# Understanding Radiation Safety in Heart Imaging: A Patient's Guide

Radiation from heart imaging tests—including CT scans, X-rays, fluoroscopy, and nuclear scans—is a growing health consideration because it carries a small but real potential for increasing lifetime cancer risk. This article explains how doctors measure radiation dose, what the actual risks are for patients and staff, and the many safety techniques used to keep radiation "As Low As Reasonably Practicable" (ALARP). While no radiation exposure is completely without risk, modern heart imaging is carefully optimized so that the benefits of accurate diagnosis and life-saving procedures far outweigh the small potential for harm.

# Understanding Radiation Safety in Heart Imaging: A Patient's Guide

## Table of Contents

- Key Points
- Introduction: Why Radiation Safety Matters in Heart Care
- How Radiation Dose Is Measured
- Understanding the Risks of Ionising Radiation
- Radiation Protection: Principles and Regulations
- Safe Use of Fluoroscopy in Heart Procedures
- Safe Use of CT Scanning for the Heart
- Safe Use of Nuclear Imaging
- What This Means for Patients
- Study Limitations
- Recommendations for Patients
- Frequently Asked Questions
- Source Information

## Key Points

- A CTCA dose of 3.7 mSv carries an estimated added lifetime cancer risk of about 1 in 7,000 for a 50-year-old man and 1 in 2,900 for a 50-year-old woman.
- The linear no-threshold model assumes cancer risk increases linearly with radiation dose, with no threshold below which no risk exists.
- For CTCA, a conversion factor of 0.028 mSv/mGy·cm is more appropriate than the outdated 0.014 factor, which underestimates effective dose.
- Deterministic effects like skin erythema have threshold doses, while stochastic effects such as cancer have no threshold and their likelihood increases with dose.
- Staff radiation exposure is reduced by doubling distance from the source, using lead aprons and thyroid shields, and keeping the detector close to the patient.

## Introduction: Why Radiation Safety Matters in Heart Care

Exposure to ionising radiation is an important healthcare concern, primarily because of the potential increased lifetime risk of cancer. This matters both for **patients** who undergo diagnostic imaging or interventional procedures and for **staff** who perform them. Ionising radiation refers to radiation in the electromagnetic spectrum that has enough energy to remove electrons from an atom. For diagnostic imaging, this involves X-rays and gamma rays.

To put this in context, the UK average background radiation dose is **2.7 mSv per year**, and about **0.4 mSv (16%)** of that comes from diagnostic medical examinations. The use of medical imaging has grown dramatically. In the UK, the number of CT scans performed increased **five-fold between 1996/1997 and 2012/2013**. Similar trends appear worldwide:

- The USA has seen a **three-fold increase** in the annual number of nuclear medicine procedures.
- CT procedures in the USA increased **20-fold between 1985 and 2005**.
- Cardiac imaging and interventional procedures account for approximately **40% of the US cumulative effective dose** from medical imaging.

This growth means it is more important than ever for cardiology teams to understand how to use radiation safely—and for patients to understand what that means for them.

## How Radiation Dose Is Measured

The term "radiation dose" can refer to several different measurements depending on the imaging method used. Understanding these terms helps patients make sense of the numbers they may hear.

### Key Dose Parameters by Imaging Type

-
**Absorbed dose:** The amount of energy deposited in a material per unit mass. Units: Gray (Gy). 1 Gy = 1 joule per kilogram.
-
**Equivalent dose:** Absorbed dose multiplied by a weighting factor based on the type of radiation (X-rays and gamma rays have a weighting factor of 1). Units: Sievert (Sv).
-
**Effective dose:** A whole-body quantity based on absorbed organ doses, weighted according to how sensitive each organ is to radiation. Units: Sieverts (Sv).

For **fluoroscopy** (used in invasive coronary angiography and interventional procedures), key measures include:

-
**Air kerma:** Energy transferred per unit mass of air, measured with an ionisation chamber (Gray).
-
**Dose area product (DAP):** The product of the air kerma and the X-ray beam area (Gy·cm²).
-
**Peak skin dose:** The accumulated absorbed dose to the most irradiated area of skin (Gray).
-
**Fluoroscopy exposure time:** The cumulative time fluoroscopy is used (seconds or minutes).

