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BACKGROUND: The pancreas is a complex abdominal organ with many anatomical variations, and therefore automated pancreas segmentation from medical images is a challenging application. PURPOSE: In this paper, we present a framework for segmenting individual pancreatic subregions and the pancreatic duct from three-dimensional (3D) computed tomography (CT) images. METHODS: A multiagent reinforcement learning (RL) network was used to detect landmarks of the head, neck, body, and tail of the pancreas, and landmarks along the pancreatic duct in a selected target CT image. Using the landmark detection results, an atlas of pancreases was nonrigidly registered to the target image, resulting in anatomical probability maps for the pancreatic subregions and duct. The probability maps were augmented with multilabel 3D U-Net architectures to obtain the final segmentation results. RESULTS: To evaluate the performance of our proposed framework, we computed the Dice similarity coefficient (DSC) between the predicted and ground truth manual segmentations on a database of 82 CT images with manually segmented pancreatic subregions and 37 CT images with manually segmented pancreatic ducts. For the four pancreatic subregions, the mean DSC improved from 0.38, 0.44, and 0.39 with standard 3D U-Net, Attention U-Net, and shifted windowing (Swin) U-Net architectures, to 0.51, 0.47, and 0.49, respectively, when utilizing the proposed RL-based framework. For the pancreatic duct, the RL-based framework achieved a mean DSC of 0.70, significantly outperforming the standard approaches and existing methods on different datasets. CONCLUSIONS: The resulting accuracy of the proposed RL-based segmentation framework demonstrates an improvement against segmentation with standard U-Net architectures.
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BACKGROUND: High dose rate brachytherapy is commonly used in the treatment of prostate cancer. Treatment planning is often performed under transrectal ultrasound (US) guidance, but brachytherapy needles can be challenging to digitize due to the presence of poor US conspicuity and imaging artifacts. The plan accuracy and quality, however, are dependent on the proper visualization of the needles with millimeter accuracy. PURPOSE: This work describes a technique for generating a color overlay of needle locations atop the grayscale US image. Prototype devices were developed to produce vibrations in the brachytherapy needles that generate a high contrast color Doppler (CD) signal that highlights the needle locations with superior contrast and reduced artifacts. Denoted by the acronym color VISION (Vibrationally Induced Shimmering for Identifying an Object's Nature), the technology has the potential to improve applicator conspicuity and facilitate automated applicator digitization. METHODS: Three prototype vibrational devices with frequencies between 200-450 Hz were designed in-house and evaluated with needle implants in a phantom and cadaveric male pelvis using: (1) an actuator attached to the front of a prostate needle template; (2) an actuator attached to the top of the needle template; and (3) a hand-held actuator with a stylet, inserted directly into a needle's inner lumen. Acquired images were postprocessed in MATLAB to evaluate the potential for automated digitization. RESULTS: All prototype devices produced localized shimmering in implanted brachytherapy needles in both the axial and sagittal planes. The template mounted actuators provided better vibrational coupling and ease of operation than the stylet prototype. The Michelson contrast, or visibility, of the shimmering CD signal was 100% compared with ≤40% for B-mode imaging of a single needle. Proof-of-principle for automated applicator digitization using only the CD signal was demonstrated. CONCLUSIONS: The color VISION prototype devices successfully coupled mechanical vibrations into brachytherapy needles to generate US CD shimmering and accurately highlight brachytherapy needle locations. The high contrast and natively registered signal are promising for future work to automate the needle digitization and provide a real-time visual overlay of the applicator on the B-mode US image.
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Braquiterapia , Agujas , Braquiterapia/instrumentación , Braquiterapia/métodos , Humanos , Masculino , Ultrasonografía/instrumentación , Fantasmas de Imagen , Vibración/uso terapéutico , Radioterapia Guiada por Imagen/instrumentación , Radioterapia Guiada por Imagen/métodos , ColorRESUMEN
OBJECTIVE: To determine the association between pre-operative central subfield thickness (CST) and post-radiotherapy visual acuity (VA), cystoid macular edema (CME), and intravitreal anti-vascular endothelial growth factor (VEGF) requirement. DESIGN: Single-center retrospective study. PARTICIPANTS: Patients with plaque-irradiated extramacular choroidal melanoma treated between 11/11/2011 and 4/30/2021. Pre-operative CST difference between the affected and unaffected eye was used. Kaplan-Meier analysis and hazard ratios were calculated. RESULTS: Of 85 patients, pre-operative CST was greater in the melanoma-affected eye (vs. fellow eye) by mean of 20.4 µm (median 14.0, range - 60.0-182.0). Greater CST at presentation (vs. fellow eye) was associated with larger tumor diameter (p = 0.02), greater tumor thickness (p < 0.001), and more frequent tumor-related Bruch's membrane rupture (p = 0.006). On univariate analysis of outcome data, greater CST at presentation (vs. fellow eye) was associated with higher 5-year risk (1.09 [1.02-1.17], p = 0.02) of VA 20/200 or worse and increased (1.10 [1.01-1.20], p = 0.03) likelihood for anti-VEGF injections after plaque irradiation. There was no significant association with CME. The association between CST and VA outcome remained significant on multivariate analysis accounting for impact of tumor thickness and radiation dose to optic disc, while tumor distance to fovea was the only significant factor on multivariate analysis for anti-VEGF injections. CONCLUSION: Greater CST at presentation (vs. fellow eye) was associated with worse VA outcome following plaque radiotherapy for choroidal melanoma. Large-sized tumors may contribute to a higher intraocular VEGF burden, potentially leading to greater preoperative CST, which correlates with poor VA outcome post-plaque radiotherapy.
