Total Cumulative Radiation Dose Research Articles

Effects of genome instability under irradiation in different CT scanning modes. Results of ex vivo pilot cohort study

Introduction. Medical radiation is one of the leading sources of public exposure in the world. In recent decades, the total number of X-ray diagnostic procedures has increased significantly, and with the increase in the volume of computed tomography (CT), a significant gain in the total cumulative radiation dose is also associated. 
 The aim of the work is to compare the genotoxic effects of irradiation of human blood lymphocytes using various CT protocols. 
 Materials and methods. Among patients of different genders and ages who sought for a preventive examination, nine practically healthy volunteers (donors) who signed an informed consent, were randomly selected to participate in the ex vivo experiment. 4 venous blood samples from each donor were irradiated on various CT protocols (0.82–11.8 mSv) in an anthropometric phantom of the human chest. Aliquots of each sample were cultured under conditions of cytokinesis block, recorded and analyzed according to the protocol of cytomic analysis in a micronucleus test.
 Results. Irradiation of blood samples in the Ultra-NDCT mode (0.82 mSv) revealed a peak in the proliferation of rapidly dividing cells and the frequency of genetic damage in them, and also demonstrated a high probability of the formation and consolidation of genetic damage in generations of dividing cells. This indicates increased genotoxicity and, most likely, immunotropicity of the studied irradiation mode.
 Llimitation of the study is the inadmissibility of involving a person in an experiment or using biomaterials without obtaining his consent, as well as the inadmissibility of causing physical harm or harm to human honor and dignity during the experiment
 Conclusion. When choosing CT modes, it is necessary to take into account not only the levels of effective doses, but also the possibility of developing the effects 
 of genome instability. However, this approach requires additional genotoxic studies of CT protocols in the range from <1 to 100 mSv.

Design and Validation of a V-Gate n-MOSFET-Based RH CMOS Logic Circuit with Tolerance to the TID Effect

This study designed a radiation-hardened (RH) complementary metal oxide semiconductor (CMOS) logic circuit based on an RH variable-gate (V-gate) n-MOSFET that was resistant to the total ionizing dose (TID) effect and evaluated its tolerance to radiation. Among the different CMOS logic circuits, NOT, NAND, and NOR gates were designed using V-gate n-MOSFETs by employing layout transformation techniques and standard p-MOSFETs. Before the process design, we predicted the radiation damage using modeling and simulation techniques and validated the tolerance by conducting actual radiation tests after the process design. Furthermore, we implemented the CMOS logic circuit process design in a 0.18 µm CMOS bulk process. The actual radiation test applied a total cumulative radiation dose of 25 kGy at 5 kGy per hour in a high-level gamma-ray irradiation facility. Consequently, the resistance of the RH CMOS logic circuit based on the RH V-gate n-MOSFET to the TID effect was validated through experiments.

Effects of Gamma Radiation on Resonant and Antiresonant Characteristics of Piezoelectric Wafer Active Sensors

This paper presents gamma radiation effects on resonant and antiresonant characteristics of piezoelectric wafer active sensors (PWAS) for structural health monitoring (SHM) applications to nuclear-spent fuel storage facilities. The irradiation test was done in a Co-60 gamma irradiator. Lead zirconate titanate (PZT) and Gallium Orthophosphate (GaPO4) PWAS transducers were exposed to 225 kGy gamma radiation dose. First, 2 kGy of total radiation dose was achieved with slower radiation rate at 0.1 kGy/h for 20; h then the remaining radiation dose was achieved with accelerated radiation rate at 1.233 kGy/h for 192 h. The total cumulative radiation dose of 225 kGy is equivalent to 256 years of operation in nuclear-spent fuel storage facilities. Electro-mechanical impedance and admittance (EMIA) signatures were measured after each gamma radiation exposure. Radiation-dependent logarithmic sensitivity of PZT-PWAS in-plane and thickness modes resonance frequency (∂(fR)/∂( logeRd)) was estimated as 0.244 kHz and 7.44 kHz, respectively; the logarithmic sensitivity of GaPO4-PWAS in-plane and thickness modes resonance frequency was estimated as 0.0629 kHz and 2.454 kHz, respectively. Therefore, GaPO4-PWAS EMIA spectra show more gamma radiation endurance than PZT-PWAS. Scanning electron microscope (SEM) and X-ray diffraction method (XRD) was used to investigate the microstructure and crystal structure of PWAS transducers. From SEM and XRD results, it can be inferred that there is no significant variation in the morphology, the crystal structure, and grain size before and after the irradiation exposure.

