Average Treatment Times Research Articles

Knowledge-based planning for Gamma Knife.

Current methods for Gamma Knife (GK) treatment planning utilizes either manual forward planning, where planners manually place shots in a tumor to achieve a desired dose distribution, or inverse planning, whereby the dose delivered to a tumor is optimized for multiple objectives based on established metrics. For other treatment modalities like IMRT and VMAT, there has been a recent push to develop knowledge-based planning (KBP) pipelines to address the limitations presented by forward and inverse planning. However, no complete KBP pipeline has been created forGK. To develop a novel (KBP) pipeline, using inverse optimization (IO) with 3D dose predictions for GK. Data were obtained for 349 patients from Sunnybrook Health Sciences Centre. A 3D dose prediction model was trained using 322 patients, based on a previously published deep learning methodology, and dose predictions were generated for the remaining 27 out-of-sample patients. A generalized IO model was developed to learn objective function weights from dose predictions. These weights were then used in an inverse planning model to generate deliverable treatment plans. A dose mimicking (DM) model was also implemented for comparison. The quality of the resulting plans was compared to their clinical counterparts using standard GK quality metrics. The performance of the models was also characterized with respect to the dosepredictions. Across all quality metrics, plans generated using the IO pipeline performed at least as well as or better than the respective clinical plans. The average conformity and gradient indices of IO plans was 0.737 0.158 and 3.356 1.030 respectively, compared to 0.713 0.124 and 3.452 1.123 for the clinical plans. IO plans also performed better than DM plans for five of the six quality metrics. Plans generated using IO also have average treatment times comparable to that of clinical plans. With regards to the dose predictions, predictions with higher conformity tend to result in higher quality KBP plans. Plans resulting from an IO KBP pipeline are, on average, of equal or superior quality compared to those obtained through manual planning. The results demonstrate the potential for the use of KBP to generate GK treatment with minimal humanintervention.

International collaboration between low-middle-income and high-income institutions to improve radiation therapy care delivery.

The Philippines is a lower-middle-income island country with over 153 000 new cancer diagnosis each year. Despite many patients needing radiotherapy as part of disease management, there remains limitations to access. Currently, the Philippines has 50 linear accelerator facilities serving a population of 110 million. However, given the recommendation of 1 linear accelerator for every 250 thousand people, it is evident that the demand for accessible radiotherapy resources is significantly underserved in the country. This paper outlines the collaboration between GenesisCare Solutions (GCS) and Fairview Cancer Center (FCC) to address efficiency and access within the radiotherapy department at FCC. Through international collaboration between GCS and FCC, areas for improvement were identified and categorized into four domains: Dosimetry quality, Patient workflow, Data & Reporting, and Information Technology (IT) Infrastructure. Action plans were developed then implemented. A baseline measurement was obtained for each domain, and post-implementation evaluation undertaken at 3 months, 6 months, and 12 months. Data captured within the electronic medical record system was extrapolated, and average treatment times were established for pre- and post-engagement. A paired, 2-tailed t-test was used for statistical analysis of outcome parameters using IBM SPSS version 23 for all statistics. Twelve months post-initial engagement, all four domains saw positive outcomes. Improved plan quality linked to Intensity Modulated Radiotherapy (IMRT) utilization rates saw an increase from 20% to 54%. A significant reduction in patient average wait times was also observed, from 27 to 17 min (p≤0.001). Prior to engagement, tracking patient demographics and diagnosis was not prioritized, post engagement an average of 92% diagnosis entry compliance was achieved. Through the collaboration of GCS and FCC, objectives in all action plan domains were achieved, highlighting the benefits of collaboration between low-middle-income and high-income institutions.

Dose-Painting Linear Accelerator Radiosurgery of Glomus Jugulare With Dosimetric Comparison to Gamma Knife.

Objectives In this study, we outline our rationale for delivering a dose of ≥15 Gy in stereotactic radiosurgery (SRS) of glomus jugulare tumor (GJT) while ensuring the avoidance of complications associated with doses >13 Gy to the facial nerve. To avoid such complications, we initially utilized the Gamma Knife Perfexion (GK) system (Elekta Instrument AB, Stockholm, Sweden) at our institution but encountered challenges related to lengthy treatment times and difficulty in sculpting doses to minimize doses to spare the facial nerve. As a potential solution, we propose the use of HyperArc (Varian Medical Systems, Palo Alto, CA), a newly developed automated delivery platform for linear accelerator (LINAC)-based SRS. HyperArc offers the potential for faster treatment and more complex shaping of the radiotherapy dose with multiple arcs and multi-leaf collimators. Methods We retrospectively reviewed nine cases of patients with GJT treated with HyperArc. Patients' demographic and treatment data were collected. Additionally, simulated GK treatment plans were created and compared with HyperArc plans to assess time savings, PTV coverage, and plan quality. Results One male and eight female patients, with a mean age of 63.9 years, were included. Treatments were delivered on average in 29 minutes, achieving 95-100% of the tumor while limiting the facial nerve to <13 Gy. Treatments replanned using our GK system could achieve only 92-99% tumor coverage while respecting facial nerve constraints, with average treatment times of 180 minutes. Comparable plan quality parameters were attained with both modalities. Conclusions The HyperArc system provides a qualitatively satisfactory and rapid treatment delivery of a highly sculpted radiotherapy dose to maximize tumor coverage and minimize facial nerve complications.

