OUTER FOVEAL DEFECTS IN TYPE-2 MACULAR TELANGIECTASIA.

PURPOSE: To report characteristics of outer foveal defects (OFDs) in type-2 macular telangiectasia (MacTel) on spectral domain optical coherence tomography. METHODS: This was a single-center observational study. From a registry of 745 patients with MacTel, patients with OFDs were characterized. All patients underwent multimodal imaging including color fundus photography, confocal blue reflectance, fundus autofluorescence, and spectral domain optical coherence tomography. Staging of eyes was done using the Gass and Blodi classification. Spectral domain optical coherence tomography characteristics in the central 1 mm of the macula in eyes with OFD are reported. RESULTS: Outer foveal defect was observed in 21 eyes of 15/745 (2%) patients with MacTel. These defects were bilateral in 6/15 (40%) patients and seen in stage 2 MacTel eyes. In order of prevalence, foveal parameters seen in OFD included hyper-reflective dots in outer retina in 19/21 (90%), ellipsoid zone loss in 18/21 (86%) eyes, interdigitation zone loss in 17/21 (81%) eyes, outer retinal hyporeflective cavitation in 14 (67%) eyes, hyporeflective cavitation at foveal pit in 8 (38%) eyes, and loss of external limiting membrane in 1 (5%) eye. The mean baseline length of the foveal ellipsoid zone loss was 240.17 ± 117.249 µm. The mean baseline central subfield thickness was 155.43 ± 17.215 µm. A total of 8/11 eyes (73%) showed an increase in size of OFD on follow-up. CONCLUSION: Outer foveal defect in MacTel eyes is characterized predominantly by foveal loss of ellipsoid zone and interdigitation zone with relative preservation of external limiting membrane.

EARLY SPECTRAL-DOMAIN OPTICAL COHERENCE TOMOGRAPHY BIOMARKERS TO CONFIRM FELLOW EYE CHANGES IN ASYMMETRIC TYPE-2 MACULAR TELANGIECTASIA: A Case-Control Study (India Macular Telangiectasia Report 1).

PURPOSE: To evaluate the earliest spectral-domain optical coherence tomography markers in fellow eyes of asymmetric Type-2 macular telangiectasia (MacTel). METHODS: A multicentered case-control study of spectral-domain optical coherence tomography images captured on Spectralis Heidelberg Engineering, Germany, comparing features of fellow eyes of patients with asymmetric clinical presentation of MacTel with 50 age-matched control subjects. RESULTS: Of 649 patients, 28 (4.3%) with MacTel presented with asymmetric features. The mean age of the MacTel patients was 63.5 (12.4) years with female predilection (4:1). Mean best-corrected visual acuity of the unaffected eye was 0.2 logarithm of the minimum angle of resolution (20/32 Snellen equivalent). The mean central subfoveal thickness in the unaffected MacTel eyes was 194 (SD, 38) µm, and the temporal retinal thickness was 204 (SD, 43) µm. These parameters were significantly thinner than those of control subjects in whom mean central subfoveal thickness was 273 (SD, 26) µm (P = 0.001). Presence of hyperreflective outer retinal dots was found in 92.8% of the unaffected MacTel eyes. These hyperreflective dots were scattered, punctate, nonconfluent, and confined to the outer retinal layers of foveal and parafoveal region. CONCLUSION: Although these cases presented with advanced presentation of MacTel features in only one eye, temporal retinal thinning and presence of hyperreflective outer retinal dots in the fellow eye can be considered as the earliest signs of MacTel.

Need for Vitreous Surgeries in Proliferative Diabetic Retinopathy in 10-Year Follow-Up: India Retinal Disease Study Group Report No. 2.

