Rapid multi-catheter segmentation for magnetic resonance image-guided catheter-based interventions.

BACKGROUND: Magnetic resonance imaging (MRI) is the gold standard for delineating cancerous lesions in soft tissue. Catheter-based interventions require the accurate placement of multiple long, flexible catheters at the target site. The manual segmentation of catheters in MR images is a challenging and time-consuming task. There is a need for automated catheter segmentation to improve the efficiency of MR-guided procedures. PURPOSE: To develop and assess a machine learning algorithm for the detection of multiple catheters in magnetic resonance images used during catheter-based interventions. METHODS: In this work, a 3D U-Net was trained to retrospectively segment catheters in scans acquired during clinical MR-guided high dose rate (HDR) prostate brachytherapy cases. To assess confidence in segmentation, multiple AI models were trained. On clinical test cases, average segmentation results were used to plan the brachytherapy delivery. Dosimetric parameters were compared to the original clinical plan. Data was obtained from 35 patients who underwent HDR prostate brachytherapy for focal disease with a total of 214 image volumes. 185 image volumes from 30 patients were used for training using a five-fold cross validation split to divide the data for training and validation. To generate confidence measures of segmentation accuracy, five trained models were generated. The remaining five patients (29 volumes) were used to test the performance of the trained model by comparison to manual segmentations of three independent observers and assessment of dosimetric impact on the final clinical brachytherapy plans. RESULTS: The network successfully identified 95% of catheters in the test set at a rate of 0.89 s per volume. The multi-model method identified the small number of cases where AI segmentation of individual catheters was poor, flagging the need for user input. AI-based segmentation performed as well as segmentations by independent observers. Plan dosimetry using AI-segmented catheters was comparable to the original plan. CONCLUSION: The vast majority of catheters were accurately identified by AI segmentation, with minimal impact on plan outcomes. The use of multiple AI models provided confidence in the segmentation accuracy and identified catheter segmentations that required further manual assessment. Real-time AI catheter segmentation can be used during MR-guided insertions to assess deflections and for rapid planning of prostate brachytherapy.

Comparing dosimetry of locally advanced cervical cancer patients treated with 3 versus 4 fractions of MRI-guided brachytherapy.

PURPOSE: To demonstrate the feasibility of treating cervical cancer patients with MRI-guided brachytherapy (MRgBT) using 24 Gy in 3 fractions (F) versus a standard, more resource-intensive regimen of 28 Gy in 4F, and its ability to meet EMBRACE II planning aims. METHODS AND MATERIALS: A retrospective review of 224 patients with FIGO Stage IB-IVA cervical cancer treated with 28 Gy/4F (n = 91) and 24 Gy/3F (n = 133) MRgBT between 2016-2021 was conducted. Multivariable linear regression models were fitted to compare dosimetric parameters between the two groups, adjusting for CTVHR and T stage. RESULTS: Most patients had squamous cell carcinoma, T2b disease, and were treated with intracavitary applicator plus interstitial needles (96%). The 28 Gy/4F group had higher CTVHR (median 28 vs. 26 cm3, p = 0.04), CTVIR D98% (mean 65.5 vs. 64.5 Gy, p = 0.03), rectum D2cm3 (mean 61.7 vs. 59.2 Gy, p = 0.04) and bladder D2cm3 (81.3 vs. 77.9 Gy, p = 0.03). There were no significant differences in the proportion of patients meeting the EMBRACE II OAR dose constraints and planning aims, except fewer patients treated with 28 Gy/4F met rectum D2cm3 < 65 Gy (73 vs. 85%, p = 0.027) and ICRU rectovaginal point < 65 Gy (65 vs. 84%, p = 0.005). CONCLUSIONS: Cervical cancer patients treated with 24 Gy/3F MRgBT had comparable target doses and lower OAR doses compared to those treated with 28 Gy/4F. A less-resource intense fractionation schedule of 24 Gy/3F is an alternative to 28 Gy/4F in cervix MRgBT.

Acute toxicity and health-related quality of life outcomes of localized prostate cancer patients treated with magnetic resonance imaging-guided high-dose-rate brachytherapy: A prospective phase II trial.

