Image-guided preplanning workflow for high-dose-rate interstitial brachytherapy for gynecological malignancies.

PURPOSE: To demonstrate image-guided preplan workflows for high-dose-rate (HDR) brachytherapy for advanced gynecological malignancies. METHODS AND MATERIALS: Two different preplanning scenarios are presented: (1) CT- or MRI-based preplan with partial applicator in place; (2) Preplans generated from prior fractions. The first scenario can be applied to Syed-Neblett template-based implants or hybrid brachytherapy applicators, while the second scenario applies to hybrid applicators. Both scenarios use MRI or CT images acquired with the applicator in place to demonstrate tumor and applicator relative locations and therefore, provide the ability to show optimized suggested needle positions including the implant depths before the actual insertion. RESULTS: The preplanning techniques have demonstrated feasibility and shown five areas of potential improvement: (1) shorter procedure time, (2) decreased number of total needles inserted, (3) shorter physician tumor contour time, (4) shorter planning time, and (5) evaluation of appropriateness for brachytherapy. CONCLUSIONS: The use of image-guided brachytherapy preplanning improves clinical efficiency and is recommended for consideration for adaptation into clinical workflows for HDR interstitial and hybrid brachytherapy.

Technical note: Clinical evaluation of a newly released surface-guided radiation therapy system on DIBH for left breast radiation therapy.

BACKGROUND: It has been shown that a significant reduction of mean heart dose and left anterior descending artery (LAD) dose can be achieved through the use of DIBH for left breast radiation therapy. Surface-guided DIBH has been widely adopted during the last decade, and there are mainly three commercially available SGRT systems. The reports of the performance of a newly released SGRT system for DIBH application are currently very limited. PURPOSE: To evaluate the clinical performance of a newly released SGRT system on DIBH for left breast radiation therapy. METHODS: Twenty-five left breast cancer patients treated with DIBH utilizing Varian's Identify system were included (total 493-fraction treatments). Four aspects of the clinical performance were evaluated: Identify offsets of free breathing post patient setup from tattoos, Identify offsets during DIBH, Identify agreement with radiographic ports during DIBH, and DIBH reference surface re-capture post patient shifts. The systematic and random errors of free breathing Identify offsets post patient setup were calculated for each patient, as well as for offsets during DIBH. Radiographic ports were taken when the patient's DIBH position was within the clinical tolerance of (± 0.3 cm, ± 30 ), and these were then compared with treatment field DRRs. If the ports showed that the patient alignment did not agree with the DRRs within 3 mm, a patient shift was performed. A new reference surface was captured and verification ports were taken. RESULTS: The all-patient average systematic and random errors of Identify offsets for free breathing were within (0.4 cm, 1.50 ) post tattoo setup. The maximum per-patient systematic and random errors were (1.1 cm, 6.20 ) and (0.9 cm, 20 ), and the maximum amplitude of Identify offsets were (2.59 cm, 90 ). All 493-fraction DIBH treatments were delivered and successfully guided by the Identify SGRT system. The systematic and random errors of Identify offsets for DIBH were within (0.2 cm, 2.30 ). Seven patients needed re-captured surface references due to surface variation or position shifts based on the ports. All patient DIBH verification ports guided by Identify were approved by attending physicians. CONCLUSION: This evaluation showed that the Identify system performed effectively for surface-guided patient setup and surface-guided DIBH imaging and treatment delivery. The feature of color-coded real-time patient surface matching feedback facilitated the evaluation of the patient alignment accuracy and the adjustment of the patient position to match the reference.

Dosimetric Evaluation of Organs at Risk From SAVE Protocol.

