Prostate Brachytherapy Program Research Articles

PO0430: Design and Implementation of an Ultrasound-Based High Dose Rate Prostate Brachytherapy (HDR-PB) Program in a Large Academic Center

PO0430: Design and Implementation of an Ultrasound-Based High Dose Rate Prostate Brachytherapy (HDR-PB) Program in a Large Academic Center

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

IntroductionProstate 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.MethodsPatients 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.ResultsSeventeen 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.ConclusionOur department successfully implemented an HDR prostate brachytherapy program. Treatments were effective and there was no grade 3 toxicity to report.

Building a High-Dose-Rate Prostate Brachytherapy Program With Real-Time Ultrasound-Based Planning: Initial Safety, Quality, and Outcome Results

PurposeGrowing evidence supports the efficacy and safety of high-dose-rate (HDR) brachytherapy as a boost or monotherapy in prostate cancer treatment. We initiated a new HDR prostate brachytherapy practice in April 2014. Here, we report the learning experiences, short-term safety, quality, and outcome. Methods and MaterialsFrom April 2014 to December 2017, 164 men were treated with HDR brachytherapy with curative intent. Twenty-eight men (17.1%) underwent HDR brachytherapy as monotherapy, receiving 25 to 27 Gy in 2 fractions. Men treated with HDR brachytherapy as a boost received 19 to 21 Gy in 2 fractions. Fifty-two men (31.7%) had high-risk disease. HDR procedure times, dosimetry, and response were recorded and analyzed. Genitourinary (GU) and gastrointestinal (GI) toxicities were recorded according to the toxicity criteria of the Radiation Therapy Oncology Group. ResultsMean HDR procedure times decreased yearly from 179 minutes in 2014 to 115 minutes in 2017. Median follow-up was 18.6 months (range, 3-55 months). At last review, 79% of patients reported returning to baseline GU status, and 100% of patients noted no change in GI status from their baseline. Four patients experienced acute urinary retention. Treatment planning target volume (PTV) was defined as prostate with margins. Dosimetrically, 97.5% of all HDR implants had PTV D90 ≥100%, 81.5% had PTV V100 ≥95%, 73.6% had maximal urethral doses ≤120%, and 77.5% had rectal 1 mL dose ≤70% (all but one ≤10.8 Gy). The estimated 3-year overall survival was 98.7% (95% confidence interval, 91.4%-99.8%), and disease-free survival was 96.2% (95% confidence interval, 89.5%-98.7%). ConclusionsThe low incidence of GU and GI complications in our cohort demonstrates that a HDR brachytherapy program can be successfully developed as a treatment option for patients with localized prostate cancer.

Transitioning From a Low-Dose-Rate to a High-Dose-Rate Prostate Brachytherapy Program: Comparing Initial Dosimetry and Improving Workflow Efficiency Through Targeted Interventions

PurposeWe transitioned from a low-dose-rate (LDR) to a high-dose-rate (HDR) prostate brachytherapy program. The objective of this study was to describe our experience developing a prostate HDR program, compare the LDR and HDR dosimetry, and identify the impact of several targeted interventions in the HDR workflow to improve efficiency. Methods and MaterialsWe performed a retrospective cohort study of patients treated with LDR or HDR prostate brachytherapy. We used iodine-125 seeds (145 Gy as monotherapy, and 110 Gy as a boost) and preoperative planning for LDR. For HDR, we used iridium-192 (13.5 Gy × 2 as monotherapy and 15 Gy × 1 as a boost) and computed tomography–based planning. Over the first 18 months, we implemented several targeted interventions into our HDR workflow to improve efficiency. To evaluate the progress of the HDR program, we used linear mixed-effects models to compare LDR and HDR dosimetry and identify changes in the implant procedure and treatment planning durations over time. ResultsThe study cohort consisted of 122 patients (51 who received LDR and 71 HDR). The mean D90 was similar between patients who received LDR and HDR (P = .28). HDR mean V100 and V95 were higher (P < .0001), but mean V200 and V150 were lower (P < .0001). HDR rectum V100 and D1cc were lower (P < .0001). The HDR mean for the implant procedure duration was shorter (54 vs 60 minutes; P = .02). The HDR mean for the treatment planning duration dramatically improved with the implementation of targeted workflow interventions (3.7 hours for the first quartile to 2.0 hours for the final quartile; P < .0001). ConclusionsWe successfully developed a prostate HDR brachytherapy program at our institution with comparable dosimetry to our historic LDR patients. We identified several targeted interventions that improved the efficiency of treatment planning. Our experience and workflow interventions may help other institutions develop similar HDR programs.