Treatment-Related Radiation Toxicity Among Cervical Cancer Patients.

The purpose of this study is to identify incidence of and factors associated with severe late toxicity in women treated with radiation for cervical cancer. All patients with cervical cancer treated with radiation as primary or adjuvant therapy from 2005 to 2017 in a single academic institution were included. Records were reviewed for demographic information, Charlson Comorbidity Index, treatment details, toxicities, and outcomes. Patients with and those without severe late gastrointestinal toxicity (SLGIT), severe late genitourinary toxicity (SLGUT), or any SLGIT or SLGUT, defined as any toxicity (AT), were compared. Overall survival and progression-free survival were also compared. Of 179 patients identified, 21.2% had AT, 17.3% had SLGIT, and 10% had SLGUT. Estimated AT rate at 3 years was 24.2%. The mean duration of follow-up was 37 months (range, 3-146 months). Most patients (84.1%) received 3-dimensional conformal therapy, and 15.9% received intensity-modulated radiation therapy. Factors associated with AT were lower body mass index (24.9 vs 28.3, P = 0.043), white race (63.2% vs 44%, P = 0.035), and active tobacco smoking during treatment (59.5% vs 40.2%, P = 0.036). Any toxicity was not associated with 3-dimensional versus intensity-modulated radiation therapy planning, low-dose versus high-dose-rate brachytherapy or time to complete radiation treatment. Higher total cumulative radiation dose to clinical target volume was associated with SLGIT. Progression-free survival and overall survival were similar among patients with AT compared to those without toxicity. In patients with cervical cancer, radiation toxicity is correlated with lower body mass index, white race, and smoking. Despite technologic advances in radiotherapy planning and delivery, toxicity remains high and interventions to reduce the burden of treatment are needed.

Incidence of cancer among licenced commercial pilots flying North Atlantic routes

BackgroundTo evaluate cancer incidence among licenced commercial pilots in association with cosmic radiation.MethodsCohort study where ionizing radiation dose of cosmic radiation was estimated from airline data and software program and cancer incidence was obtained by record linkage with nation-wide cancer registry. All licenced commercial male airline pilots were followed from 1955 to 2015, ever or never employed at airline with international routes. Standardized incidence ratios were calculated and relative risk by Poisson regression, to examine exposure-response relation.ResultsEighty three cancers were registered compared with 92 expected; standardized incidence ratios were 0.90 (95% CI 0.71 to 1.11) for all cancers, 3.31 (95% CI 1.33 to 6.81) for malignant melanoma, and 2.49 (95% CI 1.69 to 3.54), for basal cell carcinoma of skin. The risk for all cancers, malignant melanoma, prostate cancer, basal cell carcinoma of skin, and basal cell carcinoma of trunk increased with an increase in number of employment years, cumulative air hours, total cumulative radiation dose, and cumulative radiation dose sustained up to age of 40 years. The relative risk for the highest exposure categories of cumulative radiation dose were 2.42 (95% CI 1.50 to 3.92) for all cancers, 2.57 (95% CI 1.18 to 5.56) for prostate cancer, 9.88 (95% CI 1.57 to 190.78) for malignant melanoma, 3.61 (95% CI 1.64 to 8.48) for all basal cell carcinoma, and 6.65 (95% CI 1.61 to 44.64) for basal cell carcinoma of trunk.ConclusionsThis study was underpowered to study brain cancer and leukaemia risk. Basal cell carcinoma of skin is radiation-related cancer, and may be attributed to cosmic radiation. Further studies are needed to clarify the risk of cancers in association with cosmic radiation, other workplace exposure, host factors, and leisure sun-exposure, as clothes, and glass in cockpit windows shield pilots from the most potent ultraviolet-radiation.