Comparison of the Direct Power Consumption for Different Linac Treatment Parameters in External Beam Radiation Therapy

The negative impact of climate change on the environment has led to increasing concern around the world. Relatively little is known about the contribution of radiation oncology systems to carbon emissions. This study measures the energy utilization of Linac-based EBRT for different treatment parameters and techniques, which was then converted to power use (kWh) and ultimately a carbon footprint of various photon treatment approaches. A Varian TrueBeam was evaluated. The direct power consumption was measured using a Fluke 1736 Power Logger, recorded in one-second intervals for one week. Different photon and electron beam energies, dose rates, treatment techniques (3D, IMRT, gated), and imaging types (kV, MV) were evaluated. Clinical treatment plans were reviewed, and average treatment times used to determine kWh. IRB approval was obtained. The Greenhouse Gas Equivalencies Calculator was used to determine kg of CO2. Power draw for 6 MV, 10 MV, and 18 MV at a rep rate of 600 MU/min was 31.6, 32.0, and 27.5 kW, respectively. The power draw for end of range dose rates for 6 MV (60, 600), 6 FFF (400, 1400), 10 FFF (400, 2400), and 6 MeV (100, 1000) were (22.2, 31.6 kW), (23.7, 31.6 kW), (19.6, 32.1 kW), and (22.6, 23.6 kW), respectively. 6 MV open 2D fields, modulated IMRT fields, and gated/beam hold fields had similar power draw at 31.6, 31.7, and 31.9 kW, respectively. Portal MV imaging with 2.5 MV beam was 32.5 kW, while CBCT and kV/kV imaging was ∼11 kW and not distinguishable from baseline power fluctuations. A total of 191 delivered treatment plans were reviewed. Electron plans (n = 8) treatment time was on average 29 sec (16 sec STDEV) per fraction and 635 sec (185 sec STDEV) per course, 2D/3D plans (n = 63) were 77 sec (32 sec STDEV) and 1004 sec (1002 sec STDEV), and IMRT plans (n = 120) were 182 sec (60 sec STDEV) and 5351 sec (2401 sec STDEV), respectively. The kWh per treatment for electron, 2D/3D, and IMRT plans were 0.19, 0.68, and 1.6 kWh, respectively. The CO2 equivalent for electrons, 2D/3D, and IMRT techniques are 0.08, 0.29, and 0.7 kg. There was some variability in the power draw for different energies and different dose rates but was relatively stable around 32 kW. Power consumption for clinical therapy is a result of kW power draw multiplied by duration of beam delivery, which for our patients varied significantly as a function of technique and number of fractions delivered. Reduction in radiation oncology carbon footprint will likely be driven more by number of fractions and type of treatment technique, and length of patient commute, rather than beam energy and dose rate selection.

An observational study evaluating the impact on prostate patient outcomes and experiences when radiation therapists use a standard grading system tool to assess and document treatment-related toxicities and interventions

Background/PurposeMen undergoing radiation therapy (RT) treatment for prostate cancer (PC) often experience acute urinary, bowel, sexual, and hormonal toxicities. Timely screening, management, and documentation of these toxicities is an integral part of clinician practice, ensuring patients receive the care they require. Various screening tools, completed by either the patient or the clinician, are available, which allow clinicians to collect and respond to these toxicity outcomes; however there is a paucity of literature regarding the effective use and timing of these tools during RT treatment. This study aims to evaluate the feasibility of conducting comprehensive toxicity screening and symptom management using a toxicity screening tool in one of the busiest RT departments in Canada. Specifically, the use of a toxicity screening tool and its effect on the quality of toxicity documentation, operational impact, and patient reported outcomes (PRO). Methods90 consented patients were allocated to either the structured or non-structured arm. Patients in the structured arm were assessed weekly by radiation therapists for 13 toxicities across four domains (bladder, bowel, hormonal, and sexual), using an in-house developed structured questionnaire, known as the Grid, to complete the National Cancer Institute's Common Toxicity Criteria for Adverse Events v3 (CTCAEv3). Patients in the non-structured arm were assessed and had free text clinical documentation charted according to current department policy. The Expanded Prostate Cancer Index Composite (EPIC), a PRO tool to evaluate patient function and bother after prostate cancer treatment, was completed by all study patients on a weekly basis. Statistical analysis compared documentation completeness, EPIC scores, patient satisfaction, and operational impact between study arms, as well as evaluated optimal timing of toxicity assessments. ResultsAssessment of the non-structured arm for completeness revealed an inconsistent and insufficient amount of documentation for the bladder and bowel domains. As for both the sexual and hormonal domains, documentation was largely absent. There was no difference in EPIC scores and patient satisfaction scores between the structured arm and the non-structured arm. Evaluation of the timing of PROs showed significant week to week change for the bladder and bowel toxicities, but not the sexual and hormonal toxicities. Finally, the use of the Grid revealed no significant impact on daily operations, only increasing average treatment times by seven seconds, and did not create any additional workload for the oncologists. ConclusionsUse of the Grid increased documentation completeness without negatively impacting clinical flow or operations, despite the fact that PROs were not improved. Based on EPIC PRO scores, bladder and bowel toxicities should be evaluated on a weekly basis during RT treatment, while sexual and hormonal toxicities need only be evaluated monthly.

