scholarly journals Effect of the thermoplastic masks on dose distribution in the build-up region for photon beams

2016 ◽  
Vol 22 (1) ◽  
pp. 1-4 ◽  
Author(s):  
Michał Półtorak ◽  
Edyta Fujak ◽  
Paweł Kukołowicz
Keyword(s):  
Dose Distribution ◽  
Maximum Dose ◽  
X Rays ◽  
External Radiation ◽  
Medical Systems ◽  
Photon Beams ◽  
Two Photon ◽  
Different Diameters ◽  
Radiation Beams ◽  
Made In

Abstract The aim of the study was to investigate the influence of thermoplastic masks material (Klarity Medical&Equipment Co., Guangzhou, China) with different diameters of holes (ϕ 0.25 cm and ϕ 0.40 cm) on the dose distribution in the build-up region for photon beams. Measurements were made for external radiation beams produced by the linear accelerator (TrueBeam, Varian Medical Systems, Inc., Palo Alto, CA, USA) using the Markus parallel plane ionization chamber and the Unidos electrometer (both from PTW, Freiburg, Germany). Measurements were made in a solid water phantom for two photon energies 6 MV and 15 MV, at 90 cm source to skin distance, for four fields of 5 cm × 5 cm, 10 cm × 10 cm, 15 cm × 15 cm and 20 cm × 20 cm. Compared to the open field, the maximum dose with mask was closer to the surface of the phantom by about 1.4 mm and 1.2 mm for 6 MV and 15 MV X-Rays, respectively. The surface dose increase from 10% to 42% for 6 MV and from 5% to 28% for 15 MV X-Rays.

scholarly journals Experiments on the treatment of animals infected with trypanosomes, by means of atoxyl, vaccines, cold, X-Rays, and leucocytic extract; enumerative methods employed. (preliminary note.)

1911 ◽  
Vol 83 (563) ◽  
pp. 227-234 ◽  
Keyword(s):  
Thick Film ◽  
Maximum Dose ◽  
Sleeping Sickness ◽  
Toxic Action ◽  
X Rays ◽  
Preliminary Note ◽  
Made In ◽  
Marked Benefit

These experiments were conducted with funds given by Sir Edwin During-Lawrence, Bart., for the purpose of testing the effect of cold on disease, and were suggested by Major R. Ross as a part of the studies made in connection with a case of Sleeping Sickness reported upon in an accompanying paper by him and Dr. David Thomson. Although many researches have been made on the effect of atoxyl and other drugs, we believe that these are the first in which that effect has been measured by regular daily counts of the parasites by measured thick film methods. I. Atoxyl . From a study of the patient W. A. at the Royal Southern Hospital by Major R. Ross and D. Thomson, it will be noted that atoxyl failed to be of any marked benefit to the patient, and in the doses administered there was no noticeable trypanocidal action. Various doses of atoxyl are recommended in treatment of human trypanosomiasis, and the patient (W. A.) received 4 grains as a maximum dose. It was impossible in this case to push the drug further, as the patient quickly showed signs of the toxic action of the drug.

Development of a Gel Type Dosimeter for X-Ray Fields

2017 ◽  
Author(s):  
Yutaro Aoki ◽  
Glenn Harvel ◽  
Toshiharu Sakura ◽  
Takeyoshi Sunagawa
Keyword(s):  
Dose Distribution ◽  
Active Agent ◽  
X Rays ◽  
X Ray ◽  
Red Color ◽  
Oxygen Contamination ◽  
Applied Dose ◽  
New Type ◽  
Plastic Containers ◽  
Radiation Beams