Second cancer risk after diagnostic and monitoring radiation exposure with computed tomography in patients with hepatocellular carcinoma.

238 Background: Contrast-enhanced dynamic computed tomography (CT) is preferred for initial diagnosis and post-treatment monitoring of hepatocellular carcinoma (HCC). The risk of a second cancer with diagnostic and monitoring CT radiation exposure in HCC patients is unclear. Methods: We analyzed cumulative radiation dose (CRD) for diagnostic and monitoring CT with/without transarterial chemoembolization (TACE) in patients with HCC alone (HA group) and HCC patients with a second cancer (SC group), using the big dataset of the National Health Insurance of South Korea. We performed survival analysis, with death treated as a competing risk. Results: A total of 20,073 patients with HCC were enrolled. With a median follow-up of 5.7 years, the SC group comprised 2,005 patients, resulting in a standardized incidence ratio of 1.5 (95% confidence interval [CI], 1.4-1.6) in men and 1.7 (95% CI, 1.6-1.9) in women, as compared with the general population. Use of CT/positron emission tomography (PET) was significantly higher in the SC group (p<0.001). However, the CRD of CT/PET was not significantly different between the SC group and the alive HA group (median effective dose [ED], 93 mSv for the SC group and alive HA group, respectively, p=0.510). After including TACE (n= 9,004 [44.9%], median frequency 2), total CRD was not significantly different between the SC group and the alive HA group. CRD >300 mSv significantly increased the risk of second malignant neoplasms in the subgroup with >7 years of follow-up (YFU) (hazard ratio [HR] 2.01, 95% CI 1.38-2.92, p<0.001). Second cancers in digestive organs and respiratory-intrathoracic organs were significantly increased by CRD in the subgroup with >300 mSv and over 7 YFU (HR 2.41, 95% CI 1.26-4.62; HR 5.69, 95% CI 1.62-20.04, respectively, p<0.01). TACE did not affect the increased risk of second cancers in digestive and respiratory organs in the subgroup >300 mSv and over 7 YFU. Conclusions: The risk of second cancers increased in HCC patients who survived over 7 years with CRD >300 mSv. Consideration of alternative monitoring tests and guidelines for reducing radiation exposure is crucial for long-term HCC survivors.

Radiation-induced changes in DNA methylation and their relationship to chromosome aberrations in nuclear power plant workers

Purpose: We investigated the association between occupational radiation exposure and DNA methylation changes in nuclear power plant workers. We also evaluated whether radiation- induced DNA methylation alterations are associated with chromosome aberrations.Materials and methods: The study population included 170 radiation-exposed workers and 30 controls. We measured global, long interspersed nuclear element-1 (LINE-1), and satellite 2 methylation levels in blood leukocyte DNA. The analysis of chromosome aberrations was performed on peripheral lymphocytes.Results: Global DNA methylation levels were lower in radiation-exposed workers than in controls. The methylation levels were negatively associated with the recent 1.5-year radiation dose in a multiple linear regression model (β = − 0.0088, p ≤ 0.001); the levels increased proportionally with the total cumulative dose in radiation-exposed workers. LINE-1 methylation levels were higher in radiation-exposed workers than in controls and were significantly associated with the total cumulative radiation dose in a multiple linear regression model (β = − 0.031, p = 0.035). Global DNA methylation levels were also correlated with chromosome aberrations among workers. Workers with low global methylation levels had a higher frequency of chromosome aberrations than did subjects with high global methylation levels.Conclusion: Occupational exposure to low-dose radiation could affect DNA methylation levels, and the radiation-induced DNA methylation alterations may be associated with chromosome aberrations.