INTRODUCTION: To report the 10-year rate of vitrectomies and the associated factors in people with proliferative diabetic retinopathy (PDR) from a multicentric cohort of people with diabetes mellitus. METHODS: Ten centres in India with established vitreoretinal (VR) services for over 10 years were invited to provide long-term data on PDR. People with Type 1 or 2 diabetes with a clinical diagnosis of active PDR in 1 or both eyes were included. Baseline data collected included age, sex, duration of diabetes, source of referral and best-corrected visual acuity, and diabetic retinopathy status in both eyes. Available follow-up data included the numbers of panretinal photocoagulation (PRP) sessions, cataract surgery, treatment of diabetic macular oedema, use of anti-vascular endothelial growth factor (VEGF) therapy, vitrectomy with or without retinal surgeries over 10 years. RESULTS: Over 10 years, 89% needed supplemental PRP after initial complete PRP. One-third required retinal surgery, 16% needed intravitreal injection. Men (74.5%) had significant higher risk for vitreous (VR) surgery. Of the group with low-risk PDR, 56.8% did not require VR surgery, p < 0.001. Of the patients who underwent cataract surgery and had intravitreal anti-VEGF injections, 78.5 and 28.2% needed subsequent vitreous (VR) surgery, p = 0.006 and <0.0001, respectively. Independent predictors of need for vitreoretinal surgery included those who underwent cataract surgery and those with poor baseline visual acuity (logMAR). Eyes at lower risk for VR surgery included the eyes previously treated with PRP and low-risk PDR at baseline. CONCLUSION: Despite initial "complete" PRP, one-third of our study cohort needed vitrectomies over 10 years, highlighting that these patients require regular follow-up for a long period of time.

Practice patterns and recommendations for pediatric image-guided radiotherapy: A Children's Oncology Group report.

This report by the Radiation Oncology Discipline of Children's Oncology Group (COG) describes the practice patterns of pediatric image-guided radiotherapy (IGRT) based on a member survey and provides practice recommendations accordingly. The survey comprised of 11 vignettes asking clinicians about their recommended treatment modalities, IGRT preferences, and frequency of in-room verification. Technical questions asked physicists about imaging protocols, dose reduction, setup correction, and adaptive therapy. In this report, the COG Radiation Oncology Discipline provides an IGRT modality/frequency decision tree and the expert guidelines for the practice of ionizing image guidance in pediatric radiotherapy patients.

TIMING AND OUTCOME OF SURGERY FOR PERSISTENT MACULAR HOLE.

PURPOSE: To evaluate the efficacy and optimum timing for resurgery in case of persistent macular hole (MH). METHODS: Twenty-five eyes of 25 patients who underwent fluid-air exchange with intravitreal C3F8 for persistent MH after vitrectomy + internal limiting membrane peeling + SF6 were included in the study. Best-corrected visual acuity, optical coherence tomography features including base diameter and configuration of MH, and time duration between the two surgeries were noted. RESULTS: Patients who underwent resurgery within 3 months of the first surgery had better anatomical closure rate compared with those who underwent resurgery after 3 months (P < 0.05). Significant improvement was seen in best-corrected visual acuity in eyes with closed MH. Eyes having MH with irregular edges on optical coherence tomography had better anatomical closure rates compared with the eyes having MH with round edges. CONCLUSION: Patients undergoing repeat gas injection within 3 months of the primary surgery for persistent MH have better anatomical closure rates compared with late intervention.

Clinical implementation, logistics and workflow guide for MRI image based interstitial HDR brachytherapy for gynecological cancers.

Interstitial brachytherapy (IBT) is often utilized to treat women with bulky endometrial or cervical cancers not amendable to intracavitary treatments. A modern trend in IBT is the utilization of magnetic resonance imaging (MRI) with a high dose rate (HDR) afterloader for conformal 3D image-based treatments. The challenging part of this procedure is to properly complete many sequenced and co-related physics preparations. We presented the physics preparations and clinical workflow required for implementing MRI-based HDR IBT (MRI-HDR-IBT) of gynecologic cancer patients in a high-volume brachytherapy center. The present document is designed to focus on the clinical steps required from a physicist's standpoint. Those steps include: (a) testing IBT equipment with MRI scanner, (b) preparation of templates and catheters, (c) preparation of MRI line markers, (d) acquisition, importation and registration of MRI images, (e) development of treatment plans and (f) treatment evaluation and documentation. The checklists of imaging acquisition, registration and plan development are also presented. Based on the TG-100 recommendations, a workflow chart, a fault tree analysis and an error-solution table listing the speculated errors and solutions of each step are provided. Our workflow and practice indicated the MRI-HDR-IBT is achievable in most radiation oncology clinics if the following equipment is available: MRI scanner, CT (computed tomography) scanner, MRI/CT compatible templates and applicators, MRI line markers, HDR afterloader and a brachytherapy treatment planning system capable of utilizing MRI images. The OR/procedure room availability and anesthesiology support are also important. The techniques and approaches adopted from the GEC-ESTRO (Groupe Européen de Curiethérapie - European Society for Therapeutic Radiology and Oncology) recommendations and other publications are proven to be feasible. The MRI-HDR-IBT program can be developed over time and progressively validated through clinical experience, this document is expected to serve as a reference workflow guideline for implementing and performing the procedure.

