Free Breathing Research Articles

Evaluation the effect of wide-body detector CT under free breathing combined with cardiac motion correction technology on CCTA image quality

PurposeTo explore the feasibility of using wide-body detector Computed Tomography (CT) combined with Cardiac Motion Correction (CMC) technology for coronary Computed Tomography angiography (CCTA) in free breathing state and its impact on image quality. Methods120 patients who underwent CCTA scans at our institution from March 2023 to December 2023 were collected in this retrospective study. Recorded the coronary artery images before applying CMC technology as the control group, and the images after applying CMC technology as the experimental group. Patients were divided into two groups by different heart rate (HR), Group A (HR > 70 bpm) and Group B (HR ≤ 70 bpm), with 66 patients in group A and 54 patients in group B. Subjective image quality assessments were performed on the left anterior descending artery (LAD), left circumflex artery (LCX), and right coronary artery (RCA) proximal segments. These assessments were conducted by two senior radiologists using a double-blind approach and a 4-point scale (1 indicating poor image quality and 4 indicating excellent image quality). The subjective scores among the three coronary artery segments were analyzed by chi-square test, using Kappa coefficient to analyze the inter-observer agreement. ResultsThe control group had a subjective score of 3.37 ± 0.81/3.27 ± 0.83 for the LCX, 2.97 ± 0.85/2.93 ± 0.78 for the LAD, and 2.70 ± 0.75/2.80 ± 0.66 for the RCA. The experimental group had a subjective score of 3.90 ± 0.31/3.83 ± 0.38 for the LCX, 3.83 ± 0.38/3.87 ± 0.35 for the LAD, and 3.87 ± 0.35/3.83 ± 0.38 for the RCA. There was a great enhancement in the image quality observed in the experimental group when contrasted with the control group both in group A and group B (all P < 0.05). The inter-observer consistency of LCX, LAD and RCA were 0.726, 0.801 and 0.734 in control group and 0.769, 0.870 and 0.870 in experimental group. ConclusionThe utilization of CMC technology significantly enhances the quality of CCTA images acquired during free breathing.

Evaluation of spine disorders using high contrast imaging of the cartilaginous endplate.

Introduction: Many spine disorders are caused by disc degeneration or endplate defects. Because nutrients entering the avascular disc are channeled through the cartilaginous endplate (CEP), structural and compositional changes in the CEP may block this solute channel, thereby hindering disc cell function. Therefore, imaging the CEP region is important to improve the diagnostic accuracy of spine disorders. Methods: A clinically available T1-weighted and fat-suppressed spoiled gradient recalled-echo (FS-SPGR) sequence was optimized for high-contrast CEP imaging, which utilizes the short T1 property of the CEP. The FS-SPGR scans with and without breath-hold were performed for comparison on healthy subjects. Then, the FS-SPGR sequence which produced optimal image quality was employed for patient scans. In this study, seven asymptomatic volunteers and eight patients with lower back pain were recruited and scanned on a 3T whole-body MRI scanner. Clinical T2-weighted fast spin-echo (T2w-FSE) and T1-weighted FSE (T1w-FSE) sequences were also scanned for comparison. Results: For the asymptomatic volunteers, the FS-SPGR scans under free breathing conditions with NEX = 4 showed much higher contrast-to-noise ratio values between the CEP and bone marrow fat (BMF) (CNRCEP-BMF) (i.e., 7.8 ± 1.6) and between the CEP and nucleus pulposus (NP) (CNRCEP-NP) (i.e., 6.1 ± 1.2) compared to free breathing with NEX = 1 (CNRCEP-BMF: 4.0 ± 1.1 and CNRCEP-NP: 2.5 ± 0.9) and breath-hold condition with NEX = 1 (CNRCEP-BMF: 4.2 ± 1.3 and CNRCEP-NP: 2.8 ± 1.3). The CEP regions showed bright linear signals with high contrast in the T1-weighted FS-SPGR images in the controls, while irregularities of the CEP were found in the patients. Discussion: We have developed a T1-weighted 3D FS-SPGR sequence to image the CEP that is readily translatable to clinical settings. The proposed sequence can be used to highlight the CEP region and shows promise for the detection of intervertebral disc abnormalities.

Accurate quantification of pulmonary perfusion ratio in children with congenital heart disease using partial volume corrected 4D flow cardiac magnetic resonance.