For **CT scanning**, the relevant measurements include:

-
**CT dose index (CTDI):** The average absorbed dose from one axial CT scan (Gray).
-
**Weighted CTDI (CTDIw):** CTDI weighted across the field of view (one-third centre, two-thirds edge).
-
**Volume CTDI (CTDIvol):** CTDIw divided by pitch (the table movement per rotation divided by slice thickness).
-
**Dose length product (DLP):** CTDIvol multiplied by the total scan length (mGy·cm).

For **nuclear medicine**, radiation comes from radiopharmaceuticals that emit gamma rays or particles. Administered radioactivity is measured in **becquerels (Bq)**, which represents nuclear decays per second.

### Effective Dose and Conversion Factors

**Effective dose** is the most widely used measure when discussing radiation because it can be calculated for all imaging modalities and gives an overall indication of risk. However, it was originally designed for radiation protection in populations and only considers cancer risk. The **International Commission on Radiological Protection (ICRP)** has produced tissue weighting factors that reflect how sensitive different tissues are to the cancer-causing effects of radiation.

Tissue
Weighting Factor

Gonads
0.08

Bone marrow
0.12

Colon
0.12

Lung
0.12

Stomach
0.12

Breast
0.12

Remainder tissues*
0.12

Bladder
0.04

Oesophagus
0.04

Liver
0.04

Thyroid
0.04

Bone surface
0.01

Brain
0.01

Salivary glands
0.01

Skin
0.01

**The "remainder tissues" refers to the adrenals, extrathoracic region, gallbladder, heart, kidneys, oral mucosa, pancreas, prostate, small intestine, spleen, thymus, uterus, lymph nodes and muscle, which together are assigned a weighting factor of 0.12.*

These weighting factors are averages for all ages, genders and body sizes, and assume the risk is the same as if the absorbed dose were distributed uniformly throughout the body.

Effective dose is calculated by multiplying the average equivalent dose in each exposed tissue by its tissue weighting factor and summing these values over the whole body. This is usually done using **Monte Carlo simulation software**. A faster method multiplies a displayed dose indicator (such as DAP or DLP) by a conversion factor for the specific modality and body region being imaged.

For CT, the most widely used conversion factor is **0.014 mSv/mGy·cm**. However, this figure is based on out-of-date tissue weighting factors, was derived using old CT technology, and was designed for chest CT—which includes a different proportion of radiosensitive tissues compared with CT coronary angiography (CTCA). **This conversion factor therefore underestimates the true radiation dose.**

A study using computer models of patients scanned with two scanners from one manufacturer showed that **0.028 mSv/mGy·cm** is a more appropriate conversion factor for CTCA. Conveniently, effective dose values calculated with the old factor can simply be doubled. A recent phantom study found conversion factors range from **0.020 to 0.043 mSv/mGy·cm** depending on CT scanner type, protocol and tube voltage. The average was **0.026 mSv/mGy·cm**, which has been proposed as a more appropriate conversion factor for CTCA.

There are similar issues for invasive coronary angiography (ICA) and nuclear imaging. Ideally, the conversion factor for ICA would account for screening time at different projection angles, but in practice a single conversion factor based on the average for commonly used projections is used. Conversion factors for DAP in ICA range from **0.18 to 0.24 mSv/Gy·cm²**. In nuclear imaging, effective dose is calculated by multiplying the administered radiopharmaceutical activity by a tracer-specific conversion factor. Uncertainties arise from errors in measuring administered activity, differences in patient pharmacokinetics, and variations in body habitus.

The choice of conversion factor has important implications for quoted effective doses, so the factor used must always be stated. For an individual patient, uncertainties in effective dose may be as high as **±40%**.

### Typical Doses for Common Heart Procedures

Typical effective doses for common procedures vary widely due to differences in equipment, protocols and patient demographics. Here are the approximate doses for a typical adult patient:

Procedure
Effective Dose (mSv)

Chest X-ray
0.02

Coronary artery calcium score CT
1–3

Low-dose coronary artery calcium score CT*
0.2–0.4

CT coronary angiography (CTCA)
2–5

TAVI CT assessment (chest, abdomen and pelvis)
5–50

Invasive coronary angiography (ICA)
2–20

TAVI, transapical
12–23

TAVI, transfemoral
33–100

Diagnostic electrophysiology study
0.1–3

Radiofrequency arrhythmia ablation
1–25

SPECT: 99mTc-sestamibi, stress only, full dose
10

SPECT: rest and stress, half dose
6

SPECT: rest and stress, full dose
13

SPECT: 99mTc-tetrofosmin, rest and stress, half dose
6

SPECT: rest and stress, full dose
11

SPECT: 201Thallium, rest and stress, half dose
10.4

SPECT: rest and stress, full dose
21

PET: 13N-ammonia (rest or stress)
2

PET: 15O-water (rest or stress)
2

PET: 82Rubidium chloride
3

PET: 18F-FDG
5

PET: 18F-Sodium fluoride
4

**Using iterative reconstruction and tube voltage of 100 kV or below. If attenuation correction CT is performed in nuclear imaging, an additional ~0.5–2 mSv must be added.*

