scholarly journals Quality Assurance with Dosimetric Consistency of a Co-60 Teletherapy Unit

2017 ◽  
Vol 4 (1) ◽  
pp. 88
Author(s):  
Num Prasad Acharya ◽  
Tika Ram Lamichhane ◽  
Bidyapati Jha
Keyword(s):  
Quality Assurance ◽  
Dose Rate ◽  
Radiation Treatment ◽  
Standard Dose ◽  
Dose Delivery ◽  
Radiation Hazards ◽  
Average Output ◽  
Energy Agency ◽  
Actual Output ◽  
Radionuclide Source

<p class="Default">It is essential to know the standard dose rate, output of Co-60 source in the radiation treatment periodically. It is because the over dosage may cause radiation hazards where as under dosage may lead to unsatisfactory treatment of cancer. Present study focused on the radiation standards and dosimetry for the assurance of the quality and verify that the output of the ionizing radiation emitting medical instruments such as Teletherapy Unit (TTU) which should be within ±2% of the stated one. Present study was done as a part of the regularity of quality assurance (QA) of telecobalt radiotherapy unit that includes the dosimetric measurements of Co-60 TTU at Bhaktapur Cancer Hospital (BCH), Bhaktapur per each month from 29 March 2012 to 29 December 2014. The radionuclide source is Co-60 which has been incorporated in TTU, BCH for the purpose of therapeutic treatment of cancer. The Co-60 source decays continuously to Ni-60 (half-life of 5.27 years) with the decrease in its activity and hence the output dose rate. The calculations of actual dose rate of Co-60 TTU were done by the source to surface distance (SSD) technique. It has been concluded that there is a quality assurance management in Co-60 TTU, BCH with the consistency in the average output dose rate obtained by the actual dosimetry values and the expected output values obtained by decay method. The values obtained by actual dosimetry are within ±2% of the expected values so that the deviation of the actual output dose rate from the expected output data lies within the permissible limit as prescribed by International Atomic Energy Agency (IAEA) and International Commission on Radiation Units and Measurement (ICRUM). In conclusion, our study shows a trend towards uniform and better dose delivery from Co-60 TTU, BCH, Nepal</p><p><strong>Journal of Nepal Physical Society</strong><em><br /></em>Volume 4, Issue 1, February 2017, Page: 88-92</p>

Implementation of an in vivo radiochromic film QA procedure

2016 ◽  
Author(s):  
◽  
Jason Stanford
Keyword(s):  
Quality Assurance ◽  
Radiation Treatment ◽  
Radiochromic Film ◽  
In Vivo Dosimetry ◽  
Patient Specific ◽  
Attractive Alternative ◽  
Quality Assurance Procedure ◽  
Imaging Device ◽  
Treatment Techniques

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] Advance treatment techniques, such as IMRT and dynamic conformal arc delivery, are novel radiation treatment procedures at the forefront of accurate and precise radiotherapy. However, the risk of suboptimal treatment resulting in injury is far greater with these techniques due to their complexity. An in vivo quality assurance system is the most appropriate validation of the delivered dose to the patient from these techniques. The intent of this research is to propose an in vivo dosimetry quality assurance procedure using radiochromic film. This research proved that radiochromic in vivo dosimetry is a viable method of detecting spatial patient specific errors in radiotherapy; however, the process is time consuming and not sensitive enough for dosimetric errors associated with weight change. Although time consuming, in vivo radiochromic dosimetry is an attractive alternative for small cancer centers and developing countries without the large startup capital to acquire the electronic portal imaging device necessary for EPID in vivo dosimetry.

scholarly journals Ablation of Thyroid Residues with 30 mCi 131I: A Comparison in Thyroid Cancer Patients Prepared with Recombinant Human TSH or Thyroid Hormone Withdrawal

2002 ◽  
Vol 87 (9) ◽  
pp. 4063-4068 ◽  
Author(s):  
Furio Pacini ◽  
Eleonora Molinaro ◽  
Maria Grazia Castagna ◽  
Francesco Lippi ◽  
Claudia Ceccarelli ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Hormone Therapy ◽  
Dose Rate ◽  
Initial Dose ◽  
Standard Dose ◽  
Basal Serum ◽  
Recombinant Human Tsh ◽  
Thyroid Ablation ◽  
Serum Tsh ◽  
The Eu

