Estimates Of Lifetime Attributable Risk Research Articles

Радиологический ущерб: применение новой метрики риска Международной комиссии по радиологической защите

Currently, the International Commission on Radiological Protection (ICRP) is discussing the practical application of a new radiation risk metric, called radiological detriment (RD). The concept of RD was first introduced by the ICRP in Publication 22 more than 30 years ago. At the same time, it was important to assess both the risk of radiation induced cancer development and the quality of the future life of patients. Of great interest is the comparison of RD and the lifetime attributable risk (LAR), which is currently widely used in assessing radiation safety. In this study, а comparison of RD and LAR estimates was made for the population living near the fabrication/refabrication module (FRM) of the Pilot Demonstration Energy Complex, that is currently under construction in the city of Seversk, Tomsk region. It is shown that during normal operation of the FRM and after a beyond design basis accident, the RD value is approximately 20% higher than the LAR value. Thus, the LAR value of mortality for residents of the city of Seversk during normal operation of the FRM is 40 times lower than the negligible risk level according to NRB-99/2009 (10Е-6 year-1), while the RD value remains 32 times lower than the negligible level. The simultaneous estimation of the RD and LAR values performed for the first time shows the possibility of their effective use for assessing the level of radiological protection of the population and workers.

Estimation of Lifetime Attributable Risk (LAR) of Cancer Associated with Chest Computed Tomography Procedures in Children

Purpose: The danger of radiation at low doses continues linearly, and without a threshold, investigations concluded that although the risk of cancer from Computed Tomography (CT) scans is low, it is not zero.
 This study aims to determine the patient's radiation dose and estimate the Lifetime Attributable Risk (LAR) of cancer incidence for a single chest CT scan in children.
 Materials and Methods: We divided 1,105 children into four age groups: 0 years, 5 years, 10 years, and 15 years. Dosimetric data of chest CT scan were plugged in VirtualDoseCT software, and organ dose and effective dose were calculated. The cancer risk based on organ dose is estimated according to the BEIR VII report.
 Results: The highest dose in boys was related to lung (5.13 - 6.8 mSv) and heart (5.27-5.97 mSv), and in girls, lung (4.98 - 5.91 mSv), breast (4.24 - 5.21 mSv), and heart (4.9 - 5.71 mSv) had the highest dose. The highest LAR (per 100,000) was obtained for the breast in the age group of 0 years (61.01), followed by the breast for the age group of 5 years (46.16) and lung in the age group of 0 years (43.32) in girls.
 Conclusion: This study shows a better concept of radiation dose in the chest CT scan in children and how much effective dose and organ dose values increase the cancer risk.

ОДЭК: уровень радиологической защиты населения с учётом современной модели «доза-эффект» МКРЗ

After receiving the notification of the license granting and its registration in the license register it has become topical the preparation of the final version of the project documentation to guarantee the safety of the public residing in the proximity of the operating Pilot-demonstration energy complex (PDEC), which includes a reactor unit BREST-OD-300, reprocessing module and a fuel fabrication/refabrication module. Currently International Commission on Radiological Protection (ICRP, Publication 103) recommends for estimating radiological protection of the public to use carcinogenic risks estimates for individual organs and tissues, with account of equivalent doses and modern models of «dose-effect» relationship instead of the use of committed effective doses. The article demonstrates the 5-7 times spread of lifetime carcinogenic radiation risk values from exposure to different radionuclides, while the committed effective dose from intakes of the same radionuclides do not differ. The distinguishing characteristic of updated ICRP recommendations is consideration of gender and age of the exposed population when assessing radiation-related carcinogenic risks. The article presents estimates of lifetime attributable risk for critical groups of the public residing in the proximity of the PDEC; the risk was calculated with the use of estimates of annual air emissions from normally operated PDEC. Tritium (H-3) and cesium (Cs-137) emissions limit values have been calculated, the radionuclides ensure the normal functioning of the complex in a negligible radiation risk range for the population (Radiation Safety Standards (RSS-99/2009)).

