Permanent interstitial implantation using palladium-103: the New York Medical College preliminary experience

The production of radionuclides for nuclear medicine from a compact, low-energy accelerator system

INTRODUCTION

The field of nuclear medicine is reliant on radionuclides for medical imaging procedures and radioimmunotherapy (RIT). The recent shut-downs of key radionuclide producers have highlighted the fragility of the current radionuclide supply network, however. To ensure that nuclear medicine can continue to grow, adding new diagnostic and therapy options to healthcare, novel and reliable production methods are required. Siemens are developing a low-energy, high-current - up to 10 MeV and 1 mA respectively - accelerator. The capability of this low-cost, compact system for radionuclide production, for use in nuclear medicine procedures, has been considered.

METHODOLOGY

The production of three medically important radionuclides - (89)Zr, (64)Cu, and (103)Pd - has been considered, via the (89)Y(p,n), (64)Ni(p,n) and (103)Rh(p,n) reactions, respectively. Theoretical cross-sections were generated using TALYS and compared to experimental data available from EXFOR. Stopping power values generated by SRIM have been used, with the TALYS-generated excitation functions, to calculate potential yields and isotopic purity in different irradiation regimes.

RESULTS

The TALYS excitation functions were found to have a good agreement with the experimental data available from the EXFOR database. It was found that both (89)Zr and (64)Cu could be produced with high isotopic purity (over 99%), with activity yields suitable for medical diagnostics and therapy, at a proton energy of 10MeV. At 10MeV, the irradiation of (103)Rh produced appreciable quantities of (102)Pd, reducing the isotopic purity. A reduction in beam energy to 9.5MeV increased the radioisotopic purity to 99% with only a small reduction in activity yield.

CONCLUSION

This work demonstrates that the low-energy, compact accelerator system under development by Siemens would be capable of providing sufficient quantities of (89)Zr, (64)Cu, and (103)Pd for use in medical diagnostics and therapy. It is suggested that the system could be used to produce many other isotopes currently useful to nuclear medicine.

Electroplating/electrodissolution/recovery cycle for rhodium target used for an industrial scale cyclotron production of palladium-l03

Electrodeposition of rhodium metal on a copper backing was performed in acidic sulfate media using RhCl3 · 3 H2O, Rh2(SO4)3 (recovered from hydrochloric acid solution) and also the commercially available Rhodex plating baths. This work describes the development of a high current density (2.4 A·cm-2) electrodissolution system that allows solubilisation of rhodium fragments, powder and pieces of foils and wires in the presence of hydrochloric and chlorine gas. Solvent-solvent extraction of no-carrier-added 103Pd from the irradiated rhodium target with a-furyldioxime into chloroform under the influence of hydrochloric acid concentration was investigated. The extraction yield was 85.3% for a single extraction with 0.37 M HCl, and 103Pd was more than 99% pure.

Monte Carlo dosimetric characterization of the IsoAid ADVANTAGE 103Pd brachytherapy source

For roughly 25 years, 125I and 103Pd sources have been used in the treatment of various malignant diseases such as prostate cancer. Various new sources have been marketed and produced to meet the demand for new sources to use in treatment. Recently, IsoAID LLC created the ADVANTAGE 103Pd source. Various dosimetric parameters must be determined to facilitate treatment planning using this source. Theoretical determination of dosimetric characteristics, dose rate constant, radial dose function, and anisotropy function for this new source followed the American Association of Physicists in Medicine (AAPM) Task Group 43U1 recommendations. Theoretical calculations were performed in liquid water using the PTRAN Monte Carlo code version 7.44. The radial dose function of the new source was calculated in liquid water at distances up to 10.0 cm, and the anisotropy function, at distances ranging from 0.5 cm to 7.0 cm. The anisotropy factors and anisotropy constant were derived from the anisotropy function. The results in water indicate that the dose rate constant is 0.709 +/- 0.014 cGy x h-1 x U-1 and that the anisotropy constant is 0.880 +/- 0.040. The dosimetric characteristics of this new source compare favorably with those of other commercially available 103Pd sources.

