A Computed Tomography (CT) scan uses a series of X-ray images taken from different angles to create detailed cross-sectional pictures of the body. These internal views help physicians diagnose various conditions, requiring clear, unobstructed data acquisition for accuracy. Therefore, the general rule is that any bra containing metal, such as an underwire, hooks, or adjusters, must be removed or replaced before the scan. The presence of dense materials like metal compromises the diagnostic quality of the resulting images.
The Problem: Interference from Metal Components
Metal components in clothing, including the hooks and underwires found in most bras, interact intensely with the X-ray beam used in CT scanning. This interaction leads to “metallic artifacts,” which appear as streaks, dark bands, or bright spots on the final image. Because metal is significantly denser than biological tissue, it strongly absorbs and scatters the X-rays passing through the body.
The resulting image degradation is caused by two effects: beam hardening and scattering. Beam hardening occurs when metal filters out lower-energy X-rays, leaving a “harder” beam that produces dark streaks. Scattering deflects the X-rays, leading to signal loss and further distortion radiating from the metallic object.
Even small pieces of metal, such as tiny eyelets or plastic-coated wires, can generate these artifacts. The streaking from these dense objects can obscure surrounding soft tissues, including lymph nodes, blood vessels, or small tumors. If artifacts cover the area of medical interest, the radiologist cannot accurately interpret the scan, potentially leading to a missed or incorrect diagnosis.
Location Matters: When Removal is Mandatory vs. Optional
The necessity of removing a bra depends directly on the anatomical area being examined. If the scan focuses on the chest (thorax), abdomen, or pelvis, bra removal is mandatory. This prevents metallic artifacts from obscuring organs within the field of view (FOV). Since an underwire bra often extends into the upper abdomen, its components could interfere with images of the heart, lungs, liver, or stomach.
If the CT scan targets areas far from the torso, such as the head, sinuses, or an extremity like the ankle, wearing a bra with metal components is often permissible. In these cases, the metal is outside the FOV and will not interfere with the X-ray data. The general rule is that anything falling within the path of the X-ray beam must be removed.
Acceptable Alternatives and Preparation
Patients who prefer to wear something other than a standard hospital gown have several non-metallic options. The most common alternative is a soft-cup sports bra or a bralette that contains no metal, plastic, or high-density material in the straps, adjusters, or closure. Patients should contact the imaging facility beforehand to confirm their specific policy regarding personal clothing.
Preparation should focus on comfort and ease of removal. Patients should arrive in loose-fitting, comfortable clothing without zippers, snaps, or metallic embellishments. Even if a non-metallic bra is worn, the facility may ask the patient to change into a medical gown to ensure a metal-free environment. Communicating with the technologist about any non-removable metallic implants or clothing concerns can streamline the process.