Radiation dose and excess risk of cancer in children undergoing neuroangiography. AJR Am J Roentgenol. 2009;193:1621-1628. [PMID: 19933657 DOI: 10.2214/ajr.09.2352]

Radiation exposure during orthodontic treatment: risk to children and adolescents

OBJECTIVES

To estimate radiation risk to children and adolescents during orthodontic treatment by retrieving number and type of radiographs from the patient records.

MATERIAL AND METHODS

Radiographs, along with justifications for radiation exposure, were obtained retrospectively from the patient records of 1,790 children and adolescents referred to two Swedish orthodontic clinics. Data were grouped according to treatment stage: treatment planning, treatment, and follow-up. Estimated risk was calculated using the concept of effective dose.

RESULTS

Each patient had received around seven radiographs for orthodontic purposes. The most common exposures during treatment planning were one panoramic, one lateral, and three intraoral periapical radiographs. A small number of patients received a tomographic examination (8.2%). Few justifications for treatment planning and follow-up, but more in the actual treatment stage, had been recorded. The most common examinations were to assess root resorption and the positions of unerupted teeth, or simply carry out an unspecified control. The estimated risk of developing fatal cancer was considered low. The radiation risk from orthodontic treatment was equivalent to about 5-10 days of natural background radiation.

CONCLUSIONS

Children and adolescents sometimes undergo multiple radiographic examinations, but despite the low radiation burden, accumulated radiation exposure should be considered and justified in young patients.

Full-body MR imaging: a retrospective study on a novel diagnostic approach for children sustaining high-energy trauma

Purpose

Severe accidents are the leading cause of long-term impairment and death in children. A common diagnostic procedure for children exposed to high-injury trauma is full-body contrast-enhanced CT (fbCT). However, the number of fbCT without detected injuries is relevant. In 2007, full-body MRI (fbMRI) was implemented as a diagnostic approach for children sustaining high-energy trauma.

The aim of this cross-sectional retrospective study was to analyze fbMRI as a diagnostic tool for children after high-energy trauma focusing on feasibility, radiological findings, and limitations.

Methods

Diagnostics using fbMRI (from apex of the head to the pelvis) was performed if a child was stable and suffered a high-energy trauma in a Level I Trauma Center in Germany. 105 fbMRIs in patients exposed to high-energy trauma aged ≤ 16 years were performed between January 2007 and December 2018. Four fbMRIs were excluded as conducted for reasons other than trauma. Time between arrival in the emergency department and fbMRI, additional diagnostic procedures, injuries, and non-trauma related pathologies were analyzed.

Results

Mean time between arrival in the emergency department and fbMRI was 71 min (± SD 132 min). Two scans were discontinued and changed to a faster diagnostic procedure. 45% of children had additional X-rays and 11% CT scans. The MRIs showed intracranial abnormalities in 27%, extremities injuries in 26%, spinal injuries in 18%, pelvic, and thoracic injuries in 7% of the cases.

Conclusion

Overall fbMRI is a diagnostic alternative for hemodynamically stable, conscious children after high-energy trauma with the advantages of a radiation-free technique. However, MRI diagnostics take longer than CT scans. Prospective studies will be needed to identify the limiting factors of fbMRIs as primary diagnostic procedure compared to CT scans.

Trial registration

German Clinical Trials Register (DRKS; DRKS00017015).

Level of evidence

Case series, level of evidence V.

Radiation Exposure in Pediatric Interventional Procedures

The article is part of the series of articles on radiation protection. You can find further articles in the special section of the CVIR issue. The expanding applications of interventional procedures coupled with the potential harmful effects of ionizing radiation highlight the need to assess the delivered radiation dose and establish an effective radiation protection program, particularly in the radiosensitive pediatric population. Given the complexity and heterogeneity of interventional procedures as well as the unique characteristics of children, the management of radiation dose is proving to be quite challenging. The aim of the current article is to provide an overview of the radiation exposure in pediatric patients during interventional procedures focusing on the importance of radiation protection in the pediatric population, the reported radiation doses and the techniques of minimizing radiation dose.

