Blood Irradiator Research Articles

Characterization of ferrous-xylenol orange-polyvinyl alcohol gel for gamma dosimetry using spectroscopy

Abstract Fricke gel dosimeters are appropriate candidates for gamma dosimetry. Polyvinyl alcohol Fricke gel dosimeters are the most recent introduced gel dosimeters which have low ion diffusion. In this work, samples of ferrous-xylenol orange-polyvinyl alcohol gel dosimeters were prepared and characterized using optical spectroscopy. Using win XCOM program and the elemental composition of the gel, the mass attenuation coefficients for photons were evaluated. The results exhibited that the prepared gel is the nearly radiological blood-, soft tissue- and water-equivalent. The 60Co gamma cell unit was used to irradiate the gel samples. A dose range response was found linear from 10 to 30 Gy and suitable for blood irradiation dosimetry. Additionally, the gel response good repeatability was confirmed by the coefficient of variation calculations. Furthermore, chemical yield of the gel was estimated to be 34.6. The good characteristics of the prepared gel make it appropriate for dosimetry of blood irradiators.

X-rays are as effective as gamma-rays for the sterilization of Glossina palpalis gambiensis Vanderplank, 1911 (Diptera: Glossinidae) for use in the sterile insect technique

An area-wide integrated pest management strategy with a sterile insect technique (SIT) component requires a radiation source for the sterilisation of male insects. Self-contained gamma irradiators, which were exclusively used in past SIT programmes, are now facing increasing constraints and challenges due to stringent regulations. As a potential alternative, new generation high output X-ray irradiators have been proposed. The feasibility of using X-ray irradiators was assessed by comparing the effects of both gamma- and X-ray irradiators on biological parameters of Glossina palpalis gambiensis (Vanderplank, 1911), that are important for SIT applications. The gamma irradiator Foss Model 812 and two X-ray irradiators, the Rad Source 2400 and the blood irradiator Raycell Mk2 were used. Glossina palpalis gambiensis males were exposed to radiation as pupae. A radiation dose of 110 Gy or above induced more than 97% sterility in females that mated with the irradiated males for all the irradiators. Adult emergence rate, flight propensity, survival and mating performance did not differ between gamma- and X-rays irradiators. These results suggest that irradiating pupae with a dose of 110 Gy is optimal for both gamma-and X-ray irradiators used in this study, to achieve a sterility of approximately 99%. Similar research on other tsetse species could gradually phase out the use of gamma-ray irradiators in favour of X-rays irradiators, especially for smaller SIT programmes.

A study on quality control check of dose distribution in blood bags irradiated by 137Cs source blood irradiator by using EBT3 radiochromic film dosimetry

In this study, the dose homogeneity in the blood bags delivered by a137Cs blood irradiator is investigated by using EBT3 radiochromic film dosimetry. The dose delivered to blood bags is an important factor for protection to TA-GVHD patients during transfusion in medicine. To do this, the dose results experimentally determined by EBT3 films were then compared with those of a MCNPX simulation in which the irradiation canister containing the blood bags was irradiated with a MSD Gammacell 3000 Elan. In the simulation, two different irradiation situations were modeled; one is the canister full with blood bags and the other is half-full of blood bags. The simulation dose results showed that when the canister was filled fully with blood bags, a dose of 24.4 ± 0.1 Gy was estimated in the canister center line. When the canister was half-full with the bags, a 28.8 ± 0.1 Gy dose was estimated in the canister center line. Whereas the dose of 31.3 ± 0.6 Gy dose was experimentally determined in the canister center line when the canister was filled (3 blood bags) half full. As a result, the dose homogeneity in the irradiated blood bags can easily checked by means of a two-dimensional EBT3 film dosimetry technique. Hence, this study showed that EBT3 film dosimetry is still powerful method for quality control check of dose homogeneity of any blood bags before it was used in patient.

Absorbed dose evaluation of a blood irradiator with alanine, TLD-100 and ionization chamber

Irradiation of blood bags using X-ray irradiators and dosimetry services are required to ensure uniform dose levels in the range 25–50 Gy to prevent Transfusion Associated Graft versus Host Disease (TA-GvHD). An absorbed dose characterization of a Raycell MK2 X-Irradiator was performed using three different dosimetric systems. Results showed a dosimetric accuracy of the ionization chamber together with the Alanine dosimeter. TLDs measurements exhibited a small overestimation by 4% of the absorbed dose. The Dose Uniformity Ratio (DUR), between maximum and minimum dose levels in the canister, was in good agreement with the manufacturer specifications (≤1.5).

