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.

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.

Comparison of suture-button and screw fixation in the treatment of ankle syndesmotic injuries: Cohort study protocol.

BACKGROUND: Syndesmotic injuries account for a significant number of ankle injuries. There is no consensus regarding the recommended method of treatment. The purpose of this study was to evaluate: METHODS:: This study was performed and reported in accordance with the Strengthening the Reporting of Observational studies in Epidemiology checklist. The records of 200 patients with ankle fractures who had undergone surgical treatment in our clinics between January 2014 and January 2018 were retrospectively investigated. This retrospective cohort study was approved by the institutional review board in the 2nd Hospital of Jilin University. The primary outcome measure was the American Orthopaedic Foot and Ankle Society ankle-hindfoot scale and the Foot Function Index. Secondary outcome measures included visual analog scale score, complications, range of movement of ankle, reoperations, and radiologic outcomes. For statistical comparison of the clinical and radiologic findings between the 2 groups, we used SPSS, version 21.0 (SPSS, Chicago, IL), statistical software. P Values of < .05 were considered statistically significant. CONCLUSION: The hypothesis was that the SB technique would achieve better functional outcomes as compared to the syndesmotic screw technique after surgery. TRIAL REGISTRATION: This study protocol was registered in Research Registry (researchregistry5793).

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.

Evaluating Canadian Radiation Therapists and UK Therapeutic Radiographers' Experiences and Opinions of a Safety Strap to Secure Patients during Radiotherapy.

INTRODUCTION: A serious patient safety incident at a cancer centre in Ontario, Canada, saw a patient fall from an elevated treatment couch. A regional investigation recommended the use of a securing safety strap. The authors evaluate the value of the strap through the experiences of the radiation therapists' who use it. A secondary aim is to explore the potential for using a securing safety strap with UK therapeutic radiographers. METHODS: A two-stage design was guided by an evidence-based practice framework. Stage one used a questionnaire to capture treating radiation therapists' experiences and opinions of the strap at a single cancer centre. Quantitative data were analysed descriptively and free-text data via a content analysis. Stage two used semistructured interviews with thematic analysis to explore views of three UK therapeutic radiographers. RESULTS: Twenty-five of approximately 130 eligible staff responded to the Canadian questionnaire. Of the respondents, 24% (n = 6) 'strongly disagreed', 28% (n = 7) 'agreed' and 48% (n = 12) 'neither agreed nor disagreed' that they would recommend the strap to other departments. Most of the respondents think strap use should be at the staffs' discretion, with patients with dementia/cognitive impairment ranked as the group benefiting most. Ninety-two percent (n = 23) of respondents confirmed that patients sometimes refuse the strap. Themes arising from stage two interviews are as follows: patient benefit (use for select patients only); patient safety versus control (restraint); and practical implementation issues. CONCLUSION: The policy of universal use of the strap should be reviewed. Those who use it are equivocal about its value and feel it should be reserved for select patients at the treating professional's discretion. Full evaluation of the effectiveness and acceptability of the device for different patients may promote both staff enthusiasm towards the device and evidence-based practice. Adequate resources are required to evaluate implementation of such safety initiatives.

Indentation marks, skin temperature and comfort of two cervical collars: A single-blinded randomized controlled trial in healthy volunteers.

BACKGROUND: Collar-related pressure ulcers (CRPU) are a problem in trauma patients with a suspicion of cervical cord injury patients. Indentation marks (IM), skin temperature (Tsk) and comfort could play a role in the development of CRPU. Two comparable cervical collars are the Stifneck® and Philadelphia®. However, the differences between them remain unclear. AIM: To determine and compare occurrence and severity of IM, Tsk and comfort of the Stifneck® and Philadelphia® in immobilized healthy adults. METHODS: This single-blinded randomized controlled trial compared two groups of immobilized participants in supine position for 20 min. RESULTS: All participants (n = 60) generated IM in at least one location in the observed area. Total occurrence was higher in the Stifneck®-group (n = 95 versus n = 69; p = .002). Tsk increased significantly with 1.0  °C in the Stifneck®-group and 1.3 °C in the Philadelphia®-group (p = .024). Comfort was rated 3 on a scale of 5 (p = .506). CONCLUSION: The occurrence of IM in both groups was high. In comparison to the Stifneck®, fewer and less severe IM were observed from the Philadelphia®. The Tsk increased significantly with both collars; however, no clinical difference in increase of Tsk between them was found. The results emphasize the need for a better design of cervical collars regarding CRPU.

