2021; 179:110005. [PMID: 34740061 DOI: 10.1016/j.apradiso.2021.110005] [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: 03/08/2021] [Revised: 10/06/2021] [Accepted: 10/25/2021] [Indexed: 12/01/2022]
Abstract
Photon radiation induced decolourisation of radiochromic film changes its optical density. The photon dose is thereby evaluated as a function of optical density. The detection limit of common radiochromic films lies between 1 cGy and 20 Gy. This paper describes a novel evaluation method of radiochromic films using cosine-distance analysis of the RGB-colour vectors instead of conventional optical density measurements using a scanner in transmission mode. This allows extending the detection limit to excess of 40 Gy.
Collapse
Affiliation(s)
| | - Uday Bhonsle
- Gulf International Cancer Centre, PO Box 5882, Al Bhaia, Abu Dhabi, United Arab Emirates
| |
Collapse
|
5
|
Moreira HM, Guerra Liberal FD, McMahon SJ, Prise KM. Characterization of a custom-made 241Am alpha-source for radiobiological studies. Appl Radiat Isot 2021; 177:109931. [PMID: 34488046 DOI: 10.1016/j.apradiso.2021.109931] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 08/15/2021] [Accepted: 08/29/2021] [Indexed: 01/04/2023]
Abstract
A compact in-house alpha particle source has been developed and fully characterized. The irradiation source is a large area, 25 cm2, 5.4 MeV average energy 241Am source, above which a Mylar dish containing a monolayer of target cells can be placed at defined positions. The source uniformity, flux, particle energy and dose rate were determined experimentally. The dose rate to the nucleus at the closest position was 1.57 Gy/min. Furthermore, a 3D printed collimator was tested and found to improve the uniformity of the energy spectra of particles reaching the target. For validation, prostate PC-3 cells were irradiated in our experimental setup with absorbed doses up to 2 Gy and for reference compared with cells irradiated with conventional X-rays with doses up to 8 Gy. The Relative Biological Effectiveness for alpha particles at 10% survival was 3.66± 0.40 agreeing with previously published data. Data presented here show the feasibility of utilising a low-cost alpha-irradiation source for accurate in vitro assays to better understand the radiobiological effects of high LET alpha particles.
Collapse
Affiliation(s)
- Hugo Mr Moreira
- The Patrick G Johnston Centre for Cancer Research, Queen's University of Belfast, 97 Lisburn Road, Belfast, BT9 7AE, United Kingdom
| | - Francisco Dc Guerra Liberal
- The Patrick G Johnston Centre for Cancer Research, Queen's University of Belfast, 97 Lisburn Road, Belfast, BT9 7AE, United Kingdom.
| | - Stephen J McMahon
- The Patrick G Johnston Centre for Cancer Research, Queen's University of Belfast, 97 Lisburn Road, Belfast, BT9 7AE, United Kingdom
| | - Kevin M Prise
- The Patrick G Johnston Centre for Cancer Research, Queen's University of Belfast, 97 Lisburn Road, Belfast, BT9 7AE, United Kingdom
| |
Collapse
|
6
|
Tiwari A, Sunderland J, Graves SA, Strand S, Flynn R. Absorbed dose distributions from beta-decaying radionuclides: Experimental validation of Monte Carlo tools for radiopharmaceutical dosimetry. Med Phys 2020; 47:5779-5790. [PMID: 32955755 DOI: 10.1002/mp.14463] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 06/22/2020] [Accepted: 08/04/2020] [Indexed: 11/05/2022] Open
Abstract
PURPOSE This study aims to experimentally validate the Monte Carlo generated absorbed doses from the beta particles emitted by 90 Y and 177 Lu using radiochromic EBT3 film-based dosimetry. METHODS Line sources of 90 Y and 177 Lu were inserted longitudinally through blocks of low-density polyethylene and tissue-equivalent slabs of cortical bone and lung equivalent plastics. Radiochromic film (Gafchromic EBT3) was laser cut to accommodate orthogonal line sources of radioactivity, and the film was sandwiched intimately between the rectangular blocks to achieve charged particle equilibrium. Line sources consisted of plastic capillary tube of length (13 ± 0.1) cm, with 0.42-mm inner diameter and a wall thickness of 0.21 mm. 90 Y line sources were prepared from a solution of dissolved 90 Y resin microspheres. 