Neurocognitive function and quality of life in patients with newly diagnosed brain metastasis after treatment with intra-operative cesium-131 brachytherapy: a prospective trial.

Intraoperative permanent Cesium-131 (Cs-131) brachytherapy can provide a viable alternative to WBRT with excellent response rates and minimal toxicity. This study reports the results of the prospective trial of the impact of intraoperative Cs-131 on neurocognitive function and quality of life (QoL) in patients with resected brain metastases. Between 2010 and 2012, 24 patients with newly diagnosed metastasis to the brain were accrued on a prospective protocol and treated with Cs-131 brachytherapy seeds after surgical resection. Physicians administered the mini-mental status examination (MMSE) and functional assessment of cancer therapy-brain (FACT-Br) questionnaire to all patients before treatment and again every 2 months for the duration of 6 months with additional follow-up again at 12 months. Wilcoxon rank sum test was used to analyze statistically significant changes in MMSE over time and paired t test was used to analyze changes in FACT-BR. There was a statistical improvement in overall FACT-BR score at 4 and 6 months of follow-up when compared to baseline (162 vs. 143, P = 0.004; 164 vs. 143, P = 0.005 respectively) with a non-significant trend toward improvement at 2 and 12 months (154 vs. 143, P = 0.067; 159 vs. 149, P = 0.4). MMSE score was statistically improved at 4 and up to 12 months compared to pre-treatment MMSE (30 vs. 29, P = 0.017; 30 vs. 29, P = 0.001 respectively). Patients with brain metastasis who received intra-operative permanent Cs-131 brachytherapy implants saw an improvement of their neurocognitive status and self-assessment of QoL. In addition to the excellent local control of metastasis, this approach may contribute to the improvements in cognitive function and QOL.

Implementation and early clinical results utilizing Cs-131 permanent interstitial implants for gynecologic malignancies.

OBJECTIVE: Permanent interstitial brachytherapy is an ideal yet underutilized treatment modality for accessible, small volume gynecological malignancies. We present early clinical results utilizing a new permanent isotope, Cs-131. METHODS: A retrospective review was performed evaluating patients treated with Cs-131 permanent interstitial radiation at our institution from July 2011 through June 2013. Doses were most commonly prescribed and calculated to a depth of 5mm using Paterson-Parker planar implant rules for Au-198. This activity was converted to air-kerma strength (U). A conversion factor of 1.1 was applied based on RBE calculations, clinical observation and experience. RESULTS: 14 patients were identified among whom 17 Cs-131 implants were performed. Seven patients were implanted as sole therapy, and a median dose of 50 Gy was delivered. Ten implants were performed as boost within a more extensive radiation treatment plan. In these patients, a median implant dose of 27.5 Gy was used and the median total dose delivered in combination was 78.25 Gy. After a median follow up of 12 months, the actuarial local control rate was 84.4%. A very low level of grade 1-3 reactions was observed with no fistula formations or other severe side effects. CONCLUSIONS: Permanent interstitial brachytherapy with Cs-131 was well tolerated with favorable early results compared to other series. Cs-131 has multiple favorable properties, including minimal radiation exposure to treating staff, and should be considered as a therapeutic option in appropriately selected patients. A methodology for dose prescription, calculation of radioactivity required and distribution of the isotope is also presented.

Redefining bladder neck dose in low-dose-rate prostate brachytherapy-Can we improve urinary toxicity without impacting disease control?

BACKGROUND: We sought to assess the impact of bladder neck dose (BND) on patient reported urinary toxicity, and feasibility of relative urethral sparing technique in prostate brachytherapy (PB). METHODS AND MATERIALS: We retrospectively identified bladder neck as a point dose on post-implant CT scans in patients treated with 131Cs PB. Urinary symptoms were assessed through EPIC questionnaires. Patient cohorts were identified based on mean BND as a percentage of prescription dose with toxicity assessment at each time point. RESULTS: In our cohort of 542 patients, BND was associated with clinically significant acute urinary symptoms and chronic symptoms, as patients receiving >70% of the prescription dose had significantly worse overall EPIC scores than patients receiving ≤70% of prescription dose. There was no difference in bDFS between patients receiving BND ≤70% (96% bDFS) and >70% (94% bDFS) at a median follow up of 57 months. CONCLUSIONS: BND has a significant impact on both acute and chronic urinary symptoms, with reduced symptoms reported with BND <70% of prescription dose. With a median follow up of 4.7 years, excellent bDFS has thus far been achieved with relative urethral and bladder neck sparing. Utilizing this constraint should improve urinary symptoms without impacting disease control.

