Reliability, clinical performance and trending ability of a pulse oximeter and pulse co-oximeter, in monitoring blood oxygenation, at two measurement sites, in immobilised white rhinoceros (Ceratotherium simum).

BACKGROUND: Monitoring blood oxygenation is essential in immobilised rhinoceros, which are susceptible to opioid-induced hypoxaemia. This study assessed the reliability, clinical performance and trending ability of the Nonin PalmSAT 2500 A pulse oximeter's and the Masimo Radical-7 pulse co-oximeter's dual-wavelength technology, with their probes placed at two measurement sites, the inner surface of the third-eyelid and the scarified ear pinna of immobilised white rhinoceroses. Eight white rhinoceros were immobilised with etorphine-based drug combinations and given butorphanol after 12 min, and oxygen after 40 min, of recumbency. The Nonin and Masimo devices, with dual-wavelength probes attached to the third-eyelid and ear recorded arterial peripheral oxygen-haemoglobin saturation (SpO2) at pre-determined time points, concurrently with measurements of arterial oxygen-haemoglobin saturation (SaO2), from drawn blood samples, by a benchtop AVOXimeter 4000 co-oximeter (reference method). Reliability of the Nonin and Masimo devices was evaluated using the Bland-Altman and the area root mean squares (ARMS) methods. Clinical performance of the devices was evaluated for their ability to accurately detect clinical hypoxemia using receiver operating characteristic (ROC) curves and measures of sensitivity, specificity, and positive and negative predictive values. Trending ability of the devices was assessed by calculating concordance rates from four-quadrant plots. RESULTS: Only the Nonin device with transflectance probe attached to the third-eyelid provided reliable SpO2 measurements across the 70 to 100% saturation range (bias - 1%, precision 4%, ARMS 4%). Nonin and Masimo devices with transflectance probes attached to the third-eyelid both had high clinical performance at detecting clinical hypoxaemia [area under the ROC curves (AUC): 0.93 and 0.90, respectively]. However, the Nonin and Masimo devices with transmission probes attached to the ear were unreliable and provided only moderate clinical performance. Both Nonin and Masimo devices, at both measurement sites, had concordance rates lower than the recommended threshold of ≥ 90%, indicating poor trending ability. CONCLUSIONS: The overall assessment of reliability, clinical performance and trending ability indicate that the Nonin device with transflectance probe attached to the third-eyelid is best suited for monitoring of blood oxygenation in immobilised rhinoceros. The immobilisation procedure may have affected cardiovascular function to an extent that it limited the devices' performance.

A prospective observational study evaluating two patient immobilisation methods in lung stereotactic radiotherapy.

PURPOSE: The main objective of this study was to assess inter- and intrafraction errors for two patient immobilisation devices in the context of lung stereotactic body radiation therapy: a vacuum cushion and a simple arm support. MATERIALS AND METHODS: Twenty patients who were treated with lung stereotactic body radiation therapy in supine position with arms above their head were included in the study. Ten patients were setup in a vacuum cushion (Bluebag™, Elekta) and ten other patients with a simple arm support (Posirest™, Civco). A pretreatment four-dimensional cone-beam computed tomography and a post-treatment three-dimensional cone-beam computed tomography were acquired to compare positioning and immobilisation accuracy. Based on a rigid registration with the planning computed tomography on the spine at the target level, translational and rotational errors were reported. RESULTS: The median number of fractions per treatment was 5 (range: 3-10). Mean interfraction errors based on 112 four-dimensional cone-beam computed tomographies were similar for both setups with deviations less than or equal to 1.3mm in lateral and vertical direction and 1.2° in roll and yaw. For longitudinal translational errors, mean interfraction errors were 0.7mm with vacuum cushion and -3.9mm with arm support. Based on 111 three-dimensional cone-beam computed tomographies, mean lateral, longitudinal and vertical intrafraction errors were -0.1mm, -0.2mm and 0.0mm respectively (SD: 1.0, 1.2 and 1.0mm respectively) for the patients setup with vacuum cushion, and mean vertical, longitudinal and lateral intrafraction errors were -0.3mm, -0.7mm and 0.1mm respectively (SD: 2.3, 1.8 and 1.4mm respectively) for the patients setup with arm support. Intrafraction errors means were not statistically different between both positions but standard deviations were statistically larger with arm support. CONCLUSION: The results of our study showed similar inter and intrafraction mean deviations between both positioning but a large variability in intrafraction observed with arm support suggested a more accurate immobilization with vacuum cushion.