The effects of multiple high-resolution peripheral quantitative computed tomography scans on bone healing in a rabbit radial bone defect model

The use of in vivo high-resolution computed tomography (CT) scanners provides the unique opportunity for evaluating temporal progression in healing of bone defects. However, these in vivo scanners impose ionizing radiation that could affect the healing and morphology of the bone. The primary objective of this study was to determine the effects of in vivo scanning at 2-week intervals on bone healing of a critical sized radial defect in rabbits and to investigate the effect of this radiation protocol on bone marrow cell viability using clinically applicable radiation doses. Thirty male rabbits were randomized into three groups: two groups received a 15mm defect in the left radius that was filled with an autologous bone graft (DEF-CT and DEF-SHAM), and one group acted as an intact control (INT-CT). The duration of the study was 6weeks. DEF-CT and INT-CT had high-resolution CT scans performed at 2-week intervals. The total cumulative radiation dose was 81.6mGy per animal. DEF-SHAM received sham CT scans at the same time points. In group DEF-CT, the bone volume (BV) in the defect increased significantly over time (p≤0.002, for all comparisons); the bone mineral density (BMD) in the defect decreased over time and was significantly lower at weeks 4 and 6 than at weeks 0 and 2 (p<0.001, for all comparisons). In group INT-CT, BV and BMD did not change over time (p=1, for all comparison). The BV (p=0.50) and the BMD (p=0.37) in the defect as measured by microCT scan during ex vivo analysis was not significantly different between DEF-CT and DEF-SHAM. Similarly, histomorphometry showed no significant difference in the total bone area (p=0.22) and percentage bone within the defect (p=0.24) between these groups.Bone marrow analysis of the left (radiated) and right (non-radiated) radius of the INT-CT group via a Colony Forming Units (CFU) assay demonstrated an average of 25.3 and 28.5 colonies for radiated and non-radiated radii, respectively (p=0.72).In conclusion, there was no significant difference in bone healing between radiated and non-radiated radius defects in rabbits. This is an important finding as it demonstrates that serial in vivo high resolution-CT imaging can not only provide accurate tissue regeneration data, but it can also be used to reduce the number of temporal cohorts within an experimental design.

Abstract No. 97: Evaluation of a two-stage approach for insertion of the hemodialysis reliable outflow (HeRO) vascular access device in patients with central venous occlusion

sure in dialysis patients who often present to interventional radiology multiple times over the course of their disease, requiring both line placement and evaluation of dialysis circuits without understanding of cumulative dose. Materials and Methods: Our QI database was queried for patients undergoing dialysis acess evaluation between July 1st to October 1st, as this was when we began recoding fluoroscopic dose in dose area product (DAP) in the medical record. A retrospective chart review of 37 consecutive patients was performed to determine the total number of dialysis interventions performed extending back to the beginning of electronic medical records in 2007. Based on the data obtained from July to October 2011, an average DAP was calculated per procedure type, namely dialysis circuit evaluations (which included graft declots and fistulograms) and dialysis line placements for access issues. This calculated DAP was used to estimate a total cumulative radiation dose based on the total number of procedures performed per patient. Results: A total of 37 patients with a mean age of 54, range 21-96 years old, were evaluated. 59.5% of these patients were 50 years old. The mean number of dialysis circuit evaluations per patient was 5 with a range of 1-30. The mean number of dialysis line placements per patient was 3 with a range of 0-17. The average estimated dose per procedure was 29.1 Gy-cm2 for dialysis circuit evaluations and 6.38 Gy-cm2 for dialysis line placement. For comparison, 2 dialysis circuit evaluations is similar to 1 coronary angiogram (mean 60.2 Gy-cm2). Overall, the average estimated cumulative dose per patient over the course of multiple dialysisrelated procedures in IR was 164 Gy-cm2 (range 29-886 Gy-cm2). Conclusion: Although more prospective data is required, it seems clear through a brief evaluation of a single institution’s dialysis patients, that cumulative radiation dosage to this subset of patients over time and multiple repeat procedures is significant. Further evaluation of how to longitudinally track and limit radiation dosage to this challenging group of patients is required to minimize potential long-term stochastic effects.

