Actual Radiation Dose Research Articles

Impact of the COVID-19 Infection on Head and Neck Cancer Treatment During Hospitalization.

Objective The after-effects of coronavirus disease 2019 (COVID-19) infection are still unknown; therefore, we investigate the possibility that COVID-19 may interrupt cancer treatment and impact prognosis. Methods We examined the characteristics, prognosis, and changes in treatment options before and after COVID-19 in 11 head and neck cancer patients who were infected with COVID-19 after admission for cancer treatment at Gifu University Hospital. These patients were compared to 110 patients unaffected by COVID-19 during the same period. To identify the effects of COVID-19 on the cancer treatment sequence, we examined the rates of overall survival, progression-free survival, and completion, as well as radiation dosage in radiotherapy and cisplatin dosage in chemoradiotherapy. Results All 11 patients with COVID-19 had their planned cancer treatment postponed or interrupted. There was no significant difference in overall or progression-free survival compared to patients without COVID-19. Notably, only 3/6 of the COVID-19-affected patients completed radiotherapy compared to 42/46 unaffected patients. The ratio of actual radiation dose to planned dose was significantly impaired in COVID-19 affected patients group (98.3% vs. 88.6%). Cisplatin dosage in chemoradiation was not significantly different in either the radical (100 mg/m2, every three weeks) or adjuvant (40 mg/m2, every one week) treatment groups. Conclusion COVID-19 infection in head and neck cancer patients had no apparent impact on cancer prognosis. However, when restricted to irradiation, the treatment completion rate and the ratio of planned to actual dose decreased significantly, underscoring the impact of COVID-19 infection on cancer treatment. The difference in irradiation may affect the success of patients' treatment going forward, and it should be explored whether irradiation can be continued without delay.

An Observational Dosimetric Study in Definitively Treated Primary Head and Neck Cancers: To Assess the Effect of Weight Loss and Change in Lateral Neck Dimensions on the Difference Between Dose Planned and Received by the Parotid(s) and Correlation with Adaptive Radiation Therapy

The head and neck cancer (HNC) literature is rife with reports of differences in planned versus actual radiation doses to the parotid gland (PG) due to changes in anatomy during the course of radiation therapy. We prospectively studied and quantified changes in planned and delivered doses due to weight loss and changes in lateral neck dimensions. Sixty patients were enrolled in this prospective non-randomized observational study. The inclusion criterion was having a newly diagnosed, histologically proven squamous cell carcinoma of HNC. Weight loss (WL) and change in lateral neck dimensions (LND) were assessed weekly, and new hybrid plans were generated using interval replanning CT scans. Dose variations were monitored and extrapolated for replanning CT scans and correlated with WL and change in LND. The Pearson correlation coefficients for WL and difference in Dmean of ipsilateral and contralateral PG was 0.3292 (P = .0124) and 0.4232 (P = .0010), respectively. There was significantly higher change in the Dmean of bilateral PG (Ipsilateral(I) > contralateral(C)) in patients who experienced WL of >5%. Change in LND correlated with difference in Dmean of ipsilateral PG at 0.4829 (P = .0001) and difference in D50 at 0.4146 (P < .0013). Contralateral PG correlated with difference in Dmean at 0.5952 (P < .0001). The difference in Dmean for ipsilateral PG was 1.8535 Gy for those showing reduction in LND of >1 cm compared with 0.8596 Gy (P = .0091) for those who had ≤1 cm reduction in LND. Either WL of >5% or reduction in LND of >1 cm can be used as an external parameter to help select patients who might benefit most from replanning and adaptive radiation therapy.