PURPOSE: The objective of this work was to evaluate dosimetric characteristics to organs at risk (OARs) from short-course adjuvant vaginal cuff brachytherapy (VCB) in early endometrial cancer compared with standard of care (SOC) in a multi-institutional prospective randomized trial. METHODS AND MATERIALS: SAVE (Short Course Adjuvant Vaginal Brachytherapy in Early Endometrial Cancer Compared to Standard of Care) is a prospective, phase 3, multisite randomized trial in which 108 patients requiring VCB were randomized to an experimental short-course arm (11 Gy × 2 fractions [fx] to surface) and SOC arm. Those randomized to the SOC arm were subdivided into treatment groups based on treating physician discretion as follows: 7 Gy × 3 fx to 5 mm, 5 to 5.5 Gy × 4 fx to 5 mm, and 6 Gy × 5 fx to surface. To evaluate doses to OARs of each SAVE cohort, the rectum, bladder, sigmoid, small bowel, and urethra were contoured on planning computed tomography, and doses to OARs were compared by treatment arm. Absolute doses for each OAR and from each fractionation scheme were converted to 2 Gy equivalent dose (EQD23). Each SOC arm was compared with the experimental arm separately using 1-way analysis of variance, followed by pairwise comparisons using Tukey's honestly significant difference test. RESULTS: The experimental arm had significantly lower doses for rectum, bladder, sigmoid, and urethra compared with the 7 Gy × 3 and 5 to 5.5 Gy × 4 fractionation schemes; however, the experimental arm did not differ from the 6 Gy × 5 fractionation scheme. For small bowel doses, none of the SOC fractionation schemes were statistically different than the experimental. The highest EQD23 doses to the examined OARs were observed to come from the most common dose fractionation scheme of 7 Gy × 3 fx. With a short median follow-up of 1 year, there have been no isolated vaginal recurrences. CONCLUSIONS: Experimental short-course VCB of 11 Gy × 2 fx to the surface provides a comparable biologically effective dose to SOC courses. Experimental short-course VCB was found to reduce or be comparable to D2cc and D0.1cc EQD23 doses to rectum, bladder, sigmoid, small bowel, and urethra critical structures. This may translate into a comparable or lower rate of acute and late adverse effects.

Radical trachelectomy and adjuvant vaginal brachytherapy to preserve fertility in pediatric cervical adenocarcinoma.

PURPOSE: This case report describes the use of a trachelectomy and adjuvant vaginal brachytherapy for pediatric clear cell adenocarcinoma as definitive fertility-sparing treatment. METHODS AND MATERIALS: A previously healthy 8-year-old female presented with abdominal cramping and heavy vaginal bleeding. Diagnostic imaging revealed a 3.5 cm circumscribed cervical mass, with subsequent biopsy revealing clear cell adenocarcinoma. Fertility preserving treatment was requested. RESULTS: The patient underwent a radical trachelectomy, with final pathology demonstrating a close radial margin. Due to close margin, adjuvant radiotherapy with a vaginal cylinder was delivered to a total dose of 18 Gray in three fractions prescribed to a depth of 5 mm from the vaginal surface using iridium-192. With 2 years of follow-up, the patient continues to do well with no evidence of recurrence or late toxicity from treatment. CONCLUSIONS: Pediatric clear cell adenocarcinoma of the cervix is a rare occurrence that lacks clinical trials to guide effective treatment. Adjuvant vaginal brachytherapy following trachelectomy in a pediatric patient with clear cell adenocarcinoma of the cervix is feasible and well-tolerated.

Vaginal cuff brachytherapy for endometrial cancer: a review of major clinical trials with a focus on fractionation.

The use of vaginal cuff brachytherapy in the adjuvant management of endometrial cancer has increased over time. Recommendations from the American Brachytherapy Society, American Society of Radiation Oncology, and European Society for Medical Oncology help to guide the application of vaginal cuff brachytherapy. However, wide variation in practice remains regarding treatment techniques. This article reviews the use of vaginal cuff brachytherapy in the post-operative management of endometrial cancer. It covers risk stratification, treatment rationale, outcomes, and treatment planning recommendations with a specific focus on dose-fractionation regimens. The authors performed a thorough literature review of articles pertinent to the goals of this review. Also presented are early results of the Short Course Adjuvant Vaginal Cuff Brachytherapy in Early Endometrial Cancer Compared with Standard of Care (SAVE) trial of a two-fraction vaginal cuff brachytherapy regimen.Adjuvant vaginal cuff brachytherapy for early-stage endometrial cancer results in excellent disease control with minimal toxicity. The PORTEC-2 trial showed that vaginal cuff brachytherapy is non-inferior to external beam radiation for vaginal recurrence in patients at high-intermediate risk. Vaginal cuff brachytherapy may also be used as a boost following external beam radiation in combination with chemotherapy for high-risk histologies. Numerous techniques can be used for vaginal cuff brachytherapy, including various medical devices, dose-fractionation schedules, and treatment planning approaches. The early control results of the SAVE trial are promising and we are hopeful that this trial establishes two fraction regimens as a viable option for vaginal cuff brachytherapy.

