Lessons Learned from Autopsying an Unidentified Body with Iodine-125 Seeds Implanted for Prostate Brachytherapy.

PubMed

Idota, Nozomi; Nakamura, Mami; Masui, Koji; Kakiuchi, Yasuhiro; Yamada, Kei; Ikegaya, Hiroshi

2017-03-01

We report here lessons learned from an autopsy case involving radioactive materials. We performed an autopsy of an unidentified mummified man with no available medical history whom from imaging findings we suspected had received radioactive seed implants for prostate brachytherapy. We returned the excised prostate and seeds to the body. A few days later, the body was identified by DNA matching and cremated. According to the man's medical record, he had undergone iodine-125 seeds implantation for prostate cancer 11 months earlier. We should have removed the radioactive seeds from the body to prevent radiation exposure to the bereaved family and/or environmental pollution due to cremation. Surprisingly, one seed was found in the stored prostate specimen. Forensic experts should be cognizant of the risk of both radiation exposure in the autopsy room and environmental pollution. We must remain abreast of the latest advances in medicine. © 2016 American Academy of Forensic Sciences.

Well-ionization chamber response relative to NIST air-kerma strength standard for prostate brachytherapy seeds.

PubMed

Mitch, M G; Zimmerman, B E; Lamperti, P J; Seltzer, S M; Coursey, B M

2000-10-01

The response of well-ionization chambers to the emissions of 103Pd and 125I radioactive seed sources used in prostate cancer brachytherapy has been measured. Calibration factors relating chamber response (current or dial setting) to measured air-kerma strength have been determined for seeds from nine manufacturers, each with different designs. Variations in well-ionization chamber response relative to measured air-kerma strength have been observed because of differences in the emitted energy spectrum due to both the radionuclide support material (125I seeds) and the mass ratio of 103Pd to 102Pd (103Pd seeds). Obtaining accurate results from quality assurance measurements using well-ionization chambers at a therapy clinic requires knowledge of such differences in chamber response as a function of seed design.

Health-Related Quality of Life up to Six Years After {sup 125}I Brachytherapy for Early-Stage Prostate Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roeloffzen, Ellen M.A., E-mail: E.M.A.Roeloffzen@UMCUtrecht.n; Lips, Irene M.; Gellekom, Marion P.R. van

2010-03-15

Purpose: Health-related quality of life (HRQOL) after prostate brachytherapy has been extensively described in published reports but hardly any long-term data are available. The aim of the present study was to prospectively assess long-term HRQOL 6 years after {sup 125}I prostate brachytherapy. Methods and Materials: A total of 127 patients treated with {sup 125}I brachytherapy for early-stage prostate cancer between December 2000 and June 2003 completed a HRQOL questionnaire at five time-points: before treatment and 1 month, 6 months, 1 year, and 6 years after treatment. The questionnaire included the RAND-36 generic health survey, the cancer-specific European Organization for Researchmore » and Treatment of Cancer core questionnaire (EORTCQLQ-C30), and the tumor-specific EORTC prostate cancer module (EORTC-PR25). A change in a score of >=10 points was considered clinically relevant. Results: Overall, the HRQOL at 6 years after {sup 125}I prostate brachytherapy did not significantly differ from baseline. Although a statistically significant deterioration in HRQOL at 6 years was seen for urinary symptoms, bowel symptoms, pain, physical functioning, and sexual activity (p <.01), most changes were not clinically relevant. A statistically significant improvement at 6 years was seen for mental health, emotional functioning, and insomnia (p <.01). The only clinically relevant changes were seen for emotional functioning and sexual activity. Conclusion: This is the first study presenting prospective HRQOL data up to 6 years after {sup 125}I prostate brachytherapy. HRQOL scores returned to approximately baseline values at 1 year and remained stable up to 6 years after treatment. {sup 125}I prostate brachytherapy did not adversely affect patients' long-term HRQOL.« less

A modern Monte Carlo investigation of the TG-43 dosimetry parameters for an {sup 125}I seed already having AAPM consensus data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aryal, Prakash; Molloy, Janelle A.; Rivard, Mark J., E-mail: mark.j.rivard@gmail.com

2014-02-15

Purpose: To investigate potential causes for differences in TG-43 brachytherapy dosimetry parameters in the existent literature for the model IAI-125A{sup 125}I seed and to propose new standard dosimetry parameters. Methods: The MCNP5 code was used for Monte Carlo (MC) simulations. Sensitivity of dose distributions, and subsequently TG-43 dosimetry parameters, was explored to reproduce historical methods upon which American Association of Physicists in Medicine (AAPM) consensus data are based. Twelve simulation conditions varying{sup 125}I coating thickness, coating mass density, photon interaction cross-section library, and photon emission spectrum were examined. Results: Varying{sup 125}I coating thickness, coating mass density, photon cross-section library, andmore » photon emission spectrum for the model IAI-125A seed changed the dose-rate constant by up to 0.9%, about 1%, about 3%, and 3%, respectively, in comparison to the proposed standard value of 0.922 cGy h{sup −1} U{sup −1}. The dose-rate constant values by Solberg et al. [“Dosimetric parameters of three new solid core {sup 125}I brachytherapy sources,” J. Appl. Clin. Med. Phys. 3, 119–134 (2002)], Meigooni et al. [“Experimental and theoretical determination of dosimetric characteristics of IsoAid ADVANTAGE™ {sup 125}I brachytherapy source,” Med. Phys. 29, 2152–2158 (2002)], and Taylor and Rogers [“An EGSnrc Monte Carlo-calculated database of TG-43 parameters,” Med. Phys. 35, 4228–4241 (2008)] for the model IAI-125A seed and Kennedy et al. [“Experimental and Monte Carlo determination of the TG-43 dosimetric parameters for the model 9011 THINSeed™ brachytherapy source,” Med. Phys. 37, 1681–1688 (2010)] for the model 6711 seed were +4.3% (0.962 cGy h{sup −1} U{sup −1}), +6.2% (0.98 cGy h{sup −1} U{sup −1}), +0.3% (0.925 cGy h{sup −1} U{sup −1}), and −0.2% (0.921 cGy h{sup −1} U{sup −1}), respectively, in comparison to the proposed

Ejaculatory function after permanent 125I prostate brachytherapy for localized prostate cancer.

PubMed

Huyghe, Eric; Delannes, Martine; Wagner, Fabien; Delaunay, Boris; Nohra, Joe; Thoulouzan, Matthieu; Shut-Yee, J Yeung; Plante, Pierre; Soulie, Michel; Thonneau, Patrick; Bachaud, Jean Marc

2009-05-01

Ejaculatory function is an underreported aspect of male sexuality in men treated for prostate cancer. We conducted the first detailed analysis of ejaculatory function in patients treated with permanent (125)I prostate brachytherapy for localized prostate cancer. Of 270 sexually active men with localized prostate cancer treated with permanent (125)I prostate brachytherapy, 241 (89%), with a mean age of 65 years (range, 43-80), responded to a mailed questionnaire derived from the Male Sexual Health Questionnaire regarding ejaculatory function. Five aspects of ejaculatory function were examined: frequency, volume, dry ejaculation, pleasure, and pain. Of the 241 sexually active men, 81.3% had conserved ejaculatory function after prostate brachytherapy; however, the number of patients with rare/absent ejaculatory function was double the pretreatment number (p < .0001). The latter finding was correlated with age (p < .001) and the preimplant International Index of Erectile Function score (p < .001). However, 84.9% of patients with maintained ejaculatory function after implantation reported a reduced volume of ejaculate compared with 26.9% before (p < .001), with dry ejaculation accounting for 18.7% of these cases. After treatment, 30.3% of the patients experienced painful ejaculation compared with 12.9% before (p = .0001), and this was associated with a greater number of implanted needles (p = .021) and the existence of painful ejaculation before implantation (p < .0001). After implantation, 10% of patients who continued to be sexually active experienced no orgasm compared with only 1% before treatment. in addition, more patients experienced late/difficult or weak orgasms (p = .001). Most men treated with brachytherapy have conserved ejaculatory function after prostate brachytherapy. However, most of these men experience a reduction in volume and a deterioration in orgasm.

An in vitro verification of strength estimation for moving an 125I source during implantation in brachytherapy.

PubMed

Tanaka, Kenichi; Kajimoto, Tsuyoshi; Hayashi, Takahiro; Asanuma, Osamu; Hori, Masakazu; Kamo, Ken-Ichi; Sumida, Iori; Takahashi, Yutaka; Tateoka, Kunihiko; Bengua, Gerard; Sakata, Koh-Ichi; Endo, Satoru

2018-04-11

This study aims to demonstrate the feasibility of a method for estimating the strength of a moving brachytherapy source during implantation in a patient. Experiments were performed under the same conditions as in the actual treatment, except for one point that the source was not implanted into a patient. The brachytherapy source selected for this study was 125I with an air kerma strength of 0.332 U (μGym2h-1), and the detector used was a plastic scintillator with dimensions of 10 cm × 5 cm × 5 cm. A calibration factor to convert the counting rate of the detector to the source strength was measured and then the accuracy of the proposed method was investigated for a manually driven source. The accuracy was found to be under 10% when the shielding effect of additional needles for implantation at other positions was corrected, and about 30% when the shielding was not corrected. Even without shielding correction, the proposed method can detect dead/dropped source, implantation of a source with the wrong strength, and a mistake in the number of the sources implanted. Furthermore, when the correction was applied, the achieved accuracy came close to within 7% required to find the Oncoseed 6711 (125I seed with unintended strength among the commercially supplied values of 0.392, 0.462 and 0.533 U).

Towards clinical application of RayStretch for heterogeneity corrections in LDR permanent 125I prostate brachytherapy.

PubMed

Hueso-González, Fernando; Ballester, Facundo; Perez-Calatayud, Jose; Siebert, Frank-André; Vijande, Javier

RayStretch is a simple algorithm proposed for heterogeneity corrections in low-dose-rate brachytherapy. It is built on top of TG-43 consensus data, and it has been validated with Monte Carlo (MC) simulations. In this study, we take a real clinical prostate implant with 71 125 I seeds as reference and we apply RayStretch to analyze its performance in worst-case scenarios. To do so, we design two cases where large calcifications are located in the prostate lobules. RayStretch resilience under various calcification density values is also explored. Comparisons against MC calculations are performed. Dose-volume histogram-related parameters like prostate D 90 , rectum D 2cc , or urethra D 10 obtained with RayStretch agree within a few percent with the detailed MC results for all cases considered. The robustness and compatibility of RayStretch with commercial treatment planning systems indicate its applicability in clinical practice for dosimetric corrections in prostate calcifications. Its use during intraoperative ultrasound planning is foreseen. Copyright © 2017 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

The use of new GAFCHROMIC EBT film for 125I seed dosimetry in Solid Water phantom.

