A nomogram to determine required seed air kerma strength in planar 131 Cesium permanent seed implant brachytherapy

Purpose: Intraoperatively implanted Cesium-131 ( 131 Cs) permanent seed brachytherapy is used to deliver highly localized re-irradiation in recurrent head and neck cancers. A single planar implant of uniform air kerma strength (AKS) seeds and 10 mm seed-to-seed spacing is used to deliver the prescribed dose to a point 5 mm or 10 mm perpendicular to the center of the implant plane. Nomogram tables to quickly determine the required AKS for rectangular and irregularly shaped implants were created and dosimetrically verified. By eliminating the need for a full treatment planning system plan, nomogram tables allow for fast dose calculation for intraoperative re-planning and for a second check method. Material and methods: TG-43U1 recommended parameters were used to create a point-source model in MATLAB. The dose delivered to the prescription point from a single 1 U seed at each possible location in the implant plane was calculated. Implant tables were verified using an independent seed model in MIM Symphony LDR™. Implant tables were used to retrospectively determine seed AKS for previous cases: three rectangular and three irregular. Results: For rectangular implants, the percent difference between required seed AKS calculated using MATLAB and MIM was at most 0.6%. For irregular implants, the percent difference between MATLAB and MIM calculations for individual seed locations was within 1.5% with outliers of less than 3.1% at two distal locations (10.6 cm and 8.8 cm), which have minimal dose contribution to the prescription point. The retrospectively determined AKS for patient implants using nomogram tables agreed with previous calculations within 5% for all six cases. Conclusions: Nomogram tables were created to determine required AKS per seed for planar uniform AKS 131 Cs implants. Comparison with the treatment planning system confirms dosimetric accuracy that is acceptable for use as a second check or for dose calculation in cases of intraoperative re-planning

Evaluating CPB's published GDP growth forecasts; a comparison with individual and pooled VAR based forecasts

We compare the accuracy of our published GDP growth forecasts from our large macro model, SAFFIER, to those produced by VAR based models using both classical and Bayesian estimation techniques. We employ a data driven methodology for selecting variables to include in our VAR models and we find that a randomly selected classical VAR model performs worse in most cases than the Bayesian equivalent, which performs worse than our published forecasts in most cases. However, when we pool forecasts across many VARs we can produce more accurate forecasts than we published. A review of the literature suggests that forecast accuracy is likely irrelevant for the non-forecasting activities the model is used for at CPB because they are fundamentally different activities.

Early adoption of transoral robotic surgical program: preliminary outcomes.

OBJECTIVE: The objective of this study is to demonstrate the feasibility and safety of establishing a transoral robotic surgical (TORS) program in the post-Food and Drug Administration (FDA) approval setting. Early outcomes are compared with the previously reported results of pioneering centers. STUDY DESIGN: Clinical data from a prospective TORS study. SETTING: Academic university institution. SUBJECTS AND METHODS: Sixty-one patients treated with 63 TORS procedures. Main outcome measures: intraoperative times, margin status, complications, time to diet, and percutaneous endoscopic gastrostomy (PEG) tube retention rate. The authors also report oncologic outcomes on their first 30 patients. RESULTS: The spectrum of subsites included tongue base, tonsil, parapharyngeal space, retromolar trigone, supraglottis, and posterior pharyngeal wall. Surgical console time averaged 79 ± 53 minutes. After re-resection of 4 patients, final negative margin status was 94% (50/53). A subset of 30 patients with squamous cell carcinoma reaching an average of 18 months of follow-up had a local regional control rate of 97% with a disease-free survival rate of 90%. The PEG tube retention rate was 7%. Complications included 2 readmissions with dehydration, 1 aspiration pneumonia, and 2 with minor oropharyngeal bleeding. Ninety-one percent of patients resumed an oral diet by the first postoperative visit. CONCLUSION: The initiation of a TORS program in the post-FDA setting can be achieved in a safe and efficient manner. Early results of pioneering TORS centers are reproducible. Continued investigation of TORS as a treatment option for oropharyngeal carcinoma is warranted

Endoscopic repair of high-flow cranial base defects using a bilayer button.

