Preparing for radiation therapy starts well before your first treatment session. Most of the preparation happens in two phases: a planning appointment called a simulation, then a waiting period of one to two weeks while your care team designs your treatment plan. During that time, and depending on where on your body you’re being treated, there are specific things you can do to make the process smoother and more comfortable.
What Happens at the Simulation
Your first major appointment is the simulation, often called “SIM.” This is not a treatment session. It’s a planning visit where your team maps the exact area that will receive radiation. The appointment takes about an hour.
During the simulation, you’ll lie on a table and have a CT scan so your team can see the precise anatomy they need to target. If your treatment involves the head, neck, or brain, a custom-fit mask will be molded to your face to keep you still during future sessions. For other body areas, you might get a leg mold or body cradle. These devices feel snug but are designed to hold you in the exact same position every time you come in. Your skin will be marked with tiny dots of permanent ink, each about the size of a freckle, so your therapists can line you up accurately at every appointment. Some patients receive IV contrast dye during this scan.
After the simulation, your radiation oncology team spends one to two weeks using the CT images to build a custom treatment plan. You won’t have any appointments during this gap, which can feel like an anxious wait. Use that time to handle the practical preparations below.
Skin Care Before and During Treatment
Radiation can irritate skin in the treatment area, but starting a simple skin routine before your first session helps your skin hold up better. European radiation oncology guidelines recommend applying a basic, unscented moisturizer to the treatment area starting before treatment begins, not waiting until skin problems appear. Calendula cream in particular has been shown to reduce the severity of skin reactions.
For washing, use lukewarm water and a mild, fragrance-free, pH-neutral soap. Pat the treatment area dry gently rather than rubbing. You can use deodorant unless the skin in your treatment area is broken. Despite older advice to avoid all deodorants during radiation, current evidence shows that standard deodorants, including those with aluminum, don’t worsen skin reactions. That said, alcohol-free options are a reasonable choice if you want to minimize any extra irritation.
What to Wear to Appointments
Your clothing choices matter more than you might expect. You’ll need to expose the treatment area quickly at each session, and no metal can be near the beam. That means no zippers, underwire bras, buttons, body piercings, earrings, or jewelry in the treatment zone.
- Pelvis: Sweatpants, pajama bottoms, or loose skirts with elastic waistbands. No metal closures.
- Chest or abdomen: A loose T-shirt or top you can easily pull up during treatment.
- Head, neck, or brain: A T-shirt or button-down that’s easy to remove completely, since you’ll be wearing an immobilization mask.
Soft, breathable fabrics like cotton reduce friction against skin that may become sensitive as treatment progresses.
Dental Work for Head and Neck Radiation
If your radiation targets the head or neck area, you’ll need a dental evaluation before treatment can start. Radiation to the jaw changes blood flow to the bone permanently, which means dental infections or extractions after treatment carry a serious risk of a condition where the jawbone doesn’t heal properly.
Your dentist or oral surgeon will take a panoramic X-ray and assess every tooth that falls within the radiation field. Teeth with deep cavities, significant gum disease, failed root canals, chronic pain, or impacted wisdom teeth with any sign of problems will likely need to come out before radiation begins. Even teeth with large old fillings, fractures, or heavy wear may be extracted as a precaution if they sit in the high-dose zone. This can feel aggressive, but the goal is to eliminate any tooth that could become a problem later, since post-radiation extractions are far riskier.
After extractions, you need a minimum of 14 to 21 days of healing before radiation can start. Your radiation oncologist and dentist will coordinate this timeline, so raise any dental concerns as early as possible to avoid delays.
Bladder Prep for Pelvic Radiation
If you’re receiving radiation to the pelvis, your team will likely ask you to have a comfortably full bladder at each session. A full bladder pushes other organs away from the radiation field, protecting healthy tissue. This applies to both the simulation scan and every treatment after it.
The standard protocol is to empty your bladder, then drink 350 milliliters of water (roughly two small glasses) and hold it for 30 to 45 minutes. You’ll want to practice this at home starting as soon as you consent to treatment. If 350 milliliters is too uncomfortable, try reducing to 300 milliliters and work from there. The goal is finding an amount you can reliably hold for the full 45 minutes, because consistency matters more than maximum volume. Aim for 2 to 3 liters of fluid throughout the day, favoring water and non-caffeinated drinks.
Managing Anxiety and Claustrophobia
Lying perfectly still inside a mask or on an open table while a large machine rotates around you is not a casual experience. Anxiety is common, and it doesn’t mean something is wrong with you. About 70% of breast cancer patients in one survey reported negative feelings about the permanent tattoo marks alone, so the emotional weight of the whole process is real.
If you know you’re prone to claustrophobia, especially with the head and neck masks, tell your team early. A technique called systematic desensitization can help: you learn a relaxation method like deep breathing or guided imagery, then gradually expose yourself to the feared situation in small steps. You start with the least stressful version (maybe just looking at the mask) and work up to wearing it for the full duration. In clinical practice, patients who go through this process successfully complete their full course of treatment.
When there isn’t enough time for behavioral techniques alone, or if anxiety is severe, your doctor can prescribe a short-acting anti-anxiety medication to take before each session. This is a standard option, not a last resort. Some patients use medication for the first few sessions and then find they no longer need it once the routine feels familiar.
About the Tattoo Marks
The small permanent ink dots placed during simulation serve as alignment guides so your treatment hits the same spot every session. They’re typically the size of a pinpoint, made with a lancet and India ink. Most people end up with three to five dots.
If the idea of permanent marks bothers you, it’s worth asking your center about alternatives. Some facilities now use ultraviolet fluorescent ink that’s invisible under normal lighting but shows up under a black light in the treatment room. Others use semipermanent methods like henna ink or temporary tattoo seals, though these are less durable and may need reapplication. A newer approach called surface-guided radiation therapy uses cameras to match your body position without skin marks at all, though it isn’t available everywhere. Bring this up at your simulation appointment, because the options vary by facility.
Practical Things to Line Up in Advance
Radiation therapy typically means daily appointments, Monday through Friday, for several weeks. Each session is short (usually 15 to 30 minutes including setup), but the cumulative time commitment adds up. A few logistics worth sorting out before your first day:
- Transportation: You won’t be sedated, so you can drive yourself. But fatigue builds over the course of treatment, so having a backup driver or ride service for later weeks is smart.
- Schedule: During your simulation, the therapist will discuss available time slots. If your work or childcare schedule is tight, mention it early since the same time slot is yours for the entire course of treatment.
- Nutrition: There’s no general fasting requirement for radiation. For some abdominal or pelvic treatments, your team may give specific instructions about eating or drinking beforehand. Otherwise, eat normally and focus on staying well-hydrated.
- Comfort items: Some centers allow you to listen to music during treatment. Ask whether you can bring headphones or whether they have a speaker system in the room.
The first session often takes longer than subsequent ones because your team will verify everything lines up with the plan. After that, daily visits become routine quickly. Most of your time at each appointment is spent on setup and positioning. The machine itself delivers the radiation in just a few minutes, and you won’t feel anything during the beam.