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The post-implantation dosimetry for brachytherapy using Monte Carlo calculation by EGS5 code combined with the source strength regression was investigated with respect to its validity. In this method, the source strength for the EGS5 calculation was adjusted with the regression, so that the calculation would reproduce the dose monitored with the glass rod dosimeters (GRDs) on a water phantom. The experiments were performed, simulating the case where one of two (125)I sources of Oncoseed 6711 was lacking strength by 4-48%. As a result, the calculation without regression was in agreement with the GRD measurement within 26-62%. In this case, the shortage in strength of a source was neglected. By the regression, in order to reflect the strength shortage, the agreement was improved up to 17-24%. This agreement was also comparable with accuracy of the dose calculation for single source geometry reported previously. These results suggest the validity of the dosimetry method proposed in this study.

Purpose: To evaluate the effects of four different prostate cancer treatments on quality of life (QoL) and patient satisfaction. Methods: Ninety-six prostate cancer patients were treated with hormone therapy, radical retropubic prostatectomy, high dose rate brachytherapy, or low dose rate brachytherapy. We assessed general, cancer-specific, and prostate disease-specific QoL. More than one year since commencement of treatment, the patients were asked the following questions: 1) How do you feel about your treatment? 2) Would you undergo the same treatment again? Results: The comparison of baseline and 12-month results showed that general and cancer-specific QoL had changed little in all groups. At baseline, the general and cancer-specific QoL tended to be lower in the hormone therapy patients. In the radical the retropubic prostatectomy patients, all scores on the Medical Outcomes Study 36-Item Short Form were worse than the baseline scores at three months. Scores for the International Index of Erectile Function-5 had also worsened, with no recovery. In the low-dose rate brachytherapy patients, the prostate disease-specific QoL at baseline tended to improve. However, the satisfaction levels for each treatment were reasonably good, and most patients would choose the same treatment again. Conclusions: The results of each of the four treatments differed in assessments of QoL. In the radical retropubic prostatectomy patients, the decrease in the International Index of Erectile Function-5 scores was especially remarkable and did not show recovery. In contrast, both brachy therapy groups had attained superior sexual function. However, regardless of the quality of life evaluations, most patients surveyed were satisfied with their treatments and would choose the same treatment again.

PURPOSE: To investigate the role of low dose rate (LDR) brachytherapy-based multimodal therapy in high-risk prostate cancer (PCa) and analyze its optimal indications. MATERIALS AND METHODS: We reviewed the records of 50 high-risk PCa patients [clinical stage ≥ T2c, prostate-specific antigen (PSA) >20 ng/mL, or biopsy Gleason score ≥ 8] who had undergone 125I LDR brachytherapy since April 2007. We excluded those with a follow-up period

Low dose rate permanent prostate brachytherapy is an excellent choice for men with localized prostate cancer. We review the contemporary understanding of genitourinary toxicity after prostate brachytherapy with particular attention directed toward urinary retention and incontinence. Urinary retention, though typically transient, has been reported in 1.5-34 % of patients, and significantly impacts health-related quality of life. Pre-treatment predictors include prostate size and high pre-treatment urinary symptom score. Validated nomograms have recently been developed to prospectively identify those at risk for urinary retention. In patients with refractory bladder outlet obstruction, a minimal transurethral resection of the prostate (TURP) is employed following a time interval sufficient for delivery of the full prescribed radiation dose. Urinary incontinence is uncommon following brachytherapy but is strongly associated with prior or subsequent TURP, where published incidence reports range from 0-19 %. Ongoing research seeks to identify genetic polymorphisms that may select individuals at greater risk of developing radiation related toxicities.

Brachytherapy treatment planning systems (BTPS) are employing the American Association of Physicists in Medicine (AAPM) Task Group 43 (TG‐43)‐recommended dosimetric parameters of sources, which are measured in water. The majority of brachytherapy implant volumes are not homogeneous media. Particularly, an implant with multiple seeds significantly changes homogeneity of the implant volume. Heterogeneities, such as attenuation by adjacent seeds or interseed attenuation (ISA), are neglected to this day in all BTPS. The goal of this project is to determine a novel analytical method to evaluate the impact of the dose perturbations (P‐value) and/or interseed attenuation effect (ISA‐value). This method will be validated for low‐ and high‐energy brachytherapy seeds such as 125I and 192Ir using Monte Carlo (MC) simulation techniques. In this analytical model, determination of dose perturbation and interseed attenuation in a multisource brachytherapy implant is based on MC‐simulated 3D kernels of P‐values and ISA data for single active and single dummy configurations, arranged at different distances and orientations relative to each other. The accuracy of the final model in multisource implant configurations has been examined by a comparison of the calculated P‐values and ISA‐values with full Monte Carlo water simulations (FMCWS). This model enabled us to determine the total perturbation and ISA values for any multisource implant, and the results are in excellent agreement with the FMCWS data. The advantage of this model to FMCWS for daily clinical application is the speed of the calculations and ease of the implementation. The new perturbation and ISA formulism have shown a better accuracy for 192Ir than 125I due to Compton scattering and its independence of the atomic number of the chemical composition of the phantom materials. The maximum difference between the ISA model and FMCWS for all cases was less than 5%. This new model can provide inputs for brachytherapy planning software to consider the ISA effect in dose calculations based on TG‐43U1 algorithm. This approach is applicable for energy range of 125I to 192Ir sources. PACS number: 87.53.Jw

Low dose-rate brachytherapy as a boost after concomitant chemoradiation therapy is a standard of care for locally advanced anal carcinoma, providing a rigorous selection taking into account the initial staging and tumor response to external beam radiotherapy. Local control is likely to be superior when the boost is performed with brachytherapy than with external beam radiotherapy. The several steps of the brachytherapy procedure are described. The standard treatment scheme is a concomitant chemoradiation therapy, including 45 Gy (1,8 Gy × 5) pelvic external beam radiotherapy and two courses of 5-fluorouracil and mitomycin-C, followed by a 15 Gy brachytherapy boost with a gap limited to 2 to 3 weeks. Higher irradiation dose for the most advanced cases has not yet demonstrated a therapeutic gain in terms of colostomy free survival. Exclusive brachytherapy for in-situ carcinoma or invasive carcinoma less than 10mm is not recommended due to a high risk of local recurrence. Pulsed dose rate brachytherapy is an alternative to low dose rate brachytherapy (iridium wires) providing the respect of the recommended dose rate (0.5 to 1 Gy/hour). High dose rate brachytherapy is still under evaluation.