Brachytherapy: common pitfalls.

Gynecologic radiation oncology is a demanding area of oncology requiring expertise in external beam and brachytherapy. Both physicians and physicists are called on to use their full complement of skills to employ state-of-the-art treatments to benefit patients. A wide variety of unusual presentations are frequent in gynecology, and hence, it is necessary to have a number of techniques available to offer the optimal treatments. The heterogeneity of treatments and the rarity of certain gynecological presentations lead to complexity and potential error. We reviewed previous gynecological high dose rate brachytherapy treatment images and plans for patients from the past decade and identified examples of common problems to share with the community. The strategies to prevent or recover from these pitfalls are also presented. With increasing number of applicator choices, it is critical for clinics to follow rigorous commissioning steps to ensure treatment process safety as described. The clinics should consider implementing a thorough on-boarding program and regular hands-on practice as a continuous quality improvement measure. The use of checklists can be invaluable and result in fewer human errors. Gynecological chart rounds that focus on brachytherapy are also encouraged. Lastly, an incident learning system to document small deviations that occur in the process, and a rigorous root cause analysis process could help prevent potential future incidents.

An Investigation of Radiation Treatment Learning Opportunities in Relation to the Radiation Oncology Electronic Medical Record: A Single Institution Experience.

PURPOSE: A modern radiation oncology electronic medical record (RO-EMR) system represents a sophisticated human-computer interface with the potential to reduce human driven errors and improve patient safety. As the RO-EMR becomes an integral part of clinical processes, it may be advantageous to analyze learning opportunities (LO) based on their relationship with the RO-EMR. This work reviews one institution's documented LO to: (1) study their relationship with the RO-EMR workflow, (2) identify best opportunities to improve RO-EMR workflow design, and (3) identify current RO-EMR workflow challenges. METHODS AND MATERIALS: Internal LO reports for an 11-year contiguous period were categorized by their relationship to the RO-EMR. We also identify the specific components of the RO-EMR used or involved in each LO. Additionally, contributing factor categories from the ASTRO/AAPM sponsored Radiation Oncology Incident Learning System's (RO-ILS) nomenclature was used to characterize LO directly linked to the RO-EMR. RESULTS: A total of 163 LO from the 11-year period were reviewed and analyzed. Most (77.2%) LO involved the RO-EMR in some way. The majority of the LO were the results of human/manual operations. The most common RO-EMR components involved in the studied LO were documentation related to patient setup, treatment session schedule functionality, RO-EMR used as a communication/note-delivery tool, and issues with treatment accessories. Most of the LO had staff lack of attention and policy not followed as 2 of the highest occurring contributing factors. CONCLUSIONS: We found that the majority of LO were related to RO-EMR workflow processes. The high-risk areas were related to manual data entry or manual treatment execution. An evaluation of LO as a function of their relationship with the RO-EMR allowed for opportunities for improvement. In addition to regular radiation oncology quality improvement review and policy update, automated functions in RO-EMR remain highly desirable.

Electronic charting of radiation therapy planning and treatment: Report of Task Group 262.

While most Radiation Oncology clinics have adopted electronic charting in one form or another, no consensus document exists that provides guidelines for safe and effective use of the Radiation Oncology electronic medical records (RO-EMR). Task Group 262 was formed to provide these guidelines as well as to provide recommendations to vendors for improving electronic charting functionality in future. Guidelines are provided in the following areas: Implementation and training for the RO-EMR, acceptance testing and quality assurance (QA) of the RO-EMR, use of the RO-EMR as an information repository, use of the RO-EMR as a workflow manager, electronic charting for brachytherapy and nonstandard treatments, and information technology (IT) considerations associated with the RO-EMR. The report was based on a literature search by the task group, an extensive survey of task group members on their respective RO-EMR practices, an AAPM membership survey on electronic charting, as well as group consensus.

Prevention of Radiation Therapy Treatment Deviations by a Novel Combined Biometric, Radiofrequency Identification, and Surface Imaging System.

