scholarly journals A Novel Simple Phantom for Verifying the Dose of Radiation Therapy

2015 ◽  
Vol 2015 ◽  
pp. 1-5
Author(s):  
J. H. Lee ◽  
L. T. Chang ◽  
A. C. Shiau ◽  
C. W. Chen ◽  
Y. J. Liao ◽  
...  
Keyword(s):  
Radiation Therapy ◽  
Correction Factor ◽  
Scatter Correction ◽  
Absorbed Dose ◽  
Clinical Tests ◽  
Thermoluminescent Dosimeters ◽  
Water Phantom ◽  
Audit System ◽  
Solid Water ◽  
The Difference

A standard protocol of dosimetric measurements is used by the organizations responsible for verifying that the doses delivered in radiation-therapy institutions are within authorized limits. This study evaluated a self-designed simple auditing phantom for use in verifying the dose of radiation therapy; the phantom design, dose audit system, and clinical tests are described. Thermoluminescent dosimeters (TLDs) were used as postal dosimeters, and mailable phantoms were produced for use in postal audits. Correction factors are important for converting TLD readout values from phantoms into the absorbed dose in water. The phantom scatter correction factor was used to quantify the difference in the scattered dose between a solid water phantom and homemade phantoms; its value ranged from 1.084 to 1.031. The energy-dependence correction factor was used to compare the TLD readout of the unit dose irradiated by audit beam energies with60Co in the solid water phantom; its value was 0.99 to 1.01. The setup-condition factor was used to correct for differences in dose-output calibration conditions. Clinical tests of the device calibrating the dose output revealed that the dose deviation was within 3%. Therefore, our homemade phantoms and dosimetric system can be applied for accurately verifying the doses applied in radiation-therapy institutions.

scholarly journals Dose profile evaluation of a 137Cs source using a solid water phantom

2020 ◽  
Vol 8 (3) ◽  
Author(s):  
Caio Fernando Teixeira Portela ◽  
Thêssa Cristina Alonso ◽  
Arnado Prata Mourão
Keyword(s):  
Visible Light ◽  
Beam Energy ◽  
Maximum Dose ◽  
Absorbed Dose ◽  
Radiochromic Film ◽  
Radiochromic Films ◽  
Water Phantom ◽  
Dose Profile ◽  
Cesium 137 ◽  
Solid Water

The precision in the dose values delivered in irradiation processes is essential for the efficiency and quality control of these processes. Radiochromic films can be used to record doses and the calibration of these films must be performed so that they can be used as dosimeters. The planning and control of the radiation released in a process allows to adjust the desired dose in the irradiated object. The photons in the primary beam interact with the matter of the object and the beam energy is attenuated due to these interactions. The attenuation depends on the characteristics of the beam and the composition of the irradiated matter. When a beam of photons propagates on an object, it tends to deposit more energy close to the surface and after reaching the maximum dose value, it decreases the dose values with depth. The films used in this work are of the Gafchromic External Beam Therapy (EBT) type, insensitive to visible light and can be prepared in places where sunlight and artificial light exists. Like many other dosimeters, which follow certain protocols, radiochromic films can provide an absolute dose measurement. Radiochromic films are characterized by their linearity, reproducibility, uniformity, sensitivity, and stability after irradiation. For the realization of the experiments, a part of the film to be irradiated was removed designated as background (BG). BG represents a piece of radiochromic film that will not change and reflects changes in film absorption in relation to environmental conditions such as temperature, visible light and scanning light, for example and that must be handled from it way that the film radiated. In this work, irradiations of a solid water phantom were performed using a source of cesium-137 with the deposition of a maximum absorbed dose value of 2.0 Gy. The phantom was placed 1,0 m far from the source collimator. Radiochromic films were placed inside the phantom to obtain the depth variation dose profile and axial dose profiles measured at 1.0 cm depth in the phantom. The dose variation profile in depth allowed to verify that the maximum dose value happened at a depth between 10 and 13 mm, very close to the surface due to the beam energy range (keV). The axial profiles presented a flatness of about 9.4 cm with a total field of 12 cm in diameter. 

External Auditing on Absorbed Dose Using a Solid Water Phantom for Domestic Radiotherapy Facilities

2010 ◽  
Vol 28 (1) ◽  
pp. 50 ◽  
Author(s):  
Chang Heon Choi ◽  
Jung-In Kim ◽  
Jong Min Park ◽  
Yang Kyun Park ◽  
Kun-Woo Cho ◽  
...  
Keyword(s):  
Absorbed Dose ◽  
Water Phantom ◽  
Solid Water

scholarly journals Comparison of the radiochromic EBT2 responses for4 MV LINAC in calibration processes

2019 ◽  
Vol 7 (2A) ◽  
Author(s):  
Sabrina Donato Silva ◽  
André L.S Castro ◽  
Thais Melo Mendes ◽  
Luciana B. Nogueira ◽  
Tarcisio Passos Ribeiro Campos
Keyword(s):  
Quality Control ◽  
Calibration Curve ◽  
Absorbed Dose ◽  
Public Health Problem ◽  
Radiochromic Film ◽  
Global Public Health ◽  
Linear Accelerators ◽  
Radiochromic Films ◽  
Water Phantom ◽  
Solid Water