The Initial Single-Institution Experience of HDR Brachytherapy for the Treatment of Localized Prostate Cancer

Several effective treatment options for localized prostate cancer currently exist, including prostatectomy, external beam radiation, brachytherapy, or combined external beam radiation and brachytherapy, with or without androgen deprivation. Brachytherapy can deliver higher dose radiation to the target while limiting doses to adjacent normal structures. There is growing evidence supporting the efficacy and safety of HDR brachytherapy as a boost or monotherapy in prostate cancer treatment. We introduced an HDR prostate brachytherapy program in April 2014 as a treatment option for men with localized prostate cancer. Here we report this program’s outcome and toxicity results.

Learning Curve for Implementation of a High Dose-Rate Prostate Brachytherapy Program

Learning Curve for Implementation of a High Dose-Rate Prostate Brachytherapy Program

The American College of Radiology and the American Brachytherapy Society practice parameter for transperineal permanent brachytherapy of prostate cancer

Transperineal permanent brachytherapy is a safe and effective treatment option for patients with organ-confined prostate cancer. Careful adherence to established brachytherapy standards has been shown to improve the likelihood of procedural success and reduce the incidence of treatment-related morbidity. A collaborative effort of the American College of Radiology (ACR) and the American Brachytherapy Society (ABS) has produced practice parameters for LDR prostate brachytherapy. These practice parameters define the qualifications and responsibilities of all the involved personnel, including the radiation oncologist, physicist and dosimetrist. Factors with respect to patient selection and appropriate use of supplemental treatment modalities such as external beam radiation and androgen suppression therapy are discussed. Logistics with respect to the brachytherapy implant procedure, the importance of dosimetric guidelines, and attention to radiation safety procedures and documentation are presented. Adherence to these parameters can be part of ensuring quality and safety in a successful prostate brachytherapy program.

Implementation of Process Mapping to Improve a Clinical Workflow: A Study with Our Low Dose Rate Prostate Brachytherapy Program

Implementation of Process Mapping to Improve a Clinical Workflow: A Study with Our Low Dose Rate Prostate Brachytherapy Program

A sector-based postimplant dosimetric comparison of sagittal and axial ultrasound-guided source placement during I-125 permanent prostate brachytherapy.

262 Background: To use sector based pre- and postimplant dosimetric analysis to evaluate the effect of changes in implant technique in a developing I-125 permanent prostate brachytherapy program (PPB). Methods: 109 men treated with PPB were divided into two groups by implant technique. The first 50 patients (group 1) had needle-by-needle seed deposition under axial ultrasound (USS) guidance and subsequent 59 patients (group 2) having needle placement row-by-row then seed deposition under sagittal USS guidance. Twelve sector dose volume analysis of pre-implant ultrasound (USpre) and postimplant CT (CTpost) study was performed in all cases. Individual sectors were created by dividing the cranio-caudal prostate into three equal lengths creating prostate base, midgland and apex. Each of these volumes was then divided into four axial sectors (right and left anterior, right and left posterior). The difference in the minimum dose delivered to 90% of prostate volume (D90) and the prostate volume receiving 100%, 150%, and 200% of the prescribed dose (V100, V150, and V200) was compared between both groups. Results: In both groups, the volume of prostate in sectors one through six (entire base and anterior midgland) were significantly larger on CTpost when compared to equivalent sectors in USpre (p &lt; 0.001), conversely the volumes in sectors 11 and 12 (posterior apex) were significantly smaller (p =0.001). When comparing dosimetric parameters of all equivalent sectors in CTpost of both groups, it was found that D90 of sector seven and eight (posterior midgland) in Group 1 received increased dose leading to elevated dose to the rectum but was significantly reduced in Group 2 (p &lt; 0.01), which resulted in achieving the dose as planned in USpre. Prostate implant dosimetry was significantly improved in group 2 with a trend to increased equivalent dose between CTpost and USpre to each sectors and significant decrease in V150 and V200 in majority of the sectors. Conclusions: The row-by-row technique under sagittal USS guidance significantly improved our post implant dosimetric parameters when compared to single needle source placement under axial USS guidance as assessed by 12 sector analysis.