Air inflow into vacuum-type immobilization devices impacts setup errors.

We aimed to determine the impact of air inflow into vacuum-type immobilization devices (VIDs) on setup errors. We assigned 70 patients undergoing radiotherapy for head and neck cancer to groups V (n = 34) or N (n = 36) according to whether the VIDs were deflated weekly or not deflated during treatment, respectively. We calculated systematic errors (Σ) as the standard deviations (SDs) of mean errors, and random errors (σ) as the root mean square of SDs in each patient. We compared overall means (µ), SDs (SDoverall), random errors and systematic errors. We also measured temporary pressure changes in VIDs to determine the influence of pressure changes in VIDs on setup errors. The µ was within 0.20 mm and 0.2° in both groups, whereas SDoverall significantly differed between them. The SDoverall differed the most in the Roll axes of groups N (0. 87°) and V (0.58°). The Σ and σ values were lower in all axes of group V than in group N. Despite the initial deflation target of - 70 kPa, the pressure in VIDs reached - 5 kPa at the end of treatment. However, weekly deflation apparently maintained pressure at - 20 kPa. Effective pressure control in VIDs can reduce patient-by-patient variation and improve setup reproducibility for individual patients, consequently resulting in small variations among overall setup errors.

Environmentally friendly splints for limb immobilisation: a systematic review.

INTRODUCTION: Climate change is estimated to be the biggest global health threat of the 21st century, and has prompted calls to move away from processes in healthcare associated with high energy consumption and greenhouse gas emission. In musculoskeletal medicine, splints are widely used for limb immobilisation. These have typically been made from single-use materials such as gypsum, although in recent years purportedly environmentally friendly splints have been designed. In this systematic review, we set out to assess the clinical effectiveness of all commercially available environmentally friendly splinting materials, including Woodcast®. METHODS: The AMED (Allied and Complementary Medicine Database), CINAHL® (Cumulative Index to Nursing and Allied Health Literature), Cochrane Central Register of Controlled Trials, Embase®, Emcare® and MEDLINE® databases were searched to identify studies assessing the clinical effectiveness of biodegradable and environmentally friendly splints prior to paper review and data extraction. Formal quantitative synthesis was not possible owing to the substantial heterogeneity in the study designs and outcome measures. RESULTS: Six papers met the inclusion criteria, all investigating one particular splint material (Woodcast®). One was a case series, two were cohort studies and three were randomised controlled trials. Primary outcome measures were heterogeneous but the environmentally friendly splints were generally equivalent to traditional splint materials. Studies were mostly at a high risk of bias. CONCLUSIONS: There is limited research assessing 'green' splints in practice although the data suggest similarity with existing materials and no substantial safety concerns. Further scrutiny of the clinical effectiveness and environmental credentials of such splints is also required.

MRgFUS ablation of a recurrent tenosynovial giant cell tumor in the foot using ExAblate 2100 system in combination with patient immobilization device.

INTRODUCTION: Magnetic Resonance-guided Focused Ultrasound (MRgFUS) treatment for certain anatomy locations can be extremely challenging due to patient positioning and potential motion. This present study describes the treatment of a recurrent tenosynovial giant cell tumor of the plantar forefoot using the ExAblate 2100 system in combination with patient immobilization device. METHODS: Prior to the treatment, several patient immobilization devices were investigated. Vacuum cushions were selected and tested for safety and compatibility with the treatment task and the MR environment. RESULTS: During the treatment, one vacuum cushion immobilized the patient's right leg in knee flexion and allowed the bottom of the foot to be securely positioned on the treatment window. Another vacuum cushion supported the patient upper body extended outside the scanner bore. 19 sonications were successfully executed. The treatment was judged to be successful. No immediate complications were observed. CONCLUSIONS: MRgFUS treatment of a recurrent tenosynovial giant cell tumor of the right plantar forefoot was successful with the use of patient immobilization vacuum cushions. IMPLICATIONS FOR PRACTICE: The immobilization system could be utilized to aid future MRgFUS treatment of lesions in challenging anatomic locations. Various sizes of the vacuum cushions are available to potentially better accommodate other body parts and treatment configurations.

