Effects of Respiratory and Cardiac Motion on Dose to the Left Anterior Descending Artery in Patients Undergoing Radiation Therapy for Locally Advanced Lung Cancer

PURPOSE/OBJECTIVE(S)

Radiation dose to the left anterior descending artery (LAD) appears to be an independent predictor of major cardiac events and all-cause mortality following radiation therapy (RT) for lung cancer. In this study, we characterize the dosimetric effects of respiratory (RM) and cardiac (CM) motion on LAD.

MATERIALS/METHODS

Ten patients with stage IIIA-IVA lung cancer received cine MRIs (25 phases) at expiration which were used to evaluate the CM, and 4D CT scans for the evaluation of RM. Following registration of the expiration images of 4D CTs with MRIs, RT dose was transferred from planning CT datasets to all phases of 4D CTs and cine MRIs. LAD was manually contoured on all scans. The contours from each 4D phase represent LADs over multiple cardiac cycles, thus they are referred to as cLAD from here on. Displacements and dose variations of cLAD between exhale/inhale on 4D CTs and of LAD between systolic and diastolic phases on cine MRIs were analyzed, and paired t-tests were performed to assess the significance of the differences observed.

RESULTS

The following metrics are reported averaged over all patients. Clinical treatment planning CT metrics and doses: Mean dose, max dose, V5 Gy and V15 Gy were 15.0 (±11.3) Gy, 31.1 (±22.1) Gy, 53 (±33)%, 35 (±30)%. The cLAD metrics and dose variations due to respiratory motion (between exhale and inhale): RM amplitude was 0.3±0.2cm (RL 0.3 ± 0.1 cm, AP 0.2 ± 0.2 cm, SI 0.3 ± 0.2 cm). The variations in mean dose, max dose, V5 and V15 were 4.0 (±4.0) Gy, 1.6 (±1.5) Gy, 4.4 (±3.4)%, 4.0 (±3.4)%. Mean, max, V5 Gy and V15 Gy increased or remained unchanged with expiration in 8, 9, 5 and 5 patients, respectively. LAD metrics and dose variations due to cardiac motion (between systole and diastole): CM amplitude was 0.2 ± 0.1 cm (RL 0.2 ± 0.1 cm, AP 0.2 ± 0.1 cm, SI 0.3 ± 0.1 cm). The variations in mean dose, max dose, V5 and V15 were 1.7 (±1.4) Gy, 1.2 (±0.9) Gy, 5.2 (± 6.7)%, 4.6 (± 4.0)%. Mean, max, V5 Gy and V15 Gy increased or remained unchanged with diastole in 7, 7, 8 and 8 patients respectively. Statistical significance: The differences in displacement and dose between respiration and cardiac motion were not statistically significant.

CONCLUSION

Respiratory and cardiac-induced physiological variations of the LAD position have dosimetric consequences comparable in magnitude. Expiration and diastole lead to increased LAD doses. This underscores the importance of considering both the respiratory and the cardiac motion when motion management techniques are considered. 4D CTs inherently include the cardiac motion. However, if breath-hold is used for respiratory motion mitigation, CM might not be captured appropriately due to short tube rotation times. In this case, understanding CM characteristics is important for more accurate assessment of LAD dose.

Search for Dark Matter Axions with CAST-CAPP

The CAST-CAPP axion haloscope, operating at CERN inside the CAST dipole magnet, has searched for axions in the 19.74 μeV to 22.47 μeV mass range. The detection concept follows the Sikivie haloscope principle, where Dark Matter axions convert into photons within a resonator immersed in a magnetic field. The CAST-CAPP resonator is an array of four individual rectangular cavities inserted in a strong dipole magnet, phase-matched to maximize the detection sensitivity. Here we report on the data acquired for 4124 h from 2019 to 2021. Each cavity is equipped with a fast frequency tuning mechanism of 10 MHz/ min between 4.774 GHz and 5.434 GHz. In the present work, we exclude axion-photon couplings for virialized galactic axions down to g_aγγ = 8 × 10⁻¹⁴ GeV⁻¹ at the 90% confidence level. The here implemented phase-matching technique also allows for future large-scale upgrades.

Haloscopes aim at detecting axions by converting them into photons using high-quality resonant cavities, where the cavity resonance should be tuned with the unknown axion mass. Here, the authors improve exclusion limits using four phase-matched resonant cavities and a fast frequency scanning technique.

Bioinspired silk fibroin nano-delivery systems protect against 5-FU induced gastrointestinal mucositis in a mouse model and display antitumor effects on HT-29 colorectal cancer cells in vitro

Colorectal cancer (CRC), is the second cause of cancer-related deaths worldwide is one of the most prevalent types of cancers. Conventional treatment continues to rely on surgery, chemotherapy, and radiotherapy, but for advanced cases, adjuvant chemotherapy remains the main approach for improving surgical outcomes and lower the disease recurrence probability. Chemotherapy-induced gastrointestinal (GI) toxicity is the main dose-limiting factor for many chemotherapeutic regimens, including 5-FU, and one of the biggest oncological challenges. Up to 40% of the patients receiving 5-FU get mucositis, 10-15% of which develop severe symptoms. In this context, our study aimed to develop a bioinspired nanosized drug delivery system as a strategy to reduce 5-FU associated side effects, such as GI mucositis. To this end, SF-based nanoparticles were prepared and characterized in terms of size and morphology, as well as in terms of in vitro antitumoral activity on a biomimetic colorectal cancer model by investigation of apoptosis, DNA fragmentation, and release of reactive oxygen species. Additionally, the capacity of the SF-based nanocarriers to offer intestinal protection against 5-FU-induced GI mucositis was evaluated in vivo using a mouse model that mimics the chemotherapy-associated gut mucositis occurring in colorectal cancer. Our studies show that silk fibroin nanoparticles efficiently deliver 5-FU to tumor cells in vitro while protecting against drug-induced GI mucositis in a mouse model.

