Measurement of scattered rays from different materials using an inorganic scintillator based optical fiber sensor and its application in radiotherapy

Measurements using an Optical Fiber OFS including an inorganic scintillator placed on the surface of a phantom show that the particle energy distribution inside the phantom remains unchanged. The backscattered intensity measured using an Optical Fiber Sensor (OFS) exhibits a linear relationship with the total radiation dose delivered to the phantom, and this relationship shows that the OFS can be used for indirect dose measurement when located on the surface of the phantom i.e. that arising from the energetic backscattered electrons and photons. Such a device can therefore be used as a clinical in-vivo dosimeter, being located on the patient’s body surface. In addition, the measurement results for the same OFS located inside and outside the radiation field of a compound water based phantom are analyzed. The differences in measurement of the fluorescence signal in response to various tissue materials representing bone or tumor tissue in the irradiation field are strongly related to the material's ability to block the scattered rays from the water phantom, as well as the scattered X-rays generated by the material located within the phantom.

New Possibilities of Refractive Modeling of the Cornea by the Radiation of an Argon-fluorine Excimer Laser

Purpose: To consider new possibilities of refractive modeling of the cornea by the radiation of an argon-fluorine excimer laser in ablative and subablative modes after saturation of the stroma with riboflavin. Materials and Methods: Experimental (20 pork, 90 rabbit eyes) and clinical studies on photorefractive and phototherapeutic operations with saturation of the corneal stroma with riboflavin (610 operations) were analyzed. To activate riboflavin, secondary radiation induced by exposure to ablative and subablative energy densities was used. A quick transition to energy densities below the ablation threshold without additional calibrations was carried out using a “Microscan Visum-500” excimer laser (Optosystems, Russia). An objective assessment of the refractive keratomodelling effect and visual results was carried out according to the data of complex optometric studies. Results: Experimental and clinical studies have shown the advantages of refractive keratomodeling by theradiation of an argon-fluorine excimer laser in ablative and subablative modes after saturation of the stroma with riboflavin. Isotonic 0.25% riboflavin solution did not affect the accuracy of refractive ablation and blocked the negative effect of induced secondary radiation on keratocytes and corneal nerves. This reduced the aseptic inflammatory response and the risk of developing an irreversible form of fibroplasia. Ablation with riboflavin initiated a damped crosslinking effect, which increased the photoprotective and strength properties of the thinned cornea. A refractive keratomodelling effect was found when energy densities were applied below the stromal ablation threshold. The magnitude of this refractive effect depended on the total radiation dose and the topography of the affected area. This approach made it possible to implement laser-induced refractive keratomodeling without ablation of the corneal stroma. Conclusion: Refractive modeling of the cornea by the radiation of an argon-fluorine excimer laser in ablative and subablative modes after saturation of the stroma with riboflavin opens up new possibilities in laser correction of ametropia.

The Influence of Mesenteric Defects Closure on the Use of Computed Tomography for Abdominal Pain 5 Years After Laparoscopic Gastric Bypass—a Post Hoc Analysis of a Randomized Clinical Trial

Background Abdominal pain after laparoscopic Roux-en-Y gastric bypass (LRYGB) is a common and unwanted complication that typically leads to further exploration through radiology. Concerns have been raised regarding the consequences of this radiation exposure and its correlation with the lifetime risk of cancer. The aim of this study was to evaluate the differences in computed tomography (CT) use between LRYGB patients with open and closed mesenteric defects and to assess the radiological findings and radiation doses. Methods This subgroup analysis included 300 patients randomized to either closure (n = 150) or nonclosure (n = 150) of mesenteric defects during LRYGB. The total number of CT scans performed due to abdominal pain in the first 5 postoperative years was recorded together with the radiological findings and radiation doses. Results A total of 132 patients (44%) underwent 281 abdominal CT scans, including 133 scans for 67 patients with open mesenteric defects (45%) and 148 scans for 65 patients with closed mesenteric defects (43%). Radiological findings consistent with small bowel obstruction or internal hernia were found in 31 (23%) of the scans for patients with open defects and in 18 (12%) of the scans for patients with closed defects (p = 0.014). The other pathological and radiological findings were infrequent and not significantly different between groups. At the 5-year follow-up, the total radiation dose was 82,400 mGy cm in the nonclosure group and 85,800 mGy cm in the closure group. Conclusion Closure of mesenteric defects did not influence the use of CT to assess abdominal pain. Graphical abstract

