Cancer risks attributable to low doses of ionizing radiation: assessing what we really know

Safety Considerations in MRI and CT

OBJECTIVE

MRI and CT are indispensable imaging modalities for the evaluation of patients with neurologic disease, and each is particularly well suited to address specific clinical questions. Although both of these imaging modalities have excellent safety profiles in clinical use as a result of concerted and dedicated efforts, each has potential physical and procedural risks that the practitioner should be aware of, which are described in this article.

LATEST DEVELOPMENTS

Recent advancements have been made in understanding and reducing safety risks with MR and CT. The magnetic fields in MRI create risks for dangerous projectile accidents, radiofrequency burns, and deleterious interactions with implanted devices, and serious patient injuries and deaths have occurred. Ionizing radiation in CT may be associated with shorter-term deterministic effects on biological tissues at extremely high doses and longer-term stochastic effects related to mutagenesis and carcinogenesis at low doses. The cancer risk of radiation exposure in diagnostic CT is considered extremely low, and the benefit of an appropriately indicated CT examination far outweighs the potential risk. Continuing major efforts are centered on improving image quality and the diagnostic power of CT while concurrently keeping radiation doses as low as reasonably achievable.

ESSENTIAL POINTS

An understanding of these MRI and CT safety issues that are central to contemporary radiology practice is essential for the safe and effective treatment of patients with neurologic disease.

Role of MR enterography versus ileo-colonoscopy in the assessment of inflammatory bowel diseases

Background

Inflammatory bowel disease (IBD) is widespread and rapidly rising in developing countries. It remains a significant issue in Western culture with a prevalence of more than 0.3%. Symptom control has been the only focus of treatment before the discovery that many individuals with IBD continue to have disease activity even in the absence of clinical symptoms. Therefore, treatment goals now include establishing clinical remission, steroid-free remission, and mucosal healing, which may eventually be complemented by transmural healing in cross-sectional imaging modalities. Magnetic resonance enterography (MRE), computed tomography enterography, and small-bowel ultrasound are now reliable methods for staging intramural lesions and extramural consequences in CD and for determining disease activity and severity. Recently literature suggests the incorporation of (MRE) for periodic reevaluation of IBD patients, as it offers small-bowel, colonic, and extra-enteric assessment as well as monitors the response to the anti-inflammatory therapy. The purpose of the current study was to compare MRE with ileo-colonoscopy findings in the diagnosis of IBD features, specifically Crohn's disease, and ulcerative colitis, as well as in the detection of disease exacerbation (Activity).

Results

This study used MRE and ileo-colonoscopy to assess chronic inflammatory bowel disease patients; the patient population (n = 30) was made up of (14/30, 46.7%) females and (16/30, 53.3%) males, with a mean age of 32 ± SD 13 years. MRE alone detected lymphadenopathy in 73.3% of patients, and mural thickening with a mean of 4.1 ± SD 5.1 mm. It has detected mucosal enhancement with 80% sensitivity and 60% specificity. However, it was unable to detect mucosal erosions or ulceration.

Conclusions

MRE is sensitive, inexpensive, noninvasive, and radiation-free for inflammatory bowel disease detection, with 86.7% diagnostic accuracy for affected areas. Unlike ileo-colonoscopy, it could examine the entire small intestine, precisely measure the affected loop, and detect activity signs such as mural thickening and lymphadenopathy. Only ileo-colonoscopy could detect mucosal degradation and superficial ulcers. IBD treatment protocols should incorporate MRE for small-bowel, colonic, and extra-enteric assessment, monitoring of disease activity, and anti-inflammatory therapy response.

Estimation of radiation doses and lifetime attributable risk of radiation-induced cancer in the uterus and prostate from abdomen pelvis CT examinations

Computed tomography (CT) scans are one of the most common radiation imaging modalities, and CT scans are rising steadily worldwide. CT has the potential to enhance radiography practice, but it also has the risk of drastically increasing patient doses. One CT procedure for the abdomen pelvis (AP) area can expose a patient's prostate or uterus to a substantial radiation dose, leading to concerns about radiation-induced cancer. This study aimed to estimate organ doses of the uterus and prostate and evaluate the lifetime attributable risk (LAR) of cancer incidence and mortality resulting from AP CT examinations. This retrospective study included 665 patients, of which 380 (57%) were female, and 285 (43%) were male. Data were collected from the picture archiving and communication system for AP CT procedures and exposure parameter data. Organ doses for the uterus and prostate were calculated using National Cancer Institute CT (NCICT) software. Based on the risk models proposed by the BEIR VII report, the calculated organ doses were used to estimate the LAR of prostate and uterus cancer incidence and mortality due to radiation exposure from AP CT procedures. The mean effective dose resulting from AP CT for females and males was 5.76 ± 3.22 (range: 1.13-12.71 mSv) and 4.37 ± 1.66 mSv (range: 1.36-8.07 mSv), respectively. The mean organ dose to the uterus was 10.86 ± 6.09 mGy (range: 2.13-24.06 mGy). The mean organ dose to the prostate was 7.00 ± 2.66 mGy (range: 2.18-12.94 mGy). The LAR of uterus and prostate cancer incidence was 1.75 ± 1.19 cases and 2.24 ± 1.06 cases per 100,000 persons, respectively. The LAR of cancer mortality rates from uterus and prostate cancers were 0.36 ± 0.22 and 0.48 ± 0.18 cases per 100,000 persons, respectively. The LAR of prostate and uterus cancer occurrence and mortality from radiation doses with AP CT procedures was low but not trivial. Therefore, efforts should be made to lower patient doses while retaining image quality. Although the minimization of the patient's radiation dose must guide clinical practice, the estimated slight increase in risk could aid in easing fears regarding well-justified AP CT procedures.

The Influence of Body Mass Index on Radiation Dose and Exposure Time in Fluoroscopic Guided Hip Injections - A Comparative Analysis of Two Approaches

Objectives

Intra-articular hip injections (IHI) are routinely performed for both diagnostic and therapeutic purposes. The procedure can be performed via either an anterior or a lateral approach with fluoroscopic guidance being widely practised. There is a risk of radiation exposure associated with fluoroscopy assisted IHI. This may be influenced either by the surgical approach or the patient's body mass index (BMI) or both. This study was undertaken to compare the relationships of the respective approaches to BMI, fluoroscopic exposure time (FET) and radiation dose (RD).

Methods

A retrospective study was conducted comprising 74 patients who underwent IHI with 37 patients in each group (anterior and lateral). Patients were assessed pre-operatively and post operatively for any complications. The intra-operative radiation dose, fluoroscopic exposure time and BMI data were collected and analyzed.

Results

The mean age of the patients in anterior and lateral groups was 61.18±14.08 and 67.21±14.39 years respectively. No complications were noted in either group. However, there was a significant increase in FET (P=0.002) and RD (P<0.001) in patients with BMI ≥ 30. In the lateral group, this trend was markedly noted with increase in FET (P<0.001) and RD (P<0.001) in patients with BMI ≥ 30. On the other hand, in the anterior group there was no statistically significant increase in FET (P=0.155) and only a moderate increase in RD (P=0.020) in patients with BMI ≥ 30.

Conclusion

Both anterior and lateral approaches to fluoroscopic guided IHI are equally safe in terms of complications involved. There is statistically significant increase in both radiation dose and fluoroscopic exposure time in patients with BMI ≥ 30. This is more pronounced in lateral approach. The anterior approach is most effective in reducing both radiation dose and fluoroscopic exposure time, more so in patients with BMI of 30 and above.

Cancer and Radiosensitivity Syndromes: Is Impaired Nuclear ATM Kinase Activity the Primum Movens?