Feasibility of collagen matrix tiles with cesium-131 brachytherapy for use in the treatment of head and neck cancer.

BACKGROUND: Locoregional failure is a unique and challenging problem in head and neck cancer with controversy surrounding the use of re-irradiation in the treatment. We aimed to evaluate the dosimetry and technical parameters in utilizing a collagen matrix with embedded Cesium-131 (Cs-131) radioactive isotope seeds as it relates to dose distribution and dose to carotid artery. METHODS AND MATERIALS: Cadaveric feasibility study randomizing Cs-131 strands alone or Cs-131 with collagen matrix to be placed into neck dissection defects. For the dose computation, physicists employed the TG-43 dosimetry calculation algorithm with a point source assumption to compute the dose. Carotid arteries were contoured in MIM-Symphony software and the carotid artery maximum and mean doses were calculated in accordance with TG-43 specifications. Ease of use of collagen matrix tiles on a 7-point Likert scale and mean radiation dose to the carotid artery. RESULTS: Ease of use score was higher in collagen matrix compared to stranded seeds with a mean score of 6.3 +/- 1.2 compared to 4.5 +/- 0.87. Time of implantation was statistically significantly, p = 0.031, lower in the collagen matrix group (M = 5.17 min, SD = 4.62) compared to stranded seeds (M = 15.83 min, SD = 3.24). Mean radiation dose to the carotid artery was 62.8 Gy +/- 9.46 in the collagen matrix group compared to 108.2 Gy +/- 55.6 in the traditional Cs-131 seeds group. CONCLUSIONS: We present a feasibility and concept cadaveric study using a collagen matrix with Cesium-131 demonstrating preliminary evidence to support its ease of use, decreased time to implantation, and decreased dose delivered to the carotid artery.

Cs-131 as an experimental tool for the investigation and quantification of the radiotoxicity of intracellular Auger decays in vitro.

PURPOSE: In this work, we set out to provide an experimental setup, using Cs-131, with associated dosimetry for studying relative biological effectiveness (RBE) of Auger emitters. MATERIAL AND METHODS: Cs-131 decays by 100% electron capture producing K- (9%) and L- (80%) Auger electrons with mean energies of 26 keV and 3.5 keV, respectively, plus ≈ 9.4 very low energy electrons (<0.5 keV) per decay. Cs-131 accumulates in the cells through the Na+/K+-ATPase. By this uptake mechanism and the alkali chemistry of Cs+, we argue for its intracellular homogeneous distribution. Cs-131 was added to the cell culture medium of HeLa and V79 Cells. The bio-kinetics of Cs-131 (uptake, release, intracellular distribution) was examined by measuring its intracellular activity concentration over time. Taking advantage of the 100% confluent cellular monolayer, we developed a new and robust dosimetry that is entrusted to a quantity called SC-value. RESULTS: The SC-values evaluated in the cell nucleus are almost independent of the nuclear size and geometry. We obtained dose-rate controlled RBE-values for intracellular Cs-131 decay. Using the γH2AX assay, the RBE was 1 for HeLa cells. Using the clonogenic cell survival, it was 3.9 for HeLa cells and 3.2 for V79 cells. CONCLUSION: This experimental setup and dosimetry provides reliable RBE-values for Auger emitters in various cell lines.

Treatment of intermediate-risk prostate cancer with Cs-131: Long-term results from a single institution.