Incidence of dry eye after radiotherapy for head and neck tumours: a tertiary Care Hospital North West Rajasthan

Background: Radiotherapy plays a critical role in the management of many patients with head-and-neck (H&N) cancer. To study the incidence of dry eye associated with radiotherapy and correlate them with dose of radiation.Methods: This Hospital based prospective study comprises of 100 patients of head and neck tumors who received radiotherapy by linear accelerator from 2015 to 2017. Ocular examination was done prior to the start of therapy, 1st follow up at 15th day of therapy, 2nd at last day of therapy (23-35 fraction), 3rd at 3 months after completion of therapy for side effects, 4th at 6 months, 5th at 12 month and 6th at 18 months after completion of therapy for assessing dry eye.Results: 59% patients developed dry eye. 44 patients received dose 45-55 Gy and out from these 13 (29.50%) patients developed dry eye, 40 patients received dose 56-65 Gy and out from these 33 (78.00%) patients developed dry eye and 16 patients received dose 66-70 Gy and out from these 13 (95.00%) patients developed dry eye.Conclusions: We concluded that the incidence of dry eye increased with increased total radiation dose. The current study suggests the importance of total dose as well as dose per fraction despite advancement of radiotherapy techniques and using protective mechanisms for eye complications developed.

Characteristics of endoprosthesis replacement of bones and joints in patients with metastatic lesions

The article presents the results of endoprosthesis replacement of joints and bones in 19 patients with bone metastasis. The complications resulted from endoprosthesis replacement of joints and bones in cases of bone metastasis were observed in 4 (21.1 %) patients, and tumor recurrences were observed in 2 (10.5 %) patients. In the preoperative period, 19 patients underwent courses of external beam radiotherapy with a total radiation dose (TRD) of 40 Gray, with a single mediated dose (SMD) of 2–2.5 Gray. Also, all patients received preoperative multiagent chemotherapy treatment cycles depending on the primary source of the tumor, and in cases of hormone-dependent tumors, the patients received hormone therapy. Depending on the specific anatomical and functional changes, special implant designs, tools, and techniques were used, which complemented the standard technique of operations. The basic principles of oncosurgery have been adhered to during endoprosthesis replacement of joints and bones, i.e. standard principles of resection and ablastics, removing en bloc of a biopsy area. In endoprosthesis replacement, a cement type of endoprosthesis fixation was used. For an adequate formation of the muscle envelope of the endoprosthesis, a plastic stage of the ope-ration was performed, which allowed to adequately cover the installed endoprosthesis, and thus, reduce the risk of infectious complications. Both displaced and free vascularized musculocutaneous flaps on microvascular anastomoses were used as plastic material. To limit the contact of the metal part of the endoprosthesis with the surrounding tissues and to reconstruct the tendon ligamentous apparatus, a tube of polyethylene tetraphthalate was used, resected tendon and muscles were sutured to it, which allowed to more fully restore joint action. The functioning of extremity according to the MSTS scale after endoprosthesis replacement of joints ranged from 70 to 92 %, and also the quality of life of patients improved up to 70–75 points.

The Lymph-Sparing Quotient: A Retrospective Risk Analysis on Extremity Radiation for Soft Tissue Sarcoma Treatment

