Apparent diffusion coefficient values predict response to brachytherapy in bulky cervical cancer.

BACKGROUND: Diffusion-weighted magnetic resonance imaging (DWI) provides a measurement of tumor cellularity. We evaluated the potential of apparent diffusion coefficient (ADC) values obtained from post-external beam radiation therapy (EBRT) DWI and prior to brachytherapy (BT) to predict for complete metabolic response (CMR) in bulky cervical cancer. METHODS: Clinical and DWI (b value = 500 s/mm2) data were obtained from patients undergoing interstitial BT with high-risk clinical target volumes (HR-CTVs) > 30 cc. Volumes were contoured on co-registered T2 weighted images and 90th percentile ADC values were calculated. Patients were stratified by CMR (defined by PET-CT at three months post-BT). Relation of CMR with 90th percentile ADC values and other clinical factors (International Federation of Gynecology and Obstetrics (FIGO) stage, histology, tumor and HR-CTV size, pre-treatment hemoglobin, and age) was assessed both in univariate and multivariate logistic regression analyses. Youden's J statistic was used to identify a threshold value. RESULTS: Among 45 patients, twenty-eight (62%) achieved a CMR. On univariate analysis for CMR, only 90th percentile ADC value was significant (p = 0.029) while other imaging and clinical factors were not. Borderline significant factors were HR-CTV size (p = 0.054) and number of chemotherapy cycles (p = 0.078). On multivariate analysis 90th percentile ADC (p < 0.0001) and HR-CTV size (p < 0.003) were highly significant. Patients with 90th percentile ADC values above 2.10 × 10- 3 mm2/s were 5.33 (95% CI, 1.35-24.4) times more likely to achieve CMR. CONCLUSIONS: Clinical DWI may serve to risk-stratify patients undergoing interstitial BT for bulky cervical cancer.

Timely delivery of PORT for head and neck squamous cell carcinoma in a county hospital.

Objectives: The objective of this study was to compare the rate of post-operative radiation therapy (PORT) initiation within 6 weeks for head and neck squamous cell carcinoma patients treated at a safety net, academic institutio between 2019 and 2021 versus those treated in 2022 after implementation of a new clinical pathway. Methods: A retrospective case-control study was performed at a single tertiary care, safety-net, academic institution. Patient demographics, tumor characteristics, dates of surgery, and other treatment dates were collected from the electronic medical record. The time from surgery to PORT was calculated. Patients who started radiation treatment within 42 days of surgery were regarded as having started PORT on time. The demographics, tumor characteristics, and rate of timely PORT for the two cohorts of patients were compared. Results: From 2018 to 2021, our rate of PORT initiation within 6 weeks of surgery was 12% (n = 57). In 2022, our rate of timely PORT was 88% (n = 16), p < 0.5. Patient demographics and characteristics were similar with the exception of marital status and use of free-flap reconstruction. The 2022 cohort was more likely to be single (p < 0.5), and all patients underwent free-flap reconstruction in 2022 (p < 0.05). Conclusion: Early referrals, frequent communication, and use of a secure registry were the key to the success found by our group despite the socioeconomic challenges of our underserved, safety-net hospital patient population. The changes made at our institution should serve as a template for other institutions seeking to improve the quality of care for their HNSCC patients.

Uncertainty in magnetic resonance imaging-based prostate postimplant dosimetry: Results of a 10-person human observer study, and comparisons with automatic postimplant dosimetry.