PURPOSE: To report acute toxicity and health-related quality of life (HRQoL) outcomes of a phase II clinical trial of magnetic resonance imaging (MRI)-guided prostate high-dose-rate brachytherapy (HDR-BT) combined with external beam radiotherapy. METHODS AND MATERIALS: Patients with intermediate- and high-risk prostate cancer (PCa) were eligible. Treatment consisted of a single 15 Gy MRI-guided HDR-BT followed by external beam radiotherapy (37.5-46 Gy depending on their risk category). Dosimetry, toxicity and HRQoL outcomes were collected prospectively at baseline, 1 and 3 months using Common Terminology Criteria for Adverse Events Version 4.0 and the expanded PCa index composite, respectively. General linear mixed modeling was conducted to assess the changes in expanded PCa index composite domain scores over time. A minimally important difference was defined as a deterioration of HRQoL scores at 3 months compared to baseline ≥ 0.5 standard deviation. A p value ≤ 0.05 was considered statistically significant. RESULTS: Sixty-one patients were included. Acute grade (G)2 urinary toxicity was observed in 18 (30%) patients while 1 (2%) patient had G3 toxicity, and none had G4 toxicity. Two patients had an acute urinary retention. G2 gastrointestinal toxicity was reported by 5 (8%) patients with no G3-4. Compared to baseline, urinary HRQoL scores significantly declined at 1 month (p < 0.001) but recovered at 3 months (p > 0.05). Bowel (p < 0.001) and sexual (p < 0.001) domain scores showed a significant decline over the 3-month follow-up period. At 3 months, 44%, 49% and 57% of patients reported a minimally important difference respectively in the urinary bowel and sexual domains. CONCLUSION: MRI-guided HDR-BT boost is a safe and well tolerated treatment of intermediate- and high-risk PCa in the acute setting. A longer follow-up and a comparison to ultrasound-based HDR-BT are needed to assess the potential benefit of MRI-guided prostate HDR-BT.

Feasibility study of navigated endoscopy for the placement of high dose rate brachytherapy applicators in the esophagus and lung.

PURPOSE: To evaluate the electromagnetic (EM) tracking of endoscopes and applicators as a method of positioning a high dose rate (HDR) luminal applicator. METHOD: An anatomical phantom consisting of a rigid trachea and flexible esophagus was used to compare applicator placement measurements using EM tracking vs the traditional method using two-dimensional (2D) fluoroscopy and surface skin markers. The phantom included a tumor in the esophagus and several pairs of optically visible points inside the lumen that were used to simulate proximal and distal ends of tumors of varying lengths. The esophagus tumor and lung points were visible on a computed tomography (CT) image of the phantom, which was used as ground truth for the measurements. The EM tracking system was registered to the CT image using fiducial markers. A flexible endoscope was tracked using the EM system and the locations of the proximal and distal ends of the tumor identified and this position recorded. An EM-tracked applicator was then inserted and positioned relative to the tumor markings. The applicator path was mapped using the EM tracking. The gross tumor length (GTL) and the distance between the first dwell position and distal edge of tumor (offset) were measured using the EM tracking and 2D fluoroscopy methods and compared to the same measurements on the CT image. RESULTS: The errors in GTL using EM tracking were on average -0.5 ± 1.7 mm and 0.7 ± 3.6 mm for esophagus and lung measurements, similar to errors measured using the 2D fluoroscopy method of -0.9 ± 1.2 mm and 3.4 ± 4.4 mm. Offset measurements were slightly larger while using EM tracking relative to the fluoroscopy method but these were not statistically significant. CONCLUSIONS: Electromagnetic tracking for placement of lumen applicators is feasible and accurate. Tracking of the endoscope that is used to identify the proximal and distal ends of the tumor and of the applicator during insertion generates accurate three-dimensional measurements of the applicator path, GTL and offset. Guiding the placement of intraluminal applicators using EM navigation is potentially attractive for cases with complex insertions, such as those with nonlinear paths or multiple applicator insertions.

Dose to the bladder neck in MRI-guided high-dose-rate prostate brachytherapy: Impact on acute urinary toxicity and health-related quality of life.