There are a number of genetic syndromes associated with both high cancer risk and clinical radiosensitivity. However, the link between these two notions remains unknown. Particularly, some cancer syndromes are caused by mutations in genes involved in DNA damage signaling and repair. How are the DNA sequence errors propagated and amplified to cause cell transformation? Conversely, some cancer syndromes are caused by mutations in genes involved in cell cycle checkpoint control. How is misrepaired DNA damage produced? Lastly, certain genes, considered as tumor suppressors, are not involved in DNA damage signaling and repair or in cell cycle checkpoint control. The mechanistic model based on radiation-induced nucleoshuttling of the ATM kinase (RIANS), a major actor of the response to ionizing radiation, may help in providing a unified explanation of the link between cancer proneness and radiosensitivity. In the frame of this model, a given protein may ensure its own specific function but may also play additional biological role(s) as an ATM phosphorylation substrate in cytoplasm. It appears that the mutated proteins that cause the major cancer and radiosensitivity syndromes are all ATM phosphorylation substrates, and they generally localize in the cytoplasm when mutated. The relevance of the RIANS model is discussed by considering different categories of the cancer syndromes.

Black Bone MRI for Virtual Surgical Planning in Craniomaxillofacial Surgery

Advances in computer-aided design and computer-aided manufacturing software have improved translational applications of virtual surgical planning (VSP) in craniomaxillofacial surgery, allowing for precise and accurate fabrication of cutting guides, stereolithographic models, and custom implants. High-resolution computed tomography (CT) imaging has traditionally been the gold standard imaging modality for VSP in craniomaxillofacial surgery but delivers ionizing radiation. Black bone magnetic resonance imaging (MRI) reduces the risks related to radiation exposure and has comparable functionality when compared with CT for VSP. Our group has studied the accuracy of utilizing black bone MRI in planning and executing several types of craniofacial surgeries, including cranial vault remodeling, maxillary advancement, and mandibular reconstruction using fibular bone. Here, we review clinical applications of black bone MRI pertaining to VSP and three-dimensional (3D)-printed guide creation for craniomaxillofacial surgery. Herein, we review the existing literature and our institutional experience comparing black bone MRI and CT in VSP-generated 3D model creation in cadaveric craniofacial surgeries including cranial vault reconstruction, maxillary advancement, and mandibular reconstruction with fibular free flap. Cadaver studies have demonstrated the ability to perform VSP and execute the procedure based on black bone MRI data and achieve outcomes similar to CT when performed for cranial vault reshaping, maxillary advancement, and mandibular reconstruction with free fibula. Limitations of the technology include increased time and costs of the MRI compared with CT and the possible need for general anesthesia or sedation in the pediatric population. VSP and 3D surgical guide creation can be performed using black bone MRI with comparable accuracy to high-resolution CT scans in a wide variety of craniofacial reconstructions. Successful segmentation, VSP, and 3D printing of accurate guides from black bone MRI demonstrate potential to change the preoperative planning standard of care. Black bone MRI also reduces exposure to ionizing radiation, which is of particular concern for the pediatric population or patients undergoing multiple scans.

Development and Validation of a Mobile Application for Measuring Tibial Torsion

BACKGROUND

Tibial torsion lacks a single and reliable method for its measurement. While physical examination, computed tomography (CT), and EOS imaging are used complementarily, three-dimensional (3D) CT is the most widely used method for intuitive documentation and visualization. However, concern regarding the associated radiation hazard limits its use in the evaluation of pediatric patients. Moreover, EOS machines are too expensive and too large to be placed in every clinic requiring the measurement of tibial torsion. Therefore, a new method for 3D reconstruction is needed. In the present study, we tested the validity and reliability of a novel reconstruction tool for the lower leg.

METHODS

A statistical shape model and Laplacian constraint were adopted for the development of a new reconstruction tool for measuring tibial torsion. Tibial torsion measurements based on a 3D reconstruction application and CT images for 36 patients were evaluated for intraobserver and interobserver reliability. Tibial torsion measurements for 75 patients were compared for validation.

RESULTS

A 3D reconstruction system for the lower leg was developed as a mobile application and was installed in a portable device for easy access in the clinical setting. In terms of interobserver reliability, the intraclass correlation coefficient among 3 clinicians was 0.896 (95% confidence interval [CI], 0.828 to 0.941). The correlation coefficient between tibial torsion measured with use of 3D CT and that measured with the mobile application was 0.865 (p < 0.001).

CONCLUSIONS

The mobile application showed excellent reliability and validity for measuring tibial torsion. Concurrent utilization with mobile application for the femur allows visualization of the rotational profile of the leg without the need for CT or EOS.

LEVEL OF EVIDENCE

Diagnostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Radiation Exposure and Lifetime Attributable Risk of Cancer Incidence and Mortality from Low- and Standard-Dose CT Chest: Implications for COVID-19 Pneumonia Subjects

Since the novel coronavirus disease 2019 (COVID-19) outbreak, there has been an unprecedented increase in the acquisition of chest computed tomography (CT) scans. Nearly 616 million people have been infected by COVID-19 worldwide to date, of whom many were subjected to CT scanning. CT exposes the patients to hazardous ionizing radiation, which can damage the genetic material in the cells, leading to stochastic health effects in the form of heritable genetic mutations and increased cancer risk. These probabilistic, long-term carcinogenic effects of radiation can be seen over a lifetime and may sometimes take several decades to manifest. This review briefly describes what is known about the health effects of radiation, the lowest dose for which there exists compelling evidence about increased radiation-induced cancer risk and the evidence regarding this risk at typical CT doses. The lifetime attributable risk (LAR) of cancer from low- and standard-dose chest CT scans performed in COVID-19 subjects is also discussed along with the projected number of future cancers that could be related to chest CT scans performed during the COVID-19 pandemic. The LAR of cancer Incidence from chest CT has also been compared with those from other radiation sources, daily life risks and lifetime baseline risk.

Ultrasound-Guided percutaneous laser disc decompression (PLDD) with fluoroscopic validation for the treatment of cervical disc herniation: Technical note

OBJECTIVE

Percutaneous laser disc decompression (PLDD) has been regarded as an effective alternative for the treatment of cervical soft disc herniations. Repeated X-Ray scanning is essential when performing this technique.

DESIGN

Technical note.

METHODS

We present a new method for the treatment of cervical disc herniation using ultrasound to guide the needle entry to the cervical disc, to avoid excess of radiation exposure during the surgical procedure. We evaluated the efficacy of this cervical approach.We retrospectively reviewed the clinical data of 14 cases who underwent a PLDD under ultrasound (US) guidance for the treatment of contained cervical disc herniation using a 1470 Nm diode laser. The lower cervical discs (C5-C6 and C6-C7) were the most affected sites, accounting for 78.6% of surgical discs.A significant NRS reduction between baseline and 1 month (p = 0.0002) and between baseline and 12 months (p = 0.0007) was observed.

CONCLUSIONS

Our results support the conclusion that US guided PLDD with fluoroscopic validation is a minimally invasive technique for patients affected by herniated cervical discs, but proper choice of patients is critical. This approach should not be performed except after adequate training under close supervision of surgeons experienced in this procedure and in interventional US.

The Evidence for Excess Risk of Cancer and Non-Cancer Disease at Low Doses and Dose Rates

The question of whether there are excess radiation-associated health risks at low dose is controversial. We present evidence of excess cancer risks in a number of (largely pediatrically or in utero exposed) groups exposed to low doses of radiation (<0.1 Gy). Moreover, the available data on biological mechanisms do not provide support for the idea of a low-dose threshold or hormesis for any of these endpoints. There are emerging data suggesting risks of cardiovascular disease and cataract at low doses, but this is less well established. This large body of evidence does not suggest and, indeed, is not statistically compatible with any very large threshold in dose (>10 mGy), or with possible beneficial effects from exposures. The presented data suggest that exposure to low-dose radiation causes excess cancer risks and quite possibly also excess risks of various non-cancer endpoints.

Advantages of CT Versus MRI for Preoperative Assessment of Osteochondritis Dissecans of the Capitellum

BACKGROUND

Magnetic resonance imaging (MRI) is considered to be the gold standard for imaging of osteochondritis dissecans (OCD).

PURPOSE/HYPOTHESIS

The purpose was to determine the additional value of a preoperative computed tomography (CT) scan in adolescent patients with capitellar OCD of the elbow. Consistent with the fact that OCD is a lesion involving the subchondral bone, the hypothesis was that CT would be superior to MRI for imaging OCD of the capitellum.

STUDY DESIGN

Cohort study (diagnosis); Level of evidence, 3.

