Postoperative Dosimetry Research Articles

Modeling the impact of prostate edema on LDR brachytherapy: a Monte Carlo dosimetry study based on a 3D biphasic finite element biomechanical model

Prostate volume changes due to edema occurrence during transperineal permanent brachytherapy should be taken under consideration to ensure optimal dose delivery. Available edema models, based on prostate volume observations, face several limitations. Therefore, patient-specific models need to be developed to accurately account for the impact of edema. In this study we present a biomechanical model developed to reproduce edema resolution patterns documented in the literature. Using the biphasic mixture theory and finite element analysis, the proposed model takes into consideration the mechanical properties of the pubic area tissues in the evolution of prostate edema. The model’s computed deformations are incorporated in a Monte Carlo simulation to investigate their effect on post-operative dosimetry. The comparison of Day1 and Day30 dosimetry results demonstrates the capability of the proposed model for patient-specific dosimetry improvements, considering the edema dynamics. The proposed model shows excellent ability to reproduce previously described edema resolution patterns and was validated based on previous findings. According to our results, for a prostate volume increase of 10–20% the Day30 urethra D10 dose metric is higher by 4.2%–10.5% compared to the Day1 value. The introduction of the edema dynamics in Day30 dosimetry shows a significant global dose overestimation identified on the conventional static Day30 dosimetry. In conclusion, the proposed edema biomechanical model can improve the treatment planning of transperineal permanent brachytherapy accounting for post-implant dose alterations during the planning procedure.

Dosimetric Evaluation of Iodine-125 Brachytherapy for Tumour Size < 5cm NSCLC Patients

To analysis domestry of target and important organs in I-125 brachytherapy for lung cancer. In this study, we review 7 patients of tumour size < 5cm non-small cell lung cancer (NSCLC) with I-125 brachytherapy. Post-operative dosimetry consists of a CT-based planning and dose volume analysis. Tumour volume, doses for tumour, dose distributions, dose volume histograms and mean dose data for lung are analysed in a group of patients. Tumour volums exchange before and after implantations, among which 5 are larger and 2 are smaller. Dosimetric results show high dose in tumour but significant lung sparing with only a small volume of lung irradiated for all patients with mean lung dose values ranging from 5.21Gy to 24.56Gy. I-125 brachytherapy provides a technique to treat a tumour with relatively small margins, rapid dose fall-off leading to improved lung sparing.

CT AND MRI FUSION FOR POSTIMPLANT PROSTATE BRACHYTHERAPY EVALUATION.

Postoperative evaluation of prostate brachytherapy is typically performed using CT, which does not have sufficient soft tissue contrast for accurate anatomy delineation. MR-CT fusion enables more accurate localization of both anatomy and implanted radioactive seeds, and hence, improves the accuracy of postoperative dosimetry. We propose a method for automatic registration of MR and CT images without a need for manual initialization. Our registration method employs a point-to-volume registration scheme during which localized seeds in the CT images, produced by commercial treatment planning systems as part of the standard of care, are rigidly registered to preprocessed MRI images. We tested our algorithm on ten patient data sets and achieved an overall registration error of 1.6 ± 0.8 mm with a running time of less than 20s. With high registration accuracy and computational speed, and no need for manual intervention, our method has the potential to be employed in clinical applications.

Permanent interstitial 125I seed implantation as a salvage therapy for pediatric recurrent or metastatic soft tissue sarcoma after multidisciplinary treatment.