In children with congenital heart disease (CHD), lung scintigraphy is the reference standard for evaluation of pulmonary perfusion. 4D flow CMR offers a non-ionizing alternative. Due to the intrinsic limitation in the spatial resolution, however, 4D flow may display clinically unacceptable differences compared to the reference standard. This case study aims to highlight the importance of correcting for such partial volume errors to accurately evaluate pulmonary perfusion in small pulmonary arteries. Children with CHD, mainly those with transposition of the great arteries or tetralogy-of-Fallot, referred to CMR from 2020 to 2022 at our clinic, were retrospectively reviewed; n = 37. All patients had been examined with a free breathing, motion-corrected 4D flow protocol. Comparison in pulmonary perfusion (PPR: relative flow through right and left pulmonary arteries) with scintigraphy were performed both for 4D flow before and after partial volume correction. Patients with large pulmonary arteries, 76%, displayed small differences in PPR between modalities (<20%), while patients with arteries of only a few pixels, 24%, displayed differences up to 178%, depending on the relative difference in size between the right and left pulmonary artery. Differences were effectively reduced after partial volume correction (<21%). The present report shows that 4D flow is a promising tool to accurately evaluate the pulmonary perfusion in children with CHD, but that partial volume correction is warranted to overcome its limitation in the spatial resolution. Without such correction, lung scintigraphy is still recommended to ensure high diagnostic certainty in children with small pulmonary arteries.

A Prospective Study on the Use of Deep Inspiration Breath-Hold Technique in External Beam Radiotherapy for Breast Cancer

Background Breast cancer is the most common cancer and the leading cause of death in women. The deep inspiration breath-hold (DIBH) technique helps reduce the dose received by the heart and lungs in breast cancers during adjuvant radiotherapy (RT). We present the dosimetry of heart and lungs with DIBH technique, reproducibility, and ease of execution. Materials and Methods This is a prospective study among breast cancer patients planned for adjuvant RT following either breast conservation or mastectomy. Patients received adjuvant RT to a dose of 42.5 Gy/16 Fr to the chest wall/whole breast followed by a boost of 10 Gy/5 Fr for breast conservation surgery patients with either three-dimensional conformal RT or volumetric modulated arc therapy technique. The dosimetric parameters such as lung mean dose, heart mean dose, and V25 Gy were compared between DIBH and free-breathing (FB) scans. Data were analyzed using SPSS software, and p-value &lt;0.05 was considered statistically significant. Results The study was conducted from September 2018 to August 2020, and 32 patients were included. The compliance to the DIBH technique was good. The dose received by ipsilateral lung V20 (17 vs. 25%) and mean dose (9 vs. 12 Gy) were significantly lower in DIBH compared with FB (p &lt; 0.001). The V5 (31 vs. 15%), V25 (9 vs. 2%), and mean dose (7 vs. 3.3 Gy) to the heart were much higher in FB compared with DIBH (p &lt; 0.001). Conclusion DIBH-based RT treatment delivery for breast cancer patients requiring adjuvant RT showed good compliance and offers a significant reduction in radiation dose to the heart and lung.

Study of gas exchange under different modes of ventilation in yoga breathing exercises

Yoga breathing exercises that develop the ability to voluntarily regulate the minute volume of respiration (MV) and maintain the state of hypoventilation, hypoxia and hypercapnia, can be considered as a way of hypoxic-hypercapnic training, potentially capable of influencing cerebral circulation and neuroprotective factors. However, at the moment, individual anthropometric features that affect the ability to develop a hypoventilation mode of breathing have not been studied, and methodological criteria for training have not been developed.Methods: The study involved 44 people (32 men and 12 women) who regularly practice yoga breathing techniques with a voluntary decrease in respiratory rate using maximum tidal volume (TV). Free breathing was recorded for 2 minutes, then each subject performed the respiratory hypoventilation pattern available to him or her (minimum RR values with maximum TV, inhalation and exhalation were of equal duration). The following parameters of external respiration were determined: respiratory rate (RR), minute ventilation (MV), tidal volume (TV), partial pressure of CO2 in the exhaled air at the end of exhalation (PetCO2 ), percentage of O2 in the exhaled air (FeO2) and hemoglobin saturation (SpO2 ).Results: Compared to breathing at rest (MV = M±SD 8.51 ± 2.57 (95% CI 7.72–9.29) l/min; PetCO2 = M±SD 36.98 ± 3.71 (95% CI 35.85–38.11) mm Hg), the mode with RR = 3 times/min (inspiration and expiration for 10 s), n = 44, leads to an increase in MV up to M±SD 12.02 ± 3.42 (95% CI 10.98–13.06) l/min (p &lt; 0.001) and a decrease of CO2 : PetCO2 = M±SD 33.99 ± 3.59 (95% CI 32.90–35.08) mm Hg (p &lt; 0.001) — that is, to development of alveolar hypocapnia. The mode with RR = 1.5 times/min (inhalation and exhalation for 20 s), n = 44, demonstrates a decrease in MV to M±SD 5.95 ± 1.59 (95% CI 5.46–6.43) l/min (p &lt; 0.001) and growth of PetCO2 up to M±SD 41.19 ± 3.71 (95% CI 40.06–42.32) mm Hg (p &lt; 0.001). The mode with RR = 1 time/min (inspiration and exhalation for 30 s), n = 24: with a decrease in RR to 1 time/min, a decrease in MV was observed to M±SD 4.22 ± 0.92 (95% CI 3.83–4.61) l / min (p &lt; 0.001) and an increase in PetCO2 up to M±SD 44.05 ± 3.05 (95% CI 42.76–45.33) mm Hg (p &lt; 0.001). The breathing pattern with RR = 1 r/min is accompanied by a statistically significant decrease in MV compared to rest, as well as an increase in PetCO2 and a decrease in FeO2 , that is, it is hypoventilation. We have proposed a ventilation coefficient (Qvent), which is the ratio MV/VC, which allows us to judge at what values of MV an individual reaches a state of hypoventilation. It was previously shown in this sample that the breathing exercise becomes hypoventilation when Qvent values are equal to or less than 1. With Qvent in the range from 1 to 2, the ventilation mode is within normal values, and when Qvent is more than 2, hyperventilation occurs.Conclusion: when performing yoga breathing exercises, variations in MV are observed both in the direction of hyperventilation and in the direction of hypoventilation with corresponding shifts in gas exchange (hypocapnia with hyperventilation, hypercapnia with hypoventilation). The MV values at which an individual reaches hypoventilation vary from person to person and can be predicted using the ventilation coefficient (Qvent).