Background To compare the PSA value at the last follow-up of patients who underwent prostate low-dose rate brachytherapy (LDR-BT) with that of patients who underwent intensity-modulated radiation therapy (IMRT). Methods A total of 610 prostate cancer patients (cT1c-3bN0M0) were enrolled, and 445 of them underwent LDR-BT, while 165 received IMRT (74–76 Gy). The median follow-up period of these two groups was 75 months (LDR-BT) and 78 months (IMRT), respectively. We also evaluated the biochemical recurrence (BCR)-free rate using two definitions (Phoenix definition and PSA ≥ 0.2 ng/mL). Results The percentage of patients who achieved PSA

Purpose To develop a plastic scintillation detector (PSD) capable of accurately measuring dose around a low-dose-rate (LDR) iodine-125 ( 125 I) radioactive seed as a first step toward in vivo dosimetry for prostate LDR brachytherapy. Methods Using a GEANT4 based Monte Carlo code, photon energy distribution at any position around a realistic 125 I source model was obtained. This energy distribution was convolved with the expected energy response from a plastic scintillator and dosimetry accuracy was evaluated. A PSD was constructed and validated in a water phantom for the entire range of clinically relevant positions around an 125 I radioactive seed. Results The effect of energy dependence on dosimetry accuracy was shown to be limited, with a maximum relative difference of 1.2% from the calibration condition. A sophisticated approach to account for the energy dependence of PSDs is, therefore, not required if the detector is calibrated using the same model of radioactive seed or a geometrically similar one. The measurements were in good agreement with theoretical models for the entire clinical range. Conclusions This study shows that PSDs can be used for accurate dosimetry in real time around a single 125 I seed used in LDR prostate brachytherapy and is promising for clinical applications.

Purpose The aim of this study is to report the long-term outcomes and toxicities from a large cohort of patients with localized prostate cancer treated with low-dose-rate intraoperatively planned brachytherapy. Methods and Materials Prostate-specific antigen levels, urinary symptoms, and erectile function were recorded at baseline, and each followup visit was then entered into a prospective database. Urinary toxicity requiring procedural intervention was retrospectively verified using an integrated electronic medical system. A separate cross-sectional survey was performed to measure postimplant sexual function. Results A total of 822 patients with low and favorable intermediate-risk prostate cancer were treated at our institution between 2003 and 2013. The Kaplan–Meier estimates for biochemical recurrence for our cohort were 95% and 87% at 5 and 10 years, respectively. Cystoscopy, transurethral resection of prostate, or dilatation was required for 7.1% of 720 patients with more than 2 years of followup. At a median followup of 3.7 years, 64.4% of patients retained adequate erectile function for intercourse, with 54% of patients who were no longer sexually active postimplant reporting social factors as the primary reason. Conclusions Our institutional experience with intraoperative low-dose-rate prostate brachytherapy yielded excellent long-term results with a low incidence of urinary and sexual toxicity.

Background/aim: Low dose rate brachytherapy has been used as salvage therapy for locally recurrent prostate cancer (PC) after primary external beam radiation therapy (EBRT), along with surgery and cryotherapy. All these techniques, in particular, when applied to the whole gland, involve a relatively high risk of toxicity and may worsen the patient’s quality of life. Our aim is to evaluate the results of whole-gland salvage brachytherapy (SBT) after primary EBRT in terms of toxicity, functional outcomes, and efficacy. Materials and methods: We retrospectively reviewed clinical data on 19 patients consecutively treated with SBT at our institution between June 2012 and November 2015. Local recurrences were identified with 11C-choline positron emission tomography/computed tomography and pelvic magnetic resonance imaging after biochemical recurrence according to Phoenix criteria (prostate-specific antigen nadir + 2). Low dose rate brachytherapy was performed by 125I permanent seeds implantation to the whole prostate gland, with a prescription dose of 130 Gy. At the time of SBT, only 2 patients were receiving androgen deprivation therapy. Acute and late toxicities were recorded using the CTCAE 4.0 scoring system. Quality of life was assessed using IPSS (International Prostate Symptoms Score) and IIEF (International Index of Erectile Function) questionnaires at baseline and 6, 12, and 24 months after SBT, and the respective mean values were compared using Student t test. Biochemical relapse-free survival (BRFS) was also calculated. Results: Median follow-up after SBT was 24 months. Of 19 patients, 2 patients experienced a G3 cystitis (10.2%) and 1 patient experienced a G4 proctitis (5.3%), respectively. Mean pre-SBT IPSS scores and 6, 12, and 24 months after SBT were 5.84, 10.22, 15.72, and 8.10, respectively. Mean pre-SBT IIEF scores and 6, 12, and 24 months after SBT were 8.42, 3.55, 7.89, and 6.40, respectively. At the time of analysis, only 2 patients showed a biochemical relapse (3-year BRFS 85.2%). The Student t test demonstrated a worsening of functional outcome 6 months and 1 year after treatment but a subsequent improvement 2 years after SBT. Conclusions: Salvage brachytherapy for recurrent PC after primary EBRT seems to be a feasible treatment for selected patients. Our series revealed a severe toxicity peak 6 months and 1 year after local re-treatment and then they decrease. Early BRFS rates are good. However, these are very preliminary results so further patient accrual, long-term follow-up, and prospective trials are needed in the future.

Permanent prostate brachytherapy is recognized as a standard of care for localized prostate cancer. Although most physicians performing permanent prostate implants have more commonly utilized ultrasound-guided techniques, MRI-guided radiosurgery (MARS) has emerged as an exciting advancement in the field. Compared to ultrasound and CT, MRI can reduce the level of target volume uncertainty given its superior soft tissue delineation. In this chapter, we will focus on essential concepts pertaining to MRI-guided LDR prostate brachytherapy for the management of localized prostate cancer including proper patient selection, pretreatment planning, implanting techniques, and postimplant assessment.

Purpose: To investigate the dosimetric difference due to the different point A definitions in cervical cancer lowdose-rate (LDR) intracavitary brachytherapy. Material and methods: Twenty CT-based LDR brachytherapy plans of 11 cervical patients were retrospectively reviewed. Two plans with point As following the modified Manchester system which defines point A being 2 cm superior to the cervical os along the tandem and 2 cm lateral (A os ), and the American Brachytherapy Society (ABS) guideline definition in which the point A is 2 cm superior to the vaginal fornices instead of os (A ovoid ) were generated. Using the same source strength, two plans prescribed the same dose to A os and A ovoid . Dosimetric differences between plans including point A dose rate, treatment volume encompassed by the prescription isodose line (TV), and dose rate of 2 cc of the rectum and bladder to the prescription dose were measured. Results: On average A ovoid was 8.9 mm superior to A os along the tandem direction with a standard deviation of 5.4 mm. With the same source strength and arrangement, A os dose rate was 19% higher than A ovoid dose rate. The average TV(A ovoid ) was 118.0 cc, which was 30% more than the average TV(A os ) of 93.0 cc. D 2cc /D(A prescribe ) increased from 51% to 60% for rectum, and increased from 89% and 106% for bladder, if the prescription point changed from A os to A ovoid . Conclusions: Different point A definitions lead to significant dose differences. Careful consideration should be given when changing practice from one point A definition to another, to ensure dosimetric and clinical equivalency from the previous clinical experiences. J Contemp Brachytherapy 2013; 5, 4: 222–226 DOI: 10.5114/jcb.2013.38836

Introduction: The feasibility and outcome of salvage robotic prostatectomy (SRP) following failed low-dose brachytherapy is unknown and historically associated with significant complicatio...

