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Purpose: Recommendations of the American Association of Physicists in Medicine (AAPM) and the European Society for Radiotherapy and Oncology (ESTRO) on dose calculations for high-energy (average energy higher than 50 keV) photon-emitting brachytherapy sources are presented, including the physical characteristics of specific 192Ir, 137Cs, and 60Co source models. Methods: This report has been prepared by the High Energy Brachytherapy Source Dosimetry (HEBD) Working Group. This report includes considerations in the application of the TG-43U1 formalism to high-energy photon-emitting sources with particular attention to phantom size effects, interpolation accuracy dependence on dose calculation grid size, and dosimetry parameter dependence on source active length. Results: Consensus datasets for commercially available high-energy photon sources are provided, along with recommended methods for evaluating these datasets. Recommendations on dosimetry characterization methods, mainly using experimental procedures and Monte Carlo, are established and discussed. Also included are methodological recommendations on detector choice, detector energy response characterization and phantom materials, and measurement specification methodology. Uncertainty analyses are discussed and recommendations for high-energy sources without consensus datasets are given. Conclusions: Recommended consensus datasets for high-energy sources have been derived for sources that were commercially available as of January 2010. Data are presented according to the AAPM TG-43U1 formalism, with modified interpolation and extrapolation techniques of the AAPM TG-43U1S1 report for the 2D anisotropy function and radial dose function. [ABSTRACT FROM AUTHOR]

This paper presents the recommendations of the American Association of Physicists in Medicine (AAPM) and the European Society for Therapeutic Radiology and Oncology (ESTRO) on the dosimetric parameters to be characterized, and dosimetric studies to be performed to obtain them, for brachytherapy sources with average energy higher than 50 keV that are intended for routine clinical use. In addition, this document makes recommendations on procedures to be used to maintain vendor source strength calibration accuracy. These recommendations reflect the guidance of the AAPM and the ESTRO for its members, and may also be used as guidance to vendors and regulatory agencies in developing good manufacturing practices for sources used in routine clinical treatments. [ABSTRACT FROM AUTHOR]

Summary: Lumpectomy and whole-breast radiotherapy (ie, breast-conservation treatment) are accepted as viable alternatives to mastectomy in locoregional management of breast cancer. These techniques are used to keep morbidity to a minimum, optimise cosmesis, and maintain treatment outcomes. Pathological and clinical data suggest that most recurrences of cancer in the ipsilateral breast are in the vicinity of the index lesion, and that remote recurrences are uncommon, whether or not whole-breast radiotherapy is delivered. These data lend support to the idea of partial-breast radiotherapy. Such a restricted treatment volume allows safe delivery of an accelerated hypofractionated regimen over a shortened course of 1 week. This technique differs from that of standard whole-breast tangential external-beam radiotherapy and necessitates investigation of accelerated partial-breast irradiation (APBI). Several techniques of APBI are being investigated; however, most experience, and the most favourable early outcomes, has been obtained with image-guided breast brachytherapy. This review highlights the rationale and outcomes of brachytherapy techniques. [Copyright &y& Elsevier]

Abstract: Purpose: Quality assurance for complex high-dose-rate (HDR) treatment planning has always been a challenge to the physics community because of the time constraint between HDR planning and the delivery of the treatment. This study proposes an efficient, precise, and easy method for checking the complex computer calculation. Methods and materials: Posttreatment, three-dimensional dose–volume study was performed for 98 patients with 128 new treatment plans along with 30 library plans. Volumes covered by the 100% isodose line, source activity (Ci), total dwell time (s), and the prescription dose (100%) were recorded. Variation of R V defined as (irradiated time×activity/elongation factor×prescribed dose) with volume was studied for different catheter systems. Results: Parametric fit of R V with volume for three different systems that cover most of the interstitial and intracavitary brachytherapy implants agrees within ±6%. Conclusions: The excellent agreement of R V derived from this simplistic point source model with three-dimensional dose calculations for individual HDR treatment plans clearly establishes that for an implant with known number of catheters, the time needed to deliver a prescribed dose to a given prescription volume can be easily predicted. [Copyright &y& Elsevier]