Early experience with MR-guided adaptive radiotherapy using a 1.5 T MR-Linac: First 6 months of operation using adapt to shape workflow.

The magnetic resonance linear accelerator (MRL) offers improved soft tissue visualization to guide daily adaptive radiotherapy treatment. This manuscript aims to report initial experience using a 1.5 T MRL in the first 6 months of operation, including training, workflows, timings and dosimetric accuracy. All staff received training in MRI safety and MRL workflows. Initial sites chosen for treatment were stereotactic and hypofractionated prostate, thoraco-abdomino-pelvic metastasis, prostate bed and bladder. The Adapt To Shape (ATS) workflow was chosen to be the focus of treatment as it is the most robust solution for daily adaptive radiotherapy. A workflow was created addressing patient suitability, simulation, planning, treatment and peer review. Treatment times were recorded breaking down into the various stages of treatment. A total of 37 patients were treated and 317 fractions delivered (of which 313 were delivered using an ATS workflow) in our initial 6 months. Average treatment times over the entire period were 50 and 38 min for stereotactic and non-stereotactic treatments respectively. Average treatment times reduced each month. The average difference between reference planned and ionization chamber measured dose was 0.0 ± 1.4%. The MRL was successfully established in an Australian setting. A focus on training and creating a detailed workflow from patient selection, review and treatment are paramount to establishing new treatment programmes.

Minimum Bladder Reference Contour To Guide Patient Setup For Prostate Radiotherapy

To evaluate if a model—based approach for bladder matching at the time of treatment reduces imaging and treatment time for prostate SBRT patients treated with a full bladder protocol. Prospectively collected data from prostate SBRT patients consecutively treated between 9/2019 and 1/2020 was used to select patients who experienced at least one treatment delay due to perceived underfilling of their bladder on CBCT. At our institution, a full bladder protocol (1 cup of water 45 min prior) checked by CBCT is employed for all treatments. When the pre-treatment bladder volume is smaller than the simulated volume, patients are asked to either wait longer and/or drink more water. A minimum bladder reference contour [min_bladder] was calculated for each patient by deforming the bladder contour at simulation [sim_bladder] with decreasing margins (1, 1.5, 2, 2.5, 3, 3.5, 4.5, and 5 cm) and identifying the smallest contour that met the bladder planning constraints (Maximum < 105%, V20Gy < 50% and V 36Gy < 10%). To evaluate the accuracy and efficacy of a model-based approach where min_bladder was used as the threshold for treatment initiation, the bladder on initial rejected CBCT was contoured, dose calculated and compared to min_bladder dose. Furthermore, treatment setup time reductions were estimated retrospectively as if the model had been used in the clinic. 64 patients were included in this study, of which 23 (36%) had delays due to perceived bladder underfilling (35/115 fractions). The average ± standard deviation sim_bladder and min_bladder size were 321 ± 117 and 134 ± 53 cm3, respectively. Comparing the min_bladder to the actual rejected setup bladder volume [rej_bladder] on CBCT predicted that the bladder would have been large enough for 22 fractions (63%) while for 13 fractions (37%) additional filling would have been necessary. When reviewing the doses to the rej_bladder, we found a model accuracy of 82%. For 3 fractions, the model predicted the volume was too small, but the rej_bladder met the dose constraints. For one patient, the rej_bladder shape did not conform well to the model and even though the rej_bladder was larger than the min_bladder, it did not meet the bladder constraints. The average total treatment times as recorded in Aria for fractions without delays versus those with delays was 28.1 ± 18 vs 49.6 ± 15 min (p<0.0001) (Student's t-test). Average estimated time that could be saved using the minimum bladder reference was 25± 11 min per fraction and number of CBCTs reduced from 2 to 1 per fraction. We found 36% of our prostate SBRT patients were delayed at least once during their treatment due to underfilling of their bladder. We demonstrate that employing a patient-specific model-based approach using a minimum bladder reference created at the time of planning could prevent treatment delays in the majority of cases and reduce the number of CBCTs used to setup patients for prostate SBRT.

37 Impact of Census-Based Reassignment of Nursing Staff to Reduce Emergency Department Patient Wait Times, Lengths of Stay, and Boarding Times

