-- Radiologist talks about pelvic tumor radiotherapy
Chaoyue Liu, Department of Radiation Therapy, Characteristic Medical Center (formerly 306 Hospital).
Edited by Liu Yan/Cui Yan, Medical Science Popularization Center
Radiotherapy is an extremely important part of the cancer treatment process, about 70% of cancer patients will receive radiotherapy during treatment, and about 80% of pelvic cancer patients need radiotherapy at different stages of the disease. In order to be able to target pelvic tumors with more precise radiotherapy, it is usually necessary for patients to hold urine before positioning CT scan and before radiotherapy. Before they come for treatment every day, the doctor asks, "Did you hold your urine today?" Is the urine output up to standard? Behind the seemingly strange problem, it is actually the doctor who is escorting this part of the "special" patients.
Which patients with pelvic tumors need to hold urine during radiotherapy?
Rectal cancer, cervical cancer, endometrial cancer, prostate cancer, bladder cancer, and even secondary pelvic tumors, such as pelvic metastasis of lung cancer, etc., such pelvic tumors patients usually need to hold urine during CT scan and radiotherapy in order to reduce the radiation dose of the bladder and intestines and reduce the toxic side effects of radiotherapy during radiotherapy.
The purpose of holding urine
(1) Ensure the accuracy of the treatment position. During radiation therapy, the position needs to be kept as close as possible to the initial positioning. Then, maintaining the same amount of urine as when initially positioning can ensure that the various organs in the pelvis are in the same position, thus ensuring the accuracy of radiotherapy.
(2) Protect normal tissues. During radiotherapy, although we try to avoid irradiation to normal tissues, some tissues that are too close to the lesion or are very sensitive to radiation can still cause damage to these tissues. For example, the intestinal tract is sensitive to radiation, and intestinal damage after exposure is a common toxic side effect. After holding urine, the volume of the bladder will become larger, like a "water ball", not only the irradiated volume of the bladder itself will be reduced, but also the bladder filling can squeeze the intestine away from the irradiation area, thereby reducing the toxic side effects of the intestine.
Consequences of not holding urine
In pelvic radiotherapy that requires urine holding, if you do not hold urine or do not hold urine properly, the irradiated dose of the bladder and intestine will increase significantly, and there may be acute and chronic cystitis symptoms such as frequent urination, urgency, painful urination, or even hematuria, bladder contracture, diarrhea, changes in bowel habits, even blood in the stool, intestinal stricture and other acute and chronic radiation enteritis symptoms, and even need to undergo surgical treatment in severe cases.
Correct way to hold urine
The requirement of radiotherapy positioning is that the bladder needs to be filled to 150~300 ml, which is an abstract number, if there is a bladder volume measuring instrument to monitor the best, if not, it depends on the patient's own feelings.
Under normal circumstances, when the bladder accumulates close to 200 ml of urine, there is a strong urge to go to the toilet when the urine is close to 400 ml, and there will be pain and even urinary incontinence when the urine is close to 400 ml. Therefore, we ask patients to empty their urine and urine 1 hour before positioning or radiotherapy, and drink a certain amount of 500~1000ml of water in a short period of time (within 10 minutes) according to their personal conditions, remembering that it is plain water, not tea water, juice, or drink.
After drinking water, when you feel the urge to urinate, you can do CT positioning or radiotherapy. Because it takes about 10 minutes to undergo radiotherapy, don't hold back the urge to go to the toilet and leave no room for time. Write down the amount of water you drink and the amount of time you feel like urinating, and repeat the procedure before each treatment.
In the actual treatment, because different patients have different physical conditions, there is no unified method of holding urine, resulting in patients often holding too much or too little. Here are some small methods for everyone, when you hold too little urine, you can drink more water and walk around, which is conducive to the rapid entry of urine into the bladder; When holding urine too much, if the body can control urination, you can make a graduated disposable cup by yourself to control the volume of urination and prevent multiple urination.
In the middle and late stages of treatment, it can become difficult to hold urine, so it is recommended that patients who hold urine should find their own urination pattern in the early stage of treatment. How much water do you drink after emptying your bladder once? How long do you have to wait to urinate? Everyone should pay attention to these details in order to hold urine more easily in the later stage.
(The picture comes from the Internet)