The aim of the study was to assess whether stimulation by recombinant human TSH (rhTSH) may be used in patients with differentiated thyroid carcinoma for postsurgical ablation of thyroid remnants using a 30-mCi standard dose of 131I during thyroid hormone therapy. The rate of ablation was prospectively compared in three groups of patients consecutively assigned to one of three treatment arms: in the first arm, patients (n = 50) were treated while hypothyroid (HYPO); in the second arm, patients (n = 42) were treated while HYPO and stimulated in addition with rhTSH (HYPO + rhTSH); in the third arm, patients (n = 70) were treated while euthyroid (EU) on thyroid hormone therapy and stimulated with rhTSH (EU + rhTSH). The outcome of thyroid ablation was assessed by conventional HYPO 131I scan performed in HYPO state 6–10 months after ablation. Basal serum TSH was elevated in the HYPO and HYPO + rhTSH groups. In the EU + rhTSH group, basal serum TSH was 1.3 ± 2.5 μU/ml (range, &lt;0.005–11.9 μU/ml). After rhTSH, serum TSH significantly increased in the HYPO + rhTSH group and the EU + rhTSH group. Basal 24-h radioiodine thyroid bed uptake was 5.8 ± 5.7% (range, 0.2–21%) and 5.4 ± 5.7% (range, 0.2–26%) in the HYPO and HYPO + rhTSH groups, respectively. In the HYPO + rhTSH group, mean 24-h thyroid bed uptake rose to 9.4 ± 9.5% (range, 0.2–46%) after rhTSH (P &lt; 0.0001). The 24-h uptake after rhTSH in the EU + rhTSH group was 2.5 ± 4.3% (range, 0.1–32%), significantly lower (P &lt; 0.0001) than that found in the HYPO and HYPO + rhTSH groups. The rate of successful ablation was similar in the HYPO and HYPO + rhTSH groups (84% and 78.5%, respectively). A significantly lower rate of ablation (54%) was achieved in the EU + rhTSH group. Mean initial dose rate (the radiation dose delivered during the first hour after treatment) was significantly lower in the EU + rhTSH group (10.7 ± 12.6 Gy/h) compared with the HYPO + rhTSH group (48.5 ± 43 Gy/h) and the HYPO group (27.1 ± 42.5 Gy/h). In conclusion, our study indicates that by using stimulation with rhTSH, a 30-mCi standard dose of radioiodine is not sufficient for a satisfactory thyroid ablation rate. Possible reasons for this failure may be the low 24-h radioiodine uptake, the low initial dose rate delivered to the residues, and the accelerated iodine clearance observed in EU patients. Possible alternatives for obtaining a satisfactory rate of thyroid ablation with rhTSH may consist of increasing the dose of radioiodine or using different protocols of rhTSH administration producing more prolonged thyroid cells stimulation.

scholarly journals ESTIMATING PROFIT , COST FUNCTION AND TECHNICAL EFFICIENCIES OF RICE PRODUCTION IN NEJAF FOR SEASON 2016*

2019 ◽  
Vol 50 (5) ◽  
Author(s):  
Al-Mashhdani & Mahmood
Keyword(s):  
Cost Function ◽  
Output Level ◽  
Average Output ◽  
Optimal Output ◽  
Long Run ◽  
Actual Output ◽  
Short Run ◽  
Profit Maximizing ◽  
Economic Price ◽  
The Cost

The aim of this study was to estimate the profit and cost functions as well as economic, price, cost, and technical efficiencies beside the other economic indices at actual, optimal and profit-maximizing output of rice. A random sample of 240 rice  farms in Nejaf province was used during the agricultural season 2016. From efficiency scales of profit function, it was shown that the output quantity had the greatest impact on the profit compared to other variables (average output costs and price). According to the cost function, the optimum output level and the profit- maximizing output  level for the short run were 64.84 tons and 117.4 tons respectively. The lowest price that the farmer can accept was 194.83 thousand dinars / ton. At this price, the producer loss all fixed costs in the short run, hoping that the price of rice will improve in the long run. Net profit was estimated on the basis of actual output, cost minimizing output (optimal) and profit-maximizing output, which amounted to 8084.32, 30852.65 and 45547.5 thousand dinars, respectively. The of technical efficiency were 34%. and the cost efficiency was 0.52. We conclude from the study that economic resources have not been exploited optimally, indicating that actual output is far from optimal output. The study recommends a output policy aimed at increasing economic efficiency and optimizing the use of available resources.

