During an ultrasound (US) scan, the sonographer is in close contact with the patient, which puts them at risk of COVID-19 transmission. In this paper, we propose a robot-assisted system that ...automatically scans tissue, increasing sonographer/patient distance and decreasing contact duration between them. This method is developed as a quick response to the COVID-19 pandemic. It considers the preferences of the sonographers in terms of how US scanning is done and can be trained quickly for different applications. Our proposed system automatically scans the tissue using a dexterous robot arm that holds US probe. The system assesses the quality of the acquired US images in real-time. This US image feedback will be used to automatically adjust the US probe contact force based on the quality of the image frame. The quality assessment algorithm is based on three US image features: correlation, compression and noise characteristics. These US image features are input to the SVM classifier, and the robot arm will adjust the US scanning force based on the SVM output. The proposed system enables the sonographer to maintain a distance from the patient because the sonographer does not have to be holding the probe and pressing against the patient's body for any prolonged time. The SVM was trained using bovine and porcine biological tissue, the system was then tested experimentally on plastisol phantom tissue. The result of the experiments shows us that our proposed quality assessment algorithm successfully maintains US image quality and is fast enough for use in a robotic control loop.
PurposeThis study investigated reliable vaginal mucosa dose-volume histogram (DVH) metrics in gynecologic template interstitial high-dose-rate brachytherapy (HDR-BT) for the purpose of standardized ...dose reporting.Material and methodsGynecologic template (Syed/Neblett) interstitial HDR-BT patients treated from September 2016 to November 2022 at the study institute were included in the cohort. Each patient implant included a vaginal mucosa contour defined by a 5 mm expansion from vaginal cylinder, then another volume with clinical target volume subtracted. DVH metrics were investigated between D0.1cc to D4cc. Clinical plans were re-calculated using Monte Carlo (MC) simulations both in heterogeneous material and in water.ResultsThe patient cohort included 61 patients with clinical plans using conventional homogeneous dose calculation (TG43). Heterogeneous vs. water MC dose differences were between -1.1% and -1.4% for all metrics investigated. DVH metrics D1cc and smaller resulted in > 5% discrepancies between TG43 and MC dose (to water) calculation due to the proximity of source positions in/nearby the vaginal mucosa. Reliability improved when DVH metric volume was larger (D2cc and D4cc). Both D2cc and D4cc presented very high linear correlation between TG43 and MC reported doses for the vagina, and average ± standard deviation dose difference was 4.6 ±2.9% and -3.0 ±1.9%, respectively. Dose differences decreased when the clinical target volume was removed: -1.5 ±3.5% and -0.8 ±2.1% for D2cc and D4cc, respectively.ConclusionsFor perineal template gynecologic HDR-BT procedures, the 2 cc volume is the smallest representative volume that reliably reports vaginal dose and at minimum should be reported to establish dose and outcome evaluation.
Purpose
The objective of this work is to outline a framework for dosimetric characterization that will comprehensively detail the clinical commissioning steps for 3D‐printed materials applied as ...patient support or immobilization devices in photon radiotherapy. The complex nature of 3D‐printed materials with application to patient‐specific configurations requires careful consideration. The framework presented is generalizable to any 3D‐printed object where the infill and shell combinations are unknown.
Methods
A representative cylinder and wedge were used as test objects to characterize devices that may be printed of unknown, patient‐specific dimensions. A case study of a 3D‐printed CSI immobilization board was presented as an example of an object of known, but adaptable dimensions and proprietary material composition. A series of measurements were performed to characterize the material's kV radiologic properties, MV attenuation measurements and calculations, energy spectrum water equivalency, and surface dose measurements. These measurements complement the recommendations of the AAPM's TG176 to characterize the additional complexity of 3D‐printed materials for use in a clinical radiotherapy environment.
Results
The dosimetric characterization of 3D‐printed test objects and a case study device informed the development of a step‐by‐step template that can easily be followed by clinicians to accurately and safely utilize 3D‐printed materials as patient‐specific support or immobilization devices.
