Investigating the Improvement in 4D CT Images Using AV Biofeedback
Condition: Cancer of the Lung; Abdominal Cancer
MeSH terms: Lung Neoplasms
Study type: Observational

Summary: 
      This study will look at how tumors in the chest and abdomen move when you breathe. Your
      doctors are studying if extra 4D CT scans and instructions on how to breathe can help predict
      this type of movement and improve the accuracy of radiation treatment. 4D CT scans are
      approved by the FDA. A 4D CT scan is different from a regular CT because it moves slower and
      takes more pictures. It takes pictures of the way your body moves when you breathe. This
      gives doctors more pictures of your body so that they can match your pictures to the way you
      breathe.

      In this study, instructions on how to breathe will be visual and audio. Visual instructions
      will be given to you on a computer screen. You will hear audio instructions through a
      speaker.
    

Detailed description: 
      JUSTIFICATION Among the various sites affected by cancer, statistics show that lung cancer is
      the leading cause of death among both men and women. One major reason for this is that the
      treatment of lung cancer has not improved drastically in the past few years. Lung tumors are
      also potentially difficult to treat with radiation therapy due the patients' respiration
      motion causing the tumor to be mobile.

      A1) Detrimental effects of respiration motion Respiration motion affects all tumor sites in
      the thorax and abdomen, although the disease of most prevalence and relevance for
      radiotherapy is lung cancer. Many studies have been performed to study lung-tumor motion and
      methods to compensate for this motion during radiation treatment imaging, planning and
      delivery. The significance of the respiration motion compensation techniques is to reduce the
      mobility of the tumors and thereby reduce the dose to the surrounding normal structures. If
      no motion compensation methods are used then a margin must be added to ensure adequate
      coverage of the tumor. Large margins results in radiation delivered to a larger volume of
      critical structures.

      A2) Compensation techniques Methods that reduce respiration induced intrafraction motion
      include active breathing control, voluntary breath-hold, deep inspiration breath-hold,
      respiratory gated techniques, and 4D or tumor-tracking techniques.1-6 Active breathing
      control and the deep inspiration breath hold involves the patient holding their breath. While
      these may improve the reproducibility of the position of the tumor within the lung, it is not
      feasible for all patients especially those that have a compromised respiratory function.
      Respiratory gating techniques involves turning on the beam during only a small window of the
      respiratory cycle. Thus respiratory gating reduces the intrafraction motion but does not
      totally eliminate it. During respiratory gating, since the beam is turned on and off based on
      the respiration signal, the treatment time may increase up to 35-40% compared to a regular
      treatment. Since the patient has to spend more time on the table, this could introduce more
      errors due to patient movement on the table. 4D or tumor tracking techniques has it own share
      of issues as is discussed in the following paragraph.

      A3) During 4D radiotherapy (4DRT) delivery the tumor is continuously tracked with the
      radiation beam as they move throughout the respiratory cycle. The benefits of 4DRT are a
      reduction in dose to the healthy lung tissue and/or an increase in dose to the tumor. The
      gains from 4DRT are clinically measurable, though much development is needed in the various
      steps of 4DRT i.e. CT image acquisition, planning and delivery.

      During 4D CT image acquisition, images are acquired during different respiration states of
      normal breathing.7-9 The quality of images acquired by using the 4D CT image acquisition is
      limited by patients respiration pattern. Since the images are sorted based on the patients
      respiration motion, any change in pattern could lead to the images being sorted to a
      different part of respiration. This effect is reflected as an artifact on the CT image.

      Target volumes along with respiration motion can be determined by contouring the target in
      the various respiratory states thus obtaining a volume that encompasses an entire breathing
      cycle. The efficacy and accuracy of 4D CT will be maximized when patients breathe
      reproducibly. However it is well-known that respiration motion varies not only from one day
      to the next but also during one fraction.

      A4) Effect of irregular breathing For 4D CT, minimizing the variation of patient breathing
      within a treatment fraction and from fraction to fraction, i.e., increasing the
      reproducibility of patient breathing, is important. Large variation in patient respiration
      motion and irregular breathing lead to artifacts in the CT images as shown in. However,
      respiration motion amplitude and period vary with time and from patient to patient because of
      various anatomic and physiologic factors.

      A5) Possible solutions Biofeedback/coaching techniques are being increasingly embedded in the
      behavioral treatment of patients with lung disease such as chronic obstructive pulmonary
      disease, asthma, and cystic fibrosis. For respiratory gating, several studies suggest that
      verbal prompts improve respiration reproducibility. Kini et al.12 concluded that audio
      prompts improve the stability of respiration frequency of the patient but does not maintain
      the range of respiratory motion, whereas visual prompts control only the regularity of the
      displacement and the frequency is not reproducible. Based on the results of Kini et al.12,
      combined audio-visual biofeedback was devised to improve the reproducibility of respiration
      motion. Recently Neicu et al.13 described results of audio and visual prompting and
      demonstrated improvement in the efficacy of so-called synchronized moving aperture radiation
      therapy, using respiratory traces from single-patient and volunteer sessions.

      George et al.14 concluded based on a 24-patient, multisession study that audio-visual
      biofeedback can significantly reduce residual motion variability for a given duty cycle, thus
      potentially improving the accuracy of respiratory-gating. From the results of this study it
      was seen that audio-visual biofeedback reduced motion by 0.5 cm (0.29 to 0.24 cm) for exhale
      breathing and 1.5 cm (0.46 to 0.36 cm) for inhale breathing.
    

Observational model: Case-Only
Time perspective: Prospective
Sampling method: Probability Sample
Study population: 
        Patients with Abdominal & Thoracic malignancies who consent to recieving Radiation
        treatment at the University of Maryland, Baltimore, will be offered this protocol design.