Feasibility and accuracy of UF/NCI phantoms and Monte Carlo retrospective dosimetry in children treated on National Wilms Tumor Study protocols.

PURPOSE: This pilot study was done to determine the feasibility and accuracy of University of Florida/National Cancer Institute (UF/NCI) phantoms and Monte Carlo (MC) retrospective dosimetry and had two aims: (1) to determine the anatomic accuracy of UF/NCI phantoms by comparing 3D organ doses in National Wilms Tumor Study (NWTS) patient-matched UF/NCI phantoms to organ doses in corresponding patient-matched CT scans and (2) to compare infield and out-of-field organ dosimetry using two dosimetry methods-standard radiation therapy (RT) treatment planning systems (TPS) and MC dosimetry in these two anatomic models. METHODS: Twenty NWTS patient-matched Digital Imaging and Communications in Medicine (DICOM) files of UF/NCI phantoms and CT scans were imported into the Pinnacle RT TPS. The NWTS RT fields (whole abdomen, flank, whole lung, or a combination) and RT doses (10-45 Gy) were reconstructed in both models. Both TPS and MC dose calculations were performed. For aim 1, the mean doses to the heart, kidney, thyroid gland, testes, and ovaries using TPS and MC in both models were statistically compared. For aim 2, the TPS and MC dosimetry for these organs in both models were statistically compared. RESULTS: For aim 1, there was no significant difference between phantom and CT scan dosimetry for any of the organs using either TPS or MC dosimetry. For aim 2, there was a significant difference between TPS and MC dosimetry for both CT scan and phantoms for all organs. Although the doses for infield organs were similar for both TPS and MC, the doses for near-field and out-of-field organs were consistently higher for 90% to 100% of MC doses; however, the absolute dose difference was small (<1 Gy). CONCLUSIONS: This pilot study has demonstrated that the patient-matched UF/NCI phantoms together with MC dosimetry is an accurate model for performing retrospective 3D dosimetry in large-scale epidemiology studies such as the NWTS.

DVH Analytics: A DVH database for clinicians and researchers.

In this study, we build a vendor-agnostic software application capable of importing and analyzing non-image-based DICOM files for various radiation treatment modalities (i.e., DICOM RT Dose, RT Structure, and RT Plan files). Dose-volume histogram (DVH) and planning data are imported into a SQL database, and methods are provided to manage, edit, view, and download data. Furthermore, the software provides various analytical tools for plan evaluations, plan comparisons, benchmarking, and plan outcome predictions. DVH Analytics is developed using Python, including libraries such as pydicom, dicompyler, psycopg2, SciPy, Statsmodels, and Bokeh for parsing DICOM files, computing DVHs, communicating with a PostgreSQL database, performing statistical analyses, and creating a web-based user interface. This software is open-source and compatible with Windows, Mac OS, and Linux. For proof-of-concept, a database with over 3,000 DVHs from a single physician's head & neck practice was built. From these data, differences in means, correlations, and temporal trends in dose to multiple organs-at-risk (OARs) were observed. Furthermore, an example of the predictive regression tool is reported, where a model was constructed to predict maximum dose to brainstem based on minimum distance from planning target volume (PTV) and treatment beam source-to-skin distance (SSD). With DVH Analytics, we have developed a free, open-source software program to parse, organize, and analyze non-image-based DICOM data for use in a radiation oncology setting. Furthermore, this software can be used to generate statistical models for the purposes of quality control or outcome predictions and correlations.

SULFURHEXAFLUORIDE (SF6) VERSUS PERFLUOROPROPANE (C3F8) GAS AS TAMPONADE IN MACULAR HOLE SURGERY.

