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Preparing for CyberKnife Treatment 

This handout helps you prepare for your CyberKnife radiation treatment. Following these diet and prep instructions can help prevent gas, bloating, and constipation, making your treatment more effective and smoother.

 

Why is it important to follow these instructions?

Being well-prepared for your treatment can prevent delays. Gas and stool in your body can interfere with the treatment process. During treatment, you lie on a table while the machine aims a beam at you. If the machine detects gas or stool, it will stop and try again from a different angle. By following these instructions, you can help reduce these issues, ensuring your treatment goes smoothly and quickly. 

 

Prep Instructions 

Starting 2 Days Before Treatment 

  • Every Night at 6 PM:  

    • After dinner, take two Dulcolax (Bisacodyl) pills (5 mg each).  

    • Only do this on the nights before your treatment. 

 

Day of Treatment 

  • 2 Hours Before Leaving Home for Treatment:  

    • Use one saline enema. You can purchase this at your local pharmacy (Fleet’s enema or any generic brand).  

    • If you have kidney disease, use a mineral oil enema instead.  

    • Make sure you have enough time to arrive on time for your scheduled appointment.  

    • Important Note: Do this at least 1-2 hours before you leave your home. Do not do it right before leaving for your appointment.

        

  • Bring Gas-X (simethicone): 

    • Bring extra strength Gas-X (Simethicone) to your appointments.  

    • Our staff will tell you when to take it. 

  • Before Treatment:  

    • Drink 2 cups (16 oz.) of water about 15 minutes before your treatment to ensure a full bladder. 

  • Arrive on Time:  

    • Be at your appointment on time every day.  

 

Diet Instructions Starting 2 Days Before Treatment

The table below shows what you can eat and drink, and what you should avoid, starting 2 days before your treatment.  

Food Group  

Foods Allowed 

Gas Forming Foods to Avoid 

Beverages 

Water, regular or decaffeinated coffee, tea, and other non-carbonated drinks 

Carbonated drinks, alcoholic drinks, and beverages with sugar alcohols (like mannitol and sorbitol) 

Milk and Dairy 

Skim to 2% milk, soy or almond milk, yogurt, sherbet, puddings, cream, and all types of cheese 

Buttermilk  

 

 

Fruits 

Honeydew, lemons, limes, small oranges, papaya, passion fruit, pineapple, rhubarb, tangelos, and canned fruit in light syrup 

Apples, applesauce, apricots, avocado, bananas, cantaloupe, dried fruits, grape juice, mangos, peaches, pears, pear juice, plums, prunes, prune juice, and watermelon 

Vegetables 

Beets, carrots, green beans, lettuce, spinach, tomatoes, yellow squash, zucchini, white potatoes (mashed, baked, or boiled without the skin; potato chips or other snack chips), marinara sauce made without onions or garlic (onion and garlic powder are okay) 

Asparagus, artichokes, broccoli, Brussels sprouts, cabbage, cauliflower, celery, cucumbers, garlic, kohlrabi, onions, leeks, scallions, shallots, parsnips, peppers, radishes, rutabagas, sauerkraut, sweet potatoes, and turnips 

Legumes and Nuts 

Smooth peanut and other nut butters 

Baked beans, kidney beans, navy beans, lentils, dried peas, chickpeas, butter beans, and soybeans 

Breads and Starches 

White bread, biscuits, cornbread, English muffins, waffles, pancakes, instant oatmeal, dry cereals with less than 3g fiber, crackers, graham crackers, animal crackers, pretzels, rice cakes, white pastas, white rice, risotto, white flour tortillas 

Bran cereals, granola, shredded wheat, steel-cut oats, old fashioned rolled oats, whole grain breads with nuts and seeds, brown rice, wild rice, whole wheat and bean pastas, popcorn 

Meats, Fish, Poultry and Eggs 

Lean cuts of beef, pork, poultry, or fish that are baked, broiled, roasted, or grilled. Fresh sliced meats, eggs, or egg whites 

Fried meats, high fat processed and luncheon meats like bacon, sausages, hot dogs, and deli meats 

Fats 

Moderate amounts of butter, margarine, or salad dressing (1 serving = 2 tablespoons)  

Fried foods 

Dessert and Miscellaneous Foods 

Plain cookies, plain cakes without icing, pies made with allowed foods including gelatin, jams, jellies, honey, and molasses 

Foods containing sorbitol or other sugar alcohols (commonly found in processed foods like protein bars, sugar-free candies, and gum) 

 

Important Reminders 

  • Temporary Diet Changes: 

    • These diet changes are temporary. 