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Neoplasias de la Coroides , Edema Macular , Melanoma , Neoplasias de la Úvea , Humanos , Estudios Retrospectivos , Factor A de Crecimiento Endotelial Vascular , Melanoma/diagnóstico , Melanoma/radioterapia , Edema Macular/tratamiento farmacológico , Neoplasias de la Coroides/diagnóstico , Neoplasias de la Coroides/radioterapia , Agudeza Visual , Inyecciones Intravítreas , Inhibidores de la Angiogénesis , Tomografía de Coherencia ÓpticaRESUMEN
PURPOSE: Quantitative bibliometrics are increasingly used to evaluate faculty research productivity. This study benchmarks publication rates for radiation oncologists from highly ranked National Cancer Institute-designated cancer centers and reveals how productivity changes over the arc of a career and of the field over time. METHODS AND MATERIALS: Peer-reviewed articles from 1970 to 2022 were obtained using Scopus for the 348 radiation oncologists listed as faculty for the top 10 cancer hospitals ranked by US News and World Report in 2022. Bibliometrics were analyzed for authorships (AË), authorships where the individual was first or last author (FËL), the monograph equivalent of authorships (MËE), h-index, and ha-index (an analog to h-index using MËE in place of publications). Career start was defined as the year of first publication. Bibliometric inflation was explored by analyzing authorship and bibliometric changes between 1990 and 2022. RESULTS: Publication rates peak, with as much as a 500% increase, 20 to 25 years from the start of a career before declining until retirement. At career ages of 1, 10, 20, and 30 years, the median bibliometrics were AË = (1.5, 4.1, 6.5, 7.0) year-1, FËL = (0.5, 0.9, 1.2, 0.6) year-1, MËE= (0.2, 0.5, 0.7, 0.8) year-1, h-index = (1, 12, 22, 47), and ha-index = (0.4, 4.4, 6.9, 18.4). With regards to authorship patterns across eras, the median number of authors listed per paper increased by 240% between 1990 and 2022. Meanwhile, research productivity per individual as measured by FËL and MËE was unchanged. CONCLUSIONS: The research publication rates of the median radiation oncologist change substantially over the course of their career. Productivity improves steadily for more than 2 decades before peaking and declining. The culture of authorship has also changed between 1990 and 2022. The number of authors listed per paper has trended upwards, which has an inflationary effect on the number of authorships and h-index. Meanwhile, the rate of manuscripts published per faculty has not changed.
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Neoplasias , Oncólogos de Radiación , Humanos , Publicaciones , Bibliometría , Docentes , AutoriaRESUMEN
PURPOSE: Suboptimal ultrasound conspicuity of the brachytherapy applicator can lead to inaccurate image reconstructions of the applicator resulting in decreased tumor control or increased normal tissue dose. This feasibility study aims to improve ultrasound conspicuity of high-dose rate (HDR) brachytherapy needles by modifying the surface of the needles to produce a color Doppler twinkling signature. MATERIALS AND METHODS: Surface modifications of standard 17-gauge titanium HDR brachytherapy needles included laser-scribing, application of polymethyl methacrylate (PMMA), and coating with a commercially available echogenic coating. Laser-scribing was performed with variable widths (0.1-1 mm) and depths (10-100 µm). The echogenic coating was applied with 3 different thicknesses (27, 40, and 64 µm). Unmodified and modified needles were imaged under B-mode and color Doppler ultrasound in phantom and cadaver, and the signal strength was recorded. RESULTS: Laser-scribed, PMMA-coated, and echogenic-coated brachytherapy needles produced a twinkling signature along the needle shaft on color Doppler ultrasound. Twinkling was observed with laser-scribe depths >20 µm and widths >0.1 mm and from echogenic coatings 40 µm and 64 µm thick. Twinkling was not observed with unmodified needles. The twinkling signature had a spectral composition with a uniform magnitude between the velocities of 2 to 16 cm/s. CONCLUSIONS: Color Doppler ultrasound of surface-modified brachytherapy applicators may improve applicator conspicuity aiding applicator placement and digitization. HDR brachytherapy needles may be modified to produce the twinkling signature via laser-scribing, PMMA rings, or applying an echogenic coating.