METHODS

All patients being treated surgically for an OCD of the capitellum between 2006 and 2016 at one institution were reviewed for preoperative imaging. A total of 28 patients met the inclusion criteria. Corresponding MRI and CT scans were compared retrospectively. Multiple parameters were recorded, with special emphasis on OCD lesion size, fragmentation, and tilt as well as joint surface integrity, loose bodies, and osteophytes.

RESULTS

The OCD lesions were best seen on CT scans, whereas MRI T1-weighted images overestimated and T2-weighted images underestimated the size of defects. A subchondral fracture nonunion was found on CT scans in 18 patients, whereas this was seen on MRI T1-weighted images in only 2 patients (P < .001) and MRI T2-weighted images in 4 patients (P < .001). Fragmentation of the OCD fragment was found on CT scans in 17 patients but on MRI scans in only 9 patients (P = .05). Osteophytes as a sign of secondary degenerative changes were seen on CT scans in 24 patients and were seen on MRI scans in 15 patients (P = .02). Altogether, only 51 of 89 secondary changes including loose bodies, effects on the radial head and ulnohumeral joint, and osteophytes that were seen on CT scans were also seen on MRI scans (P = .002).

CONCLUSION

OCD fragmentation and secondary changes were more often diagnosed on CT. These factors indicate OCD instability or advanced OCD stages, which are indications for surgery. In an adolescent who is considered at risk for OCD (baseball, gymnastics, weightlifting, tennis) and who has lateral elbow joint pain with axial or valgus load bearing, CT is our imaging modality of choice for diagnosing and staging OCD of the capitellum.

CT Scans and Cancer Risks: A Systematic Review and Dose-response Meta-analysis

BACKGROUND

There is still uncertainty on whether ionizing radiation from CT scans can increase the risks of cancer. This study aimed to identify the association of cumulative ionizing radiation from CT scans with pertaining cancer risks in adults.

METHODS

Five databases were searched from their inception to November 15, 2020. Observational studies reporting cancer risks from CT scans in adults were included. The main outcome included quantified cancer risks as cancer case numbers in exposed/unexposed adult participants with unified converted measures to odds ratio (OR) for relative risk, hazard ratio. Global background radiation (2.4 mSv per year) was used as control for lifetime attribution risk (LAR), with the same period from incubation after exposure until survival to 100 years.

RESULTS

25 studies were included with a sum of 111,649,943 participants (mean age: 45.37 years, 83.4% women), comprising 2,049,943 actual participants from 6 studies with an average follow-up period as 30.1 years (range, 5 to 80 years); 109,600,000 participants from 19 studies using LAR. The cancer risks for adults following CT scans were inordinately increased (LAR adults, OR, 10.00 [95% CI, 5.87 to 17.05]; actual adults, OR, 1.17 [95%CI, 0.89 to 1.55]; combined, OR, 5.89 [95%CI, 3.46 to 10.35]). Moreover, cancer risks elevated with increase of radiation dose (OR, 33.31 [95% CI, 21.33 to 52.02]), and multiple CT scan sites (OR, 14.08 [95% CI, 6.60 to 30.05]). The risk of solid malignancy was higher than leukemia. Notably, there were no significant differences for age, gender, country, continent, study quality and studying time phrases.

CONCLUSIONS

Based on 111.6 million adult participants from 3 continents (Asia, Europe and America), this meta-analysis identifies an inordinately increase in cancer risks from CT scans for adults. Moreover, the cancer risks were positively correlated with radiation dose and CT sites. The meta-analysis highlights the awareness of potential cancer risks of CT scans as well as more reasonable methodology to quantify cancer risks in terms of life expectancy as 100 years for LAR.

PROSPERO TRIAL REGISTRATION NUMBER

CRD42019133487.

Bone marrow chimerism breaks the barrier to pancreatic islet transplantation

In their recent Cell Reports paper, Chang and colleagues report on a successful strategy to achieve durable mixed hematopoietic chimerism that promotes the engraftment and long-term function of pancreatic islet allotransplants in fully immunocompetent mice without immunosuppression.

Value of Repeat CT Brain in Mild Traumatic Brain Injury Patients with High Risk of Intracerebral Hemorrhage Progression

Patients with mild traumatic brain injury (MTBI) with intracerebral hemorrhage (ICH), particularly those at higher risk of having ICH progression, are typically prescribed a second head Computer Tomography (CT) scan to monitor the disease development. This study aimed to evaluate the role of a repeat head CT in MTBI patients at a higher risk of ICH progression by comparing the intervention rate between patients with and without ICH progression.

METHODS

192 patients with MTBI and ICH were treated between November 2019 to December 2020 at a single level II trauma center. The Glasgow Coma Scale (GCS) was used to classify MTBI, and initial head CT was performed according to the Canadian CT head rule. Patients with a higher risk of ICH progression, including the elderly (≥65 years old), patients on antiplatelets or anticoagulants, or patients with an initial head CT that revealed EDH, contusional bleeding, or SDH > 5 mm, and multiple ICH underwent a repeat head CT within 12 to 24 h later. Data regarding types of intervention, length of stay in the hospital, and outcome were collected. The risk of further neurological deterioration and readmission rates were compared between these two groups. All patients were followed up in the clinic after one month or contacted via phone if they did not return.

RESULTS

189 patients underwent scheduled repeated head CT, 18% had radiological intracranial bleed progression, and 82% had no changes. There were no statistically significant differences in terms of intervention rate, risk of neurological deterioration in the future, or readmission between them.

CONCLUSION

Repeat head CT in mild TBI patients with no neurological deterioration is not recommended, even in patients with a higher risk of ICH progression.

A new technique useful for lumbosacral percutaneous pedicle screw placement without fluoroscopy or computer-aided navigation systems

BACKGROUND

Percutaneous pedicle screw (PPS) placements in the lumbosacral spine generally rely on fluoroscopy at the expense of radiation exposure. Our accumulated experience in open PS placements without fluoroscopic guidance realized a consistent shift toward PPS insertion with newly developed devices, which require neither fluoroscopy nor navigation. We wish to report our new technique and evaluations of its accuracy.

METHODS

Our equipment consisted of a pedicle targeting tool to identify and escort the cannulated awl to the correct starting point for cortical bone perforation and a cannulated awl-probe system with a guidewire to maintain the optimal position throughout the subsequent surgical steps. The surgeon could advance the blunt-tipped probe searching for the cancellous bone track using tactile feedback as experienced in open techniques. A 2-year period of transition from a free-hand (1169 screws in 286 patients) to the new PPS technique (1933 screws in 413 patients) allowed accuracy comparison between the two procedures using postoperative CT scans.

RESULTS

Compared with the open-group, the PPS-group showed a lower rate of fully contained intrapedicular PS placements at L1 through S1, as a whole (90.7% vs 85.4%), but not at L4 through S1 (89.9% vs 90.2%). Less-accurate PPS placements at upper than lower lumbar spines in part reflect intended pedicle perforations laterally as a trade-off for avoiding facet violation immediately above the most cephalad screw. The PPS-group also had a higher incidence of PS-related transient nerve root complications (0% vs 1.7%). These values for the PPS-group, however, fell within those previously reported for free-hand or fluoroscopy techniques.

CONCLUSIONS

Our new PPS technique, although useful for eliminating the potential risk of repeated radiation exposure, fell short of reaching the accuracy of the free-hand technique. Nerve integrity monitoring with PS stimulation, which we currently use, will help further improve the technical precision.

STUDY DESIGN

Original Article. The study was approved by our institutional review boad (2,019,231).

The emerging role of exosomes in radiotherapy

Presently, more than half of cancer patients receive radiotherapy to cure localized cancer, palliate symptoms, or control the progression of cancer. However, radioresistance and radiation-induced bystander effects (RIBEs) are still challenging problems in cancer treatment. Exosomes, as a kind of extracellular vesicle, have a significant function in mediating and regulating intercellular signaling pathways. An increasing number of studies have shown that radiotherapy can increase exosome secretion and alter exosome cargo. Furthermore, radiation-induced exosomes are involved in the mechanism of radioresistance and RIBEs. Therefore, exosomes hold great promise for clinical application in radiotherapy. In this review, we not only focus on the influence of radiation on exosome biogenesis, secretion and cargoes but also on the mechanism of radiation-induced exosomes in radioresistance and RIBEs, which may expand our insight into the cooperative function of exosomes in radiotherapy.

