A Convenient and Effective Preoxygenation Technique for Prolonging Deep Inspiration Breath-Hold Duration With a Venturi Mask With a 50% Oxygen Concentration.

PURPOSE: Voluntary deep inspiration breath-hold (DIBH) is commonly used in radiation therapy (RT), but the short duration of a single breath-hold, estimated to be around 20 to 40 seconds, is a limitation. This prospective study aimed to assess the feasibility and safety of using a simple preoxygenation technique with a Venturi mask to prolong voluntary DIBH. METHODS AND MATERIALS: The study included 33 healthy volunteers and 21 RT patients. Preoxygenation was performed using a Venturi mask with a 50% oxygen concentration. Paired t tests compared the duration of a single DIBH in room air and after 5, 15, and 30 minutes of preoxygenation in healthy volunteers. Sustainability of breath-hold and tolerability of heart rate and blood pressure were assessed for multiple DIBH durations in both volunteers and patients. RESULTS: In healthy volunteers, a 15-minute preoxygenation significantly prolonged the duration of a single DIBH by 24.95 seconds compared with 5-minute preoxygenation (89 ± 27.76 vs 113.95 ± 30.63 seconds; P < .001); although there was a statistically significant increase in DIBH duration after 30-minute preoxygenation, it was only extended by 4.95 seconds compared with 15-minute preoxygenation (113.95 ± 30.63 vs 118.9 ± 29.77 seconds; P < .01). After 15-minute preoxygenation, a single DIBH lasted over 100 seconds in healthy volunteers and over 80 seconds in RT patients, with no significant differences among 6 consecutive cycles of DIBH. Furthermore, there were no significant differences in heart rate or blood pressure after DIBHs, including DIBH in room air and 6 consecutive DIBHs after 15-minute preoxygenation (all P > .05). CONCLUSIONS: Preoxygenation with a 50% oxygen concentration for 15 minutes effectively prolongs the duration of 6 cycles of DIBH both in healthy volunteers and RT patients. The utilization of a Venturi mask to deliver 50% oxygen concentration provides a solution characterized by its convenience, good tolerability, and effectiveness.

Alternating Expiration and Inspiration Breath-Hold Spares the Chest Wall During Stereotactic Body Radiation Therapy for Peripheral Lung Malignancies.

PURPOSE: The proximity of tumors to the chest wall brings additional risks of chest wall pain during stereotactic body radiation therapy. Herein, we dosimetrically compared alternated breath-hold (ABH) plans with single BH plans and determined the common characteristics of eligible patients who may obtain better chest wall sparing using this technique. METHODS AND MATERIALS: Twenty patients with lung lesions adjacent to the chest wall were enrolled and received respiratory training. Their half-fraction end expiration BH and deep inspiration BH plans were summed to generate the ABH plans. Dosimetric parameters of the chest wall were compared between single and alternated BH plans, and the correlation between tumor location and the outcome of chest wall sparing was quantitatively evaluated. Pretreatment cone beam computed tomography variations in eligible patients were recorded as well. RESULTS: Compared with the end expiration BH and deep inspiration BH plans, the ABH plans reduced chest wall dosimetric results with median reductions of 2.0% and 3.9% (Dmax: maximum point dose), 15.4% and 14.8% (D1cc: dose to a volume of 1 cm3), and 48.8% and 63% (V30: volume receiving 30 Gy or more), respectively. Relative tumor displacements (ratio of tumor displacement in the superior-inferior direction to planning target volume diameter) were greater in the lower lobe than in the upper and middle lobes (1.17 vs 0.18). Meanwhile, better median reductions of 44% (Dmax), 46% (D1cc), and 98% (V30) were obtained in the lower lobe cohort using the ABH technique. Pretreatment variations for all BHs met the 5-mm threshold. CONCLUSIONS: The ABH technique can significantly spare the adjacent chest wall without compromising planning target volume coverage in comparison with the single BH, and patients with tumors in the lower lobes can obtain better chest wall sparing than in the upper and middle lobes. Further investigation is warranted to validate these findings.

Protective Role of Shenmai Injection on Radiation-Induced Heart Injury.

Radiation-induced heart injury (RIHI) limits the dose delivery of radiotherapy for thoracic cancer. Shenmai injection (SMI) is reported to have potential cytoprotective properties and is commonly used in cardiovascular diseases. So, we aimed to investigate the potential protective effects of SMI treatment on RIHI. In this study, we established the RIHI model using Sprague-Dawley rats and H9c2 cell line. In vivo, the biochemical assay was used to measure serum cardiac injury-related biomarkers and echocardiography to evaluate heart function. The pathological analysis was also applied to observe the myocardial structural changes. In vitro, we further measured the cell viability and reactive oxygen species (ROS) levels after irradiation with or without SMI treatment. Our data showed the administration of SMI reduced the level of serum cardiac injury biomarkers and ameliorated cardiac dysfunction after irradiation in rats. Pathological analysis revealed that SMI mitigated cardiac structural damage, fibrosis, and macrophage infiltration. Besides, treatment with SMI increased cell viability and decreased excess ROS production after irradiation in vitro. Taken together, our study demonstrated the protective role of SMI treatment on RIHI by inhibiting oxidative stress and decreasing structural remodeling.