Decline in acute urinary toxicity: A long-term study in 2011 patients with prostate brachytherapy within a provincial institution

To determine whether acute urinary toxicity rates improve with the overall experience of a large prostate brachytherapy program. From 1998 to 2009, 2937 patients were treated with prostate brachytherapy at the British Columbia Cancer Agency. Baseline patient, treatment, and implant factors were recorded prospectively. Acute urinary toxicity data were prospectively recorded at baseline and each follow-up visit. Patients with ≥2 years of follow-up data were grouped into cohorts of 500 for analysis. Two thousand eleven patients met the above criteria. Acute urinary retention (AUR) in the acute period (within 6 months of implant) occurred in 9.1% of patients overall and was prolonged (catheterization >20 days) in 3.4%. Both overall AUR and prolonged AUR decreased across implant cohorts (p ≤ 0.001 in both cases). Overall acute Radiation Therapy Oncology Group (RTOG) Grades 0 and 1 urinary toxicity rate was 57.5% and RTOG Grades 2 and 3 urinary toxicity rates were 34.3% and 8.1%, respectively. Acute toxicity improved over time for both RTOG Grades ≥2 and ≥3 toxicity (p < 0.0001). International prostate symptom score resolution to baseline was achieved in 80.5% of patients with a median time of 12.2 months. Acute AUR and RTOG urinary toxicity rates continue to decline with the increasing experience of our provincial prostate brachytherapy program, despite its expansion to new centers and addition of members. This is likely due to better patient selection, refinement in treatment planning and implantation technique, and mentorship and training process.

Radiation oncology and medical physicists quality assurance in British Columbia Cancer Agency Provincial Prostate Brachytherapy Program

To describe in detail British Columbia (BC) Cancer Agency (BCCA) Provincial Prostate Brachytherapy (PB) Quality Assurance (QA) Program. The BCCA PB Program was established in 1997. It operates as one system, unified and supported by electronic and information systems, making it a single PB treatment provider for province of BC and Yukon. To date, >4000 patients have received PB (450 implants in 2011), making it the largest program in Canada. The Program maintains a large provincial prospective electronic database with records on all patients, including disease characteristics, risk stratification, pathology, preplan and postimplant dosimetric data, follow-up of prostate-specific antigen, and toxicity outcomes. QA was an integral part of the program since its inception. A formal QA Program was established in 2002, with key components that include: unified eligibility criteria and planning system, comprehensive database, physics and oncologist training and mentorship programs, peer review process, individual performance outcomes and feedback process, structured continuing education and routine assessment of the program's dosimetry, toxicity and prostate-specific antigen outcomes, administration and program leadership that promotes a strong culture of patient safety. The emphasis on creating a robust, broad-based network of skilled providers has been achieved by the program's requirements for training, education, and the QA process. The formal QA process is considered a key factor for the success of cancer control outcomes achieved at BCCA. Although this QA model may not be wholly transferable to all PB programs, some of its key components may be applicable to other programs to ensure quality in PB and patient safety.