PURPOSE: To evaluate the impact of Varian Identify, a novel combined radiofrequency identification, biometric and surface-matching technology, on its potential for patient safety and prevention of radiation therapy treatment deviations. METHODS AND MATERIALS: One hundred eight radiation therapy treatment deviation reports at our facility over the past 8 years were analyzed. Three major categories were defined based on the time point of occurrence: physician order deviations (19.4%), treatment-planning deviations (24.1%), and machine treatment deviations (56.5%). The impact of Identify on potential prevention of machine treatment deviations was analyzed. A failure mode and effects analysis was performed on the 5 most frequently occurring errors preventable with Identify. Safety analysis of the Identify system was reported based on 3.5 years of clinical data post-Identify system installation on 3 treatment vaults. RESULTS: Of the 61 machine treatment deviations, 47 (77%) were interpreted as being preventable by using Identify. Our failure mode and effects analysis showed reductions in all risk priority numbers post-Identify application. Safety analysis of the Identify system from our direct observation that for approximately 7 cumulative years of Identify use in 3 different treatment vaults, where 9 deviations would have been expected to occur over this combined period, zero machine treatment events occurred. CONCLUSIONS: The combination of Identify biometric, radiofrequency identification, and surface-matching technologies was observed to enable an effective process for enhancing safety and efficiency of radiation therapy treatment. A significant reduction in machine-related deviations was observed.

Evaluation of the effects of implementing a diode transmission device into the clinical workflow.

PURPOSE: This work investigated effects of implementing the Delta4 Discover diode transmission detector into the clinical workflow. METHODS: PDD and profile scans were completed with and without the Discover for a number of photon beam energies. Transmission factors were determined for all beam energies and included in Eclipse TPS to account for the attenuation of the Discover. A variety of IMRT plans were delivered to a Delta4 Phantom+ with and without the Discover to evaluate the Discover's effects on IMRT QA. An imaging QA phantom was used to assess the detector's effects on MV image quality. OSLDs placed on the Phantom+ were used to determine the detector's effects on superficial dose. RESULTS: The largest effect on PDDs after dmax was 0.5%. The largest change in beam profile symmetry and flatness was 0.2% and 0.1%, respectively. An average difference in gamma passing rates (2%/2 mm) of 0.2% was observed between plans that did not include the Discover in the measurement and calculation to plans that did include the Discover in the measurement and calculation. The Discover did not significantly change the MV image quality, and the largest observed increase in the relative superficial dose when the Discover was present was 1%. CONCLUSIONS: The effects the Discover has on the linac beam were found to be minimal. The device can be implemented into the clinic without the need to alter the TPS beam modeling, other than accounting for the device's attenuation. However, a careful workflow review to implement the Discover should be completed.

Using failure mode and effects analysis (FMEA) to generate an initial plan check checklist for improved safety in radiation treatment.

PURPOSE: To apply failure mode and effect analysis (FMEA) to generate an effective and efficient initial physics plan checklist. METHODS: A team of physicists, dosimetrists, and therapists was setup to reconstruct the workflow processes involved in the generation of a treatment plan beginning from simulation. The team then identified possible failure modes in each of the processes. For each failure mode, the severity (S), frequency of occurrence (O), and the probability of detection (D) was assigned a value and the risk priority number (RPN) was calculated. The values assigned were based on TG 100. Prior to assigning a value, the team discussed the values in the scoring system to minimize randomness in scoring. A local database of errors was used to help guide the scoring of frequency. RESULTS: Twenty-seven process steps and 50 possible failure modes were identified starting from simulation to the final approved plan ready for treatment at the machine. Any failure mode that scored an average RPN value of 20 or greater was deemed "eligible" to be placed on the second checklist. In addition, any failure mode with a severity score value of 4 or greater was also considered for inclusion in the checklist. As a by-product of this procedure, safety improvement methods such as automation and standardization of certain processes (e.g., dose constraint checking, check tools), removal of manual transcription of treatment-related information as well as staff education were implemented, although this was not the team's original objective. Prior to the implementation of the new FMEA-based checklist, an in-service for all the second checkers was organized to ensure further standardization of the process. CONCLUSION: The FMEA proved to be a valuable tool for identifying vulnerabilities in our workflow and processes in generating a treatment plan and subsequently a new, more effective initial plan checklist was created.

Comparison of surface guidance and target matching for image-guided accelerated partial breast irradiation (APBI).