Immobilization-assisted abdominal deep inspiration breath-hold in post-mastectomy radiotherapy of left-sided breast cancer with internal mammary chain coverage.

BACKGROUND: Whether to prophylactically irradiate the ipsilateral internal mammary chain (IMC) in post-mastectomy radiotherapy (PMRT) remains controversial because of equivocal clinical benefits against the added toxicities. Our previous study revealed that the cardiac dose was decreased during left-sided breast radiotherapy with abdominal deep inspiration breath-hold (aDIBH) as compared with free-breathing (FB) and thoracic deep inspiration breath-hold (tDIBH). Here we present the dosimetric advantage of aDIBH for patients undergoing PMRT with IMC coverage. METHODS: We prospectively analyzed 19 patients with left-sided breast cancer who underwent PMRT. Patients underwent computed tomography (CT) simulation under both free-breathing (FB) and aDIBH. The heart, left anterior descending coronary artery (LAD), lungs, and the contralateral breast was defined as organs at risk (OARs). Three-dimensional conformal radiation therapy (3D-CRT), inverse planning intensity-modulated radiation therapy (IMRT), and volumetric modulated arc therapy (VMAT) were used to calculate the doses received by both the planning target volume (PTV) and OARs, which were compared using the Wilcoxon signed-rank test. RESULTS: Compared with FB, the Dmean of the heart and LAD were respectively reduced by 3.5 Gy (P<0.003) and 8.9 Gy (P<0.001) in 3D-CRT, 2.6 Gy (P<0.001), and 7.8 Gy (P=0.001) in IMRT, 1.5 Gy (P<0.001) and 4.5 Gy (P=0.001) in VMAT plans under aDIBH. Among all these plans, the Dmean of the heart was lowest in aDIBH IMRT and 1.3 Gy lower than in aDIBH VMAT (P=0.002). aDIBH IMRT also resulted in a significantly reduced dose to the ipsilateral lung than plans under FB (P<0.05). Dmean and V5 to the contralateral lung and breast were higher in VMAT plans (P<0.05). CONCLUSIONS: Using an immobilization-assisted aDIBH technique, radiation doses to the heart can be kept at reasonably low levels even if IMC is included in the clinical target volume (CTV). Among 3D-CRT, IMRT, and VMAT plans, IMRT plus aDIBH results in the best heart-sparing effect. We recommend that the aDIBH technique be routinely applied in suitable patients if the IMC is irradiated.

Comparison of computed tomography- and magnetic resonance imaging-based target delineation for cervical cancer brachytherapy.

PURPOSE: The objective of this study was to compare and assess the accuracy of computed tomography (CT)-based target delineation with that of magnetic resonance imaging (MRI)-based on high-dose-rate brachytherapy (HDR-BT) for patients with cervical cancer. MATERIAL AND METHODS: Data of 20 patients with locally advanced cervical cancer were collected and evaluated. Dimensions, conformity, and dose parameters of high-risk clinical target volume (CTVHR) as well as D0.1cc, D1cc, and D2cc of organs at risk (OARs) based on MRI were compared with those based on CT. RESULTS: Average age of 20 patients included was 57.8 years. Width, thickness, and volumes of CT-based CTVHR (CTVHR-CT) were significantly overestimated compared with those of MRI-based CTVHR (CTVHR-MR). Mean values of dice similarity coefficient (DSC), Hausdorff distance (HD), and centroid distance (ΔV) of CTVHR were 0.82 cm, 0.96 cm, and 0.35 cm, respectively. Dose values of CTVHR-CT were significantly lower compared with those of CTVHR-MR. Concerning OARs, geometrical and dosimetric values on CT were comparable to those on MRI. CONCLUSIONS: The delineated ranges of CTVHR were significantly over-estimated on CT compared with MRI. D98 and D90 of CTVHR-CT were lower than CTVHR-MR. DSC and ΔV of CTVHR and CTVIR were similar to each other; however, there was a difference in terms of HD. CT images regarding pre-BT MR images for delineating were not enough and MRI fusion is still required.

Potential of Gd-EOB-DTPA as an imaging biomarker for liver injury estimation after radiation therapy.