TH-A-BRB-01: Low Dose Rate Prostate Brachytherapy Quality Assurance and Treatment Evaluation

Most medical events in prostate seed brachytherapy may be attributed to physician or physicist error, but human failures resulting in patient harm often can be attributed to inadequate mechanisms to prevent failures from propagating to the patient. Quality assurance (QA) of permanent seed brachytherapy is particularly important because this modality, unique to radiotherapy, leaves a permanent record of the implant quality within the patient. This symposium aims to review the properties of permanent LDR brachytherapy that have made it so successful and the challenges that have prevented the full realization of its theoretical advantages. The temporal interplay between radioactive decay, resolution rate of procedure‐induced edema, and cellular processes will be discussed along with their effect on the design and evaluation of LDR prostate brachytherapy. Recent recommendations of AAPM TG‐137 on prostate brachytherapytreatment planning and dose reporting will be reviewed. An analysis of actual medical events and typical errors, for example seed strength in the plan versus the strength ordered versus the strength implanted, will help focus on critical components of the process map. A methodology to score failure modes and effects via the product of Likelihood × Severity × Undetectability will allow users to score procedural steps dynamically. Quality control steps such as second checks or calibrations will be seen as vital in keeping the scores below a level of concern. Finally, the physicist has a responsibility to offer suggestions to improve dosimetry when systematic trends are evident and to identify and report errors. Learning objectives: 1. Discuss recent developments and insights in LDR prostate brachytherapy 2. Identify critical physics components and their impact on QA and treatment evaluation 3. Highlight factors that require special attention in the planning and execution of implants 4. Demonstrate implementation of QA practices in an LDR prostate brachytherapy program

Radiation Oncologists Quality Assurance Program in British Columbia Cancer Agency Provincial Prostate Brachytherapy Program

Purpose: To describe system of novel quality assurance implemented after ABS 2010 in a large multicenter Provincial British Columbia Cancer Agency (BCCA) Prostate Brachytherapy Program with 14 practicing oncologist in 4 regional cancer centers.

The Dosimetric Impact of Supplementing Pre-Planned Prostate Implants With Discretionary 125I Seeds

Purpose: The British Columbia Cancer Agency (BCCA) Provincial Prostate Brachytherapy program was established in 1998. Over 3000 implants have been done to date. Implants are performed using a pre-planned, real time ultrasound-guided transperineal technique, with stranded seeds and modified peripheral loading to deliver an mPD of 144 Gy to the prostate plus margins. For each implant, 5 extra seeds (2 stranded and 3 loose) are provided to be used at the discretion of the physician. The aim of this research was to investigate the dosimetric impact of these extra seeds, and the circumstances under which they are most commonly used. Materials and Methods: Post-implant questionnaires were completed by 5 experienced physicians to prospectively collect information on 70 consecutive implants performed over a 4 month period. After each implant, the location and rationale for using any extra seeds was recorded by each physician. All study patients underwent day-0 post implant dosimetry. A previously developed plan reconstruction algorithm was used to distinguish the extra seeds from those which were planned. The dose distributions with and without the extra seeds were compared for the whole prostate, anterior-superior (ASQ), anterior-inferior (AIQ), posterior-superior (PSQ), and posterior-inferior (PIQ) prostate quadrants, urethra and rectum. The Conformity Index (CI) and External Index (EI) were computed to assess collateral dose outside the target. Results: Extra seeds were used in 83% of the cohort with a median of 5 extra seeds/implant. The majority of the extra seeds were deposited in the ASQ (64%) and less frequently in other quadrants; PSQ (24%), AIQ (7%) and PIQ (5%). The most commonly reported reasons for the use of extra seeds was to improve coverage of the anterior base (42% of responses), and target regions of biopsy confirmed cancer (26%). The use of extra seeds resulted in a mean increase in whole prostate V100, V150 and V200 of 3.7% (mean V100 90.5% to 93.8%), 13% (mean V150 45% to 50.6%) and 19% (mean V200 13.5% to 16%), respectively. Mean whole prostate D90 increased from 147Gy to 156Gy. The use of extra seeds increased V100 over the 90% threshold in 15 (26%) patients. Five patients (9%) who received dose supplementation would otherwise have been classified as having suboptimal coverage (mean V100 of 83.2% improved to 91.1% after using extra seeds). Quadrant analysis demonstrated that extra seeds had the most impact on ASQ coverage, in line with the stated goals of their use, with a mean V100 increase of 13.6% (mean V100 74% to 83%) and a mean D90 increase of 9.1% (mean D90 123Gy to 134Gy). Extra seeds increased the rectal dose (VR100) by a mean of 5.9% (mean VR100 0.543 cc to 0.579cc). The mean urethral dose increased from 134.8Gy to 140.6Gy with a mean increase of 4.5% (range 1.16Gy to 5.8 Gy). The CI increased from a mean of 1.89 to 1.92 while the mean EI increased from 0.809 to 0.869. Conclusions: Bolstering coverage of the anterior prostate base is the main reason extra seeds were used in this cohort, and this aim was consistently achieved with only minor impact on the urethral, rectal and extra-prostatic tissues. However, there was a considerable increase in prostate V150 and V200. The accuracy with which dose was boosted in the biopsy positive regions is under investigation.