Customized conformal high-dose-rate brachytherapy boost for limited-volume nasopharyngeal cancer

PURPOSE

To determine the feasibility of and patient outcomes using customized high-dose-rate (HDR) brachytherapy to boost the nasopharynx after external beam radiation therapy (EBRT) in patients with carcinoma of the nasopharynx.

METHODS AND MATERIALS

Patients with nonmetastatic squamous cell carcinoma of the nasopharynx were treated using EBRT followed by a HDR brachytherapy boost delivered via customized catheters in a noninvasive, accurate, and reproducible method under direct fiber-optic visualization. Local control (LC), disease-free survival (DFS), and overall survival (OS) were analyzed. We also measured the change in maximum oral aperture as an indication of temporomandibular joint dysfunction.

RESULTS

Between March 1996 and July 2003, we treated 38 patients with this customized brachytherapy method. The procedure was well tolerated without any incidents of soft-tissue or bone necrosis and with minimal decrease of oral aperture. Median follow-up time was 47 months (range, 2-84 months); 35 patients had at least 1 year of follow-up. The 5-year actuarial rate of LC, DFS, and OS were 96.0%, 81.4%, and 92.7%, respectively.

CONCLUSIONS

The treatment has been well tolerated by all patients. The combination of conformal EBRT with our customized HDR brachytherapy boost has resulted in excellent local control to date, while minimizing temporomandibular joint dysfunction.

Dosimetric characteristics of the new RadioCoil™ Pd103 wire line source for use in permanent brachytherapy implants

Recently, a novel linear brachytherapy source in the form of a coiled wire has become available for use in interstitial implants of various treatment sites such as prostate gland. This source type employs a design completely different from that of most "seed" sources currently on the market, one which improves upon or eliminates several common problems with such sources. Dosimetric characteristics of these sources with active lengths 0.5 cm to 5.0 cm were determined for clinical application. For 0.5 cm and 1.0 cm active length sources, the dose rate constant, radial dose function, and two-dimensional (2D) anisotropy function were experimentally and theoretically determined following the updated AAPM Task Group 43 (TG-43U1) recommendations. Radial dose functions and/or "along-away" matrix functions were also obtained for sources with active lengths 2.0 cm to 5.0 cm. Measurements were performed with LiF thermoluminescent dosimeters in Solid Water phantoms. Measured data was compared to Monte Carlo simulated data in Solid Water utilizing the PTRAN code, version 7.43. After finding the data to be in agreement, Monte Carlo calculations were performed in liquid water to obtain clinically applicable dosimetric data as per TG-43U1 recommendations. The results indicated the dose rate constant of the 0.5 cm long RadioCoil 103Pd source in Solid Water to be 0.641 cGy h(-1) U(-1) when measured, and 0.636 cGy h(-1) U(-1) when simulated by Monte Carlo. The calculated dose rate constant in liquid water was found to be 0.650 cGy h(-1) U(-1). These values are comparable to other commercially available sources. Complete dosimetric data and simulation results are described in this paper. Per TG-43U1, clinical treatment planning systems should utilize the values reported for liquid water.

Theoretical and experimental determination of dosimetric characteristics for brachyseed Pd-103, model Pd-1, source