Brachytherapy is the use of radionuclides to treat malignancies or benign conditions by means of a radiation source placed close to or into the tumor or treatment site. This practice parameter refers only to the use of radionuclide brachytherapy. Brachytherapy alone or combined with external beam therapy plays an important role in the management and treatment of patients with cancer. Low-dose-rate (LDR) brachytherapy has traditionally been used for treating prostate, head and neck, breast, cervical, and endometrial cancers as well as obstructive bile duct, esophageal, or bronchial lesions. It has been practiced for over a century with a variety of sources including radium-226, cesium-137, and, more recently, iridium- 192, iodine-125, and palladium-103. Low-dose-rate (LDR) brachytherapy can be given as interstitial, intracavitary, intraluminal, and/or plesiotherapy to a wide variety of treatment sites. This practice parameter addresses sealed sources as they are used for LDR brachytherapy. It is recognized that unsealed sources (e.g., yttrium-90) are also a form of LDR brachytherapy.

Low-dose rate brachytherapy (LDR-BT) has been used in Sweden for more than a decade for treatment of low-risk prostate cancer. This study presents the outcome for patients treated with LDR-BT at a single institution with focus on the association between dose and biochemical failure-free survival (BFFS).In total 195 patients were treated with LDR-BT between 2004 and 2008. The patients were followed systematically for side effects for at least one year. PSA levels were followed regularly from three months and for at least five years. Outcome was analyzed in relation to clinical variables at baseline and to radiotherapy data.Kaplan-Meier estimated BFFS at five years was 95.7%. Dose to the prostate in terms of D90% was significantly associated with BFFS [HR 0.90 (95%CI 0.83-0.96), p = 0.002].Out data confirmed that absorbed dose is a predictive factor for BFFS for low-risk patients without androgen deprivation therapy. With our treatment routines and dosimetry, a D90% in the range of 170-180 Gy gives excellent outcomes with acceptable toxicity for patients with low-risk prostate cancer.

Aims To compare biochemical failure-free survival (BFFS) and overall survival for prostate cancer treated with stereotactic ablative radiotherapy (SABR), low dose rate (LDR) brachytherapy or external beam radiotherapy (EBRT) using a large Canadian multi-institutional database. Materials and methods Patients with low risk localised prostate cancer treated with SABR, LDR or EBRT and no androgen deprivation therapy were selected. Propensity score matching was used to create two sets of matched cohorts with LDR and EBRT serving as control groups. Kaplan–Meier survival analysis and Cox proportional hazards regression were used to compare differences in BFFS and overall survival between treatment groups. Results The pre-matched cohort contained 602 patients; the median follow-up was >5.0 years. There were no significant differences in BFFS before or after matching for SABR versus LDR but the prostate-specific antigen (PSA) nadir was lower after LDR. For the SABR versus EBRT, SABR had a BFFS trend before matching ( P = 0.08), which became significant after matching ( P Conclusions Using the Genitourinary Radiation Oncologists of Canada Prostate Cancer Risk Stratification database, low risk prostate cancer patients receiving SABR had similar BFFS compared with patients receiving LDR but better BFFS than EBRT patients. Further comparative studies of efficacy, quality of life and economic outcomes using a broader risk of patients are warranted.

This study evaluated the biochemical diseasefree survival (bDFS) rate, overall survival rate (OS) and toxicity after low-dose rate I125 permanent-implant prostate brachytherapy (LDR-BRT) in elderly patients affected by prostate cancer. Patients aged ≥65 years with a diagnosis of prostate cancer and treated at our institution were retrospectively evaluated. All patients received LDR-BRT as monotherapy; the prescribed dose was 145 Gy to the prostate. Patients were stratified according to the National Comprehensive Cancer Network (NCCN) recurrence risk groups. Biochemical failure was defined according to the American Society of Therapeutic Radiology and Oncology (ASTRO) criteria. The Radiation Therapy Oncology Group (RTOG) scale was used for toxicity. The bDFS was calculated from implant date to biochemical recurrence. Between June 2003 and December 2008, 80 elderly patients with a median age of 75 (range, 65–86) years were treated with LDR-BRT: 51 low risk (64%), and 29 intermediate risk (36%). Over a median follow-up period of 53 (range, 28–94) months, the global actuarial 5-year bDFS rate was 91.3% and the 5-year OS was 95%. Toxicity was mild: late grade-3 genitourinary toxicity was observed in only four patients (5%). Our data suggest that LDR-BRT is effective and safe as monotherapy in elderly patients.

As mandatory reporting of health care incidents becomes more prevalent, the need for effective strategies for analyzing historical reports to identify vulnerabilities is increasingly important. For this project, the research team reviewed existing event narratives collected by the U.S. Nuclear Regulatory Commission (NRC) that described errors with the use of nuclear byproducts in four medical treatment modalities: gamma knife stereotactic radiosurgery, high dose rate brachytherapy, low dose rate brachytherapy, and interstitial brachytherapy. This analysis had three levels: identification of possible system vulnerabilities based on historical data, analysis of event data for trends over time and for each treatment modality, and comparison of the suggested corrective actions with the implemented corrective actions for each event. The research team identified types of errors that were more prevalent with each treatment modality, along with discrepancies between suggested corrective actions and the implemented corrective actions. This project is a case study illustrating strategies for extracting valuable information from incident-reporting databases.

Low-intensity radioactive sources emitting low-energy photons are used in the clinic for low dose-rate brachytherapy treatments of tumours. The dosimetry of these sources is based on reference air kerma rate measurements. The absorbed dose rate to water at the reference depth d0?=?1?cm, , is then obtained by a conversion procedure with a large relative standard uncertainty of about 5%. This paper describes a primary standard developed at ENEA-INMRI to directly measure due to LDR sources. The standard is based on a large-angle and variable-volume ionization chamber, embedded in a graphite phantom and operating under ?wall-less air chamber? conditions. A set of correction and conversion factors, based on experiments and Monte Carlo simulations, are determined to obtain the value of Dw,1 cm from measurements of increment of ionization current with increasing chamber volume. The relative standard uncertainty on is 2.6%, which is appreciably lower than the current uncertainty. Characteristics of the standard, its associated uncertainty budget, and some experimental results are given for 125I BEBIG I25.S16.C brachytherapy seeds. Finally, results of the experimental determination of the dose-rate constant ?1 cm, traceable to the Dw,1 cm and the low-energy air kerma ENEA-INMRI standards, are given. The relative standard uncertainty on ?1 cm is 2.9%, appreciably lower than the typical uncertainty (4.8%) of the values available in the literature.