Randomized self-controlled study comparing open-face vs. closed immobilization masks in fractionated cranial radiotherapy.

PURPOSE: To compare patient discomfort and immobilisation performance of open-face and closed immobilization masks in cranial radiotherapy. MATERIAL AND METHODS: This was a single-center randomized self-controlled clinical trial. At CT simulation, an open-face and closed mask was made for each patient and treatment plans with identical dose prescription were generated for each mask. Patients were randomised to start treatment with an open-face or closed mask. Masks were switched halfway through the treatment course; every patient was their own control. Patients self-reported discomfort, anxiety and pain using the visual analogue scale (VAS). Inter- and intrafraction set-up variability was measured with planar kV imaging and a surface guided radiotherapy (SGRT) system for the open-face masks. RESULTS: 30 patients with primary or metastatic brain tumors were randomized - 29 completed radiotherapy to a median total dose of 54 Gy (range 30-60 Gy). Mean discomfort VAS score was significantly lower with open-face masks (0.5, standard deviation 1.0) vs. closed masks (3.3, standard deviation 2.9), P < 0.0001. Anxiety and pain VAS scores were significantly lower with open-face masks (P < 0.0001). Closed masks caused more discomfort in infraorbital (P < 0.001) and maxillary (P = 0.02) areas. Two patients and 27 patients preferred closed or open-face masks, respectively. Interfraction longitudinal shifts and roll and yaw rotations were significantly smaller and lateral shifts were significantly larger with closed masks in combination with the laser system (P < 0.05) compared to open masks in combination with a SGRT system. Intrafraction variability did not differ between the masks. CONCLUSIONS: Open-face masks are associated with decreased patient discomfort without compromising patient positioning and immobilisation accuracy.

AAPM Task Group 334: A guidance document to using radiotherapy immobilization devices and accessories in an MR environment.

Use of magnetic resonance (MR) imaging in radiation therapy has increased substantially in recent years as more radiotherapy centers are having MR simulators installed, requesting more time on clinical diagnostic MR systems, or even treating with combination MR linear accelerator (MR-linac) systems. With this increased use, to ensure the most accurate integration of images into radiotherapy (RT), RT immobilization devices and accessories must be able to be used safely in the MR environment and produce minimal perturbations. The determination of the safety profile and considerations often falls to the medical physicist or other support staff members who at a minimum should be a Level 2 personnel as per the ACR. The purpose of this guidance document will be to help guide the user in making determinations on MR Safety labeling (i.e., MR Safe, Conditional, or Unsafe) including standard testing, and verification of image quality, when using RT immobilization devices and accessories in an MR environment.

Comparison of a new immobilization method using a reusable 3-point fixation cylinder system and bite-block type immobilization methods in veterinary radiotherapy.

In veterinary radiotherapy, highly reproducible immobilization is important for accurate irradiation. Consequently, we developed a new reusable head-immobilization method for dogs using cylinders. This study aimed to compare the accuracy of our novel immobilization method using cylinders with that of bite-block type immobilization methods. Three immobilization methods were compared: bite-block only, bite-block combined with torso immobilization, and immobilization using cylinders. Five beagles with canine teeth underwent CT five times for each of the three immobilization methods. One beagle without canine teeth underwent CT 15 times using each method. Three maxillary landmarks (maxillary incisor, frontal sinus, and occipital bone) and one mandibular landmark (mandibular incisor) were established, and the errors in each immobilization method were measured. For all head landmarks, the error in the immobilization method using cylinders was the most reproducible, with the smallest errors. No significant differences were observed in the time required for immobilization. Although there were limitations (such as the use of dogs from a single breed, a single episode of anesthesia, no disassembly of the immobilization system between scans, and the same person performing the positioning on the same day), we found our new reusable immobilization method using cylinders was the most accurate among the three compared methods. This was a proof-of-principle study to evaluate head immobilization using cylinders, and further investigations are needed to confirm its clinical utility.

Postoperative immobilization using a short-arm cast in the semisupination position is appropriate after arthroscopic triangular fibrocartilage complex foveal repair.