The Centers for Medicare & Medicaid Services (CMS) have traditionally utilized the emergency department (ED) metrics to gauge operational performance. CMS has identified timeliness and efficiency as core attributions for the ED, specifically length of stay (LOS) and boarding time. Prolonged times reduce the quality of care and can lead to increased inpatient length of stay and poor clinical outcomes. Furthermore, lengthy LOS has been associated with decreased patient satisfaction. Prior literature reports that higher staffing levels may result in earlier discharges and improved metrics. However, financial barriers may prevent hospitals from hiring more staff. Given the current allocation of staffing, we hypothesize that our novel queueing algorithm can reduce metrics times without increasing staffing. The intervention was based on a novel fluid queueing model, which quantifies the impact of the assignment of available ED and ED Inpatient (EDIN) nursing staff to the different areas of an urban quaternary ED at the beginning of each shift. The algorithm accounts for two stages of care (in-treatment and boarding) and two types of nursing providers, ED and EDIN nurses, and is based on the current number of patients at each ED area at the beginning of the shift, boarding times, fraction of admitted patients, average treatment times, and the time-dependent arrival rates with the goal to minimize nurse idleness. The study involved two 2-week periods; the period before the intervention (Off Period), March 5, 2018, to March 18, 2018, and the period after the intervention (On Period), March 19, 2018, to April 3, 2018. The data contains operational level information (times stamps for arrival, first treatment, discharge, change to admit status as well as assigned area and disposition) and patient-level demographic and medical information (age, sex, race and ethnicity, insurance type, ESI level, and Elixhauser score). We measured the impact of the intervention on patient waiting times, evaluation to disposition decision, evaluation to discharge, and boarding times for admitted patients. Our data consists of 2383 Off Period and 2617 On Period patient visits, stratified by ED disposition. In both groups, “evaluation to discharge”, “disposition decision to admission,” and “ED arrival to discharge from ED”, the On Period was associated with statistically significant reductions in these time metrics. On the other hand, “ED arrival to evaluation” and “evaluation to disposition” demonstrated no statistical difference. Our novel fluid queueing model demonstrated improvements in ED metrics without showing a clinically significant increase in “ED arrival to evaluation time.” The algorithm had successfully shown that operationally based metrics can improve without increasing nurse staffing.TableAdmitted PatientsDischarged PatientsOff Period (n = 720)On Period (n = 765)p-valueOff Period (n = 1586)On Period (n = 1755)p-valueCharacteristicsAge63.907 (18.818)64.442 (18.507)0.58149.070 (18.614)50.901 (19.334)0.005ESI3.00 [2.00-3.00]3.00 [2.00-3.00]0.5083.00 [3.00-4.00]3.00 [3.00-4.00]0.015Elixhauser4.00 [2.00-7.00]4.00 [2.00-7.00]0.5741.00 [0.00-2.00]1.00 [0.00-3.00]0.005Sex (M)364 (50.6%)377 (49.3%)0.623676 (42.6%)741 (42.2%)0.815Race0.5870.438White384 (53.3%)409 (53.5%)712 (44.9%)781 (44.5%)Black110 (15.3%)125 (16.3%)261 (16.5%)323 (18.4%)Asian37 (5.1%)37 (4.8%)71 (4.5%)88 (5.0%)Pacific Islander8 (1.1%)4 (0.5%)20 (1.3%)22 (1.3%)Other99 (13.8%)117 (15.3%)272 (17.2%)301 (17.2%)Unknown82 (11.4%)73 (9.5%)250 (15.8%)240 (13.7%)Ethnicity0.3970.249Hispanic/Latino90 (12.5%)88 (11.5%)229 (14.4%)267 (15.2%)Not Hispanic/Latino353 (49.0%)402 (52.5%)631 (39.8%)735 (41.9%)Unknown277(38.5%)275 (35.9%)726 (45.8%)753 (42.9%)Insurance0.1460.005Private146 (20.3%)134 (17.5%)767 (48.4%)767 (43.7%)Medicaid119 (16.5%)105 (13.7%)395 (24.9%)433 (24.7%)Medicare365 (50.7%)406 (53.1%)320 (20.2%)441 (25.1%)Self-Pay9 (1.2%)15 (2.0%)104 (6.6%)114 (6.5%)Unknown81 (11.2%)105 (13.7%)0 (0.0%)0 (0.0%)Operational MetricsWaiting Time (min)ED arrival to Eval17.162 (21.140)19.086 (26.865)0.12715.719 (20.885)16.888 (24.572)0.141Treatment Time (hrs)Eval to Disposition5.064 (3.328)5.214 (3.819)0.423Eval to Discharge21.700 (16.494)19.158 (13.092)<0.0016.360 (15.023)5.282 (3.449)0.004Boarding Time (hrs)Dispo to Admit16.717 (15.712)14.069 (12.283)<0.001Total LOS (hrs)ED Arrival to DC22.010 (16.539)19.468 (13.147)0.0016.619 (15.007)5.552 (3.486)0.004Mean (standard deviation) or median [interquartile range] of the outcome measures during the OFF and ON periods. Open table in a new tab

Daily Time of Radiation Treatment Is Associated with Subsequent Oral Mucositis Severity during Radiotherapy in Head and Neck Cancer Patients.

Limited treatment options are available for oral mucositis, a common, debilitating complication of cancer therapy. We examined the association between daily delivery time of radiotherapy and the severity of oral mucositis in patients with head and neck cancer. We used electronic medical records of 190 patients with head and neck squamous cell carcinoma who completed radiotherapy, with or without concurrent chemotherapy, at Roswell Park Comprehensive Cancer Center (Buffalo, NY) between 2015 and 2017. Throughout a 7-week treatment course, patient mouth and throat soreness (MTS) was self-reported weekly using a validated oral mucositis questionnaire, with responses 0 (no) to 4 (extreme). Average treatment times from day 1 until the day before each mucositis survey were categorized into seven groups. Multivariable-adjusted marginal average scores (LSmeans) were estimated for the repeated- and maximum-MTS, using a linear-mixed model and generalized-linear model, respectively. Radiation treatment time was significantly associated with oral mucositis severity using both repeated-MTS (n = 1,156; P = 0.02) and maximum-MTS (n = 190; P = 0.04), with consistent patterns. The severity was lowest for patients treated during 8:30 to <9:30 am (LSmeans for maximum-MTS = 2.24; SE = 0.15), increased at later treatment times and peaked at early afternoon (11:30 am to <3:00 pm, LSmeans = 2.66-2.71; SEs = 0.16/0.17), and then decreased substantially after 3 pm. We report a significant association between radiation treatment time and oral mucositis severity in patients with head and neck cancer. Although additional studies are needed, these data suggest a potential simple treatment time solution to limit severity of oral mucositis during radiotherapy without increasing cost.