PubMed

Chiu-Tsao, Sou-Tung; Medich, David; Munro, John

2008-08-01

Radiochromic film dosimetry has been extensively used for intravascular brachytherapy applications for near field within 1 cm from the sources. With the recent introduction of new model of radiochromic films, GAFCHROMIC EBT, with higher sensitivity than earlier models, it is promising to extend the distances out to 5 cm for low dose rate (LDR) source dosimetry. In this study, the use of new model GAFCHROMIC EBT film for 125I seed dosimetry in Solid Water was evaluated for radial distances from 0.06 cm out to 5 cm. A multiple film technique was employed for four 125I seeds (Implant Sciences model 3500) with NIST traceable air kerma strengths. Each experimental film was positioned in contact with a 125I seed in a Solid Water phantom. The products of the air kerma strength and exposure time ranged from 8 to 3158 U-h, with the initial air kerma strength of 6 U in a series of 25 experiments. A set of 25 calibration films each was sequentially exposed to one 125I seed at about 0.58 cm distance for doses from 0.1 to 33 Gy. A CCD camera based microdensitometer, with interchangeable green (520 nm) and red (665 nm) light boxes, was used to scan all the films with 0.2 mm pixel resolution. The dose to each 125I calibration film center was calculated using the air kerma strength of the seed (incorporating decay), exposure time, distance from seed center to film center, and TG43U1S1 recommended dosimetric parameters. Based on the established calibration curve, dose conversion from net optical density was achieved for each light source. The dose rate constant was determined as 0.991 cGy U(-1)h(-1) (+/-6.9%) and 1.014 cGy U(-1)h(-1) (+/-6.8%) from films scanned using green and red light sources, respectively. The difference between these two values was within the uncertainty of the measurement. Radial dose function and 2D anisotropy function were also determined. The results obtained using the two light sources corroborated each other. We found good agreement with the TG43U1S1

Ejaculatory Function After Permanent {sup 125}I Prostate Brachytherapy for Localized Prostate Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huyghe, Eric; Department of Urology and Andrology, Paul Sabatier University, CHU Paule de Viguier, Toulouse; Delannes, Martine

Purpose: Ejaculatory function is an underreported aspect of male sexuality in men treated for prostate cancer. We conducted the first detailed analysis of ejaculatory function in patients treated with permanent {sup 125}I prostate brachytherapy for localized prostate cancer. Patients and Methods: Of 270 sexually active men with localized prostate cancer treated with permanent {sup 125}I prostate brachytherapy, 241 (89%), with a mean age of 65 years (range, 43-80), responded to a mailed questionnaire derived from the Male Sexual Health Questionnaire regarding ejaculatory function. Five aspects of ejaculatory function were examined: frequency, volume, dry ejaculation, pleasure, and pain. Results: Of themore » 241 sexually active men, 81.3% had conserved ejaculatory function after prostate brachytherapy; however, the number of patients with rare/absent ejaculatory function was double the pretreatment number (p < .0001). The latter finding was correlated with age (p < .001) and the preimplant International Index of Erectile Function score (p < .001). However, 84.9% of patients with maintained ejaculatory function after implantation reported a reduced volume of ejaculate compared with 26.9% before (p < .001), with dry ejaculation accounting for 18.7% of these cases. After treatment, 30.3% of the patients experienced painful ejaculation compared with 12.9% before (p = .0001), and this was associated with a greater number of implanted needles (p = .021) and the existence of painful ejaculation before implantation (p < .0001). After implantation, 10% of patients who continued to be sexually active experienced no orgasm compared with only 1% before treatment. in addition, more patients experienced late/difficult or weak orgasms (p = .001). Conclusion: Most men treated with brachytherapy have conserved ejaculatory function after prostate brachytherapy. However, most of these men experience a reduction in volume and a deterioration in orgasm.« less

Monte Carlo Determination of Dosimetric Parameters of a New (125)I Brachytherapy Source According to AAPM TG-43 (U1) Protocol.

PubMed

Baghani, Hamid Reza; Lohrabian, Vahid; Aghamiri, Mahmoud Reza; Robatjazi, Mostafa

2016-03-01

(125)I is one of the important sources frequently used in brachytherapy. Up to now, several different commercial models of this source type have been introduced to the clinical radiation oncology applications. Recently, a new source model, IrSeed-125, has been added to this list. The aim of the present study is to determine the dosimetric parameters of this new source model based on the recommendations of TG-43 (U1) protocol using Monte Carlo simulation. The dosimetric characteristics of Ir-125 including dose rate constant, radial dose function, 2D anisotropy function and 1D anisotropy function were determined inside liquid water using MCNPX code and compared to those of other commercially available iodine sources. The dose rate constant of this new source was found to be 0.983+0.015 cGyh-1U-1 that was in good agreement with the TLD measured data (0.965 cGyh-1U-1). The 1D anisotropy function at 3, 5, and 7 cm radial distances were obtained as 0.954, 0.953 and 0.959, respectively. The results of this study showed that the dosimetric characteristics of this new brachytherapy source are comparable with those of other commercially available sources. Furthermore, the simulated parameters were in accordance with the previously measured ones. Therefore, the Monte Carlo calculated dosimetric parameters could be employed to obtain the dose distribution around this new brachytherapy source based on TG-43 (U1) protocol.

Monte Carlo dosimetry for {sup 103}Pd, {sup 125}I, and {sup 131}Cs ocular brachytherapy with various plaque models using an eye phantom

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lesperance, Marielle; Martinov, M.; Thomson, R. M., E-mail: rthomson@physics.carleton.ca

Purpose: To investigate dosimetry for ocular brachytherapy for a range of eye plaque models containing{sup 103}Pd, {sup 125}I, or {sup 131}Cs seeds with model-based dose calculations. Methods: Five representative plaque models are developed based on a literature review and are compared to the standardized COMS plaque, including plaques consisting of a stainless steel backing and acrylic insert, and gold alloy backings with: short collimating lips and acrylic insert, no lips and silicone polymer insert, no lips and a thin acrylic layer, and individual collimating slots for each seed within the backing and no insert. Monte Carlo simulations are performed usingmore » the EGSnrc user-code BrachyDose for single and multiple seed configurations for the plaques in water and within an eye model (including nonwater media). Simulations under TG-43 assumptions are also performed, i.e., with the same seed configurations in water, neglecting interseed and plaque effects. Maximum and average doses to ocular structures as well as isodose contours are compared for simulations of each radionuclide within the plaque models. Results: The presence of the plaque affects the dose distribution substantially along the plaque axis for both single seed and multiseed simulations of each plaque design in water. Of all the plaque models, the COMS plaque generally has the largest effect on the dose distribution in water along the plaque axis. Differences between doses for single and multiple seed configurations vary between plaque models and radionuclides. Collimation is most substantial for the plaque with individual collimating slots. For plaques in the full eye model, average dose in the tumor region differs from those for the TG-43 simulations by up to 10% for{sup 125}I and {sup 131}Cs, and up to 17% for {sup 103}Pd, and in the lens region by up to 29% for {sup 125}I, 34% for {sup 103}Pd, and 28% for {sup 131}Cs. For the same prescription dose to the tumor apex, the lowest doses to

Experimental measurements and Monte Carlo simulations of dose perturbation around a nonradioactive brachytherapy seed due to 6- and 18-MV photons.

PubMed

Steinman, James Paul; Bakhtiari, Mohammad; Malhotra, Harish Kumar

2012-01-01

Radioactive seeds used in permanent prostate brachytherapy are composed of high-Z metals and may exceed 100 in a patient. If supplemental external beam treatment is administered afterward, the seeds may cause substantial dose perturbation, which is being investigated in this article. Film measurements using 6-MV beam were primarily carried out using Kodak XV2 film layered above and below a nonradioactive iodine-125 ((125)I) seed. Monte Carlo simulations were carried out using DOSXYZnrc. Other experimental comparisons looked at changing beam energy, depth, and field size, including two opposing fields' pair. Effect of multiple seeds spatially spaced 0.5cm vertically was also studied. For a single (125)I seed, on XV film, there is a localized dose enhancement of 6.3% upstream and -10.9% downstream. With two opposing fields, a cold spot around the seed of ∼3% was noticed. Increasing beam energy and field size decreased the magnitude of this effect, whereas the effect was found to increase with the increasing Z of material. DOSXYZnrc and EBT-2 film verified maximum dose enhancement of +15% upstream and -20% downstream of the (125)I seed surface. In general, the dose perturbation because of the seeds was spatially limited to ∼2mm upstream and ∼5mm downstream to the incident beam. Similar to other heterogeneities, the seeds perturbation depends on incident beam energy, field size, and its Z. With multiple seeds spatially apart and multiple radiation fields routinely used in external beam radiotherapy, the cumulative effect may not result in clinically significant dose perturbation. Copyright © 2012 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

Alpha 1-Adrenoceptor Blocker May Improve Not Only Voiding But Also Storage Lower Urinary Tract Symptoms Caused by 125I Brachytherapy for Prostate Cancer

PubMed Central

Aoki, Yoshitaka; Ito, Hideaki; Miwa, Yoshiji; Akino, Hironobu; Shioura, Hiroki; Kimura, Hirohiko; Yokoyama, Osamu

2014-01-01

Purpose. To assess changes in lower urinary tract symptoms (LUTS) within 1 year after brachytherapy in patients receiving alpha 1-adrenoceptor antagonists. Methods. We retrospectively evaluated 116 patients who underwent 125I prostate brachytherapy in our institute. Seventy-one patients were treated with a combination of external beam radiation therapy and brachytherapy. Alpha 1-adrenoceptor antagonists were prescribed to all patients after brachytherapy. International Prostate Symptom Score (IPSS) forms and postvoid residual urine volume were recorded at all follow-up visits. Results. Forty-nine patients were given tamsulosin hydrochloride, 32 were given silodosin hydrochloride, and 35 were given naftopidil for up to 6 months after seed implantation. Patients given tamsulosin or naftopidil tended to show a higher peak IPSS and slower recovery to baseline values than those given silodosin. The patients given naftopidil showed an insufficient recovery in storage symptoms in naftopidil group in comparison with tamsulosin group at 3 months and with silodosin group at 6 and 9 months. Conclusions. In the management of LUT after brachytherapy, silodosin may provide a more favorable improvement. Silodosin and tamsulosin may have an advantage in improving not only voiding but also storage lower urinary tract symptoms after brachytherapy. PMID:25006516

Dosimetric intercomparison of permanent Ho-166 seed's implants and HDR Ir-192 brachytherapy in breast cancer.