AIMS: The aim of this study was to assess and compare active rotation of the forearm in normal subjects after the application of a short-arm cast (SAC) in the semisupination position and a long-arm cast (LAC) in the neutral position. A clinical study was also conducted to compare the functional outcomes of using a SAC in the semisupination position with those of using a LAC in the neutral position in patients who underwent arthroscopic triangular fibrocartilage complex (TFCC) foveal repair. METHODS: A total of 40 healthy right-handed volunteers were recruited. Active pronation and supination of the forearm were measured in each subject using a goniometer. In the retrospective clinical study, 40 patients who underwent arthroscopic foveal repair were included. The wrist was immobilized postoperatively using a SAC in the semisupination position (approximately 45°) in 16 patients and a LAC in 24. Clinical outcomes were assessed using grip strength and patient-reported outcomes. The degree of disability caused by cast immobilization was also evaluated when the cast was removed. RESULTS: Supination was significantly more restricted with LACs than with SACs in the semisupination position in male and female patients (p < 0.001 for both). However, pronation was significantly more restricted with SACs in the semisupination position than with LACs in female patients (p = 0.003) and was not significantly different in male patients (p = 0.090). In the clinical study, both groups showed improvement in all parameters with significant differences in grip strength, visual analogue scale scores for pain, modified Mayo Wrist Score, the Disability of the Arm, Shoulder, and Hand (DASH) score, and the Patient-Rated Wrist Evaluation (PRWE) score. No significant postoperative differences were noted between LACs and SACs in the semisupination position. However, the disability caused by immobilization in a cast was significantly higher in patients who had a LAC on the dominant hand (p < 0.001). CONCLUSION: We found that a SAC in the semisupination position is as effective as a LAC in restricting pronation of the forearm. In addition, postoperative immobilization with a SAC in the semisupination position resulted in comparable pain scores and functional outcomes to immobilization with a LAC after TFCC foveal repair, with less restriction of daily activities. Therefore, we recommend that surgeons consider using a SAC in the semisupination position for postoperative immobilization following TFCC foveal repair for dorsal instability of the distal radioulnar joint. Cite this article: Bone Joint J 2022;104-B(2):249-256.

Compare of Interfractional Setup Reproducibility Between Vacuum-Lock Bag and Thermoplastic Mask in Radiotherapy for Breast Cancer.

Background: This study aimed to analyze the difference of setup reproducibility between Vacuum-lock bag and Thermoplastic mask in the radiotherapy for breast cancer. Methods: A total of 100 invasive breast carcinoma patients were collected, among whom 50 patients were immobilized with Vacuum-lock bag (VB group), and the other 50 patients were immobilized with Thermoplastic mask (TM group). Set up reproducibility in different axes and comfort levels between two groups at three treatment progress points during the radiation therapy were collected and analyzed. Results: The linear regression model showed that fixed device was an independent factor of radiotherapy setup error (SE). Further subgroup analysis based on different axes showed that the SE caused by the fixed device was obvious in all directions. The comfort level in the VB group was significantly larger than that in the TM group at the beginning of treatment, reduced as the treatment progress going on, and finally disappeared within three weeks. Conclusions: Thermoplastic mask could significantly reduce positioning errors in the radiotherapy of breast cancer. Although more discomfort was found in the TM group, it could be eliminated as the treatment progresses.

Fetally-injected drugs for immobilization and analgesia do not modify fetal brain development in a rabbit model.

OBJECTIVE: During fetal surgery, fetuses receive medication (atropine-fentanyl-curare) to prevent fetal pain, movement and bradycardia. Although essential there has been no detailed review of potential side effects. Herein we aimed to assess the effects of this medication cocktail on fetal brain development in a rabbit model. METHODS: Pregnant does underwent laparotomy at 28 days of gestation. Two pups of each horn were randomized to an ultrasound guided injection with medication (atropine-cisatracurium-fentanyl, as clinically used) or saline (sham). The third pup was used as control. At term, does were delivered by cesarean. Outcome measures were neonatal biometry, neuromotoric functioning and neuro-histology (neuron density, synaptic density and proliferation). RESULTS: Maternal vital parameters remained stable during surgery. Fetal heart rates did not differ before and after injection, and were comparable for the three groups. At birth, neonatal body weights and brain-to-body weight ratios were also comparable. Both motor and sensory neurobehavioral scores were comparable. There were no differences in neuron density or proliferation. Sham pups, had a lower synaptic density in the hippocampus as compared to the medication group, however there was no difference in the other brain areas. CONCLUSION: In the rabbit model, fetal medication does not appear to lead to short-term neurocognitive effects.