Lifetime attributable risk of radiation induced second primary cancer from scattering and scanning proton therapy – A model for out-of-field organs of paediatric patients with cranial cancer

Background and PurposeProton therapy (PT) can reduce side effects for paediatric cranial malignancies. Despite the high number of paediatric patients treated with PT, radiation induced risk factors for second primary cancer (SPC) in out-of-field organs are unknown. This study estimated lifetime attributable risk (LAR) of SPC as a function of age and sex for out-of-field organs following passive scattering and scanning beam PT in paediatric brain tumours. Materials and MethodsMeasured neutron dose equivalent spectra for scattered and scanning PT were sourced from literature. The physical distance of 12 measured organs from paediatric CT dataset-based phantoms (5, 9 and 13 years-of-age) were applied to Schneider et al.’s analytical model using MATLAB (R2020B) to calculate the organ-specific LAR of SPC. ResultsScanning beam PT demonstrated smaller LAR (per 10,000 person years) of SPC compared to scattering. This was prominent for more radiosensitive organs, including the lung (320 vs 50), breast (1000 vs 150) and thyroid (350 vs 75), but not for all (i.e., rectum and reproductive organs were <10). For most organs, LAR was highest for 5-year-old females (i.e., breast LAR was 1,000 higher than for 13-year-olds), however, outliers existed for distal organs (i.e., stomach and lung). ConclusionThere was large variation in LAR estimates of out-of-field organs based on measured neutron dose equivalents. Younger female cranial paediatric patients were found at higher risk compared to males, especially for passive scattering PT. Not all organs had improved LAR using scanning beam PT for younger age groups.

Соотношение радиационно-обусловленных потенциальных канцерогенных рисков ОЯТ реактора ВВЭР-1000 и РАО реактора БРЕСТ-1200 при выработке 1 ГВт х год электроэнергии. Часть 1. Радиологическая эквивалентность

The paper presents for the first-time comparison of radiation safety for the population between spent nuclear fuel (SNF) irradiated in water-water power reactor with thermal neutrons (WWER-1000) and radioactive wastes (RW) from lead cooled fast neutrons reactor (BREST-1200). The re-actors generate equal amount of electric power 1 GW per year. Composition and radiation param-eters of long-lived radiation wastes sent to disposal is reviewed. Potential biological hazards from SNF and RW for about 10,000-years disposal were estimated as effective doses (Sv). To assess potential radiation-induced carcinogenic risk as estimates of lifetime attributable risk (LAR) new ICRP methodology was used. New ICRP methodology was used as the basis for the computer code for the program “Radiological protection of the population” (ROZA-N) developed by the Proryv Project of the Rosatom State Corporation. The project was registered at the Unified Register of Russian Software in 2021 (registration number 2442). It was found that potential radiation-induced carcinogenic risk for the population associated with WWER-1000 reactor SNF was 132 times high-er than the risk associated with BREST-1200 reactor RW. Radiological equivalence of carcinogenic risks associated with SNF WWER-1000 and natural uranium material was proven to be achieved in about 15,600 years (significantly more than 10,000 years), the radiological equivalence of risks associated with RW BREST-1200, on the other hand, to be achieved only in 120 years.

Lifetime attributable cancer risk related to prevalent CT scan procedures in pediatric medical imaging centers

Purpose Evaluation of the organ dose in pediatric patients up to 15 years old and Estimation of lifetime attributable risk (LAR) of cancer incidence in pediatric computed tomography procedures. Materials and methods Data from 532 patients below 15 years old was collected and they were categorized into four age groups of <1, 1–5, 5–10, and 10–15 years old. NCICT software was used to calculate the organ dose, and LAR of cancer incidence has been estimated according to the BEIR VII report. Results The highest median dose in all age groups was related to eye lens (head scan), thyroid (chest scan), and colon (abdomen-pelvic scan). The highest average LAR of cancer incidence was observed for breast cancer and colon cancer following a chest CT scan of the youngest group (<1-year-olds) [68.23 per 100,000] and abdomen-pelvic scans of the oldest group (10- to 15-year-olds) [57.30 per 100,000]. Conclusion This study shows that the average LAR is higher in females and it decreases with age in both genders. Although CT scan has an indispensable application in diagnosis, the patient dose should be taken into account before any examination specifically in pediatric patients.