PubMed

de Campos, Tarcisio Passos Ribeiro; Nogueira, Luciana Batista; Trindade, Bruno; Cuperschmid, Ethel Mizrahy

2016-01-01

To provide a comparative dosimetric analysis of permanent implants of Ho(166)-seeds and temporary HDR Ir(192)-brachytherapy through computational simulation. Brachytherapy with Ir(192)-HDR or LDR based on temporary wires or permanent radioactive seed implants can be used as dose reinforcement for breast radiation therapy. Permanent breast implants have not been a practical clinical routine; although, I(125) and Pd(103)-seeds have already been reported. Biodegradable Ho(166)-ceramic-seeds have been addressed recently. Simulations of implants of nine Ho(166)-seeds and equivalent with HDR Ir(192)-brachytherapy were elaborated in MCNP5, shaped in a computational multivoxel simulator which reproduced a female thorax phantom. Spatial dose rate distributions and dose-volume histograms were generated. Protocol's analysis involving exposure time, seed's activities and dose were performed. Permanent Ho(166)-seed implants presented a maximum dose rate per unit of contained activity (MDR) of 1.1601 μGy h(-1) Bq(-1); and, a normalized MDR in standard points (8 mm, equidistant to 03-seeds - SP1, 10 mm - SP2) of 1.0% (SP1) and 0.5% (SP2), respectively. Ir(192)-brachytherapy presented MDR of 4.3945 × 10(-3) μGy h(-1) Bq(-1); and, 30% (SP1), and 20% (SP2). Therefore, seed's implant activities of 333 MBq (Ho(166)) and 259 GBq (Ir(192)) produced prescribed doses of 58 Gy (SP1; 5d) and 56 Gy (SP1, 5 fractions, 6 min), respectively. Breast Ho(166)-implants of 37-111 MBq are attractive due to the high dose rate near 6-10 mm from seeds, equivalent to Ir(192)-brachytherapy of 259 GBq (3 fractions, 6 min) providing similar dose in standard points at a week; however, with spatial dose distribution better confined. The seed positioning can be adjusted for controlling the breast tumor, in stages I and II, in flat and deep tumors, without any breast volumetric limitation.

Pretreatment Nomogram to Predict the Risk of Acute Urinary Retention After I-125 Prostate Brachytherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roeloffzen, Ellen M., E-mail: e.m.a.roeloffzen@umcutrecht.nl; Vulpen, Marco van; Battermann, Jan J.

Purpose: Acute urinary retention (AUR) after iodine-125 (I-125) prostate brachytherapy negatively influences long-term quality of life and therefore should be prevented. We aimed to develop a nomogram to preoperatively predict the risk of AUR. Methods: Using the preoperative data of 714 consecutive patients who underwent I-125 prostate brachytherapy between 2005 and 2008 at our department, we modeled the probability of AUR. Multivariate logistic regression analysis was used to assess the predictive ability of a set of pretreatment predictors and the additional value of a new risk factor (the extent of prostate protrusion into the bladder). The performance of the finalmore » model was assessed with calibration and discrimination measures. Results: Of the 714 patients, 57 patients (8.0%) developed AUR after implantation. Multivariate analysis showed that the combination of prostate volume, IPSS score, neoadjuvant hormonal treatment and the extent of prostate protrusion contribute to the prediction of AUR. The discriminative value (receiver operator characteristic area, ROC) of the basic model (including prostate volume, International Prostate Symptom Score, and neoadjuvant hormonal treatment) to predict the development of AUR was 0.70. The addition of prostate protrusion significantly increased the discriminative power of the model (ROC 0.82). Calibration of this final model was good. The nomogram showed that among patients with a low sum score (<18 points), the risk of AUR was only 0%-5%. However, in patients with a high sum score (>35 points), the risk of AUR was more than 20%. Conclusion: This nomogram is a useful tool for physicians to predict the risk of AUR after I-125 prostate brachytherapy. The nomogram can aid in individualized treatment decision-making and patient counseling.« less

A comparison study on various low energy sources in interstitial prostate brachytherapy.

PubMed

Bakhshabadi, Mahdi; Ghorbani, Mahdi; Khosroabadi, Mohsen; Knaup, Courtney; Meigooni, Ali S

2016-02-01

Low energy sources are routinely used in prostate brachytherapy. (125)I is one of the most commonly used sources. Low energy (131)Cs source was introduced recently as a brachytherapy source. The aim of this study is to compare dose distributions of (125)I, (103)Pd, and (131)Cs sources in interstitial brachytherapy of prostate. ProstaSeed (125)I brachytherapy source was simulated using MCNPX Monte Carlo code. Additionally, two hypothetical sources of (103)Pd and (131)Cs were simulated with the same geometry as the ProstaSeed (125)I source, while having their specific emitted gamma spectra. These brachytherapy sources were simulated with distribution of forty-eight seeds in a phantom including prostate. The prostate was considered as a sphere with radius of 1.5 cm. Absolute and relative dose rates were obtained in various distances from the source along the transverse and longitudinal axes inside and outside the tumor. Furthermore, isodose curves were plotted around the sources. Analyzing the initial dose profiles for various sources indicated that with the same time duration and air kerma strength, (131)Cs delivers higher dose to tumor. However, relative dose rate inside the tumor is higher and outside the tumor is lower for the (103)Pd source. The higher initial absolute dose in cGy/(h.U) of (131)Cs brachytherapy source is an advantage of this source over the others. The higher relative dose inside the tumor and lower relative dose outside the tumor for the (103)Pd source are advantages of this later brachytherapy source. Based on the total dose the (125)I source has advantage over the others due to its longer half-life.

[Application of (125)I seeds combined with biliary stent implantation in the treatment of malignant obstructive jaundice].

PubMed

Wang, T; Liu, S; Zheng, Y B; Song, X P; Jiang, W J; Sun, B L; Wang, L G

2016-03-23

To study the feasibility and therapeutic effect of the application of (125)I seeds combined with biliary stent implantation on the treatment of malignant obstructive jaundice. Fifty patients with malignant obstructive jaundice treated from September 2010 to February 2013 in Yantai Yuhuangding Hospital were included in this study. Among them, 24 patients received biliary stent implantation combined with (125)I seeds intraluminal brachytherapy as experimental group, and 26 were treated by biliary stent implantation as control group.The total bilirubin, direct bilirubin and tumor markers (CA-199, CA-242, CEA) before and after surgery, the biliary stent patency status was assessed, and the survival time was evaluated. The 24 patients in experimental group were implanted with 30 (125)I seeds successfully in a total of 450 seeds. Jaundice was improved greatly in both groups. The CA-199 and CA-242 after treatment in the experimental group were significantly decreased than that before treatment (P=0.003 and P=0.004). CEA was also decreased, but showed no statistical significance (P>0.05). There were no significant improvement comparing the CA-199, CA-242 and CEA before and 2 months after surgery in the control group (P>0.05). The rate of biliary stent patency was 83.3% (20/24) in the experimental group and 57.7% (15/26) in the control group (P=0.048). The mean biliary stent patency time in the experimental group was 9.84 months (range 1-15.5 months). The mean biliary stent patency time in the control group was 5.57 months (range 0.8-9 months). There was a significant difference between the two groups (P=0.018). The median survival time was 10.2 months in the experimental group and 5.4 months in the control group (P<0.05). (125)I seeds combined with biliary stent implantation can inhibit the proliferation of vascular endothelial cells and the growth of tumor effectively, and can prolong the biliary stent patency time and the survival time obviously for patients with

Experimental and Monte Carlo measurements of dose perturbation around a non-radioactive brachytherapy seed in external beam radiotherapy

NASA Astrophysics Data System (ADS)

Steinman, James P.

I-125 seeds used in permanent prostate brachytherapy are composed of high-Z metals and may number from 40 to over 100 in a typical implant. If any supplemental external beam treatment is administered afterward (as for salvaging failed brachytherapy treatment), it is possible that the seeds may cause substantial dose perturbation which will depend on numerous factors (photon energy, depth, field size, number of seeds, etc.) and this effect needs to be thoroughly investigated. Film measurements were primarily done using Kodak XV2 layered above and below a non-radioactive I-125 seed placed in a groove on a Lucite plate with 5 cm buildup and 10 cm backscatter added at 95 cm SSD. The phantom was irradiated with and without seed with 6 MV photons for a 1 x 1 cm2 field size. Monte Carlo simulations were carried out using DOSXYZnrc using the same parameters and compared with Gafchromic EBT2 film. Other comparisons looked at changing energy, depth, and field size in both with and without seeds configuration. This study was further extended to include metals of various Z of the seed's dimensions and also looked into effect of 3 seeds spaced 0.5 cm vertically. Another measurement was done using two opposing fields using single as well as 3 seed configuration to see whether the dose enhancement and attenuation cancel out in multi-field treatments which is the norm clinically in a prostate treatment. For a single I-125 seed, on XV film a localized dose enhancement of 6.3% upstream and -10.9% downstream was noticed. With three seeds, this effect did not change. With two opposing fields, a cold spot around the seed of ~3% was noticed from film measurements. Increasing energy and field size decreased the effect while increase in Z of material greatly increased the effect. Increasing depth appeared to have no effect. DOSXYZnrc and EBT2 film verified maximum dose enhancement of +15% upstream and -20% downstream of the I-125 seed surface. In general, the range of the effect was

Dosimetry for 131Cs and 125I seeds in solid water phantom using radiochromic EBT film.

PubMed

Chiu-Tsao, Sou-Tung; Napoli, John J; Davis, Stephen D; Hanley, Joseph; Rivard, Mark J

2014-09-01

were 1.053±0.014 and 0.924±0.016cGyU(-1)h(-1) for (131)Cs and (125)I seed, respectively. The radial dose functions obtained with EBT film measurements and Monte Carlo simulations were plotted for radial distances up to 5cm, and agreed within the uncertainty of the two methods. The 2D anisotropy functions obtained with both methods also agreed within their uncertainties. EBT film dosimetry in a Solid Water phantom is a viable method for measuring (131)Cs (model CS-1 Rev2) and (125)I (model 6711) brachytherapy seed dose distributions with submillimeter resolution. With the Solid Water to liquid water correction factors generated from Monte Carlo simulations, the measured TG-43 dosimetry parameters in liquid water for these two seed models were found to be in good agreement with those in the literature. Copyright © 2014 Elsevier Ltd. All rights reserved.

A comparison study on various low energy sources in interstitial prostate brachytherapy

PubMed Central

Bakhshabadi, Mahdi; Ghorbani, Mahdi; Knaup, Courtney; Meigooni, Ali S.

