Radioactive Implantation Research Articles

Monte Carlo calculated TG‐60 dosimetry parameters for the emitter brachytherapy source

The formalism recommended by Task Group 60 (TG-60) of the American Association of Physicists in Medicine (AAPM) is applicable for beta sources. Radioactive biocompatible and biodegradable 153Sm glass seed without encapsulation is a beta- emitter radionuclide with a short half-life and delivers a high dose rate to the tumor in the millimeter range. This study presents the results of Monte Carlo calculations of the dosimetric parameters for the 153Sm brachytherapy source. Version 5 of the (MCNP) Monte Carlo radiation transport code was used to calculate two-dimensional dose distributions around the source. The dosimetric parameters of AAPM TG-60 recommendations including the reference dose rate, the radial dose function, the anisotropy function, and the one-dimensional anisotropy function were obtained. The dose rate value at the reference point was estimated to be 9.21 +/- 0.6 cGy h(-1) microCi(-1). Due to the low energy beta emitted from 153Sm sources, the dose fall-off profile is sharper than the other beta emitter sources. The calculated dosimetric parameters in this study are compared to several beta and photon emitting seeds. The results show the advantage of the 153Sm source in comparison with the other sources because of the rapid dose fall-off of beta ray and high dose rate at the short distances of the seed. The results would be helpful in the development of the radioactive implants using 153Sm seeds for the brachytherapy treatment.

Radiation Protection of Persons Living Close to Patients with Radioactive Implants

Permanent interstitial brachytherapy is--in certain cases--a very successful therapeutic option, but application of radioactive implants always results in only gradually diminishing radiation exposure of persons in the patient's immediate surroundings. Using patients with clinically localized prostate cancer treated with iodine-125 ((125)I) or palladium-103 ((103)Pd) as an example, it is shown how a patient, if necessary or wished by him, can, by wearing commercially available X-ray protection shorts, reduce radiation exposure of family members in such a way that at a distance r from the patient a given dose per year is not exceeded. The computational procedures necessary for the determination of the individual periods of wearing X-ray protection clothing are provided in the form of formulae and graphics. All considerations and calculations can also be applied to other radiotherapeutic interventions involving the use of (125)I, (103)Pd or other gamma-sources. If necessary, a patient with permanent radioactive implants can reduce radiation exposure of family members by wearing special X-ray protection clothing for a limited period of time. This kind of radiation protection is very efficient and considerably simpler to accomplish than a reduction of exposure time or an increase of the distance between the patient and family members.

Long Term Results of a Phase II Trial of Ultrasound-guided Radioactive Implantation of the Prostate for Definitive Management of Localized Adenocarcinoma of the Prostate (RTOG 98–05)

Long Term Results of a Phase II Trial of Ultrasound-guided Radioactive Implantation of the Prostate for Definitive Management of Localized Adenocarcinoma of the Prostate (RTOG 98–05)

Application of iodine-125 interstitial implantation in cancerous pain

Pain is one of usual symptons of midlate cancer patients, radioactive particle interstitial implantation can not only control tumor advancement ,but also alleviate pain in different degree by inactivating part nerves or relieving compression. It has showed significant effect in system tumor-gastric cancer, colon cancer and head and neck cancer without severe complication, offering a new method of curing cancerous pain. Key words: Radiation ; Braehytherapy ; Neoplasms ; Pain

Program Marks New Direction in Schizophrenia Treatment

Program Marks New Direction in Schizophrenia Treatment

Study of the Sm-153 seeds degradation and evaluation of the absorbed dose in rabbit's liver implants

Bioceramics are attractive for radiation therapy. Implants in animals made of bioglasses of Si–Ca–Sm-153 will be addressed. Herein, the biocompatibility and biodegradability of Sm ceramic seeds produced by the sol–gel process are investigated, as well as, it will analyze the absorbed doses produced by the beta and gamma particles generated by Sm-153 decay, in the rabbit's liver. A set of Sm seeds was implanted in the liver of a rabbit. The high ecogenicity of the seed in the liver turns it easily identifiable in ultrasonography. The capacity of absorption of the seeds was investigated in the organ monitored by ultrasonography. Seven months later, after radiological exploration, the seeds showed to be absorbed in the liver. The biodegradability was also verified by X-ray, attesting what had already been observed in the ultrasonography. A computational model was also elaborated to predict absorbed doses in multiple seed's arrangements. CT images of the thoracic–abdominal area of the rabbit were digitalized and used to produce the voxel computational model. Dosimetry was accomplished through the MCNP5 code. Spatial dose rate distribution in the liver is presented. The results will help in future the project of the radioactive implants using hot-ceramic-seeds.