PURPOSE: To compare outcomes of macular hole surgery using sulfurhexafluoride (SF6) versus perfluoropropane (C3F8) gas. METHODS: This is a retrospective, interventional, comparative study. A total of 177 eyes of 166 patients operated over a 3-year period for idiopathic macular holes were included. Sixty-seven eyes had tamponade with SF6 gas (Group 1), whereas 111 eyes received C3F8 (Group 2) as the tamponading agent. The primary outcome measure was the macular hole closure rate. Statistical analysis was done using SPSSv16. RESULTS: Spectral domain optical coherence tomography-based stagewise distribution of macular holes were similar across both groups (P = 0.99). The hole closure rate was 57/66 (86.4%) with SF6 and 96/111 (86.5%) with C3F8 gas (P = 0.98). Subanalysis demonstrated no significant difference in closure rates regarding macular hole size, stage, or duration. Best-corrected visual acuity improved by a mean of 0.28 logMAR in the SF6 group (P = 0.00) and 0.42 logMAR in the C3F8 group, corresponding to 3 lines and 4 lines of improvement, respectively, on the Early Treatment Diabetic Retinopathy Study chart (P < 0.05). The difference was not significant (P = 0.06). Rise in intraocular pressure was higher in the C3F8 group (P < 0.05). Progression of cataract was also greater in the C3F8 group (83.3 vs.73.9%), but it was not statistically significant (P = 0.20). Resurgery was done in 9/177 eyes. The closure rate with C3F8 and SF6 reinjections was 3/4 (75%) and 1/5 (20%). Moreover, anatomical hole closure after resurgeries was better in Group 1 (4/5 eyes) than in Group 2 (0/4 eyes). CONCLUSION: The macular hole closure rate was similar with sulfurhexafluoride and perfluoropropane, irrespective of hole size, stage, or duration. However, sulfurhexafluoride exhibited a decreased incidence of cataract and ocular hypertension with shorter tamponade duration. Perfluoropropane may have a role as the preferred endotamponading agent in failed primary surgeries.

SPECTRAL DOMAIN OPTICAL COHERENCE TOMOGRAPHY-BASED MICROSTRUCTURAL ANALYSIS OF RETINAL ARCHITECTURE POST INTERNAL LIMITING MEMBRANE PEELING FOR SURGERY OF IDIOPATHIC MACULAR HOLE REPAIR.

PURPOSE: Spectral domain optical coherence tomography-based analysis of retinal architecture after internal limiting membrane peeling for macular hole surgery. METHODS: Prospective, interventional study. Fifty eyes underwent the surgical procedure with minimum internal limiting membrane peel of 3 mm diameter. Automatic segmentation software was used to assess individual layers preoperatively and postoperatively, 1.5 millimeters medial and lateral to fovea at 3 months postoperative visit. Main outcome measures were final central macular thickness and variation in individual retinal layer thickness. RESULTS: Mean central macular thickness postoperatively was 201 microns. Retinal thickening was observed, 1.5 mm medial to fovea (P < 0.01) with significant increment in thickness of inner nuclear layer (P < 0.01), whereas significant retinal thinning was observed 1.5 mm temporal to fovea (P < 0.01) with maximum thinning observed in ganglion cell layer (P < 0.01). Ganglion cell and inner plexiform were the only layers to demonstrate thinning on both sides of the fovea. External limiting membrane (ELM), inner segment outer segment junction (ISOS) and cone outer segment tips zone (COST) restoration was seen in 100%, 69%, and 17% of eyes. Best corrected visual acuity (BCVA) improved significantly with mean postoperative BCVA of 0.7logMAR (6/30 Snellens equivalent) (P < 0.001). Anatomical closure rate of 72% was achieved (P < 0.001). CONCLUSION: Internal limiting membrane peel is associated with significant alteration in inner retinal architecture, especially in ganglion cell layer, which can adversely influence functional outcome of the surgery and makes it imperative to avoid peeling internal limiting membrane over a larger surface area.

COMPARATIVE ANALYSIS OF OUTCOMES WITH VARIABLE DIAMETER INTERNAL LIMITING MEMBRANE PEELING IN SURGERY FOR IDIOPATHIC MACULAR HOLE REPAIR.