Clinical usability of 3D gradient-echo-based ultrashort echo time imaging: Is it enough to facilitate diagnostic decision in real-world practice?

Background With recent advances in magnetic resonance imaging (MRI) technology, the practical role of lung MRI is expanding despite the inherent challenges of the thorax. The purpose of our study was to evaluate the current status of the concurrent dephasing and excitation (CODE) ultrashort echo-time sequence and the T1-weighted volumetric interpolated breath-hold examination (VIBE) sequence in the evaluation of thoracic disease by comparing it with the gold standard computed tomography (CT). Methods Twenty-four patients with lung cancer and mediastinal masses underwent both CT and MRI including T1-weighted VIBE and CODE. For CODE images, data were acquired in free breathing and end-expiratory images were reconstructed using retrospective respiratory gating. All images were evaluated through qualitative and quantitative approaches regarding various anatomical structures and lesions (nodule, mediastinal mass, emphysema, reticulation, honeycombing, bronchiectasis, pleural plaque and lymphadenopathy) inside the thorax in terms of diagnostic performance in making specific decisions. Results Depiction of the lung parenchyma, mediastinal and pleural lesion was not significant different among the three modalities (p &gt; 0.05). Intra-tumoral and peritumoral features of lung nodules were not significant different in the CT, VIBE or CODE images (p &gt; 0.05). However, VIBE and CODE had significantly lower image quality and poorer depiction of airway, great vessels, and emphysema compared to CT (p &lt; 0.05). Image quality of central airways and depiction of bronchi were significantly better in CODE than in VIBE (p &lt; 0.001 and p = 0.005). In contrast, the depiction of the vasculature was better for VIBE than CODE images (p = 0.003). The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were significant greater in VIBE than CODE except for SNRlung and SNRnodule (p &lt; 0.05). Conclusions Our study showed the potential of CODE and VIBE sequences in the evaluation of localized thoracic abnormalities including solid pulmonary nodules.

Dose delivery error from respiratory motion in free breathing left breast irradiation

PurposeMany institutions worldwide currently deliver left breast radiotherapy in free breathing mode, mostly due to the unavailability of a Deep Inspiration Breath Hold technique (DIBH). This study aims at quantifying the error in dose delivery (compared to treatment plan) due to respiratory motion in free breathing irradiation of left breast or chest wall. Since subfields often consist in small, fine-tuned, highly targeted fields, slight intrafractional target motion may compromise their subtle benefit. Thus we analyzed the respiratory motion effect on target dose coverage, dose homogeneity and left lung dose. MethodsTreatment plans for twenty left breast or chest wall cancer patients previously treated at our center were retrieved and retrospectively planned with the introduction of an appropriate shift in isocenter location to simulate free breathing target motion. ResultsNo clinically significant dosimetric changes were found in all twenty cases when breathing motion was accounted for. Changes in target dose coverage (V95%), in target maximum dose (D2%) and in V20Gy lung dose were respectively less than 1.5%, 0.3% and 2.6%. ConclusionThe findings suggest that breast irradiation in free breathing mode does not undermine the dosimetric merits of the field-in-field technique and does not produce clinically significant dosimetric differences in dose delivery for target and lung compared to plan.