Assessment of the Effective Dose to the Human Body and Estimation of Lifetime Attributable Risk by CT Examination

Assessment of the Effective Dose to the Human Body and Estimation of Lifetime Attributable Risk by CT Examination

Assessment of computed tomography radiation doses for paediatric head and chest examinations using paediatric phantoms of three different ages

IntroductionWith the rapid development of computed tomography (CT) scanners, the assessment of the radiation dose received by the patient has become a heavily researched topic and may result in a reduction in radiation exposure risk. In this study, radiation doses were measured using three paediatric phantoms for head and chest CT examinations in Najran, Saudi Arabia. MethodsThirteen scanners were included in the study to estimate the CT radiation doses using three phantoms representing three age groups (1-, 5-, and 10-year-old patients). ResultsThe volume CT dose index (CTDIvol) estimated for each phantom ranged from 6.56 to 41.12 mGy and 0.292 to 11.10 mGy for the head and chest examinations, respectively. The estimation of lifetime attributable risk (LAR) indicated that the cancer risk could reach approximately 0.02–0.16% per 500 children undergoing head and chest CT examinations. ConclusionThe comparison with the published data of the European Commission (EC) and countries reported in this study revealed that the mean CTDIvol for the head examinations was within the recommended dose reference levels (DRLs). Meanwhile, chest results exceeded the international DRLs for the one-year-old phantoms, suggesting that optimisation work is required at a number of sites. Implications for practiceThe variation among CT doses reported in this study showed that substantial standardisation is needed.

ORGAN EQUIVALENT DOSE AND LIFETIME ATTRIBUTABLE RISK OF CANCER INCIDENCE AND MORTALITY ASSOCIATED WITH CARDIAC CT ANGIOGRAPHY.

The aim of this study is the calculation of equivalent organ dose and estimation of lifetime attributable risk (LAR) of cancer incidence and mortality related to cardiac computed tomography angiography (CCTA) because the use of CT angiography as a noninvasive diagnostic method has increased. The organ dose has been calculated by ImPACT software based on the volumetric CT dose index (CTDIvol), and LAR of cancer risk incidence and mortality from CCTA has estimated according to the BEIR VII report. The median value of the effective dose was 13.78±6.88mSv for both genders. In all scanners, the highest median value for LAR of cancer incidence in males and females for lung cancer was 44.20 and 109.17 per 100 000, respectively. And in infants was 5.89 and 12 for lung cancer in males and breast cancer in females, respectively. Also, the median value of LAR of all cancer incidence from single CCTA in adult patients for males and females was 122 and 238 cases, respectively. Maximum LAR of cancer mortality in adults for lung cancer was 40.28 and 91.84 and in pediatrics was 5.69 and 8.50 in males and females, respectively. Despite many benefits of CTA in the heart disease evaluation, according to a high radiation dose in CCTA, to reduce the cancer risk: CCTA should be used cautiously, especially for pediatric and females.

Occupational radiation exposure of health professionals and cancer risk assessment for Lithuanian nuclear medicine workers

