Catheter-based ultrasound hyperthermia with HDR brachytherapy for treatment of locally advanced cancer of the prostate and cervix

A clinical treatment delivery platform has been developed and is being evaluated in a clinical pilot study for providing 3D controlled hyperthermia with catheter-based ultrasound applicators in conjunction with high dose rate (HDR) brachytherapy. Catheter-based ultrasound applicators are capable of 3D spatial control of heating in both angle and length of the devices, with enhanced radial penetration of heating compared to other hyperthermia technologies. Interstitial and endocavity ultrasound devices have been developed specifically for applying hyperthermia within HDR brachytherapy implants during radiation therapy in the treatment of cervix and prostate. A pilot study of the combination of catheter based ultrasound with HDR brachytherapy for locally advanced prostate and cervical cancer has been initiated, and preliminary results of the performance and heating distributions are reported herein. The treatment delivery platform consists of a 32 channel RF amplifier and a 48 channel thermocouple monitoring system. Controlling software can monitor and regulate frequency and power to each transducer section as required during the procedure. Interstitial applicators consist of multiple transducer sections of 2-4 cm length × 180 deg and 3-4 cm × 360 deg. heating patterns to be inserted in specific placed 13g implant catheters. The endocavity device, designed to be inserted within a 6 mm OD plastic tandem catheter within the cervix, consists of 2-3 transducers × dual 180 or 360 deg sectors. 3D temperature based treatment planning and optimization is dovetailed to the HDR optimization based planning to best configure and position the applicators within the catheters, and to determine optimal base power levels to each transducer section. To date we have treated eight cervix implants and six prostate implants. 100 % of treatments achieved a goal of >60 min duration, with therapeutic temperatures achieved in all cases. Thermal dosimetry within the hyperthermia target volume (HTV) and clinical target volume (CTV) are reported. Catheter-based ultrasound hyperthermia with HDR appears feasible with therapeutic temperature coverage of the target volume within the prostate or cervix while sparing surrounding more sensitive regions. (NIHR01CA122276).

Phase II trial of combined high-dose-rate brachytherapy and external beam radiotherapy for adenocarcinoma of the prostate: preliminary results of RTOG 0321

PURPOSE

To estimate the rate of late Grade 3 or greater genitourinary (GU) and gastrointestinal (GI) adverse events (AEs) after treatment with external beam radiotherapy and prostate high-dose-rate (HDR) brachytherapy.

METHODS AND MATERIALS

Each participating institution submitted computed tomography-based HDR brachytherapy dosimetry data electronically for credentialing and for each study patient. Patients with locally confined Stage T1c-T3b prostate cancer were eligible for the present study. All patients were treated with 45 Gy in 25 fractions using external beam radiotherapy and one HDR implant delivering 19 Gy in two fractions. All AEs were graded according to the Common Terminology Criteria for Adverse Events, version 3.0. Late GU/GI AEs were defined as those occurring >9 months from the start of the protocol treatment, in patients with ≥18 months of potential follow-up.

RESULTS

A total of 129 patients from 14 institutions were enrolled in the present study. Of the 129 patients, 125 were eligible, and AE data were available for 112 patients at analysis. The pretreatment characteristics of the patients were as follows: Stage T1c-T2c, 91%; Stage T3a-T3b, 9%; prostate-specific antigen level ≤10 ng/mL, 70%; prostate-specific antigen level >10 but ≤20 ng/mL, 30%; and Gleason score 2-6, 10%; Gleason score 7, 72%; and Gleason score 8-10, 18%. At a median follow-up of 29.6 months, three acute and four late Grade 3 GU/GI AEs were reported. The estimated rate of late Grade 3-5 GU and GI AEs at 18 months was 2.56%.

CONCLUSION

This is the first prospective, multi-institutional trial of computed tomography-based HDR brachytherapy and external beam radiotherapy. The technique and doses used in the present study resulted in acceptable levels of AEs.

Toward adaptive stereotactic robotic brachytherapy for prostate cancer: demonstration of an adaptive workflow incorporating inverse planning and an MR stealth robot

To translate any robot into a clinical environment, it is critical that the robot can seamlessly integrate with all the technology of a modern clinic. MRBot, an MR-stealth brachytherapy delivery device, was used in a closed-bore 3T MRI and a clinical brachytherapy cone beam CT suite. Targets included ceramic dummy seeds, MR-Spectroscopy-sensitive metabolite, and a prostate phantom. Acquired DICOM images were exported to planning software to register the robot coordinates in the imager's frame, contour and verify target locations, create dose plans, and export needle and seed positions to the robot. The coordination of each system element (imaging device, brachytherapy planning system, robot control, robot) was validated with a seed delivery accuracy of within 2 mm in both a phantom and soft tissue. An adaptive workflow was demonstrated by acquiring images after needle insertion and prior to seed deposition. This allows for adjustment if the needle is in the wrong position. Inverse planning (IPSA) was used to generate a seed placement plan and coordinates for ten needles and 29 seeds were transferred to the robot. After every two needles placed, an image was acquired. The placed seeds were identified and validated prior to placing the seeds in the next two needles. The ability to robotically deliver seeds to locations determined by IPSA and the ability of the system to incorporate novel needle patterns were demonstrated. Shown here is the ability to overcome this critical step. An adaptive brachytherapy workflow is demonstrated which integrates a clinical anatomy-based seed location optimization engine and a robotic brachytherapy device. Demonstration of this workflow is a key element of a successful translation to the clinic of the MRI stealth robotic delivery system, MRBot.