BackgroundThe management of pediatric recurrent or metastatic soft tissue sarcoma after multimodal treatment remains challenging. We investigated the feasibility, efficacy, and morbidity of permanent interstitial 125I seed implantation under image guidance as a salvage treatment for pediatric patients with recurrent or metastatic soft tissue sarcoma.MethodsThis was a retrospective study of 10 patients who underwent percutaneous ultrasound or computed tomography (CT) guided permanent 125I seed implantation. Postoperative dosimetry was performed for all patients. Actuarial D90 was 121–187.1 Gy (median, 170.3 Gy). The number of 125I seeds implanted was 6–158 (median, 34.5), with a median specific activity of 0.7 mCi per seed (range, 0.62–0.8 mCi); total activity was 4.2–113.76 mCi. Follow-up time was 6–107 months (median, 27.5 months); no patients were lost to follow-up.ResultsThe overall response rate (complete response + partial response) was 8/10 (80 %), including two patients with complete response (CR) (20 %) and five patients with partial response (PR) (60 %). Local control rates after 1 and 2 years were 70.1 and 62.3 %, respectively, with a mean local control time of 70.6 months (95 % confidence interval (CI) 45.1–96.0). Survival rates after 1 and 2 years were 68.6 and 57.1 %, respectively, with a mean survival time of 65.3 months (95 % CI 34.1–96.5). Three patients died from distant metastasis; one died from local recurrence 12 months after seed implantation. Three patients suffered a grade I skin reaction and one developed ulceration. No severe adverse neurologic sequelae or blood vessel damage occurred.ConclusionsImage guided permanent interstitial 125I seed implantation as a salvage treatment appears to have a satisfactory outcome in children with recurrent or metastatic soft tissue sarcoma.

CT-Guided 125i Seed Implantation for In-Field Recurrence of NSCLC With Prior Radiation

PurposeTo assess the feasibility, efficacy, and morbidity of CT image-guided radioactive iodine 125 (125I) seed implantation for in-field recurrence of NSCLC with prior radiation.Materials and Methods14 patients received CT-guided percutaneous permanent implantation of 125I seeds for in-field recurrence of NSCLC between October 2010 and August 2014. All patients received radiotherapy before seed implantation. The tumor volumes were measured using CT scans at 5-mm intervals one week before seed implantation. Postoperative dosimetry was routinely performed for all patients. The D90 (the doses delivered to 90% of the target volume defined by CT using dose-volume histogram) of the implanted 125I seeds ranged from 83Gy to 224Gy (median: 111 Gy). The activity of 125I seeds ranged from 0.58mCi to 0.75mCi (median: 0.72mCi). The total number of seeds implanted ranged from 16 to 61 (median: 39). The survival and local control probabilities were calculated by the Kaplan-Meier method.ResultsThe median local control was 7months (95% CI, 4.26-9.74 months). The 1- and 2-year local control rates were 33.3%, and 33.3%, respectively. The estimate median overall survival is 18 months (95% CI, 11.91-24.09 months). The 1- and 2-year overall survival rates were 67.5%, 27.0% respectively. 71.4% of the symptoms (10/14) had disappeared or improved. No patients had radiation pneumonia, or radiation esophagitis in follow-up. One patient developed lethal hemoptysis 18 months after seed implantation.ConclusionsInterstitial permanent implantation of 125-I seeds under CT guidance is feasible, efficacy and safe method for in-field recurrence of NSCLC with prior radiation. PurposeTo assess the feasibility, efficacy, and morbidity of CT image-guided radioactive iodine 125 (125I) seed implantation for in-field recurrence of NSCLC with prior radiation. To assess the feasibility, efficacy, and morbidity of CT image-guided radioactive iodine 125 (125I) seed implantation for in-field recurrence of NSCLC with prior radiation. Materials and Methods14 patients received CT-guided percutaneous permanent implantation of 125I seeds for in-field recurrence of NSCLC between October 2010 and August 2014. All patients received radiotherapy before seed implantation. The tumor volumes were measured using CT scans at 5-mm intervals one week before seed implantation. Postoperative dosimetry was routinely performed for all patients. The D90 (the doses delivered to 90% of the target volume defined by CT using dose-volume histogram) of the implanted 125I seeds ranged from 83Gy to 224Gy (median: 111 Gy). The activity of 125I seeds ranged from 0.58mCi to 0.75mCi (median: 0.72mCi). The total number of seeds implanted ranged from 16 to 61 (median: 39). The survival and local control probabilities were calculated by the Kaplan-Meier method. 14 patients received CT-guided percutaneous permanent implantation of 125I seeds for in-field recurrence of NSCLC between October 2010 and August 2014. All patients received radiotherapy before seed implantation. The tumor volumes were measured using CT scans at 5-mm intervals one week before seed implantation. Postoperative dosimetry was routinely performed for all patients. The D90 (the doses delivered to 90% of the target volume defined by CT using dose-volume histogram) of the implanted 125I seeds ranged from 83Gy to 224Gy (median: 111 Gy). The activity of 125I seeds ranged from 0.58mCi to 0.75mCi (median: 0.72mCi). The total number of seeds implanted ranged from 16 to 61 (median: 39). The survival and local control probabilities were calculated by the Kaplan-Meier method. ResultsThe median local control was 7months (95% CI, 4.26-9.74 months). The 1- and 2-year local control rates were 33.3%, and 33.3%, respectively. The estimate median overall survival is 18 months (95% CI, 11.91-24.09 months). The 1- and 2-year overall survival rates were 67.5%, 27.0% respectively. 71.4% of the symptoms (10/14) had disappeared or improved. No patients had radiation pneumonia, or radiation esophagitis in follow-up. One patient developed lethal hemoptysis 18 months after seed implantation. The median local control was 7months (95% CI, 4.26-9.74 months). The 1- and 2-year local control rates were 33.3%, and 33.3%, respectively. The estimate median overall survival is 18 months (95% CI, 11.91-24.09 months). The 1- and 2-year overall survival rates were 67.5%, 27.0% respectively. 71.4% of the symptoms (10/14) had disappeared or improved. No patients had radiation pneumonia, or radiation esophagitis in follow-up. One patient developed lethal hemoptysis 18 months after seed implantation. ConclusionsInterstitial permanent implantation of 125-I seeds under CT guidance is feasible, efficacy and safe method for in-field recurrence of NSCLC with prior radiation. Interstitial permanent implantation of 125-I seeds under CT guidance is feasible, efficacy and safe method for in-field recurrence of NSCLC with prior radiation.