    • Start following them 2 days before your treatment and keep following them until your treatment is finished.  

    • You can go back to your regular diet once your treatment is done. Many foods that we recommend avoiding are very healthy. After your treatment, we encourage you to keep them in your diet.  

  • Drink Plenty of Fluids: 

    • Drink 6-8 cups of fluids daily, starting 2 days before your treatment. 

  • Meeting with a Registered Dietitian: 

    • After your treatment, you can meet with a Registered Dietitian (RD) for personalized nutrition advice.  

    • This can help improve your overall health, lower the risk of your disease coming back, and help prevent other health problems.  

    • If you would like to meet with an RD, ask your provider for a consult. 

 

Additional Tips 

  • Eat slowly and drink without using straws to avoid swallowing too much air. Eat smaller meals, and chew with your mouth closed.  

  • If you are lactose intolerant, avoid dairy products during treatment. You can try lower lactose foods like yogurt or lactose-free milk. 

  • Check for sugar alcohols in ingredients; they often end with “ol.” Examples include sorbitol, mannitol, xylitol, erythritol, maltitol, isomalt, and lactitol. 

  • If you already eat whole grains, you may continue. If not, do not start during treatment. 

  • Be mindful of portion sizes to avoid digestive issues. Soft, well-cooked textures may be easier to digest.  

  • Keep a food diary to track what you eat and any effects on your bowels, gas, and pain.  

 

Meal Ideas 

Everyone is different and has different dietary needs. Below are some meal ideas, but remember, this is just a sample. You can adjust to fit your needs better.  

Pair the meals below with allowed fruits, vegetables, milk, mashed or baked potatoes (without skin), toasted French bread, or white rice. 

 

Breakfast 

  • Scrambled eggs or egg whites 

  • White toast or English muffin with small amount of margarine, jam, jelly, or honey 

  • Orange juice or allowed fruit juice (no pulp) 

  • Cereal (less than 3 g fiber per serving) with milk or milk alternative 

  • Toasted bagel with cream cheese or smooth peanut butter 

  • Pancakes or waffles with margarine and syrup 

  • Yogurt or cottage cheese 

 

Lunch 

  • Sandwiches with lean fresh-sliced meat (e.g., roast beef, turkey, chicken, or ham), tuna fish, cheese (if tolerated), or peanut butter and jelly on bread without seeds and nut 

  • Soup like chicken noodle, tomato, or vegetable (with allowed vegetables) 

  • Chef salad with allowed vegetables, meat, and salad dressing                 

 

Dinner 

  • Lean meat, chicken, or fish that is baked, broiled, roasted, or grilled 

  • Pasta with meat sauce (made with allowed ingredients) 

  • Beef stew with allowed vegetables, potatoes, and carrots 

  • Salad with allowed ingredients and salad dressing

 

Snack Ideas 

  • Hard cheeses and white crackers 

  • Smooth peanut butter and jelly sandwich 

  • Smoothies with yogurt, milk, and allowed fruits 

  • String cheese 

  • Fresh fruit like orange slices or fruit cup with allowed fruits 

  • Pimento cheese and crackers 

  • Pretzels with smooth peanut butter or other smooth nut butters 

  • Protein bars (avoid high fiber bars and those with sugar alcohols) 

 
 
©2025 NYU Langone Health. All rights reserved. Reviewed for health literacy. This information is not intended as a substitute for professional medical care. Always follow your health care provider's instructions.
Created 6/2025