Total dose, fraction dose and respiratory motion management impact adrenal SBRT outcome

Purpose/Objective(s)Stereotactic body radiotherapy (SBRT) is an effective treatment for oligometastatic disease in multiple sites. However, the optimal radiation dose for long-term local control of adrenal metastases has yet to be determined. The aim of this study is to evaluate outcomes of adrenal SBRT and to evaluate factors that correlate with local control. Materials/MethodsAfter IRB approval, a retrospective data review of patients treated with SBRT for adrenal metastases at a medical center in Israel between 2015 and 2021 was conducted. A biological effective dose was calculated using an alpha beta ratio of 10. Kaplan Meier and Cox regression were calculated using SPSS software to describe the hazard ratio for local control and survival. Results83 cases of adrenal SBRT were identified. The average age was 67 (range 42–92 years old). Non-small cell lung cancer was the primary site in 44 % of patients. A total of 70 % of the patients had oligometastatic disease (less than five lesions), and the rest were polymetastatic, responding to systemic therapy with oligo progression in the adrenal. The average gross tumor volume (GTV) was 42 ml. Respiratory control was applied in 88 % of cases; 49.3 % used 4-D/ITV, and 38.5 % used breath-hold or continuous positive airway pressure (CPAP) with free breathing. On multivariable analysis, Dose above 75 Gy (biological effective Dose) (HR = 0.41, p = 0.031), Dose above 8 Gy per fraction (HR = 0.53p = 0.038), and breath-holds or CPAP (HR = 0.65, p = 0.047) were significant for local control. From multivariable analysis, we computed a predicted nomogram curve using seven clinical parameters to evaluate local control odds. ConclusionIn this single institution series reported to date, we found unilateral adrenal SBRT safe, yet bilateral treatment harbors a risk of adrenal insufficiency. Biological effective Dose > 75 Gy (BED), motion management with breath-hold or CPAP, and Dose per fraction > 8 Gy were the enhanced local controls. We propose a nomogram to help in decision-making regarding total Dose and Dose per fraction when treating adrenal SBRT.

2422: Comparison of the patient movement in thorax treatments with free breathing and DIBH with SGRT

2422: Comparison of the patient movement in thorax treatments with free breathing and DIBH with SGRT

New full-counts phase-matched data-driven gated (DDG) PET/CT.

Data-driven gated (DDG) PET has gained clinical acceptance and has been shown to match or outperform external-device gated (EDG) PET. However, in most clinical applications, DDG PET is matched with helical CT acquired in free breathing (FB) at a random respiratory phase, leaving registration, and optimal attenuation correction (AC) to chance. Furthermore, DDG PET requires additional scan time to reduce image noise as it only preserves 35%-50% of the PET data at or near the end-expiratory phase of the breathing cycle. A new full-counts, phase-matched (FCPM) DDG PET/CT was developed based on a low-dose cine CT to improve registration between DDG PET and DDG CT, to reduce image noise, and to avoid increasing acquisition times in DDG PET. A new DDG CT was developed for three respiratory phases of CT images from a low dose cine CT acquisition of 1.35mSv for a coverage of about 15.4cm: end-inspiration (EI), average (AVG), and end-expiration (EE) to match with the three corresponding phases of DDG PET data: -10% to 15%; 15% to 30%, and 80% to 90%; and 30% to 80%, respectively. The EI and EE phases of DDG CT were selected based on the physiological changes in lung density and body outlines reflected in the dynamic cine CT images. The AVG phase was derived from averaging of all phases of the cine CT images. The cine CT was acquired over the lower lungs and/or upper abdomen for correction of misregistration between PET and FB CT as well as DDG PET and FB CT. The three phases of DDG CT were used for AC of the corresponding phases of PET. After phase-matched AC of each PET dataset, the EI and AVG PET data were registered to the EE PET data with deformable image registration. The final result was FCPM DDG PET/CT which accounts for all PET data registered at the EE phase. We applied this approach to 14 18F-FDG lung cancer patient studies acquired at 2min/bed position on the GE Discovery MI (25-cm axial FOV) and evaluated its efficacy in improved quantification and noise reduction. Relative to static PET/CT, the SUVmax increases for the EI, AVG, EE, and FCPM DDG PET/CT were 1.67±0.40, 1.50±0.28, 1.64±0.36, and 1.49±0.28, respectively. There were 10.8% and 9.1% average decreases in SUVmax from EI and EE to FCPM DDG PET/CT, respectively. EI, AVG, and EE DDG PET/CT all maintained increased image noise relative to static PET/CT. However, the noise levels of FCPM and static PET were statistically equivalent, suggesting the inclusion of all counts was able to decrease the image noise relative to EI and EE DDG PET/CT. A new FCPM DDG PET/CT has been developed to account for 100% of collected PET data in DDG PET applications. Image noise in FCPM is comparable to static PET, while small decreases in SUVmax were also observed in FCPM when compared to either EI or EE DDG PET/CT.