Tempered glass as a thermoluminescent medium for retrospective dosimetry

Globally, the use of nuclear facilities and the potential risks associated with the dispersal of ionizing radiation due to natural disasters or technical failures are on the rise. These risks can have severe consequences for the environment and all living organisms, particularly humans. There is currently no practical method available to accurately estimate the radiation doses received by the surrounding areas and individuals in such situations. To address this issue, retrospective dosimetry can be employed to estimate the actual radiation dose, followed by the implementation of remediation techniques. Considering this need, tempered glass, which is commonly used as a screen protector for smartphones by the general public, has been identified as a promising medium for retrospective dosimetry. The present study aimed to investigate the thermoluminescence (TL) properties of six different types of tempered glass subjected to 60Co gamma rays, specifically examining the TL dose response, linearity, repeatability, and fading. Among the various glass samples tested, HD anti-peep tempered glass demonstrates a highly linear dose-response and the greatest dose sensitivity within the examined dose range of 2–50 Gy. Additionally, the HD anti-peep tempered glass exhibits minimal loss of TL yield (∼23%) at 28 days post-irradiation, making it particularly suitable for use as a retrospective dosimeter.

Gamma irradiation of eggplant seeds influences plant growth, yield and nutritional profile in M1 generation

The study examines agromorphological traits and nutrient compositions in three genotypes of eggplants (Solanum melongena ‘African Beauty F1’ and ‘Melina F1’ and S. aethiopicum ‘Kotobi’) grown from seeds irradiated by gamma rays (γ-ray) with 100 Gy. Experiments were carried out in the screenhouse and experimental field of Crop Science Department, University of Calabar, Nigeria. Completely randomised design with four replications and randomised complete block design with three replications was used in the screenhouse and field experiments respectively. Eggplant × γ-ray effect reduced (p ≤ 0.05) seedling emergence, plant height and number of leaves in the nursery at 2 and 4 weeks after sowing. In the field, these traits were consistently lower for irradiated Melina F1 and Kotobi (p &gt; 0.05) at ten weeks after transplanting. Irradiated African Beauty F1 had the highest (p ≤ 0.05) upper canopy leaf area (429.54 cm2), higher (p &gt; 0.05) plant height and stem width; lower (p &gt; 0.05) number of branches and leaves. Un-irradiated and irradiated Kotobi had the highest (p ≤ 0.05) fruit load, lower (p ≤ 0.05) fruit volume, weight and yields over four harvest intervals. Carbohydrate and energy contents of Kotobi fruits grown from 100 Gy gamma-ray irradiated seeds were concurrently improved (p ≤ 0.05). Gamma ray irradiation had both positive and negative influences on the agromorphological traits, mineral composition and nutrient profile of eggplants. However, 100 Gy dose of irradiation had a negative effect on fruit characteristics in general. From the results of this study, inconsistent variations in the agromorphological traits of the irradiated eggplants of the three varieties were reported. Therefore, the goal of mutation breeding in eggplant should not undermine the importance of the eggplant genotype as well as the actual radiation dose.

Effect of Age and Sex on Gene Expression-Based Radiation Biodosimetry Using Mouse Peripheral Blood

Blood-based gene expression profiles that can reconstruct radiation exposure are being developed as a practical approach to radiation biodosimetry. However, age and sex could potentially limit the accuracy of the approach. In this study, we determined the impact of age on the peripheral blood cell gene expression profile of female mice exposed to radiation and identified differences and similarities with a previously obtained transcriptomic signature of male mice. Young (2 months) and old (24 months) female mice were irradiated with 4 Gy X-rays, total RNA was isolated from blood 24 hours later and subjected to whole-genome microarray analysis. Dose reconstruction analyses using a gene signature trained on gene expression data from irradiated young male mice showed accurate reconstruction of 0 or 4 Gy doses with root mean square error of ±0.75 Gy (R2 = 0.90) in young female mice. Although dose reconstruction for irradiated old female mice was less accurate than young female mice, the deviation from the actual radiation dose was not statistically significant. Pathway analysis of differentially expressed genes revealed that after irradiation, apoptosis-related functions were overrepresented, whereas functions related to quantities of various immune cell subtypes were underrepresented, among differentially expressed genes from young female mice, but not older animals. Furthermore, young mice significantly upregulated genes involved in phagocytosis, a process that eliminates apoptotic cells and preserves tissue homeostasis. Both functions were also overrepresented in young, but not old, male mice following 4 Gy X-irradiation. Lastly, functions associated with neutrophil activation that is essential for killing invading pathogens and regulating the inflammatory response were predicted to be uniquely enriched in young but not old female mice. This work supports the concept that peripheral blood gene expression profiles can be identified in mice that accurately predict physical radiation dose exposure irrespective of age and sex.