PURPOSE: To evaluate our institutional outcomes utilizing Cs-131 prostate brachytherapy (PB) for the intermediate-risk (IR) group of prostate cancer patients. METHODS AND MATERIALS: We reviewed a prospectively collected database of men treated with Cs-131 PB between 2006 and 2019. Patients with less than 24-months follow-up were excluded. Patients were classified as IR if they had one of the following factors: Gleason Score 7, prostate specific antigen >10 but <20 ng/mL, or T2b-c on clinical exam. We defined unfavorable-IR (UIR) as having either Grade Group 3, >1 IR factors, or ≥50% positive core biopsies. The Kaplan-Meier method was used to estimate actuarial event-time probabilities for biochemical freedom from disease (BFD). RESULTS: A total of 335 patients with a median follow-up of 70.1 months (IQR 48.3-106.3 months) were identified. Androgen deprivation therapy (ADT) was used in 7.2% of patients. Favorable-IR (FIR) patients were commonly treated with PB alone (91.8%). FIR patients who underwent PB alone had a 5-year BFD of 98.1%. UIR patients were commonly treated with external beam radiotherapy plus PB (61.2%). These patients had 5-year BFD of 91.1%. The 5-year BFD for UIR patients treated without ADT was 90.9%, whereas it was 95.0% among UIR patients treated with ADT (log-rank p = 0.83). CONCLUSIONS: FIR patients have excellent outcomes when treated with PB alone. External beam radiotherapy plus PB is a reasonable treatment approach for UIR patients. Future studies may elucidate which IR patients would benefit from treatment intensification.

Safety and patterns of survivorship in recurrent GBM following resection and surgically targeted radiation therapy: Results from a prospective trial.

BACKGROUND: Treatment of recurrent glioblastoma (GBM) remains problematic with survival after additional therapy typically less than 12 months. We prospectively evaluated whether outcomes might be improved with resection plus permanent implantation of a novel radiation device utilizing the gamma-emitting isotope Cs-131 embedded within bioresorbable collagen tiles. METHODS: Recurrent histologic GBM were treated in a single-arm trial. Following radiation, the surgical bed was lined with the tiles. Subsequent treatments were at the treating physician's discretion. RESULTS: 28 patients were treated (20 at first recurrence, range 1-3). Median age was 58 years, KPS was 80, female:male ratio was 10:18. Methylguanine methyltransferase (MGMT) was methylated in 11%, unmethylated in 18%, and unknown in 71%. Post implant, 17 patients (61%) received ≥1 course of systemic therapy. For all patients, Kaplan-Meier estimates of median time to local failure were 12.1 months, post-implant survival was 10.7 months for all patients and 15.1 months for patients who received systemic therapy; for all patients, median overall survival from diagnosis was 25.0 months (range 9.1-143.1). Sex, age, and number of prior progressions were not statistically significant. Local control was continuously maintained in 46% of patients. Two deaths within 30 days occurred, one from intracranial hemorrhage and one after persistent coma. Three symptomatic adverse events occurred: one wound infection requiring surgery and two late radiation brain injury, resolved non-surgically. CONCLUSION: This pre-commercial trial demonstrated acceptable safety and favorable post-treatment local control and survival. The device has received FDA clearance for use in newly diagnosed malignant and all recurrent intracranial neoplasms.

Surviving Over a Decade With Glioblastoma: A Clinical Course Characterized by Multiple Recurrences, Numerous Salvage Treatments, and Novel Use of Cesium-131 Tiles.

The prognosis for patients diagnosed with recurrent glioblastoma (GBM) remains poor, with no clear standard of care regarding salvage therapy. Common approaches include chemotherapy, re-resection, tumor treating fields, and reirradiation. However, most studies have shown these to have limited benefits. Reirradiation is particularly difficult due to concern for increased risk of toxicity to surrounding normal brain tissue. A novel intracranial brachytherapy system called GammaTile® (GT Medical Technologies, Tempe, Arizona) involves the placement of Cesium-131 radioactive tiles in the tumor cavity following maximal safe resection. This allows for a highly conformal dose distribution with rapid fall-off to minimize overlap with prior radiation fields and for the application of radiation directly to the high-risk tumor bed. This case report highlights a patient with GBM who survived 11.5 years through multiple recurrences and discusses the many salvage treatments he received, including bevacizumab, irinotecan, and stereotactic radiosurgery (SRS). This case exemplifies that aggressive systemic and local therapies can work well in select patients allowing for long-term survival with a good quality of life. Further efforts should be made to identify which patients may benefit from these therapies. The case study additionally reports on the use of GammaTile therapy. Due to prior external beam radiation therapy and SRS to the treatment site, further external beam radiation options were limited, and the patient was offered GammaTile as local therapy. Although it did not provide a survival benefit in this case due to progressive disease outside of the field of treatment, GammaTile serves as a valuable option in providing local therapy to patients who can no longer receive further radiation. It should be used with careful consideration in lesions characterized by aggressive local invasion.

