Deep inspiration breath-hold (DIBH) is a method of delivering

radiotherapy Radiation therapy or radiotherapy, often abbreviated RT, RTx, or XRT, is a therapy using ionizing radiation, generally provided as part of cancer treatment to control or kill malignant cells and normally delivered by a linear accelerator. Radia ...

while limiting

radiation exposure Radiation is a moving form of energy, classified into ionizing and non-ionizing type. Ionizing radiation is further categorized into electromagnetic radiation (without matter) and particulate radiation (with matter). Electromagnetic radiation con ...

to the heart and lungs. It is used primarily for treating left-sided

breast cancer Breast cancer is cancer that develops from breast tissue. Signs of breast cancer may include a lump in the breast, a change in breast shape, dimpling of the skin, milk rejection, fluid coming from the nipple, a newly inverted nipple, or a re ...

. The technique involves a patient holding their breath during treatment. In DIBH techniques, treatment is only delivered at certain points in the breathing cycle, where the patient holds their breath. Since the relative positions of organs in the chest naturally changes during breathing, this allows treatment to be delivered to the target (tumour) while other organs are in the optimal position to receive least dose.

Treatment Methods

In the DIBH technique, the patient is initially maintained at quiet tidal

breathing Breathing (or ventilation) is the process of moving air into and from the lungs to facilitate gas exchange with the internal environment, mostly to flush out carbon dioxide and bring in oxygen. All aerobic creatures need oxygen for cellular ...

(i.e. normal, relaxed breathing), followed by a deep inspiration, a deep expiration, a second deep inspiration, and breath-hold. At this point the patient is at approximately 100%

vital capacity Vital capacity (VC) is the maximum amount of air a person can inhale after a maximum exhalation. It is equal to the sum of inspiratory reserve volume, tidal volume, and expiratory reserve volume. It is approximately equal to Forced Vital Capacity ( ...

, and simulation, verification, and treatment take place during this phase of breath-holding. DIBH is performed with several tangential fields for left-sided breast cancer. A patient is instructed to hold the breath while viewing the breathing pattern and the breath-hold position through a head-mounted mirror, thereby ensuring reproducibility of the breath-hold position in each delivery. A pair of video goggles may also be used for monitoring the breathing cycle. Patients who cannot maintain DIBH can still benefit from lung tracking techniques, for example

4DCT Four-dimensional computed tomography (4DCT) is a type of CT scanning which records multiple images over time. It allows playback of the scan as a video, so that physiological processes can be observed and internal movement can be tracked. The nam ...

. There are two basic methods of performing DIBH: free-breathing breath-hold, and

spirometry Spirometry (meaning ''the measuring of breath'') is the most common of the pulmonary function tests (PFTs). It measures lung function, specifically the amount (volume) and/or speed (flow) of air that can be inhaled and exhaled. Spirometry is he ...

-monitored deep inspiration breath hold.

Free-breathing breath-hold

Free-breathing breath-hold, also known as real-time position management (RPM) DIBH utilises an infra-red camera and markers placed on the patient to track movement of their chest, and their breathing. Another device for DIBH is known as Abches that monitors the breathing pattern. With the Abches, a patient is instructed to hold the breath at a specified breathing position by viewing a breathing level indicator, thereby reproducing an identical breath-hold position.

Spirometry-monitored breath-hold

Spirometry based designs are known as active breathing coordinator (ABC) DIBH systems. ABC utilises a mouth piece for the patient which can be used to control the flow of air to provide more reproducible results.

Effectiveness

The DIBH technique provides an advantage to conventional free-breathing treatment by decreasing lung density, reducing normal safety margins, and enabling more accurate treatment. These improvements contribute to the effective exclusion of normal lung tissue from the high-dose region and permit the use of higher treatment doses without increased risks of

toxicity Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a subst ...

. Treatment of patients with the DIBH technique is feasible in a clinical setting. With this technique, consistent lung inflation levels are achieved in patients, as judged by both spirometry and verification films. Breathing-induced tumor motion is significantly reduced using DIBH compared to free breathing, enabling better target coverage.

Future research

There is currently no clear selection criteria to predict which patients will benefit most from the DIBH technique, other than left

breast The breast is one of two prominences located on the upper ventral region of a primate's torso. Both females and males develop breasts from the same embryological tissues. In females, it serves as the mammary gland, which produces and secret ...

laterality. There is evidence to suggest

parasagittal The sagittal plane (; also known as the longitudinal plane) is an anatomical plane that divides the body into right and left sections. It is perpendicular to the transverse and coronal planes. The plane may be in the center of the body and divid ...

cardiac contact distance is a promising metric for selection and should be assessed in all future DIBH planning studies.

References

{{Reflist Radiation therapy Radiation health effects Medical physics Radiobiology