PURPOSE: We investigate the feasibility of surface guided radiation therapy (SGRT) for accelerated partial breast irradiation (APBI) by comparing it with in-room, fan beam kV computed tomography on rails (CTOR) imaging of the targeted region. The uniqueness of our study is that all patients have multiple daily CTOR scans to compare corresponding SGRT AlignRT (VisionRT, United Kingdom) images to. METHODS/MATERIALS: Twelve patients receiving APBI were enrolled in this study. Before each treatment fraction, after patients were setup on tattoos, SGRT was performed using AlignRT, and then target matching was performance using CTOR. The average and maximum difference in shifts between SGRT and CTOR were calculated and analyzed for each patient, so as the correlation between surgical cavity size and shift difference. RESULTS: Our study showed that SGRT agreed well with CTOR for patients with small surgical cavity volume changes (<10%). There were nine patients who had a ≥5 mm maximum shift difference between SGRT and CTOR along any direction, and in two patients the difference was more than 10 mm (one patient with surgical cavity change 44.3% and one patient with 27 cc cavity volume decrease). All patients, except one, had a mean shift difference < 5 mm along any direction. CONCLUSION: For the patients studied here, SGRT appears to be a reasonable and potentially valuable image guidance approach for APBI for patients who experience small changes in surgical cavity volume (<10%) between CT simulation and treatment. However, there is potential for larger alignment errors (up to 11 mm) when using SGRT for patients who experience larger surgical cavity changes.

A systematic evaluation of the error detection abilities of a new diode transmission detector.

Transmission detectors meant to measure every beam delivered on a linear accelerator are now becoming available for monitoring the quality of the dose distribution delivered to the patient daily. The purpose of this work is to present results from a systematic evaluation of the error detection capabilities of one such detector, the Delta4 Discover. Existing patient treatment plans were modified through in-house-developed software to mimic various delivery errors that have been observed in the past. Errors included shifts in multileaf collimator leaf positions, changing the beam energy from what was planned, and a simulation of what would happen if the secondary collimator jaws did not track with the leaves as they moved. The study was done for simple 3D plans, static gantry intensity modulated radiation therapy plans as well as dynamic arc and volumetric modulated arc therapy (VMAT) plans. Baseline plans were delivered with both the Discover device and the Delta4 Phantom+ to establish baseline gamma pass rates. Modified plans were then delivered using the Discover only and the predicted change in gamma pass rate, as well as the detected leaf positions were evaluated. Leaf deviations as small as 0.5 mm for a static three-dimensional field were detected, with this detection limit growing to 1 mm with more complex delivery modalities such as VMAT. The gamma pass rates dropped noticeably once the intentional leaf error introduced was greater than the distance-to-agreement criterion. The unit also demonstrated the desired drop in gamma pass rates of at least 20% when jaw tracking was intentionally disabled and when an incorrect energy was used for the delivery. With its ability to find errors intentionally introduced into delivered plans, the Discover shows promise of being a valuable, independent error detection tool that should serve to detect delivery errors that can occur during radiotherapy treatment.

Do vaginal recurrence rates differ among adjuvant vaginal brachytherapy regimens in early-stage endometrial cancer?

PURPOSE: We sought to retrospectively examine clinical outcomes for three adjuvant vaginal high-dose-rate (HDR) brachytherapy regimens after hysterectomy for early-stage endometrial cancer. METHODS: Included were women of all ages from two independent hospital systems diagnosed with Stage I-II endometrial cancer of any grade between 2000 and 2016 who underwent hysterectomy followed by adjuvant vaginal cylinder HDR brachytherapy with either 7.0 Gy × 3 fractions prescribed to 0.5 cm vaginal depth, 6.5 Gy × 3 fractions prescribed to 0.5 cm vaginal depth, or 6.0 Gy × 5 fractions prescribed to the vaginal surface. Outcomes included vaginal recurrence (VR), pelvic recurrence, distant recurrence, locoregional recurrence, recurrence-free survival, and overall survival. RESULTS: Of the 348 women, 45 (13%) received 7.0 Gy × 3 fractions, 259 (74%) received 6.5 Gy × 3 fractions, and 44 (13%) received 6.0 Gy × 5 fractions. Women receiving 5-fraction brachytherapy were more likely to be younger with a higher performance status. At a median follow-up of 4.5 years, VR rates were 2.2%, 0.8%, and 4.5%, respectively. Multivariate analysis revealed no significant differences in the risks for VR among brachytherapy regimens. Risks for VR, pelvic recurrence, distant recurrence, locoregional recurrence, recurrence-free survival, and overall survival did not differ between propensity score-matched five- and 3-fraction brachytherapy cohorts. CONCLUSIONS: VR rates after hysterectomy and adjuvant vaginal brachytherapy for early-stage endometrial cancer were low and not significantly different by HDR dose fractionation.