DOSE MAP BLOOD IRRADIATOR DOSIMETRY SYSTEM: CUSTOMIZED BLOOD EQUIVALENT PHANTOM AND GAFCHROMIC EBT-XD FILM

Blood irradiation is done to sterilize and cease donor T-lymphocytes functionality to avoid Transfusion Associated-Graft Versus Host Disease (TA-GVHD). Dose mapping is the primary means of ensuring that the irradiation process is being conducted correctly. The aim of this study is to measure the minimum, maximum and central absorbed gamma radiation dose delivered at the newly customized blood equivalent phantom using a Gafchromic EBT-XD film. A Gammacell 3000 Elan Blood Irradiator with Cesium-137 source was used. To obtain the dose calibration curves, the films were placed at the center of a phantom and irradiated with the dose range from 5 Gy to 35 Gy with one unirradiated film as a control. The dose calibration curve was plotted using red, green and blue channels. While, for the dose mapping measurement, the irradiation exposure of 9.03 minutes was used to deliver a central dose of 25 Gy to the film. The response of the film will be compared with the GC Dose Mapping Report 2022 which used a water equivalent medium as a phantom. For the calibration curve, the red channel of the film was utilized in this study as it had a higher signal than the other channel. The doses obtained at central, minimum and maximum using EBT-XD film with customized blood equivalent phantom were in agreement with that obtained from GC Dose Mapping Report 2022 to be within ±7.6%, ±8.51% and ±9.95% respectively. We concluded that the customized blood equivalent phantom together with EBT-XD film has a potential to map the dose in blood irradiator accurately. The doses obtained from EBT-XD film were in the range of doses needed to inhibit the proliferation of the T-lymphocytes with central, minimum and maximum doses were 26.9 Gy, 17.2 Gy and 35.7 Gy respectively.

Dose mapping in Cesium-137 blood irradiator using novel Ge-doped silica optical fibres in comparison with gafchromic EBT-XD film: A preliminary study

The purpose of dose-mapping in blood irradiation is to ensure radiation dose delivered to the blood bags is within the specified limits of minimum 15 Gy and maximum 50 Gy, thus preventing any blood transfusion-related diseases. In the present study, we investigated the feasibility of novel fabricated germanium-doped (Ge-doped) silica-based optical fibre as a potential passive dosimeter for dose-mapping of a Cesium-137 (Cs-137) gamma blood irradiator. The calibration curve of optical fibres and Gafchromic EBT-XD film was established by irradiating the samples in the dose range from 5 to 35 Gy at the central of a water-equivalent phantom in a dedicated blood irradiator machine. For dose mapping, the fabricated optical fibres and EBT-XD film were irradiated for a gamma exposure of 8 min and 56 s to deliver a central dose of 25 Gy. Thermoluminescence measurements were performed using a Harshaw 3500 TLD reader at a maximum acquisition temperature of 400 °C. The results of optical fibres were compared with EBT-XD film. The absorbed dose obtained from optical fibres shows deviation of within 0.1%–10.4% compared to that of dose of the film. The fabricated optical fibre studied in this work have a good potential as a new passive dosimeter for characterisation and dose mapping of gamma blood irradiator due to its high sensitivity and reproducible characteristics.

A Simulated Annealing optimization technique to obtain uniform dose distribution in gamma irradiators

It is important to achieve dose uniformity in product box irradiated by gamma irradiators. To minimize lateral non-uniformity of absorbed dose, quantified as Dose Uniformity Ratio in a particular plane (DURp), activities of source pencils need to be optimized. In present study, Simulated Annealing technique is used for this purpose and the same is described for a Low-Dose 60Co Blood Irradiator. An in-house computer program is developed that calculates DURp and optimizes the activities of source pencils. The study demonstrates that only the primary component of dose is sufficient to determine DURp. In the Simulated Annealing technique, several cooling parameters are tested and the most effective cooling schedule is selected to obtain optimized activity distribution. An improvement of 22% in DURp value is observed after optimization as compared to each source pencil having the same activity. The methodology described in the paper is efficient as optimization of source activities using a trial-and-error approach will be tedious and time consuming. The optimization methodology described in the study is applicable to any irradiator geometry. However, geometry-specific dose calculation approach should be adapted.