To investigate the significance of the percentage of positive biopsy cores (PPBCs) in predicting the biochem- ical outcome in patients with clinically localised prostate cancer undergoing low-dose rate brachytherapy (LDRB).  A total of 326 consecutive patients underwent LDRB between February 1997 and January 2007. The cohort consisted of 68.7%, 30.4% and 0.9% of low-, intermediate- and high-risk groups respectively as defined by the D'Amico classifica- tion. Patients were stratified according to PPBCs ( 50%).  Of the 326 men, 316 (97%) met the study criteria and were included in the analysis. The median follow-up was 66.3 (12.9-147.5) months. Thirty-eight men (12%) developed evidence of biochemical relapse as defined by the Phoenix defi- nition at a median of 44.5 (4-133) months. The overall 5-year and 10-year biochemical relapse-free rate (BRFR) was 91.9% (95% CI 87.9% to 94.6%) and 76.9% (95% CI 66% to 84%) respectively.  On univariate analysis, Gleason score (p=0.03), D'Amico risk groups (p=0.004) and PPBCs (p=0.001) were significant predictors of biochemical failure. In the multivariate model, the PPBCs (p=0.0006) and pretreatment PSA (p=0.004) were the only variables that predicted for biochemical failure. The 5-year biochemical relapse-free rate was 93.5%, 93.0% and 76.5% for the PPBCs 50% respectively (p=0.001). Conclusions:  The PPBC is an important independent predictor of the 5-year biochemical relapse-free survival after LDRB. This finding suggests that patients with high volume tumour are at increased risk of biochemical failure with LDRB.

Purpose To analyze the outcome after low-dose-rate (LDR) or high-dose-rate (HDR) brachytherapy for lip cancer. Methods and Materials One hundred and three patients with newly diagnosed squamous cell carcinoma of the lip were treated between March 1985 and June 2009 either by HDR ( n = 33) or LDR brachytherapy ( n = 70). Sixty-eight patients received brachytherapy alone, and 35 received tumor excision followed by brachytherapy because of positive resection margins. Acute and late toxicity was assessed according to the Common Terminology Criteria for Adverse Events 3.0. Results Median follow-up was 3.1 years (range, 0.3–23 years). Clinical and pathological variables did not differ significantly between groups. At 5 years, local recurrence-free survival, regional recurrence-free survival, and overall survival rates were 93%, 90%, and 77%. There was no significant difference for these endpoints when HDR was compared with LDR brachytherapy. Forty-two of 103 patients (41%) experienced acute Grade 2 and 57 of 103 patients (55%) experienced acute Grade 3 toxicity. Late Grade 1 toxicity was experienced by 34 of 103 patients (33%), and 5 of 103 patients (5%) experienced late Grade 2 toxicity; no Grade 3 late toxicity was observed. Acute and late toxicity rates were not significantly different between HDR and LDR brachytherapy. Conclusions As treatment for lip cancer, HDR and LDR brachytherapy have comparable locoregional control and acute and late toxicity rates. HDR brachytherapy for lip cancer seems to be an effective treatment with acceptable toxicity.

Purpose: The roles of postimplant dosimetry (PID) after permanent I-125 implant are to identify and rectify inadequate implants, assess the dosimetric quality indicators, and evaluate dose to the organs at risk. The aim of the current work was to assess the progress of prostate implant quality via postimplant dosimetry over seven years. Methods : The following factors were investigated to assess the PID results obtained over seven years: the improvement in implant technique, the computed tomography(CT) delineation-based PID versus ultrasound-CT (US-CT) fusion-based PID, and the evolution of parameters such as D90 and NDR (natural dose ratio). The correlation between dosimetric parameters and clinical outcomes were also evaluated. Results : The seven years PID learning curve shows clear changes in dosimetric trend for the 265 patients studied. Manual target contouring on CT was shown to overestimate the prostate volume when compared to ultrasound data, translating to CT-based D90 values being lower than US-CT D90. It was found that NDR does not contribute with additional dosimetric information to postimplant dosimetry evaluation. Patient follow-up data show that 4.7% patients have relapsed, and urinary retention was reported in 2.7% of the patients. Conclusions : CT-based PID was found less reliable than US-CT fusion-based PID due to target volume overestimation. This result shows the biased interpretation of low D90 values based on CT-based targeting, providing unreliable correlations between D90 and relapse probability. The low urinary retention statistics are in accordance with the PID data for the organ, as only 5.2% of patients had their PID D10 > 218 Gy, i.e., above the recommended GEC-ESTRO guidelines. Besides the “learning” component, the PID D90 curve is influenced by the PID technique.

What's known on the subject? and What does the study add? There appears to be a clear difference in cancer control outcomes for patients with Gleason scores of 3+4 and those with scores of 4+3 after radical prostatectomy. It has been documented that patients with Gleason 4+3 prostate cancer have higher incidences of non-organ-confined disease than those with primary pattern 3. Higher rates of extracapsular extension, seminal vesicle invasion and positive margins have been found to be associated with primary pattern 4 over 3. These higher rates of non-organ-confined disease can lead to increased biochemical failure, which, in turn, can lead to higher mortality rates. This study provides information on the prognostic significance of primary Gleason pattern in the brachytherapy management of prostate cancer. Study Type – Prognosis (case series) Level of Evidence 4 OBJECTIVES • To report the biochemical outcomes for Gleason 7 prostate cancer treated with brachytherapy. • To analyse the impact of the primary Gleason pattern as well as other disease- and treatment-related factors on outcome. PATIENTS AND METHODS • A total of 560 patients with Gleason 7 prostate cancer were treated between 1990 and 2008 with brachytherapy, alone or in combination with hormonal therapy and/or external beam radiation therapy. • There were 352 patients with Gleason pattern 3+4 and 208 with Gleason pattern 4+3. • The mean (range) presenting PSA level was 11.2 (1–300) ng/mL, and the median was 7.8 ng/mL. • The presenting clinical stages were T1b in 1%, T1c in 33%, T2a in 16%, T2b in 32%, T2c in 16% and T3 in 2% of patients. RESULTS • The actuarial freedom from biochemical failure rate at 10 years was 82%. • There was no significant difference between 10-year freedom from biochemical failure rates for patients with Gleason scores of 3+4 (79%) and those with scores of 4+3 (82%). • Biologically effective dose and presenting PSA level were both significant predictors of biochemical failure in multivariate analysis. CONCLUSIONS • The primary Gleason pattern in Gleason 7 prostate cancer shows no significant effect on biochemical failure when treated with brachytherapy. • These results are different from those found after radical prostatectomy and are probably attributable to the enhanced local control afforded by a brachytherapy approach to this disease subset.

Medical physicists need dosimeters such as gel dosimeters capable of determining three-dimensional dose distributions with high spatial resolution. To date, in combination with magnetic resonance imaging (MRI), polyacrylamide gel (PAG) polymers are the most promising gel dosimetry systems. The purpose of this work was to investigate the dose rate dependency of the PAGAT gel dosimeter at low dose rates. The gel dosimeter was used for measurement of the dose distribution around a Cs-137 source from a brachytherapy LDR source to have a range of dose rates from 0.97 Gy h−1 to 0.06 Gy h−1. After irradiation of the PAGAT gel, it was observed that the dose measured by gel dosimetry was almost the same at different distances (different dose rates) from the source, although the points nearer the source had been expected to receive greater doses. Therefore, it was suspected that the PAGAT gel is dose rate dependent at low dose rates. To test this further, three other sets of measurements were performed by placing vials containing gel at different distances from a Cs-137 source. In the first two measurements, several plastic vials were exposed to equal doses at different dose rates. An ionization chamber was used to measure the dose rate at each distance. In addition, three TLD chips were simultaneously irradiated in order to verify the dose to each vial. In the third measurement, to test the oxygen diffusion through plastic vials, the experiment was repeated again using plastic vials in a nitrogen box and glass vials. The study indicates that oxygen diffusion through plastic vials for dose rates lower than 2 Gy h−1 would affect the gel dosimeter response and it is suggested that the plastic vials or (phantoms) in an oxygen free environment or glass vials should be used for the dosimetry of low dose rate sources using PAGAT gel to avoid oxygen diffusion through the vials.