Dosimetric characteristics of the BrachySeed Pd-103, Model Pd-1 source have been determined using both theoretical and experimental methods. Dose rate constant, radial dose function, and anisotropy functions of the source have been obtained following the TG-43 recommendations. Derivation of the dose rate constant was based on recent NIST WAFAC calibration performed in accordance with their 1999 Standard. Measurements were performed in Solid Water using LiF TLD chips. Theoretical simulation calculations were performed in both Solid Water and water phantom materials using MCNP4C2 Monte Carlo code using DLC-200 interaction data. The results of the Monte Carlo simulation indicated a dose rate constant of 0.65 cGyh(-1)U(-1) and 0.61 cGyh (-1)U(-1) in water and Solid Water, respectively. The measured dose rate constant in Solid Water was found to be 0.63+/-7% cGyh (-1)U(-1), which is within the experimental uncertainty of the Monte-Carlo simulated results. The anisotropy functions of the source were calculated in both water and in Solid Water at the radial distances of 1 to 7 cm. Measurements were made in Solid Water at distances of 2, 3, 5, and 7 cm. The Monte-Carlo calculated anisotropy constant of the new source was found to be 0.98 in water. The tabulated data and 5th order polynomial fit coefficients for the radial dose function along with the dose rate constant and anisotropy functions are provided to support clinical use of this source.

Preparation of 103Pd seed-molecular plating of 103Pd onto silver rod

A method for 103Pd "molecular plating" onto the surface of a silver rod is reported. The optimal composition of the plating bath is as follows: palladium chloride 0.1 mol/l, formaldehyde 2 mol/l, nitric acid 1 mol/l, and formic acid 0.4 mol/l. The 103Pd molecular plating procedure will last 25 min at 30 degrees C. This article provides a valuable experience for the preparation of 103Pd brachytherapy seed.

Experimental and theoretical determination of dosimetric characteristics of IsoAid ADVANTAGE 125I brachytherapy source

125I brachytherapy sources are being used for interstitial implants in tumor sites such as the prostate. Recently, the ADVANTAGE 125I, Model IAI-125, source became commercially available for interstitial brachytherapy treatment. Dosimetric characteristics (dose rate constant, radial dose function, and anisotropy function) of this source were experimentally and theoretically determined, following the AAPM Task Group 43 recommendations. Derivation of the dose rate constant was based on recent NIST WAFAC calibration performed in accordance with their 1999 standard. Measurements were performed in Solid Water phantom using LiF thermoluminescent dosimeters. The theoretical calculations were performed in both Solid Water and water using the PTRAN Monte Carlo code. The results indicated that a dose rate constant of the new source in water was 0.98 +/- 0.03 cGy h(-1) U(-1). The radial dose function of the new source was measured in Solid Water and calculated both in water and Solid Water at distances up to 10.0 cm. The anisotropy function, F(r, theta), of the new source was measured and calculated in Solid Water at distances of 2 cm, 3 cm, 5 cm, and 7 cm and also was calculated in water at distances ranging from 1 cm to 7 cm from the source. From the anisotropy function, the anisotropy factors and anisotropy constant were derived. The anisotropy constant of the ADVANTAGE 125I source in water was found to be 0.97 +/- 0.03. The dosimetric characteristics of this new source compared favorably with those from the Amersham Health Model 6711 source. Complete dosimetric parameters of the new source are presented in this paper.

Experimental determination of the TG-43 dosimetric characteristics of EchoSeed model 6733 I25I brachytherapy source

Recently an improved design of a 125I brachytherapy source has been introduced for interstitial seed implants, particularly for prostate seed implants. This design improves the in situ ultrasound visualization of the source compared to the conventional seed. In this project, the TG-43 recommended dosimetric characteristics of the new brachytherapy source have been experimentally determined in Solid Water phantom material. The measured dosimetric characteristics of the new source have been compared with data reported in the literature for other source designs. The measured dose rate constant, A, in Solid Water was multiplied by 1.05 to extract the dose rate constant in water. The dose rate constant of the new source in water was found to be 0.99 +/- 8% cGy h(-1) U(-1). The radial dose function was measured at distances between 0.5 and 10 cm using LiF TLDs in Solid Water phantom. The anisotropy function, F(r, theta), was measured at distances of 2, 3, 5, and 7 cm.