From corrosion behavior to radiation response: A comprehensive biocompatibility assessment of a CoCrMo medium entropy alloy for utility in orthopedic and dental implants

This paper presents a thorough biocompatibility evaluation of a CoCrMo medium entropy alloy to assess its potential to be utilized in orthopedic and dental implants. For this purpose, a wide range of systematic experiments were carried out, including static immersion, cell culture and radiation experiments. In particular, chemical biocompatibility and ion release behavior of the CoCrMo alloy were studied by carrying out static immersion experiments in artificial saliva (AS), simulated body fluid (SBF) and fetal bovine serum (FBS). Detailed analysis of the surfaces of the tested samples demonstrated that both passive oxide layer and hydroxyapatite formation occur on the CoCrMo sample surfaces immersed in AS, SBF and FBS for 28 days. The response of living cells to the CoCrMo alloy was tested utilizing cell culture experiments, and the evidence of Saos-2 cell viability and proliferation supported the static biocompatibility experiment results, indicating the potential of the CoCrMo alloy to be utilized as an orthopedic implant material. Finally, the effect of a CoCrMo implant on the actual radiation dose induced upon malignant tissue in the vicinity of the implant during a radiotherapy was evaluated by applying medical grade radiation to water phantoms circumventing CoCrMo samples. The results showed that the radiation accumulation in the tissue within the immediate vicinity of a CoCrMo implant would be a minimum, eliminating some of the undesired side effects. Overall, the results of the three different types of experiments reported in this paper have clearly demonstrated that the CoCrMo medium entropy alloy investigated in this study has significant potential to be utilized as a safe implant material in dental and orthopedic implants.

Selective Internal Radiation Therapy with Yttrium-90 for Intrahepatic Cholangiocarcinoma: A Systematic Review on Post-Treatment Dosimetry and Concomitant Chemotherapy.

Selective internal radiation therapy (SIRT) with yttrium-90 (90Y)-loaded microspheres is increasingly used for the treatment of Intrahepatic Cholangiocarcinoma (ICC). Dosimetry verifications post-treatment are required for a valid assessment of any dose-response relationship. We performed a systematic review of the literature to determine how often clinics conducted post-treatment dosimetry verification to measure the actual radiation doses delivered to the tumor and to the normal liver in patients who underwent SIRT for ICC, and also to explore the corresponding dose-response relationship. We also investigated other factors that potentially affect treatment outcomes, including the type of microspheres used and concomitant chemotherapy. Out of the final 47 studies that entered our study, only four papers included post-treatment dosimetry studies after SIRT to quantitatively assess the radiation doses delivered. No study showed that one microsphere type provided a benefit over another, one study demonstrated better imaging-based response rates associated with the use of glass-based TheraSpheres, and two studies found similar toxicity profiles for different types of microspheres. Gemcitabine and cisplatin were the most common chemotherapeutic drugs for concomitant administration with SIRT. Future studies of SIRT for ICC should include dosimetry to optimize treatment planning and post-treatment radiation dosage measurements in order to reliably predict patient responses and liver toxicity.

Evaluation of influencing factors on the radiation dose of hospitalized neonates: Maturity status and type of disease