PURPOSE: Uncertainties in postimplant quality assessment (QA) for low-dose-rate prostate brachytherapy (LDRPBT) are introduced at two steps: seed localization and contouring. We quantified how interobserver variability (IoV) introduced in both steps impacts dose-volume-histogram (DVH) parameters for MRI-based LDRPBT, and compared it with automatically derived DVH parameters. METHODS AND MATERIALS: Twenty-five patients received MRI-based LDRPBT. Seven clinical observers contoured the prostate and four organs at risk, and 4 dosimetrists performed seed localization, on each MRI. Twenty-eight unique manual postimplant QAs were created for each patient from unique observer pairs. Reference QA and automatic QA were also performed for each patient. IoV of prostate, rectum, and external urinary sphincter (EUS) DVH parameters owing to seed localization and contouring was quantified with coefficients of variation. Automatically derived DVH parameters were compared with those of the reference plans. RESULTS: Coefficients of variation (CoVs) owing to contouring variability (CoVcontours) were significantly higher than those due to seed localization variability (CoVseeds) (median CoVcontours vs. median CoVseeds: prostate D90-15.12% vs. 0.65%, p < 0.001; prostate V100-5.36% vs. 0.37%, p < 0.001; rectum V100-79.23% vs. 8.69%, p < 0.001; EUS V200-107.74% vs. 21.18%, p < 0.001). CoVcontours were lower when the contouring observers were restricted to the 3 radiation oncologists, but were still markedly higher than CoVseeds. Median differences in prostate D90, prostate V100, rectum V100, and EUS V200 between automatically computed and reference dosimetry parameters were 3.16%, 1.63%, -0.00 mL, and -0.00 mL, respectively. CONCLUSIONS: Seed localization introduces substantially less variability in postimplant QA than does contouring for MRI-based LDRPBT. While automatic seed localization may potentially help improve workflow efficiency, it has limited potential for improving the consistency and quality of postimplant dosimetry.

A 3D-Printable, Low-Cost Obturator for Less Invasive Gynecologic Brachytherapy.

The purpose of this report is to design, develop, and evaluate a cost-effective applicator for interstitial brachytherapy (ISBT) to minimize patient morbidity and facilitate access to curative radiation treatment for gynecologic cancers, especially in low-resource settings. A computer-aided design and prototype were developed of a proposed applicator that incorporates 44 slotted channels to gently guide needles, with or without a tandem, through the vaginal canal, effectively eliminating the need for transcutaneous needle insertions typically employed during ISBT of advanced gynecologic cancer and thus reducing the risk of vaginal laceration and bladder or rectal injury. The tested prototype was developed using AutoCAD software (Autodesk, San Francisco, CA) and 3D printed in Accura Xtreme Gray material using stereolithography. Small-scale iterative tests using a gelatin phantom were conducted on this prototype to confirm the efficacy of the applicator through inter-operator usability, needle stability, and needle arrangement. A promising prototype was developed aimed at addressing key issues with traditional perineum-based templates to facilitate ISBT, including being able to cover bulky tumors with parametrial extension reliably, decrease the risk of tissue or organ injury, and treat women with a prior hysterectomy. Results of preclinical testing demonstrated that the applicator met its purpose, suggesting that it may facilitate ISBT without the morbidity typically associated with the procedure, especially by addressing concerns associated with implementing the procedure in low-resource settings. The applicator shows substantial promise in the treatment of advanced gynecologic cancer. While further testing remains necessary to confirm its translatability to the clinical setting, the applicator appears capable of meeting its design objectives, representing its potential for improving upon current methods.

High risk lung nodule: A multidisciplinary approach to diagnosis and management.

Pulmonary nodules are often discovered incidentally during CT scans performed for other reasons. While the vast majority of nodules are benign, a small percentage may represent early-stage lung cancer with the potential for curative treatments. With the growing use of CT for both clinical purposes and lung cancer screening, the number of pulmonary nodules detected is expected to increase substantially. Despite well-established guidelines, many nodules do not receive proper evaluation due to a variety of factors, including inadequate coordination of care and financial and social barriers. To address this quality gap, novel approaches such as multidisciplinary nodule clinics and multidisciplinary boards may be necessary. As pulmonary nodules may indicate early-stage lung cancer, it is crucial to adopt a risk-stratified approach to identify potential lung cancers at an early stage, while minimizing the risk of harm and expense associated with over investigation of low-risk nodules. This article, authored by multiple specialists involved in nodule management, delves into the diagnostic approach to lung nodules. It covers the process of determining whether a patient requires tissue sampling or continued surveillance. Additionally, the article provides an in-depth examination of the various biopsy and therapeutic options available for malignant lung nodules. The article also emphasizes the significance of early detection in reducing lung cancer mortality, especially among high-risk populations. Furthermore, it addresses the creation of a comprehensive lung nodule program, which involves smoking cessation, lung cancer screening, and systematic evaluation and follow-up of both incidental and screen-detected nodules.