Estimating Seed Orientation in Strands for Anisotropy Sensitive Post-implant Dosimetry of the Prostate

Purpose:TheBritishColumbiaCancerAgency (BCCA) Provincial Prostate Brachytherapy program was established in 1998. Over 3000 implants have been done to date. Implants are performed using a pre-planned, real time ultrasound-guided transperineal technique, with stranded seeds and modified peripheral loading to deliver an mPD of 144 Gy to the prostate plus margins. For each implant, 5 extra seeds (2 stranded and 3 loose) are provided to be used at the discretion of the physician. The aim of this research was to investigate the dosimetric impact of these extra seeds, and the circumstances under which they are most commonly used. Materials and Methods: Post-implant questionnaires were completed by 5 experienced physicians to prospectively collect information on 70 consecutive implants performed over a 4 month period. After each implant, the location and rationale for using any extra seeds was recorded by each physician. All study patients underwent day-0 post implant dosimetry. A previously developed plan reconstruction algorithm was used to distinguish the extra seeds from those which were planned. The dose distributions with and without the extra seeds were compared for the whole prostate, anterior-superior (ASQ), anterior-inferior (AIQ), posteriorsuperior (PSQ), and posterior-inferior (PIQ) prostate quadrants, urethra and rectum. The Conformity Index (CI) and External Index (EI) were computed to assess collateral dose outside the target. Results:Extra seeds were used in 83%of the cohort with amedian of 5 extra seeds/implant. The majority of the extra seeds were deposited in the ASQ (64%) and less frequently in other quadrants; PSQ (24%), AIQ (7%) and PIQ (5%). The most commonly reported reasons for the use of extra seeds was to improve coverage of the anterior base (42% of responses), and target regions of biopsy confirmed cancer (26%). The use of extra seeds resulted in a mean increase in whole prostate V100, V150 and V200 of 3.7% (mean V100 90.5% to 93.8%), 13% (mean V150 45% to 50.6%) and 19% (mean V200 13.5% to 16%), respectively. Mean whole prostate D90 increased from 147Gy to 156Gy. The use of extra seeds increased V100 over the 90% threshold in 15 (26%) patients. Five patients (9%) who received dose supplementation would otherwise have been classified as having suboptimal coverage (mean V100 of 83.2% improved to 91.1% after using extra seeds). Quadrant analysis demonstrated that extra seeds had the most impact on ASQ coverage, in line with the stated goals of their use, with a mean V100 increase of 13.6% (mean V100 74% to 83%) and a mean D90 increase of 9.1% (mean D90 123Gy to 134Gy). Extra seeds increased the rectal dose (VR100) by a mean of 5.9% (mean VR100 0.543 cc to 0.579cc). The mean urethral dose increased from 134.8Gy to 140.6Gy with a mean increase of 4.5% (range 1.16Gy to 5.8 Gy). The CI increased from a mean of 1.89 to 1.92 while the mean EI increased from 0.809 to 0.869. Conclusions: Bolstering coverage of the anterior prostate base is the main reason extra seeds were used in this cohort, and this aim was consistently achieved with only minor impact on the urethral, rectal and extraprostatic tissues. However, there was a considerable increase in prostate V150 and V200. The accuracy with which dose was boosted in the biopsy positive regions is under investigation.

