Amin Mirhadi

Current Role of Radiation Therapy for Bladder Cancer

Radiation therapy continues to expand its role in the management of bladder cancer. Utilization of chemoradiation as part of the management increases the likelihood of keeping the native bladder and has a positive impact on quality of life, without compromising cure. There remains sustained interest in the concept of bladder conservation as an organ-sparing approach that is potentially equivalent to radical cystectomy as regards disease-specific survival. In addition, radiation therapy may play a meaningful role in the management of non-muscle-invasive bladder cancer by reducing the likelihood of local recurrence and preventing or delaying cystectomy. Recently, techniques of radiation therapy have improved considerably and the role of radiation therapy has subsequently expanded and led to better outcomes, as has a better understanding of the biology of fractionation and tumor response.

Current status of radiation therapy for bladder cancer.

The role of radiation therapy in the management of muscle-invasive bladder cancer has evolved tremendously over the past several decades. Early on, radiation therapy alone was utilized as the preferred method of bladder preservation. Unfortunately, the results with this approach have been suboptimal. More recently, several protocols have been developed using a combined modality approach with chemotherapy. This has opened the door once again to the concept of bladder conservation as a potentially equivalent approach to radical cystectomy. While it is unlikely that a randomized trial comparing radical cystectomy with bladder preservation and chemoradiotherapy will be performed, the latter treatment strategy is gaining more support among practitioners. In selected patients with muscle-invasive bladder cancer, bladder-preservation approaches can achieve high rates of complete response, acceptable disease control and excellent long-term bladder function. The key to success for such programs is the careful selection of patients with favorable clinical features and close monitoring of the treatment response during therapy. Aggressive transurethral resection of bladder tumor to debulk disease and early referral for cystectomy in nonresponding patients are also highly critical for a successful outcome.

Surgical Excision and Adjuvant Brachytherapy vs External Beam Radiation for the Effective Treatment of Keloids: 10-Year Institutional Retrospective Analysis

Background Surgically excised keloids reportedly recur at a rate of >45%. Post-excision radiation (RT) has been delivered via external beam radiotherapy (EBRT) or interstitial high dose rate (HDR) brachytherapy. Despite historical data showing 10% to 20% keloid recurrences with post-excision RT, there is a paucity of high-quality evidence comparing keloid recurrences between the two RT modalities. Objectives We performed the largest single-institution case-control retrospective study (2004-2014) of keloid recurrence rates and complications between post-excision EBRT and HDR brachytherapy. Methods One-hundred and twenty-eight patients, with 264 keloid lesions, were treated by excision alone (n = 28), post-excision EBRT (n = 197), or post-excision HDR brachytherapy (n = 39). Patient and keloid recurrence data were analyzed using mixed effect Cox regression modeling with a statistical threshold of P < .05. Results Fifty-four percent of keloids recurred after surgical excision alone (9-month median follow up); 19% of keloids recurred with post-excision EBRT (42-month median follow up); 23% of keloids recurred with post-excision brachytherapy (12-month median follow up). Adjuvant EBRT and brachytherapy each showed significant control of keloid recurrence compared to excision alone (P < .01). EBRT significantly delayed the time of keloid recurrence over brachytherapy by a mean difference of 2.5 years (P < .01). Conclusions Post-excision RT shows significant reduction in keloid recurrence compared to excision alone. While the recurrence control rates are not statistically different between EBRT and brachytherapy, keloids treated with EBRT recurred significantly later than those treated by HDR brachytherapy by a mean of 2.5 years. Further workup with a randomized control study will help to refine optimal adjuvant RT treatment. Level of Evidence: 3

Clinical experience using a video‐guided spirometry system for deep inhalation breath‐hold radiotherapy of left‐sided breast cancer

The purpose was to report clinical experience of a video‐guided spirometry system in applying deep inhalation breath‐hold (DIBH) radiotherapy for left‐sided breast cancer, and to study the systematic and random uncertainties, intra‐ and interfraction motion and impact on cardiac dose associated with DIBH. The data from 28 left‐sided breast cancer patients treated with spirometer‐guided DIBH radiation were studied. Dosimetric comparisons between free‐breathing (FB) and DIBH plans were performed. The distance between the heart and chest wall measured on the digitally reconstructed radiographs (DRR) and MV portal images, dDRR(DIBH) and dport(DIBH), respectively, was compared as a measure of DIBH setup uncertainty. The difference (Δd) between dDRR(DIBH) and dport(DIBH) was defined as the systematic uncertainty. The standard deviation of Δd for each patient was defined as the random uncertainty. MV cine images during radiation were acquired. Affine registrations of the cine images acquired during one fraction and multiple fractions were performed to study the intra‐ and interfraction motion of the chest wall. The median chest wall motion was used as the metric for intra‐ and interfraction analysis. Breast motions in superior–inferior (SI) direction and “AP” (defined on the DRR or MV portal image as the direction perpendicular to the SI direction) are reported. Systematic and random uncertainties of 3.8 mm and 2 mm, respectively, were found for this spirometer‐guided DIBH treatment. MV cine analysis showed that intrafraction chest wall motions during DIBH were 0.3 mm in “AP” and 0.6 mm in SI. The interfraction chest wall motions were 3.6 mm in “AP” and 3.4 mm in SI. Utilization of DIBH with this spirometry system led to a statistically significant reduction of cardiac dose relative to FB treatment. The DIBH using video‐guided spirometry provided reproducible cardiac sparing with minimal intra‐ and interfraction chest wall motion, and thus is a valuable adjunct to modern breast treatment techniques. PACS number: 87.55.kh, 87.55.ne, 87.55.tg