Resection and Surgically Targeted Radiation Therapy for the Treatment of Larger Recurrent or Newly Diagnosed Brain Metastasis: Results From a Prospective Trial.

Introduction Achieving durable local control (LC) for larger (e.g., >2-3 cm) brain metastasis whether newly diagnosed or recurrent remains problematic. Resection (R) alone is typically insufficient and adding radiation therapy (RT) still results in a 12-month recurrence rate of 20% or more in many series. Hypothesizing that R plus immediate radiation utilizing brachytherapy may improve outcomes for this cohort of patients, we designed and prospectively evaluated a permanently implanted surgically targeted radiation therapy (STaRT) device consisting of cesium-131 (Cs-131) seeds positioned within a collagen carrier (GammaTile, GT Medical Technologies, Tempe, AZ). The device was designed to prevent direct source-to-brain contact and maintain inter-source spacing after closure. Methods This was a subgroup analysis of a cohort of patients with either recurrent or previously untreated brain metastases enrolled in a prospective, multi-histology single-arm trial (ClinicalTrials.gov, NCT#03088579), conducted between February 2013 and February 2018, of resection and tumor bed brachytherapy with Cs-131 containing permanently implanted collagen tiles to deliver 60 Gray (Gy) at .5 cm depth. No additional local therapy was given without progression. Results A total of 16 metastases in 11 patients were treated; 12 tumors were recurrent and four were previously untreated. The median preoperative maximum diameter was 3.2 cm (range: 1.9-5.1 cm). Histology was seven breasts, six lungs, and three sarcomas. The median age was 60 years (range: 41-80 years); the Karnofsky Performance Status (KPS) was 70 (range: 70-90). The cohort consisted of seven females and four males. The mean time for implantation completion was five minutes. The median overall survival (OS) was 9.3 months. At a median radiographic follow-up of 9.5 months' treatment, site progression was found in 1/16 (6%) at 10.9 months, and the median treatment site time-to-progression (TTP) has not been reached [95% confidence interval (CI): >10.9 months]. At 12 months, the Kaplan-Meier (K-M) estimates for LC after R+STaRT for all tumors was 83%; for previously untreated tumors, LC at 12 months was 100% and for recurrent tumors, it was 80%. Two tumor beds (12.5%) experienced radiation brain changes: one had grade two and the other grade three. No surgical adverse events occurred. Conclusion In this single-arm precommercial study, R+STaRT demonstrated excellent safety and LC in this cohort. The device has recently received FDA clearance for use in newly diagnosed and recurrent brain metastasis, and randomized clinical trials vs. standard of care treatments in both settings are scheduled to open in 2020.

A matched-pair analysis of clinical outcomes after intracavitary cesium-131 brachytherapy versus stereotactic radiosurgery for resected brain metastases.

OBJECTIVE: Adjuvant radiation therapy (RT), such as cesium-131 (Cs-131) brachytherapy or stereotactic radiosurgery (SRS), reduces local recurrence (LR) of brain metastases (BM). However, SRS is less efficacious for large cavities, and the delay between surgery and SRS may permit tumor repopulation. Cs-131 has demonstrated improved local control, with reduced radiation necrosis (RN) compared to SRS. This study represents the first comparison of outcomes between Cs-131 brachytherapy and SRS for resected BM. METHODS: Patients with BM treated with Cs-131 and SRS following gross-total resection were retrospectively identified. Thirty patients who underwent Cs-131 brachytherapy were compared to 60 controls who received SRS. Controls were selected from a larger cohort to match the patients treated with Cs-131 in a 2:1 ratio according to tumor size, histology, performance status, and recursive partitioning analysis class. Overall survival (OS), LR, regional recurrence, distant recurrence (DR), and RN were compared. RESULTS: With a median follow-up of 17.5 months for Cs-131-treated and 13.0 months for SRS-treated patients, the LR rate was significantly lower with brachytherapy; 10% for the Cs-131 cohort compared to 28.3% for SRS patients (OR 0.281, 95% CI 0.082-0.949; p = 0.049). Rates of regional recurrence, DR, and OS did not differ significantly between the two cohorts. Kaplan-Meier analysis with log-rank testing showed a significantly higher likelihood of freedom from LR (p = 0.027) as well as DR (p = 0.018) after Cs-131 compared to SRS treatment (p = 0.027), but no difference in likelihood of OS (p = 0.093). Six (10.0%) patients who underwent SRS experienced RN compared to 1 (3.3%) patient who received Cs-131 (p = 0.417). CONCLUSIONS: Postresection patients with BM treated with Cs-131 brachytherapy were more likely to achieve local control compared to SRS-treated patients. This study provides preliminary evidence of the potential of Cs-131 to reduce LR following gross-total resection of single BM, with minimal toxicity, and suggests the need for a prospective study to address this question.