Further standardisation, audit and quality improvement are essential to reduce radiation dose and improve consistency between hospitals. Radiation doses are estimates, not precisely known values.

## Understanding the Risks of Ionising Radiation

Ionising radiation can harm biological tissues either by directly damaging molecules such as proteins or DNA, or through the secondary effects of free radicals generated by ionisation. The body has inbuilt DNA repair mechanisms that can mitigate these effects. In fact, studies have identified biochemical markers of DNA damage and repair after CTCA, ICA and single-photon emission CT (SPECT), but these markers return to normal background levels within **1 day**.

### Deterministic (Non-Stochastic) Effects

Deterministic effects—such as skin redness (erythema) and hair loss—have a **threshold level**. Below this level, they do not occur. Above it, the severity of the effect increases with increasing dose. It is rare for these levels to be exceeded during normal diagnostic imaging. However, patients undergoing lengthy interventional procedures with prolonged fluoroscopic imaging in one position may exceed the threshold for skin damage.

Deterministic Effect
Absorbed Dose Threshold (Gy)*

Skin erythema (redness)
3–6

Skin burns
5–10

Temporary hair loss
4

Sterility
3–6

Cataracts
0.5

**For acute exposures, the time to develop these effects varies from 1 week for skin changes to 20 years for cataract development.*

Recent epidemiological studies have shown that the threshold dose for **lens opacities (cataracts)** is lower than previously thought—at **0.5 Gy** for both acute and protracted exposures. This is of particular importance for interventional cardiologists and electrophysiologists, which is why lead eye protection is recommended.

### Stochastic (Random) Effects

Stochastic effects—such as the development of malignancy and germ cell mutations—do **not** have a threshold level and may occur at any radiation dose. Their likelihood (but not severity) increases with increasing absorbed dose. The **"linear no threshold" (LNT) model** is widely used to relate radiation dose to these risks. In this model, risk increases linearly with radiation dose, and there is no dose below which they cannot occur.

Evidence for stochastic effects at doses greater than **100 mSv** comes from epidemiological studies (such as survivors of atomic weapon explosions and radiation accidents) and animal models. However, limitations include the different types of radiation involved, variation in absorbed doses, differences between acute and protracted exposures, and the lack of evidence at doses below 100 mSv. The inherent delay between exposure and cancer development complicates matters further:

-
**Solid malignancies** typically have a latency period of **10–20 years**.
-
**Lymphoma or leukaemia** have a shorter latency of **2–5 years**.

The background risk of cancer in the UK is approximately **50% over a lifetime**. Therefore, assessing the effect of low-dose radiation requires very large epidemiological studies. The National Research Council **Biological Effects of Ionising Radiation (BEIR) VII** committee has produced models that estimate the potential lifetime attributable risk of cancer from medical radiation exposures.

The risk of malignancy is higher for younger patients and women. Using these models, the estimated additional lifetime risk of cancer from a CTCA with a dose of **3.7 mSv** would be approximately:

-
**1 in 7,000** for a 50-year-old man
-
**1 in 2,900** for a 50-year-old woman

As a rough estimate, the risk of fatal malignancy from radiation exposure can be calculated as **5% per Sv**, or **1 in 20,000 per mSv**. It has been estimated that **0.59% of cancers in the UK in 2010** were due to diagnostic radiation exposures. However, this must always be balanced against the clear health benefits of performing these tests.

## Radiation Protection: Principles and Regulations

The central principles of radiation protection for medical exposures are **justification**, **optimisation** and **limitation**.

-
**Justification** means the benefits of radiation exposure should sufficiently outweigh the risks. Appropriateness criteria and national guidelines help determine whether an imaging test or procedure is suitable for an individual patient. Individual patient factors must also be considered.
-
**Optimisation** means using the minimum amount of radiation needed to achieve an adequate diagnosis or successful procedure—this is the "As Low As Reasonably Practicable" (ALARP) principle.
-
**Limitation** means the effective dose to an individual should not exceed recommended dose limits.