The Gap in Insurance Liability for Blood and Research Gamma Irradiators.

In 2019, a federal contractor accidently breached a 2,900 Ci 137 Cs sealed source while decommissioning it from a University of Washington research building, releasing a single digit curie of its contents. This event contaminated 13 people as well as all seven floors of the research building, which housed the radiation source. Estimates for clean-up costs and lost revenue exceeded $150 million. The magnitude of this cost prompted licensees in possession of such radioactive sources to question whether their insurance coverage is adequate to cover a large-scale incident and if coverage for such exposure even exists. In this article, we identify potential gaps in commercially available insurance policies by evaluating and assessing associated risks, damages, and accountability. While insurance can mitigate the expense associated with remediation, it is unlikely that sufficient limits would exist to fully protect healthcare institutions from direct financial liability in the event that their radioactive sources are implicated in a nuclear, chemical, biological, or radiological (NCBR) (sometimes called CBRN in other literature) mass contamination event. This paper seeks to outline how the risks and liability to healthcare institutions having such gamma irradiators can be reduced significantly by removing them rather than seeking to insure against the cost of remediation in the event of a leak and/or mass contamination. As such, licensees are encouraged to check their policies for the correct coverage and make sure any coverage restriction is removed from their policies. In addition, licensees are also encouraged to explore financial incentives offered by the US government programs to not only dispose of their present gamma irradiator sources at no cost but also to provide financial support to replace them with alternative technologies.

Suitability of Raycell MK2 Blood X-ray Irradiator for the Use in the Sterile Insect Technique: Dose Response in Fruit Flies, Tsetse Flies and Mosquitoes.

The sterile insect technique (SIT) is based on the inundatory field release of a target pest following their reproductive sterilization via exposure to radiation. Until recently, gamma irradiation from isotopic sources has been the most widely used in SIT programs. As isotopic sources are becoming increasingly expensive, especially for small programs, and regulations surrounding their procurement and shipment increasingly strict, irradiation capacity is one of the limiting factors in smaller or newly developing SIT projects. For this reason, the possibility of using X-ray irradiators has been evaluated in the recent decade. The availability of "off-the-shelf" blood X-ray irradiators that meet the technical requirements for insect irradiation can provide irradiation capacity for those SIT projects in which the acquisition of gamma ray irradiators is not feasible. Following the recent technical characterization of a Raycell MK2 X-ray blood irradiator, it was found in this study, that MK2 instruments were suitable for the sterilization of fruit flies, tsetse flies and mosquitoes, inducing comparable, even slightly higher, sterility levels compared to those achieved by gamma ray irradiation. This, together with its estimated processing efficiency, shows that MK2 irradiators are suitable for small- to mid-sized SIT programs.

DOSE MAPPING OF GAMMA IRRADIATION CHAMBER (GIC)

The use of gamma rays to irradiate blood products have been demonstrated to reduce the probability of post-transfusion graft versus host disease. The aim of this study is to investigate the accuracy of a new batch of Gafchromic EBT-XD films to map the homogeneity of gamma radiation dose delivered to the blood bags and identify the lowest and highest levels of radiation exposure to the blood. The Gammacell 3000 Elan Gamma irradiation chamber (GIC) @ Blood Irradiator with Cesium-137 source was used. During the gamma irradiation at an exposure of 8 minutes 51 seconds to deliver a central dose of 25 Gy to the film, the EBT-XD films were placed at the centre of a blood-equivalent phantom. The doses then were measured using dose mapping analysis of Gafchromic EBT-XD film. The responses of EBT-XD films were compared with EBT3 films and GS 300 Dose Mapping Report 2021 prepared by Best Theratronics Dosimetry Laboratory, Canada. Results showed the value of doses obtained from the mapping using EBT-XD were reliable compared with the doses measured in EBT3 film as they were in the range of the acceptable dose ranges for blood irradiation procedures. The mapping with EBT-XD film yielded a minimum dosage of 18 Gy and a maximum exposure of 32 Gy at 8 minutes 51 seconds of irradiation. In conclusion, EBT-XD offered excellent dosimetric characteristics and has a the potential to dose map the blood irradiator.