Conclusions
A series of steps is outlined to provide a formulaic approach to clinically commission 3D‐printed materials that may possess varying material composition, infill patterns, and patient‐specific dimensions.
Post-implant analysis in permanent breast seed implant (PBSI) brachytherapy is an important component of the quality assurance process that indicates dosimetric quality relevant to patient outcome, ...indicating salvage therapy if inadequate, as well as providing feedback to the brachytherapy team to improve future treatments. To measure geometric indices on implant quality, plan reconstruction must be performed to correlate each planned and post-implant seed location. In this work, a simulated-annealing-based algorithm is developed to perform this plan reconstruction automatically.
The plan reconstruction algorithm was developed in MATLAB, taking the patient pre-treatment and post-implant (Day 0) plan and associated contours as inputs. For 19 treated patients, a reconstruction was obtained that defined the correspondence between each planned and post-implant seed. The simulated-annealing algorithm was used to reconstruct each patient 10 times to assess the variability in convergence. Manual reconstructions performed by at least two independent observers to obtain consensus were defined as the ground truth; these were compared to the automatic reconstructions obtained by the algorithm. Metrics on seed placement accuracy and needle strand angulation were calculated for the patients.
The algorithm performed reconstructions on 19 patients (1235 seeds) with ground-truth reconstructions, obtaining 97 ± 8% correct matches. This strong performance indicates the ability to incorporate this algorithm into the clinical quality assurance workflow.
The plan reconstruction algorithm developed herein performed very well in a 19-patient cohort. This algorithm can be incorporated into the clinical process to assist in the assessment of center-specific seed placement accuracy and can be used to gather implant metrics in an automated, standardized fashion for future PBSI trials.
Salvage external beam radiation therapy (EBRT) followed by interstitial brachytherapy is commonly used to treat patients with vaginal recurrence of endometrial cancer. The evidence for this is ...typically limited to case series treating small volumes of disease. For the present study, 12 consecutive patients with locally advanced, biopsy‐proven vaginal recurrence after surgically treated endometrial cancer who received salvage EBRT (45 Gy in 25 daily fractions to microscopic disease and 55–57.5 Gy to gross nodal disease) with magnetic resonance‐guided interstitial brachytherapy (20–21 Gy in 3 fractions over 2 days) were retrospectively reviewed. The median tumor size of recurrent disease on magnetic resonance imaging was 5 (3–6) cm. Three (25%) tumors involved the bladder wall, three (25%) involved the urethra, and four (33%) extended to the pelvic sidewall. Four (25%) patients had gross nodal disease. On follow‐up, no (0%) patient developed local recurrence. One patient (8%) developed nodal recurrence outside of the radiotherapy treatment volume and then distant metastases, and one patient (8%) developed distant metastasis 2.5 years post‐treatment and subsequently died from the disease. No (0%) other deaths were reported. Zero patients (0%) developed grade ≥4 bowel or bladder toxicity. These data support EBRT with interstitial brachytherapy using modern techniques for locally advanced, vaginal recurrences of endometrial cancer.
•Resource constraints have led to prolonged wait-times for prostate brachytherapy.•Increased wait times predict a significant increase in recurrence and metastases.•Better resource planning is needed ...to reduce management delays & improve outcomes.
It has previously been shown that increased wait times for prostatectomy are associated with poorer outcomes in intermediate-risk prostatic carcinoma (PCa). However, the impact of wait times on PCa outcomes following low-dose-rate brachytherapy (LDR-BT) are unknown.
We retrospectively reviewed 466 intermediate-risk PCa patients that underwent LDR-BT at a single comprehensive cancer center between 2003 and 2016. Wait times were defined as the time from biopsy to LDR-BT. The association of wait times with outcomes was evaluated using Cox and Fine-Gray regression in both univariate and multivariate models.
