Luke B. McLemore

Adaptation of the Stanford technique for treatment of bulky cutaneous T-cell lymphoma of the head

Electron beam radiation therapy is an effective treatment for cutaneous T-cell lymphoma (CTCL).1,2 The first description of total skin electron therapy came from Stanford University.1,3 Prolonged treatment to ≥3000 cGy in 6 to 7 weeks is not feasible for many patients in a palliative setting. Hypofractionated regimens are associated with high response rates.4-8 We describe a case of bulky CTCL of the head treated with a unique adaptation of the Stanford technique.

Technique for the administration of high-dose-rate brachytherapy to the bile duct using a nasobiliary catheter

PURPOSE Cholangiocarcinoma patients who are potential candidates for liver transplantation may be treated with high-dose-rate (HDR) brachytherapy using a minimally invasive nasobiliary catheter in an effort to escalate the radiotherapy dose to the tumor and maximize local control rates. This work describes the equipment, procedures, and quality assurance (QA) that enables successful administration. METHODS AND MATERIALS This work describes the nasobiliary catheter placement, simulation, treatment planning, treatment delivery, and QA. In addition, a chart review was performed of all patients who received endoscopic retrograde cholangiopancreatography for HDR bile duct brachytherapy at our institution from 2007 to 2017. The review evaluated how many patients were treated and the number of patients who could not be treated because of anatomic and/or equipment limitations. RESULTS From 2007 to 2017, 122 cholangiocarcinoma patients have been treated with HDR brachytherapy using a nasobiliary catheter. Three patients underwent catheter placement but did not receive brachytherapy treatment due to catheter migration between placement and treatment or because the HDR afterloader was unable to extend the source wire into the treatment site. Periodic QA is recommended for ensuring whether the HDR afterloader is capable of extending the source wire through an extensive and curved path. CONCLUSIONS Intraluminal HDR brachytherapy with a nasobiliary catheter can be successfully administered. Procedures and QA are described for ensuring safety and overcoming technical challenges.

A method to improve dose uniformity during total skin electron beam therapy in patients with pendulous breasts

Cutaneous lymphomas are particularly radiosensitive and amenable to palliative radiation therapy. Total skin electron beam therapy (TSEB) is effective for palliation of Sézary syndrome and cutaneous T-cell lymphoma with large body surface area involvement. Focal radiation therapy is often used for treatment of localized disease. Treatment of cutaneous T-cell lymphoma can often pose technical challenges that require creative, patient-specific solutions. The electron beam used in TSEB is superficially penetrating. Although technique-dependent variation exists in the depth of penetration, delivery of an effective dose is generally limited to a depth of less than 1 cm. The inframammary fold of a pendulous breast is generally deeper than 1 cm and therefore will not receive an adequate radiation dose when treated by this technique. The use of a thin brassiere, as suggested in American Association of Physicists Report 23, may overcome this problem in some patients. We report the use of a sling made from nylon stockings to suspend large, pendulous

Patient safety is improved with an incident learning system—Clinical evidence in brachytherapy

BACKGROUND AND PURPOSE Health leaders have advocated for incident learning systems (ILSs) to prevent errors, but there is limited evidence demonstrating that ILSs improve cancer patient safety. Herein, we report a long-term retrospective review of ILS reports for the brachytherapy practice at a large academic institution. MATERIAL AND METHODS Over a nine-year period, the brachytherapy practice was encouraged to report all standard operating procedure deviations, including low risk deviations. A multidisciplinary committee assigned root causes and risk scores to all incidents. Evidence based practice changes were made using ILS data, and relevant incidents were communicated to all staff in order to reduce recurrence rates. RESULTS 5258 brachytherapy procedures were performed and 2238 incidents were reported from 2007 to 2015. A ramp-up period was observed in ILS participation between 2007 (0.12 submissions/procedures) and 2011 (1.55 submissions/procedures). Participation remained stable between 2011 and 2015, and we achieved a 60% (p<0.001) decrease in the risk of dose error or violation of radiation safety policy and a 70% (p<0.001) decrease in frequency of high composite-risk scores. Significant decreases were also observed in incidents with root causes of poor communication (60% decrease, p<0.001) and poor quality of written procedures (59% decrease, p<0.001). CONCLUSIONS Implementation of an ILS in brachytherapy significantly reduced risk during cancer patient care. Safety improvements have been sustained over several years.

Report on use of a methodology for commissioning and quality assurance of a VMAT system.

Introduction Results of use of methodology for VMAT commissioning and quality assurance, utilizing both control point tests and dosimetric measurements are presented. Methods and Materials A generalizable, phantom measurement approach is used to characterize the accuracy of the measurement system. Correction for angular response of the measurement system and inclusion of couch structures are used to characterize the full range gantry angles desirable for clinical plans. A dose based daily QA measurement approach is defined. Results Agreement in the static vs. VMAT picket fence control point test was better than 0.5 mm. Control point tests varying gantry rotation speed, leaf speed and dose rate, demonstrated agreement with predicted values better than 1%. Angular dependence of the MatriXX array, varied over a range of 0.94–1.06, with respect to the calibration condition. Phantom measurements demonstrated central axis dose accuracy for un-modulated four field box plans was ≥2.5% vs. 1% with and without angular correction respectively with better results for VMAT (0.4%) vs. IMRT (1.6%) plans. Daily QA results demonstrated average agreement all three chambers within 0.4% over 9 month period with no false positives at a 3% threshold. Discussion The methodology described is simple in design and characterizes both the inherit limitations of the measurement system as well at the dose based measurements that may be directly related to patient plan QA.

SU‐E‐T‐376: Report on Use of a Methodology for Commissioning and Quality Assurance of a VMAT System

Introduction: Results of use of methodology for VMAT commissioning and quality assurance, utilizing both control point tests and dosimetric measurements are presented. Methods: A generalizable, phantom measurement approach is used to characterize the accuracy of the measurement system. Correction for angular response of the measurement system and inclusion of couch structures are used to characterize the full range gantry angles desirable for clinical plans. A dose based comprehensive daily QA measurement approach is defined. Results: Agreement in the static vs. VMAT picket fence control point test was better than 0.5 mm. Control point tests varying gantry rotation speed, leaf speed and dose rate, demonstrated agreement with predicted values better than 1%. Angular dependence of the MatriXX array, varied over a range of 0.94 –1.06, with respect to the calibration condition. Phantom measurements demonstrated central axis dose accuracy for un‐modulated four field box plans was =2.5 % vs. 1% with and without angular correction respectively with better results for VMAT (0.4%) vs. IMRT (1.6%) plans. Daily QA results demonstrated average agreement of all three chambers within 0.4% over 9 month period with no false positives at a 3% threshold. Conclusions: The methodology described is simple in design and characterizes both the inherit limitations of the measurement system as well at the dose based measurements that may be directly related to patient plan QA.