Challenges of maintaining breath-hold conformity for breast patients while using the deep inspiration breath-hold technique

Deep inspiration breath-hold (DIBH) is used for whole breast radiotherapy, as a means of providing better dose homogeneity. This can be achieved by lower doses to the organs at risk, less patient movement and better set up. Most patients offered DIBH treatment are left-sided breast cancer, or ductal carcinoma in situ (DCIS) patients, due to the proximity of the heart to the chest wall so it is nearer the radiation field. However, if lung sparing is essential for the patient, DIBH offers a solution for right-sided breast cancer patients also. St Luke’s Cancer Centre at Royal Surrey County Hospital introduced a DIBH service in June 2012 for left-sided breast cancer patients. This service was initially introduced at a low level, with the increase in capacity over the course of 18 months achieving a service roll out to all left-sided breast patients, and selected right-sided breast patients. The Varian Real-time Position Management (RPM) system is used in the GE computed tomography (CT) scanner, and on the Varian Linacs. The marker box is placed horizontally onto the patient’s chest. This permits the in-room camera to detect the reflective markers. An assessment of the patient’s ability to hold their breath must be taken at the CT scanning appointment. Several practice sessions are performed before the DIBH CT scan is acquired to ensure that the patient can maintain a reproducible and constant deep inspiration breath-hold for the duration of the scan and for treatment, and is comfortable with the requirements. The patient must be able to take regular breath-holds, each being for a minimum of 15 seconds. It is also worth noting that the threshold (amplitude of the breathing trace) of the breath-hold should be assessed at this point to ensure the breath is deep enough to ensure reproducibility at treatment. Once the patient is comfortable with this procedure the DIBH scan is performed during a single breath-hold. To align the patient for treatment they are required to be in breath-hold. Once treatment commences, the linac will only deliver radiation when the marker box is detected in the breath threshold window as defined during the CT appointment using the RPM system.