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Braquiterapia , Masculino , Humanos , Braquiterapia/métodos , Polimetil Metacrilato , Próstata , Ultrasonografía , AgujasRESUMEN
Purpose: Purpose: Subtotal skin electron beam therapy may be an option for patients with cutaneous lymphoma receiving radiation therapy to treat large areas of their skin but may benefit from sparing specific areas that may have had previous radiation therapy, are of specific cosmetic concern, and/or show no evidence of disease. We report here on the design, implementation, and dosimetric characteristics of a reusable and transparent customizable shield for use with the large fields used to deliver total skin electron beam therapy at extended distance with a conventional linear accelerator. Methods and Materials: A shield was designed and manufactured consisting of acrylic blocks that can be mounted on a steel frame to allow patient-specific shielding. The dosimetry of the device was measured using radiochromic film. Results: The shield is easy to use and well-tolerated for patient treatment, providing minimal electron transmission through the shield with a sharp penumbra at the field edge, with no increase in x-ray dose. We report on the dosimetry of a commercial device that has been used to treat more than 30 patients to date. Conclusions: The customizable shield is well suited to providing patient-specific shielding for subtotal skin electron beam therapy.
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PURPOSE: To provide clinical guidance for centers wishing to implement photon spatially fractionated radiation therapy (SFRT) treatments using either a brass grid or volumetric modulated arc therapy (VMAT) lattice approach. METHODS: We describe in detail processes which have been developed over the course of a 3-year period during which our institution treated over 240 SFRT cases. The importance of patient selection, along with aspects of simulation, treatment planning, quality assurance, and treatment delivery are discussed. Illustrative examples involving clinical cases are shown, and we discuss safety implications relevant to the heterogeneous dose distributions. RESULTS: SFRT can be an effective modality for tumors which are otherwise challenging to manage with conventional radiation therapy techniques or for patients who have limited treatment options. However, SFRT has several aspects which differ drastically from conventional radiation therapy treatments. Therefore, the successful implementation of an SFRT treatment program requires the multidisciplinary expertise and collaboration of physicians, physicists, dosimetrists, and radiation therapists. CONCLUSIONS: We have described methods for patient selection, simulation, treatment planning, quality assurance and delivery of clinical SFRT treatments which were built upon our experience treating a large patient population with both a brass grid and VMAT lattice approach. Preclinical research and patient trials aimed at understanding the mechanism of action are needed to elucidate which patients may benefit most from SFRT, and ultimately expand its use.
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Neoplasias , Radioterapia de Intensidad Modulada , Humanos , Fraccionamiento de la Dosis de Radiación , Neoplasias/radioterapia , Dosificación Radioterapéutica , Radioterapia de Intensidad Modulada/métodosRESUMEN
Background and purpose: To evaluate the long-term outcome of accelerated partial breast irradiation utilizing intraoperatively placed applicator-based brachytherapy (ABB) in early-stage breast cancer. Materials and methods: From our prospective registry, 223 patients with pTis-T2, pN0/pN1mic breast cancer were treated with ABB. The median treatment duration including surgery and ABB was 7 days. The prescribed doses were 32 Gy/8 fx BID (n = 25), 34 Gy/10 fx BID (n = 99), and 21 Gy/3 fx QD (n = 99). Endocrine therapy (ET) adherence was defined as completion of planned ET or ≥ 80% of the follow-up (FU) period. Cumulative incidence of ipsilateral breast tumor recurrence (IBTR) was estimated and influencing factors for IBTR-free survival rate (IBTRFS) were analyzed. Results: 218/223 patients had hormone receptor-positive tumors, including 38 (17.0%) with Tis and 185 (83.0%) with invasive cancer. After a median FU of 63 months, 19 (8.5%) patients had recurrence [17 (7.6%) with an IBTR]. Rates of 5-year IBTRFS and DFS were 92.2% and 91.1%, respectively. The 5-year IBTRFS rates were significantly higher for post-menopausal women (93.6% vs. 66.4%, p = 0.04), BMI < 30 kg/m2 (97.4% vs. 88.1%, p = 0.02), and ET-adherence (97.5% vs. 88.6%, p = 0.02). IBTRFS did not differ with dose regimens. Conclusions: Postmenopausal status, BMI < 30 kg/m2, and ET- adherence predicted favorable IBTRFS. Our results highlight the importance of careful patient selection for ABB and encouragement of ET compliance.
