Mitigating Respiratory Motion in Radiation Therapy: Rapid, Shallow, Non-invasive Mechanical Ventilation for Internal Thoracic Targets

West, Nick; Parkes, M. J.; Snowden, Christopher; Prentis, James; McKenna, Jill; Iqbal, Muhammad Shahid; Cashmore, J.; Walker, Christopher

doi:10.1016/j.ijrobp.2018.11.040

Cited by 10 publications

(11 citation statements)

References 22 publications

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“…In intensive care, non-invasive mechanical ventilation of unsedated patients has been developed over the last decades [ 18 ]. More recently, non-invasive mechanical ventilation has been explored in radiotherapy [ 19 – 24 ]. Another strategy under investigation is the use of continuous positive airway pressure which is originally meant to treat patients with sleep apnea and patients with chronic obstructive pulmonary disease [ 25 – 28 ].…”

Section: Introductionmentioning

confidence: 99%

“…We aimed to investigate the advantages of rhythmic mechanical ventilation with positive pressure in reducing diaphragm motion. Mechanical ventilation offers radiotherapy two means of reducing organ motion, first by regularized breathing [ 23 , 24 ] (RB), and second by PBH achieved by combining ventilation with preoxygenation and induced hypocapnia [ 20 , 21 , 34 ]. We are the first to compare diaphragm motion during free breathing (FB), multiple DIBHs, RB at 22 breaths per minute (brpm), and single PBH, all repeatedly performed by each of the healthy volunteers and measured with MRI.…”

Section: Introductionmentioning

confidence: 99%

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Quantifying the reduction of respiratory motion by mechanical ventilation with MRI for radiotherapy

et al. 2022

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Background Due to respiratory motion, accurate radiotherapy delivery to thoracic and abdominal tumors is challenging. We aimed to quantify the ability of mechanical ventilation to reduce respiratory motion, by measuring diaphragm motion magnitudes in the same volunteers during free breathing (FB), mechanically regularized breathing (RB) at 22 breaths per minute (brpm), variation in mean diaphragm position across multiple deep inspiration breath-holds (DIBH) and diaphragm drift during single prolonged breath-holds (PBH) in two MRI sessions. Methods In two sessions, MRIs were acquired from fifteen healthy volunteers who were trained to be mechanically ventilated non-invasively We measured diaphragm motion amplitudes during FB and RB, the inter-quartile range (IQR) of the variation in average diaphragm position from one measurement over five consecutive DIBHs, and diaphragm cranial drift velocities during single PBHs from inhalation (PIBH) and exhalation (PEBH) breath-holds. Results RB significantly reduced the respiratory motion amplitude by 39%, from median (range) 20.9 (10.6–41.9) mm during FB to 12.8 (6.2–23.8) mm. The median IQR for variation in average diaphragm position over multiple DIBHs was 4.2 (1.0–23.6) mm. During single PIBHs with a median duration of 7.1 (2.0–11.1) minutes, the median diaphragm cranial drift velocity was 3.0 (0.4–6.5) mm/minute. For PEBH, the median duration was 5.8 (1.8–10.2) minutes with 4.4 (1.8–15.1) mm/minute diaphragm drift velocity. Conclusions Regularized breathing at a frequency of 22 brpm resulted in significantly smaller diaphragm motion amplitudes compared to free breathing. This would enable smaller treatment volumes in radiotherapy. Furthermore, prolonged breath-holding from inhalation and exhalation with median durations of six to seven minutes are feasible. Trial registration Medical Ethics Committee protocol NL.64693.018.18.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Quantifying the reduction of respiratory motion by mechanical ventilation with MRI for radiotherapy

et al. 2022

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“…This is easily tolerated in conscious and unmedicated subjects and provides an entirely uniform pattern of lung inflation and more severe, prolonged and stable hypocapnia at 20 mmHg without any consistent pressor or electrolyte changes. Indeed such non-invasive mechanical hyperventilation has widespread clinical application e.g., for radiotherapy to assist cardiac ablation and to reduce movement during all radiotherapy in the thorax and abdomen (Parkes et al, 2016a,b;West et al, 2018;Van Ooteghem et al, 2019). But there is still little clinical awareness of the simplicity, availability, and safety of this technique.…”

Section: Discussionmentioning

confidence: 99%

“…Since mechanically induced hypocapnia is so simple, cheap and comfortable (for patients) to perform, it is potentially viable as a diagnostic modality for identifying patients with fixed coronary stenoses. Furthermore, non-invasive mechanical ventilation is now being considered to assist radiotherapy, both for cardiac ablation and for radiotherapy delivery to reduce respiratory motion of thoracic and abdominal cancers (Parkes et al, 2016b;West et al, 2018;Van Ooteghem et al, 2019). There is therefore a need to demonstrate whether it would be well tolerated in patients with co-morbid coronary artery disease.…”