What's known on the subject? and What does the study add? Whole gland brachytherapy has been used to successfully treat prostate cancer but the protocol for focal therapy has not previously been established. The consensus findings provide guidance on patient selection for focal brachytherapy as well as recommendations for conducting therapy and patient follow-up. Low dose rate prostate brachytherapy is an effective treatment for localized prostate cancer. Recently, it has been considered for use in a focused manner whereby treatment is targeted only to areas of prostate cancer. The objective of focal brachytherapy is to provide effective cancer control for low-risk disease but with reduced genitourinary and rectal side-effects in a cost-effective way. We report on the outputs of a consensus meeting of international experts in brachytherapy and focal therapy convened to consider the feasibility and potential development of focal brachytherapy. A number of factors were considered for focal brachytherapy including optimal patient selection, disease characterization and localization, treatment protocols and outcome measures. The consensus meeting also addressed the design of a clinical trial that would assess the oncological outcomes and side-effect profiles resulting from focal brachytherapy.

Purpose: Post-implant dosimetry following prostate seed implantation (PSI) occasionally reveals suboptimal dosi- metric coverage of the gland. Published reports of re-implantation techniques have focused on earlier-generation tech- niques, including preplanned approaches and stranded seeds. The purpose of this case report is to describe a customizable approach to perform corrective re-implantation using loose seeds and intraoperative planning technique. Material and methods: This case report describes a 63-year-old male with favorable risk prostate adenocarcinoma receiving PSI. Thirty day post-implant dosimetric evaluation revealed suboptimal coverage of the base of the gland. Us- ing guidance from post-implant CT-images and real-time planning, the patient received a corrective re-implantation with intraoperative planning. Results: Post-implant dosimetry after re-implantation procedure with intraoperative planning yielded improved tar- get volume coverage that achieved standard dosimetric criteria. Conclusions: Re-implantation as a salvage treatment technique after sub-optimal PSI is a valid treatment option per- formed with intraoperative real-time planning. J Contemp Brachyther 2012; 4, 3: 176-181 DOI: 10.5114/jcb.2012.30684

Purpose The aim of this study was to evaluate the effectiveness of low-dose-rate brachytherapy for local control and relapse-free survival in squamous cell and basal cell carcinomas of the lips. We compared two groups: one with tumors on the skin and the other with tumors on the lip. Patients and methods All patients had been treated at Claudius Regaud Cancer Centre from 1990 to 2008 for squamous cell or basal cell carcinoma. Low-dose-rate brachytherapy was performed with iridium 192 wires according to the Paris system rules. On average, the dose delivered was 65 Gy. Results 172 consecutive patients were included in our study; 69 had skin carcinoma (squamous cell or basal cell), and 92 had squamous cell mucosal carcinoma. The average follow-up time was 5.4 years. In the skin cancer group, there were five local recurrences and one lymph node recurrence. In the mucosal cancer group, there were ten local recurrences and five lymph node recurrences. The 8-year relapse-free survival for the entire population was 80%. The 8-year relapse-free survival was 85% for skin carcinoma 75% for mucosal carcinoma, with no significant difference between groups. The functional results were satisfactory for 99% of patients, and the cosmetic results were satisfactory for 92%. Maximal toxicity observed was Grade 2. Conclusions Low-dose-rate brachytherapy can be used to treat lip carcinomas at Stages T1 and T2 as the only treatment with excellent results for local control and relapse-free survival. The benefits of brachytherapy are also cosmetic and functional, with 91% of patients having no side effects.

28 Background: To assess the effect of the timing of biochemical failure (bF) after definitive radiotherapy with external beam (EBRT) or low dose-rate brachytherapy (LDR) on clinical failure (cF) and prostate cancer-specific mortality (PCSM). Methods: From 1996 to 2009, 4478 patients were treated and by 2010, 456 patients were noted to have a bF. They were categorized as early (< 5 years post-therapy) or late (≥ 5 years post-therapy) failures. Factors thought to influence cF and PCSM were scored. Cox regression was used to assess the timing of bF on cF and Fine and Gray regression was used to assess the timing of bF on PCSM. Results: There were 330 (72.4 %) patients categorized as early and 126 (27.6 %) as late failures. The median PSA follow-up post-radiotherapy for the early bF group is 82 months vs. 155 months for the late bF group, and the median PSA follow-up post-bF is 54 months for the early bF group vs. 69 months for the late bF group. The early failures were more likely to be high-risk (p = 0.0080), have a higher Gleason score (p = 0.0008), and use ADT (p = 0.0325). The five-year rate of cF post early bF is 61% vs 43% post late bF (p

Purpose: Adjuvant high-dose-rate brachytherapy (HDRBT) offers advantages over low dose rate brachytherapy (LDRBT), although there are little data on local tumor control and treatment related toxicity. We report outcome in patients with primary, recurrent, and metastatic extremity and superficial trunk soft tissue sarcoma. Material and methods: Eleven patients (12 sites) with intermediate or high grade sarcoma were treated with adju vant HDRBT following surgical resection. Patients were treated at 3.4 Gy fractions delivered twice daily to a total dose of 34 Gy (1 patient received 9 fractions). Results: With median follow-up of 20.8 months, 1 patient developed a local recurrence. 2-year local control and overall survival are 89% and 71%, respectively. Wound complications occurred in 3 sites. Two of the wound complica tions developed in the area of previous external beam radiotherapy (EBRT). Conclusion: Surgical resection followed by HDRBT is associated with excellent early local tumor control and accept able wound complication. J Contemp Brachyther 2011; 3, 1: 3-10 DOI: 10.5114/jcb.2011.21036