Computed Tomography (CT)-guided Interstitial Permanent Implantation of 125I Seeds for Refractory Chest Wall Metastasis or Recurrence

To evaluate the efficacy and safety of 125I seeds implantation for refractory chest wall (CW) metastasis or recurrence under CT guidance. In addition we assessed initial data obtained on the therapeutic response for refractory CW metastasis or recurrence. Twenty consecutive patients underwent permanent implantation of 125I seeds (from Jul. 2004 to Jan. 2011) under computed tomography (CT) guidance. Postoperative dosimetry was routinely performed for all patients. The actuarial D90 of the implanted 125I seeds ranged from 100 Gy to 160 Gy (median: 130 Gy). The activity of 125I seeds ranged from 0.5 mCi to 0.78 mCi (median: 0.71 mCi). The total number of seeds implanted ranged from 8 to 269 (median: 53). The follow-up period ranged from 3 to 54 months (median: 11.5 months). The survival and local control probabilities were calculated by the Kaplan-Meier method. Among all the 20 patients, 3 patients had complete remission CR (15%), 12 patients had partial remission PR (60%), 5 patients had stable disease SD. The 1-, 2-, 3- and 4-year tumor control rates were all 88.7% respectively. The 1- and 2-, 3-, 4-year cancer specific survival rates were 56.5% and 47.1%, 47.1%, 47.1% respectively. The 1- and 2-, 3-, 4-year overall survival rates were 53.3% and 35.6%, 35.6%, 35.6% respectively, with a median survival of 15 months (95% CI, 7.0-22.9). Mild brachial plexus injury was seen in one patient; grade 1 or 2 skin reactions were seen in 6 patients (30%) who had received external beam radiation therapy (EBRT) before. No grade 3 and 4 skin side effects were found. Rib fracture, ulceration, pneumothorax or hemopneumothorax were not seen. Interstitial permanent implantation of 125I seeds under CT guidance is feasible, efficacious and safe for refractory CW metastasis or recurrence.