177 Lu line sources were prepared from an aliquot of 177 Lu-DOTATATE. Film exposures were conducted for durations ranging from 10 min to 38 h. Radiochromic film calibration was performed by irradiation with 6-MV-bremsstrahlung x rays from a calibrated linear accelerator, in accordance with literature recommendations. Experimental geometries were precisely simulated within the GATE Monte Carlo toolkit, which has previously been used for the generation of dose point kernels. RESULTS The mean percentage difference between measured and simulated absorbed doses were 5.04% and 7.21% for 90 Y and 177 Lu beta absorbed dose in the range of (0.1-10) Gy. Additionally, 1D gamma analysis using a local 10%/1 mm gamma criterion was performed to compare the absorbed dose distributions. The percentage of measurement points passing the gamma criterion, averaged over all tests, was 93.5%. CONCLUSIONS We report the experimental validation of Monte Carlo derived beta absorbed dose distributions for 90 Y and 177 Lu, solidifying the validity of using Monte Carlo-based methods for estimating absorbed dose from beta emitters. Overall, excellent agreement was observed between the experimental beta absorbed doses in the linear region of the radiochromic film and the GATE Monte Carlo simulations demonstrating that radiochromic film dosimetry has sufficient sensitivity and spatial resolution to be used as a tool for measuring beta decay absorbed dose distributions.
Collapse
Affiliation(s)
- Ashok Tiwari
- Department of Radiology, University of Iowa Hospitals and Clinics, 200 Hawkins Dr., Iowa City, IA, 52242-1077, USA.,Department of Physics, University of Iowa, 203 Van Allen Hall, Iowa City, IA, 52242-1479, USA
| | - John Sunderland
- Department of Radiology, University of Iowa Hospitals and Clinics, 200 Hawkins Dr., Iowa City, IA, 52242-1077, USA.,Department of Physics, University of Iowa, 203 Van Allen Hall, Iowa City, IA, 52242-1479, USA
| | - Stephen A Graves
- Department of Radiology, University of Iowa Hospitals and Clinics, 200 Hawkins Dr., Iowa City, IA, 52242-1077, USA.,Department of Radiation Oncology, University of Iowa Hospitals and Clinics, 200 Hawkins Dr., Iowa City, IA, 52242-1089, USA
| | - Sarah Strand
- Department of Radiation Oncology, University of Iowa Hospitals and Clinics, 200 Hawkins Dr., Iowa City, IA, 52242-1089, USA
| | - Ryan Flynn
- Department of Radiation Oncology, University of Iowa Hospitals and Clinics, 200 Hawkins Dr., Iowa City, IA, 52242-1089, USA
| |
Collapse
|
7
|
Santibáñez M, Fuentealba M, Torres F, Vargas A. Experimental determination of the gadolinium dose enhancement in phantom irradiated with low energy X-ray sources by a spectrophotometer -Gafchromic-EBT3 dosimetry system. Appl Radiat Isot 2019; 154:108857. [PMID: 31434044 DOI: 10.1016/j.apradiso.2019.108857] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2018] [Revised: 08/10/2019] [Accepted: 08/12/2019] [Indexed: 01/22/2023]
Abstract
This work reports the experimental determination of dose enhancement produced in phantoms containing target volumes doped with Gadolinium and irradiated with low-energy X-ray beams. EBT3 Gafchromic films were immersed into 5 ml target volumes to simulate tumor filling with 100% ultra-pure water (blank sample) and ultra-pure water infused with Gd solution (Omniscan®) in different concentration (9-24 mg/ml). The dose enhancement due to excitation of Gd K-edge (50.2 keV) was evaluated in terms of the increment in optical density, obtained by a Spectrophotometer-Gafchromic-EBT3 dosimetry system calibrated in terms of the dose-response for 1-8 Gy range. The dose enhancement was evaluated in two condition: a beam quality with spectrum above the absorption edge in a medium with and without Gd; and two beam qualities (above and below the absorption edge) in a medium with a fixed Gd concentration (18 mg/ml). The obtained results confirmed increments in relative dose enhancement according to Gd concentrations up to 18 mg/ml, with a dose enhancement of 1.1 Gy and an average percentage enhancement of 28.4%. For higher values of concentration, the attenuation interaction of the primary beam is more relevant instead of dose enhancement process. On the other hand, the dose enhancement obtained to comparison the spectra above and below the absorption edge, shown results up to 3.3 Gy of enhancement and average percentage enhancement of 88%.