Inverse planning optimization for hybrid prostate permanent-seed implant brachytherapy plans using two source strengths

The purpose is to demonstrate the ability to generate clinically acceptable prostate permanent seed implant plans using two seed types which are identical except for their activity. The IPSA inverse planning algorithms were modified to include multiple dose matrices for the calculation of dose from different sources, and a selection algorithm was implemented to allow for the swapping of source type at any given source position. Five previously treated patients with a range of prostate volumes from 20-48 cm3 were re-optimized under two hybrid scenarios: (1) using 0.32 and 0.51 mGy m2 / h 125I, and (2) using 0.64 and 0.76 mGy m2 / h 125I. Isodose lines were generated and dosimetric indices , V150Prostate, D90Prostate, V150Urethra, V125Urethra, V120Urethra,V100Urethra, and D10Urethra were calculated. The algorithm allows for the generation of single-isotope, multi-activity hybrid brachytherapy plans. By dealing with only one radionuclide, but of different activity, the biology is unchanged from a standard plan. All V100Prostate were within 2.3 percentage points for every plan and always above the clinically desirable 95%. All V150Urethra were identically zero, and V120Urethra is always below the clinically acceptable value of 1.0 cm3. Clinical optimization times for the hybrid plans are still under one minute, for most cases. It is possible to generate clinically advantageous brachytherapy plans (i.e. obtain the same quality dose distribution as a standard single-activity plan) while incorporating leftover seeds from a previous patient treatment. This method will allow a clinic to continue to provide excellent patient care, but at a reduced cost. Multi-activity hybrid plans were equal in quality (as measured by the standard dosimetric indices) to plans with seeds of a single activity. Despite the expanded search space, optimization times for these studies were still under two minutes on a modern day laptop and can be reduced to below one minute in a clinical setting. With the typical cost of a set of PPI seeds on the order of thousands of dollars, it is possible to reduce the cost of brachytherapy treatments by allowing for easier use of seeds left over from a previous patient or unused due to a cancelled treatment.

American Society for Therapeutic Radiology and Oncology (ASTRO) Emerging Technology Committee report on electronic brachytherapy

The development of novel technologies for the safe and effective delivery of radiation is critical to advancing the field of radiation oncology. The Emerging Technology Committee of the American Society for Therapeutic Radiology and Oncology appointed a Task Group within its Evaluation Subcommittee to evaluate new electronic brachytherapy methods that are being developed for, or are already in, clinical use. The Task Group evaluated two devices, the Axxent Electronic Brachytherapy System by Xoft, Inc. (Fremont, CA), and the Intrabeam Photon Radiosurgery Device by Carl Zeiss Surgical (Oberkochen, Germany). These devices are designed to deliver electronically generated radiation, and because of their relatively low energy output, they do not fall under existing regulatory scrutiny of radioactive sources that are used for conventional radioisotope brachytherapy. This report provides a descriptive overview of the technologies, current and future projected applications, comparison of competing technologies, potential impact, and potential safety issues. The full Emerging Technology Committee report is available on the American Society for Therapeutic Radiology and Oncology Web site.

Investigation of geometric distortions on magnetic resonance and cone beam computed tomography images used for planning and verification of high-dose rate brachytherapy cervical cancer treatment

PURPOSE

To measure the amount of geometric distortions present in the three-dimensional imaging modalities--cone beam computed tomography (CBCT) and magnetic resonance imaging (MRI)--used at University of California, San Francisco, CA, for gynecologic high dose rate brachytherapy.

METHODS AND MATERIALS

An MRI- and CT-compatible water phantom with two different sets of support structures was designed and built for this study. The support structures were used to precisely position catheters that were filled with either an MRI contrast agent or a string of radio-opaque markers. The first support structure without anatomy was built to test system-based distortions. A second structure included two types of gynecologic applicators as well as several anatomical structures, including bones and rectum to test object-induced distortions. Images were acquired with CT (for reference), kilovoltage CBCT, and MRI (1.5 T with T1- and T2-weighted images). The difference in catheter positions between the images and the CT images was analyzed.

RESULTS

For CBCT, the mean of the absolute deviations was below 1mm in all directions. The inherent uncertainty in the measurement of distortion was less than 0.5mm. MRI presented mean absolute system-based distortions between 0.6 and 1.1mm in the central region of the image and between 0.7 and 2.3mm in the outer region. Images with the applicator and anatomy in place created mean absolute distortions of 0.4, 0.8, and 0.8mm or less for CBCT, MR-T1, and MR-T2 images, respectively.