Loose versus stranded seeds in permanent prostate brachytherapy: Dosimetric comparison of intraoperative plans

PurposeTo compare target volume coverage and critical organ dosimetry of intraoperative treatment plans for loose seed (LS) and stranded seed (SS) 125I permanent implants for low and intermediate risk prostate cancer. MethodsTwo hundred and five patients who underwent permanent seed brachytherapy were included in the study. For prostate dosimetry V90, V100, V150, V200, D90 and COIN were used. The dose to urethra and rectum was determined by the maximal dose and relative doses that cover specified volumes. Means and standard deviations were calculated and statistically compared. ResultsOn average, 54 (range, 30–78) and 48 (range, 31–67) seeds were implanted in the prostate with individual median activities of 0.62 U (range, 0.52–0.70 U) and 0.71 U (range, 0.65–0.71 U) for LS and SS technique, respectively. The target coverage was slightly better with SS (V100: 98% vs. 96%,p < 0.05; D90: 172 Gy vs. 166 Gy, p < 0.05), but more conformal dose distributions were observed with LS (COIN: 0.70 vs. 0.63, p < 0.05). The dose homogeneity did not differ significantly between the two groups. Regarding the dose to urethra and rectum all dose parameters were significantly lower with LS. ConclusionsLS resulted in less dose to the urethra and rectum compared to SS in intraoperative dosimetry. A slightly better target volume coverage with decreased conformity of dose distribution is reported with SS. More studies are necessary to determine how these results will affect postoperative dosimetry, and ultimately, clinical outcome.

The difference in implantation quality between loose seed and variable spacing strand seeds in the field of prostate brachytherapy.

252 Background: Concordance between intraoperative and postoperative dosimetry is a well-known marker of implant quality in prostate brachytherapy. The aim of the study was to evaluate if the use of variable distance strand seeds allows an improvement in the quality of the post implantation dosimetry. Methods: Before December 2010, an iodine 125 loose-seed technique was used for prostate brachytherapy. Since this date, patients have been treated with new variable distance strand seeds (ProLink; Bard). Post implant dosimetry was compared to intraoperative dosimetry in 30 patients treated with loose seeds and 29 patients treated with strand seeds. The prescribed dose was 145Gy. Variations of dosimetric parameters were used to set the two techniques against one another: prostate V100 and D90 and rectum V145 and V160. Results: There was a significant difference between intraoperative and postoperative V100 and D90 for all 59 patients: V100 preop-postop: mean 6,65% +/- SD 4,5; D90 preop-postop: 18,73Gy +/- SD 15 (p&lt;0,0001). This dosimetric difference between pre and post-operative dosimetry is more important using loose seeds brachytherapy: V100 preop-postop: 9,5% +/- SD 4,1 vs 3,7% +/- SD 2,7 for loose seeds and strand seeds respectively (p&lt;0,0001), and D90 preop-postop: 27,9Gy +/-SD 13,6 vs 9,2Gy +/- SD 9,7 for loose seeds and strand seeds respectively (p&lt;0,0001). For V145 rectum and V160 rectum, dosimetric difference wasn't significant: V145 rectum preop-postop: -0,9% +/- SD 1,4 with stranded seeds vs. -1,6% +/- SD 2,1 with loose seeds (p=0,14) and V160 rectum pre-postop: -0,5% +/- SD 0,8 with strand seeds vs. -0,5% +/- SD 0,8 with loose seeds (p=0,16). Conclusions: Stranded seeds implantation increases the quality of implantation by reducing the dosimetric difference (V100 and D90) between intra and post-operative dosimetry to a maximum of 6% and 7% vs. more than 20% with loose seed implantation. Moreover, this technique doesn’t seem to modify the risk of rectal toxicity. This achievement in implantation and dosimetric quality might lead to a gain in clinical results.