Single step track dilatation for percutaneous nephrolithotomy in children

Introduction and objectives

Data on the use of single step dilatation technique during pediatric percutaneous nephrolithotomy (PCNL) in the literature is sparse. In this prospective randomized study, we aimed to compare the safety, efficacy, and perioperative complications of single step versus serial tract dilatation using Alken metal telescopic dilators during pediatric PCNL.

Methods

Patients undergoing PCNL were randomized into two groups according to the dilatation technique used. In group A, Alken telescopic serial metal dilatation was utilized, and in group B, single step dilatation was performed. Inclusion criteria included children < 18 years with stone burden from 2 to 4 cm, located in the renal pelvis ± one calyx, who were candidates for PCNL.

The primary outcomes were access time and complications’ rate. The secondary outcomes were dilatation fluoroscopy time, operative duration, stone free rate, postoperative hospital stay, hemoglobin deficit, and need for blood transfusion. Both outcomes were evaluated and compared between both treatment groups.

Results

A total of 70 patients were randomized into group A (35 patients) and group B (35 patients). Access was successfully obtained in all procedures. All the procedures were performed through a single tract.

Access time and dilatation fluoroscopy time were shorter in group B (statistically significant). Patients in group A had higher rate of complications (statistically significant). Intraoperative bleeding requiring blood transfusion was less in single track dilatation than serial metal track dilatation.

Conclusions

Compared to serial metal track dilatation, single step dilatation showed comparable operative time and stone free rate, with significantly reduced access time and dilatation fluoroscopy time.

Low-Dose Radiation Affects Cardiovascular Disease Risk in Human Aortic Endothelial Cells by Altering Gene Expression under Normal and Diabetic Conditions

High doses of ionizing radiation can cause cardiovascular diseases (CVDs); however, the effects of <100 mGy radiation on CVD remain underreported. Endothelial cells (ECs) play major roles in cardiovascular health and disease, and their function is reduced by stimuli such as chronic disease, metabolic disorders, and smoking. However, whether exposure to low-dose radiation results in the disruption of similar molecular mechanisms in ECs under diabetic and non-diabetic states remains largely unknown; we aimed to address this gap in knowledge through the molecular and functional characterization of primary human aortic endothelial cells (HAECs) derived from patients with type 2 diabetes (T2D-HAECs) and normal HAECs in response to low-dose radiation. To address these limitations, we performed RNA sequencing on HAECs and T2D-HAECs following exposure to 100 mGy of ionizing radiation and examined the transcriptome changes associated with the low-dose radiation. Compared with that in the non-irradiation group, low-dose irradiation induced 243 differentially expressed genes (DEGs) (133 down-regulated and 110 up-regulated) in HAECs and 378 DEGs (195 down-regulated and 183 up-regulated) in T2D-HAECs. We also discovered a significant association between the DEGs and the interferon (IFN)-I signaling pathway, which is associated with CVD by Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, protein−protein network analysis, and module analysis. Our findings demonstrate the potential impact of low-dose radiation on EC functions that are related to the risk of CVD.

Congenital Heart Disease and the Risk of Cancer: An Update on the Genetic Etiology, Radiation Exposure Damage, and Future Research Strategies

Epidemiological studies have shown an increased prevalence of cancer in patients with congenital heart disease (CHD) as compared with the general population. The underlying risk factors for the acquired cancer risk remain poorly understood, and shared genetic anomalies and cumulative radiation exposure from repeated imaging and catheterization procedures may be contributing factors. In the present review, we provide an update on the most recent literature regarding the associations between CHD and cancer, with a particular focus on genetic etiology and radiation exposure from medical procedures. The current evidence indicates that children with CHD may be a high-risk population, already having the first genetic “hit”, and, consequently, may have increased sensitivity to ionizing radiation from birth or earlier. Future research strategies integrating biological and molecular measures are also discussed in this article.

Hyper-radiosensitivity affects low-dose acute myeloid leukemia incidence in a mathematical model

In vitro experiments show that the cells possibly responsible for radiation-induced acute myeloid leukemia (rAML) exhibit low-dose hyper-radiosensitivity (HRS). In these cells, HRS is responsible for excess cell killing at low doses. Besides the endpoint of cell killing, HRS has also been shown to stimulate the low-dose formation of chromosomal aberrations such as deletions. Although HRS has been investigated extensively, little is known about the possible effect of HRS on low-dose cancer risk. In CBA mice, rAML can largely be explained in terms of a radiation-induced Sfpi1 deletion and a point mutation in the remaining Sfpi1 gene copy. The aim of this paper is to present and quantify possible mechanisms through which HRS may influence low-dose rAML incidence in CBA mice. To accomplish this, a mechanistic rAML CBA mouse model was developed to study HRS-dependent AML onset after low-dose photon irradiation. The rAML incidence was computed under the assumptions that target cells: (1) do not exhibit HRS; (2) HRS only stimulates cell killing; or (3) HRS stimulates cell killing and the formation of the Sfpi1 deletion. In absence of HRS (control), the rAML dose-response curve can be approximated with a linear-quadratic function of the absorbed dose. Compared to the control, the assumption that HRS stimulates cell killing lowered the rAML incidence, whereas increased incidence was observed at low doses if HRS additionally stimulates the induction of the Sfpi1 deletion. In conclusion, cellular HRS affects the number of surviving pre-leukemic cells with an Sfpi1 deletion which, depending on the HRS assumption, directly translates to a lower/higher probability of developing rAML. Low-dose HRS may affect cancer risk in general by altering the probability that certain mutations occur/persist.

Are we aware of radiation: A study about necessity of diagnostic X-ray exposure

BACKGROUND

Total exposure to ionizing radiation has nearly doubled in the last two decades. This increase is primarily due to increased computed tomography (CT) exposure. Concerns have been raised about the risks associated with patients' exposure to medical imaging radiation, which can increase a person's lifetime risk of developing cancer. Preventing unnecessary examinations becomes critical at this point. To avoid unnecessary examinations, it is necessary to understand the demanding process.

AIM

To ascertain clinicians' awareness of and reasons for requesting a CT examination.

METHODS

We developed an online questionnaire that included 20 questions about clinicians' awareness of radiation safety and their reasons for requesting a CT examination, as well as demographic information such as age, gender, and year of medical practice experience. Additionally, we asked participants the number of CT scans requested in a month, the patients' questions and approaches about the imaging method, the effect of the patient's previous imaging history on the current imaging request, whether they believed that they had sufficient information about radiation doses, and whether they requested CT without an indication. We administered the questionnaire to clinicians from a variety of different professions in four different cities.

RESULTS

A total of 195 clinicians participated. Internal medicine specialists were the most crowded group (38/195, 19.5%). Mean age of the population was 33.66 ± 5.92 years. Mean year of experience was 9.01 ± 5.96. Mean number of requested CT scans in a month was 36.88 ± 5.86. Forty-five (23.1%) participants stated that they requested CT scans without clinical indication. The most common reasons for CT scan requests were work load, fear of malpractice, and patient demand/insistence.

CONCLUSION

CT scan requests are influenced by a variety of factors, both internal and external to the doctors and patients. Raising awareness of radiation safety and reducing fear of malpractice by limiting the number of patients per physician may result in a reduction in unnecessary CT examinations and ionizing radiation exposure.

Trends in Inpatient Utilization of Head Computerized Tomography Scans in the United States: A Brief Cross-Sectional Study

Background

Although computed tomography (CT) has revolutionized the field of medicine due to its incredible diagnostic capabilities, the trends regarding the usage of CT scans, especially in the field of neuroscience, are not very clear. We aim to find the trends in the usage of inpatient head CT scans in the United States using a robust database. 

Methods

We queried the national inpatient usage of head CT scans in the United States from 1997 to 2014 using a robust national database. The trends in usage were analyzed based on age, gender, insurance types, and patients’ income. 

