Frequency of Portal Images Required to Enhance Quality Assurance for Breast Cancer Patients Treated With Radiotherapy

Currently in Canada, and at the Cross Cancer Institute, the treatment of many women with breast cancer involves radiotherapy (RT). There is a complex process which takes place in order to plan the radiation therapy before patients commence their treatment. In many circumstances the investigators use computerized technology to assist in planning their treatment. This allows more precision in delivering the treatment to the desired areas and avoiding areas of normal tissue. Once the planning process is completed, the investigators then place marks with a marker pen on the skin of the patient to outline the area where the radiation will be delivered. The investigators confirm that the correct area is being treated with an x-ray taken on the treatment unit while the patient is in the treatment position. This is called a port film or verification film. The investigators then compare this to what they set up with the computerized data. If all the information matches, the patient is then treated for the full course of radiation, with the assumption that all treatments are given in the correct position. No further routine checking is done. The standard at some radiotherapy centers is that the patient treatment position is verified weekly by a portal film. At the Cross Cancer Institute the investigators normally only do it once at the beginning of treatment. No information is available to confirm the necessity of doing more frequent verification films, but in view of the very complex nature of the investigators' treatment delivery, it may be necessary to confirm the accuracy of their treatment more often. Over the course of a 4-5 week treatment the investigators know that some patients may lose weight, some become more relaxed after a few days, and some have trouble with the movement in their shoulders; all of these factors influence the positioning of the patient. Measurements taken on the treatment unit often change during the course of a patient's treatment, but no further verification is performed to ensure that the treated area is still what was initially intended. It is important from a quality assurance standpoint to see if more frequent checking of the radiation treatment set-up is indicated.

Sex

All

Minimum age

18 Years