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 (131Cs). Between 2006 and 2010, 166 patients implanted with 131Cs 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.

Re-implantation after insufficient primary 125-i permanent prostate brachytherapy

IntroductionWe describe five patients receiving a re-implantation (RI) after post-operative dosimetry of the primary 125-I permanent prostate brachytherapy (BT) for prostate cancer revealed an insufficient dose coverage.Materials and methodsFive out of 222 consecutive patients treated (from March, 2001 to August, 2012) with 125-I BT, received a RI after dosimetric verification by CT and MRI fusion four to eight weeks after implantation displayed an insufficient dose coverage. RIs were performed with 10 to 19 seeds, three to four months after primary intervention. Dosimetry after RI showed an improved and sufficient total dose coverage in all patients.ResultsAt last follow-up (18 to 99 months, median 57 months), none of the patients had relevant implant associated side-effects. Functional outcome was comparable to patients after one-time implantation. PSA levels post intervention showed a decreasing tendency in 4 patients. One patient had a local recurrence after 12 months.ConclusionIn our series, approximately 2% of the patients treated with permanent prostate BT required a RI due to insufficient dose coverage. None of the patients who underwent RI experienced complications. Our series, although only with 5 cases and limited follow-up, along with other published reports, demonstrates good tolerability.

Comparison of low and intermediate source strengths for 125I prostate brachytherapy implants

To compare the implant quality and clinical outcomes for patients treated with low and intermediate strength (125)I seeds in prostate brachytherapy implants. This retrospective review included 390 consecutive patients treated with prostate brachytherapy from 1999 to 2006. The first 142 patients were implanted with source strengths lower than 0.415U (0.327mCi), with the subsequent 248 patients implanted with source strengths higher than 0.493U (0.388mCi). Clinical, dosimetric, toxicity, and outcome data were compared between these two cohorts of patients. Despite having similar prostate volumes, fewer sources (median, 95 vs. 113; p<0.0001) and fewer needles (median, 23 vs. 29; p<0.0001) were implanted in the intermediate strength cohort. The postimplant dosimetry demonstrated better quality implants in patients treated with intermediate strength sources (median D90, 160.0Gy vs. 139.6Gy; p<0.0001), with greater dose inhomogeneity identified in the intermediate strength cohort of patients. A higher incidence of late rectal toxicity was identified in patients treated with intermediate strength sources despite lower rectal doses in this cohort. The biochemical relapse-free survival, prostate cancer survival, and overall survival were not significantly different between the two cohorts. The transition from low to intermediate strength sources has led to fewer resources being used and improved postoperative dosimetry. Although there were more rectal complications identified in the intermediate strength cohort of patients in this analysis, there were no other significantly worse clinical or biochemical outcomes for patients implanted with intermediate strength sources.

Re-Implantation Following Suboptimal Dosimetry in Low-Dose-Rate Prostate Brachytherapy: Technique for Outpatient Source Insertion Using Local Anesthesia

Permanent low-dose-rate (LDR) brachytherapy for prostate adenocarcinoma is an effective treatment technique, but the risk of recurrence is dependent upon achievement of adequate dosimetric outcomes. Despite ample evidence that inadequate dosimetry leads to increased risk for cancer recurrence, there are few reports regarding the appropriate management of patients who are observed to have suboptimal dosimetry following initial implantation. We describe our method and results for improvement of post-operative dosimetry using targeted seed placement under local anesthesia within a clinic setting to improve final dosimetric outcomes.