Determination of the dosimetric characteristics of InterSource125 iodine brachytherapy source

The TG-43 recommended dosimetric characteristics of a new 125I brachytherapy source have been experimentally and theoretically determined. The measurements were performed in Solid Water using LiF TLDs. The calculations were performed using Monte Carlo simulations in Solid Water and water. The measured data were compared with calculated values as well as the reported data in literature for other source designs. The dose rate constant this source in water was 1.01 +/- 3% cGy h(-1) U(-1) and the anisotropy constant was 0.956.

Dosimetric characteristics of the bests double-wall 103Pd brachytherapy source

103Pd and 125I brachytherapy sources are being used for interstitial implants in tumor sites such as the prostate. Recently, a double-wall 103Pd source has been introduced, which has a design different from that of sources presently on the market. Dosimetric characteristics (dose rate constant, radial dose function, and anisotropy function) of this source were experimentally and theoretically determined following the AAPM Task Group 43 recommendations and were related to the October 10, 2000 revision of the NIST 1999 SK Standard for 103Pd. Measurements were performed in a Solid Water phantom using LiF thermoluminescent dosimeters. For these measurements, slabs of Solid Water phantom material were machined to accommodate the source and LiF TLD chips of dimensions (3.1 x 3.1 x 0.8 mm3) and (1.0 x 1.0 x 1.0 mm3). The TLD chips were surrounded by at least 10 cm of Solid Water phantom material to provide full scattering conditions. The Monte Carlo simulations were performed in Solid Water and liquid water using the PTRAN code. The results of this investigation show an excellent agreement (within 5%) between the measured (0.67+/-8% cGy h(-1) U(-1)) and calculated (to be 0.65+/-3% cGy h(-1) U(-1)) dose rate constant in Solid Water. The Monte Carlo calculated dose rate constant of the Best 103Pd in water was found to be 0.67+/-0.02 cGy h(-1) U(-1). The radial dose function, g(r), of the new 103Pd source was measured at distances ranging from 0.5 and 7 cm using LiF TLD in Solid Water phantom material. Moreover, the radial dose function of the new source was calculated in liquid water and Solid Water at distances ranging from 0.1 to 7 cm using the PTRAN Monte Carlo Code. The anisotropy function, F(r, theta), of the new 103Pd source was also measured in Solid Water and calculated in both Solid Water and water phantom material. From the anisotropy functions, the anisotropy factors, and anisotropy constant were calculated for each medium. The results indicated that the measured anisotropy constant of the Best 103Pd source in Solid Water was 0.89+/-5%. Complete dosimetric data are described in this manuscript.

Experimental determination of dosimetric characteristics of Best 125I brachytherapy source

125I brachytherapy sources are being used for interstitial implants in tumor sites such as the prostate. Recently, the Best 125I source became commercially available for interstitial brachytherapy treatment. Dosimetric characteristics (dose rate constant, radial dose function, and anisotropy function) of this source were experimentally determined, following the AAPM Task Group 43 recommendations, and were related to the NIST 1999 calibration assigned to this source. Measurements were performed in Solid Water phantom using LiF thermoluminescent dosimeters. The results indicated a dose rate constant, lambda, of 1.01 +/- 0.08 cGy h(-1) U(-1) for the new source. The radial dose function, g(r), of the new source was measured at distances ranging from 0.5 to 10.0 cm. The anisotropy function, F(r, theta), of the new source was measured at distances of 2, 5, and 7 cm from the source center. These data compare favorably with those from the Nycomed/Amersham Models 6711 and 6702 sources. The anisotropy constant, phi(an), of the Best 125I source was found to be 0.982. Complete dosimetric parameters of the new source are presented in this paper.