Acute cardiotoxicity induced by doxorubicin in right ventricle is associated with increase of oxidative stress and apoptosis in rats

Doxorubicin (DOX) is one of the most effective chemotherapeutic agents, but its efficiency is seriously limited by the risk of developing cardiomyopathy. The most recognized cardiotoxic effect is left ventricular (LF) dysfunction, but MRI and echocardiography data demonstrated significant right ventricle (RV) function impairment. In order to clarify this aspect, the present study investigated the potential of DOX to induce acute RV cardiotoxicity at the same time as LV impairment. Rats were intraperitoneally (i.p.) injected with a single dose of 15 mg/kg DOX. DOX-treated rats were characterized by decreased body and heart weights, elevated levels of creatine kinase (CK-MB) and lactate dehydrogenase (LDH) activities compared to controls. Biochemical analyses on RV tissue revealed that the level of malondialdehyde (MDA) was significant increased (p<0.05) and activities of catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPX) antioxidant enzymes were decreased by 13%, 27% and 18%, respectively, compared to control. Histopathogical and electron microscopic studies revealed DOX-induced damage in both ventricles and an increase of interstitial collagen fibers compared to controls (p<0.001), whereas immunohistochemical analysis showed weak and irregular desmin expression. Furthermore, mitochondrion-induced apoptotic pathways were also activated in both ventricles, as reflected by the up-regulation of Bax/Bcl-2 mRNA expression ratio (p<0.001) and increase of Bax and caspase-3 protein expression, as well as by the significant elevation of TUNEL positive nuclei, compared to controls (p<0.001). The results showed that DOX exerted RV toxic effects at the same time as those reported in the LV, which might be mediated through the mitochondrial-dependent apoptosis.

Search for solar axions by the CERN axion solar telescope with 3He buffer gas: closing the hot dark matter gap

The CERN Axion Solar Telescope has finished its search for solar axions with (3)He buffer gas, covering the search range 0.64 eV ≲ ma ≲ 1.17 eV. This closes the gap to the cosmological hot dark matter limit and actually overlaps with it. From the absence of excess x rays when the magnet was pointing to the Sun we set a typical upper limit on the axion-photon coupling of gaγ ≲ 3.3 × 10(-10)  GeV(-1) at 95% C.L., with the exact value depending on the pressure setting. Future direct solar axion searches will focus on increasing the sensitivity to smaller values of gaγ, for example by the currently discussed next generation helioscope International AXion Observatory.

One step forward in health promotion

Thalassemias are inherited blood disorders. In 2011, there was no clear situation regarding the number of thalassemia or other hemoglobinopathy patients in Romania. The luck of information has led to an increased number of patients registered by Fundeni Hospital, Bucharest in the last years. The main goal of this article is to underline the importance of implementing a screening program in Romania for thalassemia and other hemoglobinopathies, parallel with an awareness program. The importance of this objective is strongly supported by the following example: in Sardinia, thalassemia major was present in one out of 250 births, and has declined to one out of 4000 births after they implemented the screening program. The article is written by Monica Rosu, a participant to the World Wide Opportunities for Woman course, held in Canada, in 1999 and states one of the first results of thalassemia awareness in Romania with a positive impact on the patient's life, registering the following results: 2000: A website in Romanian language regarding thalassemias and addressed to patients was created. 2005: The Association of People with thalassemia major was founded and become member of Thalassemia International Federation. 2011: Thalassemia major patients from Romania have access to free treatment and the latest medical oral chelator, Exjade. The association participated in various meetings addressed to patients and doctors as well, created their own website, held workshops, fought together for an improved quality of life for themselves, for healthy people (possible thalassemia carriers) and for all Romanian children.

Search for sub-eV mass solar axions by the CERN Axion Solar Telescope with 3He buffer gas

The CERN Axion Solar Telescope (CAST) has extended its search for solar axions by using (3)He as a buffer gas. At T=1.8 K this allows for larger pressure settings and hence sensitivity to higher axion masses than our previous measurements with (4)He. With about 1 h of data taking at each of 252 different pressure settings we have scanned the axion mass range 0.39 eV≲m(a)≲0.64 eV. From the absence of excess x rays when the magnet was pointing to the Sun we set a typical upper limit on the axion-photon coupling of g(aγ)≲2.3×10(-10) GeV(-1) at 95% C.L., the exact value depending on the pressure setting. Kim-Shifman-Vainshtein-Zakharov axions are excluded at the upper end of our mass range, the first time ever for any solar axion search. In the future we will extend our search to m(a)≲1.15 eV, comfortably overlapping with cosmological hot dark matter bounds.