Three-dimensional (3D) anatomic location, extension, and timing of severe osteoradionecrosis of the mandible.

Background: The purpose of this study was to describe the topography, extension (volume), and timing of severe osteoradionecrosis (ORN) that required mandible resection in patients previously treated for head and neck cancer at a high-volume Veterans Affairs Medical Center. Materials and methods: The records from a reference hyperbaric oxygen clinic were retrospectively analyzed (n = 50, 2018-2021). Inclusion criteria were: I) severe ORN defined as progressive ORN that required resection; II) pathologic confirmation of ORN; and III) availability of pre-operative CT-imaging. Using a radiotherapy (RT) imaging software, we performed a detailed volumetric (3D) analysis of the bone involvement by ORN. Time intervals from RT to surgery for ORN and from surgery to the last follow-up were calculated. Results: All patients that met inclusion criteria (n = 10) were male with significant smoking history (median 47.5 pack-years) and a median age of 57 years old at the time of RT. The primary tumors were: oropharynx (n = 6), oral cavity (n = 3) and nasopharynx (n = 1). The median time from RT to ORN surgery was 8 years. The most common ORN location was the posterior lateral body (molar) and six patients had associated fractures. The mean ORN volume was 3.6 cc (range: 0.6-8.3), corresponding to a mean 6.3% (range: 0.7-14) of the total mandibular volume. After a median follow-up of 13.5 months, no recurrence of ORN occurred. Three patients died of non-cancer and non-ORN-recurrence related causes (1 y OS 77.1%). Conclusion: Severe ORN occurred after a median of 8 years from the previous RT and usually affected the posterior lateral body. Surgical resection achieved excellent ORN control.

Implementation of High-Dose-Rate, CT-Based Prostate Brachytherapy in an Academic Teaching Hospital and Residency Training Program.

Introduction Prostate brachytherapy provides the most durable local control for prostate adenocarcinoma among all radiation treatment options. However, likely due to decreased trainee familiarity with the technique and resource intensity, it has seen a decline in utilization. Here we outline our experience with starting a high-dose-rate (HDR) prostate brachytherapy program within a residency training program and present our outcome data. Methods Patients were identified and screened using clinical data and volume study for candidacy for brachytherapy implantation. Eligible candidates were implanted and subsequently had radiation planning and delivery in our clinic. Descriptive statistical analysis was performed on our outcomes and dosimetry data and presented in tabular form. Results Seventeen patients were treated for a total of 18 implants (one monotherapy). No implant was aborted. No acute urinary retention requiring catheterization or chronic urethral stricture occurred. Biochemical recurrence-free survival was 94% at a median follow-up of 28.5 months (range 8.2-50 months); the one failure occurred in a very high-risk patient at 37 months following treatment. Dosimetrically, prostate coverage, urethra sparing, and rectum sparing aims were met. Volumetric bladder aims were also met; however, the max point dose to the bladder neck was above the guideline. Conclusion Our department successfully implemented an HDR prostate brachytherapy program. Treatments were effective and there was no grade 3 toxicity to report.

Computer-aided segmentation on MRI for prostate radiotherapy, part II: Comparing human and computer observer populations and the influence of annotator variability on algorithm variability.

