OSL PROPERTIES IN VARIOUS FORMS OF KCl AND NaCl SAMPLES AFTER EXPOSURE TO IONIZING RADIATION

2018 ◽  
Vol 184 (1) ◽  
pp. 90-97 ◽  
Author(s):  
Renata Majgier ◽  
Christopher L Rääf ◽  
Arkadiusz Mandowski ◽  
Christian Bernhardsson
Keyword(s):  
Radiation Dosimetry ◽  
Absorbed Dose ◽  
Test Dose ◽  
Optically Stimulated Luminescence ◽  
High Reproducibility ◽  
Signal Stability ◽  
Sensitivity Changes ◽  
Potential Use ◽  
Fading Phenomena

Abstract The aim of this work was to investigate the optically-stimulated luminescence (OSL) properties of potassium chloride (KCl) and its potential use in radiation dosimetry. The optimal condition for OSL readout with blue light stimulation were designated using a commercially available Risø TL/OSL reader. KCl was studied in three sample forms: crystals, powder and pellets. The following OSL characteristics were determined: signal reproducibility, OSL measurement-induced sensitivity changes, temperature dependence of OSL and signal stability over time. The results show a high reproducibility of KCl samples and strong sensitivity changes, which can be corrected for by using a test-dose. The long-term OSL studies confirmed the occurrence of both inverse fading and fading phenomena in KCl. In addition, a comparison with corresponding measurements using sodium chloride (NaCl) were carried out. Although it was confirmed that NaCl is more suitable for dosimetry, there might be benefits of combining NaCl with KCl for more accurate absorbed dose determinations.

scholarly journals NaCl pellets for prospective dosimetry using optically stimulated luminescence: Signal integrity and long-term versus short-term exposure

2020 ◽  
Vol 59 (4) ◽  
pp. 693-702
Author(s):  
Lovisa Waldner ◽  
Christopher Rääf ◽  
Christian Bernhardsson
Keyword(s):  
Absorbed Dose ◽  
Cost Effective ◽  
Optically Stimulated Luminescence ◽  
Preheat Temperature ◽  
Luminescence Signal ◽  
Chronic Radiation ◽  
Short Term Exposure ◽  
Signal Fading ◽  
Signal Yield

Abstract Optically stimulated luminescence (OSL) signal properties of pellets from three types of NaCl (two household salts and one analytical grade salt) were investigated for their use in prospective dosimetry. Special attention was given to the OSL signal behaviour with time. The readout protocol was optimised in terms of preheat temperature, and the OSL signal yield of the NaCl pellet with time as well as the fading of the OSL signal with time was investigated. The effects of acute and chronic irradiations were compared. Irradiations and readout were performed using a Risø TL/OSL reader (TL/OSL-DA-15, DTU Nutech, Denmark). The optimal preheat temperature was determined to be 100 ºC, yielding OSL signals similar to a 1 h pause before OSL signal readout. There was no OSL signal fading observed as a function of time, but a decrease in the OSL signal yield of the NaCl pellets with time resulted in an apparent inverse fading when converting the OSL signal to an absorbed dose. For chronic radiation exposures of up to five weeks, the sensitivity of the NaCl pellets was found to be stable. The results of this study show that the use of NaCl pellets for prospective dosimetry is a promising, cost-effective, and accessible complement to commercially available alternatives for accurate absorbed dose determinations.

scholarly journals Changes in natural OSL sensitivity during single aliquot regeneration procedure and their implications for equivalent dose determination

2011 ◽  
Vol 38 (3) ◽  
pp. 231-241 ◽  
Author(s):  
Ashok Singhvi ◽  
Stephen Stokes ◽  
Naveen Chauhan ◽  
Yogesh Nagar ◽  
Manoj Jaiswal
Keyword(s):  
Test Dose ◽  
Depositional Environments ◽  
Optically Stimulated Luminescence ◽  
Natural Quartz ◽  
Measurement Systems ◽  
Dose Determination ◽  
Saturation Intensity ◽  
Regeneration Procedure ◽  
Single Grain ◽  
Sensitivity Changes