Replacing high-risk radioactive materials remains a challenge

The medical industry is substituting x-ray sources for cesium-based blood irradiators. Other industries are also exploring alternative technologies.

Potential urban threat after a radiological fire event

An accident involving both fire and radioactive material might eventually deteriorate into a dual-threat situation. Such scenario connects two important consequences: (a) fire damage and (b) radiation health threat. Computational simulations considering hypothetic fire scenarios in hospitals using radioactive material can provide valuable information about such an event. The initial decision in regards to an emergency response should consider the fire consequences and radiation doses distribution in the environment with consequences appearing at different times. While the fire presents an immediate threat, radiation exposure also creates immediate and future concerns. The purpose of this study is to evaluate leukemia risk from a hypothetical radiological fire event in a hospital operating Cs-137 gamma blood irradiator. The simulation in this study used the Hotspot Health Physics software to generate output data such as total effective dose (TED). The data from HotSpot was then used as an input to the leukemia risk equations from Biological Effects of Ionizing Radiation Committee V and VII (BEIR V and VII) models accordingly. Results suggest that the risks are dependent of wind speed and height of release; however, when age and sex are taken into account different outputs are shown. Also, the risk model can be changed from BEIR VII (low doses) to BEIR V (high doses) as radiation doses rise due to its time-dependent behavior. Such change would bring potential impacts on logistics and risk communication.

Characterization and dose-mapping of an X-ray blood irradiator to assess application potential for the sterile insect technique (SIT)

Self-contained gamma irradiators have been extensively used to reproductively sterilize insects for the sterile insect technique (SIT). More recently, the use of X-ray generators has gained attention due to the reduced investment, logistic, regulatory and safety requirements involved in the procurement, transport and operation of these machines compared with gamma irradiators. In this study, we evaluated a commercially available, “off-the-shelf” X-ray blood irradiator and found it suitable for insect irradiation in the frame of the SIT.

Preliminary results on the quality control of blood irradiators using an alanine/electron paramagnetic resonance dosimeter

Approximately 48 medical institutions in South Korea own and use blood irradiators; however, the quality control of blood irradiators is insufficient. This study was conducted to establish quality control procedures for blood irradiators using an alanine dosimeter and to ensure reliability of dosimetry. For dosimetry using alanine dosimeters, measurements were performed using an alanine dosimeter jig developed in this study to ensure dose delivery system reliability. Furthermore, the dose and dose distribution were verified, and the uncertainty was evaluated.

Diacetylene-Based Colorimetric Radiation Sensors for the Detection and Measurement of γ Radiation during Blood Irradiation.

Blood and its cellular components are irradiated by ionizing radiation before transfusion to prevent the proliferation of viable T lymphocytes which cause transfusion associated-graft versus host disease. The immunodeficient patients undergoing chemotherapy for various malignancies are at risk of this disease. The international guidelines for blood transfusion recommend a minimum radiation exposure of 25 Gray (Gy) to the midplane of the blood bag, while a minimum dose of 15 Gy and a maximum dose of 50 Gy should be given to each portion of the blood bag. Therefore, precise dosimetry of the blood irradiator is essential to ensure the adequate irradiation of the blood components. The paper presents the fabrication of diacetylene-based colorimetric film dosimeters for the verification of irradiated doses. The diacetylene analogues are synthesized by tailoring them with different amide-based headgroups followed by their coating to develop colorimetric film dosimeters. Among all the synthesized diacetylene analogues, aminofluorene-substituted diacetylene exhibits the most significant color transition from white to blue color at a minimum γ radiation dose of 5 Gy. The quantitative study of color change is performed by the digitization of the scanned images of film dosimeters. The digital image processing of the developed film dosimeters facilitates rapid dose measurement which enables their facile implementation and promising application in routine blood irradiator dosimetry.