Cs-131 brachytherapy for patients with recurrent glioblastoma combined with bevacizumab avoids radiation necrosis while maintaining local control.

PURPOSE: Re-irradiation of recurrent glioblastoma (GBM) may delay further recurrence but re-irradiation increases the risk of radionecrosis (RN). Salvage therapy should focus on balancing local control (LC) and toxicity. We report the results of using intraoperative Cesium-131 (Cs-131) brachytherapy for recurrent GBM in a population of patients who also received bevacizumab. METHODS AND MATERIALS: Twenty patients with recurrent GBM underwent maximally safe neurosurgical resection with Cs-131 brachytherapy between 2010 and 2015. Eighty Gy was prescribed to 0.5 cm from the surface of the resection cavity. All patients previously received adjuvant radiotherapy and temozolomide, and received bevacizumab before or after salvage brachytherapy. Seven of 20 (35%) tumors were multiply recurrent and had been previously salvaged with external beam radiotherapy. Patients received MRI scans every 2 months monitored for recurrence, progression, and RN. RESULTS: Median tumor diameter was 4.65 cm (range, 1.2-6.3 cm). Median number of seeds pace was 41 (range, 20-74) with total seed activity 96.8U (range, 41.08-201.3U). At a median followup of 19 months, crude LC was 85% and median overall survival was 9 months (range, 5-26 months). There were two postoperative wound infections (10%), three seizures (15%), and 0% incidence of RN. CONCLUSIONS: Our study demonstrates that while LC and survival are similar to other studies of postoperative external beam radiotherapy, no RN occurred in any of these patients, including 7 multiply re-irradiated patients. Of interest, there were patients with multiple recurrences whose survival extended beyond 20 months. These findings suggest that the use of highly conformal Cs-131 brachytherapy is a promising treatment for patients with recurrent GBM with minimal risk of development of RN.

Resection Cavity Contraction Effects in the Use of Radioactive Sources (1-25 versus Cs-131) for Intra-Operative Brain Implants.

Background and Objectives Intra-parenchymal brain surgical resection cavities usually contract in volume following low dose rate (LDR) brachytherapy implants. In this study, we systematically modeled and assessed dose variability resulting from such changes for I-125 versus Cs-131 radioactive sources. Methods Resection cavity contraction was modeled based on 95 consecutive patient cases, using surveillance magnetic resonance (MR) images. The model was derived for single point source geometry and then fully simulated in 3D where I-125 or Cs-131 seeds were placed on the surface of an ellipsoidal resection cavity. Dose distribution estimated via TG-43 calculations and biological effective dose (BED) calculations were compared for both I-125 and Cs-131, accounting for resection cavity contractions. Results Resection cavity volumes were found to contract with an effective half-life of approximately 3.4 months (time to reach 50% of maximum volume contraction). As a result, significant differences in dose distributions were noted between I-125 and Cs-131 radioactive sources. For example, when comparing with static volume, assuming no contraction effect, I-125 exhibited a 31.8% and 30.5% increase in D90 and D10 values (i.e., the minimal dose to 90% and 10% of the volume respectively) in the peripheral target areas over the follow-up period of 20.5 months. In contrast, Cs-131 seeds only exhibited a 1.44% and 0.64% increase in D90 and D10 values respectively. Such discrepancy is likewise similar for BED calculations. Conclusion Resection cavity contractions affects Cs-131 dose distribution significantly less than that of I-125 for permanent brain implants. Care must be taken to account for cavity contractions when prescribing accumulative doses of a radioactive source in performing the brain implant procedures.

Seed migration to the spinal canal after postresection brachytherapy to treat a large brain metastasis.