Radiation Exposure Associated With Computed Tomography in Childhood and the Subsequent Risk of Cancer: A Meta-Analysis of Cohort Studies

Background:

Computed tomography (CT) is used worldwide; however, recent studies suggest that CT radiation exposure during childhood may be a risk factor for cancer, although the data are inconsistent.

Methods:

A comprehensive search of electronic databases including PubMed, SpringerLink, Embase, Cochrane Library, Elsevier/ScienceDirect, Medline, Orbis, and Web of Science databases from January 1990 to November 2018 for observational epidemiologic studies reporting associations between radiation exposure from CT in childhood and the subsequent risk of cancer was conducted. A linear model was used to explore the dose–response relationship.

Results:

Seven studies with 1180 987 children enrolled were included. The risk of later cancer was 1.32-fold higher for children exposed to CT than those without exposure. Compared to those not exposed to pediatric CT, the relative risk (RRs) were larger for the higher doses but with wider CIs (RR for 5-10 mGy: 0.90, 95% CI: 0.69-1.12; RR for 10-15 mGy: 1.02, 95% CI: 0.86-1.18; RR for >15 mGy: 1.13, 95% CI: 0.97-1.30), the leukemia risk was higher in exposed children (RR: 1.23, 95% CI: 1.10-1.36), and brain cancer risk was higher in exposed children (RR: 1.54, 95% CI: 0.84-2.45).

Conclusions:

Our analysis suggested that radiation exposure from CT during childhood is associated with a subsequently elevated risk of cancer. However, caution is needed when interpreting these results because of the heterogeneity among the studies. The findings should be confirmed in further studies with longer follow-up periods.

Eye lens radiation exposure in paediatric interventional treatment of retinoblastoma

Retinoblastoma represents 3% of cancers in children under fifteen years of age. The standard paediatric treatment for saving the affected eye is supraselective intra-arterial chemotherapy performed in interventional rooms. In order to address the radiation toxicity due to the angiography, the aim of this study was to determine the typical dose value corresponding to the procedure, estimate the paediatric patients' eye lens dose and study the relationship between dose indicators and dose to the lens. An automatic dose management software was installed in two interventional rooms to obtain the distribution of the dose indicators kerma-area product and reference-point air kerma, getting a typical value 16 Gy·cm2 and 130 mGy, respectively (n = 35). The eye lens dose estimates were obtained with photoluminescent dosimeters placed on the patient's eyelids. In the left eye, the entrance surface air kerma was 44.23 ± 2.66 mGy, and 12.72 ± 0.89 mGy in the right eye (n = 10). There was a positive correlation between dose to the lens per procedure and dose indicators, with R2 > 0.65 for both eyes. Based on this information, the threshold for the onset of radiation-induce cataracts (500 mGy) will be exceeded if the treatment is performed for more than 8 sessions.

Patient radiation doses and reference levels in pediatric interventional radiology

OBJECTIVES

To describe, in a multicentric paediatric population, reference levels (RLs) for three interventional radiological procedures.

METHODS

From January 2012 to March 2015, children scheduled for an interventional radiological procedure in two French tertiary centres were retrospectively included and divided into four groups according to age: children younger than 2 years (A1), aged 2-7 years (A5), 8-12 years (A10) and 13-18 years (A15). Three procedures were identified: cerebral digital subtraction angiography (DSA), brain arteriovenous malformation (bAVM) embolization, and head and neck superficial vascular malformation (SVM) percutaneous sclerotherapy. Demographic and dosimetric data, including dose area product (DAP), were collected.

RESULTS

550 procedures were included. For DSA (162 procedures), the proposed RL values in DAP were 4, 18, 12 and 32 Gy∙cm² in groups A1, A5, A10 and A15, respectively. For bAVM embolization (258 procedures), values were 33, 70, 105 and 88 Gy∙cm² in groups A1, A5, A10 and A15, respectively. For SVM sclerotherapy (130 procedures), values were 350, 790, 490 and 248 mGy∙cm² in groups A1, A5, A10 and A15, respectively.