PURPOSE: To assess the impact of the dose to the bladder neck (BN) on acute urinary toxicity (AUT) and health-related quality of life (uHRQoL) in patients with prostate cancer treated with MRI-guided high-dose-rate brachytherapy combined to external beam radiotherapy. METHODS AND MATERIALS: Sixty-one patients were treated with a single 15-Gy MRI-guided high-dose-rate brachytherapy followed by external beam radiotherapy as part of a prospective Phase II trial. The BN was delineated in retrospect on T2-weighted images. AUT and uHRQoL data were collected prospectively using Common Terminology Criteria for Adverse Events version 4.0 and the expanded prostate index composite. A minimally important difference (MID) was defined as a deterioration of uHRQoL scores at 3 months ≥ 0.5 standard deviation of baseline score. Linear and logistic regression models were used. RESULTS: The median BN volume was 0.6 cc. The median BN and urethral maximum dose (BNDmax and UDmax) were 22 Gy and 20 Gy, respectively. BNDmax was significantly associated with UDmax (p = 0.03). AUT Grade 2 + was observed in 32% of patients. Among those, 4 patients had an acute urinary retention (AUR). No Grade 4 + toxicity was reported. At 3 months, 47% of patients reported an MID in urinary uHRQoL. None of the dosimetric parameters including BNDmax was associated with acute Grade 2 + urinary toxicity or MID. However, 3 of 4 patients with AUR had a BNDmax in the highest quartile; >175% of prescription dose. CONCLUSIONS: Although a high BN dose was observed in patients who had an AUR, the predictive value of this parameter is yet to be determined in a larger cohort.

Comparison of dosimetric parameters derived from whole organ and wall contours for bladder and rectum in cervical cancer patients treated with intracavitary and interstitial brachytherapy.

For volumes up to 2 cm3 of the bladder and possibly up to 5 cm3 of the rectum, doses computed from the whole organ were good estimates of the doses in the wall in cervix brachytherapy, and there were no significant differences between patients treated with or without interstitial needles.

Technique adaptation, strategic replanning, and team learning during implementation of MR-guided brachytherapy for cervical cancer.

PURPOSE: MR-guided brachytherapy (MRgBT) with interstitial needles is associated with improved outcomes in cervical cancer patients. However, there are implementation barriers, including magnetic resonance (MR) access, practitioner familiarity/comfort, and efficiency. This study explores a graded MRgBT implementation strategy that included the adaptive use of needles, strategic use of MR imaging/planning, and team learning. METHODS AND MATERIALS: Twenty patients with cervical cancer were treated with high-dose-rate MRgBT (28 Gy in four fractions, two insertions, daily MR imaging/planning). A tandem/ring applicator alone was used for the first insertion in most patients. Needles were added for the second insertion based on evaluation of the initial dosimetry. An interdisciplinary expert team reviewed and discussed the MR images and treatment plans. RESULTS: Dosimetry-trigger technique adaptation with the addition of needles for the second insertion improved target coverage in all patients with suboptimal dosimetry initially without compromising organ-at-risk (OAR) sparing. Target and OAR planning objectives were achieved in most patients. There were small or no systematic differences in tumor or OAR dosimetry between imaging/planning once per insertion vs. daily and only small random variations. Peer review and discussion of images, contours, and plans promoted learning and process development. CONCLUSIONS: Technique adaptation based on the initial dosimetry is an efficient approach to implementing MRgBT while gaining comfort with the use of needles. MR imaging and planning once per insertion is safe in most patients as long as applicator shifts, and large anatomical changes are excluded. Team learning is essential to building individual and programmatic competencies.

Dosimetric impact of intrafraction changes in MR-guided high-dose-rate (HDR) brachytherapy for prostate cancer.

PURPOSE: To assess changes in implant and treatment volumes through the course of a prostate high-dose-rate brachytherapy procedure and their impact on plan quality metrics. METHODS AND MATERIALS: Sixteen MRI-guided high-dose-rate procedures included a post-treatment MR (ptMR) immediately after treatment delivery (135 min between MR scans). Target and organs at risk (OARs) were contoured, and catheters were reconstructed. The delivered treatment plan was applied to the ptMR image set. Volumes and dosimetric parameters in the ptMR were evaluated and compared with the delivered plan using a paired two-tailed t-test with p < 0.05 considered statistically significant. RESULTS: An average increase of 8.9% in prostate volume was observed for whole-gland treatments, resulting in reduction in coverage for both prostate and planning target volume, reflected in decreased V100 (mean 3.3% and 4.6%, respectively, p < 0.05), and D90 (mean 7.1% and 7.6%, respectively, of prescription dose, p < 0.05). There was no significant change in doses to OARs. For partial-gland treatments, there was an increase in planning target volume (9.1%), resulting in reduced coverage and D90 (mean 3.6% and 12.4%, respectively, p < 0.05). A decrease in D0.5cc for bladder (3%, p < 0.05) was observed, with no significant changes in dose to other OARs. CONCLUSIONS: Volumetric changes were observed during the time between planning MR and ptMR. Nonetheless, treatment plans for both whole- and partial-gland therapies remained clinically acceptable. These results apply to clinical settings in which patients remain in the same position and under anesthesia during the entire treatment process.

