A method for calculating effective lifetime risk of radiation-induced cancer from screening mammography

Previous studies on lifetime cancer risks from radiation at cardiac CT are based on extrapolation of data unrelated to medical imaging and on presumptive scan protocols but not on actual patient cohorts. We aimed to determine the realistic risk of radiation induced cancer based on a real-life clinical patient population undergoing cardiac CT. We studied 104 consecutive patients undergoing 64-slice cardiac CT (Siemens). Data were obtained on patient demographics (sex, age, weight) as well as CT technique (kV, mAs, scan length, DLP) which were used to determine median values and the 10th and 90th percentiles. Organ dose estimates were obtained using the ImPACT dosimetry spreadsheet. Organ doses were converted into patient lifetime risk of developing radiation induced fatal and non-fatal cancer using the BEIR VII approach. Patient cancer risks were adjusted taking into account patient sex, age and weight, the latter being an often neglected factor influencing radiation risk. The majority of patients (62%) were males, with a median patient age of 59 years (41–72) and a median weight of 92 kg (69–116). All scans were performed at 120 kV, and the median DLP was 1124 mGy-cm (940–1500). In normal sized patients, the organs receiving the highest radiation doses were the lung (76 mGy) and the female breasts (92 mGy). The average patient lifetime risk for developing a radiation induced cancer was 0.12%, of which 90% would be fatal. Approximately 85% of the radiation risk arises from the irradiation of the lung. Patients with an age and weight at the 10th percentile, who receive a DLP at the 90th percentile would have a cancer risk double the average value. In a typical clinical population undergoing cardiac CT patients are predominantly male, heavier set, and in their 5th–7th decade of life. In such a patient population the realistic risk of radiation induced cancer from cardiac CT is 0.12%, with the risk to the most sensitive patients being about twice this value. Thus, in a real-life clinical patient cohort the realistic risk of radiation induced cancer from cardiac CT is substantially lower than previously reported for general populations. Appropriate patient selection and indication remain the most important means for radiation protection.

Download Full-text

Breast-iRRISC: a novel model for predicting the individualised lifetime risk of radiation-induced breast cancer from a single screening event

British Journal of Radiology ◽

10.1259/bjr.20200734 ◽

2021 ◽

Vol 94 (1117) ◽

pp. 20200734

Author(s):

Sahand Hooshmand ◽

Warren M. Reed ◽

Mo’ayyad E. Suleiman ◽

Patrick C. Brennan

Keyword(s):

Breast Cancer ◽

Risk Model ◽

Clinical Decision ◽

Screening Mammography ◽

Lifetime Risk ◽

Total Risk ◽

Individual Level ◽

Cancer Breast ◽

Radiation Induced ◽

Mammographic Examination

Objectives: This work establishes the prototype of a new innovative risk model that aims to evaluate the total risk involved with screening mammography for each individual female. This has been specifically designed to accommodate any combination of lifetime screening regimes, using only the information gathered from a single mammographic examination. Methods: This model prototype was developed with the aid of a large dataset of images from the Cancer Institute New South Wales (CINSW) with over 30,000 images from over 7000 examinations. Each examination is derived from a separate female. Results: This prototype which we have called Breast Individualised Risk of Radiation-Induced Screening Cancer (Breast-iRRISC) is a novel tool for the assessment of the lifetime risk involved with screening mammography. The results demonstrate the applicability of this approach to the various screening regimes utilised around the globe, in addition to the personalised screening frequency patterns females have undergone and are likely to receive in the future. Conclusions: This unique tailored approach to risk assessment will further empower females and clinicians towards a more informed clinical decision process regarding future imaging pathways. It will also inform health policy decisions regarding alternate screening durations and intervals. Advances in knowledge: Breast-iRRISC is a novel tool that provides females, clinicians and health policymakers around the globe with the ability to quantify the lifetime risk of radiation-induced breast cancer from screening mammography on an individual level from a single exposure.