PURPOSE: Seed migration after interstitial prostate brachytherapy has been well documented in the literature. However, there have been no detailed reports of seed migration after permanent interstitial brachytherapy to treat cerebral malignancies. In this article, the authors report a rare case of seed migration after adjuvant cesium-131 ((131)Cs) brachytherapy was used to treat a large paraventricular brain metastasis. METHODS AND MATERIALS: The patient was a 63-year-old man with a 5.8-cm right frontal metastasis abutting the right lateral ventricle and causing severe edema and mass effect. The patient was enrolled in an ongoing clinical trial at our institution to receive permanent intraoperative (131)Cs brachytherapy in an effort to prevent tumor recurrence in the resection cavity. Stranded seeds were covered with Surgicel, and the cavity was filled with Tisseel to prevent seed migration. RESULTS: Imaging obtained at 54 days postsurgery showed no seed migration, but imaging obtained at 158 days revealed 12 brachytherapy seeds in the spinal canal from T11 to S2. The seeds were left in place because they were inactive at this time due to the short half-life of (131)Cs (9.7 days); they remained stable on followup imaging, and the patient was asymptomatic. CONCLUSIONS: Although the clinical consequences remain unclear, the migration of inactive seeds is not currently considered to be a complication of intracerebral brachytherapy and we do not believe that additional measures must be taken to prevent it.

Surgical Technique and Clinically Relevant Resection Cavity Dynamics Following Implantation of Cesium-131 (Cs-131) Brachytherapy in Patients With Brain Metastases.

BACKGROUND: Cesium-131 (Cs-131) brachytherapy is used to reduce local recurrence of resected brain metastases. In order to ensure dose homogeneity and reduce risk of radiation necrosis, inter-seed distance and cavity volume must remain stable during delivery. OBJECTIVE: To investigate the efficacy of the "seeds-on-a-string" technique with intracavitary fibrin glue in achieving cavity volume stability. METHODS: We placed intra-operative Cs-131 brachytherapy in 30 cavities post-resection of brain metastases. Seeds-on-a-string were placed like barrel staves within the cavity with fibrin glue. Serial MRI imaging occurred post-operatively. Pre-operative tumor volumes were compared with post-operative cavity volumes to evaluate volume stability. Thirty patients who underwent post-resective stereotactic radiosurgery (SRS) were used as a control group for volumetric comparison. RESULTS: Cs-131 and SRS patients exhibited consistent cavity shrinkage over the median 110-day follow-up (p<.001), with total median shrinkage of 56.5% (Cs-131) and 84.8% (SRS). During the first month when ~88% of Cs-131 dosage is delivered, however, there was non-significant volume decrease in the Cs-131 group (median 22.0%; p=.063), while SRS patients showed significantly more shrinkage (46.7%; p=.042). No events of radiation necrosis occurred in either group. CONCLUSION: Cs-131 patients exhibited significantly less cavity shrinkage than SRS patients during the first critical month with 88% Cs-131 dose delivery. This significant difference in shrinkage suggests that the intracavitary seeds-on-a-string technique facilitates increased cavity stability, promoting more homogenous dose delivery.

Dosimetric differences between intraoperative and postoperative plans using Cs-131 in transrectal ultrasound-guided brachytherapy for prostatic carcinoma.

The aim of the study was to investigate the differences between intraoperative and postoperative dosimetry for transrectal ultrasound-guided transperineal prostate implants using cesium-131 ((131)Cs). Between 2006 and 2010, 166 patients implanted with (131)Cs had both intraoperative and postoperative dosimetry studies. All cases were monotherapy and doses of 115 were prescribed to the prostate. The dosimetric properties (D90, V150, and V100 for the prostate) of the studies were compared. Two conformity indices were also calculated and compared. Finally, the prostate was automatically sectioned into 6 sectors (anterior and posterior sectors at the base, midgland, and apex) and the intraoperative and postoperative dosimetry was compared in each individual sector. Postoperative dosimetry showed statistically significant changes (p < 0.01) in every dosimetric value except V150. In each significant case, the postoperative plans showed lower dose coverage. The conformity indexes also showed a bimodal frequency distribution with the index indicating poorer dose conformity in the postoperative plans. Sector analysis revealed less dose coverage postoperatively in the base and apex sectors with an increase in dose to the posterior midgland sector. Postoperative dosimetry overall and in specific sectors of the prostate differs significantly from intraoperative planning. Care must be taken during the intraoperative planning stage to ensure complete dose coverage of the prostate with the understanding that the final postoperative dosimetry will show less dose coverage.