DSA-guided percutaneous sclerotherapy for children with oropharyngeal low-flow venous malformation.

The present study investigated the efficacy and safety of digital subtraction angiography-guided 3% polidocanol foam sclerosing agent, as well as the combination of pingyangmycin and dexamethasone, for the treatment of children with oropharyngeal low-flow venous malformation. A total of 27 children with 35 lesions with oropharyngeal low-flow venous malformation were included. The subjects were randomly divided into Groups A (13 patients with 16 lesions, treated with 3% polidocanol foam sclerosing agent) and B (14 patients with 19 lesions, treated with pingyangmycin + dexamethasone), respectively. The clinical efficacies and adverse reactions were analyzed and compared between these two groups. The average number of treatment times for Group A was 2.45±0.6, with an efficacy rate of 87.50%, while the average number of treatment times for Group B was 2.07±0.4, with an efficacy rate of 84.21%. No significant difference was found in the average treatment times or efficacy rates between Groups A and B. In addition, the adverse reaction incidence for Groups A and B were 38.46 and 14.29%, respectively, with statistically significant differences between these two groups. The combination of pingyangmycin and dexamethasone was safe and effective in treating children with oropharyngeal low-flow venous malformation, with fewer adverse reactions and is worthy of clinical promotion.

Implementing butterfly volumetric modulated arc radiotherapy (VMAT) with deep inspiration breath hold (DIBH) for mediastinal lymphomas

Keywords: Lymphoma, Voluntary DIBH, VMAT radiotherapy, butterfly technique Introduction: Radiotherapy for mediastinal lymphomas is associated with significant long term side effects particularly to the heart, lungs and breasts1&2. Studies have shown that the butterfly technique can reduce dose to these organs3. This technique was implemented in combination with voluntary DIBH to manage target volume motion and reduce dose to the heart. Voluntary DIBH allowed the target volume to contract left/right and elongate anterior/posterior so that the main mediastinal volume was positioned away from the lungs and heart. Voluntary DIBH does not involve costly equipment and is well tolerated by patients. The technique was adapted from the breast protocol previously implemented in the department. Method and Materials: Patients were scanned in a modified 7 point thermoplastic shell, made with the patient in voluntary DIBH (patient breathing after every 20seconds before going back into breath-hold). Measurements from the alignment tattoos to in room lasers during voluntary DIBH at CT were recorded and DIBH stability maintained during treatment by visual alignment of lasers to reference marks drawn on using the recorded measurements. Organs at risk and clinical volumes were outlined. Field placement was considered carefully as the angles were limited due to the large head of the Varian LINACS. Routinely superior/inferior, anterior, and posterior arcs were used. Depending on the size and position of target volume another lateral beam may utilised. Planned using Pinnacle SmartArc with arcs split to keep within a 20second limit. Results: Implementation: A Day 0 was introduced for a dummy run. Patients practiced holding their breath for 20seconds, however the CBCT/arcs took longer. CBCT/treatment was interrupted to allow the patient to breathe normally before commencing breath hold again. Pitch caused set-up issues in 7 cases. Most patients were able to comply with consistent breath hold. CT, planning and Treatment times are longer which can have an impact on a busy department. Conclusion and Discussion: A total of 13 patients have been treated with this technique. Further work is being undertaken to investigate the average treatment times, DVHs and imaging. Numerical

Examining Radiation Treatment Appointment Times at a Canadian Cancer Centre: A Timing Study

IntroductionTechnological advancements in radiation therapy have led to more complex treatment techniques such as volumetric modulated arc therapy, and in turn, more daily image verification. As treatment complexity increases, it is important to consider what effect this may have on treatment time. Additional factors that may influence treatment times are patient-centered care and mobility status. The aim of this study is to determine optimal radiation treatment appointment times based on site, technique, imaging requirements, and patient needs. MethodsData from 535 fractions of radiation treatments were collected and analyzed between June 2016 and July 2017 by a team of eight radiation therapists at BC Cancer Vancouver Centre. Data collectors documented a number of data points, including treatment unit, scheduled appointment time, scheduled appointment duration (booked in 12 minute increments), treatment site, treatment technique, imaging modality, pre-treatment-related and post-treatment-related activity time, patient mobility status, etc. Student's t-test was performed for each site/technique to determine if the mean total treatment time was significantly different from the standard appointment time for that site. A two-sample unpaired t-test assuming unequal variance was used to compare average treatment times of the same site with different imaging modalities. Student's t-test was also used to compare average treatment times for ambulatory patients versus patients requiring some form of mobility assistance. ResultsAverage treatment times for 6 of the 10 sites used for data analysis were longer than standard booked times and showed statistical significance (prostate/prostate bed: n = 82, P < .001; chest: n = 32, P < .001, palliative 1 treatment site: n = 28, P < .05, gyne pelvis only treatment: n = 25, P < .001, head & neck: n = 56, P < .001, and rectum: n = 28, P < 0.05). The breast/chest wall + nodes site had a significantly shorter treatment time than the standard booked appointment time (n = 87, P < .001). Analysis of the prostate/prostate bed imaging showed a significant difference between daily cone beam computed tomography and daily kilovoltage treatment time, with cone beam computed tomography imaging taking 3.83 ± 1.36 (P < .001) minutes longer on average than kilovoltage imaging. Average treatment time for patients requiring mobility assistance was 20% longer than for patients requiring no assistance (P = .02). ConclusionThe majority of the most common sites and techniques treated at our centre were inappropriately booked. Radiation therapy appointment durations are influenced by several factors, including site, technique complexity, imaging, and patient care. It is recommended that radiation treatment centres evaluate appointment times regularly as technology, treatment delivery, and professional practice standards evolve to ensure high-quality patient care.