Context: Premature neonates have multiple medical and surgical problems; therefore, hospitalization and imaging are required. Recently there has been too much concern about the long-term effects of radiation in neonates. In this survey, we assessed the frequency of imaging and radiation dose in neonates hospitalized in neonatal intensive care unit (NICU) in our University-affiliated hospital. Materials and methods: This was a retrospective cross-sectional study conducted during a year (2019–2020) on 291 neonates. The information has been gathered from Health Information System and picture archiving and communication system, and analyzed with SPSS version 22. Results: 291 neonates were included in the study, from which 175 (60%) neonates were preterm and 116 (40%) neonates were term neonates. The mean gestational age (GA) was 35.5 weeks and the mean hospital admission duration was 15.8 days. The mean number of portable and non-portable imaging procedures was 5.13 and 0.62 for preterm and term neonates, respectively. There is a statistically significant relationship between gastrointestinal disease and the number of abdominal X-rays. There is also a statistically significant relationship between acute respiratory distress syndrome (ARDS) and chest X-rays; there is no statistically significant relationship between pneumonia and the number of chest X-rays in the hospital course. The mean accumulation effective doses in preterm and term neonates in-hospital course were 0.549 and 0.498 mSv, respectively. Discussion: The neonates in NICU are more susceptible to radiation hazards due to numerous imaging than other neonates. Portable imaging is eight times more dosing than non-portable imaging, so due to the scattered radiation from portable devices, the actual radiation dose may be higher than what we estimated. No brain CT scan was done for the neonates with convulsion because of using safer and more valuable modalities; so we could recommend radiologists and pediatrics to use substitute modalities like sonography and MRI instead of CT scan and X-rays.

Diagnostic Reference Levels for Fluoroscopy-guided Gastrointestinal Procedures in Japan from the REX-GI Study: A Nationwide Multicentre Prospective Observational Study

SummaryBackgroundDiagnostic reference levels (DRLs) are required to optimize medical exposure. However, data on DRLs for interventional fluoroscopic procedures are lacking, especially in gastroenterology. This study aimed to prospectively collect currently used radiation doses and help establish national DRLs for fluoroscopy-guided gastrointestinal procedures in Japan.MethodsThis multicentre, prospective, observational study collected actual radiation dose data from endoscopic retrograde cholangiopancreatography (ERCP), interventional endoscopic ultrasound (EUS), balloon-assisted enteroscopy (BAE), enteral metallic stent placement, and enteral tube placement from May 2019 to December 2020. The study outcomes were fluoroscopy time (FT: min), air kerma at the patient entrance reference point (Ka,r: mGy), air kerma area product (PKA: Gycm2), and radiation dose rate (RDR: mGy/min). Additionally, the basic settings of fluoroscopy equipment and the factors related to each procedure were investigated. This study was registered in the UMIN Clinical Trial Registry (UMIN 000036525).FindingsOverall, 12959 fluoroscopy-guided gastrointestinal procedures were included from 23 hospitals in Japan. For 11162 ERCPs, the median/third quartile values of Ka,r (mGy), PKA (Gycm2), and FT (min) were 69/145 mGy, 16/32 Gycm2, and 11/20 min, respectively. Similarly, these values were 106/219 mGy, 23/41 Gycm2 and 17/27 min for 374 interventional EUSs; 53/104 mGy, 16/32 Gycm2 and 10/15 min for 523 metallic stents; 56/104 mGy, 28/47 Gycm2, and 12/18 min for 599 tube placements; and 35/81 mGy, 16/43 Gycm2 and 7/15 min for 301 BAEs, respectively. For the overall radiation dose rate, the median/third quartile values of RDR were 5.9/9.4 (mGy/min). The RDR values at each institution varied widely.InterpretationThis study reports the current radiation doses of fluoroscopy-guided gastrointestinal procedures expressed as DRL quantities. This will serve as a valuable reference for national DRL values.FundingThis work was supported by a clinical research grant from the Japanese Society of Gastroenterology.

Awareness level of dentists and dental students about radiation doses of dental imaging methods

Background: To measure the knowledge levels of dentists and dental students about radiation doses of dental imaging techniques. Materials and Methods: A structured questionnaire containing 13 questions was conducted to 251 participants (168 dentists and 83 dental students). The first 6 questions were related to their personal and professional information, and the remaining 7 questions were about the participants’ radiation education and knowledge about radiation doses. Chi-square test was used to determine the relationship between categorical variables, and P < 0.05 was considered statistically significant. Results: The data from 144 (57.4%) women and 107 (42.6%) men were obtained. Gender was not effective on knowledge about radiation doses during dental imaging (p = 0.222). The knowledge of dentists working at the university was statistically higher than those working in the state hospital or private dental offices (p < 0.001). Of the participants, 43.4% (n = 109) stated that the craniofacial mode of cone beam computerized tomography radiates less radiation than the actual dose range, while 32.7% (n = 82) said they had no idea. Conclusion: Most of the dentists and dental students underestimated the actual radiation doses of dental imaging techniques. The dental curriculum should be revised to emphasize radiation protection during imaging. In addition, compulsory vocational postgraduate courses should be organized.