First report on the use of a thinner 125I radioactive seed within 20-gauge needles for permanent radioactive seed prostate brachytherapy: Evaluation of postimplant dosimetry and acute toxicity

To compare postoperative dosimetry and acute toxicity of new 0.5-mm (125)I seeds in 20-gauge (20G) diameter prostate brachytherapy (PB) needles with standard 0.8-mm seeds in 18G needles. Postoperative dosimetry was performed on 100 consecutive PB patients treated with ThinSeeds in 20G needles and compared with 100 consecutively treated PB patients using standard-sized seeds and needles (18G). Dosimetry was performed on postoperative Day 1 CT scans. Acute urinary retention was also compared between these two groups. Acute toxicity was evaluated in 22 consecutively treated patients with thinner seeds/needles and compared with 22 consecutive concurrent patients treated with standard seeds and needles. All patients were evaluated by pre- and post-PB self-administered surveys, physical examinations on post-PB Day 1, and telephone surveys on Day 7. Endpoints included dysuria, acute urinary retention, hematuria, perineal pain/bruising, and International Prostate Symptom Score. Post-PB dosimetric comparison demonstrated that the V100 (95% vs. 91%), D90 (161Gy vs.149Gy), V150 (55% vs. 45%), and RV100 (0.43cc vs. 0.30cc) were significantly (p<0.0004) higher in the 20G group. Urinary retention rates were 8% and 7% and median catheter-dependent durations were 7 and 14 days for the 20G and 18G groups, respectively. No significant differences were found for dysuria, hematuria, or International Prostate Symptom Score. Post-PB Day 1 perineal bruising and pain scores on Days 1 and 7 were significantly less (p<0.04) in 20G cohort. Smaller diameter needles and seeds resulted in improved post-PB Day 1 V100 and D90 dosimetry, and significantly less acute perineal pain and bruising.

Impact of urinary catheterization on dosimetry after prostate implant brachytherapy with palladium-103 or iodine-125

Purpose Postoperative dosimetry is integral to quality assurance for prostate brachytherapy. Images on Day 0 are typically obtained with a contrast-filled urinary catheter in place for urethral dose calculations. However, expansion of the urethra and perhaps the prostate by the catheter may affect target coverage. We assessed the effect of urinary catheterization on target dosimetry after implantation with palladium-103 ( 103Pd) or iodine-125 ( 125I) seeds. Methods and Materials Patients were 29 consecutive men with postimplant dosimetry calculated with and without a urinary catheter after brachytherapy seed implantation; 19 patients received 103Pd seeds and 10 patients received 125I seeds. In each case, 14-French caude tip urinary catheters were placed before implantation, and axial CT slices of the pelvis were obtained before and after catheter removal for postimplant dosimetry. Dosimetric parameters were measured and compared with paired Student’s t tests. Trends were assessed by linear regression with the Pearson correlation coefficient. Results Removal of the urinary catheter significantly improved V 100 and D 90 for 103Pd implants (mean ± standard deviation (SD), 2.7% ± 4.2%; range, −0.4% to 15%; p = 0.011 and mean ± SD, 4.0% ± 3.4%; range, −0.1% to 13.8%; p < 0.01, respectively). For 125I implants, catheter removal improved D 90 (mean ± SD, 1.5% ± 1.8%; range, −1.3% to 4.2%; p = 0.027). For the 103Pd group, the magnitude of change in V 100 correlated with prostate size ( R 2 = 0.16) and source number ( R 2 = 0.15). Conclusions Urinary catheterization can artificially reduce target coverage after prostate implant brachytherapy. The patients undergoing 103Pd implantation with smaller (<30 cm 3) prostates and fewer (<90) sources are particularly susceptible to reduced D 90 and V 100 when a urinary catheter is present.

An analysis of intraoperative versus post-operative dosimetry with CT, CT–MRI fusion and XMR for the evaluation of permanent prostate brachytherapy implants

