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The AAPM & GEC-ESTRO Task Group No. 192 Report was published in 2014. Since then, improvements in robotic brachytherapy technology have been realized and a large number of new robotic systems were developed. In addition, progress has been made on translating some of these devices from laboratory to clinical practice. In response to these advances, the AAPM Brachytherapy subcommittee and GEC-ESTRO BRAPHYQS subcommittee convened a joint task group (TG-342) charged with updating the TG-192 report and providing comprehensive guidelines for implementation of these robotic devices in the clinic. The current report (TG-342) mainly focuses on newer robotic systems available or reported since 2013. The TG-342 committee has gathered information from literature and drafted a report. There is minimal or no overlap with TG-192, so far the robotic systems are concerned. However, there are some overlaps in the methodology of clinical applications and recommendations. Several robotics systems described in the TG-192 Report have gone through major modifications, whereas some of them are now discontinued. Several new robotic systems (not reported in TG-192) have successfully been translated to clinical use and the reported clinical outcomes are encouraging. In TG-342, eighteen new robotic systems have been described and their specifications, status and applications have been illustrated. In TG-192 Report, 13 robotic systems were presented. Most of the new systems in TG-342 (18 in total) differ from each other with respect to available features, functionalities and levels of automation. The systems are either US guided or CT guided, only 3 systems are MRI guided. About half of the systems are needle guides with manual needle insertion, the other half accommodates autonomous needle insertion. Reported accuracy of needle tip placement in a phantom ranges from 0.9 to 2.9 mm. Few of them have been developed for other needle-based procedures such as biopsy, RFA, etc. However, these systems are also being considered for brachytherapy with minor modifications. The robotic assistance in clinical applications for LDR (permanent seed/source implantation) remains almost the same, while the applications for HDR procedures with robotic assistance have been elaborated. In addition, the recommendation section has been expanded. International efforts in developing brachytherapy robots have been realized; the vast majority of the new systems are reported from Asia and Europe (17 out of 18). Some of those robotic systems have been used clinically. Due to the wide variability among the available robotic systems, various sections such as safety, commissioning, and recommendations have been written focusing on brachytherapy procedures rather than any specific robotic system. Current available brachytherapy robotic systems greatly vary in design, characteristics, features, and imaging modalities. Therefore, the TG-342 report provides general rather than very strict recommendations and encourages all researchers to develop and document their own calibration procedures specific for their robotic system. The final draft of TG-342 report is ready for review and approval by the parent committees. [ABSTRACT FROM AUTHOR]

Abstract: Purpose: Delivering adequate dose to tracheal mucosa recurrence after multiple prior courses of surgery and radiation presented a challenge for radiation delivery. Tumor bed location and size, combined with previous doses to surrounding areas, complicated the use of external beam therapy with either photons or electrons. High-dose-rate (HDR) brachytherapy was explored to provide sufficient dose coverage. Methods and Materials: A 45-year-old gentleman presented with recurrent head and neck cancer. After undergoing additional excision of gross tumor in the tracheal region, radiation was recommended to improve local control. The region of residual tumor was confined to a small superficial lesion at the posterior–superior aspect of the trachea, involving mucosa located along the bend of the trachea, immediately deep to the stoma. External beam treatment was discussed but was not recommended based on recurrence location in the prior radiation field and patient’s flexed chin position. HDR technique with a custom applicator was preferred. Results: A three-dimensional HDR plan based on computed tomography used a single catheter optimized to cover gross tumor volume as delineated by physician. Prescribed dose was 5Gy/fraction for six fractions (two fractions/wk). The applicator position was verified daily with computed tomography and physician setup approval before treatment. The patient was positioned on a wing board to allow access to the stoma. HDR brachytherapy was well tolerated. Conclusions: Intraluminal HDR brachytherapy is a viable option for providing dose to region inside tracheal stoma. Advantages over photon and electron beam therapy include reduced dose to surrounding tissues previously irradiated, skin dose, and reproducibility of treatment delivery. [Copyright &y& Elsevier]

Abstract: Purpose: Intra-operative (real-time) treatment planning has been adapted by many institutions for low–dose rate prostate brachytherapy. Although this allows dosimetric planning to be done during the procedure, preplan imaging to obtain a prostate volume is essential to identify the number of seeds to ensure adequate volume coverage. Currently, there is no consensus regarding the most appropriate imaging to obtain this information. We conducted a retrospective study to compare how volumes obtained from preplan CT (p-CT) scans or preplan transrectal ultrasound (p-TRUS) correlated with real-time ultrasound and postimplant CT volumes and the difference in accuracy of seed estimation between these techniques. Methods and Materials: Ninety-two patients underwent 125I permanent seed implants at Thomas Jefferson University Hospital between February 2002 and August 2008. Fifty-one patients underwent p-TRUS before intra-operative planning and 41 patients were evaluated by p-CT. Results: The median difference in volume between preimplant imaging and the intra-operative planning ultrasound was 3.59 and 5.2cc for patients who underwent p-TRUS and p-CT, respectively. p-TRUS volumes more closely correlated with real-time intra-operative volumes (R =0.84 in all patients and R =0.91 in hormone-naïve patients) vs. p-CT (R =0.82). The median number of seeds wasted using p-CT was 18 vs. 7 using volumes derived from p-TRUS. Conclusions: The number of seeds ordered could be more accurately obtained from p-TRUS volumes, and this translated into less seed wastage. Our findings indicate that p-TRUS is a more accurate and an economically superior alternative to p-CT imaging in the era of real-time ultrasound planning. [ABSTRACT FROM AUTHOR]