BACKGROUND: Hepatic radiation injury severely restricts irradiation treatment for liver carcinoma. The purpose of this study was to investigate the clinical application of gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced MRI (EOB-MRI) in the assessment of liver function after external radiation therapy and to determine the relationship between focal liver reaction (FLR) and liver function. METHODS: A total of 47 patients with liver malignancies who underwent external beam radiation therapy were enrolled. EOB-MRI was performed on each patient at approximately one month post-radiotherapy. The hepatobiliary (HPB) phase images from EOB-MRI were fused with the planning CT images, and the isodose lines from the patients' treatment plans were overlaid onto the fused images. The correlation of the EOB-MR image intensity distribution with the isodose lines was studied. We also compared liver function in patients between pre-treatment and post-treatment. RESULTS: Decreased uptake of Gd-EOB-DTPA, which was manifested by well-demarcated focal hypointensity of the liver parenchyma or FLR to high-dose radiation, was observed in the irradiated areas of 38 patients. The radiotherapy isodose line of decreased uptake area of Gd-EOB-DTPA was 30-46 Gy. The median corresponding dose curve of FLR was 34.4 Gy. Nine patients showed the absence of decreased uptake area of Gd-EOB-DTPA in the irradiated areas. Compared to the 38 patients with the presence of decreased uptake area of Gd-EOB-DTPA, 9 patients with the absence of decreased uptake area of Gd-EOB-DTPA showed significant higher levels of total bile acid, total bilirubin, direct bilirubin and alpha-fetoprotein (P < 0.05). There were no significant differences in alanine transaminase, aspartate aminotransferase, gamma-glutamyl transpeptidase or albumin levels between the two groups (P > 0.05). CONCLUSIONS: Visible uptake of Gd-EOB-DTPA by the liver parenchyma was significantly associated with liver function parameters. EOB-MRI can be a valuable imaging biomarker for the assessment of liver parenchyma function outside of radiation area.

Abdominal DIBH reduces the cardiac dose even further: a prospective analysis.

BACKGROUND: Deep inspiration breath hold (DIBH) can be performed using different breathing maneuvers, such as DIBH with a thoracic breathing maneuver (T-DIBH) and DIBH with an abdominal breathing maneuver (A-DIBH). Dosimetric benefits of A-DIBH were investigated in the treatment of left-sided breast cancer radiotherapy (RT) with both 3-Dimensional conformal radiation therapy (3D-CRT) and intensity-modulated radiotherapy (IMRT) techniques. METHODS: Twenty-two patients with left-sided breast cancer were enrolled in this study. 3D-CRT and IMRT plans were generated for each patient with three different CT scans of free breathing (FB), T-DIBH and A-DIBH. There were total of six treatment plans generated for each patient: FB_3D-CRT; TDIBH_3D-CRT; ADIBH_3D-CRT; FB-IMRT; TDIBH-IMRT; ADIBH-IMRT. Doses to the heart, left anterior descending coronary artery (LADCA), and ipsilateral lung were evaluated and compared using the Wilcoxon signed-rank test. RESULTS: The mean doses to the heart, LADCA and ipsilateral lung in 3D-CRT plans generated from 3D-CRT with FB, T-DIBH and A-DIBH were (2.89 ± 1.30), (1.67 ± 0.90) and (1.34 ± 0.43) Gy (all P < 0.05), respectively, with FB; (29.08 ± 16.72), (13.94 ± 14.74) and (10.22 ± 10.30) Gy (all P < 0.05), respectively, with T-DIBH; and (7.77 ± 2.71), (7.32 ± 1.42) and (6.90 ± 1.60) Gy (all P < 0.05), respectively, with A-DIBH. The mean doses to the heart, LADCA and ipsilateral lung in IMRT plans were generated from IMRT with FB, T-DIBH and A-DIBH were (1.96 ± 2.25), (1.37 ± 0.44) and (1.18 ± 0.26) Gy (all P < 0.05), respectively, with FB; (16.10 ± 7.45), (8.6 ± 6.60) and (7.35 ± 5.42) Gy (all P < 0.05), respectively, with T-DIBH; and (5.90 ± 2.24), (5.65 ± 1.58) and (5.62 ± 1.05) Gy (all P > 0.05), respectively, with A-DIBH. CONCLUSIONS: This study indicates that both 3D-CRT and IMRT plans with A-DIBH achieved lower cardiac and LADCA doses than plans with FB and T-DIBH; 3D-CRT plans with A-DIBH achieved lower ipsilateral lung doses than plans with FB and T-DIBH; and IMRT plans with A-DIBH had better outcomes than 3D-CRT plans with A-DIBH with respect to the mean dose to the heart, LADCA and ipsilateral lung. IMRT plans with A-DIBH should be incorporated into the daily routine for left-sided breast RT.