Use of volumetric modulated arc radiotherapy in patients with early stage glottic cancer.

We compared conformal, intensity-modulated radiotherapy (IMRT) and intensity-modulated arc therapy (IMAT) in early stage glottic cancer in terms of dosimetric features as target coverage, dose to the organs at risk and total treatment time. Five consecutive T1 glottic squamous cell carcinoma patients were selected for the study. Three-dimensional conformal radiotherapy (3D-CRT), 3-field or 5-field intensity-modulated radiotherapy (3F-IMRT and 5F-IMRT), or IMAT, which was in 2 different forms--a regular IMAT (R-IMAT) and an alternative IMAT (A-IMAT) with an unirradiated section, was planned for each patient. The prescribed dose was 63 Gy in 28 fractions. The minimum dose for 95% of the clinical target volume (D95), maximum dose point at clinical target volume (Dmax), total monitor units, left and right carotid artery doses (V35 and V50 - percentage of volume receiving 35 Gy and 50 Gy), and total treatment time were calculated for each plan. Median D95 values in the 5 plans studied with each technique ranged between 63 and 63.3 Gy (P = NS). Median Dmax values for each technique ranged between 65.4 and 70.8 Gy. The number of hot spots with IMRT and IMAT was significantly higher than with 3D-CRT plans. Conformal radiotherapy plans median V35 (93.6%) and V50 (76.6-83.3%) values for carotid arteries were significantly higher than with IMRT and IMAT (2.9%-11.4% and 0.0%). Average treatment times for 3D-CRT, 3F-IMRT, 5F-IMRT, R-IMAT and A-IMAT techniques were calculated as 64, 119, 147, 39 and 32 seconds, respectively. IMAT has significantly decreased the treatment time compared to IMRT and 3D-CRT with acceptable homogeneous clinical target volume coverage and low carotid dose.

Cephalometric study of Class II Division 1 patients treated with an extended-duration, reinforced, banded Herbst appliance followed by fixed appliances.

The Herbst appliance has been used in the treatment of Class II malocclusions with deficient mandibles. Various protocols, including different durations of the orthopedic treatment phase and stepwise advancement of the mandible, have been advocated for increasing the orthopedic effects. The objective of this study was to investigate the skeletal and dental changes in patients treated with a reinforced banded Herbst appliance for an extended duration and fixed appliance therapy. The study group consisted of 30 patients (16 boys, 14 girls; mean age, 12.3±2.5years) with Class II Division 1 malocclusions who were successfully treated with the new Herbst protocol followed by fixed appliances. Lateral cephalometric radiographs were taken before treatment, at the completion of Herbst treatment, and after removal of fixed appliances. The average treatment times were 1.5±0.7years for the Herbst treatment and 1.8±0.5years for the fixed appliances. A control Class II sample from the Bolton-Brush study was used to subtract growth from treatment changes to determine the appliance effect. Data were analyzed using analysis of variance and the Tukey-Kramer test. After the Herbst treatment, the incisal relationships of all subjects had been overcorrected to end-to-end relationships. Overjet was reduced by 7.2mm after subtracting changes from growth. The skeletal contribution was 2.5mm (35%), and the dental contribution was 4.7mm (65%). The molar relationship was overcorrected to a more Class I relationship by 7.5mm. The Wits appraisal was improved by 4.2mm. Vertically, overbite was decreased by 3.3mm. The maxillary and mandibular molars were extruded by 1mm. The occlusal plane rotated clockwise by 5° with little change in the mandibular plane angle. After the treatment with fixed appliances, the overjet correction was maintained at 7.6mm. The skeletal contribution was 2.9mm (38%), and the dental contribution was 4.7mm (62%). The molar relationship was corrected to a Class I relationship by 5.9mm. The Wits appraisal was improved by 3.2mm. Vertically, overbite was decreased by 4.2mm. The maxillary and mandibular molars were extruded by 0.3 and 0.8mm, respectively. The occlusal plane rotated clockwise by 1.2° with little change in the mandibular plane angle. Doubling the usual orthopedic treatment time with the reinforced Herbst appliance followed by fixed appliance therapy was effective in correcting Class II Division 1 malocclusions with excess overjet and overbite. In this sample of successfully treated patients, most changes after Herbst and fixed appliance therapy were dentoalveolar (62%). However, the skeletal changes attained in the orthopedic phase of treatment were maintained after fixed appliance therapy.