Brachytherapy patient safety events in an academic radiation medicine program.

PURPOSE: To describe the incidence and type of brachytherapy patient safety events over 10 years in an academic brachytherapy program. METHODS AND MATERIALS: Brachytherapy patient safety events reported between January 2007 and August 2016 were retrieved from the incident reporting system and reclassified using the recently developed National System for Incident Reporting in Radiation Treatment taxonomy. A multi-incident analysis was conducted to identify common themes and key learning points. RESULTS: During the study period, 3095 patients received 4967 brachytherapy fractions. An additional 179 patients had MR-guided prostate biopsies without treatment as part of an interventional research program. A total of 94 brachytherapy- or biopsy-related safety events (incidents, near misses, or programmatic hazards) were identified, corresponding to a rate of 2.8% of brachytherapy patients, 1.7% of brachytherapy fractions, and 3.4% of patients undergoing MR-guided prostate biopsy. Fifty-one (54%) events were classified as actual incidents, 29 (31%) as near misses, and 14 (15%) as programmatic hazards. Two events were associated with moderate acute medical harm or dosimetric severity, and two were associated with high dosimetric severity. Multi-incident analysis identified five high-risk activities or clinical scenarios as follows: (1) uncommon, low-volume or newly implemented brachytherapy procedures, (2) real-time MR-guided brachytherapy or biopsy procedures, (3) use of in-house devices or software, (4) manual data entry, and (5) patient scheduling and handoffs. CONCLUSIONS: Brachytherapy is a safe treatment and associated with a low rate of patient safety events. Effective incident management is a key element of continuous quality improvement and patient safety in brachytherapy.

Evaluation of the dosimetric impact of loss and displacement of seeds in prostate low-dose-rate brachytherapy.

PURPOSE: To analyze the seed loss and displacement and their dosimetric impact in prostate low-dose-rate (LDR) brachytherapy while utilizing the combination of loose and stranded seeds. MATERIAL AND METHODS: Two hundred and seventeen prostate cancer patients have been treated with LDR brachytherapy. Loose seeds were implanted in the prostate center and stranded seeds in the periphery of the gland. Patients were imaged with transrectal ultrasound before implant and with computerized tomography/magnetic resonance imaging (CT/MR) one month after implant. The seed loss and displacement had been analyzed. Their impact on prostate dosimetry had been examined. The seed distribution beyond the prostate inferior boundary had been studied. RESULTS: The mean number of seeds per patient that were lost to lung, pelvis/abdomen, urine, or unknown destinations was 0.21, 0.13, 0.03, and 0.29, respectively. Overall, 40.1% of patients had seed loss. Seed migration to lung and pelvis/abdomen occurred in 15.5% and 10.5% of the patients, respectively. Documented seed loss to urine was found in 3% of the patients while 20% of patients had seed loss to unknown destinations. Prostate length difference between pre-plan and post-implant images was within 6 mm in more than 98% of cases. The difference in number of seeds inferior to prostate between pre-plan and post-implant dosimetry was within 7 seeds for 93% of patients. At time of implant, 98% of seeds, inferior to prostate, were within 5 mm and 100% within 15 mm, and in one month post-implant 83% within 9 mm and 96.3% within 15 mm. Prostate post-implant V100, D90, and rectal wall RV100 for patients without seed loss were 94.6%, 113.9%, and 0.98 cm(3), respectively, as compared to 95.0%, 114.8%, and 0.95 cm(3) for the group with seed loss. CONCLUSIONS: Seed loss and displacement have been observed to be frequent. No correlation between seed loss and displacement and post-plan dosimetry has been reported.