2016-01-01

Purpose Low energy sources are routinely used in prostate brachytherapy. 125I is one of the most commonly used sources. Low energy 131Cs source was introduced recently as a brachytherapy source. The aim of this study is to compare dose distributions of 125I, 103Pd, and 131Cs sources in interstitial brachytherapy of prostate. Material and methods ProstaSeed 125I brachytherapy source was simulated using MCNPX Monte Carlo code. Additionally, two hypothetical sources of 103Pd and 131Cs were simulated with the same geometry as the ProstaSeed 125I source, while having their specific emitted gamma spectra. These brachytherapy sources were simulated with distribution of forty-eight seeds in a phantom including prostate. The prostate was considered as a sphere with radius of 1.5 cm. Absolute and relative dose rates were obtained in various distances from the source along the transverse and longitudinal axes inside and outside the tumor. Furthermore, isodose curves were plotted around the sources. Results Analyzing the initial dose profiles for various sources indicated that with the same time duration and air kerma strength, 131Cs delivers higher dose to tumor. However, relative dose rate inside the tumor is higher and outside the tumor is lower for the 103Pd source. Conclusions The higher initial absolute dose in cGy/(h.U) of 131Cs brachytherapy source is an advantage of this source over the others. The higher relative dose inside the tumor and lower relative dose outside the tumor for the 103Pd source are advantages of this later brachytherapy source. Based on the total dose the 125I source has advantage over the others due to its longer half-life. PMID:26985200

Characterization of the PTW SourceCheck ionization chamber with the Valencia lodgment for (125)I seed verification.

PubMed

Tornero-López, Ana M; Torres Del Río, Julia; Ruiz, Carmen; Perez-Calatayud, Jose; Guirado, Damián; Lallena, Antonio M

2015-12-01

In brachytherapy using (125)I seed implants, a verification of the air kerma strength of the sources used is required. Typically, between 40 and 100 seeds are implanted. Checking all of them is unaffordable, especially when seeds are disposed in sterile cartridges. Recently, a new procedure allowing the accomplishment of the international recommendations has been proposed for the seedSelectron system of Elekta Brachytherapy. In this procedure, the SourceCheck ionization chamber is used with a special lodgment (Valencia lodgment) that allows to measure up to 10 seeds simultaneously. In this work we analyze this procedure, showing the feasibility of the approximations required for its application, as well as the effect of the additional dependence with the air density that shows the chamber model used. Uncertainty calculations and the verification of the approximation needed to obtain a calibration factor for the Valencia lodgment are carried out. The results of the present work show that the chamber dependence with the air density is the same whether the Valencia lodgment is used or not. On the contrary, the chamber response profile is influenced by the presence of the lodgment. The determination of this profile requires various measurements due to the nonnegligible variability found between different experiments. If it is considered, the uncertainty in the determination of the air-kerma strength increases from 0.5% to 1%. Otherwise, a systematic additional uncertainty of 1% would occur. This could be relevant for the comparison between user and manufacturer measurements that is mandatory in the case studied here. Copyright © 2015 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

A digital model individual template and CT-guided 125I seed implants for malignant tumors of the head and neck.

PubMed

Huang, Ming-Wei; Liu, Shu-Ming; Zheng, Lei; Shi, Yan; Zhang, Jie; Li, Yan-Sheng; Yu, Guang-Yan; Zhang, Jian-Guo

2012-11-01

To enhance the accuracy of radioactive seed implants in the head and neck, a digital model individual template, containing information simultaneously on needle pathway and facial features, was designed to guide implantation with CT imaging. Thirty-one patients with recurrent and local advanced malignant tumors of head and neck after prior surgery and radiotherapy were involved in this study. Before (125)I implants, patients received CT scans based on 0.75mm thickness. And the brachytherapy treatment planning system (BTPS) software was used to make the implantation plan based on the CT images. Mimics software and Geomagic software were used to read the data containing CT images and implantation plan, and to design the individual template. Then the individual template containing the information of needle pathway and face features simultaneously was made through rapid prototyping (RP) technique. All patients received (125)I seeds interstitial implantation under the guide of the individual template and CT. The individual templates were positioned easily and accurately, and were stable. After implants, treatment quality evaluation was made by CT and TPS. The seeds and dosages distribution (D(90),V(100),V(150)) were well meet the treatment requirement. Clinical practice confirms that this approach can facilitate easier and more accurate implantation.

SU-E-T-123: Anomalous Altitude Effect in Permanent Implant Brachytherapy Seeds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Watt, E; Spencer, DP; Meyer, T

Purpose: Permanent seed implant brachytherapy procedures require the measurement of the air kerma strength of seeds prior to implant. This is typically accomplished using a well-type ionization chamber. Previous measurements (Griffin et al., 2005; Bohm et al., 2005) of several low-energy seeds using the air-communicating HDR 1000 Plus chamber have demonstrated that the standard temperature-pressure correction factor, P{sub TP}, may overcompensate for air density changes induced by altitude variations by up to 18%. The purpose of this work is to present empirical correction factors for two clinically-used seeds (IsoAid ADVANTAGE™ {sup 103}Pd and Nucletron selectSeed {sup 125}I) for which empiricalmore » altitude correction factors do not yet exist in the literature when measured with the HDR 1000 Plus chamber. Methods: An in-house constructed pressure vessel containing the HDR 1000 Plus well chamber and a digital barometer/thermometer was pumped or evacuated, as appropriate, to a variety of pressures from 725 to 1075 mbar. Current measurements, corrected with P{sub TP}, were acquired for each seed at these pressures and normalized to the reading at ‘standard’ pressure (1013.25 mbar). Results: Measurements in this study have shown that utilization of P{sub TP} can overcompensate in the corrected current reading by up to 20% and 17% for the IsoAid Pd-103 and the Nucletron I-125 seed respectively. Compared to literature correction factors for other seed models, the correction factors in this study diverge by up to 2.6% and 3.0% for iodine (with silver) and palladium respectively, indicating the need for seed-specific factors. Conclusion: The use of seed specific altitude correction factors can reduce uncertainty in the determination of air kerma strength. The empirical correction factors determined in this work can be applied in clinical quality assurance measurements of air kerma strength for two previously unpublished seed designs (IsoAid ADVANTAGE™ {sup

I-125 seed calibration using the SeedSelectron® afterloader: a practical solution to fulfill AAPM-ESTRO recommendations

PubMed Central

Perez-Calatayud, Jose; Richart, Jose; Guirado, Damián; Pérez-García, Jordi; Rodríguez, Silvia; Santos, Manuel

2012-01-01

Purpose SeedSelectron® v1.26b (Nucletron BV, The Netherlands) is an afterloader system used in prostate interstitial permanent brachytherapy with I-125 selectSeed seeds. It contains a diode array to assay all implanted seeds. Only one or two seeds can be extracted during the surgical procedure and assayed using a well chamber to check the manufacturer air-kerma strength (SK) and to calibrate the diode array. Therefore, it is not feasible to assay 5–10% seeds as required by the AAPM-ESTRO. In this study, we present a practical solution of the SeedSelectron® users to fulfill the AAPM- ESTRO recommendations. Material and methods The method is based on: a) the SourceCheck® well ionization chamber (PTW, Germany) provided with a PTW insert; b) n = 10 selectSeed from the same batch and class as the seeds for the implant; c) the Nucletron insert to accommodate the n = 10 seeds on the SourceCheck® and to measure their averaged SK. Results for 56 implants have been studied comparing the SK value from the manufacturer with the one obtained with the n = 10 seeds using the Nucletron insert prior to the implant and with the SK of just one seed measured with the PTW insert during the implant. Results We are faced with SK deviation for individual seeds up to 7.8%. However, in the majority of cases SK is in agreement with the manufacturer value. With the method proposed using the Nucletron insert, the large deviations of SK are reduced and for 56 implants studied no deviation outside the range of the class were found. Conclusions The new Nucletron insert and the proposed procedure allow to evaluate the SK of the n = 10 seeds prior to the implant, fulfilling the AAPM-ESTRO recommendations. It has been adopted by Nucletron to be extended to seedSelectron® users under request. PMID:23346136

Photoacoustic imaging of prostate brachytherapy seeds with transurethral light delivery

NASA Astrophysics Data System (ADS)

Lediju Bell, Muyinatu A.; Guo, Xiaoyu; Song, Danny Y.; Boctor, Emad M.

2014-03-01

We present a novel approach to photoacoustic imaging of prostate brachytherapy seeds utilizing an existing urinary catheter for transurethral light delivery. Two canine prostates were surgically implanted with brachyther- apy seeds under transrectal ultrasound guidance. One prostate was excised shortly after euthanasia and fixed in gelatin. The second prostate was imaged in the native tissue environment shortly after euthanasia. A urinary catheter was inserted in the urethra of each prostate. A 1-mm core diameter optical fiber coupled to a 1064 nm Nd:YAG laser was inserted into the urinary catheter. Light from the fiber was either directed mostly parallel to the fiber axis (i.e. end-fire fire) or mostly 90° to the fiber axis (i.e. side-fire fiber). An Ultrasonix SonixTouch scanner, transrectal ultrasound probe with curvilinear (BPC8-4) and linear (BPL9-5) arrays, and DAQ unit were utilized for synchronized laser light emission and photoacoustic signal acquisition. The implanted brachytherapy seeds were visualized at radial distances of 6-16 mm from the catheter. Multiple brachytherapy seeds were si- multaneously visualized with each array of the transrectal probe using both delay-and-sum (DAS) and short-lag spatial coherence (SLSC) beamforming. This work is the first to demonstrate the feasibility of photoacoustic imaging of prostate brachytherapy seeds using a transurethral light delivery method.

Preventive effects of 125I seeds on benign restenosis following esophageal stent implantation in a dog model

PubMed Central

GAN, ZHEN; JING, JIAN; ZHU, GUANGYU; QIN, YONGLIN; TENG, GAOJUN; GUO, JINHE

2015-01-01

The present study aimed to evaluate the effects of iodine-125 (125I) seeds on the proliferation of primary esophageal fibroblasts in dogs, and to assess the safety and preventive efficacy of 125I seed-pre-loaded esophageal stents in benign restenosis following implantation. Primary fibroblasts were cultured with various 125I seed activities, which were then evaluated using cell proliferation and apoptosis assays as well as cell cycle analysis using Annexin V/propidium iodide (PI) double staining and PI staining. Prior to sacrification, animals were submitted to esophageal radiography under digital subtraction angiography. Esophageal tissues were collected and examined for macroscopic, microscopic and pathological alterations. The results demonstrated a significant and dose-dependent inhibition of fibroblast proliferation and increased apoptosis following exposure to 125I seeds. G0/G1 fibroblast populations increased in a dose-dependent manner following treatment with 125I seeds, in contrast to cells in S phase. Four weeks following implantation, α-smooth muscle actin and proliferating cell nuclear antigen expression levels in the experimental group were significantly lower compared with those in the control group; in addition, eight weeks following implantation, esophageal inner diameters were increased in the experimental group. 125I seeds inhibited proliferation of dog esophageal fibroblasts via cell cycle arrest and apoptosis. In conclusion, 125I seed-pre-loaded esophageal stents inhibited benign hyperplasia in the upper edge of the stent to a certain extent, which relieved benign restenosis following implantation with a good safety profile. PMID:25543838

Radioactive seed migration following parotid gland interstitial brachytherapy.