BACKGROUND AND PURPOSE: Comparing deep learning (DL) algorithms to human interobserver variability, one of the largest sources of noise in human-performed annotations, is necessary to inform the clinical application, use, and quality assurance of DL for prostate radiotherapy. MATERIALS AND METHODS: One hundred fourteen DL algorithms were developed on 295 prostate MRIs to segment the prostate, external urinary sphincter (EUS), seminal vesicles (SV), rectum, and bladder. Fifty prostate MRIs of 25 patients undergoing MRI-based low-dose-rate prostate brachytherapy were acquired as an independent test set. Groups of DL algorithms were created based on the loss functions used to train them, and the spatial entropy (SE) of their predictions on the 50 test MRIs was computed. Five human observers contoured the 50 test MRIs, and SE maps of their contours were compared with those of the groups of the DL algorithms. Additionally, similarity metrics were computed between DL algorithm predictions and consensus annotations of the 5 human observers' contours of the 50 test MRIs. RESULTS: A DL algorithm yielded statistically significantly higher similarity metrics for the prostate than did the human observers (H) (prostate Matthew's correlation coefficient, DL vs. H: planning-0.931 vs. 0.903, p < 0.001; postimplant-0.925 vs. 0.892, p < 0.001); the same was true for the 4 organs at risk. The SE maps revealed that the DL algorithms and human annotators were most variable in similar anatomical regions: the prostate-EUS, prostate-SV, prostate-rectum, and prostate-bladder junctions. CONCLUSIONS: Annotation quality is an important consideration when developing, evaluating, and using DL algorithms clinically.

Computer-aided segmentation on MRI for prostate radiotherapy, Part I: Quantifying human interobserver variability of the prostate and organs at risk and its impact on radiation dosimetry.

BACKGROUND AND PURPOSE: Quantifying the interobserver variability (IoV) of prostate and periprostatic anatomy delineation on prostate MRI is necessary to inform its use for treatment planning, treatment delivery, and treatment quality assessment. MATERIALS AND METHODS: Twenty five prostate cancer patients underwent MRI-based low-dose-rate prostate brachytherapy (LDRPBT). The patients were scanned with a 3D T2-weighted sequence for treatment planning and a 3D T2/T1-weighted sequence for quality assessment. Seven observers involved with the LDRPBT workflow delineated the prostate, external urinary sphincter (EUS), seminal vesicles, rectum, and bladder on all 50 MRIs. IoV was assessed by measuring contour similarity metrics, differences in organ volumes, and differences in dosimetry parameters between unique observer pairs. Measurements from a group of 3 radiation oncologists (G1) were compared against those from a group consisting of the other 4 clinical observers (G2). RESULTS: IoV of the prostate was lower for G1 than G2 (Matthew's correlation coefficient [MCC], G1 vs. G2: planning-0.906 vs. 0.870, p < 0.001; postimplant-0.899 vs. 0.861, p < 0.001). IoV of the EUS was highest of all the organs for both groups, but was lower for G1 (MCC, G1 vs. G2: planning-0.659 vs. 0.402, p < 0.001; postimplant-0.684 vs. 0.398, p < 0.001). Large differences in prostate dosimetry parameters were observed (G1 maximum absolute prostate ΔD90: planning-76.223 Gy, postimplant-36.545 Gy; G1 maximum absolute prostate ΔV100: planning-13.927%, postimplant-8.860%). CONCLUSIONS: While MRI is optimal in the management of prostate cancer with radiation therapy, significant interobserver variability of the prostate and external urinary sphincter still exist.

Proton Therapy for Major Salivary Gland Cancer: Clinical Outcomes.

PURPOSE: To report clinical outcomes in terms of disease control and toxicity in patients with major salivary gland cancers (SGCs) treated with proton beam therapy. MATERIALS AND METHODS: Clinical and dosimetric characteristics of patients with SGCs treated from August 2011 to February 2020 on an observational, prospective, single-institution protocol were abstracted. Local control and overall survival were calculated by the Kaplan-Meier method. During radiation, weekly assessments of toxicity were obtained, and for patients with ≥ 90 days of follow-up, late toxicity was assessed. RESULTS: Seventy-two patients were identified. Median age was 54 years (range, 23-87 years). Sixty-three patients (88%) received postoperative therapy, and nine patients (12%) were treated definitively. Twenty-six patients (36%) received concurrent chemotherapy. Nine patients (12%) had received prior radiation. All (99%) but one patient received unilateral treatment with a median dose of 64 GyRBE (relative biological effectiveness) (interquartile range [IQR], 60-66), and 53 patients (74%) received intensity-modulated proton therapy with either single-field or multifield optimization. The median follow-up time was 30 months. Two-year local control and overall survival rates were 96% (95% confidence interval [CI] 85%-99%) and 89% (95% CI 76%-95%], respectively. Radiation dermatitis was the predominant grade-3 toxicity (seen in 21% [n = 15] of the patients), and grade ≥ 2 mucositis was rare (14%; n = 10 patients). No late-grade ≥ 3 toxicities were reported. CONCLUSION: Proton beam therapy for treatment of major SGCs manifests in low rates of acute mucosal toxicity. In addition, the current data suggest a high rate of local control and minimal late toxicity.