PURPOSE: To analyse whether the size of internal limiting membrane peeling influences the outcome of macular hole surgery. METHODS: Prospective, comparative, interventional study. Fifty eyes were included. Twenty-five eyes had smaller (3-mm) peel (Group 1), whereas the other 25 had larger (5-mm) peel (Group 2). Outcome measures were macular hole closure rate, improvement in best corrected visual acuity, retinal nerve fiber layer, and ganglion cell layer thickness (0.5 mm, 1.5 mm, and 2.5 mm temporal and medial to the fovea), external limiting membrane, inner segment outer segment layer, and cone outer segment tip restoration. RESULTS: Both the groups were matched for demographic parameters, spectral-domain optical coherence tomography-based macular hole staging and dimensions. Hole closure rates were similar, 80% and 65% in Group 1 and 2, respectively (P = 0.20). No difference was observed in anatomical success rate, irrespective of size, stage, or duration of hole. Visual improvement was better in Group 1 (4 lines vs. 2-line Early Treatment Diabetic Retinopathy Study equivalent; P = 0.04); the retinal nerve fiber layer was thinner at all locations in Group 2, with the difference being significant, 2.5 mm temporal to the fovea (P < 0.05), whereas the ganglion cell layer was thicker in the 3-mm group, significantly so at the location, 1.5 mm temporal to the fovea (P = 0.01). Outer layer restoration rates were also similar in both the groups. CONCLUSION: Macular hole closure rate was similar in both the groups; however, smaller (3-mm) peel group demonstrated better functional improvement and nerve fiber layer preservation.

"VACUOLE" SIGN ADJACENT TO RETINAL PIGMENT EPITHELIAL DEFECTS ON SPECTRAL DOMAIN OPTICAL COHERENCE TOMOGRAPHY IN CENTRAL SEROUS CHORIORETINOPATHY ASSOCIATED WITH SUBRETINAL FIBRIN.

PURPOSE: To report spectral domain optical coherence tomography features in central serous chorioretinopathy associated with subretinal fibrin. METHOD: Retrospective observational case series of patients with central serous chorioretinopathy with subretinal fibrin imaged with spectral domain optical coherence tomography. RESULT: Twenty-three eyes of 23 patients (19 males and 4 females), with mean age of 39.09 ± 5.8 years were included in the study. Subretinal fibrin clinically ranged from localized well-defined areas to extensive ill-defined areas. Along with the presence of subretinal hyperreflectivity (n = 23, 100%), corresponding to fibrin, spectral domain optical coherence tomography also revealed the presence of the retinal pigment epithelial (RPE) defects (n = 23, 100%) in all eyes with an adjacent well-defined hyporeflective vacuole. In 19 eyes wherein fundus fluorescein was performed, the RPE defects and vacuoles corresponded to the site of RPE leak. Serous pigment epithelial detachments (n = 18, 78.2%), multiple RPE defects in the same eye (n = 5), and multiple RPE defects in same pigment epithelial detachment (n = 1) were few other interesting features observed. CONCLUSION: The presence of a hyporeflective vacuole amid the hyperreflective fibrin adjacent to RPE defects probably indicates the site of constant fluid egress and is an important sign of disease activity especially in cases where fundus fluorescein angiography is not possible.

CHARACTERIZATION OF MACULAR CHOROIDAL THICKNESS IN ISCHEMIC AND NONISCHEMIC DIABETIC MACULOPATHY.

PURPOSE: To evaluate changes in macular choroidal thickness in eyes with ischemic and nonischemic diabetic maculopathy. METHODS: Cross-sectional study of enhanced depth imaging optical coherence tomography of patients with diabetes. The diabetic eyes were divided into 3 groups: 1) eyes with no diabetic retinopathy (NDR); 2) those with diabetic retinopathy without macular ischemia (DR/MI-); and 3) those with diabetic retinopathy and macular ischemia (DR/MI+). RESULTS: This analysis included 261 eyes of 160 patients. Eighty-eight eyes belonged to the NDR, 90 to the DR/MI-, and 83 to the DR/MI+ group. The choroidal thickness was significantly reduced in the DR/MI+ group as compared with the other 2 groups in the subfoveal region (NDR: 285.94 ± 80.38 µm, DR/MI-: 311.22 ± 94.55 µm, DR/MI+: 216.06 ± 58.41 µm; P < 0.001), nasally and temporally (P < 0.01). Between the NDR and DR/MI- groups, the choroidal thickness was significantly reduced nasally (P = 0.02) in the NDR group, but not subfoveally (P = 0.1) and temporally (P = 0.2). Notably, no statistically significant difference in central macular thickness was found between the DR/MI- (328.68 ± 103.28 µm) and DR/MI+ (341.99 ± 130.63 µm) groups (P = 1), although it was found to significantly increase in both these groups as compared with the NDR group (264.03 ± 27.74 µm; P < 0.001). CONCLUSION: In diabetic maculopathy, an overall significant reduction was observed in macular choroidal thickness in eyes in ischemic stage as compared with nonischemic stage. In vivo evaluation of choroidal structural changes in the form of choroidal thickness may possibly be intuitive in understanding the pathogenesis of progression of diabetic maculopathy from nonischemic to ischemic stage, and associated functional damage.

