Thermoplastic polymers as water substitutes

Background. New applications of 3D printing have recently appeared in the fields of radiotherapy and radiology, but the knowledge of many radiological characteristics of the compounds involved is still limited. Therefore, studies are needed to improve our understanding about the transport and interaction of ionizing radiation in these materials.Purpose. The purpose of this study is to perform an analysis of the most important radiation interaction parameters in thermoplastic materials used in Fused Deposition Modeling 3D printing. Additionally, we propose improvements to bring their characteristics closer to those of water and use them as water substitutes in applications such as radiodiagnosis, external radiotherapy, and brachytherapy.Methods. We have calculated different magnitudes as mass linear attenuation, mass energy absorption coefficients, as well as stopping power and electronic density of several thermoplastic materials along with various compounds that have been used as water substitutes and in a new proposed blend. To perform these computations, we have used the XCOM and ESTAR databases from NIST and the EGSnrc code for Montecarlo simulations.Results. From the representation of the calculated interaction parameters, we have been able to establish relationships between their properties and the proportion of certain chemical elements. In addition, studying these same characteristics in different commercial solutions used as substitutes for water phantoms allows us to extrapolate improvements for these polymers.Conclusion. The radiological characteristics of the analyzed thermoplastic materials can be improved by adding some chemical elements with atomic numbers higher than oxygen and by using polyethylene in new blends.

Open-window thoracostomy and thoracomyoplasty to manage chronic pleural empyema

BACKGROUND

The purpose of this study is to report our 15-year experience treating chronic empyemas after pulmonary resection and tuberculosis.

METHODS

Open-window thoracostomy and thoracomyoplasty were used to treat 40 patients with chronic pleural empyema characterized by residual empyematic cavity, bronchopleural fistula, and persistent pleural infections that were secondary to tuberculosis (n = 22) or pulmonary resection (n = 18). Between 2 and 7 months after thoracostomy, thoracomyoplasty was performed to eliminate a persistent pleural cavity. In 2 patients with postpulmonary resection empyema and a large bronchopleural fistula, intrathoracic transposition of the latissimus dorsi flap and open-window thoracostomy were performed simultaneously to close the fistula.

RESULTS

The pleural space was eliminated per primam intentionem in 21 of 22 patients with tuberculosis and in 14 of 18 with a postpulmonary resection empyema. Another myoplasty was performed in an additional 3 patients to eliminate the pleural space. During open-window thoracostomy, the latissimus dorsi muscle was preserved with minimal injury to the anterior serratus muscle. One patient died postoperatively.

CONCLUSIONS

Successful treatment of chronic pleural empyema requires adequate timing of surgical procedures. Our two-procedure technique is relatively simple and safe.

[Schwannoma of the intrathoracic vagus nerve]

Schwannomas, or neurilemomas, are tumors that originate in the sheaths covering peripheral nerve fibers. They are usually encapsulated, slow growing, and asymptomatic. Such tumors may appear in any nerve, although most are found in the extremities. Intrathoracic vagus schwannomas are very rare and only 72 cases have been reported. We present a new case in a 39-year-old man in whom chest film showed a well-defined, homogeneous mass measuring 3 cm in diameter located in the left para-aortic region. The presence of a smooth tumor on the vagus nerve and recurrent loop was confirmed by left lateral thoracotomy. After removal, the tumor was shown to be a vagal nerve schwannoma.

Early complications in surgical treatment of lung cancer: a prospective, multicenter study. Grupo Cooperativo de Carcinoma Broncogénico de la Sociedad Española de Neumología y Cirugía Torácica

BACKGROUND

We prospectively analyzed the postoperative morbidity, mortality rate, and risk factors in 605 patients who underwent thoracotomy for bronchogenic carcinoma.

METHODS

Patients were categorized by postsurgical tumor stage: I, 287 patients (47.4%); II, 49 patients (8.1%); IIIA, 154 patients (25.5%); IIIB, 80 patients (13.2%); IV, 16 patients (2.7%); unavailable, 19 patients (3.1%). Two hundred ninety-four patients (48.6%) underwent lobectomy, 172 (28.4%) pneumonectomy, 20 (3.3%) bilobectomy, 29 (4.8%) segmentectomy, 27 (4.5%) wedge resection, and 63 (10.4%) exploratory thoracotomy. The importance of the factors that influence the morbidity and mortality rates was calculated from their relative risks. Univariate and multivariate methods for a logistic regression model were used for this analysis.

RESULTS

Postoperative complications developed in 196 patients (32.4%); there were 165 (27.3%) cases of operation-related complications and 152 (25.1%) cases of respiratory and cardiovascular complications. The morbidity rate was highest in patients with preexisting vascular disease (50.9%; odds ratio [OR], 2.20) or insulin-dependent diabetes mellitus (52.4%; OR, 2.77) and in patients who underwent pneumonectomy (40.1%; OR, 1.82). Forty patients (6.6%) died postoperatively, most commonly of respiratory failure (67.5%). The mortality rate was highest in patients with postoperative morbidity (OR, 31.9) or vascular disease (15.8%; OR, 2.83) and in patients who underwent pneumonectomy (13.4%; OR, 4.9).

CONCLUSIONS

Postoperative complications are more likely to develop in patients with peripheral vascular disease or insulin-dependent diabetes mellitus, or both. Postoperative mortality was found to be significantly higher in patients with vascular disease and those who underwent pneumonectomy.