Early radiotherapy preserves vision in sporadic optic pathway glioma.

BACKGROUND: Sporadic optic pathway/hypothalamic gliomas represent a unique entity within pediatric low-grade glioma. Despite favorable survival, location makes treatment difficult and local progression debilitating. This study is a longitudinal assessment of visual acuity (VA) among children treated within the last 2 decades. METHODS: Clinical characteristics were abstracted for patients treated from 2000 to 2018 at Texas Children's Cancer Center in Houston. Ophthalmologic data taken at 3- to 6-month intervals were examined with age-appropriate VA metrics converted to the LogMAR (logarithm of the minimum angle of resolution) scale. Kaplan-Meier blindness-free survival (BFS) curves, calculated as time-to-bilateral functional blindness (LogMAR ≥0.8 in both eyes), were calculated for patients receiving early radiation therapy (RT; upfront or as first-line salvage treatment) or chemotherapy (CT) and evaluated using the log-rank test. RESULTS: Thirty-eight patients with a median follow-up of 8.5 years (range, 2-17 years) were identified. Median age at diagnosis was 3 years (interquartile range, <1-6 years). Early RT was administered in 11 patients (29%). Twenty-seven patients (71%) were treated primarily with CT, initiated at a median age of 3.5 years (range, <1-11 years). Eight patients in the CT group did eventually require RT secondary to VA loss and following multiple lines of CT. Median age at RT for all patients was 11 years (range, 3-17 years). BFS rates were 81% at 5 years and 60% at 8 years for CT and 100% at 5 and 8 years for early RT (P = .017). CONCLUSIONS: In a contemporary cohort, early RT, defined as initial or first-line salvage therapy, was found to have superior BFS for appropriately selected patients with sporadic optic pathway/hypothalamic gliomas. LAY SUMMARY: Children with low-grade brain tumors of the optic pathway generally have excellent long-term survival; however, given the location of these tumors, there can commonly be threatened vision if the tumor grows. Although radiation is generally deferred in children on the basis of legitimate concerns regarding the effects on the developing brain, it may represent a vision-preserving therapy for well-selected older patients.

Scoliosis in Children Treated With Photon Craniospinal Irradiation for Medulloblastoma.

PURPOSE: Scoliosis is a well-recognized complication after abdominal radiation therapy but not reported frequently after craniospinal irradiation (CSI). We examined the incidence and risk factors for scoliosis after CSI in long-term survivors with medulloblastoma. METHODS AND MATERIALS: The records of patients with medulloblastoma seen at one institution from 1996 to 2006 were analyzed for the use of CSI and development of scoliosis as documented on physical examination and spinal imaging. RESULTS: We identified 35 children with medulloblastoma who were ≤12 years of age at time of CSI with a median 14.3 years (range, 5.8-19.3 years) of follow-up. Twenty-seven (77.1%) were male, and median age at CSI was 6.8 years (range, 2.8-12 years). The cumulative incidence of scoliosis at 15 years was 34.6%. The median time to develop scoliosis was 7.1 years (range, 5-11.7 years) after CSI. Treatment with high dose CSI (34.2-40 Gy) and presence of hemiplegia or hemiparesis were found to be risk factors for development of scoliosis. CONCLUSIONS: Scoliosis is an underreported complication of photon craniospinal irradiation.