Abstract: Purpose: Several recent studies indicate high-dose-rate (HDR) breast brachytherapy as an alternative to standard external beam radiation therapy for partial breast irradiation with high dose conformality to the target. However, this article presents an exploration of the possibility of achieving higher conformal avoidance of sensitive structures through detailed and comparative 3D CT-based anatomical dose distribution of a patient in supine and prone positions. Methods and materials: A patient treated with accelerated partial breast HDR breast brachytherapy in the supine position was selected for two CT-based analyses, one in the supine and one in the prone position. The optimized plan (Nucletron HDR planning station) for each position was achieved using graphical optimization with local adjustment of isodose lines to cover the planned target volume (PTV, lumpectomy with 2 cm margin) with 100% of the prescribed dose (34 Gy in 10 fractions) while minimizing the hot spots. Cumulative dose-volume histograms (DVH) were analyzed for the PTV, lung, skin, pectoral muscle, and chest wall. Results: The PTV received 100% of prescribed dose in both the prone and supine positions. A significant (>40%) dose reduction was achieved in the lung in the prone treatment position. Similar dose reductions were also achieved for prone pectoral muscle, chest wall, and breast skin, irradiating less volume with high doses. Pectoral muscle, lumpectomy, and the breast skin showed prominent differences in shape and displacement in the prone compared with the supine position. Conclusion: CT-based treatment planning allowed calculations of volumetric dose distribution to the target and all sensitive structures with proper visualization and volumetric delineation of organs of interest. The treatment plan shows significant dose reduction may be possible in various sensitive structures if the patient is treated with HDR brachytherapy in the prone position. [Copyright &y& Elsevier]

Purpose: Although accelerated partial breast irradiation (APBI) as the sole radiation modality after lumpectomy has shown promising results for select breast cancer patients, published experiences thus far have provided limited information on treatment planning methodology and quality assurance measures. A novel three-dimensional computed tomography (CT)-based treatment planning method for accurate delineation and geometric coverage of the target volume is presented. A correlation between treatment volume and irradiation time has also been studied for quality assurance purposes. Methods and Materials: Between May 2002 and January 2003, 50 consecutive patients underwent an image-guided interstitial implant followed by CT-based treatment planning and were subsequently treated with APBI with a high-dose-rate (HDR) brachytherapy remote afterloader. Target volume was defined as the lumpectomy cavity +2 cm margin modified to >/=5 mm to the skin surface. Catheter reconstruction, geometric optimization, and manual adjustment of irradiation time were done to optimally cover the target volume while minimizing hot spots. Dose homogeneity index (DHI) and percent of target volume receiving 100% of the prescription dose (32 Gy in 8 fractions or 34 Gy in 10 fractions) was determined. Additionally, the correlation between the treatment volume and irradiation time, source strength, and dose was then analyzed for manual verification of the HDR computer calculation. Results: In all cases, the lumpectomy cavity was covered 100%. Target volume coverage was excellent with a median of 96%, and DHI had a median value of 0.7. For each plan, source strength times the treatment time for every unit of prescribed dose had an excellent agreement of +/-7% to the Manchester volume implant table corrected for modern units. Conclusions: CT-based treatment planning allowed excellent visualization of the lumpectomy cavity and normal structures, thereby improving target volume delineation and optimal coverage, relative to conventional orthogonal film dosimetry. Using the Manchester volume implant table calculated irradiation time can be used as quality assurance for the HDR computed time. Thus dosimetric quality assurance and adequate target volume coverage can be concurrently confirmed, allowing prospective evaluation and optimization of implants. [ABSTRACT FROM AUTHOR]