Actually, cancer has gained a larger dimension and become a global public health problem. Radiotherapy (RT) is a neoplasia treatment and RT linear accelerators must undergo a strict dose quality control. Water or solid water phantoms can be used with this intuit. In recent years, radiochromic films with equivalent tissue composition have been widely used as dosimeters in the medical field. In this work the proposal was to analyze two distinct radiochromic film responses in water and solid water phantoms, a LINAC spectrum of 4MV beam. Solid water phantom, water phantom and EBT2 Radiochromic films were set in two distinct process of calibration. Films were exposed to a set of absorbed doses established by distinct monitor units (MU) specified in RT-center. Mathematical relations between the degree of red-intensity from digitized films and the absorbed dose for both methods were established. The coefficients of the polynomial function of the calibration curve were determined from the Origin software. The uncertainty of both processes was analyzed. The efficiency of the two calibration processes was set up. The adjustment of the calibration curve provided the coefficients of the second-order equation that relates the dose absorbed with the optical density of the film. The uncertainty regarding the calibration performed in water and solid water and the dose-error accuracy are in agreement with the literature. Both water and solid water were effective in calibration and can be used in routines of quality-control measurements. The results show that EBT2-radiochromic films are suitable to for dose-calibration in RT.

scholarly journals International recommendations for personalised selective internal radiation therapy of primary and metastatic liver diseases with yttrium-90 resin microspheres

2021 ◽  
Author(s):  
Hugo Levillain ◽  
Oreste Bagni ◽  
Christophe M. Deroose ◽  
Arnaud Dieudonné ◽  
Silvano Gnesin ◽  
...  
Keyword(s):  
Radiation Therapy ◽  
Absorbed Dose ◽  
Steering Committee ◽  
Selective Internal Radiation Therapy ◽  
Internal Radiation ◽  
Selective Internal Radiation ◽  
Internal Radiation Therapy ◽  
Resin Microspheres ◽  
Yttrium 90 ◽  
Strong Agreement

Abstract Purpose A multidisciplinary expert panel convened to formulate state-of-the-art recommendations for optimisation of selective internal radiation therapy (SIRT) with yttrium-90 (90Y)-resin microspheres. Methods A steering committee of 23 international experts representing all participating specialties formulated recommendations for SIRT with 90Y-resin microspheres activity prescription and post-treatment dosimetry, based on literature searches and the responses to a 61-question survey that was completed by 43 leading experts (including the steering committee members). The survey was validated by the steering committee and completed anonymously. In a face-to-face meeting, the results of the survey were presented and discussed. Recommendations were derived and level of agreement defined (strong agreement ≥ 80%, moderate agreement 50%–79%, no agreement ≤ 49%). Results Forty-seven recommendations were established, including guidance such as a multidisciplinary team should define treatment strategy and therapeutic intent (strong agreement); 3D imaging with CT and an angiography with cone-beam-CT, if available, and 99mTc-MAA SPECT/CT are recommended for extrahepatic/intrahepatic deposition assessment, treatment field definition and calculation of the 90Y-resin microspheres activity needed (moderate/strong agreement). A personalised approach, using dosimetry (partition model and/or voxel-based) is recommended for activity prescription, when either whole liver or selective, non-ablative or ablative SIRT is planned (strong agreement). A mean absorbed dose to non-tumoural liver of 40 Gy or less is considered safe (strong agreement). A minimum mean target-absorbed dose to tumour of 100–120 Gy is recommended for hepatocellular carcinoma, liver metastatic colorectal cancer and cholangiocarcinoma (moderate/strong agreement). Post-SIRT imaging for treatment verification with 90Y-PET/CT is recommended (strong agreement). Post-SIRT dosimetry is also recommended (strong agreement). Conclusion Practitioners are encouraged to work towards adoption of these recommendations.

scholarly journals Dosimetric Intercomparison at the Scandinavian Radiation Therapy Centres I. Absorbed Dose Intercomparison

1982 ◽  
Vol 21 (1) ◽  
pp. 1-10 ◽  
Author(s):  
K.-A. Johansson ◽  
L. O. Mattsson ◽  
H. Svensson
Keyword(s):  
Radiation Therapy ◽  
Absorbed Dose

Calculation of the radiation dose absorbed by human biological tissue when using imaging equipment in radiоtherapy

2021 ◽  
pp. 56-59
Author(s):  
Irina M. Lebedenko ◽  
Sergej S. Khromov ◽  
Taras V. Bondarenko ◽  
Evgenij M. Chertenkov
Keyword(s):  
Monte Carlo ◽  
Radiation Therapy ◽  
Biological Tissue ◽  
Electron Accelerator ◽  
Absorbed Dose ◽  
Tube Voltage ◽  
X Ray ◽  
The Monte Carlo Method ◽  
Therapeutic Procedures ◽  
Dose Control

Considered the issues of X-ray dose control during diagnostic and therapeutic procedures using imaging tools. The dose of X-ray radiation from the visualization devices absorbed by the biological tissue of a person was determined when monitoring the position of the patient on the therapeutic table of the electron accelerator before the radiation therapy session. The processes of transmission of photons and electrons through the medium were simulated, and the X-ray spectra were measured. The emission spectrum of the Varian G-242 Rotating Anode X-ray Tube was obtained using an XR-100-CdTe spectrometer. The absorbed dose is calculated by the Monte Carlo method. The absorbed dose in the water phantom at tube voltage up to 80 kV was 0,9–1,5 mGy.

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