Collapse
Affiliation(s)
- M Santibáñez
- Departamento de Ciencias Físicas, Universidad de La Frontera, F. Salazar, 01145, Temuco, Chile; Centro de Física e Ingeniería en Medicina (CFIM), Facultad de Ingenieria y Ciencias, Universidad de La Frontera, Temuco, Chile.
| | - M Fuentealba
- Departamento de Ciencias Físicas, Universidad de La Frontera, F. Salazar, 01145, Temuco, Chile
| | - F Torres
- Departamento de Ciencias Físicas, Universidad de La Frontera, F. Salazar, 01145, Temuco, Chile
| | - A Vargas
- Departamento de Ciencias Físicas, Universidad de La Frontera, F. Salazar, 01145, Temuco, Chile
| |
Collapse
|
8
|
Lee KH, Shin JY, Kim EH. Measurement of activity distribution in an Am-241 disc source using peeled-off Gafchromic EBT3 films. Appl Radiat Isot 2018; 135:192-200. [PMID: 29413837 DOI: 10.1016/j.apradiso.2018.01.037] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 01/26/2018] [Accepted: 01/26/2018] [Indexed: 11/25/2022]
Abstract
Commercial alpha-emitting sources are fabricated mainly in a disc type. An alpha particle irradiator in Radiation Bioengineering Laboratory at Seoul National University was installed with an Am-241 disc source. Commercial Am-241 disc sources are fabricated by incorporating the radioactive element into a thin substrate layer. Those disc sources are utilized assuming that the radioactive element is uniformly distributed in the active layer of disc sources. In this study, we employed peeled-off Gafchromic EBT3 films to investigate the uniformity of areal radioactivity density over the disc source and to measure the effect of non-uniform activity distribution on dose distribution at the bottom of the cell culture dish positioned in a varying distance from the source. The measurements with the peeled-off EBT3 films informed that the areal activity density in the disc source differed by up to approximately 45% from the average. However, the inhomogeneous Am-241 distribution in a disc source did not affect the radial distribution of fluence rate at the inner bottom of cell dish when the dish is apart from the source sufficiently. The dose distribution measured with an EBT3 film nearly accorded with that obtained by Monte Carlo simulation assuming the uniform Am-241 activity distribution in the active layer of the disc source. Finally, the dose to a single-cell layer of 5 μm in a nominal thickness was obtained by Monte Carlo simulation assuming a uniform Am-241 activity distribution in the disc source at distances of 20 and 30 mm from the source. The cellular dose estimates were higher than the film dose estimates at all radial distances. The cellular dose decreased with an increasing radial distance from the center to a smaller extent than the EBT3 film dose did.
Collapse
Affiliation(s)
- Kwang-Ho Lee
- Department of Nuclear Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Ji-Yong Shin
- Department of Nuclear Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Eun-Hee Kim
- Department of Nuclear Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea.
| |
Collapse
|
9
|
Quality assurance of alpha-particle dosimetry using peeled-off Gafchromic EBT3 ® film. Radiat Phys Chem Oxf Engl 1993 2016. [DOI: 10.1016/j.radphyschem.2016.04.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
|