Chance Matthiesen

The Efficacy of Radiotherapy in the Treatment of Orbital Pseudotumor

PURPOSE To review institutional outcomes for patients treated with external-beam radiotherapy (EBRT) for orbital pseudotumor. METHODS AND MATERIALS This is a single-institution retrospective review of 20 orbits in 16 patients diagnosed with orbital pseudotumor that received EBRT at the University of Oklahoma, Department of Radiation Oncology. Treated patients had a median follow-up of 16.5 months. RESULTS Fifteen patients (93.7%) were initially treated with corticosteroids. Eight had recurrence after steroid cessation, six were unable to taper corticosteroids completely or partially, and one experienced progression of symptoms despite corticosteroid therapy. Fourteen patients (87.5%) initially responded to radiotherapy indicated by clinical improvement of preradiation symptoms and/or tapering of corticosteroid dose. Mean EBRT dose was 20 Gy (range, 14-30 Gy). Thirteen patients (81.2%) continued to improve after radiation therapy. Patient outcomes were complete cessation of corticosteroid therapy in nine patients (56.3%) and reduced corticosteroid dose in four patients (25%). Radiotherapy did not achieve long-term control for three patients (18.7%), who still required preradiation corticosteroid dosages. Three patients received retreatment(s) of four orbits, of which two patients achieved long-term symptom control without corticosteroid dependence. One patient received retreatment to an orbit three times, achieving long-term control without corticosteroid dependence. No significant late effects have been observed in retreated patients. CONCLUSIONS Radiotherapy is an effective treatment for acute symptomatic improvement and long-term control of orbital pseudotumor. Orbital retreatment can be of clinical benefit, without apparent increase in morbidity, when initial irradiation fails to achieve complete response.

Use of stereotactic body radiation therapy for medically inoperable multiple primary lung cancer

Introduction: To review outcomes of medically inoperable patients treated with stereotactic body radiation therapy (SBRT) for multiple primary lung cancer (MPLC).

Intensity modulated radiation therapy (IMRT) for the treatment of unicentric Castlemans disease: a case report and review of the use of radiotherapy in the literature

Intensity modulated radiation therapy (IMRT) for the treatment of unicentric Castlemans disease: a case report and review of the use of radiotherapy in the literature Background. Surgical resection is considered standard therapy for cases of resectable unicentric Castlemans disease (UCD). Unresectable cases of UCD do not have a consensus regarding the optimal treatment approach, but have utilized steroids, observation, chemotherapy, and radiotherapy. Here we discuss a patient presentation of UCD treated with an advanced radiotherapy technique, IMRT. Case report. A 47 year old female was found to have an intra-thoracic posterior UCD and was determined not to be a good surgical candidate. She was referred for radiotherapy and was treated using IMRT to a total dose of 4320 cGy in 180 cGy fractions including a scheduled 10 day break. Following the break, the patients treatment was replanned at which the initial treatment volume was reduced by 50.9% for the duration of the treatment course. Radiation Therapy Oncology Group (RTOG) grade III pneumonitis developed which was managed medically. Neither disease progression nor late effects have occurred. Conclusions. The use of IMRT and planned treatment break was successful in the treatment of a case of UCD, and should be considered for other unresectable cases.

The role of radiotherapy for T4 non-melanoma skin carcinoma

Introduction: To review outcomes of patients treated with radiotherapy (RT) for T4 non‐melanoma skin cancer (NMSC).

Dosimetric and radiobiologic comparison of 3D conformal, IMRT, VMAT and proton therapy for the treatment of early‐stage glottic cancer

This study aims to compare dosimetrically and radiobiologically 3D conformal, intensity modulated radiation therapy (IMRT), RapidArc (RA) volumetric modulated arc therapy and proton therapy techniques for early‐stage glottic cancer.

Gross tumour volume variations in primary non-small-cell lung cancer during the course of treatment with stereotactic body radiation therapy.

We aim to quantify the variations in the gross tumour volume (GTV) during a course of stereotactic body radiotherapy (SBRT) and determine its impact on dosimetric coverage of the GTV.

Radiotherapy in treatment of carcinoma of the parotid gland, an approach for the medically or technically inoperable patient

Introduction: Initial surgical resection is considered the standard of care for patients diagnosed with tumours involving the salivary glands. We reviewed our institutional outcomes of patients treated with initial radiation therapy (RT) for diagnosed carcinoma of the parotid gland.

Using an advanced radiation therapy technique for T4 squamous cell carcinoma of the face.