OBJECTIVES/HYPOTHESIS: Repair of the skull base still begins with a direct repair of the dural defect. We present a new button closure for primary repair of the dura for high flow defects. STUDY DESIGN: Retrospective review. METHODS: We reviewed our 20 cases of primary button grafts and compared the results to the previous 20 high-flow open-cistern cerebrospinal fluid (CSF) cases. Subjects were excluded if they had no violation of the arachnoid space or potential for low-flow CSF leak. The button is constructed so that the inlay portion is at least 25% larger than the dural defect, and the onlay portion is just large enough to cover the dural defect. The two grafts are sutured together using two 4-0 Neurolon sutures and placed with the inlay portion intradurally and the onlay portion extradurally. RESULTS: The button graft repair of open-cisternal defects had a drop in CSF leak complications to 10% (2/20), and these two leaks were repaired with the button technique as the salvage surgery. This is a significant improvement over the 45% leak rate in the prebutton graft group (P \u3c .03). In our button graft group we used nasoseptal flaps on 16/20 repairs, and 1/2 repairs that leaked in the button group did not have a nasoseptal flap. Lumbar drains were used in approximately 38% in both groups (P = .83). CONCLUSIONS: The button graft can be used in conjunction with the nasal septal flap or as a stand-alone repair with good results reducing the postoperative leak rate to 10% for high-flow CSF repairs

Detection of evolving injury to the brachial plexus during transaxillary robotic thyroidectomy.

OBJECTIVES/HYPOTHESIS: Continuous intraoperative neuromonitoring (IONM) of transcranial electric motor evoked potentials (tceMEPs) and somatosensory evoked potentials (SSEPs) has gained universal acceptance as an efficacious method for detecting emerging positional brachial plexopathy or peripheral nerve compression during spinal and shoulder surgery. This has implications for transaxillary thyroid surgery. STUDY DESIGN: Case report with literature review. METHODS: The patient underwent robotic transaxillary thyroid surgery with continuous tceMEP and SSEP monitoring of brachial plexus function. We present detailed IONM data depicting the emergence of positional brachial plexopathy. RESULTS: Significant amplitude loss of both IONM modalities were identified during an evolving positional plexopathy, which resolved upon upper extremity repositioning and conversion to an open procedure. No permanent nerve injury or deficit was noted following surgery. CONCLUSIONS: Given the potential for brachial plexus injury during robotic transaxillary thyroid surgery secondary to arm positioning, we recommend that continuous tceMEP and SSEP monitoring be considered during such procedures

Novel Irradiated Axial Rotational Flap Model in the Rodent

Abstract Objectives: To design an easily reproducible rodent rotational skin flap and to evaluate the effects of radiation on flap viability. Methods: Ten rats received 40 Gy irradiation to the abdominal wall. Following a recovery period of one month, a 3 X 8 cm fasciocutaneous flap based axially on the inferior epigastric vessel, was raised and rotated 60 degrees into a contralateral deficit. Five non-irradiated rats underwent the identical procedure as a control. Animals were sacrificed seven days postoperatively, areas of flap necrosis were documented, and histological specimens were taken to compare flap viability and vessel density. Results: 60% of the rats in the irradiated group had necrosis of the distal flap ranging from 1 to 6 cm from the distal edge, whereas none of the animals (0%) in the control group exhibited necrosis (p\u3c0.001). Histology revealed collagen and vascular changes in the irradiated skin. Vascular density analysis revealed a significant difference between radiated and non-radiated flaps; p = 0.004, 0.029 and 0.014 in the distal, middle and proximal segments of the flap respectively. Conclusion: This novel rat axial rotational flap model demonstrates increases flap necrosis and a decrease in vascular density due to the effects of radiation. Using a linear electron accelerator a dose of 40 gy can be delivered to the skin without resulting in devastating gastrointestinal side effects

Single institution implementation of permanent 131Cs interstitial brachytherapy for previously irradiated patients with resectable recurrent head and neck carcinoma

Purpose: Permanent interstitial brachytherapy is an appealing treatment modality for patients with locoregional recurrent, resectable head and neck carcinoma (HNC), having previously received radiation. Cesium-131 (131Cs) is a permanent implant brachytherapy isotope, with a low average photon energy of 30 keV and a short half-life of 9.7 days. Exposure to medical staff and family members is low; patient isolation and patient room shielding are not required. This work presents a single institution’s implementation process of utilizing an intraoperative, permanent 131Cs implant for patients with completely resected recurrent HNC. Materials & Methods: Fifteen patients receiving 131Cs permanent seed brachytherapy were included in this analysis. The process of pre-planning, selecting the dose prescription, seed ordering, intraoperative procedures, post-implant planning, and radiation safety protocols are described. Results: Tumor volumes were contoured on the available preoperative PET/CT scans and a pre-implant treatment plan was created using uniform source strength and uniform 1 cm seed spacing. Implants were performed intraoperatively, following tumor resection. In five of the fifteen cases, intraoperative findings necessitated a change from the planned number of seeds and recalculation of the pre-implant plan. The average prescription dose was 56.1 ±6.6 Gy (range, 40-60 Gy). The average seed strength used was 2.2 ±0.2 U (3.5 ±0.3 mCi). Patients returned to a recovery room on a standard surgical floor and remained inpatients, without radiation safety restrictions, based on standard surgical recovery protocols. A post-implant treatment plan was generated based on immediate post-operative CT imaging to verify the seed distribution and confirm delivery of the prescription dose. Patients were provided educational information regarding radiation safety recommendations. Conclusions: Cesium-131 interstitial brachytherapy is feasible and does not pose major radiation safety concerns; it should be considered as a treatment option for previously irradiated patients with recurrent, resectable HNC

Virtual Surgical Planning in Subscapular System Free Flap Reconstruction of Midface Defects.