In the UK, two key regulations govern radiation use:

1.
**Ionising Radiation Regulations 2017 (IRR)** — These aim to ensure that doses to staff and the public from workplace radiation use are kept as low as reasonably practicable. This is the duty of the employer. Doses are minimised using engineering controls, systems of work and personal protective equipment. IRR prescribes annual dose limits for individuals. Following ICRP recommendations, the annual dose limit to the lens of the eye has been **reduced from 150 mSv to 20 mSv per year** in the most recent update.
1.
**Ionising Radiation (Medical Exposure) Regulations 2017 (IR(ME)R)** — These cover the justification and optimisation of medical exposures. Key roles include the **employer** (sets entitlements), **referrer** (requests the investigation and provides enough information), **practitioner** (assesses whether the examination is justified and authorises it), and **operator** (carries out the practical aspects). IR(ME)R also includes requirements for training, quality assurance of procedures and equipment, optimisation of exposures, and notification requirements.

IR(ME)R established the requirement for **diagnostic reference levels (DRLs)**. DRLs are dose levels for typical examinations based on standard-sized patients (within a restricted weight range of **50–90 kg**). In the UK, DRLs are calculated as the rounded third quartile value of the distribution of dosimetric values for the examination. National DRLs are available for some common examinations—though notably, there is currently **no national DRL for CTCA**.

DRLs are not an "average" radiation dose and are not a dose limit. They serve as an indication of good practice to benchmark local practices. Individual exposures are not expected to consistently exceed DRLs under normal circumstances, but this must be weighed alongside clinical factors such as patient body habitus, procedural complexity and net patient benefit. Examples where DRLs may be exceeded include complex ICA for chronic total occlusion, or when the local population has a higher average body mass index than the restricted weight range used to calculate the DRL.

Procedure
DAP per exam (Gy·cm²)
Fluoroscopy Time per exam (min)

Coronary angiography
31
4.3

Coronary graft angiography
47
13

Percutaneous transluminal coronary angioplasty (single stent)
40
11.3

Pacemaker (permanent)
7
6

IR(ME)R also now requires employers to have a programme of radiation equipment quality assurance and to ensure patients are given information about the benefits and risks of an exposure before it happens. Additionally, the administration of radioactive substances is governed under IR(ME)R, with licence applications currently managed by the Department of Health and Social Care.

## Safe Use of Fluoroscopy in Heart Procedures

Fluoroscopy is used in invasive coronary angiography (ICA), percutaneous coronary intervention, device implantation and electrophysiology. Optimising radiation exposure during fluoroscopy minimises dose to both patients and staff through three avenues: hardware improvements, software improvements and good operator technique.

### Technology That Reduces Dose

- Automated exposure control
- Spectral beam shaping filters
- Pulsed fluoroscopy
- Flat panel detectors
- "Last image hold" feature
- Fluoro-loops and fluoro-save features

### Good Operator Technique

- Appropriate **collimation** (reducing the size of the primary X-ray beam)
- Minimising exposure time
- Keeping the detector **close to the patient**

- Viewing saved fluoro-loops rather than repeated screening
- Avoiding steep oblique fluoroscopic angles, which **increase radiation dose**

Real-time feedback to staff can help improve understanding of radiation dose, particularly for trainees.

### Staff Exposure During Fluoroscopy

Staff radiation exposure comes from the primary beam and **scattered radiation**. The **transradial approach** (access through the wrist) has a slightly increased operator radiation exposure compared with the **transfemoral approach** (access through the groin), because the operator is closer to the X-ray tube and ceiling-mounted shielding is less effective in this position. **Subclavian access** means an even closer operator position and therefore higher radiation dose.

The simplest way to reduce staff radiation dose is the **"inverse square law"**: doubling the distance between the operator and the radiation source reduces the dose by a factor of **four**.

Personal protective equipment includes lead-equivalent aprons, thyroid shields, glasses, hats, gloves and shin covers. At **80 kV**, a **0.35 mm lead-equivalent apron** transmits only **3.1%** of the radiation exposure. Aprons must fit well and close at the sides, since operators are often angled toward the X-ray tube. Lead aprons and eye protection should be checked annually for defects and stored carefully.