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BACKGROUND: Applicator conspicuity in ultrasound-guided brachytherapy procedures is commonly impaired by imaging artifacts or non-ideal imaging geometry, which can slow down applicator position digitization and increase the geometric uncertainty of the delivered dose distribution. PURPOSE: The purpose of this study was to improve the conspicuity of high-dose rate (HDR) brachytherapy needles under B-mode ultrasound imaging by applying an echogenic surface coating. Our hypothesis was that an echogenic coating would reduce artifacts and improve needle visualization within regions of signal degradation. METHODS: In this study, 17-gauge, 25-cm long titanium HDR brachytherapy needles were coated with acoustically reflective microspheres over a 2.5 cm region starting from the needle tip. Three coating thicknesses (27 µm, 40 µm, 64 µm) were compared against an uncoated control needle. The coated and uncoated needles were imaged using B-mode ultrasound in a tissue-equivalent prostate phantom and in a cadaverous male pelvis using a transrectal probe. Needle conspicuity was assessed under multiple conditions: a single needle implant, an implant with multiple needles between the probe and the needle of interest, and an angled needle implant. All images were assessed qualitatively for needle conspicuity and the presence of artifacts and quantitatively using grey-scale image intensity values. RESULTS: The 64 µm echogenic coating reduced the magnitude of reverberation artifacts by 31 ± 14% and comet tail artifacts by 40%-70%. The echogenic coating also improved needle contrast, measured by the relative differences in signal intensity compared with the adjacent environment, when needles were angled up to 30° with respect to the transducer probe in the cadaver. The improvements in conspicuity and artifact reduction increased with increasing coating thickness. The performance of the needles coated with the 64 µm thickness was qualitatively superior and yielded high-contrast, well-circumscribed signals in the cadaverous male pelvis, even under situations where a needle was acoustically shadowed by multiple other needles. CONCLUSIONS: An echogenic surface coating reduced imaging artifacts and improved needle conspicuity under realistic clinical conditions for ultrasound-based prostate or gynecological brachytherapy. The improved conspicuity has the potential to improve the efficiency of needle placement and the accuracy of needle position digitization during brachytherapy procedures.
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Braquiterapia , Neoplasias de la Próstata , Masculino , Humanos , Braquiterapia/métodos , Ultrasonografía , Agujas , Próstata/diagnóstico por imagen , Fantasmas de Imagen , Neoplasias de la Próstata/diagnóstico por imagen , Neoplasias de la Próstata/radioterapiaRESUMEN
BACKGROUND: To determine risk factors for postradiation optic atrophy (PROA) after plaque radiotherapy for uveal melanoma. METHODS: A single center, retrospective cohort study of patients diagnosed with uveal melanoma involving choroid and/or ciliary body treated with plaque between January 1, 2008, and December 31, 2016. Outcomes included development of PROA with pallor alone or with concomitant neuroretinal rim thinning (NRT). Cox regression analysis was performed to identify risk factors for PROA. RESULTS: Of 78 plaque-irradiated patients, PROA developed in 41 (53%), with concomitant NRT in 15 (19%). Risk factors for PROA of any type included presentation with worse visual acuity (odds ratio [95% confidence interval] 5.6 [2.3-14.1], P < 0.001), higher baseline intraocular pressure (IOP; 14 vs 16 mm Hg) (1.1 [1.0-1.2], P = 0.03), shorter tumor distance to optic disc (1.3 [1.2-1.5], P < 0.001) and foveola (1.2 [1.1-1.3], P < 0.001), subfoveal subretinal fluid (3.8 [2.0-7.1], P < 0.001), greater radiation prescription depth (1.3 [1.1-1.6], P = 0.002), dose to fovea (point dose) (1.01 [1.01-1.02], P < 0.001), and mean (1.02 [1.02-1.03], P < 0.001) and maximum dose to optic disc per 1 Gy increase (1.02 [1.01-1.03], P < 0.001). On multivariate modeling, dose to disc, baseline IOP, and subfoveal fluid remained significant. Subanalysis revealed risk factors for pallor with NRT of greater mean radiation dose to disc (1.03 [1.01-1.05], P = 0.003), higher maximum IOP (17 vs 20 mm Hg) (1.4 [1.2-1.7], P < 0.001), and subfoveal fluid (12 [2-63], P = 0.004). CONCLUSION: PROA may result in NRT in addition to optic disc pallor. Risk factors for PROA included higher radiation dose to optic disc, higher baseline IOP, and subfoveal fluid. Higher maximum IOP contributed to concomitant NRT.