Dosimetric characteristics of the Pharma Seed model BT-125-I source

125I brachytherapy sources are being used with increasing frequency for interstitial implants in tumor sites, especially the prostate. Recently, a new 125I source design has become commercially available for clinical applications. Dosimetric characteristics (i.e., dose rate constant, radial dose function, and anisotropy function) of this source were experimentally and theoretically determined following the AAPM Task Group 43 (TG-43) recommendations and were related to the 1999 NIST calibration assigned to this source [S(k), 99std]. Measurements were performed in a Solid Water phantom using LiF thermoluminescent dosimeters. The measured data were used to validate the Monte Carlo simulations that were performed in Solid Water using the PTRAN code. The Monte Carlo calculations were then performed in liquid water to obtain the dosimetric information for clinical applications in accordance with TG-43 recommendations. The results indicated that the dose rate constant, lambda, of the Pharma Seed model BT-125-I 125I source was 0.90 +/- 0.06 cGy h(-1) U(-1) using thermoluminescent dosimeter (TLD) measurements and 0.92 +/- 0.03 cGy h(-1) U(-1) using Monte Carlo simulations in Solid Water. The calculated value in liquid water was found to be 0.95 +/- 0.03 cGy h(-1) U(-1). The radial dose function, g(r), of the new 125I source was measured at distances ranging from 0.5 to 10 cm using LiF TLD in Solid Water phantom material. The Monte Carlo simulations were performed for distances ranging from 0.1 to 10 cm from the source center in Solid Water and liquid water. The anisotropy function, F(r, theta), was measured at distances of 2, 5, and 7 cm from the source center and calculated at distances of 0.5, 1, 2, 3, 5, and 7 cm from the source center. The anisotropy constant, phi(an), of the Pharma Seed source in water was found to be 0.975. Complete dosimetric data are described in this manuscript. Per TG-43, the values reported in water should be used for clinical treatment planning systems.

Dosimetric characteristics of the InterSource103 palladium brachytherapy source

103Pd brachytherapy sources are being used for interstitial implants in tumor sites such as the prostate. Recently, the InterSource103 palladium source has been introduced, which has a design different from that of other sources presently on the market. Dosimetric characteristics (i.e., dose rate constant, radial dose function, and anisotropy function) of this source were experimentally and theoretically determined following the AAPM Task Group 43 (TG-43) recommendations and were related to the 1999 NIST calibration assigned to this source [Sk, 99std]. Measurements were performed in a solid water phantom using LiF thermoluminescent dosimeters. The measured data was compared with Monte Carlo simulations performed in solid water using the PTRAN code. The calculations were then performed in liquid water to obtain the dosimetric information for clinical applications as per TG-43 recommendation. The results indicated that the dose rate constant, lambda, of the InterSource103 palladium source was 0.664+/-5% cGy/h/U using TLD measurements and 0.660+/-3% cGy/h/U using Monte Carlo simulations in solid water. The calculated value in liquid water was found to be 0.696 +/- 3 % cGy/h/U. The radial dose function, g(r), of the new 103Pd source was measured at distances ranging from 0.5 to 10 cm using LiF TLD in solid water phantom material. The Monte Carlo simulations were performed at distances ranging from 0.1 to 10 cm from the source center in solid water and liquid water. The anisotropy function, F(r, theta), was measured at distances of 2, 3, 5, and 7 cm from the source center and calculated at distances of 0.5, 1, 2, 3, 5, and 7 cm from the source center. Complete dosimetric data are described in this paper. Per TG-43, the values reported in water should be used for clinical treatment planning systems.

Palladium-103 brachytherapy for prostate carcinoma

PURPOSE

A report of biochemical outcomes for patients treated with palladium-103 (Pd-103) brachytherapy over a fixed time interval.

METHODS AND MATERIALS

Two hundred thirty patients with clinical stage T1-T2 prostate cancer were treated with Pd-103 brachytherapy and followed with prostate-specific antigen (PSA) determinations. Kaplan-Meier estimates of biochemical failure on the basis of two consecutive elevations of PSA were utilized. Multivariate risk groups were constructed. Aggregate PSA response by time interval was assessed.