Room shielding includes ceiling-mounted shields, lead table skirts and patient drapes. Shielding in the walls and doors of the fluoroscopy room reduces dose to those outside the controlled area to well below the public dose limit. Extra care is needed during complex interventions, where prolonged screening and additional staff increase occupational exposures. Careful planning—such as assessing implantation angles on CT before transcatheter aortic valve implantation (TAVI) or using electroanatomical mapping for ablations—can reduce exposure times.

Staff dose monitoring uses passive or active personal dosimetry monitors for whole body, collar, lens or extremity dose. The average occupational whole body exposure for UK cardiologists in 2009/2010 was **0.12 mSv**. Interventional cardiologists and cardiac electrophysiologists can have exposures **two to three times higher** than diagnostic radiologists.

The health effects of this occupational exposure are uncertain. A study of **43,763 radiologists** and **64,990 psychiatrists** showed an increase in melanoma, non-Hodgkin's lymphoma and cerebrovascular disease among radiologists practising before 1940, but **no excess mortality** in those who started practising after 1940. Another study identified increased leukaemia mortality among men performing fluoroscopy-guided interventions who graduated before 1940, but no overall increase in mortality compared with psychiatrists.

## Safe Use of CT Scanning for the Heart

CT of the heart takes several forms, including non-contrast ECG-gated **coronary artery calcium score (CACS)**, contrast-enhanced ECG-gated **CT coronary angiography (CTCA)**, and CT imaging prior to TAVI. In the UK, the average patient dose for CTCA is **5.9 mSv** (209 mGy·cm, using a conversion factor of 0.028 mSv/mGy·cm).

CACS uses standardised acquisition parameters to provide consistent assessment of calcium, with a radiation dose of **1–3 mSv**. Low-dose CACS is possible (**0.2–0.4 mSv**) but may overestimate or underestimate calcium scores. CT for patients undergoing TAVI involves scanning the chest, abdomen and pelvis to assess the heart and vascular system; the dose is higher than CTCA because of faster heart rates and the larger scan range.

The dose for CTCA depends on patient factors such as **heart rate** and **body mass index**. The reason for the test also matters—for example, assessing coronary artery bypass grafts requires a larger scan range than assessing native coronary arteries.

Radiation dose reduction techniques for CTCA include:

- Prospective ECG-gating
- Reducing tube voltage and tube current
- Tube current modulation
- Minimising the scan range
- Iterative or model-based image reconstruction (which provides diagnostic quality images at lower doses)

Using state-of-the-art technology in patients with slow heart rates and low body mass index, average radiation doses for CTCA can be as low as **0.29 mSv**—remarkably close to the dose of a few chest X-rays.

## Safe Use of Nuclear Imaging

Nuclear techniques are the **most common form of cardiac imaging worldwide**. In the USA, cardiac nuclear imaging accounts for **26%** of all cardiac imaging. These tests involve injecting a radiopharmaceutical and measuring the gamma rays it emits.

Typical effective doses depend on the tracer used and the protocol. As shown in the table above, SPECT doses range from **6 mSv** (half-dose rest and stress protocols) to **21 mSv** (full-dose thallium rest and stress). PET doses are generally lower, ranging from **2 mSv** (13N-ammonia or 15O-water) to **5 mSv** (18F-FDG). If an attenuation correction CT is performed, an additional **0.5–2 mSv** must be added to these values.

These typical values are based on recommended tracer injected activity for standard patients. Optimisation of nuclear imaging involves choosing the lowest activity that still produces diagnostic-quality images, considering the patient's body habitus and the clinical question.

## What This Means for Patients

For patients, the key takeaway is that the radiation dose from a single diagnostic test is generally low, and the risk of harm is small compared with the benefit of getting an accurate diagnosis. For context, a CTCA at a typical dose of 3.7 mSv carries an estimated additional lifetime cancer risk of about **1 in 7,000** for a 50-year-old man and **1 in 2,900** for a 50-year-old woman—against a background lifetime cancer risk of approximately **50%**.

Some procedures carry higher doses than others. Complex interventional procedures such as TAVI (transfemoral) can deliver **33–100 mSv**, which is considerably higher than a standard CTCA. Patients undergoing such procedures should discuss the risks and benefits with their cardiologist, though these procedures are typically life-saving and the benefits far outweigh the risks.

For younger patients and women, the risks are relatively higher, and doctors take extra care to minimise radiation exposure whenever possible. The appropriateness criteria and national guidelines—which your doctor follows—are designed to ensure you only receive radiation when it is genuinely needed.