PubMed

Fan, Yi; Huang, Ming-Wei; Zhao, Yi-Jiao; Gao, Hong; Zhang, Jian-Guo

To evaluate the incidence and associated factors of pulmonary seed migration after parotid brachytherapy using a novel migrated seed detection technique. Patients diagnosed with parotid cancer who underwent permanent parotid brachytherapy from January 2006 to December 2011 were reviewed retrospectively. Head and neck CT scans and chest X-rays were evaluated during routine follow-up. Mimics software and Geomagic Studio software were used for seed reconstruction and migrated seed detection from the original implanted region, respectively. Postimplant dosimetry analysis was performed after seeds migration if the seeds were still in their emitting count. Adverse clinical sequelae from seed embolization to the lung were documented. The radioactive seed implants were identified on chest X-rays in 6 patients. The incidence rate of seed migration in 321 parotid brachytherapy patients was 1.87% (6/321) and that of individual seed migration was 0.04% (6/15218 seeds). All migrated seeds were originally from the retromandibular region. No adverse dosimetric consequences were found in the target region. Pulmonary symptoms were not reported by any patient in this study. In our patient set, migration of radioactive seeds with an initial radioactivity of 0.6-0.7 mCi to the chest following parotid brachytherapy was rare. Late migration of a single seed from the central target region did not affect the dosimetry significantly, and patients did not have severe short-term complications. This study proposed a novel technique to localize the anatomical origin of the migrated seeds during brachytherapy. Our evidence suggested that placement of seeds adjacent to blood vessels was associated with an increased likelihood of seed migration to the lungs. Copyright © 2017 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

A Monte Carlo investigation of lung brachytherapy treatment planning

NASA Astrophysics Data System (ADS)

Sutherland, J. G. H.; Furutani, K. M.; Thomson, R. M.

2013-07-01

Iodine-125 (125I) and Caesium-131 (131Cs) brachytherapy have been used in conjunction with sublobar resection to reduce the local recurrence of stage I non-small cell lung cancer compared with resection alone. Treatment planning for this procedure is typically performed using only a seed activity nomogram or look-up table to determine seed strand spacing for the implanted mesh. Since the post-implant seed geometry is difficult to predict, the nomogram is calculated using the TG-43 formalism for seeds in a planar geometry. In this work, the EGSnrc user-code BrachyDose is used to recalculate nomograms using a variety of tissue models for 125I and 131Cs seeds. Calculated prescription doses are compared to those calculated using TG-43. Additionally, patient CT and contour data are used to generate virtual implants to study the effects that post-implant deformation and patient-specific tissue heterogeneity have on perturbing nomogram-derived dose distributions. Differences of up to 25% in calculated prescription dose are found between TG-43 and Monte Carlo calculations with the TG-43 formalism underestimating prescription doses in general. Differences between the TG-43 formalism and Monte Carlo calculated prescription doses are greater for 125I than for 131Cs seeds. Dose distributions are found to change significantly based on implant deformation and tissues surrounding implants for patient-specific virtual implants. Results suggest that accounting for seed grid deformation and the effects of non-water media, at least approximately, are likely required to reliably predict dose distributions in lung brachytherapy patients.

Clinical Study on Using 125I Seeds Articles Combined with Biliary Stent Implantation in the Treatment of Malignant Obstructive Jaundice.

PubMed

Wang, Tao; Liu, Sheng; Zheng, Yan-Bo; Song, Xue-Peng; Sun, Bo-Lin; Jiang, Wen-Jin; Wang, Li-Gang

2017-08-01

Aim: To study the feasibility and curative effect of 125 I seeds articles combined with biliary stent implantation in the treatment of malignant obstructive jaundice. Patients and Methods: Fifty patients with malignant obstructive jaundice were included. Twenty-four were treated by biliary stent implantation combined with intraluminal brachytherapy by 125 I seeds articles as the experimental group, while the remaining 26 were treated by biliary stent implantation only as the control group. The goal of this study was to evaluate total bilirubin, direct bilirubin and tumor markers (cancer antigen (CA)-199, CA-242 and carcinoembryonic antigen (CEA)), as well as biliary stent patency status and survival time before and after surgery. Results: Jaundice improved greatly in both groups. The decreases of CA-199 and CA-242 had statistical significance (p=0.003 and p=0.004) in the experimental group. The ratio of biliary stent patency was 83.3% (20/24) in the experimental group and 57.7% (15/26) in the control group (p=0.048). The biliary stent patency time in the experimental group was 1~15.5 (mean=9.84) months. The biliary stent patency time in the control group was 0.8~9 (mean=5.57) months, which was statistically significant (p=0.018). The median survival time was 10.2 months in the experimental group, while 5.4 months in control group (p<0.05). Conclusion: 125 I seeds articles combined with biliary stent implantation significantly prolongs biliary stent patency time and survival time for patients with malignant obstructive jaundice possibly by inhibiting the proliferation of vascular endothelial cells and the growth of tumor. Copyright© 2017, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

Dosimetric parameters of three new solid core I‐125 brachytherapy sources

PubMed Central

Solberg, Timothy D.; DeMarco, John J.; Hugo, Geoffrey; Wallace, Robert E.

2002-01-01

Monte Carlo calculations and TLD measurements have been performed for the purpose of characterizing dosimetric properties of new commercially available brachytherapy sources. All sources tested consisted of a solid core, upon which a thin layer of I125 has been adsorbed, encased within a titanium housing. The PharmaSeed BT‐125 source manufactured by Syncor is available in silver or palladium core configurations while the ADVANTAGE source from IsoAid has silver only. Dosimetric properties, including the dose rate constant, radial dose function, and anisotropy characteristics were determined according to the TG‐43 protocol. Additionally, the geometry function was calculated exactly using Monte Carlo and compared with both the point and line source approximations. The 1999 NIST standard was followed in determining air kerma strength. Dose rate constants were calculated to be 0.955±0.005,0.967±0.005, and 0.962±0.005 cGyh−1U−1 for the PharmaSeed BT‐125‐1, BT‐125‐2, and ADVANTAGE sources, respectively. TLD measurements were in excellent agreement with Monte Carlo calculations. Radial dose function, g(r), calculated to a distance of 10 cm, and anisotropy function F(r, θ), calculated for radii from 0.5 to 7.0 cm, were similar among all source configurations. Anisotropy constants, ϕ¯an, were calculated to be 0.941, 0.944, and 0.960 for the three sources, respectively. All dosimetric parameters were found to be in close agreement with previously published data for similar source configurations. The MCNP Monte Carlo code appears to be ideally suited to low energy dosimetry applications. PACS number(s): 87.53.–j PMID:11958652

Treasure of the Past IX: Exposure Standardization of Iodine-125 Seeds Used for Brachytherapy

PubMed Central

Loftus, T. P.

2001-01-01

A method for calibrating iodine-125 seeds in terms of exposure has been established. The standard free-air ionization chamber, used for measuring soft x rays, was chosen for the measurements. Arrays of four to six seeds were used to enhance the ionization-current-to-background-current ratio. Seeds from an array were measured individually in a re-entrant chamber. The quotient of the exposure rate for the array by the sum of the ionization currents in the re-entrant chamber is the calibration factor for the re-entrant chamber. Calibration factors were established for three types of iodine-125 seeds. The overall uncertainty for the seed exposure calibrations is less than 6%. PMID:27500052

The direct biologic effects of radioactive 125I seeds on pancreatic cancer cells PANC-1, at continuous low-dose rates.

PubMed

Wang, Jidong; Wang, Junjie; Liao, Anyan; Zhuang, Hongqing; Zhao, Yong

2009-08-01

The relative biologic effectiveness of model 6711 125I seeds (Ningbo Junan Pharmaceutical Technology Company,Ningbo, China) and their effects on growth, cell cycle, and apoptosis in human pancreatic cancer cell line PANC-1 were examined in the present study. PANC-1 cells were exposed to the absorbed doses of 1, 2, 4, 6, 8, and 10 Gyeither with 125I seeds (initial dose rate, 2.59 cGy=h) or with 60Co g-ray irradiation (dose rate, 221 cGy=min),respectively. Significantly greater numbers of apoptotic PANC-1 cells were detected following the continuouslow-dose-rate (CLDR) irradiation of 125I seeds, compared with cells irradiated with identical doses of 60Co g-ray. The D(0) for 60Co g-ray and 125I seed irradiation were 2.30 and 1.66, respectively. The survival fraction after 125Iseed irradiation was significantly lower than that of 60Co g-ray, with a relative biologic effectiveness of 1.39.PANC-1 cells were dose dependently arrested in the S-phase by 60Co g-rays and in the G2=M phase by 125I seeds,24 hour after irradiation. CLDR irradiation by 125I seeds was more effective in inducing cell apoptosis in PANC-1cells than acute high-dose-rate 60Co g irradiation. Interestingly, CLDR irradiation by 125I seeds can cause PANC-1cell-cycle arrest at the G2=M phase and induce apoptosis, which may be an important mechanism underlying 125Iseed-induced PANC-1 cell inhibition.