Results

During the study period, we recorded a total of 5,309,329 head CT scans, of which 51% were female. The total number of head CT scans in the United States dropped significantly from 527,026 cases to 181,095 cases (p=0.000). The decrease was with a steep slope from 1997 to 2002, and since then the decreasing slope turned to a steady state. The decrease in head CT scans was significant in all age groups (p = 0.001), more significant in uninsured payers (-79.4%, p=0.000), and prominent in low-income patients (-70.5 %, p=0.000).

Conclusions

Our study showed that national inpatient usage of CT scans of the head significantly decreased during the past two decades. This decrease is presumably multifactorial: reducing the number of unnecessary radiations, increased appropriateness audits by the government, payers’ payment reductions, and integrated electronic platforms.

Dose-Response Effects of Low-Dose Ionizing Radiation on Blood Parameters in Industrial Irradiation Workers

While previous studies have focused on the health effects of occupational exposure of radiations on medical radiation workers, few have analyzed the dose-response relationship between low radiation doses and changes in blood parameters. Even fewer studies have been conducted on industrial worker populations. Using a prospective cohort study design, this study collected health examination reports and personal dose monitoring data from 705 industrial irradiation workers who underwent regular physical examinations at Dongguan Sixth People’s Hospital. The dose-response effects of low-dose ionizing radiation on blood parameters were assessed using a generalized linear model and restricted cubic spline model. Red blood cell counts decreased then increased, before decreasing again with increasing ionizing radiation. This was in contrast to the curve of the total platelet count after irradiation. Additionally, a radiation dose of 2.904 mSv was the turning point for the nonlinear curve of hemoglobin count changes. In conclusion, long-term, low-dose ionizing radiation affects blood cell levels in industrial irradiation workers. There is a nonlinear dose-response relationship between red blood cell, platelet, and hemoglobin counts and the cumulative radiation dose. These findings should alert radiation workers to seek preventive medical treatment before the occurrence of any serious hematopoietic disease.

The Use of Computerized Tomography Scans in Elective Knee and Hip Arthroplasty—What Do They Tell Us and at What Risk?

The average background radiation exposure in the United States has nearly doubled over the previous quarter century, with almost all the increase derived from medical imaging. Nearly 2% of all cancers in the United States may be attributable to radiation from computerized tomography (CT) scans. Given the nondiagnostic nature of CT scans that are used in elective knee and hip arthroplasty today, special consideration should be given to the inherent risk of radiation exposure with routine use of this technology. Methods to decrease radiation exposure including modulating the settings of the CT machine and using alternative non-CT-based systems can decrease patient exposure to radiation from CT scans. The rapid evolution of CT technology in arthroplasty has allowed for expanded clinical applications, the benefits of which remain controversial.

Low-Cost Probabilistic 3D Denoising with Applications for Ultra-Low-Radiation Computed Tomography

We propose a pipeline for synthetic generation of personalized Computer Tomography (CT) images, with a radiation exposure evaluation and a lifetime attributable risk (LAR) assessment. We perform a patient-specific performance evaluation for a broad range of denoising algorithms (including the most popular deep learning denoising approaches, wavelets-based methods, methods based on Mumford−Shah denoising, etc.), focusing both on accessing the capability to reduce the patient-specific CT-induced LAR and on computational cost scalability. We introduce a parallel Probabilistic Mumford−Shah denoising model (PMS) and show that it markedly-outperforms the compared common denoising methods in denoising quality and cost scaling. In particular, we show that it allows an approximately 22-fold robust patient-specific LAR reduction for infants and a 10-fold LAR reduction for adults. Using a normal laptop, the proposed algorithm for PMS allows cheap and robust (with a multiscale structural similarity index >90%) denoising of very large 2D videos and 3D images (with over 107 voxels) that are subject to ultra-strong noise (Gaussian and non-Gaussian) for signal-to-noise ratios far below 1.0. The code is provided for open access.

Could Ultrasound Be Used as a Triage Tool in Diagnosing Fractures in Children? A Literature Review

Fracture is one of the most frequent causes of emergency department visits in children, conventional radiography being the standard imaging tool used for following procedures and treatment. This imagistic method is irradiating and harmful, especially for children due to their high cell division rate. For this reason, we searched the literature to see if musculoskeletal ultrasound is a good alternative for diagnostic and follow-up regarding fractures in the pediatric population. After searching the databases using MeSH terms and manual filters, 24 articles that compare X-ray and ultrasound regarding their specificity and sensitivity in diagnosing fractures were included in this study. In the majority of the studied articles, the specificity and sensitivity of ultrasound are around 90–100%, and with high PPVs (positive predictive values) and NPVs (negative predictive values). Although it cannot replace conventional radiography, it is a great complementary tool in fracture diagnosis, having a sensitivity of nearly 100% when combined with clinical suspicion of fracture, compared with X-ray.

Characterizing and quantifying low-value diagnostic imaging internationally: a scoping review

BACKGROUND

Inappropriate and wasteful use of health care resources is a common problem, constituting 10-34% of health services spending in the western world. Even though diagnostic imaging is vital for identifying correct diagnoses and administrating the right treatment, low-value imaging-in which the diagnostic test confers little to no clinical benefit-is common and contributes to inappropriate and wasteful use of health care resources. There is a lack of knowledge on the types and extent of low-value imaging. Accordingly, the objective of this study was to identify, characterize, and quantify the extent of low-value diagnostic imaging examinations for adults and children.

METHODS

A scoping review of the published literature was performed. Medline-Ovid, Embase-Ovid, Scopus, and Cochrane Library were searched for studies published from 2010 to September 2020. The search strategy was built from medical subject headings (Mesh) for Diagnostic imaging/Radiology OR Health service misuse/Medical overuse OR Procedures and Techniques Utilization/Facilities and Services Utilization. Articles in English, German, Dutch, Swedish, Danish, or Norwegian were included.

RESULTS

A total of 39,986 records were identified and, of these, 370 studies were included in the final synthesis. Eighty-four low-value imaging examinations were identified. Imaging of atraumatic pain, routine imaging in minor head injury, trauma, thrombosis, urolithiasis, after thoracic interventions, fracture follow-up and cancer staging/follow-up were the most frequently identified low-value imaging examinations. The proportion of low-value imaging varied between 2 and 100% inappropriate or unnecessary examinations.

CONCLUSIONS

A comprehensive list of identified low-value radiological examinations for both adults and children are presented. Future research should focus on reasons for low-value imaging utilization and interventions to reduce the use of low-value imaging internationally.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO: CRD42020208072.

Within-subject effects of standardized prosthetic socket modifications on physical function and patient-reported outcomes

Background

Among the challenges of living with lower limb loss is the increased risk of long-term health problems that can be either attributed directly to the amputation surgery and/or prosthetic rehabilitation or indirectly to a disability-induced sedentary lifestyle. These problems are exacerbated by poorly fit prosthetic sockets. There is a knowledge gap regarding how the socket design affects in-socket mechanics and how in-socket mechanics affect patient-reported comfort and function. The objectives of this study are (1) to gain a better understanding of how in-socket mechanics of the residual limb in transfemoral amputees are related to patient-reported comfort and function, (2) to identify clinical tests that can streamline the socket design process, and (3) to evaluate the efficacy and cost of a novel, quantitatively informed socket optimization process.

Methods

Users of transfemoral prostheses will be asked to walk on a treadmill wearing their current socket plus 8 different check sockets with designed changes in different structural measurements that are likely to induce changes in residual limb motion, skin strain, and pressure distribution within the socket. Dynamic biplane radiography and pressure sensors will be used to measure in-socket residual limb mechanics. Patient-reported outcomes will also be collected after wearing each socket. The effects of in-socket mechanics on both physical function and patient-reported outcomes (aim 1) will be assessed using a generalized linear model. Partial correlation analysis will be used to examine the association between research-grade measurements and readily available clinical measurements (aim 2). In order to compare the new quantitative design method to the standard of care, patient-reported outcomes and cost will be compared between the two methods, utilizing the Wilcoxon-Mann-Whitney non-parametric test (aim 3).