Dosimetric impact of cylinder size in high-dose rate vaginal cuff brachytherapy (VCBT) for primary endometrial cancer.

The purpose of this study was to evaluate the dosimetric impact of cylinder size in high-dose-rate (HDR) vaginal cuff brachytherapy (VCBT). Sample plans of HDR VCBT in a list of cylinders ranging from 2.5 to 4 cm in diameter at 0.5 cm incre-ment were created and analyzed. The doses were prescribed either at the 0.5cm depth with 5.5 Gy for 4 fractions or at the cylinder surface with 8.8 Gy for 4 frac-tions, in various treatment lengths. A 0.5 cm shell volume called PTV_Eval was contoured for each plan and served as the target volume for dosimetric evaluation. The cumulative and differential dose volume histograms (c-DVH and d-DVH), mean doses (D-mean) and the doses covering 90% (D90), 10% (D10), and 5% (D5) of PTV_Eval were calculated. In the 0.5 cm depth regimen, the DVH curves were found to have shifted toward the lower dose zone when a larger cylinder was used, but in the surface regimen the DVH curves shifted toward the higher dose zone as the cylinder size increased. The D-means of the both regimens were between 6.9 and 7.8 Gy and dependent on the cylinder size but independent of the treatment length. A 0.5 cm variation of diameter could result in a 4% change of D-mean. Average D90s were 5.7 (ranging from 5.6 to 5.8 Gy) and 6.1 Gy (from 5.7 to 6.4 Gy), respectively, for the 0.5 cm and surface regimens. Average D10 and D5 were 9.2 and 11 Gy, respectively, for the 0.5 cm depth regimen, and 8.9 and 9.7 Gy, respectively, for the surface regimen. D-mean, D90, D10, and D5 for other prescription doses could be calculated from the lookup tables of this study. Results indicated that the cylinder size has moderate dosimetric impact, and that both regimens are comparable in dosimetric quality.

Progression of diabetic retinopathy following uncomplicated phacoemulsification: A prospective study from South India.

AIM: The aim of this study was to study the progression of diabetic retinopathy (DR) and macular edema in uncomplicated phacoemulsification in patients with diabetes mellitus with a follow-up of 6 months. METHODS: A prospective, nonrandomized study was conducted on patients with established or no DR in a known case of diabetes mellitus undergoing cataract surgery by phacoemulsification, with no intraoperative complications. Detailed ophthalmic evaluation including fundus examination was done in all cases, and DR staging was done. Optical coherence tomography and fundus fluorescein angiography were done in indicated cases. Fundus evaluation was done during the follow-up visits in 3 weeks, 3 months, and 6 months postsurgery and the tests were repeated if necessary. RESULTS: In the current study, there was a statistically significant improvement in best-corrected visual acuity after cataract surgery compared to the preoperative value. From the 330 eyes we analyzed, there was a progression of DR in only 18 eyes (5.45%) following phacoemulsification. There was a statistically significant increase in central macular thickness (CMT) at 3 weeks postoperative (433.82 ± 137.572) compared to that of the preoperative CMT (295.98 ± 97.959). From the 22 eyes which showed a progression of diabetic maculopathy, 11 eyes had developed new-onset macular edema following the cataract surgery, 11 eyes had progression of preexisting edema, and 4 of them had to undergo intravitreal anti-vascular endothelial growth factor injections as the treatment. CONCLUSION: The chance of progression of DR staging is low after uncomplicated phacoemulsification, on a short term. However, the chances of worsening of macular edema as well as worsening of proliferative stages should be kept in mind while advising a patient for cataract surgery.

Determination of thePrpand radial dose correction factor in reference dosimetry.