RESULTS

The overall biochemical control rate achieved at 9 years was 83.5%. Failures were local 3.0%; distant 6.1%; PSA progression only 4.3%. Significant risk factors contributing to failure were serum PSA greater than 10 ng/ml and Gleason sum of 7 or greater. Five-year biochemical control for those exhibiting neither risk factor was 94%; one risk factor, 82%; both risk factors, 65%. When all 1354 PSA determinations obtained for this cohort were considered, the patients with a proportion of PSAs < or = 0.5 ng/ml continued to increase until at least 48 months post-therapy. These data conformed to a median PSA half-life of 96.2 days.

CONCLUSIONS

Prostate brachytherapy with Pd-103 achieves a high rate of biochemical and clinical control in patients with clinically organ-confined disease. PSA response following brachytherapy with low-dose-rate isotopes is protracted.

Results of hypofractionated stereotactic re-irradiation on 13 locally recurrent nasopharyngeal carcinomas

Thirteen patients with locally recurrent, previously-irradiated nasopharyngeal carcinoma were treated with linac-based hypofractionated stereotactic radiotherapy (24 Gy in two or four fractions). One- and 3-year overall survival were 54 and 31%. Three patients were free of disease at 30, 34 and 65 months. No severe acute or late complications were seen.

Permanent 125iodine implants for recurrent malignant gliomas

PURPOSE

To determine the efficacy and toxicity of permanent 125iodine implants for recurrent malignant gliomas.

METHODS AND MATERIALS

Between January 1989 and January:, 59 patients with histologically confirmed recurrent malignant gliomas (22 nonglioblastoma malignant gliomas, 37 glioblastoma multiforme at the time of implant) received a permanent 125iodine implant. Patients ranged in age from 13-74 years. The median ages for the overall group, nonglioblastoma (nonGBM), and glioblastoma (GBM) groups was 47 years, 39 years, and 53 years, respectively.

RESULTS

With a median follow-up of 40 months, the median survival for the 59 total patients is 1.34 years; nonGBM 2.04 years, GBM 0.9 years. Factors predictive for poor prognosis were GBM histology, age 60 years or more, target volume 17 cc or more, and/or tumor location within the corpus callosum or thalamus. Reoperations have been performed in 24 (40%) patients; 15 (25%) for tumor progression; 3 (5%) for radiation necrosis; 2 (3%) for skull necrosis/infection, and 4 (7%) for other reasons (Ommaya reservoir insertion, catheter removal, hematoma evacuation).

CONCLUSION

Permanent 125iodine implants in selected patients with recurrent malignant gliomas are associated with reasonable long-term survival and a low risk of complications. Given the low incidence of radiation necrosis, future plans are to increase dose rate and/or total dose delivered with the permanent implant.

Ten-year disease free survival after transperineal sonography-guided iodine-125 brachytherapy with or without 45-gray external beam irradiation in the treatment of patients with clinically localized, low to high Gleason grade prostate carcinoma

BACKGROUND

The authors report observed 10-year brachytherapy results in the treatment of 152 consecutive patients with clinically organ-confined prostate carcinoma.

METHODS

One hundred and fifty-two consecutive patients with T1-T3, low to high Gleason grade, prostate carcinoma were treated between January 1987 and June 1988 at Northwest Hospital in Seattle, Washington. Their median age was 70 years (range, 53-92 years). Of these 152 patients, 98 (64%) received an iodine-125 implant alone (Group 1), and the remaining 54 patients (36%), who were judged to have a higher risk of extraprostatic extension, also were treated with 45 gray (Gy) of external beam irradiation to the pelvis (Group 2). No patient underwent lymph node sampling, and none received androgen ablation therapy. Multivariate regression and the Mann-Whitney rank sum test were used for statistical analysis. Preoperative patient data with associated success or failure outcomes at 10 years after treatment were used for training and validating a back-propagation neural network prediction program.