## Study Limitations

This educational review acknowledges several important limitations in the field of radiation safety in cardiology:

-
**Uncertainty in dose estimates:** For an individual patient, uncertainties in effective dose can be ±40%. Conversion factors vary by scanner type, protocol and tube voltage.
-
**Outdated conversion factors:** The widely used 0.014 mSv/mGy·cm CT conversion factor underestimates radiation dose and is based on old technology and tissue weighting factors.
-
**Lack of low-dose evidence:** The LNT model relies on evidence from doses above 100 mSv; there is limited direct evidence of cancer risk at the low doses used in diagnostic imaging.
-
**No national DRL for CTCA:** This limits benchmarking and standardisation of CTCA doses across UK centres.
-
**Occupational exposure data are mixed:** Studies of medical staff show no excess mortality in those who began practice after 1940, but long-term effects remain uncertain.

## Recommendations for Patients

If you are scheduled for a heart imaging test or procedure that involves radiation, here is what you should know and ask:

1.
**Ask why the test is needed.** Your doctor should be able to explain how the results will change your treatment. If a test is unlikely to change your management, it may be unnecessary.
1.
**Ask about alternatives.** For some questions, an ultrasound (echocardiogram) or MRI may provide the needed information without using radiation.
1.
**Tell your doctor about prior imaging.** If you have recently had CT scans or nuclear tests elsewhere, let your cardiology team know so they can avoid unnecessary repeat exposures.
1.
**Do not be afraid of necessary tests.** The risk from a single diagnostic test is very small compared with the risk of an undiagnosed or improperly treated heart condition. For example, a 50-year-old woman having a CTCA has a risk of around 1 in 2,900 of developing a radiation-related cancer—compared with a 50% lifetime background cancer risk.
1.
**Ask about low-dose protocols.** Many centres offer low-dose techniques (such as prospective ECG-gating or iterative reconstruction) that can substantially reduce radiation exposure while maintaining image quality.
1.
**For interventional procedures, discuss radiation with your interventional cardiologist.** Complex procedures can involve higher doses, and your team should be using ALARP principles to minimise exposure.
1.
**Staff protection matters for your safety too.** If you see staff wearing lead aprons, thyroid shields and eye protection during your procedure, that is a sign that the team is following best radiation safety practices—which also protects you.

## Frequently Asked Questions

### Is any radiation exposure completely safe?

The article states no radiation exposure is completely without risk. The linear no-threshold model assumes cancer risk increases linearly with dose and has no safe lower limit. However, benefits of accurate diagnosis and life-saving procedures usually far outweigh this small harm.

### What safety techniques are used to minimize radiation during heart procedures?

Teams follow the ALARP principle—keeping doses as low as reasonably practicable. Techniques include collimation, pulsed fluoroscopy, keeping the detector close to the patient, prospective ECG-gating, reducing tube voltage, and using iterative reconstruction. Staff use lead aprons, thyroid shields, and eye protection.

### Should I worry about having a necessary heart imaging test?

The risk from a single diagnostic test is generally low and small compared with the risk of an undiagnosed or improperly treated heart condition. Doctors use appropriateness criteria to ensure tests are justified. You can ask why the test is needed, about alternatives, and about low-dose protocols.

### How can I reduce radiation exposure from repeated heart tests?

Tell your doctor about recent CT or nuclear scans elsewhere to avoid unnecessary repeats. Ask if an ultrasound or MRI could answer the question without radiation. Also ask whether low-dose protocols are available, and whether the test will change your treatment.

### If my doctor recommends a heart CT scan or nuclear imaging test, when should I seek a second opinion about the radiation risk and possible alternatives?

A second opinion is worth considering if you are unsure whether a proposed heart imaging test—such as CT coronary angiography, a nuclear stress test, or a fluoroscopy-guided procedure—will change your treatment plan. Ultrasound (echocardiogram) or MRI can sometimes provide needed information without radiation. Tell your doctor about recent prior imaging to avoid unnecessary repeat exposures, and ask about low-dose protocols. Younger patients and women have relatively higher radiation risks, so they may particularly benefit from confirming the test is justified. Diagnostic Detectives Network provides independent expert second opinions.

## Source Information

**Original article title:** Using radiation safely in cardiology

**Authors:** Michelle Claire Williams, Christina Stewart, Nicholas W Weir, David E Newby

**Publication:** Heart (Education in Heart), 2019;105:798–806. Published online 18 February 2019.


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