In recent years, use of radiation beams or particle beams have been put to practical use for cancer therapy. In cancer radiation therapy, visualization of radiation patterns is absolutely necessary for precisely evaluating the dose distribution. Therefore, gel type or Fricke type dosimeters [1] are considered useful for visualization. In this study, we developed a new type of gel dosimeter using a doped polyvinyl alcohol (PVA) based solution. This gel uses a red color based chemical reaction that occurs when the active agent is separated. Irradiation of the gel with X-rays is sufficient to break the chemical bonds of the active agent. We irradiated different gel samples with X-rays from a Hitachi MBR-1520R-3 source under different configurations to test the gel performance. We used UV-VIS spectrometry to measure the absorbance of transmitted light through the gel. For the active agent, the absorbance is at a peak wavelength of 490 nm. The amount of absorbance is proportional to the number of interactions with X-rays. We irradiated the gel between 0.5Gy-10Gy with visualization of the gel by photography and spectrometry between each irradiation. The spectrometry was performed using a StellarNet Black Comet system observing the absorbance between 300nm and 600nm. The results show that as the X-ray dose increases, the gel transitions from a clear gel to a light pink gel and then to a red gel. All colors are translucent and allow for the passage of light. The first samples were done in clear plastic containers of 250 ml size. The containers were filled with gel to eliminate air and possible oxygen contamination. The second set of experiments repeated the first study but used metallic coins as X-ray shields. The regions covered by the coins were protected from the dose and remained clear. A sharp edge was observed at the edge of the coin. This implies that the gel does not diffuse and hence can represent a dose distribution as long as it is not mixed. The third samples were placed in disposable cells for measurement of absorbance. The absorbance had a peak in the vicinity wavelength of 490nm. The results confirmed the absorbance to be proportional for increasing applied dose. In summary, a color transition gel was developed for use in detecting irradiation dose from X-rays. This technique has potential application for visualization of dose during medical procedures.

scholarly journals Quality Assurance of Dose Distribution of Photon Beam Planning by Anisotropic Analytical Algorithm (AAA)

2013 ◽  
Vol 4 (1) ◽  
pp. 43-49
Author(s):  
M Jahangir Alam ◽  
Syed Md Akram Hussain ◽  
Kamila Afroj ◽  
Shyam Kishore Shrivastava
Keyword(s):  
Quality Assurance ◽  
Treatment Planning ◽  
Dose Distribution ◽  
Maximum Dose ◽  
Photon Beam ◽  
Field Size ◽  
Planning System ◽  
Treatment Planning System ◽  
Anisotropic Analytical Algorithm ◽  
Analytical Algorithm

A three dimensional treatment planning system has been installed in the Oncology Center, Bangladesh. This system is based on the Anisotropic Analytical Algorithm (AAA). The aim of this study is to verify the validity of photon dose distribution which is calculated by this treatment planning system by comparing it with measured photon beam data in real water phantom. To do this verification, a quality assurance program, consisting of six tests, was performed. In this program, both the calculated output factors and dose at different conditions were compared with the measurement. As a result of that comparison, we found that the calculated output factor was in excellent agreement with the measured factors. Doses at depths beyond the depth of maximum dose calculated on-axis or off-axis in both the fields or penumbra region were found in good agreement with the measured dose under all conditions of energy, SSD and field size, for open and wedged fields. In the build up region, calculated and measured doses only agree (with a difference 2.0%) for field sizes > 5 × 5 cm2 up to 25 × 25 cm2. For smaller fields, the difference was higher than 2.0% because of the difficulty in dosimetry in that region. Dose calculation using treatment planning system based on the Anisotropic Analytical Algorithm (AAA) is accurate enough for clinical use except when calculating dose at depths above maximum dose for small field size.DOI: http://dx.doi.org/10.3329/bjmp.v4i1.14686 Bangladesh Journal of Medical Physics Vol.4 No.1 2011 43-49

Effect of ethmoid sinus cavity on dose distribution at interface and how to correct for it: Magnetic field with photon beams

2003 ◽  
Vol 30 (7) ◽  
pp. 1556-1565 ◽  
Author(s):  
Shada J. Wadi-Ramahi ◽  
Damian Bernard ◽  
James C. H. Chu
Keyword(s):  
Magnetic Field ◽  
Dose Distribution ◽  
Ethmoid Sinus ◽  
Photon Beams ◽  
Sinus Cavity

scholarly journals AI INFLUENCE IN COVID-19 DETECTION

2021 ◽  
Vol 23 (07) ◽  
pp. 1116-1120
Author(s):  
Cijil Benny ◽  
Keyword(s):  
Neural Network ◽  
Statistical Analysis ◽  
Convolutional Neural Network ◽  
Case Reports ◽  
Ct Scans ◽  
Data Sets ◽  
X Rays ◽  
Medical Field ◽  
Primary Key ◽  
Made In