Background and purpose To assess the agreement between intraoperative and post-operative dosimetry and to identify factors that influence dose calculations of prostate brachytherapy implants. Materials and methods Patients treated with prostate brachytherapy implants underwent post-operative CT and XMR (combined X-ray and MR) imaging. Dose–volume histograms were calculated from CT, XMR and CT–MR fusion data and compared with intraoperative values for two observers. Multiple linear regression models assessed the influences of intraoperative D90, gland oedema, gland volume, source loss and migration, and implanted activity/volume prostate on post-operative D90. Results Forty-nine patients were studied. The mean D90 differences (95% confidence limits) between intraoperative and post-operative CT, XMR and CT–MR fusion assessments were: 11 Gy (−22, 45), 18 Gy (−13, 49) and 20 Gy (−17, 58) for Observer 1; and 15 Gy (−34, 63), 13 Gy (−29, 55) and 14 Gy (−27, 54) for Observer 2. Multiple linear regression modelling showed that the observed oedema and intraoperative D90 were significant independent variables for the prediction of post-operative D90 values for both observers using all modalities. Conclusion This is the first study to report Bland–Altman agreement analysis between intraoperative and post-operative dosimetry. Agreement is poor. Post-operative dosimetry is dependent on the intraoperative D90 and the subjectively outlined gland volume.

Percutaneous computed tomography/ultrasonography-guided permanent iodine-125 implantation as salvage therapy for recurrent squamous cell cancers of head and neck

Objective: To assess the feasibility, efficacy, and morbidity of permanent percutaneous 125I seed implantation under computed tomography (CT)/ultrasonography guidance for recurrent squamous cell carcinomas of head and neck. Methods: Twenty-five patients underwent 125I seed implantation under CT or ultrasonography guidance. Postoperative dosimetry was routinely performed for all the patients. The actuarial D90 of the implanted 125I seeds ranged from 90 Gy to 160 Gy (median: 130 Gy). The activity of 125I seed ranged from 0.35 mCi to 0.8 mCi (median: 0.6 mCi). The total number of seeds implanted ranged from 3 to 61 (median: 22). The follow-up period ranged from 3 to 40 months (median: 8 months). Results: The median local disease-free progression was 12 months (95% CI, 4.8–19.2), and the 1- and 2-year local tumor control rates were 48.7% and 39.9%, respectively. The 1- and 2-year survival rates were 42.5% and 28.3%, respectively (median: 11 months) (95% CI, 8.2–13.8). Of the 25 patients, 6 (24%) died of local recurrence and 5 (20%) died of metastases; 2 patients showed recurrences at 3 and 8 months after seed implantation and subsequently died of pneumonia. One patient died of heart disease. One developed ulceration with tumor progression. Blood vessel damage and neuropathy were not observed.Conclusion: The high local tumor control rates, minimal invasion, and low morbidity suggest that percutaneous 125I seed implantation is a feasible and safe salvage for patients with recurrent squamous cell carcinomas of the head and neck.

Intraoperative seed placement for thoracic malignancy—A review of technique, indications, and published literature

Purpose This review examines the role of permanent radioactive seed implantation in thoracic malignancy. This technique can be used intraoperatively to provide additional highly localized radiation therapy in cases where optimal oncologic margins are unattainable or to palliate unresectable disease. Methods and materials Relevant trials were identified through a systematic literature search using Pubmed. Results The intraoperative placement of brachytherapy seeds has been described after sublobar resection for non–small-cell lung cancer (NSCLC), where surgical margins are close or microscopically positive and in the presence of macroscopic residual disease. This brachytherapy technique is currently the focus of a randomized prospective trial in the USA in patients unfit for lobectomy for early-stage NSCLC. Conclusions This review summarizes the methods of brachytherapy seed placement and the published experience of brachytherapy implants within the thorax, also examining radiation safety and postoperative dosimetry. This technique has the potential to improve local control with optimal sparing of normal tissue owing to its highly conformal radiotherapy delivery.