CONCLUSION

Consecutive data were available to permit a proposal of reference levels for three major paediatric interventional radiology procedures.

KEY POINTS

• We determined reference levels (RLs) for bAVM embolization, DSA and SVM sclerotherapy. • The proposed RLs will permit benchmarking practice with an external standard. • The proposed RLs by age may help to develop paediatric dose guidelines.

Projected cancer risks potentially related to past, current, and future practices in paediatric CT in the United Kingdom, 1990-2020

BACKGROUND

To project risks of developing cancer and the number of cases potentially induced by past, current, and future computed tomography (CT) scans performed in the United Kingdom in individuals aged <20 years.

METHODS

Organ doses were estimated from surveys of individual scan parameters and CT protocols used in the United Kingdom. Frequencies of scans were estimated from the NHS Diagnostic Imaging Dataset. Excess lifetime risks (ELRs) of radiation-related cancer were calculated as cumulative lifetime risks, accounting for survival probabilities, using the RadRAT risk assessment tool.

RESULTS

In 2000-2008, ELRs ranged from 0.3 to 1 per 1000 head scans and 1 to 5 per 1000 non-head scans. ELRs per scan were reduced by 50-70% in 2000-2008 compared with 1990-1995, subsequent to dose reduction over time. The 130 750 scans performed in 2015 in the United Kingdom were projected to induce 64 (90% uncertainty interval (UI): 38-113) future cancers. Current practices would lead to about 300 (90% UI: 230-680) future cancers induced by scans performed in 2016-2020.

CONCLUSIONS

Absolute excess risks from single exposures would be low compared with background risks, but even small increases in annual CT rates over the next years would substantially increase the number of potential subsequent cancers.

Radiation Dose from 3D Rotational vs. Conventional 2D Digital Subtraction Angiography in Intracranial Aneurysm Coiling

Purpose: To compare patient effective dose resulting from two alternative imaging protocols for pre-coiling assessment of intracranial aneurysms: a series of 2D Digital Subtraction Angiography (DSA) projections, and a 3D rotational angiography (RA) acquisition. Methods: In a retrospective analysis, we investigated 44 patients who underwent endovascular coiling in our institution. Images were acquired on a biplane Image Intensifier system not equipped with dose-area product (DAP) meter. Conventional 2D DSA images were simulated with an anthropomorphic skull phantom. Entrance skin dose was measured with a 60 cc ion chamber, and the PCXMC Monte Carlo based software was used to calculate patient effective dose. For the RA protocol, a 16 cm computed tomography (CT) dosimetry phantom and a 100 mm pencil ion chamber were employed to measure the CT dose index. Patient effective dose was calculated with the ImPACT calculator. An unpaired two-tailed t-test was used to determine the significance of differences between patient doses in each group. Results: Sixteen patients underwent the 2D DSA protocol with multiple projections; their mean number of cine runs was 5.1; the mean effective dose was 2.11 millisievert (mSv) (range 1.69–3.43 mSv). Twenty eight patients were assessed using the 3D RA protocol with the effective dose of 1.29 mSv. The difference between the means of two dose distributions was statistically significant (p=0.00028). Conclusion: Our study demonstrated that the patient effective dose was significantly lower from the 3D RA protocol than that from the 2D DSA protocol used in the planning of coiling of intracranial aneurysm.

Esophageal Visualization as an Adjunct to the Videofluoroscopic Study of Swallowing

Objective

Complaints of dysphagia for solids lead to speech-language pathology (SLP) referral. Yet many of these patients are later diagnosed with esophageal rather than oropharyngeal dysphagia. Fluoroscopic screening involving the oropharynx alone fails to identify these patients. The aim of this study was to investigate the prevalence of esophageal abnormalities in an SLP-led videofluoroscopic study of swallowing (VFSS) clinic.

Study Design

Prospective, observational study.

Setting

Radiology suite, public hospital.