Impact of prone versus supine positioning on small bowel dose with pelvic intensity modulated radiation therapy.

PURPOSE: To report the results of a prospective study that compares small bowel doses during prone and supine pelvic intensity modulated radiation therapy. METHODS AND MATERIALS: Ten patients receiving pelvic radiation therapy each had 2 intensity modulated radiation therapy plans generated: supine and prone on a belly board (PBB). Computed tomography on rails was performed weekly throughout treatment in both positions (10 scans per patient). After image fusion, doses to small bowel (SB) loops and clinical target volume were calculated for each scan. Changes between the planned and received doses were analyzed and compared between positions. The impact of bladder filling on SB dose was also assessed. RESULTS: Prone treatment was associated with significantly lower volumes of SB receiving ≥20 Gy. On average, prone on a belly board positioning reduced the volume of SB receiving a given dose of radiation by 28% compared with supine positioning. Target coverage throughout the treatment course was similar in both positions with an average minimum clinical target volume dose of 88% of the prescribed prone dose and 89% of the supine (P = .54). For supine treatment, SB dose was inversely correlated with bladder filling (P = .001-.013; P > .15 for prone). For 96% of treatments, the volume of SB that received a given dose deviated >10% from the plan. The deviation between the planned and delivered doses to SB did not differ significantly between the positions. CONCLUSIONS: Prone positioning on a belly board during pelvic IMRT consistently reduces the volume of SB that receives a broad range of radiation doses. Prone IMRT is associated with interfraction dose variation to SB that is similar to that of supine positioning. These findings suggest that prone positioning with daily image guided radiation therapy is an effective method for maximizing SB sparing during pelvic IMRT.

Brachytherapy Improves Survival in Stage III Endometrial Cancer With Cervical Involvement.

PURPOSE: To evaluate the survival benefit of adding vaginal brachytherapy (BT) to pelvic external beam radiation therapy (EBRT) in women with stage III endometrial cancer. METHODS AND MATERIALS: The National Cancer Data Base was used to identify patients with stage III endometrial cancer from 2004 to 2013. Only women who received adjuvant EBRT were analyzed. Women were grouped according to receipt of BT. Logistic regression modeling was used to identify predictors of receiving BT. Log-rank statistics were used to compare survival outcomes. Cox proportional hazards modeling was used to evaluate the effect of BT on survival. A propensity score-matched analysis was also conducted among women with cervical involvement. RESULTS: We evaluated 12,988 patients with stage III endometrial carcinoma, 39% of whom received EBRT plus BT. Women who received BT were more likely to have endocervical or cervical stromal involvement (odds ratios 2.03 and 1.77; P<.01, respectively). For patients receiving EBRT alone, the 5-year survival was 66% versus 69% with the addition of BT at 5 years (P<.01). Brachytherapy remained significantly predictive of decreased risk of death (hazard ratio 0.86; P<.01) on multivariate Cox regression. The addition of BT to EBRT did not affect survival among women without cervical involvement (P=.84). For women with endocervical or cervical stromal invasion, the addition of BT significantly improved survival (log-rank P<.01). Receipt of EBRT plus BT was associated with improved survival in women with positive and negative surgical margins, and receiving chemotherapy did not alter the benefit of BT. Propensity score-matched analysis results confirmed the benefit of BT among women with cervical involvement (hazard ratio 0.80; P=.01). CONCLUSIONS: In this population of women with stage III endometrial cancer the addition of BT to EBRT was associated with an improvement in survival for women with endocervical or cervical stromal invasion.

Comparison of surface matching and target matching for image-guided pelvic radiation therapy for both supine and prone patient positions.