Prevention of tumor recurrence and distant metastasis formation in a breast cancer mouse model by biodegradable implant of 131I-norcholesterol

Brachytherapy has many potential roles in cancer therapy. However, major constraints are associated with placement and removal procedures of the brachytherapy machinery. An attractive approach would be the use of a biodegradable implant loaded with a radioisotope, thus enabling targeted radiotherapy, while reducing the need for surgical procedures for the removal of brachytherapy hardware . In this study, crosslinked chitosan (Ct) hydrogels were prepared and loaded with 131I-norcholesterol ( 131I–NC). The radioactive hydrogels ( 131I–NC–Ct) were implanted adjacent to 4T1 cell-induced tumors in two different xenograft mice models either as primary therapy or surgical adjuvant therapy of breast cancer. Non-treated mice and mice implanted with naive (non-radioactive) hydrogels served as control groups. In the primary therapy model, the progression rate of the tumor was delayed by two weeks compared with the non-treated and the naive-implant control animals, resulting in a one-week extension in the survival of the treated animals. In the adjuvant therapy model, for the treatment of minimal residual disease, 131I–NC–Ct implants were able to prevent 69% of tumor recurrence, and to prevent metastatic spread resulting in long-term survival, compared with 0% long-term survival of the non-treated and the naive control groups. Imaging of the hydrogel's in vivo elimination revealed a first order process with a half-life of 14 days. The degradation was caused by oxidation of the Ct as was assessed by in vitro H&E stain. Biodegradable radioactive implants are suggested as a novel platform for the delivery of brachytherapy. This radiotherapy regimen may prevent locoregional recurrence and metastatic spread after tumor resection .

Operative matching points for patients with maxillofacial malignant tumor when cured by radioactive particle implantation and the counter prevention measures

目的 探讨放射性粒子植入组织间治疗颌面部恶性肿瘤的护理配合要点.方法 回顾分析50例颌面部恶性肿瘤患者放射性粒子组织间植入治疗的护理配合要点.结果 由于对接受本项治疗的患者进行了合理的护理,本组患者均顺利完成放射性粒子治疗,无伤口感染及不愈合;通过耐心的交流及宣教,使患者及家属对本项治疗产生的焦虑得以解决.结论 完善的术前准备,必要的放射防护知识,以及了解患者对于本项治疗的不适心理并进行宣教是护理配合的重点。

Biodegradable radioactive implants for glaucoma filtering surgery produced by ion implantation

A biodegradable, β-emitting implant has been developed and successfully tested which prevents fresh intraocular pressure increase after glaucoma filtering surgery. Ion implantation has been used to load the polymeric implants with the β-emitter 32P. The influence of ion implantation and gamma sterilisation on degradation and 32P-fixation behavior has been studied by ion beam and chemical analysis. Irradiation effects due to the applied ion fluence (1015 ions/cm2) and gamma dose (25kGy) are found to be tolerable.

Results of a phase II trial of transrectal ultrasound-guided permanent radioactive implantation of the prostate for definitive management of localized adenocarcinoma of the prostate (Radiation Therapy Oncology Group 98-05)

To evaluate the effectiveness of transrectal ultrasound-guided permanent radioactive (125)I implantation of the prostate for organ-confined adenocarcinoma of the prostate compared with historical data of prostatectomy and external beam radiotherapy within a cooperative group setting. Patients accrued to this study had histologically confirmed, locally confined, adenocarcinoma of the prostate with clinical Stage T1b, T1c, or T2a, no nodal or metastatic disease, prostate-specific antigen level of < or =10 ng/mL, and Gleason score of < or =6. All patients underwent transrectal ultrasound-guided radioactive (125)I permanent seed implantation into the prostate. The prescribed dose was 145 Gy to the prostate planning target volume. A total of 27 institutions accrued a total of 101 patients to this protocol, with no institution accruing >8 patients. Six patients were ineligible, leaving 95 properly entered as eligible in the study. The median follow-up was 5.3 years (range, 0.4-6.5 years). At 5 years, 5 patients had local failure, 1 had evidence of distant failure, and 6 (6%) had biochemical failure. The overall survival rate at 5 years was 96.7%. At last follow-up, no patient had died of prostate cancer or related toxicities. Eight patients had a maximal acute toxicity level of 3, and no patient had Grade 4 or 5 acute toxicity. During follow-up, 2 patients had maximal Grade 3 toxicity, both related to bladder issues, and no patient experienced Grade 4 or 5 toxicity. The results of this clinical protocol (a multi-institutional trial of brachytherapy for localized adenocarcinoma of the prostate) have demonstrated that this type of trial can be successfully completed through the Radiation Therapy Oncology Group. Biochemical disease-free survival was comparable with other brachytherapy published series and with the results after surgery and external beam radiotherapy.