BackgroundReconstruction and analysis of low doses received by the occupationally exposed medical radiation workers, especially nuclear medicine staff dealing with radioisotopes may significantly contribute to the understanding of radiation impact on individuals, assess and predict radiation related risks for the development of cancer or other specific diseases. MethodsA pool of 2059 annual effective doses corresponding to 272 job's positions occupied by nuclear medicine and radiology workers for a certain time period over 26 years in five Lithuanian hospitals was investigated in order to analyze the occupational exposure tendencies to medical staff. Requested data, measured in terms of whole body dose, personal dose equivalent Hp(10), was obtained from the National Register of Sources of Ionizing Radiation and Occupational Exposure. Considering that nuclear medicine staff is dealing with open sources/radioisotopes, doses to extremities, Hp(0.07), were measured using thermoluminescent dosimeters (TLD) of LiF:Mg, Ti type. Lifetime risk estimations for the development of specific cancer (thyroid cancer and leukemia) for exposed radiation workers were performed using risk models included in BEIR VII report (BEIR VII, 2006). The conservative assessment of the thyroid exposure was performed using RadRAT 4.1.1 tool. ResultsDoses to radiology technologists and radiology nurses were found to be highest over the years. However, their annual doses never exceeded dose limit of 20 mSv and were following the same decreasing tendency as the doses of other personnel. There was no increase of doses to nuclear medicine staff observed after installation of two new PET/CT machines, indicating increased radiation protection culture and application of relevant technical and protective measures by the staff. Measured fingertip doses were 2–3 times higher than the hand doses measured with TLD ring and were dependent on the type and frequency of the nuclear medicine examination procedure and on the type and activity of isotopes used for examination. ConclusionsFor the first time, retrospective dose evaluation for the cohort of medical radiation workers was performed in the country. It enabled estimation of lifetime attributable risk for the development of two cancer types: thyroid and leukemia cancer among occupationally exposed medical radiation staff. Projected risk was low, ~10−5, however it was found that the risk of thyroid cancer for female staff was 5.7 times higher than for the males. Obtained results will be used for the predictive assessment of possible radiation induced health effects to occupationally exposed medical radiation workers.

The Harms of Hematuria Evaluation: Modeling the Risk-Benefit of Using Split Bolus Computerized Tomography Urography to Reduce Radiation Exposure in a Theoretical Cohort.

Computerized tomography urography is used to evaluate patients with gross or microscopic hematuria. Computerized tomography urography is a high radiation dose scan and, thus, it confers a higher risk of secondary malignancy. A computerized tomography urography split bolus protocol reduces radiation exposure but it may reduce sensitivity. In this study we used a theoretical cohort of patients with hematuria in which to model the risk of missing malignancies against the benefit of averting secondary malignancies. We calculated the prevalence of renal cell carcinoma and upper tract urothelial carcinoma in patients with hematuria by pooled analysis of cohort studies, which in conjunction with split bolus sensitivity allows for the estimation of missed malignancies. The number of prevented secondary malignancies was calculated from lifetime attributable risk estimates. Sensitivity analyses were run to determine the minimum sensitivity required for a net population benefit. Estimates of split bolus computerized tomography urography sensitivity ranged from 80% to 100% (mean 95.2%). At the low estimate of 80% sensitivity split bolus computerized tomography urography was beneficial in men and women with microscopic hematuria at ages less than 50 and less than 60 years, respectively. An increase in sensitivity to 90% improved the benefit 1 decade in each gender, representing 68.8% of patients with microscopic hematuria. The overall population of patients with microscopic hematuria benefited from split bolus computerized tomography urography at 91.1% sensitivity. However, in patients with gross hematuria the threshold for an overall population benefit was high at 98.4% sensitivity. Exposure to ionizing radiation risks causing secondary malignancy. These data indicate that split bolus computerized tomography urography may be performed safely in 70% of the population of patients with microscopic hematuria. However, it is not currently advisable in patients with gross hematuria or in other patients at high risk.