Paracervical blocks facilitate timely brachytherapy amidst COVID-19.

PURPOSE: The COVID-19 pandemic presents serious challenges for brachytherapists, and in the time-sensitive case of locally advanced cervical cancer, the need for curative brachytherapy (BT) is critical for survival. Given the high-volume of locally advanced cervical cancer in our safety-net hospital, we developed a strategy in close collaboration with our gynecology oncology and anesthesia colleagues to allow for completely clinic-based intracavitary brachytherapy (ICBT). METHODS AND MATERIALS: This technical report will highlight our experience with the use of paracervical blocks (PCBs) and oral multimodal analgesia (MMA) for appropriately selected cervical ICBT cases, allowing for completely clinic-based treatment. RESULTS: 18 of 19 (95%) screened patients were eligible for in-clinic ICBT. The excluded patient had significant vaginal fibrosis. 38 of 39 intracavitary implants were successfully transitioned for entirely in-clinic treatment utilizing PCBs and oral MMA (97% success rate). One case was aborted due to inadequate analgesia secondary to a significantly delayed case start time (PO medication effect diminished). 95% of patients reported no pain at the conclusion of the procedure. The median (IQR) D2cc for rectum and bladder were 64.8 (58.6-70.2) Gy and 84.1 (70.9-89.4) Gy, respectively. Median (IQR) CTV high-risk D90 was 88.0 (85.6-89.8) Gy. CONCLUSIONS: In a multidisciplinary effort, we have successfully transitioned many ICBT cases to the clinic with the use of PCB local anesthesia and oral multimodality therapy in direct response to the current pandemic, thereby mitigating exposure risk to patients and staff as well as reducing overall health care burden.

Prevalence of Musculoskeletal Work-related Injuries Among Radiation Therapists.

PURPOSE: To evaluate the prevalence of and risk factors associated with work-related musculoskeletal injuries among radiation therapists in the United States. METHODS: Approximately 16 000 radiation therapists were identified and electronically mailed a modified Nordic Musculoskeletal Questionnaire. For inclusion in the analysis, participants were required to be actively employed during the preceding 12-month period and hold a current position as a radiation therapist. Descriptive statistics, univariate and multivariate analyses, and text analysis were performed to assess personal and work-related factors that correlated with injury risk. RESULTS: Contact was established with 5827 radiation therapists (contact rate, 37%). Of these, 2747 responded (cooperation rate, 47%), of which 1867 met inclusion criteria. Prevalence of work-related musculoskeletal injuries at 12 months was 76%, with the most common site-specific injury in the lumbar back (20%), followed by the neck (17%) and shoulders (15%). An incident rate of 33 injuries per 100 full-time equivalents per year was calculated. Multiple logistic regression analyses revealed the following variables to be significantly associated with increased injury risk: female sex, a body mass index of 30 or greater, and tobacco use. Daily exercise was associated with decreased risk. Patient transfers, body mechanics, and heavy lifting were the primary reported sources of injuries. DISCUSSION: Radiation therapists appear to be at considerable risk for work-related musculoskeletal injuries, which corresponds with findings of studies on health care employees. The high prevalence observed among radiation therapists (76%) is similarly high among nurses, and the increased risk for women also has been reported among physical therapists. Furthermore, other study results support obesity and tobacco use as risk factors and daily exercise as decreasing risk. In this study, most radiation therapists indicated interest in safety training courses, which could be addressed by involving national programs and competency requirements. CONCLUSION: Further study is needed to address modifiable risk factors and implement interventions that reduce the high prevalence of work-related musculoskeletal injuries among radiation therapists. The results of such research might help decrease personal, societal, and radiation oncology practice-specific costs.

Dose-Escalated Radiation Therapy for Pancreatic Cancer: A Simultaneous Integrated Boost Approach.