RESULTS

The average preoperative prostate specific antigen (PSA) value, clinical stage, and Gleason grade were 11.0 ng/mL, T2, and 5, respectively. The median posttreatment follow-up was 119 months (range, 3-134 months). Overall survival 10 years after treatment was 65%. At last follow-up only 3 of the 152 patients (2%) had died of prostate carcinoma. Ninety-seven patients (64%) remained clinically and biochemically free of disease at 10 years of follow-up and had an average PSA value of 0.18 ng/mL (range, 0.01-0.5 ng/mL). In these patients a period of 42 months was required to reach the average PSA (0.5 ng/mL). The median to last PSA follow-up was 95 months (range, 3-134 months). Postoperative needle biopsies were negative in 56% of patients, positive in 15% of patients, and not available in 29% of patients. Only 6% of patients developed bone metastasis. At 10 years there was no statistically significant difference in treatment outcome between patients who received iodine-125 alone, and those who received iodine-125 with 45-Gy external beam irradiation (P = 0.08). Nevertheless, in these two groups preoperative PSA, stage, and Gleason grade were significantly different (P < 0.01). In the artificial neural network analysis, pretreatment serum PSA was the most accurate predictor of disease-free survival.

CONCLUSIONS

Percutaneous prostate brachytherapy is a valid and efficient option for treating patients with clinically organ-confined, low to high Gleason grade, prostate carcinoma. Observed 10-year follow-up documents serum PSA levels superior to those reported in several published external beam irradiation series, and comparable to those published in a number of published radical prostatectomy series.

Modern brachytherapy: current state and future prospects

This article reviews the current trends and future developments in brachytherapy. Established techniques including interstitial and high-dose rate brachytherapy are discussed with particular reference to lung, oesophageal, cervical and endometrial cancer. Intra-operative high-dose rate brachytherapy and other new techniques are also mentioned.

Pulmonary embolization of permanently implanted radioactive palladium-103 seeds for carcinoma of the prostate

PURPOSE

It has been reported that permanently implanted iodine-125 seeds can embolize to the lungs. There is little data on the embolization of palladium-103 seeds. The purpose of this study is to collect and evaluate data on the embolization of Pd-103 seeds.

METHODS AND MATERIALS

The records of 112 patients implanted with Pd-103 for carcinoma of the prostate were reviewed to systemically study the incidence and dynamics of pulmonary embolism of Pd-103 seeds. Five patients had no postoperative chest radiograph and were thus excluded, leaving 107 patients for review.

RESULTS

Chest radiographs of 19 of the 107 patients showed embolized seeds in the lungs (18%). Two patients had three seeds each, nine patients had two seeds each; and in the remaining eight patients, a single seed migrated to the lungs. The seeds migrated mainly (84%) to the lower lobes. None of the eight patients who had their first postoperative chest radiograph on the day of the implant showed any embolized seeds. The embolized seed appeared only on subsequent chest radiographs taken 27 to 40 days later. Ten of the other 11 patients who had their first radiograph 1 to 97 days after brachytherapy had embolized seeds on their first chest radiograph. In the other patient, the embolized seed appeared only on a subsequent chest radiograph taken after 127 days. There were no clinical pulmonary or cardiac effects evident on routine follow-up of these patients with pulmonary embolized seeds.

CONCLUSION

Embolization of Pd-103 seeds to the lungs after implantation for carcinoma of the prostate is an unusual event. In this study only 0.3% of the seeds implanted migrated to the lungs. Although it was previously thought that pulmonary seed migration mainly occurred on the day of brachytherapy, our experience shows that seeds usually migrated to the lungs after the day of the implant. There were no clinical pulmonary or cardiac effects attributable to embolized seeds in the lungs on routine follow-up.

Should brachytherapy be considered a therapeutic option in localized prostate cancer?