Biological effects of low-dose-rate irradiation of pancreatic carcinoma cells in vitro using 125I seeds

PubMed Central

Wang, Zhong-Min; Lu, Jian; Zhang, Li-Yun; Lin, Xiao-Zhu; Chen, Ke-Min; Chen, Zhi-Jin; Liu, Fen-Ju; Yan, Fu-Hua; Teng, Gao-Jun; Mao, Ai-Wu

2015-01-01

AIM: To determine the mechanism of the radiation-induced biological effects of 125I seeds on pancreatic carcinoma cells in vitro. METHODS: SW1990 and PANC-1 pancreatic cancer cell lines were cultured in DMEM in a suitable environment. Gray’s model of iodine-125 (125I) seed irradiation was used. In vitro, exponential phase SW1990, and PANC-1 cells were exposed to 0, 2, 4, 6, and 8 Gy using 125I radioactive seeds, with an initial dose rate of 12.13 cGy/h. A clonogenic survival experiment was performed to observe the ability of the cells to maintain their clonogenic capacity and to form colonies. Cell-cycle and apoptosis analyses were conducted to detect the apoptosis percentage in the SW1990 and PANC-1 cells. DNA synthesis was measured via a tritiated thymidine (3H-TdR) incorporation experiment. After continuous low-dose-rate irradiation with 125I radioactive seeds, the survival fractions at 2 Gy (SF2), percentage apoptosis, and cell cycle phases of the SW1990 and PANC-1 pancreatic cancer cell lines were calculated and compared. RESULTS: The survival fractions of the PANC-1 and SW1990 cells irradiated with 125I seeds decreased exponentially as the dose increased. No significant difference in SF2 was observed between SW1990 and PANC-1 cells (0.766 ± 0.063 vs 0.729 ± 0.045, P < 0.05). The 125I seeds induced a higher percentage of apoptosis than that observed in the control in both the SW1990 and PANC-1 cells. The rate of apoptosis increased with increasing radiation dosage. The percentage of apoptosis was slightly higher in the SW1990 cells than in the PANC-1 cells. Dose-dependent G2/M cell-cycle arrest was observed after 125I seed irradiation, with a peak value at 6 Gy. As the dose increased, the percentage of G2/M cell cycle arrest increased in both cell lines, whereas the rate of DNA incorporation decreased. In the 3H-TdR incorporation experiment, the dosimetry results of both the SW1990 and PANC-1 cells decreased as the radiation dose increased, with a minimum

Dosimetric impact of contouring and image registration variability on dynamic 125I prostate brachytherapy.

PubMed

Westendorp, Hendrik; Surmann, Kathrin; van de Pol, Sandrine M G; Hoekstra, Carel J; Kattevilder, Robert A J; Nuver, Tonnis T; Moerland, Marinus A; Slump, Cornelis H; Minken, André W

The quality of permanent prostate brachytherapy can be increased by addition of imaging modalities in the intraoperative procedure. This addition involves image registration, which inherently has inter- and intraobserver variabilities. We sought to quantify the inter- and intraobserver variabilities in geometry and dosimetry for contouring and image registration and analyze the results for our dynamic 125 I brachytherapy procedure. Five observers contoured 11 transrectal ultrasound (TRUS) data sets three times and 11 CT data sets one time. The observers registered 11 TRUS and MRI data sets to cone beam CT (CBCT) using fiducial gold markers. Geometrical and dosimetrical inter- and intraobserver variabilities were assessed. For the contouring study, structures were subdivided into three parts along the craniocaudal axis. We analyzed 165 observations. Interobserver geometrical variability for prostate was 1.1 mm, resulting in a dosimetric variability of 1.6% for V 100 and 9.3% for D 90 . The geometric intraobserver variability was 0.6 mm with a V 100 of 0.7% and D 90 of 1.1%. TRUS-CBCT registration showed an interobserver variability in V 100 of 2.0% and D 90 of 3.1%. Intraobserver variabilities were 0.9% and 1.6%, respectively. For MRI-CBCT registration, V 100 and D 90 were 1.3% and 2.1%. Intraobserver variabilities were 0.7% and 1.1% for the same. Prostate dosimetry is affected by interobserver contouring and registration variability. The observed variability is smaller than underdosages that are adapted during our dynamic brachytherapy procedure. Copyright © 2017 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

Comparison of Intraoperatively Built Custom Linked Seeds Versus Loose Seed Gun Applicator Technique Using Real-Time Intraoperative Planning for Permanent Prostate Brachytherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zauls, A. Jason; Ashenafi, Michael S.; Onicescu, Georgiana

2011-11-15

Purpose: To report our dosimetric results using a novel push-button seed delivery system that constructs custom links of seeds intraoperatively. Methods and Materials: From 2005 to 2007, 43 patients underwent implantation using a gun applicator (GA), and from 2007 to 2008, 48 patientsunderwent implantation with a novel technique allowing creation of intraoperatively built custom links of seeds (IBCL). Specific endpoint analyses were prostate D90% (pD90%), rV100% > 1.3 cc, and overall time under anesthesia. Results: Final analyses included 91 patients, 43 GA and 48 IBCL. Absolute change in pD90% ({Delta}pD90%) between intraoperative and postoperative plans was evaluated. Using GA method,more » the {Delta}pD90% was -8.1Gy and -12.8Gy for I-125 and Pd-103 implants, respectively. Similarly, the IBCL technique resulted in a {Delta}pD90% of -8.7Gy and -9.8Gy for I-125 and Pd-103 implants, respectively. No statistically significant difference in {Delta}pD90% was found comparing methods. The GA method had two intraoperative and 10 postoperative rV100% >1.3 cc. For IBCL, five intraoperative and eight postoperative plans had rV100% >1.3 cc. For GA, the mean time under anesthesia was 75 min and 87 min for Pd-103 and I-125 implants, respectively. For IBCL, the mean time was 86 and 98 min for Pd-103 and I-125. There was a statistical difference between the methods when comparing mean time under anesthesia. Conclusions: Dosimetrically relevant endpoints were equivalent between the two methods. Currently, time under anesthesia is longer using the IBCL technique but has decreased over time. IBCL is a straightforward brachytherapy technique that can be implemented into clinical practice as an alternative to gun applicators.« less

Prospective study of direct radiation exposure measurements for family members living with patients with prostate (125)I seed implantation: Evidence of radiation safety.

PubMed

Hanada, Takashi; Yorozu, Atsunori; Shinya, Yukiko; Kuroiwa, Nobuko; Ohashi, Toshio; Saito, Shiro; Shigematsu, Naoyuki

2016-01-01

To broaden the current understanding of radiation exposure and risk and to provide concrete evidence of radiation safety related to (125)I seed implantation. Direct radiation exposure measurements were obtained from dosimeters provided to 25 patients who underwent (125)I seed implantation, along with their family members. The estimated lifetime exposure dose and the precaution time for holding children near the patient's chest were calculated in two study periods. During the first and second study period, the mean estimated lifetime exposure doses were, respectively, 7.61 (range: 0.45, 20.21) mSv and 6.84 (range: 0.41, 19.20) mSv for patients, and 0.19 (range: 0.02, 0.54) mSv and 0.25 (range: 0.04, 1.00) mSv for family members. The mean ratios of first and second period measurements were 1.05 (range: 0.44, 3.18) for patients and 1.82 (range: 0.21, 7.04) for family members. The corresponding absolute differences between first and second period measurements were -0.77 (range: -11.40, 7.63) mSv and 0.06 (range: -0.26, 0.79) mSv, respectively. Assuming a dose limit of 1 mSv, the precaution times for holding a child every day of the first and second periods were 250.9 (range: 71.3, 849.4) min and 275.2 (range: 75.0, 883.4) min, respectively. Assuming a dose limit of 0.5 mSv, the corresponding precaution times were 179.0 (range: 35.6, 811.5) min and 178.9 (range: 37.5, 1131.8) min, respectively. Our study demonstrated low radiation exposures to family members of patients undergoing (125)I prostate implantation. It was clear that (125)I seed implantation did not pose a threat to the safety of family members. Copyright © 2016 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

CT, MR, and ultrasound image artifacts from prostate brachytherapy seed implants: The impact of seed size

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robertson, Andrew K. H.; Basran, Parminder S.; Thomas, Steven D.

Purpose: To investigate the effects of brachytherapy seed size on the quality of x-ray computed tomography (CT), ultrasound (US), and magnetic resonance (MR) images and seed localization through comparison of the 6711 and 9011 {sup 125}I sources. Methods: For CT images, an acrylic phantom mimicking a clinical implantation plan and embedded with low contrast regions of interest (ROIs) was designed for both the 0.774 mm diameter 6711 (standard) and the 0.508 mm diameter 9011 (thin) seed models (Oncura, Inc., and GE Healthcare, Arlington Heights, IL). Image quality metrics were assessed using the standard deviation of ROIs between the seeds andmore » the contrast to noise ratio (CNR) within the low contrast ROIs. For US images, water phantoms with both single and multiseed arrangements were constructed for both seed sizes. For MR images, both seeds were implanted into a porcine gel and imaged with pelvic imaging protocols. The standard deviation of ROIs and CNR values were used as metrics of artifact quantification. Seed localization within the CT images was assessed using the automated seed finder in a commercial brachytherapy treatment planning system. The number of erroneous seed placements and the average and maximum error in seed placements were recorded as metrics of the localization accuracy. Results: With the thin seeds, CT image noise was reduced from 48.5 {+-} 0.2 to 32.0 {+-} 0.2 HU and CNR improved by a median value of 74% when compared with the standard seeds. Ultrasound image noise was measured at 50.3 {+-} 17.1 dB for the thin seed images and 50.0 {+-} 19.8 dB for the standard seed images, and artifacts directly behind the seeds were smaller and less prominent with the thin seed model. For MR images, CNR of the standard seeds reduced on average 17% when using the thin seeds for all different imaging sequences and seed orientations, but these differences are not appreciable. Automated seed localization required an average ({+-}SD) of 7.0 {+-} 3

Review of the poster "Dosimetric comparison of gamma knife radiosurgery vs. 125I plaque brachytherapy in a cohort of choroidal melanomas".

PubMed

Odell, Kelly R

2009-01-01

Historically, treatment for choroidal melanomas was surgical enucleation. Currently, treatment methods such as stereotactic radiosurgery and brachytherapy are being used to spare the eye. The poster "Dosimetric Comparison of Gamma Knife Radiosurgery vs. I-125 Plaque Brachytherapy in a Cohort of Choroidal Melanomas" presented at ASTRO 2007 by Anderson et al. provides a comparison of these methods. The dose to disk, fovea and lens in 29 patients from a simulated I-125 treatment and a delivered Gamma Knife radiosurgery was compared. Thirty Gy was prescribed to the 50% Isodose line in the radiosurgery and 85 Gy was prescribed to the apex of the tumor in the I-125 simulation. It was found that the Gamma Knife spares the disk better in 59% of the tumors, including those >or=6.5 mm in height; spares the fovea better in 69% of the tumors, including those >or=5.5 mm; and spares lens better in only 30% of the tumors, with no distinction in size. Tumor location was not taken into account for this study, which could explain the variations in smaller tumors. For larger tumors, gamma knife will protect most organs at risk more effectively. This study shows how a tumor's parameters can be used in selecting treatment modality.

The value of spectral imaging to reduce artefacts in the body after 125 I seed implantation.