Discussion

Knowledge on how prosthetic socket modifications affect residual bone and skin biomechanics itself can be applied to devise future socket designs, and the methodology can be used to investigate and improve such designs, past and present. Apart from saving time and costs, this may result in better prosthetic socket fit for a large patient population, thus increasing their mobility, participation, and overall health-related quality of life.

Trial registration

ClinicalTrials.gov NCT05041998. Date of registration: Sept 13, 2021.

Assessing and conveying risks and benefits of imaging in neonates using ionizing radiation and sedation/anesthesia

Neonates represent a unique subset of the pediatric population that requires special attention and careful thought when implementing advanced cross-sectional imaging with CT or MRI. The ionizing radiation associated with CT and the sedation/anesthesia occasionally required for MRI present risks that must be balanced against the perceived benefit of the imaging examination in the unique and particularly susceptible neonatal population. We review the perceived risks of ionizing radiation and the more concrete risks of sedation/anesthesia in term and preterm neonates in the context of an imaging paradigm. When the expected diagnostic yield from CT and MRI is similar, and sedation is required for MRI but not for CT, CT likely has the higher benefit-to-risk ratio in the neonate. However, despite the risks, the most appropriate imaging modality should always be chosen after thoughtful consideration is given to each unique patient and informed discussions including radiology, anesthesia, neonatology and the parents/caregivers are pursued.

In vitro relationships of galactic cosmic radiation and epigenetic clocks in human bronchial epithelial cells

Ionizing radiation is a well-appreciated health risk, precipitant of DNA damage, and contributor to DNA methylation variability. Nevertheless, relationships of ionizing radiation with DNA methylation-based markers of biological age (i.e. epigenetic clocks) remain poorly understood. Using existing data from human bronchial epithelial cells, we examined in vitro relationships of three epigenetic clock measures (Horvath DNAmAge, MiAge, and epiTOC2) with galactic cosmic radiation (GCR), which is particularly hazardous due to its high linear energy transfer (LET) heavy-ion components. High-LET 56Fe was significantly associated with accelerations in epiTOC2 (β = 192 cell divisions, 95% CI: 71, 313, p-value = .003). We also observed a significant, positive interaction of 56Fe ions and time-in-culture with epiTOC2 (95% CI: 42, 441, p-value = .019). However, only the direct 56Fe ion association remained statistically significant after adjusting for multiple hypothesis testing. Epigenetic clocks were not significantly associated with high-LET 28Si and low-LET X-rays. Our results demonstrate sensitivities of specific epigenetic clock measures to certain forms of GCR. These findings suggest that epigenetic clocks may have some utility for monitoring and better understanding the health impacts of GCR.

Long-term investigation of environmental radioactivity levels and public health around the Qinshan Nuclear Power Plant, China

To evaluate the impact of the Qinshan Nuclear Power Plant (Qinshan NPP) in normal operation on the surrounding environment and population, the radioactivity levels of drinking water and the ambient environment, as well as the residents’ cancer incidence, were continuously monitored for a period of 9 years (2012–2020). All of the gross α and β radioactivity concentrations in drinking water were less than the WHO recommended values (0.5 Bq/L for gross α and 1 Bq/L for gross β). The results of ambient environment accumulated dose monitored by thermoluminescent dosimeters (TLDs) indicated that the ambient environment radioactive level around the Qinshan NPP is consistently at natural background radiation levels. The age-dependent annual effective doses due to the ingestion of tap water or exposure to the outdoor ambient environment are lower than the reference dose of 0.1 mSv/year. The corresponding excess risks are at relatively low levels. Thus, the consumption of drinking water and outdoor activities are not expected to give rise to any detectable adverse effects on the health of the public around the Qinshan NPP. For all cancers combined, the age-standardized incidence rate by the Chinese 2000 standard population of the inhabitants living around Qinshan NPP is consistent with that of Zhejiang Province as a whole. Based on current radiation risk estimates, radiation exposure is not a plausible explanation for any excess cancers observed in the vicinity of the Qinshan NPP.

A Brief Overview of Radiation-Induced Effects on Spermatogenesis and Oncofertility

Simple Summary

Spermatogenesis is one of the most important processes for the propagation of life; however, the testes’ ability to form sperm via this differentiation process is highly radiosensitive and easily impacted by exposure to environmental, occupational, or therapeutic radiation. Furthermore, the possibility that radiation effects on the gonads can be passed on from generation to generation should not be overlooked. This review focuses on the radiation-induced effects on spermatogenesis and the transgenerational effects. We also explore the potential of novel radiobiological approaches to improve male fertility preservation during radiotherapy.

Abstract

The genotoxicity of radiation on germ cells may be passed on to the next generation, thus its elucidation is not only a scientific issue but also an ethical, legal, and social issue in modern society. In this article, we briefly overview the effects of radiation on spermatogenesis and its associated genotoxicity, including the latest findings in the field of radiobiology. The potential role of transgenerational effects is still poorly understood, and further research in this area is desirable. Furthermore, from the perspective of oncofertility, we discuss the historical background and clinical importance of preserving male fertility during radiation treatment and the potential of microbeam radiotherapy. We hope that this review will contribute to stimulating further discussions and investigations for therapies for pediatric and adolescent/young adult patients.

Effects of provider incentives on dental X-raying in NHS Scotland: what happens if patients switch providers?

BACKGROUND

In many market settings individuals are encouraged to switch health care providers as a means of ensuring more competition. Switching may have a potentially undesirable side effect of increasing unnecessary treatment. Focusing on the most common source of medical radiation (dental X-rays), the purpose of this study was to assess whether, upon switching dentist, X-ray exposure increases depending on the type of provider payment.

METHODS

The analysis used longitudinal data from 2005 to 2016 covering a 5% random sample of the Scottish adult population covered by the National Health Service (NHS). Multiple fixed-effects panel regression analyses were employed to determine the correlation of provider remuneration with patients' likelihood of receiving an X-ray upon switching to a new dentist other things equal. A broad set of covariates including a patient's copayment status was controlled for.

RESULTS

Upon switching to a dentist who was paid fee-for-service, patients had a by 9.6%-points (95% CI 7.4-11.8%) higher probability of receiving an X-ray, compared to switching to a salaried dentist. Results were robust when accounting for patient exemption status, as well as unobserved patient and dentist characteristics.

CONCLUSIONS

In comparison to staying with the same dentist, patients may be exposed to substantially more X-rays upon switching to a dentist who is paid fee-for-service. There may need to be better guidance and regulation to protect the health of those who have to switch provider due to moving and greater caution in advocating voluntary switching.

One-stop local and whole-body staging of children with cancer

Accurate staging and re-staging of cancer in children is crucial for patient management. Currently, children with a newly diagnosed cancer must undergo a series of imaging tests, which are stressful, time-consuming, partially redundant, expensive, and can require repetitive anesthesia. New approaches for pediatric cancer staging can evaluate the primary tumor and metastases in a single session. However, traditional one-stop imaging tests, such as CT and positron emission tomography (PET)/CT, are associated with considerable radiation exposure. This is particularly concerning for children because they are more sensitive to ionizing radiation than adults and they live long enough to experience secondary cancers later in life. In this review article we discuss child-tailored imaging tests for tumor detection and therapy response assessment - tests that can be obtained with substantially reduced radiation exposure compared to traditional CT and PET/CT scans. This includes diffusion-weighted imaging (DWI)/MRI and integrated [F-18]2-fluoro-2-deoxyglucose (18F-FDG) PET/MRI scans. While several investigators have compared the value of DWI/MRI and 18F-FDG PET/MRI for staging pediatric cancer, the value of these novel imaging technologies for cancer therapy monitoring has received surprisingly little attention. In this article, we share our experiences and review existing literature on this subject.

Does Radioactive Iodine Therapy for Hyperthyroidism Cause Cancer?