Usefulness of cancer-free survival in estimating the lifetime attributable risk of cancer incidence from radiation exposure

Risk projection models estimating the lifetime cancer risk from radiation exposure are generally based on exposure dose, age at exposure, attained age, gender and study-population-specific factors such as baseline cancer risks and survival rates. Because such models have mostly been based on the Life Span Study cohort of Japanese atomic bomb survivors, the baseline risks and survival rates in the target population should be considered when applying the cancer risk. The survival function used in the risk projection models that are commonly used in the radiological protection field to estimate the cancer risk from medical or occupational exposure is based on all-cause mortality. Thus, it may not be accurate for estimating the lifetime risk of high-incidence but not life-threatening cancer with a long-term survival rate. Herein, we present the lifetime attributable risk (LAR) estimates of all solid cancers except thyroid cancer, thyroid cancer, and leukemia except chronic lymphocytic leukemia in South Korea for lifetime exposure to 1 mGy per year using the cancer-free survival function, as recently applied in the Fukushima health risk assessment by the World Health Organization. Compared with the estimates of LARs using an overall survival function solely based on all-cause mortality, the LARs of all solid cancers except thyroid cancer, and thyroid cancer evaluated using the cancer-free survival function, decreased by approximately 13% and 1% for men and 9% and 5% for women, respectively. The LAR of leukemia except chronic lymphocytic leukemia barely changed for either gender owing to the small absolute difference between its incidence and mortality. Given that many cancers have a high curative rate and low mortality rate, using a survival function solely based on all-cause mortality may cause an overestimation of the lifetime risk of cancer incidence. The lifetime fractional risk was robust against the choice of survival function.

Second cancer risk assessments after involved-site radiotherapy for mediastinal Hodgkin lymphoma.

This study was conducted to provide second cancer risk assessments attributable to involved-site radiotherapy (ISRT) of mediastinal Hodgkin lymphoma (HL) and to compare these risks with those from the conventional involved-field radiation therapy (IFRT). Both ISRT and IFRT plans were made for 11 patients (six females, five males) with HL in the region of mediastinum. All three-dimensional plans involved 6 MV photon beams and delivered 30 Gy to the target site. Differential dose-volume histograms were defined for the lung, female breast, and esophagus which were partly included within the planned treatment fields. The patient-specific organ equivalent dose (OED) and the relevant lifetime attributable risk (LAR) of developing malignancies in each of the above critical organs were determined with the aid of a mechanistic, plateau and bell-shaped models. The LAR estimates were compared with the baseline risks for unexposed people. The OED range of lung, breast, and esophagus calculated by the ISRT plans was 176.1-360.2, 19.5-124.1, and 42.6-157.7 cGy, respectively. The resultant LARs of developing lung and breast cancer as estimated by the three different models were at least 1.8 and 5.3 times lower than the baseline risks, respectively. The probability for the appearance of radiation-induced esophageal malignancies from ISRT in males was also up to 3.8 times smaller than the nominal incidence cancer rates. The corresponding probability in irradiated females exceeded the baseline risks. The estimated lifetime risks for lung and breast cancer induction due to ISRT were systematically and significantly lower than those from the IFRT irrespective of the model used for analysis (P < 0.05). No significant difference was found between the LARs for esophageal cancer development estimated by the ISRT and IFRT plans (P = 0.63). The presented second cancer risk data may be of value in the selection of the optimal radiotherapy technique for the management of mediastinal HL and in the subsequent follow-up of irradiated patients.

Survival adjusted cancer risks attributable to radiation exposure from cardiac catheterisations in children

ObjectivesTo estimate the risk of developing cancer in relation to the typical radiation doses received from a range of X-ray guided cardiac catheterisations in children, taking variable survival into account.MethodsRadiation...

Estimation of effective dose and lifetime attributable risk from multiple head CT scans in ventriculoperitoneal shunted children

PurposeThe purpose of this review is to determine the averaged effective dose and lifetime attributable risk factor from multiple head computed tomography (CT) dose data on children with ventriculoperitoneal shunts (VPS). Method and materialsA total of 422 paediatric head CT exams were found between October 2008 and January 2011 and retrospectively reviewed. The CT dose data was weighted with the latest IRCP 103 conversion factor to obtain the effective dose per study and the averaged effective dose was calculated. Estimates of the lifetime attributable risk were also calculated from the averaged effective dose using a conversion factor from the latest BEIR VII report. ResultsOur study found the highest effective doses in neonates and the lowest effective doses were observed in the 10–18 years age group. We estimated a 0.007% potential increase risk in neonates and 0.001% potential increased risk in teenagers over the base risk. ConclusionMultiple head CTs in children equates to a slight potential increase risk in lifetime attributable risk over the baseline risk for cancer, slightly higher in neonates relative to teenagers. The potential risks versus clinical benefit must be assessed.