Abstract Measurement of low temperature (90°C–120°C) Thermoluminescence (TL) sensitivity of natural quartz samples subjected to pre-heating and optical stimulation indicate that significant sensitivity changes can occur during measurement of the natural Optically Stimulated Luminescence (OSL). During the measurement of natural signal, the luminescence sensitivity of samples can change by 40%. The sensitivity changes both during the initial preheat and the measurement of natural OSL. The currently used version of Single Aliquot Regeneration (SAR) protocol measures and corrects for the sensitivity changes after preheat and readout of natural OSL. However, it does not take into account the changes in sensitivity during the readout of the natural signal. We therefore developed a correction procedure so that both the natural and the regenerated OSL intensities can be measured and plotted with the same sensitivity and suggest that in the absence of such a correction, a considerable fraction of the SAR based ages could have systematic errors. The correction for the sensitivity is based on the use of sensitivity of 110°C TL quartz peak, which is correlated to OSL signal (Murray and Roberts, 1998). The use of 110°C peak provides a reasonable measure of the changes in OSL sensitivity of quartz. A modified Natural Sensitivity Corrected-SAR (NSC-SAR) procedure, that comprises the measurement of, 1) the TL intensity of 110°C peak for a test dose on sample as received (i.e. natural sample) and, 2) the sensitivity of the 110°C peak of the same sample after the preheat and read out of the natural OSL, is proposed. This ratio, termed as Natural Correction Factor (NCF), then provides a way to correct for sensitivity changes. Results on samples from diverse depositional environments indicated that the NSC-SAR consistently (without exception) provided improved distribution in paleodoses i.e. a lower scatter compared to the standard SAR protocol. In addition, the use of this protocol also resolved anomalous cases where the intensity of natural OSL was significantly above the saturation intensity of the regenerated OSL. Implicitly, this study implies a caution on the use of palaeodoses obtained from single grains as such a correction is not possible in the currently used automated single grain OSL measurement systems. The only way now on will be to analyze aliquots with only a grain on them.

Treatment and secondary prevention of venous thromboembolism in cancer patients

2012 ◽  
Vol 03 (03) ◽  
pp. 121-125
Author(s):  
I. Pabinger ◽  
C. Ay
Keyword(s):  
Clinical Trials ◽  
Venous Thromboembolism ◽  
Cancer Patients ◽  
Oral Anticoagulants ◽  
Factor Xa ◽  
New Oral Anticoagulants ◽  
Phase Iii ◽  
Patients With Cancer ◽  
Potential Use

SummaryCancer is a major and independent risk factor of venous thromboembolism (VTE). In clinical practice, a high number of VTE events occurs in patients with cancer, and treatment of cancerassociated VTE differs in several aspects from treatment of VTE in the general population. However, treatment in cancer patients remains a major challenge, as the risk of recurrence of VTE as well as the risk of major bleeding during anticoagulation is substantially higher in patients with cancer than in those without cancer. In several clinical trials, different anticoagulants and regimens have been investigated for treatment of acute VTE and secondary prophylaxis in cancer patients to prevent recurrence. Based on the results of these trials, anticoagulant therapy with low-molecular-weight heparins (LMWH) has become the treatment of choice in cancer patients with acute VTE in the initial period and for extended and long-term anticoagulation for 3-6 months. New oral anticoagulants directly inhibiting thrombin or factor Xa, have been developed in the past decade and studied in large phase III clinical trials. Results from currently completed trials are promising and indicate their potential use for treatment of VTE. However, the role of the new oral thrombin and factor Xa inhibitors for VTE treatment in cancer patients still has to be clarified in further studies specifically focusing on cancer-associated VTE. This brief review will summarize the current strategies of initial and long-term VTE treatment in patients with cancer and discuss the potential use of the new oral anticoagulants.

scholarly journals Biodistribution and internal radiation dosimetry of a companion diagnostic radiopharmaceutical, [68Ga]PSMA-11, in subcutaneous prostate cancer xenograft model mice

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Su Bin Kim ◽  
In Ho Song ◽  
Yoo Sung Song ◽  
Byung Chul Lee ◽  
Arun Gupta ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Radiation Dosimetry ◽  
Xenograft Model ◽  
Absorbed Dose ◽  
Patient Specific ◽  
Internal Radiation ◽  
Washout Phase ◽  
Heterogeneous Tissue ◽  
Organ Level ◽  
Reported Data