Radiation therapy (RT) for extremity soft tissue sarcoma is associated with lymphedema risk. In this study, we analyzed the influence of lymph-sparing volume on the lymphedema occurrence in patients who received adjuvant extremity RT. The lymph-sparing quotient (LSQ) was calculated by dividing the lymph-sparing volume by the total extremity volume with double weightingfor the narrowest lymph-sparing region. A total of 34 patients were enrolled in this analysis. The median applied total radiation dose was 66.3 Gy in 36 fractions. Acute lymphedema appeared in 12 patients (35%). Most of them (n = 8) were lymphedema grade 1 and five patients had grade 2 to 3 lymphedema. Chronic lymphedema appeared in 22 patients (65%). 17 of these patients had at least a grade 2 lymphedema. In 13 of 14 patients with an LSQ ≤ 0.2 and 11 of 20 patients with an LSQ > 0.2, an acute or chronic lymphedema ≥ grade 2 was observed. A Kaplan–Meier Analysis of the two groups with the endpoint of a two-year lymph edema-free survival (=2-YLEFS) was estimated with an univariate, significant result (2-YLEFS LSQ ≤ 0.2 vs. LSQ > 0.2: 0% vs. 39%; p = 0.006; hazard ratio LSQ ≤ 0.2 vs. > 0.2 2-YLEFS 2.822 (p = 0.013); 95% confidence interval (CI): 1.24–6.42). Maximizing the potential oncologically-justifiable lymph-sparing volume should be considered to reduce the risk of high-grade lymphedema when applying RT to extremities.

First experience of efficacy and radiation exposure in 320-detector row CT fluoroscopy-guided interventions

Objective: We investigated the efficacy and exposure to radiation in 320-detector row computed tomography fluoroscopy-guided (CTF-guided) interventions. Methods: We analysed 231 320-detector row CTF-guided interventions (207 patients over 2 years and 6 months) in terms of technical success rates, clinical success rates, complications, scanner settings, overall radiation doses (dose–length product, mGy*cm), patient doses of peri-interventional CT series, and interventional CT (including CTF), as a retrospective cohort study. The relationships between patient radiation dose and interventional factors were assessed using multivariate analysis. Results: Overall technical success rate was 98.7% (228/231). The technical success rates of biopsies, drainages, and aspirations were 98.7% (154/156), 98.5% (66/67), and 100% (8/8), respectively. The clinical success rate of biopsies was 93.5% (146/156). All three major complications occurred in chest biopsies. The median total radiation dose was 522.4 (393.4–819.8) mGy*cm. Of the total radiation dose, 87% was applied during the pre- and post-interventional CT series. Post-interventional CT accounted for 24.4% of the total radiation dose. Only 11.4% of the dose was applied by CTF-guided intervention. Multilinear regression demonstrated that male sex, body mass index, drainage, intervention time, and helical scan as post-interventional CT were significantly associated with higher dose. Conclusion: The 320-detector row CTF interventions achieved a high success rate. Dose reduction in post-interventional CT provides patient dose reduction without decreasing the technical success rates. Advances in knowledge: This is the first study on the relationship between various interventional outcomes and patient exposure to radiation in 320-detector row CTF-guided interventions, suggesting a new perspective on dose reduction.

Necrosis of the optic nerve and chiasm with safe radiation doses: Report of two rare cases

Introduction: Radiation-induced optic neuropathy (RION) is still a devastating complication of brain and skull base radiation that has no effective treatment up until today, thus uttermost caution must be taken in treating patients that brain radiotherapy is needed. We present two cases of RION that happened in seemingly safe radiation doses. Case description: A 48-year-old female with a history of pleomorphic pituitary adenoma developed bilateral and painless loss of vision 10 months after radiation to the brain; the total radiation dose was 45 Gy in 25 fractions and no other risk factors of RION were found. Magnetic resonance imaging of the brain depicted bilateral prechiasmatic optic nerve enhancement with involvement of the optic chiasm. Treatment with high doses of corticosteroids was unsuccessful. A 62-year-old female with a history of lung adenocarcinoma and brain metastases presented with a 1-month history of decreased vision in both eyes. He had undergone whole-brain radiotherapy with a total dose of 30 Gy over 10 fractions and concurrent chemotherapy with cisplatin and pemetrexed. Brain magnetic resonance imaging (MRI) with contrast showed bilateral intracranial optic nerve enhancement. Conclusions: This is the second case report of RION in a patient with a history of brain radiotherapy and concurrent chemotherapy with pemetrexed. History of chiasmal compression, concurrent use of chemotherapeutic agents, and high fraction size (despite the safety of total radiation dose) were possible contributing risk factors to develop RION in our cases. Hence, adjusting the radiation dose according to the presence of these risk factors is recommended.