Radioactive iodine has been considered a safe and effective therapeutic option for hyperthyroidism secondary to Graves disease and autonomously functioning thyroid nodules since the mid-20th century. The question of whether I-131 at the doses used for hyperthyroidism might increase the risk of cancer has been investigated in a number of observational cohort studies over the years, with the preponderance of evidence being reassuring as to its safety. In particular, the 1998 Cooperative Thyrotoxicosis Therapy Follow-up Study (CTTFUS) has been widely cited as compelling evidence that I-131 is safe in hyperthyroidism therapy with respect to carcinogenesis. However, in 2019, a study by Kitahara and colleagues re-analyzed the CTTFUS cohort, extending the follow-up time and applying a novel dosimetric model for estimating tissue absorbed doses of radiation. This new analysis concluded that radioactive iodine was associated with an increased risk for mortality from overall cancer, breast cancer, and non-breast solid cancers. Reaction to this study was vociferous and particularly negative in the nuclear medicine literature. This mini-review was inspired by the 2019 CTTFUS controversy, and it is intended to provide the necessary context for clinicians to provide nuanced advice to their patients on the subject. To that end, the pre-2019 literature is surveyed, the 2019 CTTFUS study and a 2020 follow-up are discussed, and lessons from the literature and critical commentaries are considered.

Review of the risk of cancer following low and moderate doses of sparsely ionising radiation received in early life in groups with individually estimated doses

BACKGROUND

The detrimental health effects associated with the receipt of moderate (0.1-1 Gy) and high (>1 Gy) acute doses of sparsely ionising radiation are well established from human epidemiological studies. There is accumulating direct evidence of excess risk of cancer in a number of populations exposed at lower acute doses or doses received over a protracted period. There is evidence that relative risks are generally higher after radiation exposures in utero or in childhood.

METHODS AND FINDINGS

We reviewed and summarised evidence from 60 studies of cancer or benign neoplasms following low- or moderate-level exposure in utero or in childhood from medical and environmental sources. In most of the populations studied the exposure was predominantly to sparsely ionising radiation, such as X-rays and gamma-rays. There were significant (p < 0.001) excess risks for all cancers, and particularly large excess relative risks were observed for brain/CNS tumours, thyroid cancer (including nodules) and leukaemia.

CONCLUSIONS

Overall, the totality of this large body of data relating to in utero and childhood exposure provides support for the existence of excess cancer and benign neoplasm risk associated with radiation doses < 0.1 Gy, and for certain groups exposed to natural background radiation, to fallout and medical X-rays in utero, at about 0.02 Gy.

Occupational ionizing radiation-induced skin injury among orthopedic surgeons: A clinical survey

BACKGROUND

This study aimed to assess orthopedic surgeons' attitudes and behaviors toward occupational radiation exposure and investigate the prevalence of occupational radiation-induced skin injury among orthopedic surgeons. Similarly, risk factors for the presence of radiation-induced skin injury were investigated.

METHODS

Overall, 108 orthopedic surgeons were administered self-reported questionnaires about occupational radiation exposure, and their hands were then photographed. Their fields of expertise were classified into spine, arthroplasty, sports medicine, hand, oncology, rheumatoid arthritis, pediatric orthopedic, and resident. Dermatologists evaluated the surgeons' skin conditions and classified into 3 grades of injury: grade 0, no clinical symptoms; grade 1, careful observation required; and grade 2, detailed examination required. Logistic regression analysis was performed to investigate the factors related to the presence of radiation-induced skin injury. Crude and adjusted logistic regression analysis using the backward stepwise selection method was similarly conducted. Receiver operating characteristic curve (ROC) analysis was performed to estimate the predictive power of exposure time, occupational period, and accumulated annual exposure time for radiation-induced skin injury.

RESULTS

In total, 93.5% of the surgeons were careful about occupational radiation exposure, of which 76.8% used a dosimeter. Skin changes in the hands were self-reported by 42.5% of the surgeons, and radiation-induced skin injury was diagnosed in 31.4%. The accuracy of the self-reported skin changes was 100% for grade 2 and 61.5% for grade 1. Adjusted regression analysis showed that dermatologists' diagnosis-related factors were self-reported skin changes (odds ratio [OR] 3.1) and spine surgeons (OR 3.2). ROC analysis demonstrated that an occupational period >21 years and an accumulated exposure time >6696 min were considered risk factors, with ORs of 4.07 and 5.99, respectively.

CONCLUSIONS

Orthopedic surgeons, particularly spine surgeons, should be regularly examined by dermatologists early in their careers for early detection of radiation-induced skin injury on the hands.

Radiation-induced tumors and secondary malignancies following radiotherapy

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A role for club cells in smoking-associated lung adenocarcinoma

The cellular origin of lung adenocarcinoma remains a focus of intense research efforts. The marked cellular heterogeneity and plasticity of the lungs, as well as the vast variety of molecular subtypes of lung adenocarcinomas perplex the field and account for the extensive variability of experimental results. While most experts would agree on the cellular origins of other types of thoracic tumours, great controversy exists on the tumour-initiating cells of lung adenocarcinoma, since this histologic subtype of lung cancer arises in the distal pulmonary regions where airways and alveoli converge, occurs in smokers as well as nonsmokers, is likely caused by various environmental agents, and is marked by vast molecular and pathologic heterogeneity. Alveolar type II, club, and their variant cells have all been implicated in lung adenocarcinoma progeny and the lineage hierarchies in the distal lung remain disputed. Here we review the relevant literature in this rapidly expanding field, including results from mouse models and human studies. In addition, we present a case for club cells as cells of origin of lung adenocarcinomas that arise in smokers.

Multiple lung epithelial cells are targets of carcinogenic hits. Club cells are such cells that can metabolically activate tobacco pre-carcinogens, being thus positioned as cells of origin of lung adenocarcinomas in smokers.https://bit.ly/3iOshcy

The Cardiovascular System in Space: Focus on In Vivo and In Vitro Studies

On Earth, humans are subjected to a gravitational force that has been an important determinant in human evolution and function. During spaceflight, astronauts are subjected to several hazards including a prolonged state of microgravity that induces a myriad of physiological adaptations leading to orthostatic intolerance. This review summarises all known cardiovascular diseases related to human spaceflight and focusses on the cardiovascular changes related to human spaceflight (in vivo) as well as cellular and molecular changes (in vitro). Upon entering microgravity, cephalad fluid shift occurs and increases the stroke volume (35-46%) and cardiac output (18-41%). Despite this increase, astronauts enter a state of hypovolemia (10-15% decrease in blood volume). The absence of orthostatic pressure and a decrease in arterial pressures reduces the workload of the heart and is believed to be the underlying mechanism for the development of cardiac atrophy in space. Cellular and molecular changes include altered cell shape and endothelial dysfunction through suppressed cellular proliferation as well as increased cell apoptosis and oxidative stress. Human spaceflight is associated with several cardiovascular risk factors. Through the use of microgravity platforms, multiple physiological changes can be studied and stimulate the development of appropriate tools and countermeasures for future human spaceflight missions in low Earth orbit and beyond.

Assessment of Health Professionals' Attitudes on Radiation Protection Measures

(1) Background: Health professionals' knowledge, beliefs and perceptions concerning radiation protection may affect their behaviour during surgery and consequently influence the quality of health services. This study highlights the health professionals' average knowledge level and captures the beliefs, perceptions, and behaviours in a large public Greek hospital. (2) Materials and Methods: A cross-sectional study was carried out, including health professionals working in operating rooms. One hundred thirty-two staff members participated by responding to an original questionnaire. The sample consisted of nurses, radiographers and medical doctors of various specialties involved daily in surgical procedures where ionizing radiation is required. The survey was conducted from March to June 2021, and the response rate was 97%. (3) Results: The level of overall knowledge of health professionals regarding radiation protection safety was not satisfactory. Females and employees with a lower level of education had more misconceptions about radiation and radiation protection. Employees of younger ages and with less previous experience were more likely to have negative emotions towards radiation exposure. Finally, employees with fewer children tended to express physical complaints caused by their negative emotions due to radiation exposure. (4) Conclusions: Health professionals' lack of basic and specialized knowledge concerning radiation protection safety had a negative impact on the provision of health services. The continuing training of the staff seemed to be the only solution to reverse this trend. The training should highlight how radiation exposure can be minimized, safeguarding health professionals' trust and sense of security by significantly improving their working environment.

Effects of Low-dose Gamma Radiation on Expression of Apoptotic Genes in Rat Peripheral Blood Lymphocyte

Background:

Exposure to high-dose ionizing radiation is known as a human carcinogen factor, but our information about the effects of low-dose ionizing radiation such as occupational exposures is limited. The main concern of scientific community is biological consequences due to low-dose radiations.