A Game Theoretical Model of Radiological Terrorism Defense

Radiological dispersal devices (RDD) pose a threat to the United States. Healthcare facilities housing high-risk radioactive materials and devices are potentially easy targets for unauthorized access and are vulnerable to malevolent acts of theft or sabotage. The three most attractive candidates for use in RDD considered in this study are: <sup>60</sup>Co (radiosurgery devices), <sup>137</sup>Cs (blood irradiators) and <sup>192</sup>Ir (brachytherapy high dose radiation device). The threat posed by RDDs has led to evaluating the security risk of radioactive materials and defending against attacks. The concepts of risk analysis used in conjunction with game theory lay the foundations of quantitative security risk management. This paper develops a two player non-cooperative one-shot simultaneous defender-attacker game. The defender (healthcare facility) chooses to defend one of the three high-risk radioactive material targets and the attacker (terrorists or adversaries) chooses to attack one of the three high-risk radioactive material targets. A risk-informed approach is used to model players’ payoffs or expected utilities for each choice of strategies. A game-theoretic model (RDD game) captures the strategic interaction between competing players who act rationally to maximize their expected utility. The evaluation of the RDD game results in a von Neuman max-min strategy solution being preferable to a mixed strategy Nash equilibrium solution. The von Neumann max-min strategy solution of the defender defending cobalt and the attacker attacking cesium is found to be the most prescriptive result, thus favoring the current efforts of phasing out cesium blood irradiators and replacing them with alternative technologies. The RDD game not only gives the defender strategic options to budget scarce security resources but also helps healthcare facilities make optimal choices under severe uncertainty about the terrorist threat.

Technical Note: Fricke dosimetry for blood irradiators.

The Fricke dosimeter has been shown to be a viable option as an absorbed dose standard. This work aims to provide the dose distribution in an irradiator container during blood irradiation using Fricke dosimetry. Measurements were performed using a Gammacell Elan 3000 blood irradiator at Hemocenter in Rio de Janeiro, Brazil. A specific phantom was constructed and patented by the authors to perform these measurements. Fricke solution was prepared according to international protocols, and polyethylene bags filled with Fricke solution (n=19) were spatially distributed within the phantom. Control bags were also submitted to the same process, except the irradiation. The irradiation time was calculated to give 25.7Gy to the central portion of the phantom, the same dose used for blood bags. Encouraging results were obtained with an overall uncertainty of 2.1% (k=1). The obtained results were compared with the doses calculated by the physicist from Hemocenter based on parameters provided by the manufacturer. The mean dose delivered to the Fricke bag in the center of the phantom (cavity 2) was 28.7±0.5Gy, which is 12% higher than the planned dose of 25.7Gy. The obtained results showed that the setup (Fricke and phantom) is able to perform dosimetry for blood irradiators. The delivered dose was higher than expected. This highlights the importance in controlling all the parameters during irradiation to ensure the correct dose for all irradiated bags.

Extracorporeal photopheresis in the treatment of the novel coronavirus disease COVID-19 (a case series)