Imaging Doses and Secondary Cancer Risk From Kilovoltage Cone-beam CT in Radiation Therapy

The authors assessed the radiation-induced cancer risk due to organ doses from kilovoltage (kV) cone beam computed tomography (CBCT), a verification technique in image-guided radiotherapy (IGRT). CBCTs were performed for three different treatment sites: the head and neck, chest, and pelvis. Using a glass dosimeter, primary doses versus depth were measured inside a homemade phantom, and organ doses were measured at various locations inside an anthropomorphic phantom. The excess relative risk (ERR), excess absolute risk (EAR), and lifetime attributable risk (LAR) for cancer induction were estimated using the BEIR VII models based on dose measurement. The average primary (i.e., in-field) doses at the center of the phantom for standard imaging options were 1.9, 5.1, and 16.7 cGy for the head and neck, chest, and pelvis, respectively. The average secondary dose per scan for the pelvis measured 20-50 cm from the isocenter and ranged from 0.67-0.02 cGy, whereas the secondary dose per scan for the head and neck ranged from 0.07-0.003 cGy, indicating that CBCT for treatment of the head and neck is associated with a smaller secondary radiation dose than CBCT for treatment of the pelvis. The estimation of LAR from CBCT in IGRT indicated that the lifetime cancer risk for major organs can reach approximately 400 per 10,000 persons if 30 CBCT scans are performed to position a patient during radiation treatment of the pelvis site.

Estimated additional lifetime risk of cancer attributable to diagnostic CT in a pediatric bone marrow transplant cohort: Experience at a single academic institution

Purpose: To determine the frequency of CT procedures in a cohort of bone marrow transplant patients and estimate the effective dose from each CT procedure as well as rough estimates of lifetime attributable risk (LAR) of cancer (both incidence and mortality). Background: Pediatric patients who undergo bone marrow transplant benefit greatly from the diagnostic power of computed tomography, but due to the need for frequent imaging, these patients are repeatedly exposed to the carcinogenic potential of ionizing radiation. Methods: CT Imaging and patient parameters were collected from a retrospective cohort of bone marrow transplant patients. Dosimetry was estimated as a function of age, dose length product (DLP), and scan region based on published DLP to effective dose tables. Lifetime attributable risk (LAR) of cancer as a function of age, gender, and organ specific dose was derived from BEIR VII phase 2 estimates. Results: 44 patients with bone marrow transplant were included and ranged in age from 7 months to 20 years (average age, 9 years). The average number of CT studies per patient was 3.2 over the 15 month period. The average effective dose for each study was 5.9 +/– 4.5 mSv. Cumulative effective dose to each patient was 20 +/– 32 mSv. It was estimated that in this cohort, the CT imaging performed over a 15-month period on a 64-slice scanner led to a lifetime additional risk of cancer incidence of 5 in 1000 and a lifetime additional risk of cancer mortality of 2 in 1000. Conclusion: Diagnostic CT is important in the assessment and management of ill patients following bone marrow transplant. The risk of ionizing radiation leading to additional development of cancer merits using as low a CT technique as reasonable to achieve a diagnostic study.

Estimates of lifetime attributable risk of cancer after a single radiation exposure from 64-slice computed tomographic coronary angiography

Estimates of lifetime attributable risk of cancer after a single radiation exposure from 64-slice computed tomographic coronary angiography

Estimates of lifetime attributable risk of cancer after a single radiation exposure from 64-slice computed tomographic coronary angiography

AimsTo estimate the life attributable risk (LAR) of cancer incidence over a wide range of dose radiation exposure and a large spectrum of possible diagnostic computed tomographic coronary angiography (CTCA)...