CONCLUSIONS

The distortions measured in the presence of applicators are small enough to validate the use of CBCT and 1.5 T MRI for GYN brachytherapy treatment planning and verification.

Planning Fireworks Trajectories for Steerable Medical Needles to Reduce Patient Trauma

Accurate insertion of needles to targets in 3D anatomy is required for numerous medical procedures. To reduce patient trauma, a "fireworks" needle insertion approach can be used in which multiple needles are inserted from a single small region on the patient's skin to multiple targets in the tissue. In this paper, we explore motion planning for "fireworks" needle insertion in 3D environments by developing an algorithm based on Rapidly-exploring Random Trees (RRTs). Given a set of targets, we propose an algorithm to quickly explore the configuration space by building a forest of RRTs and to find feasible plans for multiple steerable needles from a single entry region. We present two path selection algorithms with different optimality considerations to optimize the final plan among all feasible outputs. Finally, we demonstrate the performance of the proposed algorithm with a simulation based on a prostate cancer treatment environment.

The temozolomide O6-methylguanine-DNA methyltransferase (MGMT) study: A phase II trial to evaluate the effect of low-dose preoperative neoadjuvant temozolomide on brain tumour MGMT activity in glioma patients

e13027

Background: Epigenetic methylation of the O6-methylguanine-DNA methyltransferase (MGMT) DNA repair gene promoter in tumor tissue from glioblastoma multiforme patients is associated with improved survival after treatment with radiotherapy plus concomitant and adjuvant temozolomide (TMZ). We hypothesized that MGMT promoter methylation mosaicism exists in glial tumors and would affect response to TMZ. Methods: This is a nonrandomized, prospective, open-label, two cohort, single-center phase II study. Twenty-three patients with brain tumors detected by MRI scan and suspected to be gliomas were evaluated. All eligible patients were treatment naive and were self-selected into a TMZ group or a control group. The primary goal of the study was to evaluate the effect of TMZ 75 mg/m2 daily prior to surgery on the brain tumor MGMT expression. Secondary endpoints included safety, tolerability, and MGMT promoter methylation mosaicism in glial tumors. Samples were obtained from multiple regions of each tumor intra-operatively and were analyzed by methylation specific PCR. Results: Our results on MGMT promoter methylation demonstrate that three groups of patients can be identified: Type I: all sites assessed in the tumor demonstrate no methylation of the MGMT promoter; Type II: all sites demonstrate high levels of MGMT promoter methylation; and Type III: a mixed promoter methylation pattern is observed. Conclusions: These results suggest that 1) preoperative neoadjuvant temozolomide is not associated with increased postoperative complications; 2) glial tumors can have very heterogeneous areas of MGMT promoter methylation; and 3) three patterns of MGMT promoter methylation can be discerned. This experimental paradigm may be a useful experimental platform for the assessment of the effect of new drugs at the tumor level.

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High-dose rate brachytherapy using inverse planning simulated annealing for locoregionally advanced cervical cancer: a clinical report with 2-year follow-up

PURPOSE

We present clinical outcomes of image-guided brachytherapy using inverse planning simulated annealing (IPSA) planned high-dose rate (HDR) brachytherapy boost for locoregionally advanced cervical cancer.

METHODS AND MATERIALS

From February 2004 through December 2006, 51 patients were treated at the University of California, San Francisco with HDR brachytherapy boost as part of definitive radiation for International Federation of Gynecology and Obstetrics Stage IB1 to Stage IVA cervical cancer. Of the patients, 46 received concurrent chemotherapy, 43 with cisplatin alone and 3 with cisplatin/5-fluorouracil. All patients had IPSA-planned HDR brachytherapy boost after whole-pelvis external radiation to a total tumor dose of 85 Gy or greater (for alpha/beta = 10). Toxicities are reported according to National Cancer Institute CTCAE v3.0 (Common Terminology Criteria for Adverse Events version 3.0) guidelines.

RESULTS

At a median follow-up of 24.3 months, there were no toxicities of Grade 4 or greater and the frequencies of Grade 3 acute and late toxicities were 4% and 2%, respectively. The proportion of patients having Grade 1 or 2 gastrointestinal and genitourinary acute toxicities was 48% and 52%, respectively. Low-grade late toxicities included Grade 1 or 2 vaginal, gastrointestinal, and hormonal toxicities in 31%, 18%, and 4% of patients, respectively. During the follow-up period, local recurrence developed in 2 patients, regional recurrence developed in 2, and new distant metastases developed in 15. The rates of locoregional control of disease and overall survival at 24 months were 91% and 86%, respectively.

CONCLUSIONS

Definitive radiation by use of inverse planned HDR brachytherapy boost for locoregionally advanced cervical cancer is well tolerated and achieves excellent local control of disease.