American Society for Radiation Oncology (ASTRO) and American College of Radiology (ACR) Practice Guideline for the Transperineal Permanent Brachytherapy of Prostate Cancer

Transperineal permanent prostate brachytherapy is a safe and efficacious treatment option for patients with organ-confined prostate cancer. Careful adherence to established brachytherapy standards has been shown to improve the likelihood of procedural success and reduce the incidence of treatment-related morbidity. A collaborative effort of the American College of Radiology (ACR) and American Society for Therapeutic Radiation Oncology (ASTRO) has produced a practice guideline for permanent prostate brachytherapy. The guideline defines the qualifications and responsibilities of all the involved personnel, including the radiation oncologist, physicist and dosimetrist. Factors with respect to patient selection and appropriate use of supplemental treatment modalities such as external beam radiation and androgen suppression therapy are discussed. Logistics with respect to the brachytherapy implant procedure, the importance of dosimetric parameters, and attention to radiation safety procedures and documentation are presented. Adherence to these practice guidelines can be part of ensuring quality and safety in a successful prostate brachytherapy program.

The dosimetric quality of brachytherapy implants in patients with small prostate volume depends on the experience of the brachytherapy team

Purpose To investigate the dosimetric outcome of brachytherapy in patients with small prostate volume (PV). Methods and Materials Forty-three patients with small PV (<25 cm 3) as determined using transrectal ultrasound and 120 patients with non–small PV (>25 cm 3) that had received 125I seed implants were reviewed in a retrospective cohort study. Implantations were performed under transrectal ultrasound guidance, and the prescription dose was 145 Gy. A CT and MRI scan of the pelvis were performed 1 month after implantation for dosimetric study. Results Compared with non–small PV patients, patients with small PV experienced larger 1-month edema ( p < 0.001); lower dose to 90% (the isodose enclosing 90% of PV and representing a minimum dose to that volume of the prostate [ D 90]) of the prostate ( p = 0.03); higher intracapsular seed density ( p < 0.001); and were less likely to achieve D 90 ≥ 140 Gy ( p = 0.013) in a postimplant dosimetric study. The number of patients with D 90 < 140 Gy decreased steadily in both subsets of patients as the implant program matured (odds ratio = 0.56 per year, p < 0.001), but the small prostate group exhibited more improvement compared with the non–small prostate patients over the same time period. Multivariate analysis revealed that brachytherapy team experience rather than the size of prostate was a more important predictive factor of implant quality ( p < 0.001). Conclusions This single institution experience demonstrated a significant learning curve in the initial years of a prostate brachytherapy program, especially for patients with small prostates. A small prostate itself is not a contraindication of brachytherapy. The quality of implant for patients with small prostates depends more on the skill of the brachytherapy team.

2056 Fundamental study of polaprezinc suppositories in the prevention of acute radiation proctitis in rats

To investigate the dosimetric outcome of brachytherapy in patients with small prostate volume (PV).Forty-three patients with small PV (<25 cm3) as determined using transrectal ultrasound and 120 patients with non–small PV (>25 cm3) that had received 125I seed implants were reviewed in a retrospective cohort study. Implantations were performed under transrectal ultrasound guidance, and the prescription dose was 145 Gy. A CT and MRI scan of the pelvis were performed 1 month after implantation for dosimetric study.Compared with non–small PV patients, patients with small PV experienced larger 1-month edema (p < 0.001); lower dose to 90% (the isodose enclosing 90% of PV and representing a minimum dose to that volume of the prostate [D90]) of the prostate (p = 0.03); higher intracapsular seed density (p < 0.001); and were less likely to achieve D90 ≥ 140 Gy (p = 0.013) in a postimplant dosimetric study. The number of patients with D90 < 140 Gy decreased steadily in both subsets of patients as the implant program matured (odds ratio = 0.56 per year, p < 0.001), but the small prostate group exhibited more improvement compared with the non–small prostate patients over the same time period. Multivariate analysis revealed that brachytherapy team experience rather than the size of prostate was a more important predictive factor of implant quality (p < 0.001).This single institution experience demonstrated a significant learning curve in the initial years of a prostate brachytherapy program, especially for patients with small prostates. A small prostate itself is not a contraindication of brachytherapy. The quality of implant for patients with small prostates depends more on the skill of the brachytherapy team.