Abstract[68Ga]PSMA-11 is a prostate-specific membrane antigen (PSMA)-targeting radiopharmaceutical for diagnostic PET imaging. Its application can be extended to targeted radionuclide therapy (TRT). In this study, we characterize the biodistribution and pharmacokinetics of [68Ga]PSMA-11 in PSMA-positive and negative (22Rv1 and PC3, respectively) tumor-bearing mice and subsequently estimated its internal radiation dosimetry via voxel-level dosimetry using a dedicated Monte Carlo simulation to evaluate the absorbed dose in the tumor directly. Consequently, this approach overcomes the drawbacks of the conventional organ-level (or phantom-based) method. The kidneys and urinary bladder both showed substantial accumulation of [68Ga]PSMA-11 without exhibiting a washout phase during the study. For the tumor, a peak concentration of 4.5 ± 0.7 %ID/g occurred 90 min after [68Ga]PSMA-11 injection. The voxel- and organ-level methods both determined that the highest absorbed dose occurred in the kidneys (0.209 ± 0.005 Gy/MBq and 0.492 ± 0.059 Gy/MBq, respectively). Using voxel-level dosimetry, the absorbed dose in the tumor was estimated as 0.024 ± 0.003 Gy/MBq. The biodistribution and pharmacokinetics of [68Ga]PSMA-11 in various organs of subcutaneous prostate cancer xenograft model mice were consistent with reported data for prostate cancer patients. Therefore, our data supports the use of voxel-level dosimetry in TRT to deliver personalized dosimetry considering patient-specific heterogeneous tissue compositions and activity distributions.

DEVELOPMENT OF NACL-BASED OPTICALLY STIMULATED LUMINESCENT PHOSPHORS FOR THE POSSIBLE APPLICATIONS IN DOSIMETRY

2020 ◽  
Vol 192 (1) ◽  
pp. 27-35
Author(s):  
S U Gaikwad ◽  
R R Patil ◽  
M S Kulkarni ◽  
C M Dudhe ◽  
S V Moharil
Keyword(s):  
Dose Response ◽  
Radiation Dosimetry ◽  
Optically Stimulated Luminescence ◽  
Signal Loss ◽  
Highly Sensitive ◽  
Very High

Abstract New highly sensitive optically stimulated luminescent phosphors with NaCl moiety and dopants Ca,Cu,P/Mg,Cu,P are developed. These phosphors show very high optically stimulated luminescence (OSL) sensitivity. The dose response for NaCl:Ca,Cu,P is linear up to 1.2 Gy and for NaCl:Mg,Cu,P is slightly sub linear from 0.2 Gy. These phosphors show 30% fading during first 4 and later signal gets stabilised with no further signal loss. These sensitive phosphors will find applications in radiation dosimetry using OSL.

scholarly journals A comparison of in-air and in-water calibration of a dosimetry system used for radiation dose assessment in cancer therapy

2010 ◽  
Vol 25 (1) ◽  
pp. 51-54 ◽  
Author(s):  
Waheed Arshed ◽  
Khalid Mahmood ◽  
Ikramullah Qazi ◽  
Asad Ullah ◽  
Perveen Akhter ◽  
...  
Keyword(s):  
Radiation Dosimetry ◽  
Absorbed Dose ◽  
Dose Assessment ◽  
Dose Delivery ◽  
Air Kerma ◽  
Tissue Equivalent ◽  
Dosimetry System ◽  
Irradiation Geometry ◽  
Radiation Dose Assessment ◽  
Absorbed Dose To Water

An accurate calibration of the therapy level radiation dosimetry system has a pivotal role in the accuracy of dose delivery to cancer patients. The two methods used for obtaining a tissue equivalent calibration of the system: air kerma calibration and its conversion to a tissue equivalent value (absorbed dose to water) and direct calibration of the system in a water phantom, have been compared for identical irradiation geometry. It was found that the deviation between the two methods remained within a range of 0% to ?1.7% for the PTW UNIDOS dosimetry system. This means that although the recommended method is in-water calibration, under exceptional circumstances, in-air calibration may be used as well.