Dosimetric evaluation of clinical target volume in the postimplant analysis of low-dose-rate brachytherapy for prostate cancer.

PURPOSE: Brachytherapy is an effective single treatment modality for low- and intermediate-risk prostate cancer. In this study, we defined a clinical target volume (CTV) and evaluated its dosimetry 1 month after the low-dose-rate brachytherapy procedure. METHODS AND MATERIALS: One hundred ninety-eight consecutive patients treated for prostate cancer by iodine-125 seed brachytherapy were assessed. Prostate dosimetry was stratified according to British Columbia Cancer Agency criteria, with good implants having both V100 (percentage of target volume that receives 100% of the prescribed dose) > 85% and D90 (percentage of the prescribed dose received by 90% of the target volume) > 90%, suboptimal implants with V100 of 75-85%, or D90 80-90%, whereas poor implants were defined as those with V100 < 75 or D90 < 80%. CTV dosimetry stratification was performed according to the same dose coverage criteria, albeit to the CTV. RESULTS: One hundred ninety-two patients (97%) had good prostate radiation coverage, whereas only 165 patients (83%) had good postimplant CTV dosimetry. Patients with suboptimal vs. good CTV dosimetry had prostate edema of 7.8 ± 0.2% vs. 0.2 ± 0.1%, respectively (p = 0.001). CONCLUSIONS: Prostate seed implants with optimal dosimetry to prostate may still have suboptimal D90 and V100 for the CTV, especially in the presence of postimplant edema. A consensus is needed for definition and evaluation of CTV in postimplant setting for low-dose-rate prostate brachytherapy.

Sector analysis of dosimetry of prostate cancer patients treated with low-dose-rate brachytherapy.

PURPOSE: Brachytherapy is an effective single treatment modality for low- and intermediate-risk prostate cancer. Here, we compare the radiation doses in different prostate sectors between the preimplant planning images and the postimplant dosimetry. METHODS AND MATERIALS: Two hundred fifteen consecutive patients treated for prostate cancer by (125)I seed brachytherapy were assessed. Pretreatment plans using transrectal ultrasound images of the prostate were compared with the dose calculated on posttreatment MRI and CT scans obtained 1 month after seed implantation. Twelve sectors were generated by dividing the prostate base, midgland, and apex into four quadrants each. Pretreatment and posttreatment dosimetry were compared between the 12 different sectors of the prostate. RESULTS: Average V100 (percentage of prostate volume that receives 100% of the prescribed dose) in the preimplant planning images of the prostate was 99.9 ± 0.25% compared with postimplant V100 of 94.8 ± 3.77% (p < 0.0001). Prostate V100 in the postimplant dosimetry was >91% in all sectors, except the anterior base sector, in which it was 64.87 ± 20.96%. Average 1-month D90 (the dose to 90% of the prostate volume) was 114.5 ± 10.55%. D90 at 1 month compared with preimplant planning was lower in the prostate base and higher in the prostate apex (p < 0.001). CONCLUSIONS: Our results show that in (125)I seed brachytherapy, prostate base receives a lower dose and apex receives a higher dose compared with preimplant planned dose coverage.

10-year experience with I-125 prostate brachytherapy at the Princess Margaret Hospital: results for 1,100 patients.

PURPOSE: To report outcomes for 1,111 men treated with iodine-125 brachytherapy (BT) at a single institution. METHODS AND MATERIALS: A total of 1,111 men (median age, 63) were treated with iodine-125 prostate BT for low- or intermediate-risk prostate cancer between March 1999 and November 2008. Median prostate-specific antigen (PSA) level was 5.4 ng/ml (range, 0.9-26.1). T stage was T1c in 66% and T2 in 34% of patients. Gleason score was 6 in 90.1% and 7 or 8 in 9.9% of patients. Neoadjuvant hormonal therapy (2-6 months course) was used in 10.1% of patients and combined external radiotherapy (45 Gy) with BT (110 Gy) in 4.1% (n = 46) of patients. Univariate and multivariate Cox proportional hazards were used to determine predictors of failure. RESULTS: Median follow-up was 42 months (range, 6-114), but for biochemical freedom from relapse, a minimum PSA test follow-up of 30 months was required (median 54; n = 776). There were 27 failures, yielding an actuarial 7-year disease-free survival rate of 95.2% (96 at risk beyond 84 months). All failures underwent repeat 12-core transrectal ultrasound -guided biopsies, confirming 8 local failures. On multivariate analysis, Gleason score was the only independent predictor of failure (p = 0.001; hazard ratio, 4.8 (1.9-12.4). Median International Prostate Symptom score from 12 to 108 months ranged between 3 and 9. Of the men reporting baseline potency, 82.8% retained satisfactory erectile function beyond 5 years. CONCLUSION: Iodine-125 prostate BT is a highly effective treatment option for favorable- and intermediate-risk prostate cancer and is associated with maintenance of good urinary and erectile functions.