A dose response exists when higher doses of radiation on a retrospective multi-institutional pooled data series (energy deposited per unit mass of tissue) delivered to cancer cells result in an increase in cell kill. Lower doses result in lower cell kill. In the laboratory, this is well documented by cell survival curves generated from in vitro experiments. In clinical practice, these relationships are usually demonstrated by correlating cancer control rates with various delivered radiation dose levels. In prostate cancer, a unique biochemical surrogate exists, prostatespecific antigen (PSA), which can be used to detect cancer recurrence at an early time frame. This endpoint has been used in the clinical setting to test the hypothesis of a dosee response relationship in the treatment of prostate cancer with external beam radiation therapy (EBRT). The data from both retrospective and randomized controlled EBRT trials clearly demonstrate an improvement in outcomes with increasing dose. A recent report of the long-term results of the M.D. Anderson Cancer Center randomized trial of dose escalation documented an improvement in freedom from biochemical failure of 78% for the dose arm of 78 Gy vs. 59% for the 70 Gy arm ( p5 0.004) (1). In another randomized trial, reported by Zeitman et al. (2), 70.2 Gy of conventional dose radiation was compared with 79.2 Gy delivered with combination of photons and protons. Freedom from biochemical failure was 78.8% at 5 years for the conventional arm vs. 91.3% for the high-dose arm ( p!0.001). Zelefsky et al. (3) reported improved biochemical relapse-free survival with increasing radiation dose. Fiveyear relapse-free survival was 71%, 66%, 61%, and 40% for doses of 86.4, 81, 75.6, and #70.2 Gy. In a randomized trial of the Medical Research Council (RT01), patients were randomized to 74 Gy in 37 fractions vs. 64 Gy in 32 fractions. The 5-year biochemical relapse-free survival was greater for the higher dose group (75% at 5 years) vs. 62% for the low-dose arm (4). Kupelian et al. (5) reported

Objective: To examine the rate of Gleason sum upgrading (GSU) from a sum of 6 to a Gleason sum of ≥7 in patients undergoing radical prostatectomy (RP), who fulfilled the recommendations for low dose rate brachytherapy (Gleason sum 6, prostate-specific antigen ≤10 ng/mL, clinical stage ≤T2a and prostate volume ≤50 mL), and to test the performance of an existing nomogram for prediction of GSU in this specific cohort of patients. Methods: The analysis focused on 414 patients, who fulfilled the European Society for Therapeutic Radiation and Oncology and American Brachytherapy Society criteria for low dose rate brachytherapy (LD-BT) and underwent a 10-core prostate biopsy followed by RP. The rate of GSU was tabulated and the ability of available clinical and pathological parameters for predicting GSU was tested. Finally, the performance of an existing GSU nomogram was explored. Results: The overall rate of GSU was 35.5%. When applied to LD-BT candidates, the existing nomogram was 65.8% accurate versus 70.8% for the new nomogram. In decision curve analysis tests, the new nomogram fared substantially better than the assumption that no patient is upgraded and better than the existing nomogram. Conclusions: GSU represents an important issue in LD-BT candidates. The new nomogram might improve patient selection for LD-BT and cancer control outcome by excluding patients with an elevated probability of GSU.

Purpose To retrospectively assess the physics contributions and the clinical outcome with preliminary 3D MRI-guided low dose-rate (LDR) intracavitary brachytherapy (BT) experience in locally advanced cervical cancer patients. Patients and methods Eighty-four patients with primary locally advanced cervical carcinoma were analyzed. The median tumoral cervical volume was 48.0cc (range 1–468cc). Twenty-four patients (53%) had histological and/or radiological pelvic involvement. After pelvic±paraaortic concomitant chemoradiation, a LDR BT boost was delivered to a 3D MRI-based clinical target volume taking into account dose volume constraints for critical organs and optimization of target volume coverage. Results With a median follow-up of 53months (range 31–79months), the 4-year overall survival and disease-free survival rates were 57 (95%CI, 43–69) and 52% (95%CI, 40–64), respectively. Adding EBRT and LDR using EQD2 model, the median D 100 and D 90 for the IR-CTV were 56.5Gy α / β 10 (range 37–83Gy α / β 10 ) and 69Gy α / β 10 (range 52–113Gy α / β 10 ), respectively. For HR-CTV, the median D 100 and D 90 were 67Gy α / β 10 (range 47–119Gy α / β 10 ) and 79Gy α / β 10 (range 53–122Gy α / β 10 ), respectively. Thirty-nine late complications were observed in 28 patients (33.3%): 13 bladder, 7 rectal, 5 small bowel, 4 urethral, 3 colic, 2 vaginal, 1 pelvic fibrosis, and 4 others. Four grade 3 delayed complications were observed and no grade 4 complication occurred. Conclusions Applying an individual treatment planning with 3D MRI-guided LDR brachytherapy appears to be feasible and efficient for patients with locally advanced cervical cancer in routine clinical practice.

Purpose To describe a novel technique that integrates customized sleeved seed production to reduce seed migration using preloaded needles with real-time intraoperative dosimetric planning for patients treated with iodine-125 (I-125) permanent prostate seed implants. Methods and Materials Customized seed-spacer sequences were calculated for patients in real time based on an intraoperative transrectal ultrasound-guided volume study. Using a Fox Chase Cancer Center modified Best Iodine-125 seed loader (Best Medical, Springfield, VA), the seeds and spacers were inserted into a hollow suture material (sleeve) and then loaded into the implant needles. Needles were placed sequentially under transrectal ultrasound guidance with sagittal plane visualization of the dropped sleeved seeds. Results This technique was successfully implemented allowing intraoperative planning to be combined with real-time sleeved seed production. Conclusions The use of sleeves for seeds combined with real-time intraoperative planning allowed for the intraoperative customization of implants with the practical advantages of linked seeds.

We assessed the impact of androgen suppressive therapy on biochemical failure in patients with intermediate risk prostate cancer treated with brachytherapy and external beam irradiation.From 1994 to 2006, 432 patients with intermediate risk prostate cancer as defined by the National Comprehensive Cancer Network were treated with low dose rate brachytherapy and external beam irradiation with or without 9 months of androgen suppressive therapy. Gleason score was 7 in 76% of cases and prostate specific antigen was 1.4 to 20 ng/ml (median 7.6). Of the patients 350 received androgen suppressive therapy and 82 did not. The biologically effective dose was 142 to 280 Gy2 (median 206). Followup was 23 to 155 months (median 56).The overall 8-year biochemical failure-free rate using the Phoenix definition in patients with vs without androgen suppressive therapy was 92% vs 92% (p = 0.4). The therapy had no significant impact on the biochemical failure-free rate in patients with Gleason score 7 (92% vs 90.5%, p = 0.55), prostate specific antigen 10 to 20 ng/ml (92% vs 100%, p = 0.32), T2b-T2c disease (89.5% vs 97%, p = 0.27) and more than 1 intermediate risk feature (90% vs 100%, p = 0.2).We addressed the relative importance of radiation dose vs hormonal therapy for intermediate risk prostate cancer. With high biologically effective dose combination treatment androgen suppressive therapy did not have a significant impact on the 8-year biochemical failure-free rate. We question its routine use in this setting.