We investigate the difference between surface matching and target matching for pelvic radiation image guidance. The uniqueness of our study is that all patients have multiple CT-on-rails (CTOR) scans to compare to corresponding AlignRT images. Ten patients receiving pelvic radiation were enrolled in this study. Two simulation CT scans were performed in supine and prone positions for each patient. Body surface contours were generated in treatment planning system and exported to AlignRT to serve as reference images. During treatment day, the patient was aligned to treatment isocenter with room lasers, and then scanned with both CTOR and AlignRT. Image-guidance shifts were calculated for both modalities by com-parison to the simulation CT and the differences between them were analyzed for both supine and prone positions, respectively. These procedures were performed for each patient once per week for five weeks. The difference of patient displace-ment between AlignRT and CTOR was analyzed. For supine position, five patients had an average difference of displacement between AlignRT and CTOR along any direction (vertical, longitudinal, and lateral) greater than 0.5 cm, and one patient greater than 1 cm. Four patients had a maximum difference greater than 1 cm. For prone position, seven patients had an average difference greater than 0.5 cm, and three patients greater than 1 cm. Nine patients had a maximum difference greater than 1 cm. The difference of displacement between AlignRT and CTOR was greater for the prone position than for the supine position. For the patients studied here, surface matching does not appear to be an advisable image-guidance approach for pelvic radiation therapy for patients with either supine or prone position. There appears to be a potential for large alignment discrepancies (up to 2.25 cm) between surface matching and target matching.

Brachytherapy improves survival in primary vaginal cancer.

PURPOSE: Prospective, randomized data does not exist to guide treatment in primary vaginal cancer (PVC). We evaluated the impact of brachytherapy on survival in women with PVC. METHODS AND MATERIALS: Women who received radiotherapy for PVC were identified using the Surveillance, Epidemiology, and End Result database. Two retrospective cohorts were created; women who received external beam radiotherapy (EBRT) alone and those who received brachytherapy (alone or in combination of EBRT). Nearest-neighbor propensity score matching was used to balance the groups according to measured covariates. Cox proportional hazard regression modeling was used to estimate the effect of receipt of brachytherapy on survival. RESULTS: Two thousand five hundred seventeen vaginal cancer patients were identified. Squamous cell carcinoma made up 75% of tumors. Median overall survival (OS) for patients receiving EBRT alone was 3.6years (95% CI, 3.0-4.2years) versus 6.1years (95% CI 5.2-7.2years) for patients receiving brachytherapy (p=<0.001). Cox proportional hazard model revealed decrease risk of death among patients that received brachytherapy in the matched cohort (HR 0.77; 95% CI 0.68-0.86). Brachytherapy reduced risk of death among patients in all stage groups. No patient demographic or tumor variables favored the use of EBRT alone. Brachytherapy was associated with a decreased risk of death for all FIGO stages. Brachytherapy benefited patients with squamous cell carcinoma (HR 0.80; 95% CI 0.70-0.92) and adenocarcinoma (HR 0.69; 95% CI 0.49-0.95). Tumors larger than 5cm had the greatest benefit from brachytherapy (HR 0.68; 95% CI 0.50-0.91). CONCLUSIONS: Brachytherapy should be encouraged for all suitable patients with PVC.

Detection of late radiation damage on left atrial fibrosis using cardiac late gadolinium enhancement magnetic resonance imaging.

PURPOSE: This is a proof-of-principle study investigating the feasibility of using late gadolinium enhancement magnetic resonance imaging (LGE-MRI) to detect left atrium (LA) radiation damage. METHODS AND MATERIALS: LGE-MRI data were acquired for 7 patients with previous external beam radiation therapy (EBRT) histories. The enhancement in LA scar was delineated and fused to the computed tomography images used in dose calculation for radiation therapy. Dosimetric and normal tissue complication probability analyses were performed to investigate the relationship between LA scar enhancement and radiation doses. RESULTS: The average LA scar volume for the subjects was 2.5 cm3 (range, 1.2-4.1 cm3; median, 2.6 cm3). The overall average of the mean dose to the LA scar was 25.9 Gy (range, 5.8-49.2 Gy). Linear relationships were found between the amount of radiation dose (mean dose) (R2 = 0.8514, P = .03) to the LA scar-enhanced volume. The ratio of the cardiac tissue change (LA scar/LA wall) also demonstrated a linear relationship with the level of radiation received by the cardiac tissue (R2 = 0.9787, P < .01). Last, the normal tissue complication probability analysis suggested a dose response function to the LA scar enhancement. CONCLUSIONS: With LGE-MRI and 3-dimensional dose mapping on the treatment planning system, it is possible to define subclinical cardiac damage and distinguish intrinsic cardiac tissue change from radiation induced cardiac tissue damage. Imaging myocardial injury secondary to EBRT using MRI may be a useful modality to follow cardiac toxicity from EBRT and help identify individuals who are more susceptible to EBRT damage. LGE-MRI may provide essential information to identify early screening strategy for affected cancer survivors after EBRT treatment.