Median (interquartile range) follow-up and wait time for all patients were 8.1 (6.3–10.4) years and 5.1 (3.9–6.9) months, respectively. Among NCCN unfavourable intermediate-risk (UIR) patients (n = 170; 36%), increased wait times predicted both a greater cumulative incidence of recurrence MHR = 1.01/month of wait time (95% CI: 1.00–1.03); P = 0.044 and metastases MHR = 1.04/month of wait time (95% CI: 1.02–1.06); P < 0.001 in multivariate modeling. In NCCN favourable intermediate-risk (FIR) patients, there was no significant association between wait time and recurrence or metastases risk. Among all intermediate-risk patients, wait time was associated with an increase in the incidence of metastases MHR = 1.03/month of wait time (95% CI: 1.02–1.05); P < 0.001, but not recurrence in multivariate models. There was no association between wait time and overall survival in the UIR, FIR, or all intermediate-risk cohorts.
Resource constraints within this center’s public healthcare system have contributed to waitlists exceeding 5-months in length. This study finds that patients with UIR PCa experience a 1% increase in the risk of recurrence and 4% increase in the risk of metastases with each additional month of delay in definitive disease management. Preventing such extended management delays in LDR-BT may improve disease-related outcomes in patients with PCa.
To develop a model for prostate specific antigen (PSA) values at one year among patients treated with intraoperatively planned
I prostate brachytherapy (IOPB).
Four hundred and deven patients treated ...with IOPB for prostate adenocarcinoma were divided into four groups: those with PSA values ≥ 3 ng/ml; < 3 and ≥ 2; < 2 and ≥ 1 or PSA < 1 between 10.5 and 14.5 months post implantation (1yPSA). Ordinal regression analysis was then performed between patient, tumor, and treatment characteristics. 1yPSA values were also compared with toxicity outcomes.
Median 1yPSA was 0.77 (0.04-17.36). Thirty-two patients (8%) had a PSA ≥ 3; 35 (9%) had PSA < 3, ≥ 2; 87 (21%) had PSA < 2, ≥ 1, and most patients 254 (62%) had PSA < 1. PSA response was independent of gland volume, Gleason score, clinical stage, seed activity, V
, V
, D
, or number of needles and seeds used. Older patients had significantly lower 1yPSA; median ages 65.1 (46.5-81.0), 62.1 (50.4-79.5), 60.5 (47.1-80.3), and 58.1 (45.1-74.2) years for each of the 1yPSA groups respectively (
< 0.001). Also, both implant V
(
< 0.001) and initial PSA values (
= 0.04) were predictive of 1yPSA values. There was no correlation between 1yPSA values and toxicity encountered.
PSA response at 1 year post IOPB appears to be dependent on patient age, initial PSA, and implant V
. Our results provide reassurance that parameters other than biochemical failure influence 1yPSA values.
Perineal template-based interstitial gynecologic brachytherapy (ISBT) treatments are evaluated to determine whether adaptive inter-fraction re-planning is beneficial and necessary to meet the ...treatment aims of the American Brachytherapy Society (ABS) consensus guidelines for interstitial brachytherapy. Adherence to the EMBRACE II protocol is also assessed.
Ten patients receiving radical intent treatment for locally advanced or recurrent gynecologic malignancies underwent a three-fraction ISBT treatment with an ABS-recommended prescription regimen of 21 to 24 Gy. Clinical treatment plans were created according to a computed tomography (CT) acquired immediately post-implant. The first fraction was delivered on the same day as the implant (Day 1). The remaining two fractions were delivered on the next day (Day 2), at least six hours apart. Prior to treating on Day 2, a verification CT was acquired, permitting assessment of over-night changes. The Day 2 CT was used to evaluate deviations in 2-Gy-per-fraction equivalent dose (EQD
) from the clinically intended dosimetry for clinical target volume (CTV), bladder, rectum, and sigmoid.