PubMed

Liu, Jingang; Wang, Wenjuan; Zhao, Xingsheng; Shen, Zhen; Shao, Weiguang; Wang, Xizhen; Li, Lixin; Wang, Bin

2016-10-01

To explore the value of gemstone spectral imaging (GSI) and metal artefact reduction sequence (MARs) to reduce the artefacts of metal seeds. Thirty-five patients with 125 I seed implantation in their abdomens underwent GSI CT. Six types of monochromatic images and the corresponding MARs images at 60-110 keV (interval of 10 keV) were reconstructed. The differences in the quality of the images of three imaging methods were subjectively assessed by three radiologists. Length of artefacts, the CT value and noise value of tissue adjacent to 125 I seeds, contrast-to-noise ratio (CNR), and artefact index (AI) were recorded. The differences in subjective scoring were statistically significant (t = 10.87, P < 0.001). Images at 70 keV showed the best CNR (0.84 ± 0.17) of tissues adjacent to 125 I seeds, and received the highest subjective score (2.82 ± 0.18). Images at 80 keV had the lowest AI (70.67 ± 19.17). Images at 110 keV had the shortest artefact lengths. High-density metal artefacts in the MARs spectral images were reduced. The length of metal artefacts in images at 110 keV was shorter than that of the polychromatic images and MARs spectral images (t = 3.35, 3.89, P < 0.05). The difference in CNR between MARs spectral images and polychromatic images, and images at 70 keV was statistically significant (t = 3.57, 4.16, P < 0.01). Gemstone spectral imaging technique can reduce metal artefacts of 125 I seeds effectively in CT images, and improve the quality of images, and improve the display of tissues adjacent to 125 I seeds after implantation. MARs technique cannot reduce the artefacts caused by radioactive seeds effectively. © 2016 The Royal Australian and New Zealand College of Radiologists.

Single-nucleotide polymorphisms studied for associations with urinary toxicity from (125)I prostate brachytherapy implants.

PubMed

Usmani, Nawaid; Leong, Nelson; Martell, Kevin; Lan, Lanna; Ghosh, Sunita; Pervez, Nadeem; Pedersen, John; Yee, Don; Murtha, Albert; Amanie, John; Sloboda, Ron; Murray, David; Parliament, Matthew

2014-01-01

To identify clinical, dosimetric, and genetic factors that are associated with late urinary toxicity after a (125)I prostate brachytherapy implant. Genomic DNA from 296 men treated with (125)I prostate brachytherapy monotherapy was extracted from saliva samples for this study. A retrospective database was compiled including clinical, dosimetric, and toxicity data for this cohort of patients. Fourteen candidate single-nucleotide polymorphism (SNPs) from 13 genes (TP53, ERCC2, GSTP1, NOS, TGFβ1, MSH6, RAD51, ATM, LIG4, XRCC1, XRCC3, GSTA1, and SOD2) were tested in this cohort for correlations with toxicity. This study identified 217 men with at least 2 years of followup. Of these, 39 patients developed Grade ≥2 late urinary complications with a transurethral resection of prostate, urethral stricture, gross hematuria, or a sustained increase in their International Prostate Symptom Score. The only clinical or dosimetric factor that was associated with late urinary toxicity was age (p = 0.02). None of the 14 SNPs tested in this study were associated with late urinary toxicity in the univariate analysis. This study identified age as the only variable being associated with late urinary toxicity. However, the small sample size and the candidate gene approach used in this study mean that further investigations are essential. Genome-wide association studies are emerging as the preferred approach for future radiogenomic studies to overcome the limitations from a candidate gene approach. Crown Copyright © 2014. Published by Elsevier Inc. All rights reserved.

Three-dimensional verification of ¹²⁵I seed stability after permanent implantation in the parotid gland and periparotid region.

PubMed

Fan, Yi; Huang, Ming-Wei; Zheng, Lei; Zhao, Yi-Jiao; Zhang, Jian-Guo

2015-11-24

To evaluate seed stability after permanent implantation in the parotid gland and periparotid region via a three-dimensional reconstruction of CT data. Fifteen patients treated from June 2008 to June 2012 at Peking University School and Hospital of Stomatology for parotid gland tumors with postoperative adjunctive (125)I interstitial brachytherapy were retrospectively reviewed in this study. Serial CT data were obtained during follow-up. Mimics and Geomagic Studio software were used for seed reconstruction and stability analysis, respectively. Seed loss and/or migration outside of the treated area were absent in all patients during follow-up (23-71 months). Total seed cluster volume was maximized on day 1 post-implantation due to edema and decreased significantly by an average of 13.5 % (SD = 9.80 %; 95 % CI, 6.82-17.68 %) during the first two months and an average of 4.5 % (SD = 3.60 %; 95 % CI, 2.29-6.29 %) during the next four months. Volume stabilized over the subsequent six months. (125)I seed number and location were stable with a general volumetric shrinkage tendency in the parotid gland and periparotid region. Three-dimensional seed reconstruction of CT images is feasible for visualization and verification of implanted seeds in parotid brachytherapy.

Comparison of 3 different postimplant dosimetry methods following permanent {sup 125}I prostate seed brachytherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marcu, Loredana G., E-mail: loredana@marcunet.com; Faculty of Science, University of Oradea; School of Chemistry and Physics, University of Adelaide, South Australia

2013-10-01

Postimplant dosimetry (PID) after Iodine-125 ({sup 125}I) implant of the prostate should offer a reliable qualitative assessment. So far, there is no consensus regarding the optimum PID method, though the latest literature is in favor of magnetic resonance imaging (MRI). This study aims to simultaneously compare 3 PID techniques: (1) MRI-computed tomography (CT) fusion; (2) ultrasound (US)-CT fusion; and (3) manual target delineation on CT. The study comprised 10 patients with prostate cancer. CT/MR scans with urinary catheters in place for PID were done either on day 0 or day 1 postimplantation. The main parameter evaluated and compared among methodsmore » was target D90. The results show that CT-based D90s are lower than US-CT D90s (median difference,−6.85%), whereas MR-CT PID gives higher D90 than US-CT PID (median difference, 4.25%). Manual contouring on CT images tends to overestimate the prostate volume compared with transrectal ultrasound (TRUS) (median difference, 23.33%), whereas on US images the target is overestimated compared with MR-based contouring (median difference, 13.25%). Although there are certain differences among the results given by various PID techniques, the differences are statistically insignificant for this small group of patients. Any dosimetric comparison between 2 PID techniques should also account for the limitations of each technique, to allow for an accurate quantification of data. Given that PID after permanent radioactive seed implant is mandatory for quality assurance, any imaging method–based PID (MR-CT, US-CT, and CT) available in a radiotherapy department can be indicative of the quality of the procedure.« less

Ocular Response of Choroidal Melanoma With Monosomy 3 Versus Disomy 3 After Iodine-125 Brachytherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marathe, Omkar S.; Wu, Jeffrey; Lee, Steve P.

2011-11-15

Purpose: To report the ocular response of choroidal melanoma with monosomy 3 vs. disomy 3 after {sup 125}I brachytherapy. Methods and Materials: We evaluated patients with ciliochoroidal melanoma managed with fine needle aspiration biopsy immediately before plaque application for {sup 125}I brachytherapy between January 1, 2005 and December 31, 2008. Patients with (1) cytopathologic diagnosis of melanoma, (2) melanoma chromosome 3 status identified by fluorescence in situ hybridization, and (3) 6 or more months of follow-up after brachytherapy were sorted by monosomy 3 vs. disomy 3 and compared by Kruskal-Wallis test. Results: Among 40 ciliochoroidal melanomas (40 patients), 15 hadmore » monosomy 3 and 25 had disomy 3. Monosomy 3 melanomas had a median greatest basal diameter of 12.00 mm and a median tumor thickness of 6.69 mm before brachytherapy; at a median of 1.75 years after brachytherapy, median thickness was 3.10 mm. Median percentage decrease in tumor thickness was 48.3%. Disomy 3 melanomas had a median greatest basal diameter of 10.00 mm and median tumor thickness of 3.19 mm before brachytherapy; at a median of 2.00 years after brachytherapy, median tumor thickness was 2.37 mm. The median percentage decrease in tumor thickness was 22.7%. Monosomy 3 melanomas were statistically greater in size than disomy 3 melanomas (p < 0.001) and showed a greater decrease in tumor thickness after brachytherapy (p = 0.006). Conclusion: In this study, ciliochoroidal melanomas with monosomy 3 were significantly greater in size than disomy 3 melanoma and showed a significantly greater decrease in thickness at a median of 1.75 years after brachytherapy. The greater decrease in monosomy 3 melanoma thickness after brachytherapy is consistent with other malignancies in which more aggressive pathology has been shown to be associated with a greater initial response to radiotherapy.« less

Rectourethral fistula following LDR brachytherapy.

PubMed

Borchers, Holger; Pinkawa, Michael; Donner, Andreas; Wolter, Timm P; Pallua, Norbert; Eble, Michael J; Jakse, Gerhard

2009-01-01

Modern LDR brachytherapy has drastically reduced rectal toxicity and decreased the occurrence of rectourethral fistulas to <0.5% of patients. Therefore, symptoms of late-onset sequelae are often ignored initially. These fistulas cause severe patient morbidity and require interdisciplinary treatment. We report on the occurrence and management of a rectourethral fistula which occurred 4 years after (125)I seed implantation. Copyright 2009 S. Karger AG, Basel.

CT-Guided Radioactive {sup 125}I Seed Implantation Therapy of Symptomatic Retroperitoneal Lymph Node Metastases

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Zhongmin, E-mail: wzm0722@hotmail.com; Lu, Jian; Gong, Ju

2013-04-12

PurposeThis study explored the clinical efficacy of CT-guided radioactive {sup 125}I seed implantation in treating patients with symptomatic retroperitoneal lymph node metastases.MethodsTwenty-five patients with pathologically confirmed malignant tumors received CT-guided radioactive {sup 125}I seed implantation to treat metastatic lymph nodes. The diameter of the metastatic lymph nodes ranged from 1.5 to 4.5 cm. Treatment planning system (TPS) was used to reconstruct the three-dimensional image of the tumor and then calculate the corresponding quantity and distribution of {sup 125}I seeds.ResultsFollow-up period for this group of patients was 2–30 months, and median time was 16 months. Symptoms of refractory pain were significantly resolved postimplantationmore » (P < 0.05), and Karnofsky score rose dramatically (P < 0.05). Most patients reported pain relief 2–5 days after treatment. Follow-up imaging studies were performed 2 months later, which revealed CR in 7 patients, PR in 13 patients, SD in 3 patients, and PD in 2 patients. The overall effective rate (CR + PR) was 80 %. Median survival time was 25.5 months. Seven patients died of recurrent tumor; 16 patients died of multiorgan failure or other metastases. Two patients survived after 30 months follow-up. Two patients reported localized skin erythema 1 week postimplantation, which disappeared after topical treatment.ConclusionsCT-guided radioactive {sup 125}I seed implantation, which showed good palliative pain relief with acceptable short-term effects, has proved in our study to be a new, safe, effective, and relatively uncomplicated treatment option for symptomatic retroperitoneal metastatic lymph nodes.« less

Advanced Collapsed cone Engine dose calculations in tissue media for COMS eye plaques loaded with I-125 seeds.