Adaptive modeling of experimental conditions in the processing of food products (chilled fish) by the flow of accelerated electrons

The use of mathematical modeling in various branches of the food industry as an effective tool for the policy of resource conservation of food systems is an innovative solution in the field of improving the efficiency of existing food production technologies based on established patterns in the production process. The issues of operational quality control in the process of processing food products with a stream of accelerated electrons in the absence of radiation doses regulated by standards, except for certain types of spices, to ensure the safety and quality of food products, in particular chilled fish, require a constructive approach with the general predictability of technological parameters in specialized radiation centers – operators of the irradiator. It was found that the dose absorbed by the samples of common carp scales with a high degree of correlation of 0.94 depends on the actual radiation dose and increases to 7.51±0.04 kGy when irradiated with a dose of 12 kGy or 25.9 times compared to samples treated with a stream of accelerated electrons with a radiation dose of 1 kGy. It is revealed that the operational quality is determined by the reproducibility of the results under the established conditions of the production processing process. As a result of experimental testing, mathematical models of various types were developed to predict the absorbed dose from experimental conditions on the example of samples of chilled carp scales: polynomial, 3D-graph and arccos. The practical significance is determined by the possibility of designing experimental conditions for processing chilled fish with a stream of accelerated electrons without performing trial processing of small batches of food products in radiation centers and using emitters as a model for technological runs.

Abstract No. 558 Does lung shunt fraction estimation using injection of 99mTc-MAA still vital in 90Y radioembolization dosimetry? A hypothetical study using patient specific information

To compare and estimate the impact of actual vs. arbitrarily chosen lung shunt fraction (LSF) on 90Y radioembolization dosimetry Institutional review board approved this retrospective study of patients who underwent invasive catheter angiogram with injection of macroaggregated albumin (99mTc-MAA) to measure the actual LSF that was then used in 90Y dosimetry for glass microspheres based radioembolization for hepatocellular carcinoma in 2017 and 2018. 40 patients (mean age, 68 years) underwent 44 injections of 99mTc-MAA. Details related to the targeted liver volume, 99mTc-MAA and 90Y procedures were collected from medical records. Impact of arbitrarily chosen LSF on 90Y dosimetry was compared with the 90Y dosimetry based on actual LSF. There was on average 22 days (range, 10–44) delay between the 99mTc-MAA and 90Y procedures. The mean actual LSF was 4.9% (range, 0.8%–11.3%). Average mass of the treated liver was 0.791 kg (range, 0.3–2.36). The mean prescribed radiation dose was 153.7 Gy (range, 110– 320 Gy). The actual radiation dose deposited by glass microspheres was estimated to be 153.4 Gy (range, 100.6–318.4). Alternatively, if 90Y dosimetry is calculated using an arbitrarily chosen LSF of 5%, a minimum commercially available radioactivity (i.e., 3 GBq at the time of calibration) required for the smallest treatment mass (0.3 kg) in this study group would deposit a dose of 118 Gy at 4 pm on a Friday, and the maximum commercially available radioactivity (20 GBq) for the largest treatment mass (2.36 kg) would deposit a dose of 321 Gy at 8 am on a Monday. This study indicates the feasibility of using arbitrary LSF in 90Y dosimetry. When a range of commercially available vials of radioactivity is readily available at the treatment enter, glass microspheres based radioembolization using arbitrarily chosen LSF based 90Y dosimetry would be feasible without the need for 99mTc-MAA injection in most patients. However, an alternative method to predict and identify the small percentage of patients who could have high LSF is required to prevent significant pulmonary injury from radioembolization based on arbitrarily chosen low LSF.