Feasibility of a portable respiratory training system with a gyroscope sensor.

A portable respiratory training system with a gyroscope sensor (gyroscope respiratory training system [GRTS]) was developed and the feasibility of respiratory training was evaluated. Simulated respiratory waveforms from a respiratory motion phantom and actual respirator waveforms from volunteers were acquired using the GRTS and Respiratory Gating for Scanners system (RGSC). Respiratory training was evaluated by comparing the stability and reproducibility of respiratory waveforms from patients undergoing expiratory breath-hold radiation therapy, with and without the GRTS. The stability and reproducibility of respiratory waveforms were assessed by root mean square error and gold marker placement-based success rate of expiratory breath-hold, respectively. The absolute mean difference for sinusoidal waveforms between the GRTS and RGSC was 2.0%. Among volunteers, the mean percentages of errors within ±15% of the respiratory waveforms acquired by the GRTS and RGSC were 96.1% for free breathing and 88.2% for expiratory breath-hold. The mean root mean square error and success rate of expiratory breath-hold (standard deviation) with and without the GRTS were 0.65 (0.24) and 0.88 (0.89) cm and 91.0% (6.9) and 89.1% (11.6), respectively. Respiratory waveforms acquired by the GRTS exhibit good agreement with waveforms acquired by the RGSC. Respiratory training with the GRTS reduces inter-patient variability in respiratory waveforms, thereby improving the success of expiratory breath-hold radiation therapy. A respiratory training system with a gyroscope sensor is inexpensive and portable, making it ideal for respiratory training. This is the first report concerning clinical implementation of a respiratory training system.

A Prospective Study on Deep Inspiration Breath Hold Thoracic Radiation Therapy Guided by Bronchoscopically Implanted Electromagnetic Transponders.

Electromagnetic transponders bronchoscopically implanted near the tumor can be used to monitor deep inspiration breath hold (DIBH) for thoracic radiation therapy (RT). The feasibility and safety of this approach require further study. We enrolled patients with primary lung cancer or lung metastases. Three transponders were implanted near the tumor, followed by simulation with DIBH, free breathing, and 4D-CT as backup. The initial gating window for treatment was ±5 mm; in a second cohort, the window was incrementally reduced to determine the smallest feasible gating window. The primary endpoint was feasibility, defined as completion of RT using transponder-guided DIBH. Patients were followed for assessment of transponder- and RT-related toxicity. We enrolled 48 patients (35 with primary lung cancer and 13 with lung metastases). The median distance of transponders to tumor was 1.6 cm (IQR 0.6-2.8 cm). RT delivery ranged from 3 to 35 fractions. Transponder-guided DIBH was feasible in all but two patients (96% feasible), where it failed because the distance between the transponders and the antenna was >19 cm. Among the remaining 46 patients, 6 were treated prone to keep the transponders within 19 cm of the antenna, and 40 were treated supine. The smallest feasible gating window was identified as ±3 mm. Thirty-nine (85%) patients completed one year of follow-up. Toxicities at least possibly related to transponders or the implantation procedure were grade 2 in six patients (six incidences, cough and hemoptysis), grade 3 in three patients (five incidences, cough, dyspnea, pneumonia, and supraventricular tachycardia), and grade 4 pneumonia in one patient (occurring a few days after implantation but recovered fully and completed RT). Toxicities at least possibly related to RT were grade 2 in 18 patients (41 incidences, most commonly cough, fatigue, and pneumonitis) and grade 3 in four patients (seven incidences, most commonly pneumonia), and no patients had grade 4 or higher toxicity. Bronchoscopically implanted electromagnetic transponder-guided DIBH lung RT is feasible and safe, allowing for precise tumor targeting and reduced normal tissue exposure. Transponder-antenna distance was the most common challenge due to a limited antenna range, which could sometimes be circumvented by prone positioning.