Objective:

This study aims to evaluate the effects of low-dose γ-radiation on expression changes of apoptotic genes (bax and bcl-2) in the rat peripheral blood lymphocytes.

Material and Methods:

In this experimental study, 42 adult male rats were classified into 6 groups, which was exposed to various doses values ranged from 20 mGy to 1000 mGy by γ-rays from a Co-60 source. Blood samples were provided for analysis of gene expression 24 h after gamma radiation by relative quantitative Reverse Transcription - Polymerase Chain Reaction (RT-PCR). Radiation sensitivity of rat lymphocytes was measured by the bax/bcl-2 ratio as a predictive marker for radio-sensitivity.

Results:

The results of this study showed that low dose of gamma radiation can induce down-regulation of bax in rat peripheral blood lymphocytes. Despite other mechanisms of cellular radio-protection, changes in expression of these apoptotic genes can be the primary pathway in responses of the lymphocytes radio-protection to the exposure. Our study revealed a significant decrease in the bax/bcl-2 ratio at 50 mGy dose compare to control and the other irradiated groups (p < 0.05).

Conclusion:

These results suggest that changes in the bax/bcl-2 ratio especially in radiation workers, as a key factor in apoptosis, can be considered as a biological marker in low-dose gamma radiation.

Expanding the Utilization of Low-Dose Computed Tomography in Plastic and Reconstructive Surgery Based on Validated Practices Among Surgical Specialties

INTRODUCTION

As computed tomography (CT) usage increases, so have concerns over radiation-induced malignancy. To mitigate these risks, low-dose CT (LDCT) has emerged as a versatile alternative by other specialties, although its use in plastic surgery remains sparse. This study aimed to investigate validated uses of LDCT across surgical specialties and extrapolate these insights to expand its application for plastic surgeons.

METHODS

A systematic review of the literature was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines using search terms "low dose CT" OR "low dose computed tomography" AND "surgery," where the name of each surgical specialty was substituted for word "surgery" and each specialty term was searched separately in combination with the 2 CT terms. Data on radiation dose, outcomes, and level of evidence were collected. Validated surgical applications were correlated with similar procedures and diagnostic tests performed routinely by plastic surgeons to extrapolate potential applications for plastic surgeons.

RESULTS

A total of 3505 articles were identified across surgical specialties, with 27 ultimately included. Depending on the application, use of LDCT led to a 25% to 97% reduction in radiation dose and all studies reported noninferior image quality and diagnostic capability compared with standard-dose CT. Potential identified uses included the following: evaluation of soft tissue infections, preoperative and postoperative management of facial and hand fractures, flap design, 3D modeling, and surgical planning.

DISCUSSION

Low-dose CT is a valid imaging alternative to standard-dose CT. Expanded utilization in plastic surgery should be considered to minimize the iatrogenic effects of radiation and to promote patient safety without compromising outcomes.

3D iterative reconstruction can do so much more than reduce dose

Recent advances in software and hardware for cardiac SPECT have the potential to revolutionize nuclear cardiology. It is easy to use these technologies to maintain the status quo and lower radiation dose, despite the fact there is very little evidence that lowering patient dose in already low dose imaging protocols confers any benefit to patients. Cardiac SPECT has tremendous potential for risk stratification, molecular tracers, and high temporal resolution management of patients with electrophysiological disorders. In addition, these new reconstruction techniques can offer spatial resolution that is comparable and sometimes even superior to PET. Lastly, recent research has also held out the potential for performing absolute blood flow qualification using SPECT instrumentation. As these new technologies become available, the goal should be to make images better and improve patient care first, then optimize the dose.

Acute outcomes of three-dimensional mapping for fluoroscopy reduction in paediatric catheter ablation for supraventricular tachycardia

BACKGROUND

Catheter ablation is a safe and effective therapy for the treatment of supraventricular tachycardia in children. Current improvements in technology have allowed progressive reduction in radiation exposure associated with the procedure. To assess the impact of three-dimensional mapping, we compared acute procedural results collected from the Catheter Ablation with Reduction or Elimination of Fluoroscopy registry to published results from the Prospective Assessment after Pediatric Cardiac Ablation study.

METHODS

Inclusion and exclusion criteria from the Prospective Assessment after Pediatric Cardiac Ablation study were used as guidelines to select patient data from the Catheter Ablation with Reduction or Elimination of Fluoroscopy registry to compare acute procedural outcomes between cohorts. Outcomes assessed include procedural and fluoroscopy exposure times, success rates of procedure, and complications.

RESULTS

In 786 ablation procedures, targeting 498 accessory pathways and 288 atrioventricular nodal reentrant tachycardia substrates, average procedural time (156.5 versus 206.7 minutes, p < 0.01), and fluoroscopy time (1.2 versus 38.3 minutes, p < 0.01) were significantly shorter in the study group. Success rates for the various substrates were similar except for manifest accessory pathways which had a significantly higher success rate in the study group (96.4% versus 93.0%, p < 0.01). Major complication rates were significantly lower in the study group (0.3% versus 1.6%, p < 0.01).

CONCLUSIONS

In a large, multicentre study, three-dimensional systems show favourable improvements in clinical outcomes in children undergoing catheter ablation of supraventricular tachycardia compared to the traditional fluoroscopic approach. Further improvements are anticipated as technology advances.

Image-Based Evaluation of Irradiation Effects in Brain Tissues by Measuring Absolute Electrical Conductivity Using MRI

Radiation-induced injury is damage to normal tissues caused by unintentional exposure to ionizing radiation. Image-based evaluation of tissue damage by irradiation has an advantage for the early assessment of therapeutic effects by providing sensitive information on minute tissue responses in situ. Recent magnetic resonance (MR)-based electrical conductivity imaging has shown potential as an effective early imaging biomarker for treatment response and radiation-induced injury. However, to be a tool for evaluating therapeutic effects, validation of its reliability and sensitivity according to various irradiation conditions is required. We performed MR-based electrical conductivity imaging on designed phantoms to confirm the effect of ionizing radiation at different doses and on in vivo mouse brains to distinguish tissue response depending on different doses and the elapsed time after irradiation. To quantify the irradiation effects, we measured the absolute conductivity of brain tissues and calculated relative conductivity changes based on the value of pre-irradiation. The conductivity of the phantoms with the distilled water and saline solution increased linearly with the irradiation doses. The conductivity of in vivo mouse brains showed different time-course variations and residual contrast depending on the irradiation doses. Future studies will focus on validation at long-term time points, including early and late delayed response and evaluation of irradiation effects in various tissue types.

Increasing radiation exposure from computed tomography in liver transplant recipients over time

OBJECTIVES

To evaluate changes in radiation exposure from computed tomography (CT) among patients undergoing liver transplantation in our unit over a 10-year period.

METHODS

We evaluated 134 elective patients, without hepatocellular carcinoma or cholangiocarcinoma who underwent transplantation in 2007-2008 and 2017-2018. CT scans performed in our hospital up to 2 years pre transplant and 1 year post transplant were evaluated.

RESULTS

There was an increase in mean estimated effective radiation dose per patient in 2017-2018 compared to 2007-2008 (77.8 mSv ± 6.2 vs 56.7 mSv ± 5.9, p < 0.05). This change was mainly due to an increased number of pre-transplant CT scans per patient (2.9 ± 0.3 vs 1.4 ± 0.14, p = 0.0001). High radiation dose scan protocols were more frequently used in 2017-2018, with 4-phase liver CT accounting for a larger proportion of scans both pre-transplant (61% vs 43%, p = 0.004) and post-transplant (29% vs 13%, p = 0.002). A greater proportion of patients were exposed to > 100 mSv of ionising radiation in the 2017-2018 patients (29% vs 11%, p < 0.01). These figures are likely to be a significant under-estimate as they exclude other imaging modalities and CT scans performed at other institutions.

CONCLUSION

Radiation exposure from diagnostic imaging has increased among liver transplant recipients at our institution over the last decade. This appears to be due to an increase in the number of CT scans performed, and a shift towards higher dose scan protocols.