Objectives.In an addendum to AAPM TG-51 protocol, McEwenet al, (DOI:10.1118/1.4866223) introduced a new factorPrpto account for the radial dose distribution of the photon beam over the detector volume mainly in flattening filter free (FFF) beams.Prpand its extension to non-FFF beam reference dosimetry is investigated to see its impact in a clinical situation.Approches.ThePrpwas measured using simplified version of Sudhyadhomet al(DOI:10.1118/1.4941691) for Elekta and Varian FFF beams with two commonly used calibration detectors; PTW-30013 and Exradin-A12 ion chambers after acquiring high resolution profiles in detectors cardinal coordinates. For radial dose correction factor, the ion chambers were placed in a small water phantom and the central axis position was set to center of the sensitive volume on the treatment table and was studied by rotating the table by 15-degree interval from -90 to +90 degrees with respect to the initial (zero) position.Main results.The magnitude ofPrpvaries very little with machine, detector and beam energies to a value of 1.003 ± 0.0005 and 1.005 ± 0.0005 for 6FFF and 10FFF, respectively. The radial anisotropy for the Elekta machine with Exradin-A12 and PTW-30013 detector the magnitudes are in the range of (0.9995±0.0011 to 1.0015±0.0010) and (0.9998±0.0007 to 1.0015±0.0010), respectively. Similarly, for the Varian machine with Exradin-A12 and PTW-30013 ion chambers, the magnitudes are in the range of (1.0004±0.0010 to 1.0018±0.0018) and (1.0006±0.0009 to 1.0027±0.0007), respectively.Significance.ThePrpis ≤ 0.3% and 0.5% for 6FFF and 10FFF, respectively. The radial dose correction factor in regular beams also does not impact the dosimetry where the maximum magnitude is ±0.2% which is within experimental uncertainty.

Relevance of multicolor imaging, its component channels, and fundus autofluorescence in describing macular telangiectasia type-2 (MacTel) lesion characteristics.

PURPOSE: The aim of the study was to describe imaging characteristics and detection rates of phenotypic features in macular telangiectasia type-2 (MacTel) on multicolor (MC), blue reflectance (BR), green reflectance (GR), infrared reflectance (IR), and fundus autofluorescence (FAF) and to evaluate sensitivity, specificity, and predictive values across modalities. METHODS: In this monocentric observational study, 282 eyes of 148 patients with MacTel underwent color fundus photograph, MC, BR, GR, IR, FAF, spectral-domain optical coherence tomography (SD-OCT), OCT-angiography (OCT-A), and fundus fluorescein angiography (FFA). Grading was done by two graders qualitatively and quantitatively for the presence of the following prespecified MacTel findings [crystals, right-angle vessels (RAVs), plaques, subretinal neovascularization (SRNV), and MacTel area]. Across each imaging modality, the detection rate of RAVs and SRNV was compared with reference standard OCT-A (RAVs and SRNV) and FFA (SRNV), whereas that of plaques was compared with reference standard SD-OCT. RESULTS: MC identified overall MacTel characteristics in 92.7% of eyes. Regarding the presence, number, and quadrants of RAVs and the presence and number of crystals, MC and GR had superior detection rates as well as the highest sensitivity and negative predictive value. Retinal plaques were better detected using FAF (97%), followed by MC (88%). In proliferative MacTel, SRNV was identified in 86% and 79% of eyes on MC and IR, respectively. While BR clearly delineated MacTel area in 100% eyes, FAF was able to ascertain a larger area of involvement in proliferative MacTel. CONCLUSION: The findings demonstrate the ability of MC, its component channels, and FAF to describe MacTel characteristics qualitatively and quantitatively.

Determining risk and predictors of head and neck cancer treatment-related lymphedema: A clinicopathologic and dosimetric data mining approach using interpretable machine learning and ensemble feature selection.

Background and purpose: The ability to determine the risk and predictors of lymphedema is vital in improving the quality of life for head and neck (HN) cancer patients. However, selecting robust features is challenging due to the multicollinearity and high dimensionality of radiotherapy (RT) data. This study aims to overcome these challenges using an ensemble feature selection technique with machine learning (ML). Materials and methods: Thirty organs-at-risk, including bilateral cervical lymph node levels, were contoured, and dose-volume data were extracted from 76 HN treatment plans. Clinicopathologic data was collected. Ensemble feature selection was used to reduce the number of features. Using the reduced features as input to ML and competing risk models, internal and external lymphedema prediction capability was evaluated with the ML models, and time to lymphedema event and risk stratification were estimated using the risk models. Results: Two ML models, XGBoost and random forest, exhibited robust prediction performance. They achieved average F1-scores and AUCs of 84 ± 3.3 % and 79 ± 11.9 % (external lymphedema), and 64 ± 12 % and 78 ± 7.9 % (internal lymphedema). Predictive ML and risk models identified common predictors, including bulky node involvement, high dose to various lymph node levels, and lymph nodes removed during surgery. At 180 days, removing 0-25, 26-50, and > 50 lymph nodes increased external lymphedema risk to 72.1 %, 95.6 %, and 57.7 % respectively (p = 0.01). Conclusion: Our approach, involving the reduction of HN RT data dimensionality, resulted in effective ML models for HN lymphedema prediction. Predictive dosimetric features emerged from both predictive and competing risk models. Consistency with clinicopathologic features from other studies supports our methodology.