Cancer incidence after localized therapy for prostate cancer

Second cancers may occur in patients who have undergone radiation therapy. The risk for these adverse events after therapy is uncertain. In this study, the authors examined the size and significance of the observed association between occurrences of secondary cancers 5 years after radiotherapy in a large population of men with incident prostate cancer. Men with incident prostate cancer were identified from the Surveillance, Epidemiology, and End Results (SEER) registry and were distinguished by the type of treatment received, tumor stage, tumor grade, and age at diagnosis. SEER data also were used to identify occurrences of secondary cancer beginning 5 years after the date patients were diagnosed with prostate cancer. Multivariate logistic regression analysis was used to estimate the adjusted odds of the subsequent occurrence of other cancers associated with types of radiation therapy received and was adjusted for the type of surgery, tumor grade, stage, and patient age. Compared with men who received no prostate cancer-directed radiation, men who received external beam radiation therapy (EBRT) as their only form of radiation therapy had statistically significant increased odds of developing secondary cancers at several sites potentially related to radiation therapy, including the bladder (odds ratio [OR], 1.63; 95% confidence interval [95% CI], 1.44-1.84) and rectum (OR, 1.60; 95% CI, 1.29-1.99). Men who received EBRT also had statistically significant higher odds of developing secondary cancers at sites in the upper body and other areas not potentially related to radiation therapy, including the cecum (OR, 1.63; 95% CI, 1.10-1.70), transverse colon (OR, 1.85; 95% CI, 1.30-2.63), brain (OR, 1.83; 95% CI, 1.22-2.75), stomach (OR, 1.38; 95% CI, 1.09-1.75), melanoma (OR, 1.29; 95% CI, 1.09-1.53), and lung and bronchus (OR, 1.25; 95% CI, 1.13-1.37) compared with the odds among men who received no radiation therapy. Men who received radiation therapy in the form of radioactive implants or isotopes, either in isolation or combined with beam radiation, did not have significantly different odds of secondary cancer occurring at any of the 20 most common sites. Patients who received with EBRT had significantly higher odds of developing second cancers both overall and in the areas that were exposed to radiation. It is noteworthy that, to the authors' knowledge, this report shows for the first time that, despite the higher doses of radiation delivered, patients who received radioactive implants had the lowest odds of developing second cancers.

Quality assurance methods for the first Radiation Therapy Oncology Group permanent prostate implant protocol

Purpose To report the quality assurance methodology used by the Radiation Therapy Oncology Group in the first cooperative group, multi-institution Phase II trial of transrectal ultrasound guided permanent radioactive implantation of the prostate for definitive treatment of localized adenocarcinoma of the prostate. Methods and materials Participating institutions were credentialed to participate in this protocol, Radiation Therapy Oncology Group 98-05. International Commission on Radiation Units and Measurements (ICRU) Report 58 was used as the basis for definition of terms. The AAPM's dosimetric prerequisites for low energy interstitial brachytherapy sources were adopted. A nondigital approach to central review was used. The implant dosimetry was recalculated based upon centrally reviewed target volumes by both a radiation oncologist and a diagnostic radiologist. Results There are differences in the definition of the postimplant prostate between the participating institution, the central review radiation oncologist, and the central review diagnostic radiologist. Thus, there are differences in dose/volume parameters. Six of the 95 patients reviewed did not meet the per protocol criteria based upon information supplied by the participating institution. This increased to 18 cases when using the postimplant target volume defined by the central oncologist and to 23 cases when defined by the radiologist. Conclusions This work indicated that there is a need for a central review process of dose–volume analysis within the cooperative group setting. It is indicated that a digital approach to centralized review, which has now been developed, would result in a higher quality and easier review.