Purpose: To compare dosimetrically four different techniques of accelerated partial breast irradiation (APBI) in the same patient. Methods and Materials: Thirteen post-lumpectomy interstitial brachytherapy (IB) patients underwent imaging with preimplant computed tomography (CT) in the prone and supine position. These CT scans were then used to generate three-dimensional conformal radiotherapy (3D-CRT) and prone and supine helical tomotherapy (PT and ST, respectively) APBI plans and compared with the treated IB plans. Dose–volume histogram analysis and the mean dose (NTDmean) values were compared. Results: Planning target volume coverage was excellent for all methods. Statistical significance was considered to be a p value <0.05. The mean V100 was significantly lower for IB (12% vs. 15% for PT, 18% for ST, and 26% for 3D-CRT). A greater significant differential was seen when comparing V50 with mean values of 24%, 43%, 47%, and 52% for IB, PT, ST, and 3D-CRT, respectively. The IB and PT were similar and delivered an average lung NTDmean dose of 1.3 Gy3 and 1.2 Gy3, respectively. Both of these methods were statistically significantly lower than the supine external beam techniques. Overall, all four methods yielded similar low doses to the heart. Conclusions: The use of IB and PT resulted in greater normal tissue sparing (especially ipsilateral breast and lung) than the use of supine external beam techniques of 3D-CRT or ST. However, the choice of APBI technique must be tailored to the patient’s anatomy, lumpectomy cavity location, and overall treatment goals. [Copyright &y& Elsevier]

To create and test a multipurpose brachytherapy catheter prototype enabling intratumoral injection and brachytherapy after a single catheter insertion. The design of the prototype consists of an outer tube and an inner syringe tube that can be filled with injectable agent. The outer sheath and inner syringe tube were constructed using polytetrafluoroethylene tubing, and the other components were 3D printed using dental resin and polylactic acid material. To demonstrate functionality, we injected in vitro phantoms with dyed saline. For proof of concept, we demonstrated the potential for the prototype to deliver cell therapy, enhance tumor delineation, deliver tattoo ink for pathology marking, avoid toxicity through local delivery of chemotherapy, and facilitate combination brachytherapy and immunotherapy. The prototype enables accurate injection in vitro and in vivo without altering dosimetry. To illustrate the potential for delivery of cell therapies, we injected luciferase-expressing splenocytes and confirmed their delivery with bioluminescence imaging. To demonstrate feasibility of radiographically visualizing injected material, we delivered iohexol contrast intratumorally and confirmed tumor retention using Faxitron x-ray imaging. In addition, we show the potential of intratumoral administration to reduce toxicity associated with cyclophosphamide compared with systemic administration. To demonstrate feasibility, we treated tumor-bearing mice with brachytherapy (192Ir source, 2 Gy to 5 mm) in combination with intratumoral injection of 375,000 U of interleukin 2 and observed no increased toxicity. These results demonstrate that a prototype multipurpose brachytherapy catheter enables accurate intratumoral injection and support the feasibility of combining intratumoral injection with brachytherapy. [ABSTRACT FROM AUTHOR]