TU‐F‐17A‐06: Motion Stability and Dosimetric Impact of Spirometer‐Based DIBH‐RT of Left‐Sided Breast Cancer

PURPOSE Patients undergoing radiotherapy (RT) for left-sided breast cancer have increased risk of coronary artery disease. Deep Inhalation Breath Hold assisted RT (DIBH-RT) is shown to increase the geometric separation of the target area and heart, reducing cardiac radiation dose. The purposes of this study are to use Cine MV portal images to determine the stability of spirometer-guided DIBH-RT and examine the dosimetric cardiopulmonary impact of this technique. METHODS Twenty consecutive patients with left-sided breast cancer were recruited to the IRB-approved study. Free-breathing (FB) and DIBH-CTs were acquired at simulation. Rigid registration of the FB-CT and DIBH-CT was performed using primarily breast tissue. Treatment plans were created for each FB-CT and DIBH-CT using identical paired tangent fields with field-in-field or electronic compensation techniques. Dosimetric evaluation included mean and maximum (Dmax) doses for the left anterior descending artery (LAD), mean heart dose, and left lung V20. Cine MV portal images were acquired for medial and lateral fields during treatment. Analysis of Cine images involved chest wall segmentation using an algorithm developed in-house. Intra- and inter-fractional chest wall motion were determined through affine registration to the first frame of each Cine. RESULTS Dose to each cardiac structure evaluated was significantly (p<0.001) reduced with the DIBH plans. Mean heart dose decreased from 2.9(0.9-6.6) to 1.6(0.6-5.3) Gy; mean LAD dose from 16.6(3-43.6) to 7.4(1.7-32.7) Gy; and LAD Dmax from 35.4 (6.1-53) to 18.4(2.5-51.2) Gy. No statistically significant reduction was found for the left lung V20. Average AP and SI median chest wall motion (intrafractional) was 0.1 (SD=0.9) and 0.5 (SD=1.1) mm, respectively. Average AP inter-fractional chest wall motion was 2.0 (SD=1.4) mm. CONCLUSION Spirometer-based DIBH treatments of the left breast are reproducible both inter- and intra-fractionally, and provide a statistically and potentially clinically useful dosimetric advantage to cardiac structures.

Discriminating lung adenocarcinoma from lung squamous cell carcinoma using respiration induced tumor shape changes

Based on 4D-CT, we aimed to characterize the pattern of morphological changes in lung tumors during respiration, and investigated its potential in non-invasively differentiating lung adenocarcinoma (AC) and squamous cell carcinoma (SCC). We applied a 3D surface analysis on 22 tumors (13 AC, 9 SCC) to investigate the tumor regional morphological fluctuations in response to respiration phases. Tumor surface vertices among ten respiratory phases were matched using surface-based registration, and the shape descriptors (ρ and detJ) were calculated and tracked across respiration stages in a regionally aligned scenario. Pair-wise group comparisons were performed between lung AC and SCC subtypes, in terms of ratios of maximal shape changes as well as correlation coefficients between tumor shape and respiratory stage indicators from the lung. AC type tumors had averaged larger surface measurements at exhale than at inhale, and these surface measurements were negatively correlated with lung volumes across respiratory stages. In contrast, SCC type tumors had averaged smaller surface measurements at exhale than at inhale, and the correlations with lung volumes were positive. The group differences in maximal shape changes as well as correlations were both statistically significant (p  <  0.05). We developed a non-invasive lung tumor sub-type detection pipeline based on respiration-induced tumor surface deformation. Significant differences in deformation patterns were detected between lung AC and SCC. The derived surface measurements may potentially serve as a new non-invasive imaging biomarker of lung cancer subtypes.

SU‐E‐J‐151: An Off‐Line QA Tool for Evaluating Reproducibility of Deep Inhalation Breath‐Hold Treatment for Breast Radiotherapy

Purpose: To develop an off‐line QA tool for evaluating reproducibility of deep inhalation breath hold (DIBH) breast treatment using a spirometer‐based breathing control system with video guidance. Methods: Tangential beam plans (open medial field; lateral IMRT field) used for whole breast radiation with DIBH‐guided by a spirometer‐based breathing control system have been studied. An imaging sequence was set‐up at the treatment machine to acquire multiple (>15) EPID image frames during beam‐on with source‐to‐imager distance 150cm. Images were exported from the EPID and imported into an off‐line QA tool developed in‐house for evaluation of intra‐and inter‐fractional uncertainties for DIBH treatments. The user defines a region of interest (ROI) (e.g., expander, clip(s), chestwall) on the first (reference) image. A rectangular imaging template is created from the ROI with a defined expansion (e.g., 1cm). The template is then matched to each of the following image frames using cross‐correlation. Template movement is used to estimate breast motion during one or multiple breath‐hold sessions. The breath‐hold lung volume information is extracted from the spirometer and compared to the corresponding motion curve estimated from the EPID images. Results: Motions of different regions of the breast can be visualized and shown to be constant within 1mm at the imager (∼.7mm in the breast) for some patients. Both drifting and random motions can be identified on individual patients on specific days. Off‐line analysis of these data may provide a useful tool to assure that individual patients are adequately performing the DIBH technique, and to identify patients who require new margins or planning strategies. Conclusion: An off‐line QA motion evaluation tool has been designed for DIBH breast treatment, and is an effective method for evaluation of DIBH reproducibility both intra‐and inter‐fraction.