Using Geiger Dosimetry EKO-C Device to Detect Ionizing Radiation Emissions from Building Materials

The purpose of the article is to check and assess what radiation is emitted by particular building materials with the passage of time. The analysis was performed with the EKO-C dosimetry device from Polon-Ekolab. The scope of the work included research on sixteen selected construction materials, divided into five groups. The analysis of the results showed that samples such as bricks (first group) and hollow blocks (second group) emit the highest radiation in the tested objects. When comparing these materials, the highest value was recorded when measuring the ceramic block of 15.76 mSv·yr−1. Taking into account the bricks, the highest value of radiation was shown by a full clinker brick, 11.3 mSv·yr−1. Insulation materials and finishing boards are two other groups of building materials that have been measured. They are characterised by a low level of radiation. In the case of materials for thermal insulation, the highest condition was demonstrated by graphite polystyrene of 4.463 mSv·yr−1, while among finishing boards, the highest value of radiation was recorded for the measurement of gypsum board of 3.76 mSv·yr−1. Comparing the obtained test results to the requirements of the Regulation of the Council of Ministers on ionizing radiation dose limits applicable in Poland, it can be noted that the samples examined individually do not pose a radiation risk to humans. When working with all types of samples, the radiation doses are added up. According to the guidelines of the regulation, the total radiation dose does not exceed 50 mSv·yr−1 and does not constitute a threat to human health.

SOME ISSUES OF LIFE ACTIVITIES OF POPULATION IN THE CHORNOBYL EXCLUSION ZONE IN UKRAINE

Background. Radiation accidents at the Chornobyl Nuclear Power Plant (USSR, 1986) and Fukushima-1 (Japan, 2011) have shown that global environmental contamination is an intervention in normal human life making negative effect on population health. These accidents highlighted a number of statutory and regulatory both with medical and social problems for individuals, who returned voluntarily for permanent residence in the Chornobyl Exclusion Zone i.e. a radiation-hazardous area (they are named the «self-settlers»). Objective: generalization of experience in the settlement of normative-legal, ecological-dosimetric and medicosocial life issues of population living in the Chornobyl NPP (ChNPP) Exclusion Zone («self-settlers»). Object and methods. The chosen problem is complex, necessitating the generalization of radiation-hygienic, medical-biological, socio-economic, demographic and sociological research results obtained by the national and foreign authors. A set of theoretical research and analysis of empirical data methods on the principles of interdisciplinary interaction was used; the systematic, legal, economic, medical-biological, demographic and retrospective-dosimetric approaches of research were applied. Results. It was shown that a part of population refused to evacuate or had returned for permanent residence to the radiation-hazardous lands after the ChNPP accident. In 1986–2009 the number of «self-settlers» ranged from 150 to 2,000 in different years. In 2021 – the 101 people. Those were mainly people of working age, mostly females, single people or widows/widowers. Рrevious medical and dosimetric studies have shown that long-term residence in the Exclusion Zone affects physical and mental health of «self-settlers» and causes atypical aging, including involvement of the central nervous system. According to calculations, the average effective total radiation dose accumulated by «self-settlers» for the first 3 years was 30 % of dose for the entire post-accident period, and the dose accumulated over 20 years was 54 % of the dose accumulated over 35 years. But the effective radiation doses accumulated in different periods after the accident differ significantly in residents of different Exclusion Zone settlements. This information needs further study in terms of the «radiation dose - health status» dependence. Conclusions. The effective radiation doses accumulated in different periods after the accident differ significantly in the residents of different Exclusion Zone settlements. Тhe average effective total radiation dose accumulated by «self-settlers» for the first 3 years was 30 % of the dose for the entire post-accident period, and the dose accumulated over 20 years was 54 % of the dose accumulated over 35 years. The Scientific Council meeting of NAMS approved the NRCRM Annual Report. Key words: Chornobyl Nuclear Power Plant, Exclusion Zone, «self-settlers», radiation doses, health.