Vacuum mattress or long spine board: which method of spinal stabilisation in trauma patients is more time consuming? A simulation study.

BACKGROUND: Spinal stabilisation is recommended for prehospital trauma treatment. In Germany, vacuum mattresses are traditionally used for spinal stabilisation, whereas in anglo-american countries, long spine boards are preferred. While it is recommended that the on-scene time is as short as possible, even less than 10 minutes for unstable patients, spinal stabilisation is a time-consuming procedure. For this reason, the time needed for spinal stabilisation may prevent the on-scene time from being brief. The aim of this simulation study was to compare the time required for spinal stabilisation between a scoop stretcher in conjunction with a vacuum mattress and a long spine board. METHODS: Medical personnel of different professions were asked to perform spinal immobilizations with both methods. A total of 172 volunteers were immobilized under ideal conditions as well as under realistic conditions. A vacuum mattress was used for 78 spinal stabilisations, and a long spinal board was used for 94. The duration of the procedures were measured by video analysis. RESULTS: Under ideal conditions, spinal stabilisation on a vacuum mattress and a spine board required 254.4 s (95 % CI 235.6-273.2 s) and 83.4 s (95 % CI 77.5-89.3 s), respectively (p < 0.01). Under realistic conditions, the vacuum mattress and spine board required 358.3 s (95 % CI 316.0-400.6 s) and 112.6 s (95 % CI 102.6-122.6 s), respectively (p < 0.01). CONCLUSIONS: Spinal stabilisation for trauma patients is significantly more time consuming on a vacuum mattress than on a long spine board. Considering that the prehospital time of EMS should not exceed 60 minutes and the on-scene time should not exceed 30 minutes or even 10 minutes if the patient is in extremis, based on our results, spinal stabilisation on a vacuum mattress may consume more than 20 % of the recommended on-scene time. In contrast, stabilisation on a spine board requires only one third of the time required for that on a vacuum mattress. We conclude that a long spine board may be feasible for spinal stabilisation for critical trauma patients with timesensitive life threatening ABCDE-problems to ensure the shortest possible on-scene time for prehospital trauma treatment, not least if a patient has to be rescued from an open or inaccessible terrain, especially that with uneven overgrown land.

Therapeutic Rationale for Endotoxin Removal with Polymyxin B Immobilized Fiber Column (PMX) for Septic Shock.

Endotoxin removal therapy with polymyxin B immobilized fiber column (PMX) has been clinically applied for sepsis and septic shock patients since 1994. The effectiveness and usefulness of this therapy have been demonstrated for more than a quarter of a century. However, a documented survival benefit has not yet been demonstrable in a large, multicenter, randomized and controlled trial. Following the findings derived from a large sepsis clinical trial with PMX in North America, a new trial is ongoing to determine if PMX has a long-term survival benefit when administered to septic patients. Another approach to support a survival benefit from intervention with PMX is to utilize a detailed analysis available from a large clinical data base. The endotoxin adsorption capacity of PMX columns in vitro and the effectiveness of PMX columns can be further demonstrable in animal models. The capability of PMX and details of its mechanism of action to intervene in the sepsis cascade and impede organ dysfunction in septic patients is not fully understood. The surface antigen expression in monocytes and neutrophils are improved after PMX therapy. Immunomodulatory effects as a result of endotoxin removal and/or other mechanisms of action have been suggested. These effects and other potential immune effects may explain some of the improved effects upon organ dysfunction of sepsis and septic shock patients. Endotoxemia may be involved in the pathophysiology of other diseases than sepsis. A rapid diagnostic method to detect and target endotoxemia could allow us to practice precision medicine and expand the clinical indications of endotoxin removal therapy.

Rehabilitation regimen for non-surgical treatment of Achilles tendon rupture: A systematic review and meta-analysis of randomised controlled trials.

