ESTRO 2024 - Abstract Book

S5595

RTT - Patient care, preparation, immobilisation and IGRT verification protocols

ESTRO 2024

Copenhagen University Hospital – Herlev and Gentofte, Department of Oncology, Copenhagen, Denmark

Purpose/Objective:

Air in the rectum can affect the location of the elective and treatment areas in both patients with rectal- and bladder cancer. If the air affects the rectum, the treatment area in patients with bladder cancer will be pushed out of the PTV T and the elective areas pushed out of PTV-E. for patients with anal cancer the elective treatment area is not within the PTV-E and/or the anal canal is not within the ITV-T. The purpose of this study was to create a workflow guide for management of air in the lower rectum and anal canal during online adaptive radiotherapy for patients with anal or bladder cancer.

Material/Methods:

If CBCT before the adaptive process displays a lot of air in the lower rectum/anal canal, which is pushing or expected to move and push the targets during the adaptive workflow and treatment, the patient must be vented. If the patient cannot pass wind naturally, a female Catheter (CH14 18 cm) will be placed rectally. It is not always possible to use female catheters. It depends on the location of the tumor (high/low), tumor size and fraction number, as well as the position of the air. It must not be too painful for the patient. There is no great risk associated with the use of a catheter if it does not hurt the patient. If it is possible to place a female catheter before the adaptation, it can with great advantage be left in place until the treatment is over, prohibiting air-build-up during the adaption process. Alternatively, the patient is sent to the bathroom using a laxative. Subsequently, a new CBCT is taken which is used in the adaptive workflow. If there is still a lot of air in the rectum, the adaptive process can still be started. However, an additional CBCT is taken after the adaptive process, before treatment, to check that the targets are within the PTV´s. After implementing online adaptive radiotherapy for cancers in the pelvis, the RTT´s discovered that patients with a lot of air situated in the lower rectum/anal canal will get a much better treatment if the air is removed prior to treatment. Usually this means, that the patient must be taken off the couch and sent to the toilet with an extra laxative, which meant that the treatment time was extended. The patients are informed about which foods and drinks can provoke flatulence. The presence of air in the intestines is unavoidable and very difficult to regulate. If the patients experience a lot of flatulence, they should try avoiding some types of vegetables, carbonated drinks and chewing gum. Despite these precautions air is often still seen in the treatment area. It is standard procedure to start the patient on daily laxatives to avoid obstipation and excessive formation of gas. However, this has proven not to be enough in some cases. Then we use our workflow guide. Figure 2 illustrates CBCT taken before and after catheter placement. Results:

Conclusion:

We have used our workflow guide (figure 1) with great success. By implementation of the catheter, it has become possible to ensure optimal quality control of the treatment and the treatment time is not unnecessarily extended. Figure 2 illustrates CBCT taken before and after catheter placement.