35 лет после аварии на Чернобыльской АЭС: методы ретроспективной дозиметрии в оценке последствий крупномасштабных неконтролируемых радиационных воздействий, их последующее развитие и применение в онкорадиологии (опыт МРНЦ им. А.Ф. Цыба)

Individual retrospective dosimetry was developed at A. Tsyb Medical Radiological Research Centre (A. Tsyb MRRC) after the Chernobyl accident for assessment and analysis of radiation effects on people lived in radioactively contaminated settlements in the Kaluga and Bryansk regions. The method was also used in radiation epidemiology case-control studies within frames of international pilot projects. The ob-tained data demonstrated reliable dose-response relationship for thyroid cancer in patients with diag-nosed thyroid cancer, who were children and adolescents at the time of the accident and resided in radi-oactively contaminated areas in the Bryansk region. The dose-response relationship for diagnosed inva-sive breast cancer was found in women, resided in radioactively contaminated settlements since the acci-dent till the first diagnosis of cancer that was established within the period from October 2008 to February 2013. Their age at diagnosis was under 55 years. At the same time, no dose-response relationship for leu-kaemia was found in children under 5 years old at the time of the accident. The individual retrospective dosimetry method has been updated and used in pilot studies for verifying conservative estimates of radi-ation doses to the population exposed to radiation as a result of nuclear tests at the Semipalatinsk nuclear test site, as well as for verifying estimates of external radiation doses to people affected by the accident at the Fukushima Daiichi NPP. The method was also used for estimating individual doses from residual radi-oactivity for the survivors of the Hiroshima and Nagasaki atomic bombings. The long-term collaboration continues under bilateral International Collaboration Agreements between the National Medical Research Radiological Centre and leading research centres in the Republic of Kazakhstan and Japan. Since 2016 researchers and physicians of A. Tsyb MRRC have modi-fied method of stimulated luminescence of natural and synthetic materials and developed innovative technology in vivo dosimetry that has been put into clinical practice for estimating spatial radiation doses distribution in internal organs at risk during the brachytherapy of prostate cancer, gynecologic and recur-rent pelvic tumors, as well as for estimating local radiation dose to the skin of the breast gland with the tumor. The 35-year experience in the development and application of methods for individual retrospective dosimetry after the Chernobyl accident formed the basis for identifying future-pointing trends for the de-velopment of novel applications of stimulated luminescence techniques. Radiation-induced stimulated luminescence dosimetry can be applicable in uncontrolled radiation events; retrospective dosimetry method applicable for neutron beam radiation therapy is under development. The method of in vivo do-simetry is useful in radiation oncology. Now assembled thermoluminiscent micro-sized dosimeters are used for arterial radioembolization. At present, feasibility of using items of clothing and special inserts (buttons, fastenings, etc.), parts of wearable electronic devices as natural dosimeters, as well as the feasi-bility of using luminescent microdosimeters, made of different materials, after exposure to high LET radiation ranged from a fraction of mGy to the dose greater than 60 Gy have been examined. Development of flexible planar microdosimeter assemblies in order to obtain more detailed information about possible discrepancy in distribution of planned and actual radia-tion doses to patients during radiotherapy is considered.

On the Need of In Vivo Dosimetry as Quality Control for Intraoperative Electron Radiotherapy in Breast Cancer