PURPOSE: To provide a detailed description of practical approaches to dose escalation in pancreatic cancer. METHODS AND MATERIALS: The current paper represents an international collaborative effort of radiation oncologists from the MR-linac consortium with expertise in pancreatic dose escalation. RESULTS: A 15-fraction hypofractionated intensity modulated radiation therapy (67.5 Gy in 15 fractions) and 5-fraction stereotactic body radiation therapy case (50 Gy in 5 fractions) are presented with information regarding patient selection, target volumes, organs at risk, dose constraints, and specific considerations regarding quality assurance. Additionally, we address barriers to dose escalation and briefly discuss future directions in dose escalation for pancreatic cancer, including particle therapy and magnetic resonance guided radiation therapy. CONCLUSIONS: This article on dose escalation for pancreatic cancer may help to guide academic and community based physicians and to serve as a reference for future therapeutic trials.

MRI-assisted radiosurgery: A quality assurance nomogram for palladium-103 and iodine-125 prostate brachytherapy.

PURPOSE: We sought to develop an activity nomogram for magnetic resonance (MR)-planned permanent seed prostate brachytherapy to improve quality assurance through a secondary dosimetric check. METHODS AND MATERIALS: Patients undergoing MRI-assisted radiosurgery (MARS), whereby MRI is used for preoperative planning and postimplant dosimetry, were reviewed from May 2016 to September 2018. Planned activity (U) was fitted by MR-prostate volume (cc) via simple linear regression. Resulting monotherapy nomograms were compared with institutional nomograms from an ultrasound-planned cohort. Dosimetric coverage and external urinary sphincter (EUS) dose were also assessed for MR-planned patients. RESULTS: We identified 183 patients treated with MARS: 146 patients received palladium-103 (103Pd; 102 monotherapy and 44 boost), and 37 received iodine-125 (125I) monotherapy. Median prostate volume was 28 cc (interquartile range: 22-35). Lines of best fit for implant activity were U = 4.344 × (vol) + 54.13 (R2: 95%) for 103Pd monotherapy, U = 3.202 (vol) + 39.72 (R2: 96%) for 103Pd boost and U = 0.684 (vol) + 13.38 (R2: 96%) for 125I monotherapy. Compared with ultrasound, MR-planned nomograms had lower activity per volume (p < 0.05) for both 103Pd monotherapy (∼6%) and 125I monotherapy (∼11%), given a median size (30 cc) prostate. Across all MARS implants, postimplant dosimetry revealed a median V100% of 94% (interquartile range: 92-96%). Median EUS V125 was <1 cc for all patients, regardless of isotope. CONCLUSIONS: We developed a quality assurance nomogram for MR-planned prostate brachytherapy. When compared with ultrasound-planned, MR-planned monotherapy resulted in a lower activity-to-volume ratio while maintaining dosimetric coverage, likely secondary to EUS-sparing and reduced planning target margins.

Radiation-Induced Lung Injury: Assessment and Management.

Radiation-induced lung injury (RILI) encompasses any lung toxicity induced by radiation therapy (RT) and manifests acutely as radiation pneumonitis and chronically as radiation pulmonary fibrosis. Because most patients with thoracic and breast malignancies are expected to undergo RT in their lifetime, many with curative intent, the population at risk is significant. Furthermore, indications for thoracic RT are expanding given the advent of stereotactic body radiation therapy (SBRT) or stereotactic ablative radiotherapy (SABR) for early-stage lung cancer in nonsurgical candidates as well as oligometastatic pulmonary disease from any solid tumor. Fortunately, the incidence of serious pulmonary complications from RT has decreased secondary to advances in radiation delivery techniques. Understanding the temporal relationship between RT and injury as well as the patient, disease, and radiation factors that help distinguish RILI from other etiologies is necessary to prevent misdiagnosis. Although treatment of acute pneumonitis is dependent on clinical severity and typically responds completely to corticosteroids, accurately diagnosing and identifying patients who may progress to fibrosis is challenging. Current research advances include high-precision radiation techniques, an improved understanding of the molecular basis of RILI, the development of small and large animal models, and the identification of candidate drugs for prevention and treatment.