SU‐FF‐T‐67: Implementation of the TG‐128 Recommendations for Quality Assurance of Prostate Brachytherapy Ultrasound Systems

Purpose: The purpose of this work is to assess several aspects of the implementation of the recommended TG‐128 quality assurance tests, including the time to perform the tests, the general range of parameters for several ultrasound systems, and correlation of QA components with treatment technique. Method and Materials: The TG‐128 tests were performed on a selection of ultrasound units and biplane transducers commonly used in prostate brachytherapy. The author used the following ancillary equipment to conduct the tests: the CIRS Model‐45 Prostate Brachytherapy Phantom, a container of distilled water, brachytherapy needles, a needle template, a stepper/stabilizer for the probe, and a computerized treatment planning system. Each test was independently timed and notes were made of any deviations in terms of equipment limitations and expected results. Results: The typical time to complete all required tests was approximately ninety minutes. Once the user establishes baseline data and develops a system for conducting the tests, this duration can readily be shortened to one hour. The measurements generally fell well within the tolerances recommended in TG‐128 with the exception of needle template/electronic grid alignment (Test 7), where discrepancies approached the action level of 3 mm and the tissue/water correction factor was important. Care must be exercised in performing the volume measurements, as it can be difficult (a) to get acoustic coupling across the angle subtended by the target to be measured, and (b) to move the probe longitudinally without losing coupling. Based on the experience gained performing these tests, a standard form has been developed for recording the results. Conclusion: The quality assurance tests recommended by TG‐128 for prostate brachytherapy ultrasound systems can be completed in a reasonable amount of time. Consideration must be given by the user as to how these tests relate to the overall quality assurance of the prostate brachytherapy program.

Enhanced efficiency and ergonomics of an intraoperative automated prostate brachytherapy delivery technique

Introduction In 2003, the Tom Baker Cancer Centre started a prostate brachytherapy program using Iodine-125 seeds, intraoperative treatment planning, and an automated remote afterloader, the seedSelectron. Over a 3-month period in 2004–2005, technologic changes were implemented with the intent of reducing the time spent in the operating room and improving ergonomics for the radiation oncologist/surgeon. New commercial software including inverse planning was installed, concurrent needle insertion and seed train building was implemented, and additional hardware (a slave monitor) was connected to the system. Purpose To demonstrate that, with these enhancements, dosimetry is not compromised, whereas efficiency is significantly improved. Methods Interactive inverse planning was used to create the treatment plans in the operating room. Seed-spacer trains were built concurrently with each needle's insertion guided by rotating the ultrasound probe to the correct sagittal plane using the Needle Navigator feature. Needles were built, inserted, and delivered one needle at a time. Needle coordinate and insert positions were verified on the live ultrasound image displayed on both the slave monitor positioned above the patient's pelvis and the operator console. Dosimetry parameters ( D 90 and V 100), numbers of seeds, and OR times were compared for 20 patients before and 11 patients after the implementation of the concurrent insertion and build protocol combined with inverse planning and the slave monitor. Results Operating room (OR) times (probe in to probe out) were reduced by 33 min and the number of seeds per unit volume by 3% on an average. The majority of the decrease in time is due to the concurrent building and insertion of needles. Before and after the new technique, average postplan D 90 and V 100 values at 4 weeks after the implant were the same to within 4 Gy and 0.1%, respectively. The range (max–min) of D 90 decreased by 20% of the mean dose and the V 100 range decreased by 6% with the new technique. Adding the slave monitor improved quality assurance of the delivery process and ergonomics for physicians. Conclusions The concurrent insertion and build protocol, together with inverse planning and the slave monitor, have decreased OR times with greater consistency in the delivered dose distribution.