Abstract: Purpose: Providing adequate dosimetric coverage of elongated, curvilinear incisions during adjuvant intensity-modulated radiation therapy (IMRT) after extrapleural pneumonectomy (EPP) for malignant pleural mesothelioma (MPM) creates technical challenges. We explored high-dose-rate (HDR) surface brachytherapy to supplement dose to multiple curvilinear incisions. This modality circumvents the technical limitations of relying on multiple en face electron fields while minimizing dose to adjacent normal tissues. Methods and Materials: A 59-year-old man presented with a left-sided, Stage III, T3N2M0, epithelioid MPM. After undergoing a left EPP, adjuvant IMRT was recommended to improve local control. An eight-field IMRT plan was designed to encompass the postoperative hemithorax. Incisional scars were lengthy and extended beyond the hemithoracic target volume. Both en face electron and surface HDR plans were prepared and evaluated based on dosimetric coverage of the incisional scars, dose to normal tissues, reliability of setup, and treatment delivery. Results: HDR was preferred. The patient was planned and treated in the right lateral decubitus position. HDR source catheters were placed along the incisions atop 5-mm bolus. A composite plan including IMRT and brachytherapy dose contributions was produced. Boosts of incisional scars were performed in six fractions (three fractions per week) of 3Gy prescribed to 12mm from the catheter. HDR brachytherapy was well tolerated. Conclusions: Surface HDR brachytherapy is a viable option for supplemental dose to incisional scars at risk of local recurrence after EPP for MPM. Advantages over electron beam therapy include avoidance of field abutments and feathering, less tissue–bone interface dose uncertainty and reproducibility of treatment delivery. [Copyright &y& Elsevier]

Abstract: Purpose: To study the impact of seed localization, as performed by different observers using linked 125I seeds, on postimplant dosimetry in prostate brachytherapy and, to compare transrectal ultrasound (TRUS)-based with CT-based approach for the dosimetric outcomes. Methods and Materials: Nineteen permanent prostate implants were conducted using linked 125I seeds. Postimplant TRUS and CT images were acquired and prostate glands were, after implantation, delineated on all images by a single oncologist, who had performed all 19 seeding procedures. Six observers independently localized the seeds on both TRUS and CT images, from which the principle dosimetric parameters V 100 (volume of prostate that received the prescribed dose), V 150 (volume of prostate that received 150% of the prescribed dose), and D 90 (minimal dose delivered to 90% of the prostate) were directly calculated for each patient. A single-factor analysis of variance was first applied to determine interobserver variability in seed localization. A nonparametric comparison of the approach using TRUS and CT was then carried out by the Wilcoxon paired-sample test. Results: Analysis from the analysis of variance for TRUS showed that the null hypothesis for equal means, could not be rejected for all six observers based on a significance level α =0.05. TRUS-based and CT-based approaches were then cross compared by the Wilcoxon paired-sample test, which suggested that the null hypothesis was insignificant for V 100 and D 90, but was significant for V 150. Conclusions: Both TRUS- and CT-imaging modalities provided indistinguishable postimplant dosimetry results as far as V 100 and D 90 were concerned. There was comparable observer independence between TRUS- and CT-based seed localization for linked-seed implant procedures. With other advantages that TRUS-imaging modality had over CT in the evaluation of postimplant dosimetry, TRUS would be a preferred choice in conjunction with linked seeds for intraoperative procedures in prostate brachytherapy. [Copyright &y& Elsevier]

Abstract: Purpose: To examine the dosimetric feasibility of a conical implantation approach to robotic-assisted prostate brachytherapy. Methods and materials: An in-house inverse planning software based on the genetic algorithm (GA) was used to optimize the needle angulations and the seed positions along needles that form one or two bouquets. Volume data from 20 prostate seed implant patients (six 125I and 14 103Pd) previously treated using the conventional rectilinear template approach were used. The dosimetry outcomes of the optimized treatment plan in the conical approach were compared with those from the original treatment plans based on the conventional rectilinear template approach. Results: When seed spacing is restricted to nominal 1 cm center-to-center spacing, dosimetry results in the conical approach suffer from a higher urethra dose and higher dose heterogeneity compared with the original rectilinear template plans. When the seed loading patterns are optimized as part of inverse planning, the resulting dosimetry plans exhibit adequate dose coverage and uniformity through the target volume, as well as satisfactory sparing of the urethra and rectum. Conclusions: Conically spaced implantation for prostate brachytherapy with 125I and 103Pd seeds is feasible in terms of dosimetry outcomes. Techniques for optimized inverse planning for this approach have been developed. [Copyright &y& Elsevier]