Comparison between Real-time Intra-operative Ultrasound-based Dosimetry and CT-based Dosimetry for Prostate Brachytherapy Using Cesium-131

The purpose of this study was to evaluate the correlation between real-time intra-operative ultrasound-based dosimetry (USD) and day 0 post-implant CT dosimetry (CTD) (131)Cs permanent prostate brachytherapy. Fifty-two consecutive patients who underwent prostate brachytherapy with (131)Cs were evaluated. Real time operating room planning was performed using VariSeed 7.1 software. Post-needle placement prostate volume was used for real-time planning. Targets for dosimetry were D(90) >110%, V(100) >90%, V(150) <50%, and V(200) <20%. The CT scan for post-operative dosimetry was obtained on day 0. The mean values for USD, CTD, and the linear correlation, respectively, were, for D(90): 114.0%, 105.61%, and 0.15; for V(100): 95.1%, 91.6%, and 0.22; for V(150): 51.5%, 46.4%, and 0.40; and for V(200): 15.8%, 17.9%, and 0.42. The differences between the mean values for USD and CTD for D(90) (p<0.01), V(100) (p<0.01), and V(150) (p<0.05) were statistically significant. For D(90), 30.8% of patients had a >15% difference between USD and CTD and 51.9% of patients had a >10% difference between these values. In contrast, the USD and CTD for V(100) were within 5% in 55.8% of patients and within 10% in 86.5% of patients. This study demonstrates a correlation between the mean intra-operative USD and post-implant day 0 CTD values only for V(200). Significant variation in D(90), V(150), and V(200) values existed for individual patients between USD and CTD. These results suggest that real-time intra-operative USD does not serve as a surrogate for post-operative CTD, and that post-operative CTD is still necessary.

Prostate Brachytherapy After Ileal Pouch–Anal Anastomosis Reconstruction

To determine the safety of prostate brachytherapy in patients with clinically localized prostate cancer who have undergone proctocolectomy with ileal pouch-anal anastomosis (IPAA). We performed a retrospective chart review of patients with a prior history of IPAA reconstruction who underwent prostate brachytherapy at our institution. Clinical records were reviewed for demographic characteristics, postoperative dosimetry, changes in bowel function, and oncologic outcomes. Data were analyzed using descriptive statistics. Five patients with an IPAA underwent prostate brachytherapy for clinically localized prostate cancer. Mean time from colorectal reconstruction to prostate brachytherapy was 6.3 years. Adequate dosimetry (mean D90 114.9%, mean V100 91.1%, mean R100 0.76 mL) was achieved in each patient. Bowel frequency worsened in the immediate postoperative period in all patients, but all patients returned to their baseline bowel pattern by 4 months after their procedure. Serious complications, such as J-pouch ulcers, fistulas, or fecal incontinence, did not occur in these patients. Prostate brachytherapy is a safe treatment option in patients with clinically localized prostate cancer and a history of proctocolectomy and IPAA reconstruction.

Dosimetric and technical aspects of intraoperative I-125 brachytherapy for stage I non-small cell lung cancer

Initial treatment outcome data from our institution for stage I non-small cell lung cancer (NSCLC) patients have shown that sublobar resection in combination with iodine-125 (I-125) brachytherapy is associated with recurrence rates of 2.0%, compared to 18.6% with sublobar resection alone. In this work, the technical and dosimetric aspects required to execute this procedure from the radiation oncology perspective as well as an analysis of the dose distributions of patients treated with this technique are presented. In this treatment technique, I-125 seeds in vicryl suture are embedded into vicryl mesh and surgically inserted providing a 2.0 cm margin on each side of the resection staple line. A nomogram is developed to determine the suture spacing in the vicryl mesh, as a function of seed activity in order to deliver 120 Gy at a distance of 0.5 cm above and below the seed array. Post-operative dosimetry consists of a CT-based planning and dose volume analysis. Dose distributions, dose volume histograms and mean dose data for lung are analysed in a group of patients. Dosimetric results show significant lung sparing with only a small volume of lung irradiated for all patients with mean lung dose values ranging from 1.5 Gy to 5.4 Gy. Lung brachytherapy with I-125 at the time of sublobar resection is a highly conformal option of dose delivery for stage I NSCLC patients with compromised physiologic reserve. Patient-related toxicity clinically measured by loss of pulmonary function and radiation-induced pneumonitis have not been linked to this procedure.