Subluxación atloaxoidea no traumática: síndrome de Grisel / Nontraumatic atlantoaxial subluxation: Grisel síndrome

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Comparison of thermoplastic masks and knee wedge as immobilization devices for image-guided pelvic radiation therapy using Cone Beam Computed Tomography.

INTRODUCTION: Pelvic radiotherapy is generally performed with the use of an immobilization and positioning device. AIM AND OBJECTIVE: The objective of the study was to ascertain and compare setup errors between the two positioning devices. MATERIALS AND METHODS: A total of 35 patients of stage II and III cervical cancers were enrolled in the study and divided into two groups, one using knee wedge and the other using thermoplastic pelvic mask as an immobilization device. Radiation was planned by four field box conformal technique. The random and systematic setup errors were then calculated for each patient in both the groups in the mediolateral (ML), superoinferior (SI), and anteroposterior (AP) directions. RESULTS: The translational mean setup variation in the lateral, longitudinal, and vertical direction is 0.17 ± 0.24, -0.12 ± 0.48, and -0.18 ± 0.27 cm for thermoplastic pelvic mask and -0.03 ± 0.26, -0.04 ± 0.48, and -0.09 ± 0.37 cm for knee wedge, respectively. The systematic setup error and random errors were 0.24, 0.48, 0.27 cm and 0.31, 0.60, and 0.40 cm for thermoplastic mask and 0.26, 0.48, and 0.37 cm and 0.38, 0.37, and 0.45 cm for knee wedge in ML, SI, and AP axis, respectively. The one way analysis of variance test was applied to compare the setup errors in between the three axes for both the immobilization devices. To compare the positioning accuracy of thermoplastic mask and knee wedge, Student's t-test was applied. Both the tests were found to be insignificant (P value > 0.05). CONCLUSION: Thermoplastic mask and knee wedge are equally effective as immobilization devices for treating cervical cancers with conformal techniques.

Jaw Elevation Device: Tool for Neck Immobilization to Facilitate Recovery in Endovascular Thrombectomy via Transcervical Access.

BACKGROUND: Acute stroke resolution via endovascular thrombectomy requires transcarotid access when transfemoral access is not possible. Although postoperative complications such as cervical hematoma and airway compression have been reported, an appropriate postprocedural management is largely unknown yet. We aim to provide new insights and learning points from our experience using the Jaw Elevation Device (JED) as a tool to facilitate recovery post surgery. CASE DESCRIPTION: A 79-year-old female underwent endovascular thrombectomy via transcervical, transcarotid access for a left internal carotid artery occlusion. No intraprocedural complications were reported. After successful thrombectomy, manual compression was applied in the carotid artery, and to achieve neck immobilization a JED was used for 4 hours after the procedure. No complications occurred. CONCLUSIONS: JED appears to be a reasonable option to facilitate patient recovery due to its capacity to maintain the airway, provide mild compression for hemostasis, and prevent cervical hematoma through a comfortable neck immobilization.

Repositioning accuracy of a novel thermoplastic mask for head and neck cancer radiotherapy.

PURPOSE: The aim of this study was to assess the reproducibility of patient shoulder position immobilized with a novel and innovative prototype mask (E-Frame, Engineering System). METHODS: The E-frame mask fixes both shoulders and bisaxillary regions compared with that of a commercial mask (Type-S, CIVCO). Thirteen and twelve patients were immobilized with the Type-S and E-Frame mask systems, respectively. For each treatment fraction, cone-beam CT (CBCT) images of the patient were acquired and retrospectively analyzed. The CBCT images were registered to the planning CT based on the cervical spine, and then the displacements of the acromial extremity of the clavicle were measured. RESULTS: The systematic and random errors between the two mask systems were evaluated. The differences of the systematic errors between the two mask systems were not statistically significant. The mean random errors in the three directions (AP, SI and LR) were 2.7 mm, 3.1 mm and 1.5 mm, respectively for the Type-S mask, and 2.8 mm 2.5 mm and 1.4 mm, respectively for the E-Frame mask. The random error of the E-Frame masks in the SI direction was significantly smaller than that of the Type-S. The number of cases showing displacements exceeding 10 mm in the SI direction for at least one fraction was eight (61% of 13 cases) and three (25% of 12 cases) for Type-S and E-Frame masks, respectively. CONCLUSIONS: The E-Frame masks reduced the random displacements of patient's shoulders in the SI direction, effectively preventing large shoulder shifts that occurred frequently with Type-S masks.