Predicting the required thickness of custom shielding materials in kilovoltage radiotherapy beams.

The planning and delivery of kilovoltage (kV) radiotherapy treatments involves the use of custom shielding designed and fabricated for each patient. This study investigated methods by which the required thickness of custom shielding could be predicted for non-standard shielding materials fabricated using 3D printing techniques. Seven kV radiation beams from a WOmed T-300 X-ray therapy unit were modelled using SpekPy software, and AAPM TG-61 data were used to account for backscatter and spectral effects, for incrementally increasing thicknesses of Pb, W-PLA composite and Cu-PLA composite materials. The same beams were used to perform physical transmission measurements, and the thickness of each material required to achieve 5% beam transmission was determined. While the measured transmission factors for Pb, W-PLA and Cu-PLA shielding generally exceeded the calculated transmission factors, these differences had minimal effect on the derived thicknesses of shielding required to achieve 5% transmission, where calculations agreed with measurements within 0.5 mm for Pb at all available energies (70-300 kVp), within 1.4 mm for W-PLA at all available energies, and within 2.1 mm for Cu-PLA at superficial treatment energies (70-100 kVp). The incremental transmission factor calculation method described and validated in this study could be used, in combination with the conservative addition of 1-2 mm of additional material, to estimate shielding requirements for novel materials in therapeutic kilovoltage beams. However, if calculated shielding thicknesses equate to 10 mm or more, then additional verification measurements should be performed and the clinical suitability of the novel shielding material should be re-evaluated.

A Tale of 2 Tubes for Emergency Management of Airway Obstruction From an Anterior Mediastinal Mass: A Case Report.

Anterior mediastinal masses are challenging. As induction of general anesthesia may result in complete airway obstruction or hemodynamic collapse, maintaining spontaneous ventilation and advancing the endotracheal tube (ETT) distal to the mass are recommended. We discuss the emergency management of an anterior mediastinal mass-induced near-complete airway obstruction at the carina. Despite maintaining spontaneous ventilation, airway obstruction persisted following placement of the ETT proximal to the obstruction. After advancing the ETT into the right mainstem bronchus distal to the mass, hypoxemia persisted, prompting placement of a second ETT into the left mainstem bronchus to overcome the obstruction and provide adequate oxygenation.

Characteristics of muscle cramps in patients with polyneuropathy.

Muscle cramps are common in the general population and can be disabling for patients, but there is little evidence comprehensively evaluating cramp characteristics in patients with polyneuropathy. This study describes the prevalence and characteristics of muscle cramps in this patient group. Patients over 18 diagnosed with polyneuropathy were invited to join the study. Patients completed nerve conduction studies, the Toronto Clinical Neuropathy score, neuropathy-specific Vickrey's Quality of Life Assessment and a self-administered questionnaire examining demographics, neuropathy symptoms and cramp characteristics. Two hundred and twenty-five participants were enrolled (28.0% female). Sixty-three percent of patients experienced cramps, occurring on average 6 times per week, lasting 10.5 min and scoring 6 out of 10 on a pain scale and described as disabling by 43.6% of patients. No significant difference was found in cramp prevalence according to underlying pathophysiology (p = 0.52) or fiber type (p = 0.41). Patients with disabling cramps rated their physical (p < 0.0001) and mental (p = 0.04) quality of life lower than patients without disabling cramps. This study confirms that muscle cramps are common, disabling and associated with reduced quality of life in patients with polyneuropathy. Similar prevalence of cramps across predominant nerve fiber type suggests a role of sensory afferents in cramp generation, although this needs to be confirmed in larger cohorts.

Association of social support with quality of life in patients with polyneuropathy.

The aim of this study was to examine the impact of social support on quality of life (QoL) in patients with polyneuropathy. One hundred and fifty-four patients with polyneuropathy were enrolled from a neuromuscular clinic. The QoL Instrument and the Medical Outcome Study-Social Support Survey (MOS-SSS) were used to assess QoL and social support, respectively. Disease severity and clinical factors were also assessed. Neuropathy patients had a lower QoL compared to a previously published normative sample (p < 0.0001) and an MOS-SSS comparable to other patients with chronic disease. Social support correlated weakly with the self esteem and emotional well being mental health dimensions (rs :0.20-0.38) but not the physical health QoL (PH-QoL) domains. Physical and mental QoL also correlated significantly with presence of pain (rs : -0.39 and -0.42, respectively) and number of autonomic symptoms (rs : -0.39 and -0.30, respectively). Social support independently predicts MH-QoL when controlling for age, gender, pain, and the Toronto Clinical Neuropathy Score (TCNS; p < 0.0001). TCNS and gender are independently related to PH-QoL (p < 0.05). This study demonstrates that improved social support serves as an independent predictor of MH-QoL when controlling for age, gender, pain, and severity of neuropathy. Future studies examining the effects of improving social support on QoL in patients with polyneuropathy are recommended.