A comparative study in left-sided breast cancer treated with moderate deep inspiratory breath hold versus free breathing

BackgroundThe moderate deep inspiratory breath hold (mDIBH) is a modality famed for cardiac sparing. Prospective studies based on this are few from the eastern part of the world and India. We intend to compare the dosimetry between mDIBH and free-breathing (FB) plans.MethodsThirty-two locally advanced left breast cancer patients were taken up for the study. All patients received a dose of 50 Gy in 25 fractions to the chest wall/intact breast, followed by a 10-Gy boost to the lumpectomy cavity in the case of breast conservation surgery. All the patients were treated in mDIBH using active breath coordinator (ABC). The data from the two dose volume histograms were compared regarding plan quality and the doses received by the organs at risk. Paired t-test was used for data analysis.ResultsThe dose received by the heart in terms of V5, V10, and V30 (4.55% vs 8.39%) and mean dose (4.73 Gy vs 6.74 Gy) were statistically significant in the ABC group than that in the FB group (all p-values < 0.001). Also, the dose received by the LADA in terms of V30 (19.32% vs 24.87%) and mean dose (32.99 Gy vs 46.65 Gy) were significantly less in the ABC group. The mean treatment time for the ABC group was 20 min, while that for the free-breathing group was 10 min.ConclusionsIncorporating ABC-mDIBH for left-sided breast cancer radiotherapy significantly reduces the doses received by the heart, LADA, and left and right lung, with no compromise in plan quality but with an increase in treatment time.

Comparison of deep inspiration breath hold and free breathing intensity modulated proton therapy of locally advanced lung cancer

Background and purposeFor locally advanced non-small cell lung cancer (LA-NSCLC), intensity-modulated proton therapy (IMPT) can reduce organ at risk (OAR) doses compared to intensity-modulated radiotherapy (IMRT). Deep inspiration breath hold (DIBH) reduces OAR doses compared to free breathing (FB) in IMRT. In IMPT, differences in dose distributions and robustness between DIBH and FB are unclear. In this study, we compare DIBH to FB in IMPT, and IMPT to IMRT. Materials and methodsFortyone LA-NSCLC patients were prospectively included. 4D computed tomography images (4DCTs) and DIBH CTs were acquired for treatment planning and during weeks 1 and 3 of treatment. A new system for automated robust planning was developed and used to generate a FB and a DIBH IMPT plan for each patient. Plans were compared in terms of dose-volume parameters and normal tissue complication probabilities (NTCPs). Dose recalculations on repeat CTs were used to compare inter-fraction plan robustness. ResultsIn IMPT, DIBH reduced median lungs Dmean from 9.3 Gy(RBE) to 8.0 Gy(RBE) compared to FB, and radiation pneumonitis NTCP from 10.9 % to 9.4 % (p < 0.001). Inter-fraction plan robustness for DIBH and FB was similar. Median NTCPs for radiation pneumonitis and mortality were around 9 percentage points lower with IMPT than IMRT (p < 0.001). These differences were much larger than between FB and DIBH within each modality. ConclusionDIBH IMPT resulted in reduced lung dose and radiation pneumonitis NTCP compared to FB IMPT. Inter-fraction robustness was comparable. OAR doses were far lower in IMPT than IMRT.

DIBH reduces right coronary artery and lung radiation dose in right breast cancer loco-regional radiotherapy

To determine whether deep inspiratory breath-hold (DIBH) reduces dose to organs-at-risk (OAR), in particular the right coronary artery (RCA), in women with breast cancer requiring right-sided post-mastectomy radiotherapy (PMRT) including internal mammary chain (+IMC) radiotherapy (RT). Fourteen consecutive women requiring right-sided PMRT + IMC were retrospectively identified. Nodal delineation was in accordance with European Society for Radiology and Oncology (ESTRO) guidelines and tangential chest wall fields marked. Patients were planned with Anisotropic Analytical Algorithm using free-breathing (FB) and DIBH datasets. Dose was calculated using Acuros External Beam algorithm. FB and DIBH dose comparisons were analyzed for heart, RCA and right lung, as were chest wall and IMC planning target volumes (PTVs). DIBH vs FB resulted in median decreases of: the RCA mean dose by 0.6Gray (Gy) (interquartile range (IQR) 0.1, 1.9) (p = 0.002), RCA max dose by 1.8Gy (IQR 0.8, 6.1) (p = 0.002), and V5Gy by 2.9% (IQR 0.0, 37.2) (p = 0.016). RCA data indicated no statistically significant dosimetric reduction ≥10Gy. A median reduction of 1.7Gy (c -0.0, 7.1) (p = 0.019) in maximum heart dose was recorded with DIBH vs FB; no significant difference was observed in other heart and left anterior descending coronary artery parameters. The median reduction in right lung mean dose was 2.8Gy for DIBH vs FB plans (IQR 1.6, 3.6) (p = 0.001); significant median reductions of V5Gy, V20Gy, and V30Gy were all achieved with DIBH. Chest wall PTV coverage did not significantly differ between DIBH and FB plans; IMC dosimetric coverage improved with use of DIBH (V47.5Gy, V45Gy, V42Gy). DIBH reduced OAR dose in right-sided PMRT + IMC patients. A novel finding was that DIBH decreased RCA dose. Heart and right lung dose were also decreased with DIBH, whilst optimally dosed PTVs were maintained.