For all patients, the median (range) difference between the intended and the delivered dosimetry for the CTV D90% was 1.4 Gy
(0.3-4.4 Gy
). For all normal tissues, the median (range) difference from the intended normal tissue dose was 2.6 Gy
(0.1-15.5 Gy
). In all cases, the deviation from clinically intended dosimetry did not lead to a violation of recommended normal tissue dose guidelines. For two of 10 patients with large normal tissue differences (> 10 Gy
from the intended dose), inter-fraction adaptive planning did improve the plan quality, but was not strictly required to meet the normal tissue dose planning aims.
The implementation of perineal template-based ISBT treatment without inter-fraction adaptive planning can be delivered to comply with the ABS normal tissue dose guidelines and EMBRACE II limits for prescribed dose.
To compare the outcomes of patients with intermediate risk prostate cancer (IR-PCa) treated with low-dose rate I-125 seed brachytherapy (LDR-BT) and targeted dose painting of a histologic dominant ...intra-epithelial lesion (DIL) to those without a DIL.
455 patients with IR-PCa were treated at a single center with intra-operatively planned LDR-BT, each following the same in-house dose constraints. Patients with a DIL on pathology had hot spots localized to that region but no specific contouring during the procedure.
396 (87%) patients had a DIL. Baseline tumor characteristics and overall prostate dosimetry were similar between patients with and without DIL except the median number of biopsy cores taken: 10 (10–12) vs 12 (10–12) (p = 0.002).
19 (5%) and 18 (5%) of patients with and 1 (2%) and 0 (0%) of those without DIL experienced CTCAE grade 2 and 3 toxicity respectively. Overall, toxicity grade did not significantly correlate with presence of DIL (p = 0.10).
Estimated 7-year freedom from biochemical failure (FFBF) was 84% (95% confidence interval: 79–89) and 70% (54–89) in patients with and without a DIL (log-rank p = 0.315). In DIL patients, cox regression revealed location of DIL (“Base” vs “Apex” HR: 1.03; 1.00–1.06; p = 0.03) and older age (70 vs 60 HR: 1.62; 1.06–2.49; p = 0.03) was associated with poor FFBF.
Targeting DIL through dose painting during intraoperatively planned LDR-BT provided no statistically significant change in FFBF. Patients with DILs in the prostate base had slightly lower FFBF despite DIL boost.
Radiation physics; Surgery; Cancer surgery; Urology; Oncology; Prostate cancer; Brachytherapy; Low-dose-rate.
The objective of this study was to compare the relative utility of tissue harmonic (H) and brightness (B) transrectal ultrasound (TRUS) images of the prostate by studying interobserver and ...intraobserver variation in prostate delineation.
Ten patients with early-stage disease were randomly selected. TRUS images of prostates were acquired using B and H modes. The prostates on all images were contoured by an experienced radiation oncologist (RO) and five equally trained observers. The observers were blinded to information regarding patient and imaging mode. The volumes of prostate glands and areas of midgland slices were calculated. Volumes contoured were compared among the observers and between observer group and RO. Contours on one patient were repeated five times by four observers to evaluate the intraobserver variability.
A one-sample Student t-test showed the volumes outlined by five observers are in agreement (p > 0.05) with the RO. Paired Student t-test showed prostate volumes (p = 0.008) and midgland areas (p = 0.006) with H mode were significantly smaller than that with B mode. Two-factor analysis of variances showed significant interobserver variability (p < 0.001) in prostate volumes and areas. Inter- and intraobserver consistency was quantified as the standard deviation of mean volumes and areas, and concordance indices. It was found that for small glands (≤35 cc) H mode provided greater interobserver consistency; however, for large glands (≥35 cc), B mode provided more consistent estimates.
H mode provided superior inter- and intraobserver agreement in prostate volume definition for small to medium prostates. In large glands, H mode does not exhibit any additional advantage. Although harmonic imaging has not proven advantageous for all cases, its utilization seems to be judicious for small prostates.
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