Long-term results of interstitial brachytherapy (LDR-Brachytherapy) in the treatment of patients with prostate cancer

Permanent interstitial brachytherapy represents the most conformal form of radiation therapy of the prostate and the number of patients with prostate cancers treated with permanent radioactive implants is increasing world wide. In the meanwhile long-term data on tumor control and treatment morbidity become available. Biochemical and clinical tumor control appears to be as effective as after radical prostatectomy or external beam radiation therapy in early prostate cancer. The risk of postreatment urinary incontinence and bowel dysfunction is low and erectile function can be preserved in the majority of patients. However, prostate brachytherapy requires a careful selection of patients as pretreatment factors predict for long-term outcome. The need for combined modality approaches in intermediate and high-risk patients remains controversely discussed. The continous refinement of intraoperative planning techniques and the elucidation of the etiology of urinary, sexual, and bowel dysfunction should result in further improvements in biochemical outcomes and decreased morbidity. Improved and standardized postimplantation evaluation will make outcome data more reliable and comparable.

Interstitial Brachytherapy (LDR-Brachytherapy) in the Treatment of Patients with Prostate Cancer

Objectives As the number of patients with prostate cancer treated with permanent radioactive implants is increasing world wide, long-term data on tumor control and treatment morbidity become available. Materials Biochemical and clinical tumor control appears to be as effective as after radical prostatectomy or external beam radiation therapy in early prostate cancer. Results The risk of posttreatment urinary incontinence and bowel dysfunction is low and erectile function can be preserved in the majority of patients. However, prostate brachytherapy requires a careful selection of patients as pretreatment factors predict for long-term outcome. The need for combined modality approaches in intermediate and high risk patients remains controversely discussed. The continuous refinement of intraoperative planning techniques and the elucidation of the etiology of urinary, sexual and bowel dysfunction should result in further improvements in biochemical outcomes and decreased morbidity. Conclusions Improved and standardized postimplantation evaluation will make outcome data more reliable and comparable.

Salvage treatment for inoperable neck nodes in head and neck cancer using combined iridium-192 brachytherapy and surgical reconstruction.

The results of debulking surgery and re-irradiation with radioactive implants (brachytherapy) are reported for 39 patients with inoperable metastatic neck nodes from primary head and neck cancers. For 13 patients conventional salvage by partial debulking surgery and brachytherapy proved effective, with 68 per cent control at 1 year, but six patients suffered severe radiation fibrosis, necrosis and contractures. Some 26 patients were treated by combined tumour debulking, skin resurfacing and brachytherapy implant. Initial tumour control and freedom from serious toxicity was achieved in 24 patients. Local control was achieved in 63 per cent of patients at 1 year, with a serious morbidity rate of 12 per cent.

Radio-active implantation of the pituitary.

Radio-active implantation of the pituitary.

HIGHLIGHTS FROM THE SOCIETY OF UROLOGIC ONCOLOGY, 5TH ANNUAL MEETING, DECEMBER 3–4, 2004, BETHESDA, MARYLAND, UNITED STATES OF AMERICA

The fifth annual meeting of the Society of Urologic Oncology was held December 3 and 4, 2004 in Bethesda, Maryland. The program provides a forum for the discussion of important issues in genitourinary malignancies among urologists, radiation oncologists and medical oncologists. Agenda topics included kidney cancer, bladder cancer and prostate cancer. Several sessions featured new developments in basic, translational and clinical research. Each session was reviewed for content following the meeting and the highlights were summarized. The Young Urologic Oncologists' Forum was again a successful component of the meeting but it is beyond the scope of this summary. Sessions on kidney cancer focused on molecular genetics and advances in molecular therapeutics. Radio frequency ablation of renal masses was also addressed. Topics discussed in bladder cancer included screening and surgical management. Dr. Donald Skinner received the Huggins Medal and he addressed the society on the management of invasive bladder cancer. Reviewed session topics in prostate cancer included neoadjuvant treatment paradigms, radiation treatment and adjuvant therapy in patients in whom primary treatment has failed. A state-of-the-art lecture addressed hereditary prostate cancer. The Society of Urologic Oncology meeting is unique in its multidisciplinary forum and focus on urological oncology. The meeting this year highlighted emerging trends, and the current state-of-the-art in kidney, bladder and prostate cancer. Additional focus was given to new molecular based diagnostic and therapeutic strategies for genitourinary malignancies.

Study of the Pd–Rh interdiffusion by three complementary analytical techniques: PIXE, RBS and ToF-SIMS

Pd diffusion in Rh has a great interest in the 103Pd* production intended to brachytherapy, a cancer treatment using radioactive implants. In order to study that diffusion, DC-magnetron sandwich layers of natural Pd and Rh were produced, annealed, and the Pd profiles were measured by ToF-SIMS. Nevertheless, because ToF-SIMS depth profiles suffer from a lack of quantification and depth calibration, the study was completed by RBS, PIXE. The combination of these techniques allowed us to convert the ToF-SIMS depth profiles from an intensity–time to a concentration–depth profile and thus to study the Pd diffusion in Rh.