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Atrofia Óptica , Disco Óptico , Humanos , Presión Intraocular , Melanoma , Disco Óptico/patología , Palidez/patología , Estudios Retrospectivos , Neoplasias de la ÚveaRESUMEN
PURPOSE: This is a multi-institutional report on inter-observer and inter-instrument variation in the calibration of the absorbed dose rate for a planar 32P beta emitting brachytherapy source. Measurement accuracy is essential since the dose profile is steep and the source is used for the treatment of tumors that are located in close proximity to healthy nervous system structures. METHODS AND MATERIALS: An RIC-100 32P source was calibrated by three institutions using their own equipment and following their standard procedures. The first institution calibrated the source with an electron diode and EBT3 film. The second institution used an electron diode. The third institution used HD810 film. Additionally, each institution was asked to calibrate the source using an electron diode and procedure that was shared among all institutions and shipped along with the radiation source. The dose rate was reported in units of cGy*min-1 at a water equivalent depth of 1 mm. RESULTS: Close agreement was observed in the measurements from different users and equipment. The variation across all diode detectors and institutions had a standard deviation of 1.8% and maximum difference of 4.6%. The observed variation among two different diode systems used within the same institution had a mean difference of 1.6% and a maximum variation of 1.8%. The variations among film and diode systems used within the same institution had a mean difference of 2.9% and a maximum variation of 4.3% CONCLUSIONS: The absorbed dose rate measurement protocol of the planar beta-emitting 32P source permits consistent dosimetry across three institutions and five different electron diode and radiochromic film systems. The methodologies presented herein should enable measurement consistency among other clinical users, which will help ensure high quality patient treatments and outcomes analysis.
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Braquiterapia , Braquiterapia/métodos , Calibración , Dosimetría por Película , Humanos , Radiometría/métodos , Dosificación Radioterapéutica , AguaRESUMEN
PURPOSE: Brachytherapy is an essential technique to deliver radiation therapy and is involved in the treatment of multiple disease sites as monotherapy or as an adjunct to external beam radiation therapy. With a growing focus on the cost and value of cancer treatments as well as new payment models, it is essential that standardized quality measures and metrics exist to allow for straightforward assessment of brachytherapy quality and for the development of clinically significant and relevant clinical data elements. We present the American Brachytherapy Society consensus statement on quality measures and metrics for brachytherapy as well as suggested clinical data elements. METHODS AND MATERIALS: Members of the American Brachytherapy Society with expertise in disease site specific brachytherapy created a consensus statement based on a literature review and clinical experience. RESULTS: Key quality measures (ex. workup, clinical indications), dosimetric metrics, and clinical data elements for brachytherapy were evaluated for each modality including breast cancer, cervical cancer, endometrial cancer, prostate cancer, keratinocyte carcinoma, soft tissue sarcoma, and uveal melanoma. CONCLUSIONS: This consensus statement provides standardized quality measures and dosimetric quality metrics as well as clinical data elements for each disease site to allow for standardized assessments of brachytherapy quality. Moving forward, a similar paradigm can be considered for external beam radiation therapy as well, providing comprehensive radiation therapy quality measures, metrics, and clinical data elements that can be incorporated into new payment models.
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Braquiterapia , Oncología por Radiación , Neoplasias de la Úvea , Benchmarking , Braquiterapia/métodos , Humanos , Masculino , Indicadores de Calidad de la Atención de Salud , Estados UnidosRESUMEN
PURPOSE: A customized Collaborative Ocular Melanoma Study (COMS)-style eye plaque may provide superior dosimetric coverage compared with standard models for certain intraocular tumor locations and shapes. This work provides a recipe for developing and validating such customized plaques. METHODS AND MATERIALS: The concept-into-clinical treatment process for a customized COMS-style eye plaque begins with a CAD model design that meets the specifications of the radiation oncologist and surgeon based on magnetic resonance, ultrasound, and clinical measurements, as well as a TG-43 hybrid heterogeneity-corrected dose prediction to model the dose distribution. Next, a 3D printed plastic prototype is created and reviewed. After design approval, a Modulay plaque is commercially fabricated. Quality assurance (QA) is subsequently performed to verify the physical measurements of the Modulay and Silastic and also includes dosimetric measurement of the calibration, depth dose, and dose profiles. Sterilization instructions are provided by the commercial fabricator. This customization procedure and QA methodology is demonstrated with a narrow-slotted plaque that was recently constructed for the treatment of a circumpapillary (e.g., surrounding the optic disk) ocular tumor. RESULTS: The production of a customized COMS-style eye plaque is a multistep process. Dosimetric modeling is recommended to ensure that the design will meet the patient's needs, and QA is essential to confirm that the plaque has the proper dimensions and dose distribution. The customized narrow-slotted plaque presented herein was successfully implemented in the clinic, and provided superior dose coverage of juxtapapillary and circumpapillary tumors compared with standard or notched COMS-style plaques. Plaque development required approximately 30 h of physicist time and a fabrication cost of $1500. CONCLUSION: Customized eye plaques may be used to treat intraocular tumors that cannot be adequately managed with standard models. The procedure by which a customized COMS-style plaque may be designed, fabricated, and validated was presented along with a clinical example.
