October 13, 2020

Deep-Inspiration Breath-Hold: A Brief Introduction

Introduction

Deep-inspiration breath-hold (DIBH) is a radiation therapy motion management technique implemented in clinics to improve dose sparing to organs at risk (OARs) when treating breast cancer and other chest or upper abdominal tumors. The primary concept underlying DIBH is that the patient will inhale a deep breath and then hold it for a certain amount of time, during which time the dose is delivered as prescribed. The breath-hold fundamentally alters the thoracic anatomy so as to decrease the dose delivered to the lungs, liver, and heart during treatment of the breast.

Methods and Investigations

Typically one of two methods are used for DIBH: manual and computer-controlled. Manual DIBH is by far the most common, as the resource barrier-of-entry is much lower and is convenient for clinicians. Patients follow audio or visual instructions to breathe into the treatment position, with feedback provided for fine adjustments. In the artificial domain, breath-hold can be performed by physically closing the patient’s airway for a certain amount of time using vendor-supplied equipment. There are some drawbacks to DIBH: using DIBH increases the patient’s treatment time and requires well-trained and experienced therapists to administer treatment.

New strategies are being investigated with the potential to significantly increase breath-hold time, allowing for longer beam-on time for each breath hold, resulting in shorter total treatment time and improved patient comfort. In one of the researched methods, oxygen is administered to patients before treatment (preoxygenation) to allow healthy patients to hold their breath for up to five minutes at a time.

Parkes et al. tested the feasibility of multiple breath-holds and demonstrated that healthy participants could complete nine prolonged breath holds in one sitting, for a total combined time of 41 minutes. They showed that the beam-on time for a typical 65-minute treatment would decrease to 41 minutes. The authors created conservative thresholds for blood pressure and oxygen saturation levels to quantify adverse effects. No participant consistently hit either threshold, and most participants never reached either of them. The new strategy could enable shorter treatment times in abdominal and thoracic cases.

DIBH Survey Results

Even though the latest enhancements require further investigation before clinical implementation, DIBH remains a standard technique in many clinics. A survey was posted in July 2017 in the MedPhys listserv polling subscribers about what coaching method was used most commonly for DIBH in clinics. In the survey, the options given were verbal coaching, a visual system with goggles, a visual system with an in-room display, or other. The results of this survey showed that 60.61% of the 33 respondents used verbal coaching. Respondents chose verbal coaching for its ease of implementation and perceived effectiveness. However, they noted that it did not work well with patients that suffered from hearing loss or language barriers.

A second survey from August 2020 polled users about imaging schemes used in different departments in treating DIBH breast. The results revealed a lack of consensus, with clinicians not preferring one imaging protocol over another. In fact, the largest percentage of respondents chose “other” as a response, with varied write-ins: CBCT daily, daily MV/MV, daily MV and daily SGRT, etc. Of the available selections, the most common response given was weekly MV ports with daily SGRT, with just over 22% of the vote. In a follow up question included in this survey, inquiring about use of cine imaging, 94% of respondents said they do not use cine MV imaging to verify DIBH positioning. It stands to reason that imaging methods for DIBH breast are diverse, so it is necessary to choose what best suits the clinical workflow.

Conclusion

Despite the pros and cons of each technique, DIBH plays a critical role in the clinic. DIBH allows for dose sparing of critical organs, such as lungs, liver, and heart, especially during breast treatments. Maximizing tumor control while keeping dose to adjacent structures as low as possible, DIBH allows clinics to provide excellent patient care via a number of methods to fit their unique workflow.