Purpose: In order to know the effect of variation in position of applicators to the dose received by the tumor volume, critical organs such as rectum and bladder and the correlation of variation on the clinical outcome. Material and methods: 36 patients with histologically proven cervical cancer, undergoing intracavitary brachythe rapy (ICBT) from October 2005 to December 2006 were the subjects of the study. Two pairs of orthogonal X-ray films were taken: one prior to loading of sources and the other after removal of sources. These patients were followed up as per the RTOG criteria. Results: The median duration of insertion was 25 hours with a median follow up period of 6.7 months. The translational variation of the applicator position for all patients was 3 mm and 1 mm (2 SD), respectively, in the patient’s lateral and antero-posterior direction. The rotational variation was 3 and 4 degrees (2 SD) in the patient’s transverse and sagittal planes. Detailed analysis of source movement showed following changes in median dose: point A: 14%, point B: 2%, point P: 1%, Rectum 1: 3.5%, Rectum 2: 4% and Bladder: 9.1%. The incidence of rectal toxicity was 6/36 (16.7%) and that of bladder was 1/36 (2.8%). When the variables were grouped to evaluate the relationship, our study showed statistically significant relationship between: R2 and rectal toxicity (p value: 0.002), point A and rectal toxicity (Pearson: 0.792), lateral displacement/anteroposterior displacement and rectal toxicity (p value: 0.012/0.003), beta angle and R2 (p value: 0.002). Conclusions: The geometric relationships between the ICBT applicators and the critical structures vary during the course of low dose rate brachytherapy. Source movement does result in significant dose alterations in terms of increased rate of complications, but its impact on cure rates needs to be studied in the future. J Contemp Brachyther 2010; 2, 3: 93-97 DOI: 10.5114/jcb.2010.16919

Radical radiotherapy is one of the options for the management of prostate cancer. In external beam therapy, 3D conformal radiotherapy (3DCRT) and intensity modulated radiotherapy (IMRT) are the options for delivery of increased radiation dose, as vital organs are very close to the prostate and a higher dose to these structures leads to an increased toxicity. In brachytherapy, low dose rate brachytherapy with permanent implant of radioactive seeds and high dose rate brachytherapy (HDR) with remote after loaders are available. A dosimetric analysis has been made on IMRT and HDR brachytherapy plans. Ten cases from each IMRT and HDR brachytherapy have been taken for the study. The analysis includes comparison of conformity and homogeneity indices, D100, D95, D90, D80, D50, D10 and D5 of the target. For the organs at risk (OAR), namely rectum and bladder, V100, V90 and V50 are compared. In HDR brachytherapy, the doses to 1 cc and 0.1 cc of urethra have also been studied. Since a very high dose surrounds the source, the 300% dose volumes in the target and within the catheters are also studied in two plans, to estimate the actual volume of target receiving dose over 300%. This study shows that the prescribed dose covers 93 and 92% of the target volume in IMRT and HDR brachytherapy respectively. HDR brachytherapy delivers a much lesser dose to OAR, compared to the IMRT. For rectum, the V50 in IMRT is 34.0cc whilst it is 7.5cc in HDR brachytherapy. With the graphic optimization tool in HDR brachytherapy planning, the dose to urethra could be kept within 120% of the target dose. Hence it is concluded that HDR brachytherapy may be the choice of treatment for cancer of prostate in the early stage.

Background To our knowledge no DVH data have so far been reported for MRI-guided BT in the preoperative setting of early-stage cervical cancer. We assessed DVH parameters and clinical outcome using 3D MRI-guided preoperative intracavitary LDR BT. Patients and methods Thirty-nine patients with primary early cervical carcinoma (IB1 37, IIA 1 and IIB 1) were treated with preoperative MRI-based LDR BT, consisting of uterovaginal BT to a total dose of 60Gy to the intermediate-risk CTV, followed 6weeks later by bilateral salpingo-oophorectomy and extrafascial hysterectomy plus pelvic node dissection. Adjuvant chemoradiation was delivered to patients with pelvic lymph node involvement. Results With a median follow-up of 4.4years (range 2.6–6.6years), local recurrence occurred in 1 patient (a lateropelvic relapse) (2.6%). The 4-year actuarial overall survival and disease-free survival were 94% (95% CI, 82–98), and 86% (95% CI, 67–95), respectively. The 2- and 4-year actuarial local relapse-free survival were 94 (95% CI, 86–100) and 91% (95% CI, 81–100), respectively. For intermediate-risk CTV, median D 100 and D 90 were 43Gy α / β 10 (range 2–74Gy α / β 10 ) and 75Gy α/β 10 , respectively (range 29–129Gy α/β 10 ). For high-risk CTV, the median D 100 and D 90 were 69Gy α/β 10 (range 24–137Gy α/β 10 ) and 109Gy α/β 10 (range 37–198Gy α/β 10 ), respectively. Twenty grade 1–2 late complications were observed in 13 patients (33.3%): 10 bladder, 3 ureteral, 1 rectal, 1 small bowel, 1 vaginal, 1 pelvic fibrosis, 1 peripheral nerve, and 2 others. No grade 3 or 4 complication occurred. Conclusion MRI-guided brachytherapy with adaptation of the time duration and/or the length of each radioactive source allows both high local control and low toxicity in the preoperative settings of early-stage cervical cancers.

Purpose Low-dose-rate (LDR) brachytherapy is an integral treatment modality in radiation oncology. Clinical efficacy is based on experience with manual source loading and continuous dose delivery. With remote afterloading technology, sources may be loaded and unloaded during the treatment course to prevent radiation exposure to nursing staff members and visitors. The aim of this study was to investigate treatment interruptions in terms of frequency and duration as well as extension of the overall treatment time period. The potential clinical impact of treatment interruptions was also considered. Materials and Methods The treatment records of 20 patients who underwent brachytherapy in the Indiana University Department of Radiation Oncology administered with a Selectron LDR remote afterloader were reviewed. Results were tabulated and analysis performed with respect to 1) the number of interruptions, 2) delay time, 3) delay time ( T d ) as a function of total implant time ( T ), 4) the time of day that each interruption occurred, and 5) the time in minutes of each individual interruption. Results The mean number of interruptions was 44.9 per patient, (range, 24-76), with a mean prescription implantation duration of 45.7 hours and a mean actual treatment time of 51.2 hours resulting in a mean interruption time of 6.4 minutes per treatment hour. The number of interruptions was standardized and divided by the number of prescribed dose in grays, translating to 1.2 to 3.7 interruptions per gray delivered, with a mean of 1.6, resulting in an average T d of 11.21% (range, 7.35%-17.12%). Conclusion Significant interruptions are frequent using remote afterloading LDR techniques, reducing the effective dose rate. Careful monitoring of such interruptions is warranted.