scholarly journals Development of a time-resolved mirrorless scintillation detector

PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0246742
Author(s):  
Wonjoong Cheon ◽  
Hyunuk Jung ◽  
Moonhee Lee ◽  
Jinhyeop Lee ◽  
Sung Jin Kim ◽  
...  
Keyword(s):  
Quality Assurance ◽  
Dose Rate ◽  
Dose Distribution ◽  
Scintillation Detector ◽  
Image Sensor ◽  
Geometric Distortion ◽  
Patient Specific ◽  
Rate Dependency ◽  
Time Resolved ◽  
Dose Profile

Purpose We developed a compact and lightweight time-resolved mirrorless scintillation detector (TRMLSD) employing image processing techniques and a convolutional neural network (CNN) for high-resolution two-dimensional (2D) dosimetry. Methods The TRMLSD comprises a camera and an inorganic scintillator plate without a mirror. The camera was installed at a certain angle from the horizontal plane to collect scintillation from the scintillator plate. The geometric distortion due to the absence of a mirror and camera lens was corrected using a projective transform. Variations in brightness due to the distance between the image sensor and each point on the scintillator plate and the inhomogeneity of the material constituting the scintillator were corrected using a 20.0 × 20.0 cm2 radiation field. Hot pixels were removed using a frame-based noise-reduction technique. Finally, a CNN-based 2D dose distribution deconvolution model was applied to compensate for the dose error in the penumbra region and a lack of backscatter. The linearity, reproducibility, dose rate dependency, and dose profile were tested for a 6 MV X-ray beam to verify dosimeter characteristics. Gamma analysis was performed for two simple and 10 clinical intensity-modulated radiation therapy (IMRT) plans. Results The dose linearity with brightness ranging from 0.0 cGy to 200.0 cGy was 0.9998 (R-squared value), and the root-mean-square error value was 1.010. For five consecutive measurements, the reproducibility was within 3% error, and the dose rate dependency was within 1%. The depth dose distribution and lateral dose profile coincided with the ionization chamber data with a 1% mean error. In 2D dosimetry for IMRT plans, the mean gamma passing rates with a 3%/3 mm gamma criterion for the two simple and ten clinical IMRT plans were 96.77% and 95.75%, respectively. Conclusion The verified accuracy and time-resolved characteristics of the dosimeter may be useful for the quality assurance of machines and patient-specific quality assurance for clinical step-and-shoot IMRT plans.

scholarly journals OC-0272: "Magic phantom" - a quality assurance system for high dose rate brachytherapy

2015 ◽  
Vol 115 ◽  
pp. S139-S140
Author(s):  
A. Espinoza ◽  
M. Petasecca ◽  
I. Fuduli ◽  
A. Howie ◽  
S. Corde ◽  
...  
Keyword(s):  
Quality Assurance ◽  
Dose Rate ◽  
High Dose Rate ◽  
High Dose ◽  
Quality Assurance System ◽  
High Dose Rate Brachytherapy ◽  
Assurance System

scholarly journals A Quality Assurance Protocol for Radiocarbon Dating Laboratories

Radiocarbon ◽  
1990 ◽  
Vol 32 (3) ◽  
pp. 393-397 ◽  
Author(s):  
Austin Long
Keyword(s):  
Quality Assurance ◽  
International Atomic Energy Agency ◽  
Radiocarbon Dating ◽  
Reliable Data ◽  
Atomic Energy ◽  
Quality Assurance Program ◽  
Energy Agency ◽  
Highly Sensitive ◽  
The World

The purpose of this Quality Assurance (QA) protocol is to summarize guidelines that have been accepted by directors of many radiocarbon dating laboratories throughout the world, and by the International Atomic Energy Agency (IAEA). Some laboratories have followed similar procedures successfully for years. Laboratories that carefully adhere to this protocol will produce consistently reliable data that will be comparable in accuracy to all other laboratories following this or any other equally rigorous quality assurance program. This statement does not, however, pertain to samples with 14C activities highly sensitive to method or degree of pretreatment, as pretreatment techniques vary among laboratories.

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