Biochemical disease-free rate and toxicity for men treated with iodine-125 prostate brachytherapy with d(90) ≥180 Gy.

PURPOSE: Iodine-125 ((125)I) prostate brachytherapy is planned with a prescribed dose of 145 Gy and minimal dose received by 90% of the prostate (D(90)) of 120-125% (174-181 Gy). We examined the clinical outcomes and toxicity profile of men receiving a D(90) (isodose enclosing 90% of the prostate) of ≥180 Gy. METHODS AND MATERIALS: Between March 1999 and May 2006, 129 men (17% of our total brachytherapy population) treated with (125)I monotherapy for Stage T1-T2 prostate cancer received a D(90) ≥180 Gy. Implants were performed using transrectal ultrasonography and fluoroscopic guidance. The 1-month postplan dosimetry used magnetic resonance imaging-computed tomography fusion. The minimal follow-up was 2 years. Toxicity was scored according to the National Cancer Institute Common Terminology Criteria for Adverse Events toxicity scale, version 3. RESULTS: The median patient age was 63 years (range, 50-76), and the pretreatment prostate-specific antigen level was 5.5 ng/mL (range, 0.6-13.5). The Gleason score was ≤6 in 125 patients and was 7 in 4 patients. The median follow-up period was 40 months (range, 24-111), and the median D(90) was 186 Gy. The median minimal dose received by 30% of the urethra was 203 Gy, and the median rectal volume receiving a minimum of 100% of the prescribed dose was 0.81 cm(3). Acute Grade 2 genitourinary toxicity was seen in 5.4% and late Grade 2 in 7%. Late urinary retention (Grade 3) was seen in 2 patients (1.5%). Grade 1 rectal bleeding occurred in 9.3% and Grade 2 in 2.3%. On univariate logistic regression analysis, none of the clinical and dosimetric parameters predicted for rectal bleeding. Of 110 men who were potent before treatment, 81% remained potent 5 years after treatment. Three biochemical failures and only one local failure developed. The 5-year biochemical no evidence of disease rate using the "nadir plus 2" definition was 96.8%. CONCLUSION: A D(90) of ≥180 Gy is associated with excellent biochemical disease-free survival and acceptable toxicity.

A phase III randomized trial of the timing of meloxicam with iodine-125 prostate brachytherapy.

PURPOSE: Nonsteroidal anti-inflammatory medication is used to reduce prostate edema and urinary symptoms following prostate brachytherapy. We hypothesized that a cyclooxygenase-2 (COX-2) inhibitor regimen started 1 week prior to seed implant might diminish the inflammatory response, thus reducing edema, retention rates, and symptom severity. METHODS AND MATERIALS: From March 2004 to February 2008, 316 men consented to an institutional review board-approved randomized study of a 4-week course of meloxicam, 7.5 mg orally twice per day, starting either on the day of implant or 1 week prior to implant. Brachytherapy was performed using iodine-125 seeds and was preplanned and performed under transrectal ultrasound (TRUS) and fluoroscopic guidance. Prostate volume obtained by MR imaging at 1 month was compared to baseline prostate volume obtained by TRUS planimetry and expressed as an edema factor. The trial endpoints were prostate edema at 1 month, International Prostate Symptom Score (IPSS) questionnaire results at 1 and 3 months, and any need for catheterization. RESULTS: Results for 300 men were analyzed. Median age was 61 (range, 45-79 years), and median TRUS prostate volume was 35.7 cc (range, 18.1-69.5 cc). Median IPSS at baseline was 5 (range, 0-24) and was 15 at 1 month, 16 at 3 months, and 10 at 6 months. Catheterization was required for 7% of patients (6.2% day 0 arm vs. 7.9% day -7 arm; p = 0.65). The median edema factor at 1 month was 1.02 (range, 0.73-1.7). 1.01 day 0 arm vs. 1.05 day -7 arm. Baseline prostate volume remained the primary predictor of postimplant urinary retention. CONCLUSIONS: Starting meloxicam 1 week prior to brachytherapy compared to starting immediately after the procedure did not reduce 1-month edema, improve IPSSs at 1 or 3 months, or reduce the need for catheterization.