Abstract TP385: Decreasing Door-to-Needle Times for Acute Ischemic Stroke Patients

Background and Purpose: The Joint Commission recommendation is to meet door-to-needle (DTN) times of less than 60 minutes in 50% of tPA recipients. Lake Cumberland Regional Hospital is a certified primary stroke center by The Joint Commission and has strived to develop a process that drives DTN times to less than 60 minutes for acute ischemic stroke patients being treated with tissue plasminogen activator (tPA). Baseline data from 2014 showed tPA compliance was 27% (n=15). In 2015, pre-implementation tPA compliance was 0% (n=3). Methods: Guided by a process map outlining time frames for all steps in the tPA administration process, findings were utilized to identify barriers, inefficiencies, and solutions. An educational program was developed and centered on identified barriers. Educational sessions were completed for all emergency department staff. DTN times were analyzed before and after implementation of educational program. A timekeeper role was implemented in the emergency department to increase awareness during cases of tPA administration. Results: 100% of Emergency Department staff was educated on process map, Joint Commission recommendations, and role of timekeeper. Since completion of educational sessions and implementation of timekeeper role, Lake Cumberland Regional Hospital has met The Joint Commission DTN recommendation in 78% (n=9) of patients treated with tPA. As of August 11 th , overall DTN compliance for 2015 at Lake Cumberland Regional Hospital was 54%. Conclusions: Average DTN treatment times were decreased and compliance with The Joint Commission standard of meeting DTN times of less than 60 minutes in 50% of tPA cases was improved. For continued identification of performance improvement initiatives, debriefings are conducted after each tPA case with all staff involved to discuss strengths, barriers, and opportunities for improvement.

SU‐E‐T‐768: Treatment Time Nomogram for Strut‐Based Accelerated Partial Breast Applicators

Purpose:The purpose of this work was to generate a tabular nomogram of treatment times for strut‐based APBI applicators. The nomogram is intended to provide guidance and a quality assurance check for clinics establishing new treatment techniques or transitioning from balloon‐based applicators.Methods:A retrospective analysis was conducted of 486 patients receiving APBI using strut‐based applicators at three separate institutions. Strut‐based applicators are composed of a central channel surrounded by 6 close‐range (“mini”), 6 mid‐range, 8, or 10 peripheral channels. Patient data was organized based on applicator size (a surrogate of treatment volume) and number of organs at risk. Three organs at risk categories were determined based on the proximity of the device to the patient's skin and/or chest wall (0, 1, or 2 OARs). The proximity criterion was defined as being &lt; 5 mm from the cavity wall/peripheral struts. A tabular nomogram of treatment time (based on nominal 10 Ci source strength) was generated from descriptive statistics of each combination of applicator size and organs at risk category.Results:The average treatment time was observed to be directly related to applicator size and, to a lesser extent, inversely related to the number of nearby organs at risk. Distributions of treatment times observed for each combination of applicator size and organs at risk category are depicted in Figure 1. The tabular nomogram featuring average treatment times with standard deviations is presented in Table 1.Conclusion:Strutbased APBI treatment times were observed to depend in a consistent manner on applicator size and number of nearby organs at risk. Information provided in the nomogram presented here represents several hundred treatments performed at multiple institutions. This data can serve as guidance or quality assurance for institutions with limited experience using strut‐based APBI applicators.

Personalized Radiation Therapy of Breast Cancers May Not Incur Substantial Increase in Treatment Delivery Time

A retrospective investigation was performed examining the treatment delivery time for breast cancer patients treated in our clinics. We hypothesized that the use of highly personalized radiation treatments of breast cancers might increase treatment delivery time substantially. We identified patients with breast cancers who completed non-IMRT tangential beam radiation therapy (RT) in the last three years. All patients received a whole breast radiation dose of 45-50 Gy at 1.8-2.0 Gy/fraction or 42.5 Gy at 2.66 Gy/fraction. Boost treatments to the tumor bed were excluded in this study. Personalizing treatment plans based on each individual’s normal tissue and tumor anatomy for optimal target coverage and critical organ sparing required using various numbers of radiation fields, beam energies, intensity modulation techniques and active breathing control (ABC). Resulting costs in delivering the plans were evaluated in terms of the time spent to complete each treatment fraction through the course. We measured the time spent on individual fractions by determining the total time from the moment the first treatment field was beamed on to the completion of last treatment field (averaged over all fractions). Treatment delivery records of 253 patients were analyzed, of whom 69% (N = 175) received radiation to whole breast (WB) only, 18% (N = 45) to WB plus axillary nodes (WB+Ax), 4% (N = 10) to WB plus internal mammary nodes (WB+IM), and 9% (N = 23) to WB plus axillary and IM nodes (WB+Ax+IM). Timing records for a total of 6,808 delivered fractions were analyzed to obtain the average treatment times. 27% (N = 69) of the studied patients were treated with ABC, of whom, those receiving RT to WB only had treatment times of 4.2±0.2, 4.7±0.3, 5.3±0.4, and 5.6±0.4 min respectively corresponding to 5 through 8 radiation fields treated, while those receiving RT to WB+Ax had a treatment time of 9.9±2.5 min. In the non-ABC group, patients receiving RT to WB only had treatment times of 2.9±0.3, 3.3±0.7, 3.7±0.4, 4.1±0.6, 4.5±0.9, 4.4±0.3, and 5.2±0.9 min respectively for 2 to 8 treatment fields used. Those receiving RT to WB+Ax, WB+IM or WB+Ax+IM had treatment times of 7.5±2.2, 7.4±2.8, and 13.2±3.1 min respectively. Among patients who were treated to WB only, the treatment times were 4.0±0.9 and 4.9±0.6 min for the non-ABC and ABC groups, respectively. For patients treated to WB+Ax, WB+IM or WB+Ax+IM, the average treatment times were respectively 8.3±2.3, 7.4±2.8, and 13.2±3.1 min. The average time required to deliver individual treatment fraction increases with the number of radiation fields used. The maximum increment is less than two and half minutes per fraction, which will not significantly impact overall clinical throughput. A time increment of similar magnitude is also observed in patients treated with ABC compared to those without ABC.