Reirradiation after salvage surgery and microvascular free flap reconstruction for recurrent head and neck carcinoma

To evaluate the outcome and complications of reirradiation of recurrent head and neck cancer after salvage surgery and microvascular reconstruction. Retrospective. Twelve patients underwent salvage surgery with microvascular reconstruction for recurrent or second primary head and neck cancer in a previously irradiated field. Median prior radiation therapy dose was 63.0 Gy. Patients then underwent postoperative reirradiation, and received a median total cumulative radiation dose of 115.0 Gy. Three (25%) patients experienced acute complications (<3 months) during reirradiation. Four (33%) patients developed grade 3 or 4 late reirradiation complications (>3 months). There were no incidences of free flap failure, brain necrosis, spinal cord injury, or carotid rupture. The incidence of soft tissue necrosis and osteoradionecrosis was 8%. Six (50%) patients are alive without evidence of recurrent disease a median of 40 months after reirradiation. Microvascular free flaps allow for maximal resection and reliable reconstruction of previously irradiated cancers before high dose reirradiation and may reduce the incidence of severe late complications and treatment related mortality.

Reirradiation After Surgery and Microvascular Reconstruction

Problem To evaluate the outcome and complications of reirradiation of recurrent head and neck cancer after salvage surgery and microvascular reconstruction. Methods Retrospective Study. Twelve patients underwent salvage surgery with microvascular reconstruction for recurrent or new primary head and neck cancer in a previously irradiated field. Median prior RT dose was 63.0 Gy (range 30.0–72.8). Patients then underwent postoperative reirradiation, receiving a median total cumulative radiation dose of 115.0 Gy. Results Three patients (25%) experienced acute complications (&lt;3 months) during reirradiation that resolved with conservative care. Four patients (33%) developed grade 3 or 4 late reirradiation complications (&gt;3 months). There were no incidences of free flap failure. No patients suffered brain necrosis, spinal cord injury, or carotid rupture. The incidence of soft tissue necrosis and osteoradionecrosis was 8%. There were no treatment-related mortalities. Six patients (50%) are alive without evidence of recurrent disease a median of 40 months after reirradiation (range 4–64 months). Conclusion Free flap reconstruction followed by reirradiation is not associated with an increased risk of perioperative, acute, or late complications. Microvascular free flaps allow for maximal resection and reliable reconstruction of previously irradiated cancers before high dose reirradiation, and may reduce the incidence of severe late complications and treatment related mortality. Significance Reirradiation for recurrent head and neck squamous cell carcinoma remains controversial. However, increasing evidence has demonstrated improved survival and locoregional control with reirradiation at the cost of potentially severe or sometimes fatal radiation toxicity. We hypothesize that using well-vascularized tissue and bone at the time of salvage surgery can reduce the incidence of reirradiation complications. This would allow patients at high risk for recurrence to more safely receive a second course of radiation therapy. To our knowledge this is the first report of the effects of microvascular reconstruction on complications and outcomes of patients undergoing salvage surgery and external beam reirradiation.

Influence of Dose Rate on Survival Time for 239 PuO 2 -Induced Radiation Pneumonitis or Pulmonary Fibrosis in Dogs

Beagle dogs were exposed once or repeatedly to 0.75-microns-diameter monodisperse aerosols of 239PuO2 by pernasal inhalation. The dogs that were exposed once received alveolar depositions (+/- standard deviation) of 3.9 +/- 1.9 kBq/kg body mass and accumulated doses of 23 +/- 8 Gy to the lung before death at 5.4 +/- 1.7 years after exposure. Dogs exposed repeatedly received a total alveolar deposition of 5.3 +/- 0.9 kBq/kg body mass during 7 to 10 semiannual exposures and accumulated doses of 22 +/- 5 Gy to the lung before death at 4.9 +/- 0.7 years after first exposure. Clearance of the plutonium from the lung in the dogs exposed repeatedly was slower than in the dogs exposed once. All dogs in the repeated-exposure study and all but one dog in the single-exposure study died from radiation effects. Pulmonary fibrosis accounted for 72% of the radiation-related deaths in the single-exposure study and 87% in the repeated-exposure study. The remaining dogs died with pulmonary cancer. Based on total cumulative radiation dose, the times after exposure to death from radiation pneumonitis and pulmonary fibrosis were not significantly different for single and repeated exposures. Thus dose rate does not appear to be an important factor in predicting death from radiation pneumonitis or pulmonary fibrosis for dogs inhaling 239PuO2.