Purpose To characterize image quality and feasibility of using ViewRay MRI (VR)–guided brachytherapy planning for cervical cancer. Methods and Materials Cervical cancer patients receiving intracavitary brachytherapy with tandem and ovoids, planned using 0.35T VR MRI at our institution, were included in this series. The high-risk clinical target volume (HR-CTV), visible gross tumor volume, bladder, sigmoid, bowel, and rectum contours for each fraction of brachytherapy were evaluated for dosimetric parameters. Typically, five brachytherapy treatments were planned using the T2 sequence on diagnostic MRI for the first and third fractions, and a noncontrast true fast imaging with steady-state precession sequence on VR or CT scan for the remaining fractions. Most patients received 5.5 Gy × 5 fractions using high-dose-rate Ir-192 following 45 Gy of whole-pelvis radiotherapy. The plan was initiated at 5.5 Gy to point A and subsequently optimized and prescribed to the HR-CTV. The goal equivalent dose in 2 Gy fractions for the combined external beam and brachytherapy dose was 85 Gy. Soft-tissue visualization using contrast-to-noise ratios to distinguish normal tissues from tumor at their interface was compared between diagnostic MRI, CT, and VR. Results One hundred and forty-two fractions of intracavitary brachytherapy were performed from April 2015 to January 2017 on 29 cervical cancer patients, ranging from stages IB1 to IVA. The median HR-CTV was 27.78 cc, with median D 90 HR-CTV of 6.1 Gy. The median time from instrument placement to start of treatment using VR was 65 min (scan time 2 min), compared to 105 min using diagnostic MRI (scan time 11 min) ( t -test, p < 0.01). The contrast-to-noise ratio of tumor to cervix in both diagnostic MRI and VR had significantly higher values compared to CT (ANOVA and t-tests, p < 0.01). Conclusions We report the first clinical use of VR-guided brachytherapy. Time to treatment using this approach was shorter compared to diagnostic MRI. VR also provided significant advantage in visualizing the tumor and cervix compared to CT. This presents a feasible and reliable manner to image and plan gynecologic brachytherapy. [ABSTRACT FROM AUTHOR]

Purpose The purpose of the study was to describe the clinical utilization of a novel Double-Balloon applicator for accelerated partial breast irradiation (APBI). Methods and Materials The Double-Balloon single-entry breast applicator contains a single central treatment catheter, as well as four peripheral catheters that can be differentially loaded to customize radiation dose coverage. An inner balloon is filled with up to 7–30 cm 3 of saline to increase separation between the peripheral catheters, and an outer balloon is filled with up to 37–115 cm 3 of saline to displace breast tissue from the peripheral catheters. Treatment planning objectives include coverage of the breast planning target volume to a minimum of V 90 > 90%, limiting dose heterogeneity such that V 200 < 10 cm 3 and V 150 < 50 cm 3 , and limiting maximum dose to skin (<100% of prescription dose) and ribs (<145% of prescription dose). Results High-dose-rate APBI was delivered to 11 women using this device (34 Gy in 10 twice daily fractions). The mean V 90 was 98.2% (range 94.2–99.4%). The mean skin D max with the Double-Balloon applicator was 83.3% (range 75.6–99.5%). The mean breast V 200 was 5.8 cm 3 (range 2.3–10.2 cm 3 ), and the mean breast V 150 was 32.9 cm 3 (range 25.0–41.7 cm 3 ). Pretreatment quality assurance was performed using CT prior to each morning fraction and ultrasound prior to each afternoon fraction. Conclusions The Double-Balloon applicator can be easily introduced into a previously existing brachytherapy program. APBI plans created with this applicator achieve excellent planning target volume coverage, while limiting skin dose and maintaining breast V 200 < 10 cm 3 . [ABSTRACT FROM AUTHOR]

Purpose: To evaluate outcomes among women with American Society for Radiation Oncology (ASTRO) consensus statement cautionary features treated with brachytherapy-based accelerated partial breast irradiation (APBI). Methods and Materials: Between March 2001 and June 2006, 322 consecutive patients were treated with high-dose-rate (HDR) APBI at the University of Wisconsin. A total of 136 patients were identified who met the ASTRO cautionary criteria. Thirty-eight (27.9%) patients possessed multiple cautionary factors. All patients received 32 to 34 Gy in 8 to 10 twice-daily fractions using multicatheter (93.4%) or Mammosite balloon (6.6%) brachytherapy. Results: With a median follow-up of 60 months, there were 5 ipsilateral breast tumor recurrences (IBTR), three local, and two loco-regional. The 5-year actuarial rate of IBTR was 4.8% ± 4.1%. The 5-year disease-free survival was 89.6%, with a cause-specific survival and overall survival of 97.6% and 95.3%, respectively. There were no IBTRs among 32 patients with ductal carcinoma in situ (DCIS) vs. 6.1% for patients with invasive carcinoma (p = 0.24). Among 104 patients with Stage I or II invasive carcinoma, the IBTR rate for patients considered cautionary because of age alone was 0% vs. 12.7% in those deemed cautionary due to histopathologic factors (p = 0.018). Conclusions: Overall, we observed few local recurrences among patients with cautionary features. Women with DCIS and patients 50 to 59 years of age with Stage I/II disease who otherwise meet the criteria for suitability appear to be at a low risk of IBTR. Patients with tumor-related cautionary features will benefit from careful patient selection. [ABSTRACT FROM AUTHOR]