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Braquiterapia , Neoplasias del Ojo , Melanoma , Braquiterapia/métodos , Humanos , Radioisótopos de Yodo , Melanoma/radioterapia , Dosificación RadioterapéuticaRESUMEN
PURPOSE: Eye plaques are widely used for ocular melanoma and provide an effective alternative to enucleation with adequate tumor control. A COMS plaque utilizes a Silastic insert for precise positioning of the radioactive seeds with respect to the scleral surface of the eye; however, due to manufacturing variability, the insert may unintentionally increase or decrease the distance between the sources and tumor. The purpose of this work is to provide guidance in measuring and identifying outliers in Silastic inserts. The importance of regular quality assurance (QA) is illustrated in an experience where a systematic problem was detected and the manufacturer's 22-mm mold was corrected. METHODS: A detailed description of the molds and manufacturing process used to produce Silastic inserts is provided, including photographs of the process steps. The variability in Silastic insert production was evaluated by measuring the thickness of 124 Silastic inserts. An estimate of how the observed Silastic thickness discrepancies impact the dose to the tumor and critical eye structures was performed using homogeneous dose calculations. A standard QA protocol was developed to guide the clinical user. RESULTS: Thickness of the measured Silastic inserts ranged from 1.22 to 2.67 mm, demonstrating variation from the 2.25 mm standard. Six of the 22-mm inserts were outliers (Δthickness >3 standard deviations) and were excluded from the statistics. The outliers were investigated with the help of the manufacturer, who discovered that a systematic error was accidentally introduced into the 22-mm mold. CONCLUSIONS: Due to manufacturing errors or variability, the Silastic inserts used in COMS eye plaques may be thicker or thinner than the design standard. Such variations may impact tumor control or increase the risk of normal tissue side effects. A standardized QA program is recommended to detect variations and communicate unusual findings to the manufacturer.
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Braquiterapia , Neoplasias del Ojo , Dimetilpolisiloxanos , Neoplasias del Ojo/radioterapia , Humanos , Radioisótopos de Yodo , Método de Montecarlo , Dosificación RadioterapéuticaRESUMEN
PURPOSE: Radiation side effects and visual outcome for uveal melanoma patients managed with plaque radiotherapy are dependent on the radiation dose administered to the tumor and nearby healthy tissues. We have developed an open-source software tool, EyeDose, to simplify and standardize tumor and critical structure dose reporting for Collaborative Ocular Melanoma Study eye plaques. METHODS AND MATERIALS: EyeDose is a MATLAB-based program that calculates point dose and volume dose metrics for standard models of the tumor and critical ocular structures. It uses published three-dimensional dose distributions for eye plaques, calculated with Monte Carlo methods, which are oriented with respect to the eye using the tumor's position on a fundus diagram. A standard model for the ocular structures was created using published measurements and patient CT scans. EyeDose reports radiation statistics for the fovea, optic disc, lens, lacrimal gland, retina, and tumor. The dosimetric margin for implant placement uncertainty is also calculated. RESULTS: EyeDose calculations were validated against previously published Monte Carlo results for eight different tumor positions, including the dose to the fovea, optic disc, lacrimal gland, lens, and along the central axis. EyeDose accepts a spreadsheet input for rapidly processing large retrospective patient data sets, with an average run time of <40 s per patient. EyeDose is published as an open-source tool for easy adaptation at different institutions. CONCLUSIONS: EyeDose calculates radiation statistics for Collaborative Ocular Melanoma Study eye plaque patients with Monte Carlo accuracy and without a treatment planning system. EyeDose streamlines data collection for large retrospective studies and can also be used prospectively to assess plaque applicability.