BACKGROUND Patients with locally advanced skin cancer often present an uncommon and unique treatment challenge. Surgical resection and reconstruction with an acceptable cosmetic outcome is difficult for larger lesions with deep infiltration into subcutaneous tissues. Radiation therapy has been shown to be an effective treatment modality for advanced non-melanoma skin cancers, with cure rates ranging 50-100%. In this case report, we discuss the efficacy and outcome of treatment using an advanced radiation therapy technique to a large T4 squamous cell carcinoma of the face. MAIN OBSERVATIONS The patient responded favorably to the advanced radiation treatment course, and achieved a clinical complete response to therapy. No further intervention was required. Advanced radiation therapy techniques offered treatment advantages that resulted in greater tumor dose escalation and minimizing of patient morbidity. CONCLUSIONS Patients with advanced skin cancers of the head and neck should be considered for definitive radiation therapy using advanced treatment techniques. The use of definitive RT only for tumors deemed unresectable, or for inoperable patients at presentation deserves reconsideration. Further investigation is warranted.

SU-E-T-652: Quantification of Dosimetric Uncertainty of I-125 COMS Eye Plaque

Purpose: To compare dosimetrically three plan calculation systems (Plato, Varian Brachytherapy, and in-house-made Excel) available for I-125 COMS eye plaque treatment with measurement. Methods: All systems assume homogeneous media and calculations are based on a three-dimensional Cartesian coordinates, Plato and Brachytherapy Planning are based on AAPM TG-43 and the in-house Excel program only on inverse square corrections. Doses at specific depths were measured with EBT3 Gafchromic film from a fully loaded and a partially loaded 16 mm plaque (13 and 8 seeds respectively, I-125, model 6711 GE, Oncura). Measurements took place in a water tank, utilizing solid water blocks and a 3D-printed plaque holder. Taking advantage that gafchromic film has low energy dependence, a dose step wedge was delivered with 6 MV photon beam from a Varian 2100 EX linac for calibration. The gray-scale to dose in cGy was obtained with an Epson Expression 10000 XL scanner in the green channel. Treatment plans were generated for doses of 2200 cGy to a depth of 7 mm, and measurements were taken on a sagittal plane. Results: The calculated dose at the prescription point was 2242, 2344, and 2211 cGy with Excel, Brachyvision and Plato respectively for a fully loaded plaque, for the partially loaded plaque the doses were 2266, 2477, and 2193 cGy respectively. At 5 mm depth the doses for Brachyvision and Plato were comparable (3399 and 3267 cGy respectively), however, the measured dose in film was 3180 cGy which was lower by as much as 6.4% in the fully loaded plaque and 7.6% in the partially loaded plaque. Conclusion: Careful methodology and calibration are essential when measuring doses at specific depth due to the sensitivity and rapid dose fall off of I-125.

Quantitative evaluation of correlation of dose and FDG-PET uptake value with clinical chest wall complications in patients with lung cancer treated with stereotactic body radiation therapy

The aim of this study was to investigate quantitatively the dosimetric factors that increase the risk of clinical complications of rib fractures or chest wall pain after stereotactic body radiation therapy (SBRT) to the lung. The correlations of clinical complications with standard-uptake values (SUV) and FDG-PET activity distributions from post-treatment PET-imaging were studied. Mean and maximum doses from treatment plans, FDG-PET activity values on post-SBRT PET scans and the presence of clinical complications were determined in fifteen patients undergoing 16 SBRT treatments for lung cancer. SBRT treatments were delivered in 3 to 5 fractions using 5 to 7 fields to prescription doses in the range from 39.0 to 60.0 Gy. The dose and FDG-PET activity values were extracted from regions of interest in the chest wall that matched anatomically. Quantitative evaluation of the correlation between dose deposition and FDG-PET activity was performed by calculating the Pearson correlation coefficient using pixel-by-pixel analysis of dose and FDG-PET activity maps in selected regions of interest associated with clinical complications. Overall, three of fifteen patients developed rib fractures with chest wall pain, and two patients developed pain symptoms without fracture. The mean dose to the rib cage in patients with fractures was 37.53 Gy compared to 33.35 Gy in patients without fractures. Increased chest wall activity as determined by FDG-uptake was noted in patients who developed rib fractures. Enhanced activity from PET-images correlated strongly with high doses deposited to the chest wall which could be predicted by a linear relationship. The local enhanced activity was associated with the development of clinical complications such as chest wall inflammation and rib fracture. This study demonstrates that rib fractures and chest wall pain can occur after SBRT treatments to the lung and is associated with increased activity on subsequent PET scans. The FDG-PET activity provides a useful parameter that can be used clinically to predict chest wall complication in lung patients.