Subjects and Methods

In total, 111 consecutive mixed-etiology patients referred to the clinic by otorhinolaryngology (ORL) (59) or by a speech-language pathologist (52) were recruited. A VFSS was performed according to protocol, and at completion, esophageal visualization (in anterior-posterior plane) was performed by administration of a large liquid barium bolus and a barium capsule. All VFSS recordings were analyzed using objective digital measures of timing and displacement.

Results

Sixty-eight percent of patients had an abnormal esophageal transit. One-third of those referred presented exclusively with esophageal abnormalities, while one-third had both oropharyngeal and esophageal abnormalities. Oral abnormalities, reduced pharyngoesophageal segment maximum opening (PESmax), and increasing age were significantly associated with esophageal abnormalities.

Conclusion

Fluoroscopic evaluation of the pharynx alone, without esophageal review, risks incomplete diagnosis of patients with esophageal disorders. Using esophageal visualization allows timely referral for further investigation by appropriate medical specialties, avoiding incomplete management of patients with dysphagia.

Adjunctive techniques for optimization of ocular hemodynamics in children undergoing ophthalmic artery infusion chemotherapy

PURPOSE

To develop a reproducible technique for selective ophthalmic artery infusion chemotherapy (SOAIC) that is technically efficacious in children with unfavorable patterns of ophthalmic artery (OA) flow.

MATERIALS AND METHODS

Initially, all SOAIC was performed with intention to treat using a standard selective OA (microcatheter) infusion technique (sSOAIC). Temporary balloon occlusion (TBO) of the external carotid artery (ECA), a balloon-assisted SOAIC (bSOAIC) technique, was performed only if OA angiography did not show robust and sustained anterograde OA flow. In our more recent experience, all SOAIC was performed with intention to treat by bSOAIC. Verapamil infusion into the OA and internal carotid artery was performed in selected cases. Technical success was defined as delivery of chemotherapeutic agent(s) into the OA with robust and sustained anterograde perfusion. sSOAIC was considered to have failed if converted to bSOAIC.

RESULTS

19 eyes were treated in 17 patients (age 5 months to 16 years) between December 2008 and May 2013. Eighty-three procedures were undertaken and the OA was successfully catheterized in all. Technical success was achieved in 35/41 (85%) sSOAIC cases and 42/42 (100%) bSOAIC cases. TBO of the ECA augmented anterograde OA flow and converted all cases of retrograde OA flow to anterograde. Verapamil further augmented anterograde ocular perfusion during SOAIC. There were no access site complications, strokes, or deaths.

CONCLUSIONS

TBO of the ECA is a safe, effective, and reproducible method for optimizing ocular hemodynamics during SOAIC regardless of baseline OA flow pattern. Verapamil infusion may further favorably modify OA flow.

TRIAL REGISTRATION NUMBER

NCT01466855.

Radiation risks associated with serial imaging in colorectal cancer patients: Should we worry?

To provide an overview of the radiation related cancer risk associated with multiple computed tomographic scans required for follow up in colorectal cancer patients. A literature search of the PubMed and Cochrane Library databases was carried out and limited to the last 10 years from December 2012. Inclusion criteria were studies where computed tomographic scans or radiation from other medical imaging modalities were used and the risks associated with ionizing radiation reported. Thirty-six studies were included for appraisal with no randomized controlled trials. Thirty-four of the thirty-six studies showed a positive association between medical imaging radiation and increased risk of cancer. The radiation dose absorbed and cancer risk was greater in children and young adults than in older patients. Most studies included in the review used a linear, no-threshold model to calculate cancer risks and this may not be applicable at low radiation doses. Many studies are retrospective and ensuring complete follow up on thousands of patients is difficult. There was a minor increased risk of cancer from ionizing radiation in medical imaging studies. The radiation risks of low dose exposure (< 50 milli-Sieverts) are uncertain. A clinically justified scan in the context of colorectal cancer is likely to provide more benefits than harm but current guidelines for patient follow up will need to be revised to accommodate a more aggressive approach to treating metastatic disease.