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Braquiterapia , Neoplasias del Ojo , Melanoma , Disco Óptico , Braquiterapia/métodos , Neoplasias del Ojo/radioterapia , Humanos , Radioisótopos de Yodo , Melanoma/radioterapia , Método de Montecarlo , Dosis de Radiación , Radiometría , Dosificación Radioterapéutica , Planificación de la Radioterapia Asistida por Computador , Estudios RetrospectivosRESUMEN
BACKGROUND/OBJECTIVES: To report clinical outcomes of modified Collaborative Ocular Melanoma Study IRIS (COMS IRIS) plaques for treatment of iris, iridociliary, and ciliary body melanoma. SUBJECTS/METHODS: Retrospective, single-centre cohort study of iris melanoma treated with COMS IRIS plaque radiotherapy from July 26, 2010 to October 15, 2018. Medical records were reviewed for demographics, tumour features, treatment parameters, and clinical outcomes. RESULTS: There were 22 cases, diagnosed at mean age of 59 years (median 65, range 21-85 years) with female sex in 14 (64%). Presenting tumour features included Snellen visual acuity (VA) ≥ 20/40 in 18 (82%) cases, mean largest tumour basal diameter 4.7 mm (median 3.9, range 2.3-13.8 mm) and thickness 1.7 mm (median 1.6 mm, range 0.8-3.9 mm), iris stromal seeding in 3 (14%) cases, angle seeding in 16 (73%), and ciliary body involvement in 13 (59%). After mean follow-up of 51 months (median 44, range 4-113 months), Snellen VA was ≥20/40 in 14 (64%) cases, with local tumour recurrence in 2 (9%), and enucleation in 2 (9%). The 3-year Kaplan-Meier estimated risk of local tumour recurrence was 7%. The most common radiation side effects were cataract in 17 (77%) patients and dry eye in 5 (23%). Systemic metastasis occurred in no cases, and 1 (5%) non-melanoma-related death due to natural causes was observed at last follow-up. CONCLUSIONS: COMS IRIS plaques are effective for treatment of iris, iridociliary, and ciliary body melanoma with modest VA outcomes and low frequency of local tumour recurrence, enucleation, radiation side effects, and systemic metastasis.
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Braquiterapia , Neoplasias del Iris , Melanoma , Adulto , Anciano , Anciano de 80 o más Años , Cuerpo Ciliar , Estudios de Cohortes , Enucleación del Ojo , Femenino , Estudios de Seguimiento , Humanos , Neoplasias del Iris/radioterapia , Neoplasias del Iris/cirugía , Melanoma/cirugía , Persona de Mediana Edad , Estudios Retrospectivos , Resultado del Tratamiento , Adulto JovenRESUMEN
PURPOSE: Historically, the standard of care for total skin electron beam therapy (TSEBT) delivered 30 to 36 Gy over 5 to 10 weeks. Given the high risk of relapse, a majority of patients require additional treatments. Therefore, attempts to use a shortened course of TSEBT have been investigated. METHODS AND MATERIALS: We conducted a single-institution retrospective review to evaluate disease response, control, and toxicity using a low-dose, hypofractionated course of TSEBT (HTSEBT) in patients with mycosis fungoides. RESULTS: Forty patients received 57 courses of HTSEBT. Median dose (Gy)/fractionation was 12/3, spanning a median time of 2.4 weeks. Overall response rate of patients assessed (n = 54) was 100%. Thirty-one courses (57.4%) resulted in a complete response and 23 courses (42.6%) resulted in a partial response. Cumulative incidence of progressive skin disease at 3 months was 37.2%, at 6 months, 56.9%, and at 1 year, 81.5%. Of the 40 patients treated with a first course of HTSEBT, 31 received subsequent courses of radiotherapy. Cumulative incidence of subsequent treatment was 28.0% at 3 months, 46.8% at 6 months, and 70.0% at 1 year. Patients who underwent repeat courses of HTSEBT continued to have similar treatment responses to repeat courses without increased toxicities. Toxicities from all courses were acceptable with the exception of 1 patient, who experienced grade 4 skin toxicity (moist desquamation requiring hospitalization). CONCLUSIONS: Low-dose HTSEBT provides good palliation in patients with cutaneous T-cell lymphoma with a satisfactory response and toxicity profile. HTSEBT allows therapy to be completed in far fewer treatments. Low-dose HTSEBT is an appropriate treatment option for patients unable to come for daily treatment. HTSEBT provides a way to decrease exposure to other patients and staff during public health emergencies such as the coronavirus disease 2019 (COVID-19) pandemic.