Magnetic resonance imaging-defined treatment margins in iodine-125 prostate brachytherapy.

PURPOSE: Low-dose-rate prostate brachytherapy achieves a very high and effective intraprostatic dose. Implant quality parameters concentrate on the dose received by the prostate (D90, V100) but not that received by the periprostatic tissue. We calculated implant quality parameters, D90 and V100, for the magnetic resonance imaging (MRI)-defined prostate plus 2, 3, and 5 mm. METHODS AND MATERIALS: A total of 131 men with early-stage prostate cancer treated with iodine-125 brachytherapy represent all those treated with brachytherapy monotherapy in our institution in 2005. Postplan assessment was performed at 1 month using magnetic resonance (MR)-computed tomography (CT) fusion. The prostate V100 and D90 were calculated with 2-, 3-, and 5-mm margins. Results were compared with those in 8 patients with biopsy-proven local failure occurring in an experience of more than 1,100 implants. RESULTS: Mean prostate V100 (SD) and D90 (SD) were 95.6% (4.1) and 117.2% (12.7). For prostate plus a 2-mm margin the D90 was 107.9% (14.3) and for a 3-mm margin 96.0 % (14.0). For prostate plus a 5-mm margin, the D90 was only 78.4% (11.0). The 8 patients experiencing local failure, despite adequate implants, had a lower mean V100 of 91.2% (SD, 2.8; p = 0.0008) and D90 of 103.7% (SD, 8.3; p = 0.002) and significantly inferior margin coverage. CONCLUSIONS: Satisfactory coverage of a 2-mm and 3-mm periprostatic margin is obtained with the described planning approach. Coverage falls off significantly by 5 mm. The 8 patients who experienced local failure had significantly lower doses than the margin cohort. Although the V100 and D90 would be considered acceptable, the fall-off in margin coverage was observed by 3 mm.

The impact of perineural invasion on biochemical outcome after permanent prostate iodine-125 brachytherapy.

PURPOSE: Perineural invasion (PNI) in prostate biopsies is associated with increased risk of higher Gleason score and worse pathologic stage. We report the influence of PNI in biochemical no evidence of disease (bNED) survival after (125)I prostate brachytherapy (BT). METHODS AND MATERIALS: Pathology reports of 700 men with localized prostate cancer who underwent (125)I prostate BT in 1999-2008 were reviewed. The presence or absence of PNI in the biopsy was documented in 339 men. Clinical, treatment, and dosimetric parameters, along with PNI status, were evaluated for bNED survival, defined by "nadir+2" definition. RESULTS: Of the 339 patients, 87% had favorable risk and 13% intermediate risk. PNI was present in 89 patients (26%). After a median followup of 32 months, there were five biochemical failures (4: +PNI and 1: -PNI), of which one was local failure (+PNI). Actuarial 5-year bNED survival for the entire group was 97.0% (92.9% for +PNI; 99.2% for -PNI). In univariate analysis age, pretreatment prostate-specific antigen, Gleason score 7, and intermediate risk group predicted for worse biochemical outcome, whereas the presence of PNI showed a trend toward significance (p=0.06). Some of the regression algorithms failed to converge because of low event rates. CONCLUSIONS: We report excellent biochemical control in 339 men treated with (125)I prostate BT. The presence of PNI showed a trend toward significance in predicting 5-year bNED survival but did not impact on local control and should not influence the decision to recommend BT for localized prostate cancer.

Median 5 year follow-up of 125iodine brachytherapy as monotherapy in men aged

OBJECTIVES: To report the genitourinary (GU) and gastrointestinal (GI) toxicity rates, erectile function preservation, and biochemical outcome (bNED) in men aged

The effect of obesity on rectal dosimetry after permanent prostate brachytherapy.