Contemporary prostate brachytherapy incorporates advances in computer analysis, imaging technology, and delivery apparatus, allowing exacting and reproducible results compared with historical approaches. The advances permit brachytherapy to be performed on a cost-effective, outpatient basis with low morbidity in the appropriately selected patient. Although unsettled questions remain regarding dosimetric issues, long-term outcomes, and morbidity, the weight of evidence to date appears to support the use of brachytherapy in selected patients. Brachytherapy may be considered a therapeutic option: as monotherapy for early-stage disease and also a boost following moderate doses of external beam irradiation for locally advanced disease.

Palladium-103: a new radioactive source in the treatment of unresectable carcinoma of the pancreas: a phase I-II study

Palladium-103 (Pd-103) is introduced in brachytherapy procedures because of its favorable physical properties, including its low energy, rapid dose fall-off, short half-life, and total cumulative dose delivery at a higher dose rate than iodine-125 (I-125) isotope. Intraoperative brachytherapy using I-125 pellets was reported to provide significant palliation and meaningful prolongation of life in highly selected patients with unresectable carcinoma of the pancreas. After considering some of the advantages of Pd-103 over I-125, we designed a phase I-II clinical trial to assess the feasibility of intraoperative Pd-103 in unresectable carcinoma of the pancreas to study the related morbidity when combined with chemotherapy and external beam radiation, and to evaluate the impact on palliation and local control rates. Between December 1989 and December 1993, 15 patients with biopsy-proven unresectable adenocarcinoma of the pancreas were treated with interstitial Pd-103 implants during laparotomy. In 13 patients the lesion was located in the head of the pancreas, in one patient in the uncinate process, and in one patient in the body of the pancreas. The stage distribution was as follows: T1 = 2; T2 = 6, and T3 = 7. In addition, all patients underwent biliary and gastric bypass. The mean number of Pd-103 pellets was 45; the mean total activity to obtain a matched peripheral dose (MPD) of 11,000 cGy was 68.9 mCi. The mean tumor volume encompassing the MPD was 16.5 cc. All patients received postoperative external beam radiation (4,500 cGy over 4 1/2 weeks) and chemotherapy (5-fluorouracil and mitomycin C). This combined treatment, consisting of intraoperative brachytherapy using Pd-103 and postoperative external beam radiation with chemotherapy, was well tolerated in all patients. These were no treatment-related mortalities, and no serious complications, such as bleeding or fistula formation. Pain relief was obtained within 3-6 weeks in 10 out of 12 patients presenting with pain. Survival ranged from 6 to 24 months (median 10 months). The study suggests that Pd-103 can be considered an alternative to I-125 for interstitial brachytherapy for unresectable carcinoma of the pancreas. Symptom relief appeared to occur faster and complications are significantly less. However, this study did not show any improvement in the median survival rate over I-125 due to the advanced stage cancer in the majority of patients in the study.

Transperineal palladium 103 prostate brachytherapy: analysis of morbidity and seed migration

OBJECTIVES

To evaluate the early morbidity of palladium 103 (103Pd) prostate brachytherapy.

METHODS

Thirty-two patients with Stage A or B prostate carcinoma were implanted transperineally with 103Pd using transrectal ultrasound and fluoroscopy between May 1990 and December 1992. Patients were subsequently followed to evaluate for morbidity and possibility of migration of the implanted seeds into the lungs.

RESULTS

The median follow-up time was 20 months (range, 2 to 45 months). The major acute toxicity of the procedure, dysuria, was seen in 88% of the patients. Although this was generally grade 1 or 2 and transient, grade 3 or 4 toxicity occurred in 18% of patients. Mild rectal symptoms (transient diarrhea, rectal bleeding) occurred in 19% of patients. Sexual functions could not be evaluated. Seven of the 3213 total seeds implanted (0.2%) were found to have migrated to the lung in 6 of 30 (20%) patients having a postoperative chest radiograph. This did not cause any clinical problems.

CONCLUSIONS

103Pd prostate brachytherapy is generally associated with only mild or moderate urinary and rectal symptoms, and the incidence of severe complications is low. Further follow-up is required to evaluate the efficacy.