Section: Introductionmentioning

confidence: 99%

Hypocapnia Alone Fails to Provoke Important Electrocardiogram Changes in Coronary Artery Diseased Patients

et al. 2020

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Background: There is still an urgent clinical need to develop non-invasive diagnostic tests for early ischemic heart disease because, once angina occurs, it is too late. Hypocapnia has long been known to cause coronary artery vasoconstriction. Some new cardiology tests are accompanied by the claim that they must have potential diagnostic value if hypocapnia enhances their cardiac effects in healthy subjects. But no previous study has tested whether hypocapnia produces bigger cardiac effects in patients with angina than in healthy subjects. Methods: Severe hypocapnia (a PetCO 2 level of 20 mmHg) lasting >15 min was mechanically induced by facemask, while conscious and unmedicated, in 18 healthy subjects and in 10 patients with angina and angiographically confirmed coronary artery disease, awaiting bypass surgery. Each participant was their own control in normocapnia (where CO 2 was added to the inspirate) and the order of normocapnia and hypocapnia was randomized. Twelve lead electrocardiograms (ECG) were recorded and automated measurements were made on all ECG waveforms averaged over >120 beats. 2D echocardiography was also performed on healthy subjects. Results: In the 18 healthy subjects, we confirm that severe hypocapnia (a mean PetCO 2 of 20 ± 0 mmHg, P < 0.0001) consistently increased the mean T wave amplitude in leads V1-V3, but by only 31% (P < 0.01), 15% (P < 0.001) and 11% (P < 0.05), respectively. Hypocapnia produced no other significant effects (p > 0.05) on their electro-or echocardiogram. All 10 angina patients tolerated the mechanical hyperventilation well, with minimal discomfort. Hypocpania caused a similar increase in V1 (by 39%, P < 0.05 vs. baseline, but P > 0.05 vs. healthy controls) and did not induce angina. Its effects were no greater in patients who did not take β-blockers, or did not take organic nitrates, or had the worst Canadian Cardiovascular Society scores.

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“…West et al used rapid, shallow, noninvasive ventilation to induce the frequencies of healthy volunteers with 20 and 25 breaths/min . In Shen’s experiment, the anesthetized adult rabbit’s respiratory rate remained at 70 breaths/min .…”

Section: Discussionmentioning

confidence: 99%

Respiratory motion correction for liver contrast‐enhanced ultrasound by automatic selection of a reference image

Zhang

Chen

et al. 2019

Medical Physics

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Purpose: Respiratory motion correction is necessary for the quantitative analysis of liver contrastenhanced ultrasound (CEUS) image sequences. Most respiratory motion correction methods are based on the dual mode of CEUS image sequences, including contrast and grayscale image sequences. Due to free-breathing motion, the acquired two-dimensional (2D) ultrasound cine might show the in-plane and out-of-plane motion of tumors. The registration of an entire 2D ultrasound contrast image sequence based on out-of-plane images is ineffective. For the respiratory motion correction of CEUS sequences, the reference image is usually considered the standard for the deletion of any out-of-plane images. Most methods used for the selection of the reference image are subjective in nature. Here, a quantitative selection method for an optimal reference image from CEUS image sequences in the B mode and contrast mode was explored. Methods: The original high-dimensional ultrasound grayscale image data were mapped into a twodimensional space using Laplacian Eigenmaps (LE), and K-means clustering was adopted. The center image of the larger cluster with a near-peak contrast intensity was considered the optimal ultrasound reference image. In the ultrasound grayscale image sequence, the images with the maximum correlations to the reference image in the same time interval were selected as the corrected image sequence. The effectiveness of this proposed method was then validated on 18 CEUS cases of VX2 tumors in rabbit livers. Results: Correction smoothed the time-intensity curves (TICs) extracted from the region of interest of the CEUS image sequences. Before correction, the average of the total mean structural similarity (TMSSIM) and the average of the mean correlation coefficient (MCC) from the image sequences were 0.45 AE 0.11 and 0.67 AE 0.16, respectively, and after correction, the average TMSSIM and MCC increased (P < 0.001) by 31% to 0.59 AE 0.11 and by 21% to 0.81 AE 0.11, respectively. The average deviation value (DV) index of the TICs from the image sequences prior to correction was 92.16 AE 18.12, and correction reduced the average to 31.71 AE 7.31. The average TMSSIM and MCC values after correction using the mean frame of the reference image (MBMFRI) were clearly lower than those after correction using the proposed method (P < 0.001). Moreover, the average DV after correction using the MBMFRI was obviously higher than that after correction using the proposed method (P < 0.001). Conclusions: The breathing frequency of rabbits is notably faster than that of human beings, but the proposed correction method could reduce the effect of the respiratory motion in the CEUS image sequences. The reference image was selected quantitatively, which could improve the accuracy of the quantitative analysis of rabbit liver CEUS sequences using the reference image method based on the current standard of manual selection and the MBMFRI. This easy-to-operate method can potentially be used in both animal studies and clinical applications.

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Mitigating Respiratory Motion in Radiation Therapy: Rapid, Shallow, Non-invasive Mechanical Ventilation for Internal Thoracic Targets

Cited by 10 publications

References 22 publications

Quantifying the reduction of respiratory motion by mechanical ventilation with MRI for radiotherapy

Quantifying the reduction of respiratory motion by mechanical ventilation with MRI for radiotherapy

Hypocapnia Alone Fails to Provoke Important Electrocardiogram Changes in Coronary Artery Diseased Patients

Respiratory motion correction for liver contrast‐enhanced ultrasound by automatic selection of a reference image

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