Rationale : Most people infected with SARS-CoV-2 have asymptomatic or minor clinical manifestations and recover without any aggressive therapy. However, there are patient categories in need of specific treatment and those at high risk of severe disease. Control of viremia with antiviral therapy may not be the best therapeutic strategy, since, in addition to substantial toxicity, antiviral agents can suppress the production of antiviral antibodies and disintegrate adoptive immunity against SARS-CoV-2. Due to a high correlation between the symptoms severity in patients with COVID-19 and inflammation, anti-inflammatory corticosteroids have been proposed to treat the disease. However, clinical data do not support the systemic administration of corticosteroids for the treatment of patients with severe COVID-19. Such treatment may have a negative effect due to suppression of the adoptive immune system. In this regard, the development or use of already available of agents that modulate inflammation without compromising the adoptive immune response could be the most effective therapeutic strategy. Aim: To evaluate clinical efficacy and safety of the cell biotherapy technique, the extracorporeal photopheresis (ECP), in the treatment of patients with moderately severe new coronavirus disease COVID-19. Materials and methods : The study included four patients (three women and one man, age 42 to 60 years), with SARS-CoV-2 infection confirmed by gene amplification. All patients had CT-confirmed bilateral multisegmental viral pneumonia (grades > 2, i.e. with 25 to 60% involvement of the lungs). Prior to admission, all patients received antibiotics (azithromycin 500 mg daily and levo-floxacin / amoxicillin clavulanate 500 mg BID) and antipyretics for torpid fever of up to 38.5-39 °C. The outpatient treatment lasted for 8 to 14 days, with signs of progressive respiratory failure. In addition to the moderately severe and torpid course of viral pneumonia, three patients showed hematology test abnormalities, such as hypochromic anemia, leukopenia, leukopenia/lymphopenia, and moderate thrombocytopenia. Three patients had high C-reactive protein (CRP) levels. Inpatient treatment consisted of azithromycin 500 mg daily, levofloxacin 500 mg BID, hydroxychloroquine 200 mg BID, and low molecular weight heparin (enoxaparin 0.4 ml, 4000 anti-Xa IU, s.c. BID). Despite the treatment, the patients showed signs of progressive respiratory failure, with increasing dyspnea and gradual decrease in saturation from 96% to 92%. Isolation of peripheral blood mononuclear cells was done in an intermittent blood separator "Haemonetics MCS+” (USA), with subsequent cell irradiation with an extracorporeal blood irradiator (OKUFKE 320/400-600/650-01 "Yulia”, ZAO NPKF "METOM”, Russia). Ammifurin (ZAO "Pharmcenter VILAR”, Russia) was used as a photosensitizer. Three patients had two ECP sessions with an interval of 24 hours, and one patient had one ECP session. Results: In three patients who had received two ECP sessions, there was a regression of radiographic signs of viral pneumonia from CT2 to CT1 (less than 25% of lung tissue involvement) during the next four days (96 hours). In one patient, the follow-up CT showed resolving pneumonia with less than 5% involvement of the lungs. The patients (n = 3) with baseline high CRP levels showed their normalization at 4 days after two ECP sessions. At 24 hours after a single ECP session, leukocyte count and differential, as well as platelets were restored. In three patients, viral RNA tests within 2 to 4 days after ECP were negative. These results were associated with normalization of body temperature, no further progression of respiratory failure, and a reduction in hospital stay. Conclusion: The use of ECP in 4 patients with moderately severe SARS-CoV-2 infection has contributed to the rapid relief of clinical symptoms, resolution of the inflammation and restoration of respiratory abnormalities in all of them. These observations allow us to consider ECP as an effective and safe method of treatment for moderately severe COVID-19 and a promising adjuvant method in the high-risk patients in order to prevent an unfavorable disease outcome.

Radiation dose verification of an X-ray based blood irradiator using EBT3 radiochromic films calibrated using Gamma Knife machine.

Blood irradiators (BI) initial acceptance testing and routine annual dosimetry checks require radiation dose measurements in order to comply with regulatory requirements. Traditionally thermo-luminescence dosimeters (TLD) have been used to measure the dose. The EBT3 film is reported to be a better dosimeter for low energy X-rays than its predecessors EBT2 and EBT. To the best of our knowledge, the use of EBT3 films to perform dosimetry on X-ray based BI has not been reported yet. We performed routine radiation dosimetry checks using EBT3 films on a new X-ray based BI and compared the results with TLD dosimetry. Calibration films were irradiated with radiation beam from a Co-60 Gamma Knife (GK) radiosurgery machine and, alternatively, using an Ir-192 high dose rate (HDR) brachytherapy device. The films were calibrated to cover a wide dose range from 1 to 40Gy. Such a wide dose range has not been reported yet in BI film dosimetry. We obtained a relative difference of about 6.6% between doses measured using TLD and those measured using EBT3 films. Both irradiation methods using GK or HDR were found to be adequate for the calibration of the EBT3 Gafchromic films. We recommend the use of EBT3 films in routine X-ray based BI dosimetry checks. The presented method takes advantage of available radiotherapy equipment that can be efficiently used for EBT3 films calibration. The method is fast, reproducible and saves valuable medical physicist's time.

Direct quantitative analysis of a cesium pencil in a simulated hot-cell using a remote-LIBS system equipped with a miniature collimator

An on-site remote method for direct analysis of fissionogenic 137Cs in Cs-pencil, which is replacing the traditional 137CsCl powder used in blood irradiator, was developed based on miniature collimator equipped remote-LIBS at 1–1.5 m remote distances.