OBJECTIVES: Men with higher body mass index (BMI) tend to have more fatty tissue in prostate-rectum interface, which may reduce the rectal wall dose by the inverse square law. We hypothesized that men with higher BMI will have a lower dose to the rectal wall and less rectal toxicity after permanent prostate implant. METHODS: Prospectively collected data on rectal dosimetry/toxicity and BMI of 407 patients who underwent iodine-125 ((125)I) prostate implant were analyzed. Postimplant dosimetry used CT-MRI fusion on Day 30. Rectal wall was contoured on all slices where seeds were seen. The volume of rectal wall receiving the prescribed dose (RV(100) in cm(3)) and the dose to 1cc of rectal wall (RD(1cc)) were reported. Other factors evaluated for association with rectal dosimetry and toxicity included age, diabetes, hypertension, smoking, use of neoadjuvant hormones, T stage, baseline prostate volume, 1 month prostate edema, seed type and activity, and prostate dosimetry factors (the isodose enclosing 90% of the prostate volume [D(90)], the percentage of the prostate volume enclosed by the prescription [V(100)], and the percentage of the prostate volume enclosed by the 150% isodose [V(150)]). Rectal toxicity was reported as per Radiation Therapy Oncology Group criteria. RESULTS: BMIs ranged from 15.9 to 46.8 (mean+/-standard deviation [SD]: 27.8+/-4.2). The mean+/-SD values for RV(100) and RD(1cc) were 0.79+/-0.49cm(3) and 128.2+/-27.8Gy, respectively. There was a significant negative association of BMI with RV(100) (p=0.007) and RD(1cc) (p=0.01) on univariate analysis. The mean RV(100) and RD(1cc) for men with higher BMI (>27.8) were lower compared with their slimmer counterparts (0.70 vs. 0.86cm(3) and 123.4 vs. 132.4Gy, respectively). On multivariate analysis for RV(100) and RD(1cc), BMI remained significant (p-values 0.004 and 0.01, respectively) along with prostate volume and V(150), suggesting that anatomic factors are important in rectal dosimetry in prostate brachytherapy. Overall the incidence of Radiation Therapy Oncology Group acute rectal toxicity was 12% (Grade 2, 1.3%) and chronic 6% (Grade 2, 0.5%). No Grade 3 toxicity occurred. None of the factors evaluated were predictive for rectal toxicity. CONCLUSION: Men with a lower BMI received a higher rectal wall dose compared with those with higher BMI. This did not, however, translate into greater rectal toxicity.

Sequential comparison of seed loss and prostate dosimetry of stranded seeds with loose seeds in 125I permanent implant for low-risk prostate cancer.

PURPOSE: To compare stranded seeds (SSs) with loose seeds (LSs) in terms of prostate edema, dosimetry, and seed loss after (125)I brachytherapy. METHODS AND MATERIALS: Two prospective cohorts of 20 men participated in an institutional review board-approved protocols to study postimplant prostate edema and its effect on dosimetry. The LS cohort underwent brachytherapy between September 2002 and July 2003 and the SS cohort between April 2006 and January 2007. Both cohorts were evaluated sequentially using computed tomography-magnetic resonance imaging fusion-based dosimetry on Days 0, 7, and 30. No hormonal therapy or supplemental beam radiotherapy was used. RESULTS: Prostate edema was less in the SS cohort at all points (p = NS). On Day 0, all the prostate dosimetric factors were greater in the LS group than in the SS group (p = 0.003). However, by Days 7 and 30, the dosimetry was similar between the two cohorts. No seeds migrated to the lung in the SS cohort compared with a total of five seeds in 4 patients in the LS cohort. However, the overall seed loss was greater in the SS cohort (24 seeds in 6 patients; 1.1% of total vs. 0.6% for LSs), with most seeds lost through urine (22 seeds in 5 patients). CONCLUSION: Despite elimination of venous seed migration, greater seed loss was observed with SSs compared with LSs, with the primary site of loss being the urinary tract. Modification of the technique might be necessary to minimize this. Prostate dosimetry on Days 7 and 30 was similar between the SS and LS cohorts.