SU‐E‐J‐181: Magnetic Resonance Image‐Guided Radiation Therapy Workflow: Initial Clinical Experience

Purpose:The aims of this work are to describe the workflow and initial clinical experience treating patients with an MRI‐guided radiotherapy (MRIGRT) system.Methods:Patient treatments with a novel MR‐IGRT system started at our institution in mid‐January. The system consists of an on‐board 0.35‐T MRI, with IMRT‐capable delivery via doubly‐focused MLCs on three 6 0 Co heads. In addition to volumetric MR‐imaging, real‐time planar imaging is performed during treatment. So far, eleven patients started treatment (six finished), ranging from bladder to lung SBRT. While the system is capable of online adaptive radiotherapy and gating, a conventional workflow was used to start, consisting of volumetric imaging for patient setup using visible tumor, evaluation of tumor motion outside of PTV on cine images, and real‐time imaging. Workflow times were collected and evaluated to increase efficiency and evaluate feasibility of adding the adaptive and gating features while maintaining a reasonable patient throughput.Results:For the first month, physicians attended every fraction to provide guidance on identifying the tumor and an acceptable level of positioning and anatomical deviation. Average total treatment times (including setup) were reduced from 55 to 45 min after physician presence was no longer required and the therapists had learned to align patients based on soft‐tissue imaging. Presently, the source strengths were at half maximum (7.7K Ci each), therefore beam‐on times will be reduced after source replacement. Current patient load is 10 per day, with increase to 25 anticipated in the near future.Conclusion:On‐board, real‐time MRI‐guided RT has been incorporated into clinical use. Treatment times were kept to reasonable lengths while including volumetric imaging, previews of tumor movement, and physician evaluation. Workflow and timing is being continuously evaluated to increase efficiency. In near future, adaptive and gating capabilities of the system will be implemented.

비침습 레이저 조사기를 이용한 Osgood-Schlatter's disease의 치료 증례보고

Objectives: The purpose of this study was to assess the effect of Extravascular Laser System on Osgood-Schlatter Disease Methods: In this study, we treated the 6 cases of children who were diagnosed with Osgood-Schlatter disease with Extravascular Laser System. 4 of them were treated with acupuncture as well, the other 2 were given with combined acupuncture and Blood-pricking Treatment. For evaluation, 6 children explained the degree of pain relief by comparing with degree of pain before treatment. Results: Extravascular Laser System for Osgood-Schlatter Disease resulted in a significant decline in the subjective pain degree. All of them were almost cured. The average treatment times was 6.7 times, and the average treatment period was 26.7days. Conclusions We report the good result of the efficacy of extravascular laser system on Osgood-Schlatter Desease. Cases in this study, however, were small in number. Therefore more study is required.

Radiofrequency Coil for the Creation of Large Ablations: Ex Vivo and In Vivo Testing

PurposeVarious radiofrequency (RF) ablation electrode designs have been developed to increase ablation volume. Multiple heating cycles and electrode positions are often required, thereby increasing treatment time. The objective of this study was to evaluate the performance of a high-frequency monopolar induction coil designed to produce large thermal lesions (>3cm) with a single electrode insertion in a treatment time of less than 10minutes. Materials and MethodsA monopolar nitinol interstitial coil operated at 27.12MHz and 200W was evaluated. Ex vivo performance was tested in excised bovine liver (n=22). In vivo testing (n=10) was conducted in livers of seven Yorkshire pigs. Visual inspection, contrast-enhanced computed tomography (CT), and pathologic evaluation of ablation zones were performed. ResultsAverage ablation volumes in ex vivo and in vivo tests were 60.5cm3±14.1 (5.9×4.4×4.4cm) and 57.1cm3±13.8 (6.1×4.5×4.1cm), with average treatment times of 9.0minutes±3.0 and 8.4minutes±2.7, respectively. Contrast-enhanced CT ablation volume measurements corresponded with findings of gross inspection. Pathologic analysis showed morphologic and enzymatic changes suggestive of tissue death within the ablation zones. ConclusionsThe RF ablation coil device successfully produced large, uniform ablation volumes in ex vivo and in vivo settings in treatment times of less than 10minutes. Ex vivo and in vivo lesion sizes were not significantly different (P=.53), suggesting that the heating efficiency of this higher-frequency coil device may help to minimize the heat-sink effect of perfusion.