Hybrid method for noise rejection from breath sound using transient artifact reduction algorithm and spectral subtraction.

Computerized breath sound based diagnostic methods are one of the emerging technologies gaining popularity in terms of detecting respiratory disorders. However, the breath sound signal used in such automated systems used to be too noisy, which affects the quality of the diagnostic interpretations. To address this problem, the proposed work presents the new hybrid approach to reject the noises from breath sound. In this method, 80 chronic obstructive pulmonary disease (COPD), 75 asthmatics and 80 normal breath sounds were recorded from the participants of a hospital. Each of these breath sound data were decontaminated using hybrid method of Butterworth band-pass filter, transient artifact reduction algorithm and spectral subtraction algorithm. The study examined the algorithms noise rejection potential over each category of breath sound by estimating the noise rejection performance metrics, i.e.,mean absolute error (MAE), mean square error (MSE), peak signal to noise ratio (PSNR), and signal to noise ratio (SNR). Using this algorithm, the study obtained a high value of SNR of 70 dB and that of PSNR of 72 dB. The study could definitely a suitable one to suppress noises and to produce noise free breath sound signal.

A Wearable Open-Source electrical impedance tomography device

Electrical impedance tomography (EIT) is medical imaging technique in which small electrical signals are used to map the electrical impedance distribution within the body. It is safe and non-invasive, which make it attractive for use in continuous monitoring or outpatient applications, but the high cost of commercial devices is an impediment to its adoption. Over the last 10 years, many research groups have developed their own EIT devices, but few designs for open-source EIT hardware are available. In this work, we present a complete open-source EIT system that is designed to be suitable for monitoring the lungs of free breathing subjects. The device is low-cost, wearable, and is designed to comply with the industry accepted safety standard for EIT. The device has been tested in two regimes: Firstly in terms of measurement uncertainty as a voltage measurement system, and secondly against a set of measures that have been proposed specifically for EIT hardware. The voltage measurement uncertainty of the device was measured to be − 0.7 % ± 0.36 mV. The EIT specific performance was measured in a phantom test designed to be as physiologically representative as practicable, and the device performed similarly to other published devices. This work will contribute to increased accessibility of EIT for study and will contribute to consensus on testing methodology for EIT devices.

Deep inspiratory breath-hold radiotherapy on a Helical Tomotherapy unit: Workflow and early outcomes in patients with left-sided breast cancer

IntroductionThe clinical implementation of deep inspiratory breath-hold (DIBH) radiotherapy to reduce cardiac exposure in patients with left-sided breast cancer is challenging with helical tomotherapy(HT) and has received little attention. We describe our novel approach to DIBH irradiation in HT using a specially designed frame and manual gating, and compare cardiac substructure doses with the free-breathing (FB) technique. Material and methodsThe workflow incorporates staggered junctions and a frame that provides tactile feedback to the patient and monitoring for manual cut-off. The treatment parameters and clinical outcome of 20 patients with left-sided breast cancer who have undergone DIBH radiotherapy as a part of an ongoing prospective registry are reported. All patients underwent CT scans in Free Breathing (FB) and DIBH using the in-house Respiframe, which incorporates a tactile feedback-based system with an indicator pencil. Plans compared target coverage, cardiac doses, synchronizing treatment with breath-hold and avoiding junction repetition. MVCT scans are used for patient alignment. ResultsThe mean dose (Dmean) to the heart was reduced by an average of 34 % in DIBH-HT compared to FB-HT plans (3.8 Gy vs 5.7 Gy). Similarly, 32 % and 67.8 % dose reduction were noted in the maximum dose (D0.02 cc) of the left anterior descending artery, mean 12.3 Gy vs 18.1 Gy, and mean left ventricle V5Gy 13.2 % vs 41.1 %, respectively. The mean treatment duration was 451.5 sec with a median 8 breath-holds; 3 % junction locations between successive breath-holds were replicated. No locoregional or distant recurrences were observed in the 9-month median follow-up. ConclusionOur workflow for DIBH with Helical-Tomotherapy addresses patient safety, treatment precision and challenges specific to this treatment unit. The workflow prevents junction issues by varying daily breath-hold durations and avoiding junction locations, providing a practical solution for left-sided breast cancer treatment with HT.