Clinical, Pathologic, and Dosimetric Predictors of Head and Neck Lymphedema Following Definitive or Adjuvant Radiation Therapy for Head and Neck Cancer.

Purpose: Head and neck lymphedema (HNL) following radiation therapy for head and neck cancer (HNC) causes patient morbidity. Predicting individual patients' risk of HNL after treatment is challenging. We aimed to identify the demographic, disease-related, and treatment-related factors associated with external and internal HNL following treatment of HNC with definitive or adjuvant radiation therapy. Methods and Materials: Relevant clinical, pathologic, and dosimetric data for 76 consecutive patients who received definitive or adjuvant radiation ± chemotherapy were retrospectively collected from a single institution. Multivariable models predictive of external and internal lymphedema using clinicopathologic variables alone and in combination with dosimetric variables were constructed and optimized using competing risk regression. Results: After median follow-up of 550 days, the incidence of external and internal HNL at 360 days was 70% and 34%, respectively. When evaluating clinical and treatment-related factors alone, number of lymph nodes removed and advanced adenopathy status were predictive of external lymphedema. With incorporation of dosimetric variables, the optimized model included the percentage volume of the contralateral lymph node level VII receiving 30Gy V30 ≥50%, number of lymph nodes removed, and advanced adenopathy status. For internal lymphedema, our clinicopathologic model identified both adjuvant radiation, as opposed to definitive radiation, and advanced adenopathy status. With inclusion of a dosimetric variable, the optimized model included larynx V45 ≥50% and advanced adenopathy. Conclusions: HNL following HNC treatment is common. For both external and internal lymphedema, nodal disease burden at diagnosis predicts increased risk. For external lymphedema, increasing extent of lymph node dissection prior to adjuvant therapy increases risk. The contralateral level VII lymph node region is also predictive of external lymphedema when radiation dose to V30 is ≥50%, meriting investigation. For internal lymphedema, we confirm that increasing radiation dose to the larynx is the most significant dosimetric predictor of mucosal edema when larynx V45 is ≥50%.

Brolucizumab-associated intraocular inflammation in Indian patients by VRSI study group.

CONTEXT: Concerns about brolucizumab's (Pagenax®) association with intraocular inflammation (IOI) limit its use despite its cost-effectiveness and efficacy. This multicentric study analyzes IOI incidence across 21 tertiary eyecare centers in India since its introduction in October 2020. PURPOSE: To determine the real-world incidence rate of IOI in Indian patients secondary to intravitreal brolucizumab across 21 tertiary eye care centers in India. SETTINGS AND DESIGN: Retrospective multicentric, survey-based study. METHODS: Data including number of patients treated, clinical indications, side effects encountered, and IOI case details was collected via Google Forms in 21 Indian tertiary eye care centers since October 2020. Mean, median, frequency, and standard deviation were calculated for statistical analysis. RESULTS: All centers used pro re nata protocol for brolucizumab injections with a minimum injection interval of 8 weeks. The incidence of IOI was 0.79% (21 events out of 2655 eyes). Treatment indications included idiopathic polypoidal choroidal vasculopathy, neovascular age-related macular degeneration, diabetic macular edema, and off-label uses. IOI was experienced after the first injection (57%) in majority of cases with a median onset of 14 days (range: 1-65 days). IOI was mild in 28.5%, moderate in 33%, and severe in 38% of cases. Eighteen out of 21 IOI eyes recovered preinjection best corrected visual acuity or better. CONCLUSIONS: Our study found a lower IOI incidence (0.79%) with brolucizumab (Pagenax) in Indian patients compared to previously reported literature. IOI events were mostly mild to moderate, and post-treatment, most patients improved or maintained BCVA. Larger prospective multicentric studies with PRN dosing protocol are needed to confirm these findings.