Abstract: Purpose: A new form of partial breast irradiation (PBI), ClearPath (CP) breast brachytherapy, has been introduced. We present our results of a dosimetric comparison of MammoSite® (MS) and CP PBI. Methods and Materials: The dimensions of the CP device were reconstructed onto the MS planning CT scans for 15 previously treated patients. The mean %V 100, %V 150, %V 200 (percent of the PTV that received 100%, 150%, and 200% of the prescription dose, respectively), ipsilateral breast %V 50 (percent of the ipsilateral normal breast that received 50% of the prescription dose), ipsilateral lung %V 30 (percent of the ipsilateral lung that received 30% of the prescription dose), the heart %V 5 (percent of the heart that received 5% of the prescription dose), and the maximum skin point dose per fraction were then determined for each patient using the two methods of balloon-based PBI. Results: The mean %V 100 was 96.5% vs. 96.5%, the mean %V 150 was 42.1% vs. 42.9% (p =ns), and the mean V 200 was 11.4% vs. 15.2% (p <.05) for the MS and CP methods, respectively. The mean ipsilateral breast %V 50 was 19.8% vs.18.0% (p <.05), the mean ipsilateral lung %V 30 was 3.7% vs. 2.8% (p <.05), the mean heart %V 5 was 57.0% vs. 54.3% (p <.05), and the maximum skin point dose per fraction was 312.2 and 273.6cGy (p <.05) for the MS and CP methods, respectively. Conclusions: The MS and CP methods of PBI offer comparable target volume coverage; however, the CP device achieves increased normal tissue sparing. [Copyright &y& Elsevier]

Purpose: To report the local control and overall survival outcomes after lumpectomy followed by accelerated partial breast irradiation in high-risk patients as defined by the current inclusion criteria for the National Surgical Adjuvant Breast and Bowel B-39/Radiation Therapy Oncology Group 0413 Intergroup trial. Methods and Materials: Between 2000 and 2005, 273 women with early-stage breast cancer were treated using either multicatheter interstitial brachytherapy (n = 247) or MammoSite (n = 26). Patients received 32–34 Gy in 8–10 twice-daily fractions using high-dose-rate 192Ir brachytherapy. All patients met the initial inclusion criteria for the Intergroup trial and were separated into two groups: high-risk patients (representing the cohort that remained eligible for the Intergroup trial) who satisfied one or more of the “high-risk” criteria (age <50 years, estrogen receptor negative, and/or positive lymph nodes; n = 90), and low-risk patients who comprised the remainder of the cohort (n = 183). The outcomes of the two cohorts were analyzed and compared. Results: The median follow-up of the entire cohort was 48.5 months. No significant difference was found in outcomes at 5 years between the low- and high-risk groups, with a local control rate of 97.8% vs. 93.6%, crude local recurrence rate of 2.2% (n = 4) vs. 4.4% (n = 4), and overall survival rate of 92.1% vs. 89.5%, respectively. Conclusion: At 5 years, no statistically significant difference was found in outcomes for patients deemed to be at greater risk in the current National Surgical Adjuvant Breast and Bowel B-39/Radiation Therapy Oncology Group 0413 Intergroup trial. These clinical data support the inclusion of this “high-risk” population in this important ongoing study. [Copyright &y& Elsevier]