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Linfoma Cutáneo de Células T/radioterapia , Piel/efectos de la radiación , Tomografía Computarizada por Rayos X/métodos , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Masculino , Persona de Mediana Edad , Dosificación Radioterapéutica , Estudios Retrospectivos , Piel/patologíaRESUMEN
PURPOSE: A Pareto Navigation and Visualization (PNaV) tool is presented for interactively constructing a high-dose-rate (HDR) brachytherapy treatment plan by navigating and visualizing the multidimensional Pareto surface. PNaV aims to improve treatment planning time and quality and is generalizable to any number of dose-volume histogram (DVH) and convex dose metrics. METHODS AND MATERIALS: Pareto surface visualization and navigation were demonstrated for prostate, breast, and cervix HDR brachytherapy sites. A library of treatment plans was created to span the Pareto surfaces over a 30% range of doses in each of five DVH metrics. The PNaV method, which uses a nonnegative least-squares model to interpolate the library plans, was compared against pure optimization for 11,250 navigated plans using data envelopment analysis. The visualization of the metric trade-offs was accomplished using numerically estimated partial derivatives to plot the local curvature of the Pareto surface. PNaV enables the user to control both the magnitude and direction of the trade-off during navigation. RESULTS: Proof of principle of PNaV was demonstrated using a graphical user interface with visualization tools to enabled rapid plan selection and a quantitative review of metric trade-offs. PNaV produced deliverable plans with DVH metrics within < 0.4%, 0.6%, and 1.1% (95% confidence interval) of the Pareto surface using plan libraries with nominal plan spacing of 10%, 15%, and 30% in each metric dimension, respectively. The interpolation used for the navigation executed in 0.1 s. The fast interpolation allows for quick and efficient exploration of trade-off options by the physician, after an initial preprocessing step to generate the library. CONCLUSIONS: Generation, visualization, and navigation of the Pareto surface were validated for brachytherapy treatment planning. The PNaV method enables efficient and informed decision-making for radiotherapy.
Asunto(s)
Braquiterapia , Neoplasias de la Mama/radioterapia , Neoplasias de la Próstata/radioterapia , Planificación de la Radioterapia Asistida por Computador/métodos , Neoplasias del Cuello Uterino/radioterapia , Algoritmos , Femenino , Humanos , Masculino , Conceptos Matemáticos , Dosificación RadioterapéuticaRESUMEN
Purpose:To introduce a new optimization algorithm that improves DVH results and is designed for the type of heterogeneous dose distributions that occur in brachytherapy.Methods:The new optimization algorithm is based on a prior mathematical approach that uses mean doses of the DVH metric tails. The prior mean dose approach is referred to as conditional value-at-risk (CVaR), and unfortunately produces noticeably worse DVH metric results than gradient-based approaches. We have improved upon the CVaR approach, using the so-called Truncated CVaR (TCVaR), by excluding the hottest or coldest voxels in the structure from the calculations of the mean dose of the tail. Our approach applies an iterative sequence of convex approximations to improve the selection of the excluded voxels. Data Envelopment Analysis was used to quantify the sensitivity of TCVaR results to parameter choice and to compare the quality of a library of 256 TCVaR plans created for each of prostate, breast, and cervix treatment sites with commercially-generated plans.Results:In terms of traditional DVH metrics, TCVaR outperformed CVaR and the improvements increased monotonically as more iterations were used to identify and exclude the hottest/coldest voxels from the optimization problem. TCVaR also outperformed the Eclipse-Brachyvision TPS, with an improvement in PTVD95% (for equivalent organ-at-risk doses) of up to 5% (prostate), 3% (breast), and 1% (cervix).Conclusions:A novel optimization algorithm for HDR treatment planning produced plans with superior DVH metrics compared with a prior convex optimization algorithm as well as Eclipse-Brachyvision. The algorithm is computationally efficient and has potential applications as a primary optimization algorithm or quality assurance for existing optimization approaches.
Asunto(s)
Braquiterapia , Neoplasias de la Próstata , Algoritmos , Braquiterapia/métodos , Humanos , Masculino , Dosificación Radioterapéutica , Planificación de la Radioterapia Asistida por Computador/métodosRESUMEN
PURPOSE: The purpose of the study was to develop and evaluate an automated digitization algorithm for high-dose-rate cervix brachytherapy, with the goal of reducing the duration of treatment planning, staff resources, variability, and potential for human error. METHODS: An automated digitization algorithm was developed and retrospectively evaluated using treatment planning data from 10 patients with cervix cancer who were treated with a titanium tandem and ovoids applicator set. Applicators were segmented, without human interaction, by thresholding CT images to isolate high-density voxels and assigning the voxels to applicator and nonapplicator structures using HDBSCAN, a density-based linkage clustering algorithm. The applicator contours were determined from the centroid of the clustered voxels on each image slice and written to a treatment plan file. Automated contours were evaluated against manual digitization using distance and dosimetric metrics. RESULTS: A close agreement between automatic and manual digitization was observed. The mean magnitude of contour disagreement for 10 patients equaled 0.3 mm. Hausdorff distances were ≤1.0 mm. The applicator tip coordinates had submillimeter agreement. The median and mean dose volume histogram parameter differences were less than or equal to 1% for high-risk clinical target volume D90, high-risk clinical target volume D95, bladder D2cc, rectum D2cc, large bowel D2cc, and small bowel D2cc. The average execution time for the automated algorithm was less than 30 s. CONCLUSION: The digitization of titanium tandem and ovoids applicators for high-dose-rate brachytherapy treatment planning can be automated using straightforward thresholding and clustering algorithms. The adoption of automated digitization is expected to improve the consistency of treatment plans and reduce the duration of treatment planning.