Intraoperative electron radiotherapy (IOERT) is a highly selective radiotherapy technique to treat limited anatomic volumes during oncological surgery. Although the applicator and protecting shield placement are closely correlated with two risks: PTV underdosage and OAR irradiation. In vivo film dosimetry has proven to be an effective methodology to evaluate the actual radiation dose delivered to the target as well as to verify correct alignment between the applicator and the disk. The aim of our study is to report and analyze the causes of the misalignment between applicator and the disk using radiochromic films during IOERT. From November 2019 to nowadays in vivo dosimetry was performed for 10 patients with breast cancer who underwent IOERT. To perform in vivo film dosimetry several radiochromic film templates were created according to the different diameters of the shielding disc. They were sterilized by hydrogen peroxide plasma and then sutured on the outer face of the protective disc. IOERT was performed using a LIAC accelerator. The size of the collimator device was based on the tumor size. The PTV was a 3D volume of 1–2 cm beyond the edge of the anterior macroscopic tumor. After removal of the tumor, the steel disc, 1 cm wider than the applicator, was placed between the treatment volume and the chest wall to protect the OAR. The steel disk was sutured to the pectoral muscle to avoid undesired movement during the following steps. The tissue surrounding the excision cavity was temporarily sutured within the area defined by the PTV to ensure complete irradiation of the tumor bed margins. The energy was chosen according to the depth of the tumor bed. After the irradiation, the radiochromic film was removed and scanned. The percentage of the irradiation circle outside the disk was recorded and parameters such applicator angulations, prescription depth, tumor location and breast size were analyzed. The correlation was analyzed using the linear coefficient of determination. The postprocessing analysis of the dose distribution measured on the films provides a quantitative estimate of the misalignment between the collimator and the disk. For the 10 analyzed patients. The average surface outside the protective disc is 15% of the irradiated area (range 3% to 32%) corresponding to an average surface of 3cm2 (range 0.7 to 6.4 cm2). No relationship was found between the quadrant of the irradiated breast tissue and the percentage of irradiation outside the field. There was no correlation either between the size of the breast cup, the angulations of the accelerator or the energy used. Our preliminary results show misalignment between the applicator and the shielding disk during IOERT similar to the literature reports. None of the analyzed parameters correlate to the amount of misalignment. In- vivo dosimetry should be used as a quality check during IOERT process and future methods to improve the procedure should be tested

The effect of sunlight and UV lamp exposure on EPR signals in X-ray irradiated touch screens of mobile phones

Electron paramagnetic resonance (EPR) signals generated by ionizing radiation in touch-screen glasses have been reported as useful for personal dosimetry in people accidently exposed to ionizing radiation. This article describes the effect of light exposure on EPR spectra of various glasses obtained from mobile phones. This effect can lead to significant inaccuracy of the radiation doses reconstructed by EPR. The EPR signals from samples unexposed and exposed to X-rays and/or to natural and artificial light were numerically separated into three model spectra: those due to background (BG), radiation-induced signal (RIS), and light-induced signal (LIS). Although prolonged exposures of mobile phones to UV light are rather implausible, the article indicates errors underestimating the actual radiation doses in dose reconstruction in glasses exposed to UV light even for low fluences equivalent to several minutes of sunshine, if one neglects the effects of light in applied dosimetric procedures. About 5 min of exposure to sunlight or to light from common UV lamps reduced the intensity of the dosimetric spectral components by 20–60% as compared to non-illuminated samples. This effect strongly limits the achievable accuracy of retrospective dosimetry using EPR in glasses from mobile phones, unless their exposure to light containing a UV component can be excluded or the light-induced reduction in intensity of the RIS can be quantitatively estimated. A method for determination of a correction factor accounting for the perturbing light effects is proposed on basis of the determined relation between the dosimetric signal and intensity of the light-induced signal.

Optimal cumulative dose of cisplatin for concurrent chemoradiotherapy among patients with non-metastatic nasopharyngeal carcinoma: a multicenter analysis in Thailand

BackgroundChemoradiotherapy (CRT) with high cumulative doses (CDs) of cisplatin has been considered the standard of care for non-metastatic nasopharyngeal carcinoma (NPC). However, given most patients’ inability to tolerate high CDs due to cisplatin-related toxicities, the optimal CD of cisplatin during CRT remains undetermined.MethodsPatients with non-metastatic NPC who received CRT with cisplatin between 2007 and 2017 were identified through the Thai head and neck cancer multicenter database and then categorized according to cisplatin CD (mg/m2) received. All complications and cisplatin-related toxicities during CRT were recorded.ResultsWe identified 779 non-metastatic NPC patients receiving low (≤150; n = 97), intermediate (151–250; n = 411), and high (> 250; n = 271) CDs of cisplatin. Low CD patients had significantly lower mean actual radiation dose (p < 0.001) and more radiotherapy delay (p = 0.010), while intermediate CD patients had the least hospitalization (p < 0.001). Overall, 39.3% of the patients experienced cisplatin-related toxicity, which was associated with poor overall survival (OS) (p = 0.001). Acute kidney injury was observed in 7% in all patients, which was highest among low CD patients (15.5%; p = 0.002). Intermediate CD patients had significantly longer median OS than the low and high groups (64 vs. 49.8 vs. 53.2, respectively; p = 0.015). Univariate, but not multivariate, analysis showed that CD of cisplatin was significantly associated with OS.ConclusionCD of cisplatin during CRT was not an independent prognostic factor for OS. An intermediate CD induced minimal toxicity without compromising survival and should be considered the optimal CD. Nonetheless, a randomized phase 3 study evaluating the optimal CD of cisplatin is warranted.