Download Full-text

Determine Cumulative Radiation Dose and Lifetime Cancer Risk in Marfan Syndrome Patients Who Underwent Computed Tomography Angiography of the Aorta in Northeast Thailand: A 5-Year Retrospective Cohort Study

Tomography ◽

10.3390/tomography8010010 ◽

2022 ◽

Vol 8 (1) ◽

pp. 120-130

Author(s):

Narumol Chaosuwannakit ◽

Phatraporn Aupongkaroon ◽

Pattarapong Makarawate

Keyword(s):

Computed Tomography ◽

Radiation Dose ◽

Cancer Risk ◽

Lifetime Risk ◽

Surveillance Imaging ◽

Radiation Induced Cancer ◽

Cumulative Radiation Dose ◽

Radiation Induced ◽

The Mean ◽

Risk Of Cancer

Objective: To evaluate computed tomography angiography (CTA) data focusing on radiation dose parameters in Thais with Marfan syndrome (MFS) and estimate the distribution of cumulative radiation exposure from CTA surveillance and the risk of cancers. Methods: Between 1st January 2015 and 31st December 2020, we retrospectively evaluated the cumulative CTA radiation doses of MFS patients who underwent CTA at Khon Kaen University Hospital, a leading teaching hospital and advanced tertiary care institution in northeastern Thailand. We utilized the Radiation Risk Assessment Tool (RadRAT) established at the National Cancer Institute in Bethesda, Maryland, to evaluate the risk of cancer-related CTA radiation. Results: The study recruited 29 adult MFS patients who had CTA of the aorta during a 5-year study period with 89 CTA studies. The mean cumulative CTDI vol is 21.5 ± 14.68 mGy, mean cumulative DLP is 682.2 ± 466.7 mGy.cm, the mean baseline future risk for all cancer is 26,134 ± 7601 per 100,000, and the excess lifetime risk for all cancer is 2080.3 ± 1330 per 100,000. The excess lifetime risk of radiation-induced cancer associated with the CTA surveillance study is significantly lower than the risk of aortic dissection or rupture and lower than the baseline future cancer risk. Conclusions: We attempted to quantify the radiation-induced cancer risk from CTA surveillance imaging performed for MFS patients in this study, with all patients receiving a low-risk cumulative radiation dose (less than 1 Gy) and all patients having a low excessive lifetime risk of cancer as a result of CTA. The risk–benefit decision must be made at the point of care, and it entails balancing the benefits of surveillance imaging in anticipating rupture and providing practical, safe treatment, therefore avoiding morbidity and mortality.

Download Full-text

Estimated Effective Lifetime Risks of Radiation-Induced Thyroid Cancer in Computed Tomography (CT) Brain Examination

Sains Malaysiana ◽

10.17576/jsm-2021-5011-20 ◽

2021 ◽

Vol 50 (11) ◽

pp. 3365-3372

Author(s):

Rekha Ganesan ◽

Muhammad Ikhmal Naim Mohd Hilal ◽

Iza Nurzawani Che Isa ◽

Norhashimah Norsuddin ◽

Khadijah Mohd Nassir ◽

...

Keyword(s):

Computed Tomography ◽

Thyroid Cancer ◽

Biological Effects ◽

Lifetime Risk ◽

Effective Lifetime ◽

Multiple Exposures ◽

Percentage Difference ◽

Radiation Induced ◽

Radiosensitive Organs ◽

Risk Of Cancer

Thyroid is one of the most radiosensitive organs in the human body. Although the scanning range of brain computed tomography (CT) does not include lower neck region, there is possibility for thyroid to be irradiated due to scattered radiation because of its location near to the external beam collimation. The objective of this study was to evaluate effective lifetime risk of radiation-induced thyroid cancer in young adults following brain CT examination. A total of 306 patient data within the age range between 18 and 39 years old were retrospectively analysed. Absorbed dose of the thyroid organ was obtained through the input of data using WAZA- ARI v2. Effective lifetime risk was calculated by multiplying equivalent dose of the thyroid organ with the lifetime attributable cancer risk adapted from Biological Effects in Ionising Radiation (BEIR) Report V11. The effective lifetime risks were recorded as 0.45 ± 0.70 per 100 000 and 0.93 ± 1.52 per 100 000 for single and multiple exposures, respectively. In terms of gender, woman data (0.99 ± 0.76; 1.95 ± 2.15) were found higher as compared to man data (0.13 ± 0.39; 0.35 ± 0.45) for both single and multiple exposure. The percentage difference of effective lifetime risks between single and multiple exposures was up to 107%. The effective lifetime risk noted in this study may be low, however, the long-term risk of cancer development should be considered. This study serves as preliminary reference when revising clinical protocol especially in those involving repeated exposures in young adult patients. Future study should include other radiosensitive organs exploring the effective lifetime risk of radiation induced cancer following CT procedure.

Download Full-text