Comparing interplay effects in scanned proton therapy of lung cancer: Free breathing with various layer and volume rescanning versus respiratory gating with different gate widths

PurposeWe investigated interplay effects and treatment time (TT) in scanned proton therapy for lung cancer patients. We compared free-breathing (FB) approaches with multiple rescanning strategies and respiratory-gating (RG) methods with various gating widths to identify the superior irradiation technique. MethodsPlans were created with 4/1, 2/2, and 1/4 layered/volume rescans of FB (L4V1, L2V2, and L1V4), and 50%, 30%, and 10% gating widths of the total respiratory curves (G50, G30, and G10) of the RG plans with L4V1. We calculated 4-dimensional dynamic doses assuming a constant sinusoidal curve for six irradiation methods. The reconstructed doses per fraction were compared with planned doses in terms of dose differences in 99% clinical-target-volume (CTV) (ΔD99%), near-maximum dose differences (ΔD2%) at organs-at-risk (OARs), and TT. ResultsThe mean/minimum CTV ΔD99% values for FB were −1.0%/−4.9%, −0.8%/−4.3%, and −0.1%/−1.0% for L4V1, L2V2, and L1V4, respectively. Those for RG were −0.3%/−1.7%, −0.1%/−1.0%, and 0.0%/−0.5% for G50, G30, and G10, respectively. The CTV ΔD99% of the RGs with less than 50% gate width and the FBs of L1V4 were within the desired tolerance (±3.0%), and the OARs ΔD2% for RG were lower than those for FB. The mean TTs were 90, 326, 824, 158, 203, and 422 s for L4V1, L2V2, L1V4, G50, G30, and G10, respectively. ConclusionsFB (L4V1) is the most efficient treatment, but not necessarily the optimal choice due to interplay effects. To satisfy both TT extensions and interplay, RG with a gate width as large as possible within safety limits is desirable.

Validating the accuracy of real-time phase-contrast MRI and quantifying the effects of free breathing on cerebrospinal fluid dynamics

BackgroundUnderstanding of the cerebrospinal fluid (CSF) circulation is essential for physiological studies and clinical diagnosis. Real-time phase contrast sequences (RT-PC) can quantify beat-to-beat CSF flow signals. However, the detailed effects of free-breathing on CSF parameters are not fully understood. This study aims to validate RT-PC’s accuracy by comparing it with the conventional phase-contrast sequence (CINE-PC) and quantify the effect of free-breathing on CSF parameters at the intracranial and extracranial levels using a time-domain multiparametric analysis method.MethodsThirty-six healthy participants underwent MRI in a 3T scanner for CSF oscillations quantification at the cervical spine (C2-C3) and Sylvian aqueduct, using CINE-PC and RT-PC. CINE-PC uses 32 velocity maps to represent dynamic CSF flow over an average cardiac cycle, while RT-PC continuously quantifies CSF flow over 45-seconds. Free-breathing signals were recorded from 25 participants. RT-PC signal was segmented into independent cardiac cycle flow curves (Qt) and reconstructed into an averaged Qt. To assess RT-PC’s accuracy, parameters such as segmented area, flow amplitude, and stroke volume (SV) of the reconstructed Qt from RT-PC were compared with those derived from the averaged Qt generated by CINE-PC. The breathing signal was used to categorize the Qt into expiratory or inspiratory phases, enabling the reconstruction of two Qt for inspiration and expiration. The breathing effects on various CSF parameters can be quantified by comparing these two reconstructed Qt.ResultsRT-PC overestimated CSF area (82.7% at aqueduct, 11.5% at C2-C3) compared to CINE-PC. Stroke volumes for CINE-PC were 615 mm³ (aqueduct) and 43 mm³ (spinal), and 581 mm³ (aqueduct) and 46 mm³ (spinal) for RT-PC. During thoracic pressure increase, spinal CSF net flow, flow amplitude, SV, and cardiac period increased by 6.3%, 6.8%, 14%, and 6%, respectively. Breathing effects on net flow showed a significant phase difference compared to the other parameters. Aqueduct-CSF flows were more affected by breathing than spinal-CSF.ConclusionsRT-PC accurately quantifies CSF oscillations in real-time and eliminates the need for cardiac synchronization, enabling the quantification of the cardiac and breathing components of CSF flow. This study quantifies the impact of free-breathing on CSF parameters, offering valuable physiological references for understanding the effects of breathing on CSF dynamics.