Neurointerventions in children: radiation exposure and its import

BACKGROUND AND PURPOSE

Neurointerventions in children have dramatically improved the clinical outlook for patients with previously intractable cerebrovascular conditions, such as vein of Galen malformations and complex arteriovenous fistulas. However, these complex and sometimes lengthy procedures are performed under fluoroscopic guidance and thus unavoidably expose vulnerable pediatric patients to the effects of ionizing radiation. Recent epidemiologic evidence from a national registry of children who underwent CT scans suggests a higher-than-expected incidence of secondary tumors. We sought to calculate the predicted risk of secondary tumors in a large cohort of pediatric neurointerventional patients.

MATERIALS AND METHODS

We reviewed our cohort of pediatric neurointerventions, tabulated radiation dose delivered to the skin, and calculated the range of likely brain-absorbed doses by use of previously developed mathematical models. The predicted risk of secondary tumor development as a function of brain-absorbed dose in this cohort was then generated by use of the head CT registry findings.

RESULTS

Maximal skin dose and brain-absorbed doses in our cohort were substantially lower than have been previously described. However, we found 1) a statistically significant correlation between radiation dose and age at procedure, as well as number and type of procedures, and 2) a substantial increase in lifetime predicted risk of tumor above baseline in the cohort of young children who undergo neurointerventions.

CONCLUSIONS

Although neurointerventional procedures have dramatically improved the prognosis of children facing serious cerebrovascular conditions, the predicted risk of secondary tumors, particularly in the youngest patients and those undergoing multiple procedures, is sobering.

Superselective ophthalmic artery infusion of melphalan for intraocular retinoblastoma: preliminary results from 140 treatments

PURPOSE

To report our experience in superselective ophthalmic artery infusion of melphalan (SOAIM) for intraocular retinoblastoma.

METHODS

  From June 2008 to October 2010, 38 patients (18 women, 20 men; age range at first treatment, 7 months to 22 years) with 41 eyes with retinoblastoma were scheduled for SOAIM, for 17 newly diagnosed retinoblastomas Tumour, Node and Metastasis (TNM) 7th Edition 1a (n = 1), 1b (n = 1), 2a (n = 7), 2b (n = 4) and 3a (n = 4) and 24 retinoblastomas with partial remission/relapse TNM 7th Edition 1b (n = 13), 2a (n = 1) and 2b (n = 10). Eight patients (ten eyes) have been treated by SOAIM alone. Follow-up was 6-27 months in 28 patients (30 eyes).

RESULTS

Ophthalmic artery cannulation failed in two patients. Thirty-six patients underwent 140 treatments by internal (n = 112) or external (n = 28) carotid arteries. No major procedural complications occurred. Two patients have been lost to follow-up. Remaining 34 patients (37 eyes) had no metastatic disease. Four patients suffered permanent ocular complications: chorioretinal dystrophy (n = 2), ptosis (n = 1) and strabismus/exotropia (n = 1). Eight (22%) eyes in eight (24%) patients underwent enucleation: 7/16 (43%) newly diagnosed retinoblastomas and 1/22 (4.5%) retinoblastomas undergoing partial remission/relapse. For all treated eyes, Kaplan-Meier eye enucleation-free rates (K-M) were 85.4% (95% CI, 73.3-97.5%), 74.4% (95% CI, 57-91.8%) and still stable at 6, 12 months and 2 years, respectively. For eyes with partial remission/relapse, and eyes at presentation, K-M at 2 years were 95.5% (95% CI, 86.9-100%) and 45.6% (95% CI, 16.6-74.6%), respectively.

CONCLUSION

Superselective ophthalmic artery infusion of melphalan was safe and powerful, especially following other therapies. Superselective ophthalmic artery infusion of melphalan should be added to focal therapies spectrum. In selected cases, melphalan should be combined with other chemotherapeutic agents.