OBJECTIVES: To compare re-rupture rate, functional and quality-of-life outcomes, return to sports and work, complications, and resource use in patients treated non-surgically with different rehabilitation regimens for Achilles tendon rupture. DESIGN: Systematic review and meta-analysis. METHODS: We performed a systematic literature search in PubMed, Embase, Scopus and the Cochrane Library through May 2020 to identify randomized controlled trials (RCTs) that included patients treated non-surgically for Achilles tendon rupture. All analyses were stratified according to rehabilitation protocols. RESULTS: Eight RCTs with a total of 978 patients were included. There was no significant difference about re-rupture rate (P=0.38), return to sports (P=0.85) and work (P=0.33), functional outcome (P=0.34), quality of life (P=0.50), and complication rate (P=0.29) between early weight bearing with functional ankle motion and traditional ankle immobilisation with non-weight bearing. Similarly, no significant difference in re-rupture rate (P=0.88), return to sports (P=0.45) and work (P=0.20), functional outcome (P=0.26), and complication rate (P=0.49) was seen between ankle immobilisation with non-weight bearing and early weight bearing without functional ankle motion. CONCLUSIONS: Traditional ankle immobilisation with non-weight bearing was not found to be superior to early weight bearing with or without functional ankle motion for patients treated non-surgically for Achilles tendon rupture. Clinicians may consider early weight bearing in functional brace as a safe and cost-effective alternative to non-weight bearing with plaster casting.

Intra-fractional patient setup error during fractionated intracranial stereotactic irradiation treatment of patients wearing medical masks: comparison with and without bite block during COVID-19 pandemic.

The immobilization of patients with a bite block (BB) carries the risk of interpersonal infection, particularly in the context of pandemics such as COVID-19. Here, we compared the intra-fractional patient setup error (intra-SE) with and without a BB during fractionated intracranial stereotactic irradiation (STI). Fifteen patients with brain metastases were immobilized using a BB without a medical mask, while 15 patients were immobilized without using a BB and with a medical mask. The intra-SEs in six directions (anterior-posterior (AP), superior-inferior (SI), left-right (LR), pitch, roll, and yaw) were calculated by using cone-beam computed tomography images acquired before and after the treatments. We analyzed a total of 53 and 67 treatment sessions for the with- and without-BB groups, respectively. A comparable absolute mean translational and rotational intra-SE was observed (P > 0.05) in the AP (0.19 vs 0.23 mm with- and without-BB, respectively), SI (0.30 vs 0.29 mm), LR (0.20 vs 0.29 mm), pitch (0.18 vs 0.27°), roll (0.23 vs 0.23°) and yaw (0.27 vs 22°) directions. The resultant planning target volume (PTV) margin to compensate for intra-SE was <1 mm. No statistically significant correlation was observed between the intra-SE and treatment times. A PTV margin of <1 mm was achieved even when patients were immobilized without a BB during STI dose delivery.

Effect of Surgical Mask on Setup Error in Head and Neck Radiotherapy.

PURPOSE: With the widespread prevalence of Corona Virus Disease 2019 (COVID-19), cancer patients are suggested to wear a surgical mask during radiation treatment. In this study, cone beam CT (CBCT) was used to investigate the effect of surgical mask on setup errors in head and neck radiotherapy. METHODS: A total of 91 patients with head and neck tumors were selected. CBCT was performed to localize target volume after patient set up. The images obtained by CBCT before treatment were automatically registered with CT images and manually fine-tuned. The setup errors of patients in 6 directions of Vrt, Lng, Lat, Pitch, Roll and Rotation were recorded. The patients were divided into groups according to whether they wore the surgical mask, the type of immobilization mask used and the location of the isocenter. The setup errors of patients were calculated. A t-test was performed to detect whether it was statistically significant. RESULTS: In the 4 groups, the standard deviation in the directions of Lng and Pitch of the with surgical mask group were all higher than that in the without surgical mask group. In the head-neck-shoulder mask group, the mean in the Lng direction of the with surgical mask group was larger than that of the without surgical mask group. In the lateral isocenter group, the mean in the Lng and Pitch directions of the with surgical mask group were larger than that of the without surgical mask group. The t-test results showed that there was significant difference in the setup error between the 2 groups (p = 0.043 and p = 0.013, respectively) only in the Lng and Pitch directions of the head-neck-shoulder mask group. In addition, the setup error of 6 patients with immobilization open masks exhibited no distinguished difference from that of the patients with regular immobilization masks. CONCLUSION: In the head and neck radiotherapy patients, the setup error was affected by wearing surgical mask. It is recommended that the immobilization open mask should be used when the patient cannot finish the whole treatment with a surgical mask.