Calculation of Size-Specific Dose Estimation (SSDE) of The Pediatric’s Head for Tube Current Modulation (TCM) CT Examinations

Computed Tomography (CT) examinations in the pediatric patient are sensitive to the impact of ionizing radiation, which gives long-term risk. In addition, the actual radiation dose delivered during CT examinations has not been well-described mainly when using tube current modulation (TCM) technique. To quantified this effect, an algorithm for calculating radiation dose is needed. Therefore, this study aims to calculate and analyze the estimated effective dose of head examinations from 3D CT images, based on the equivalent water diameter (Dw)For the TCM technique. Four pediatric patients in the 0-6-year-old age groups were examinations using Somatom Definition Flash with variation in the number of slices. CTDIvol and Tube current values were obtained from the DICOM header. There are two main parts algorithm for Dw calculation. First, images of CT data were converted to Hounsfield units (HU). Then, Dw values based on the patients contour using the K-mean cluster and morphological gradient algorithm were calculated for every slice. The coefficient factor is obtained by American Association of Physicists in Medicine (AAPM) report 220. The values then multiplied by CTDIvolto acquire values of SSDE. The results showed that the relation between SSDE and tube current was strongly correlated with R2 values of 0.982.

Usefulness of Silicon Bolus Using 3D Printing of Head and Neck Patients

Radiation therapy of oral and head and neck cancers often involves skin in the therapeutic range, and the use of bolus is frequently used. Dose irregularities provide dose uncertainty in patient application. In this study, the physical properties of patients with gel bolus, poly lactic acid (PLA), and silicon using 3D printing were fabricated. Dose uncertainties arising from the actual radiation dose delivery were measured. As a result, PLA bolus was stable in the Common irregularities. Silicon bolus may be useful for patients with severe irregularities or frequent changes in patient's body shape.

Application of 640-slice CT wide-detector volume scan in low-dose CT pulmonary angiography.

Computed tomography (CT) pulmonary angiography (CTPA) examination has been frequently applied in detecting suspected pulmonary embolism (PE). How to reduce radiation dose to patients is also of concern. To assess the value of using 640-slice CT wide-detector volume scan with adaptive statistical iterative reconstruction (ASIR) algorithm in low-dose CTPA. Fifty-eight patients who performed with CTPA were divided into two groups randomly. In the first experimental group (n = 30), ASIR combined with volume scan were performed on the patients, while in the second conventional group (n = 28), patients received ASIR combined with conventional spiral scan. General data including age and body mass index, image quality, pulmonary arterial phase, and radiation dose were analyzed by t test in the two groups. In both groups, all images revealed the 5-order or higher pulmonary arterial branches and fully met the needs for clinical diagnosis. There was no statistical difference in general data between the two groups. In terms of pulmonary phase accuracy, compared with the conventional group, images at pulmonary arterial phase could be captured more accurately in the experimental group. CTDI in the experimental group decreased by 30% compared with that in the conventional group. The actual radiation dose in the experimental group was 1.5 mSv, which is reduced by 53% compared to that in the conventional group. Compared with the conventional spiral scan, using 640-slice CT volume scan with ASIR in CTPA is more accurate in scanning phase and has lower radiation dose. There is no significant difference in image quality between the two groups.

Radiation doses in diagnostic imaging for suspected physical abuse

ObjectiveTo measure the actual radiation dose delivered by imaging techniques commonly used in the radiography of suspected physical abuse and to make this information available to health professionals and families.MethodsData...