Treatment and secondary prevention of venous thrombo -embolism in cancer patients

2012 ◽  
Vol 32 (02) ◽  
pp. 139-144 ◽  
Author(s):  
I. Pabinger ◽  
C. Ay
Keyword(s):  
Clinical Trials ◽  
Cancer Patients ◽  
Oral Anticoagulants ◽  
Initial Period ◽  
Factor Xa ◽  
Secondary Prophylaxis ◽  
Phase Iii ◽  
Patients With Cancer ◽  
Potential Use

SummaryCancer is a major and independent risk factor of venous thromboembolism (VTE). In clinical practice, a high number of VTE events occurs in patients with cancer, and treatment of cancer-associated VTE differs in several aspects from treatment of VTE in the general population. However, treatment in cancer patients remains a major challenge, as the risk of recurrence of VTE as well as the risk of major bleeding during anticoagulation is substantially higher in patients with cancer than in those without cancer. In several clinical trials, different anticoagulants and regimens have been investigated for treatment of acute VTE and secondary prophylaxis in cancer patients to prevent recurrence. Based on the results of these trials, anticoagulant therapy with low-molecular-weight heparins (LMWH) has become the treatment of choice in cancer patients with acute VTE in the initial period and for extended and long-term anticoagulation for 3–6 months. New oral anti-coagulants directly inhibiting thrombin or factor Xa, have been developed in the past decade and studied in large phase III clinical trials. Results from currently completed trials are promising and indicate their potential use for treatment of VTE also in cancer patients. However, the role of the new oral thrombin and factor Xa inhibitors for VTE treatment in cancer patients still has to be clarified in further studies specifically focusing on cancer-associated VTE. This brief review will summarize the current strategies of initial and long-term VTE treatment in patients with cancer and discuss the potential use of the new oral anticoagulants.

scholarly journals The Potential Use of Drones for Tourism in Crises: A Facility Location Analysis Perspective

2020 ◽  
Vol 13 (10) ◽  
pp. 246
Author(s):  
Shiva Ilkhanizadeh ◽  
Mahmoud Golabi ◽  
Siamand Hesami ◽  
Husam Rjoub
Keyword(s):  
Open Space ◽  
Sustainable Growth ◽  
Mixed Integer ◽  
Historic Sites ◽  
Tourist Attractions ◽  
Innovative Products ◽  
Potential Use ◽  
Do So

Considering the recent lockdowns and travel bans due to COVID-19, novel tourism strategies are necessary to face the increasing need for innovative products and services and to ensure long-term sustainable growth. This study looks into the potential use of drones in providing online virtual tours of open-space tourist attractions. To do so, a novel mixed-integer linear mathematical model is developed to optimally determine the number and location of required facilities and the number of drones assigned to each center. The model is applied to a case study of Rome by selecting six historic sites as the tourist attractions and considering several candidate locations for establishing the facilities. The results of different potential scenarios imply that the project is profitable, even if the demand for virtual tours is low.

scholarly journals Typhoid Conjugate Vaccines and Enteric Fever Control: Where to Next?

2020 ◽  
Vol 71 (Supplement_2) ◽  
pp. S185-S190
Author(s):  
A Duncan Steele ◽  
Megan E Carey ◽  
Supriya Kumar ◽  
Calman A MacLennan ◽  
Lyou-Fu Ma ◽  
...  
Keyword(s):  
Health Impact ◽  
World Health ◽  
Surveillance Systems ◽  
Conjugate Vaccines ◽  
Immunization Strategies ◽  
Global Demand ◽  
Health Organization ◽  
Global Agenda ◽  
Potential Use

Abstract After the unprecedented success and acceleration of the global agenda towards typhoid fever control with a strong World Health Organization recommendation and the approval of funding from Gavi, the Vaccine Alliance (Gavi), for the use of a new typhoid conjugate vaccine (TCV), we should turn our minds to the challenges that remain ahead. Despite the evidence showing the safety and clinical efficacy of TCV in endemic populations in developing countries, we should remain vigilant and explore hurdles for the full public health impact of TCV, including vaccine supply for the potential global demand, immunization strategies to optimize the effectiveness and long-term protection provided by the vaccines, potential use of TCV in outbreak settings, and scenarios for addressing chronic carriers. Finally, challenges face endemic countries with poor surveillance systems concerning awareness of the need for TCV and the extent of the issue across their populations, and how to target immunization strategies appropriately.

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