Two Bacillus isolates recovered from a radiation therapy facility differ greatly in their ability to attach to four immobilization masks.

BACKGROUND: Thermoplastic immobilization masks used during radiation therapy treatment have been shown to harbor several different types of bacteria. Recovered bacteria included Staphylococcus aureus, Enterococcus species, Gram-negative rods, coagulase-negative staphylococci, and several different Bacillus species. Two of the recovered Bacillus bacteria were examined for their ability to attach to and survive over time on patient head-only masks from four different manufacturers. B. halosaccharovorans was recovered from a treatment facility's water bath while B. cereus was recovered from a patient mask in the same facility. Bacillus bacteria were chosen for this study due to their capability to form dormant spores. METHODS: Inoculums containing either B. halosaccharovorans or B. cereus bacteria were seeded onto predesignated areas of each test mask. Masks were subsequently sampled at intervals of 1-h, 1 week, 2 weeks, 3 weeks, and 4 weeks. Recovered bacterial numbers at each sampling interval were determined using the direct plate count method. Spore stains were made of both bacterial isolates and number of detected spores were enumerated. RESULTS: B. halosaccharovorans attached to each mask type after a 1-h contact time at a number 3X greater than B. cereus. B. halosaccharovorans was also recovered at a number 8.5X greater than B. cereus after 4 weeks. Variation was seen in the attachment capability of each bacterium on tested mask types. Both bacilli were recovered from all 4 masks at each sampling interval including week 4. Examination of spore stains of each bacteria demonstrated nearly a 25:1 ratio of B. halosaccharovorans spores over B. cereus. DISCUSSION: The large variation seen between B. halosaccharovorans and B. cereus capability to attach to each of the four tested masks is revealing, especially when it is combined with determined spore numbers. It suggests that spores play a role in mediating their attachment to mask surfaces. Moreover, the recovery of both bacteria from stored masks after 4 weeks indicates a continued presence of dormant spores since growth-supportive nutrients are lacking. It also implies the potential for their transfer to a patient wearing a contaminated mask during a treatment session. CONCLUSION: The demonstrated ability of these two Bacillus bacteria to attach to and reside on patient masks presents a dilemma. Routine cleaning with approved disinfectants may not be sufficient to eliminate dormant spores on masks surfaces. This matter requires further investigation. For now, a small modification to the routine mask cleaning procedure before its application may help to reduce the possibility of spore transfer.

Patient perspectives on frame versus mask immobilization for gamma knife stereotactic radiosurgery.

PURPOSE: To assess patient experiences and perspectives following Gamma Knife (GK) stereotactic radiosurgery (SRS) using frame versus mask immobilization. METHODS: Patients who received GK-SRS using both frame and mask immobilization were included in this study. One-on-one semi-structured interviews, led by a third-party expert, were used to gain insight into the patient experience. To reduce memory bias of either immobilization device, patients underwent the interview at their follow-up appointment. Initial assessment of patient transcriptions was completed by one study staff; a second member reviewed transcripts for thematic saturation. All interviews were independently coded for themes to minimize interpretation bias. RESULTS: Fifteen patients were consented; 12 were successfully interviewed (3 lost due to deteriorating health status). Interviews ranged from 30 to 60 min in duration. The most common patient concern regarding the frame was pain (9 patients), while the primary concerns with the mask system were the ability to remain still (6 patients) and claustrophobia (4 patients). Eleven patients chose the mask as their preferred choice in terms of their overall experience. Two themes emerged during the interviews that spoke to patient satisfaction with each process: unexpected pain with frame placement; and tightness experienced while wearing the mask during treatment. CONCLUSIONS: From the patient perspective there was overwhelming agreement that the mask was the preferred choice for GK-SRS. The patient experience could be improved by enhanced education to better prepare patients on what to expect during the frame placement and mask treatment processes.