Avaliação de exposições médicas em procedimentos pediátricos de radiologia intervencionista

OBJETIVO: Avaliar as exposições pediátricas de radiologia intervencionista em dois hospitais do Estado da Bahia, visando contribuir para a construção de um cenário estadual e nacional, possibilitando o conhecimento das exposições e da necessidade de sua otimização, visto que as peculiaridades que envolvem a radiologia e a pediatria se potencializam quando se trata de procedimentos de radiologia intervencionista, em razão das doses elevadas de radiação. MATERIAIS E MÉTODOS: Foram avaliados 32 procedimentos em quatro salas nos dois principais hospitais que realizam procedimentos de radiologia intervencionista pediátrica na Bahia. Foram avaliados os valores de kerma no ar incidente e o produto kerma-área no ar de 27 procedimentos cardiológicos e 5 procedimentos cerebrais. RESULTADOS: Os valores máximos de produto kerma-área e kerma obtidos para procedimentos cardiológicos foram, respectivamente, 129,9 Gy.cm² e 947,0 mGy, e para procedimentos cerebrais, 83,3 Gy.cm² e 961,0 mGy. CONCLUSÃO: Os resultados deste estudo mostraram valores de exposições superiores em até 14 vezes os obtidos em estudos realizados em outros países, chegando próximos de resultados obtidos para procedimentos em adultos. Isto revela quão elevadas podem ser as exposições pediátricas, indicando a necessidade de constante otimização dos procedimentos e avaliação das exposições.

Radiation dose features and solid cancer induction in pediatric computed tomography

Over the past two decades technical advances and improvements have made computed tomography (CT) a valuable and essential tool in the array of diagnostic imaging modalities. CT uses ionizing radiation (X-rays) which may damage DNA and increase the risk of carcinogenesis. This is especially pertinent in pediatric CT as children are more radiosensitive and have a longer life expectancy than adults. The purpose of this paper is to review and elucidate the potential harmful effects of ionizing radiation in terms of solid cancer induction from pediatric CT scanning. In the light of scientific and technical developments, we will also discuss the possible strategies and ongoing efforts to reduce CT radiation exposure in pediatric patients. In this context, we will not ignore the fact that a well-justified CT scan may exceed its risk and have a favorable impact.

The predictive value of 3D time-of-flight MR angiography in assessment of brain arteriovenous malformation obliteration after radiosurgery

BACKGROUND AND PURPOSE

The purpose of radiosurgery of bAVMs is complete angiographic obliteration of its nidus. We assessed the diagnostic accuracy of 1.5T T2-weighted MR imaging and TOF-MRA images for detecting nidus obliteration after radiosurgery.

MATERIALS AND METHODS

The pre- and postradiosurgery MR images and DSA images from 120 patients who were radiosurgically treated for a bAVM were re-evaluated by 2 observers for patency of the nidus (preradiosurgery) and obliteration (postradiosurgery: final follow-up MR imaging), by using a 3-point scale of confidence. Consensus reading of the DSA after radiosurgery was considered the criterion standard for obliteration. Sensitivity, specificity, PPVs, and NPVs, and overall diagnostic performance by using ROC were determined.

RESULTS

Mean bAVM volume during radiosurgery was 3.4 mL (95% CI, 2.6-4.3 mL). Sixty-six patients (55%) had undergone previous endovascular embolization. The mean intervals between radiosurgery and follow-up MR imaging and for DSA, respectively, were 35.6 months (95% CI, 32.3-38.9 months) and 42.1 months (95% CI, 40.3-44.0 months). With ROC, an area under curve of 0.81-0.83 was found. PPVs of final follow-up MR-imaging for definitive obliteration varied between 0.89 [corrected] and 0.95. NPV was 0.52 [corrected] . An average false-positive rate, meaning overestimation of nidus obliteration of 0.10 [corrected] and an average false-negative rate, meaning underestimation of nidus obliteration of 0.42 [corrected] were found.

CONCLUSIONS

MRA is insufficient to diagnose obliteration in the follow-up of bAVMs after radiosurgery. A remaining nidus diameter <10 mm seems to be the major limiting factor for reliable assessment of obliteration. We highly recommend follow-up DSA for definitive diagnosis of complete obliteration.