Purpose: The low dose rate brachytherapy procedure would benefit from an intraoperative postimplant dosimetry verification technique to identify possible suboptimal dose coverage and suggest a potential reimplantation. The main objective of this project is to develop an efficient, operator-free, intraoperative seed detection technique using the imaging modalities available in a low dose rate brachytherapy treatment room. Methods: This intraoperative detection allows a complete dosimetry calculation that can be performed right after an I-125 prostate seed implantation, while the patient is still under anesthesia. To accomplish this, a digital tomosynthesis-based algorithm was developed. This automatic filtered reconstruction of the 3D volume requires seven projections acquired over a total angle of 60 deg. with an isocentric imaging system. Results: A phantom study was performed to validate the technique that was used in a retrospective clinical study involving 23 patients. In the patient study, the automatic tomosynthesis-based reconstruction yielded seed detection rates of 96.7% and 2.6% false positives. The seed localization error obtained with a phantom study is 0.4{+-}0.4 mm. The average time needed for reconstruction is below 1 min. The reconstruction algorithm also provides the seed orientation with an uncertainty of 10 deg. {+-}8 deg. The seed detection algorithm presented here ismore » reliable and was efficiently used in the clinic. Conclusions: When combined with an appropriate coregistration technique to identify the organs in the seed coordinate system, this algorithm will offer new possibilities for a next generation of clinical brachytherapy systems.« less

To evaluate the influence of patient- and treatment-related factors on freedom from biochemical failure (FFbF) in patients with intermediate-risk prostate cancer.From a prospectively collected database of 2250 men treated at Mount Sinai Hospital from 1990 to 2004 with low-dose-rate brachytherapy for prostate cancer, 558 men with either one or more intermediate-risk features (prostate-specific antigen [PSA] level 10-20 ng/mL, Gleason score 7, or Stage T2b) were identified who had a minimum follow-up of 24 months and postimplant CT-based dosimetric analysis. Biologically effective dose (BED) values were calculated to compare doses from different isotopes and treatment regimens. Patients were treated with brachytherapy with or without hormone therapy and/or external-beam radiotherapy. Patient- and treatment-related factors were analyzed with respect to FFbF. The median follow-up was 60 months (range, 24-167 months). Biochemical failure was defined according to the Phoenix definition. Univariate analyses were used to determine whether any variable was predictive of FFbF. A two-sided p value of0.05 was considered significant.Overall, the actuarial FFbF at 10 years was 86%. Dose (BED150 Gy(2) vs.or=150 Gy(2)) was the only significant predictor of FFbF (p0.001). None of the other variables (PSA, external-beam radiotherapy, Gleason score, treatment type, hormones, stage, and number of risk factors) was found to be a statistically significant predictor of 10-year FFbF.Radiation dose is an important predictor of FFbF in intermediate-risk prostate cancer. Treatment should continue to be individualized according to presenting disease characteristics until results from Radiation Therapy Oncology Group trial 0232 become available.

137Cs source in solid matrix encapsulated in stainless-steel at MBq (mCi) levels are widely used as brachytherapy sources for the treatment of carcinoma of cervix uteri. This article describes the large-scale preparation of such sources. The process of fabrication includes vitrification of 137Cs-sodium borosilicate glass, its transformation into spheres of 5-6 mm diameter, casting of glass spheres into a cylinder of 1.5 mm (varphi) x 80 mm (l) in a platinum mould, cutting of the moulds into 5-mm-long pieces, silver coating on the sources, and finally, encapsulation in stainless steel capsules. Development of safety precautions used to trap 137Cs escaping during borosilicate glass preparation is also described. The leach rates of the radioactive sources prepared by the above technology were within permissible limits, and the sources could be used for encapsulation in stainless steel capsules and supplied for brachytherapy applications. This development was aimed at promoting the potential utility of 137Cs-brachytherapy sources in the country and reducing the user's reliance on imported sources. Since its development, more than 1000 such sources have been made by using 4.66 TBq(126 Ci) of 137Cs.

A Monte Carlo (MC) study was carried out to evaluate the effects of the interseed attenuation and the tissue composition for two models of 125I low dose rate (LDR) brachytherapy seeds (Medi-Physics 6711, IBt InterSource) in a permanent breast implant. The effect of the tissue composition was investigated because the breast localization presents heterogeneities such as glandular and adipose tissue surrounded by air, lungs, and ribs. The absolute MC dose calculations were benchmarked by comparison to the absolute dose obtained from experimental results. Before modeling a clinical case of an implant in heterogeneous breast, the effects of the tissue composition and the interseed attenuation were studied in homogeneous phantoms. To investigate the tissue composition effect, the dose along the transverse axis of the two seed models were calculated and compared in different materials. For each seed model, three seeds sharing the same transverse axis were simulated to evaluate the interseed effect in water as a function of the distance from the seed. A clinical study of a permanent breast 125I implant for a single patient was carried out using four dose calculation techniques: (1) A TG-43 based calculation, (2) a full MC simulation with realistic tissues and seed models, (3) a MC simulation in water and modeled seeds, and (4) a MC simulation without modeling the seed geometry but with realistic tissues. In the latter, a phase space file corresponding to the particles emitted from the external surface of the seed is used at each seed location. The results were compared by calculating the relevant clinical metrics V85, V100, and V200 for this kind of treatment in the target. D90 and D50 were also determined to evaluate the differences in dose and compare the results to the studies published for permanent prostate seed implants in literature. The experimental results are in agreement with the MC absolute doses (within 5% for EBT Gafchromic film and within 7% for TLD-100). Important differences between the dose along the transverse axis of the seed in water and in adipose tissue are obtained (10% at 3.5 cm). The comparisons between the full MC and the TG-43 calculations show that there are no significant differences for V85 and V100. For V200, 8.4% difference is found coming mainly from the tissue composition effect. Larger differences (about 10.5% for the model 6711 seed and about 13% for the InterSource125) are determined for D90 and D50. These differences depend on the composition of the breast tissue modeled in the simulation. A variation in percentage by mass of the mammary gland and adipose tissue can cause important differences in the clinical dose metrics V200, D90, and D50. Even if the authors can conclude that clinically, the differences in V85, V100, and V200 are acceptable in comparison to the large variation in dose in the treated volume, this work demonstrates that the development of a MC treatment planning system for LDR brachytherapy will improve the dose determination in the treated region and consequently the dose-outcome relationship, especially for the skin toxicity.

UNLABELLED Low dose rate (LDR) brachytherapy is a well established treatment for the early stages of tongue cancer. High dose rate (HDR) afterloading devices have replaced LDR brachytherapy in many radiotherapy departments, but the effect and safety of HDR brachytherapy in comparison with LDR brachytherapy for interstitial applications is an unresolved question. The aim of our radiobiological study was to utilize dose volume histiograms from patients treated in our institution to simulate the risk of complication of LDR and HDR brachytherapy. Normal tissue complication probabilities (NTCP) of acute mucositis, late mucosal necrosis and osteoradionecrosis of two HDR brachytherapy schedules (18 x 3 Gy bid and 10 x 6 Gy bid) and of LDR brachytherapy with identical tumor control probability were compared using data from 8 brachytherapy applications. A linear quadratic (LQ) model was used to calculate the biologically equivalent doses, the effective volume method of Kutcher and Burman and Lyman's model was used to calculate NTCP. The Student's two-tailed test was used for statistical analysis. For 18 x 3 Gy bid the risk of acute mucositis and of late mucosal necrosis was 1.48 and 1.66 times higher with HDR in comparison with LDR brachytherapy. For 10 x 6 Gy bid the risk of acute mucositis, mucosal necrosis and osteoradionecrosis was 1.3, 3.44 and 13.18 times higher with HDR brachytherapy. All differences were statistically highly significant. Our radiobiological study supported the hypothesis that HDR has a higher risk of complication in comparison with LDR brachytherapy for the same tumor control probability. KEYWORDS tongue cancer, brachytherapy, low dose rate, high dose rate.