Radiotherapy for primary thyroid cancer as a risk factor for second primary cancers

Although radiation is considered a risk factor for thyroid cancer, the potential relationship between radiation therapy and the risk of second primary cancer among patients with first primary thyroid cancer has not been evaluated. We identified 26,639 patients with first primary thyroid cancer in the Surveillance, Epidemiology, and End Results (SEER) database from 1973 to 2000. Information on radiation therapy as well as second primary cancers was recorded in SEER. The proportional hazards model was utilized to estimate adjusted risk ratios (RRs) and their 95% confidence intervals (CIs) to assess the potential association between radiation therapy for thyroid cancer and the risk of second primary cancers. With 270,674.33 person-years of follow-up, 1,896 (7.1%) of the 26,639 patients with first primary thyroid cancer developed second primary cancers. Among the second primaries, 35 occurred in the thyroid. No obvious association was observed between radiation therapy and the overall risk of second primary cancer after ten years of follow-up (RR=1.07, 95% CI=0.88–1.30). However, an increased risk was seen for several cancers, including upper digestive system cancers (RR=1.66, 95% CI=1.07–2.57) and myeloid malignancies (RR=3.26, 95% CI=1.39–7.67). Radiation therapy was associated with reduced second cancer risks for thyroid cancer (RR=0.18, 95% CI=0.04–0.76). Beam radiation might be important to the digestive system, radioactive implants might be associated with the male genital system, radioisotopes might have an effect on myeloid malignancies, and combined beam radiation with radioactive implants or radioisotopes might be related to the increased risk of respiratory system cancers. This study suggests that radiation therapy for patients with first primary thyroid cancer might be associated with an increased risk of developing a second primary cancer in the upper digestive system and second primary myeloid malignancies. Radiation therapy for adult patients with thyroid cancer might be associated with a reduced risk of second primary thyroid cancer.

Preface, Main Points, Executive Summary, Introduction

The use of permanent radioactive implants (125I or 103Pd seeds) to treat selected localised prostate cancer patients has been increasing rapidly all over the world for the last 15 years. It is estimated that more than 50,000 patients are treated this way every year in the world, and this number is anticipated to increase in the near future. Although no accidents or adverse effects involving medical staff and/or members of the patient's family have been reported to date, this brachytherapy technique raises a number of radiation safety issues that need specific recommendations from the ICRP. All data concerning the dose received by people approaching patients after implantation have been reviewed. Those doses have been either been measured directly or calculated. The available data show that, in the vast majority of cases, the dose to comforters and carers remains well below the recommended limit of 1 mSv/year. Only the (rare) case where the patient's partner is pregnant at the time of implantation may need specific precautions. Expulsion of sources through urine, semen, or the gastro-intestinal tract is rare. Specific recommendations should be given to patients to allow them to deal adequately with this event. Of note, due to the low activity of an isolated seed and its low photon energy, no incident/accident linked to seed loss has ever been recorded. When performed in the first few months after implantation, cremation of bodies (frequent in some countries) raises several issues related to: (1) the activity that remains in the patient's ashes; and (2) the airborne dose, potentially inhaled by crematorium staff or members of the public. Review of available data shows that cremation can be allowed if 12 months have elapsed since implantation with 125I (3 months for 103Pd). If the patient dies before this delay has elapsed, specific measures must be undertaken. Specific recommendations have to be given to the patient to warn his surgeon in case of subsequent pelvic or abdominal surgery. A 'wallet card' with all relevant information about the implant is useful. In most cases, brachytherapy does make the patient infertile. However, although the therapy-related modifications of the semen reduce fertility, patients must be aware of the possibility of fathering children after such a permanent implantation, with a limited risk of genetic effects for the child. Patients with permanent implants must be aware of the possibility of triggering certain types of security radiation monitors. The 'wallet card' including the main information about the implant (see above) may prove to be helpful in such a case. Considering the available experience after brachytherapy and external irradiation of prostate cancer, the risk of radio-induced secondary tumours appears to be extremely low. The demonstrated benefit of brachytherapy clearly outweighs, by far, the very limited (mainly theoretical)increase in the radiation-induced cancer risk.