OBJECTIVES: Reconstruction of the midface has many inherent challenges, including orbital support, skull base reconstruction, optimizing midface projection, separation of the nasal cavity and dental rehabilitation. Subscapular system free flaps (SF) have sufficient bone stock to support complex reconstruction and the option of separate soft tissue components. This study analyzes the effect of virtual surgical planning (VSP) in SF for midface on subsite reconstruction, bone segment contact and anatomic position. MATERIALS AND METHODS: Retrospective cohort of patients with midface defects that underwent SF reconstruction at a single tertiary care institution. RESULTS: Nine cases with VSP were compared to fourteen cases without VSP. VSP was associated with a higher number of successfully reconstructed subunits (5.9 vs 4.2, 95% CI of mean difference 0.31-3.04, p = 0.018), a higher number of successful bony contact between segments (2.2 vs 1.4, 95% CI of mean difference 0.0-1.6, p = 0.050), and a higher percent of segments in anatomic position (100% vs 71%, 95% CI of mean difference 2-55%, p = 0.035). When postoperative bone position after VSP reconstruction was compared to preoperative scans, the difference in anteroposterior, vertical and lateral projection compared to the preoperative \u27ideal\u27 bone position was82% of measurements. There were no flap losses. CONCLUSION: VSP may augment SF reconstruction of the midface by allowing for improved subunit reconstruction, bony segment contact and anatomically correct bone segment positioning. VSP can be a useful adjunct for complex midface reconstruction and the benefits should be weighed against cost

A systematic review of treating recurrent head and neck cancer: a reintroduction of brachytherapy with or without surgery.

Purpose: To review brachytherapy use in recurrent head and neck carcinoma (RHNC) with focus on its efficacy and complication rates. Material and methods: A literature search of PubMed, Ovid, Google Scholar, and Scopus was conducted from 1990 to 2017. Publications describing treatment of RHNC with brachytherapy with or without surgery were included. The focus of this review is on oncologic outcomes and the safety of brachytherapy in the recurrent setting. Results: Thirty studies involving RHNC treatment with brachytherapy were reviewed. Brachytherapy as adjunctive treatment to surgical resection appears to be associated with an improved local regional control and overall survival, when compared with the published rates for re-irradiation utilizing external beam radiotherapy (RT) or brachytherapy alone. Safety data remains variable with different isotopes and dose rates with implantable brachytherapy demonstrating a tolerable side effect profile. Conclusions: Although surgery remains a mainstay treatment for RHNC, intraoperative interstitial brachytherapy delivery as adjunctive therapy may improve the treatment outcome and may be associated with fewer complication rates as compared to reirradiation using external beam radiotherapy. Further investigations are required to elucidate the role of brachytherapy for RHNC

Mutation signature analysis identifies increased mutation caused by tobacco smoke associated DNA adducts in larynx squamous cell carcinoma compared with oral cavity and oropharynx.

Squamous cell carcinomas of the head and neck (HNSCC) arise from mucosal keratinocytes of the upper aero-digestive tract. Despite a common cell of origin and similar driver-gene mutations which divert cell fate from differentiation to proliferation, HNSCC are considered a heterogeneous group of tumors categorized by site of origin within the aero-digestive mucosa, and the presence or absence of HPV infection. Tobacco use is a major driver of carcinogenesis in HNSCC and is a poor prognosticator that has previously been associated with poor immune cell infiltration and higher mutation numbers. Here, we study patterns of mutations in HNSCC that are derived from the specific nucleotide changes and their surrounding nucleotide context (also known as mutation signatures). We identify that mutations linked to DNA adducts associated with tobacco smoke exposure are predominantly found in the larynx. Presence of this class of mutation, termed COSMIC signature 4, is responsible for the increased burden of mutation in this anatomical sub-site. In addition, we show that another mutation pattern, COSMIC signature 5, is positively associated with age in HNSCC from non-smokers and that larynx SCC from non-smokers have a greater number of signature 5 mutations compared with other HNSCC sub-sites. Immunohistochemistry demonstrates a significantly lower Ki-67 proliferation index in size matched larynx SCC compared with oral cavity SCC and oropharynx SCC. Collectively, these observations support a model where larynx SCC are characterized by slower growth and increased susceptibility to mutations from tobacco carcinogen DNA adducts