This paper is on analyzing the feasibility of AI studies and the involvement of AI in COVID interrelated treatments. In all, several procedures were reviewed and studied. It was on point. The best-analyzing methods on the studies were Susceptible Infected Recovered and Susceptible Exposed Infected Removed respectively. Whereas the implementation of AI is mostly done in X-rays and CT- Scans with the help of a Convolutional Neural Network. To accomplish the paper several data sets are used. They include medical and case reports, medical strategies, and persons respectively. Approaches are being done through shared statistical analysis based on these reports. Considerably the acceptance COVID is being shared and it is also reachable. Furthermore, much regulation is needed for handling this pandemic since it is a threat to global society. And many more discoveries shall be made in the medical field that uses AI as a primary key source.

Procedure in Dose Distribution Measurement of 25-Mev X-Rays

Science ◽  
1950 ◽  
Vol 111 (2889) ◽  
pp. 514-516 ◽  
Author(s):  
J. S. Laughlin ◽  
W. D. Davies
Keyword(s):  
Dose Distribution ◽  
X Rays ◽  
Distribution Measurement

Khảo sát một số đặc tính bức xạ của buồng ion hóa CC13 và diode bán dẫn razor đối với các chùm photon kích thước nhỏ trên máy gia tốc tuyến tính xạ trị Clinac IX

2020 ◽  
Author(s):  
Tu Vu Ngoc
Keyword(s):  
Radiation Field ◽  
Dose Response ◽  
Dose Distribution ◽  
Ionization Chamber ◽  
Field Size ◽  
Photon Beams ◽  
Silicon Diode ◽  
Depth Dose ◽  
The Difference

Purpose: Compare percent depth dose (PDD) and off-center ratio (OCR) measured by the CC13 ionization chamber and the RAZOR silicon diode in small photon beams. Method and Materials: Some dosimetric characteristics, such as PDD, OCR, penumbra and radiation field size, were considered in this study for 2x2, 3x3, and 4x4 cm2 field sizes. We used the CC13 ionization chamber and the RAZOR silicon diode to measure dose distribution with depth along the axis and off-center of the beam. From the results obtained, the team investigated the differences in radiation parameters measured by the two types of probes above. Results: There are significant differences in the radiation parameters investigated for the CC13 ionization chamber and the RAZOR silicon diode, especially the width of penumbra. For PDD curves, the difference is less than 5% from dmax to 30 cm, however the difference becomes greater in the build-up region, which reaches to 33% at the water phatom surface. The width of penumbra measured by CC13 is always larger than that of RAZOR, the ratio of the penumbra width between two detectors is 1.8 and 1.3 for energies of 6 MV and 15 MV, respectively. Conclusion: The RAZOR silicon diode has better dose response than the CC13 ionization chamber for measuring the PDD and the OCR in small photon beams.

Inhomogeneity of Dose Distribution in Animals Subjected to Whole-Body Irradiation with 250-Kvp X-Rays

1964 ◽  
Vol 21 (3) ◽  
pp. 462 ◽  
Author(s):  
Stanley J. Malsky ◽  
Charles G. Amato ◽  
Victor P. Bond ◽  
James S. Robertson ◽  
Bernard Roswit
Keyword(s):  
Dose Distribution ◽  
Whole Body ◽  
X Rays

scholarly journals The excitation of soft X-rays.—II

1928 ◽  
Vol 119 (781) ◽  
pp. 60-83 ◽  
Keyword(s):  
X Rays ◽  
Lower Resistance ◽  
Made In

This paper is a continuation of our former paper with the same title. In our work on iron we were compelled, for technical reasons, into which it is unnecessary to enter, to leave a gap between about 130 and 200 volts. We have since completed that investigation by filling up the gap and have also extended the range from 600 to 720 volts. The first section of the present paper describes the results obtained. The steady deflection method was used and only two important changes were made in the apparatus. By using a new suspension of Wollaston wire for the electrometer, it was found possible to increase the sensibility to 2400 mm. per volt with little loss of steadiness. This enabled either lower filament currents to be used with less consequent likelihood of gas troubles or alternatively to work with a leak of lower resistance across the electrometer quadrants.

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