PubMed

Morrison, Hali; Menon, Geetha; Larocque, Matthew P; van Veelen, Bob; Niatsetski, Yury; Weis, Ezekiel; Sloboda, Ron S

2018-05-04

To investigate the dose calculation accuracy of the Advanced Collapsed cone Engine (ACE) algorithm for ocular brachytherapy using a COMS plaque loaded with I-125 seeds for two heterogeneous patient tissue scenarios. The Oncura model 6711 I-125 seed and 16 mm COMS plaque were added to a research version (v4.6) of the Oncentra ® Brachy (OcB) treatment planning system (TPS) for dose calculations using ACE. Treatment plans were created for two heterogeneous cases: (a) a voxelized eye phantom comprising realistic eye materials and densities and (b) a patient CT dataset with variable densities throughout the dataset. ACE dose calculations were performed using a high accuracy mode, high-resolution calculation grid matching the imported CT datasets (0.5 × 0.5 × 0.5 mm 3 ), and a user-defined CT calibration curve. The accuracy of ACE was evaluated by replicating the plan geometries and comparing to Monte Carlo (MC) calculated doses obtained using MCNP6. The effects of the heterogeneous patient tissues on the dose distributions were also evaluated by performing the ACE and MCNP6 calculations for the same scenarios but setting all tissues and air to water. Average local percent dose differences between ACE and MC within contoured structures and at points of interest for both scenarios ranged from 1.2% to 20.9%, and along the plaque central axis (CAX) from 0.7% to 7.8%. The largest differences occurred in the plaque penumbra (up to 17%), and at contoured structure interfaces (up to 20%). Other regions in the eye agreed more closely, within the uncertainties of ACE dose calculations (~5%). Compared to that, dose differences between water-based and fully heterogeneous tissue simulations were up to 27%. Overall, ACE dosimetry agreed well with MC in the tumor volume and along the plaque CAX for the two heterogeneous tissue scenarios, indicating that ACE could potentially be used for clinical ocular brachytherapy dosimetry. In general, ACE data matched the fully heterogeneous MC

SU-E-J-233: Effect of Brachytherapy Seed Artifacts in T2 and Proton Density Maps in MR Images

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mashouf, S; University of Toronto, Dept of Radiation Oncology, Toronto, Ontario; Fatemi-Ardekani, A

Purpose: This study aims at investigating the influence of brachytherapy seeds on T2 and proton density (PD) maps generated from MR images. Proton density maps can be used to extract water content. Since dose absorbed in tissue surrounding low energy brachytherapy seeds are highly influenced by tissue composition, knowing the water content is a first step towards implementing a heterogeneity correction algorithm using MR images. Methods: An LDR brachytherapy (IsoAid Advantage Pd-103) seed was placed in the middle of an agar-based gel phantom and imaged using a 3T Philips MR scanner with a 168-channel head coil. A multiple echo sequencemore » with TE=20, 40, 60, 80, 100 (ms) with large repetition time (TR=6259ms) was used to extract T2 and PD maps. Results: Seed artifacts were considerably reduced on T2 maps compared to PD maps. The variation of PD around the mean was obtained as −97% to 125% (±1%) while for T2 it was recorded as −71% to 24% (±1%). Conclusion: PD maps which are required for heterogeneity corrections are susceptible to artifacts from seeds. Seed artifacts on T2 maps, however, are significantly reduced due to not being sensitive to B0 field variation.« less

Monte Carlo investigation of I-125 interseed attenuation for standard and thinner seeds in prostate brachytherapy with phantom validation using a MOSFET.

PubMed

Mason, J; Al-Qaisieh, B; Bownes, P; Henry, A; Thwaites, D

2013-03-01

In permanent seed implant prostate brachytherapy the actual dose delivered to the patient may be less than that calculated by TG-43U1 due to interseed attenuation (ISA) and differences between prostate tissue composition and water. In this study the magnitude of the ISA effect is assessed in a phantom and in clinical prostate postimplant cases. Results are compared for seed models 6711 and 9011 with 0.8 and 0.5 mm diameters, respectively. A polymethyl methacrylate (PMMA) phantom was designed to perform ISA measurements in a simple eight-seed arrangement and at the center of an implant of 36 seeds. Monte Carlo (MC) simulation and experimental measurements using a MOSFET dosimeter were used to measure dose rate and the ISA effect. MC simulations of 15 CT-based postimplant prostate treatment plans were performed to compare the clinical impact of ISA on dose to prostate, urethra, rectum, and the volume enclosed by the 100% isodose, for 6711 and 9011 seed models. In the phantom, ISA reduced the dose rate at the MOSFET position by 8.6%-18.3% (6711) and 7.8%-16.7% (9011) depending on the measurement configuration. MOSFET measured dose rates agreed with MC simulation predictions within the MOSFET measurement uncertainty, which ranged from 5.5% to 7.2% depending on the measurement configuration (k = 1, for the mean of four measurements). For 15 clinical implants, the mean ISA effect for 6711 was to reduce prostate D90 by 4.2 Gy (3%), prostate V100 by 0.5 cc (1.4%), urethra D10 by 11.3 Gy (4.4%), rectal D2cc by 5.5 Gy (4.6%), and the 100% isodose volume by 2.3 cc. For the 9011 seed the mean ISA effect reduced prostate D90 by 2.2 Gy (1.6%), prostate V100 by 0.3 cc (0.7%), urethra D10 by 8.0 Gy (3.2%), rectal D2cc by 3.1 Gy (2.7%), and the 100% isodose volume by 1.2 cc. Differences between the MC simulation and TG-43U1 consensus data for the 6711 seed model had a similar impact, reducing mean prostate D90 by 6 Gy (4.2%) and V100 by 0.6 cc (1.8%). ISA causes the delivered dose

A Monte Carlo study of I-125 prostate brachytherapy with gold nanoparticles: dose enhancement with simultaneous rectal dose sparing via radiation shielding.

PubMed

Brivio, D; Nguyen, P L; Sajo, E; Ngwa, W; Zygmanski, P

2017-03-07

We investigate via Monte Carlo simulations a new 125 I brachytherapy treatment technique for high-risk prostate cancer patients via injection of Au nanoparticle (AuNP) directly into the prostate. The purpose of using the nanoparticles is to increase the therapeutic index via two synergistic effects: enhanced energy deposition within the prostate and simultaneous shielding of organs at risk from radiation escaping from the prostate. Both uniform and non-uniform concentrations of AuNP are studied. The latter are modeled considering the possibility of AuNP diffusion after the injection using brachy needles. We study two extreme cases of coaxial AuNP concentrations: centered on brachy needles and centered half-way between them. Assuming uniform distribution of 30 mg g -1 of AuNP within the prostate, we obtain a dose enhancement larger than a factor of 2 to the prostate. Non-uniform concentration of AuNP ranging from 10 mg g -1 and 66 mg g -1 were studied. The higher the concentration in a given region of the prostate the greater is the enhancement therein. We obtain the highest dose enhancement when the brachytherapy needles are coincident with AuNP injection needles but, at the same time, the regions in the tail are colder (average dose ratio of 0.7). The best enhancement uniformity is obtained with the seeds in the tail of the AuNP distribution. In both uniform and non-uniform cases the urethra and rectum receive less than 1/3 dose compared to an analog treatment without AuNP. Remarkably, employing AuNP not only significantly increases dose to the target but also decreases dose to the neighboring rectum and even urethra, which is embedded within the prostate. These are mutually interdependent effects as more enhancement leads to more shielding and vice-versa. Caution must be paid since cold spot or hot spots may be created if the AuNP concentration versus seed position is not properly distributed respect to the seed locations.

A Monte Carlo study of I-125 prostate brachytherapy with gold nanoparticles: dose enhancement with simultaneous rectal dose sparing via radiation shielding

NASA Astrophysics Data System (ADS)

Brivio, D.; Nguyen, P. L.; Sajo, E.; Ngwa, W.; Zygmanski, P.

2017-03-01

We investigate via Monte Carlo simulations a new 125I brachytherapy treatment technique for high-risk prostate cancer patients via injection of Au nanoparticle (AuNP) directly into the prostate. The purpose of using the nanoparticles is to increase the therapeutic index via two synergistic effects: enhanced energy deposition within the prostate and simultaneous shielding of organs at risk from radiation escaping from the prostate. Both uniform and non-uniform concentrations of AuNP are studied. The latter are modeled considering the possibility of AuNP diffusion after the injection using brachy needles. We study two extreme cases of coaxial AuNP concentrations: centered on brachy needles and centered half-way between them. Assuming uniform distribution of 30 mg g-1 of AuNP within the prostate, we obtain a dose enhancement larger than a factor of 2 to the prostate. Non-uniform concentration of AuNP ranging from 10 mg g-1 and 66 mg g-1 were studied. The higher the concentration in a given region of the prostate the greater is the enhancement therein. We obtain the highest dose enhancement when the brachytherapy needles are coincident with AuNP injection needles but, at the same time, the regions in the tail are colder (average dose ratio of 0.7). The best enhancement uniformity is obtained with the seeds in the tail of the AuNP distribution. In both uniform and non-uniform cases the urethra and rectum receive less than 1/3 dose compared to an analog treatment without AuNP. Remarkably, employing AuNP not only significantly increases dose to the target but also decreases dose to the neighboring rectum and even urethra, which is embedded within the prostate. These are mutually interdependent effects as more enhancement leads to more shielding and vice-versa. Caution must be paid since cold spot or hot spots may be created if the AuNP concentration versus seed position is not properly distributed respect to the seed locations.

Impact of target area selection in 125 Iodine seed brachytherapy on locoregional recurrence in patients with non-small cell lung cancer.

PubMed

Yan, Wei-Liang; Lv, Jin-Shuang; Guan, Zhi-Yu; Wang, Li-Yang; Yang, Jing-Kui; Liang, Ji-Xiang

2017-05-01

Computed tomography (CT)-guided percutaneous implantation of 125 Iodine radioactive seeds requires the precise arrangement of seeds by tumor shape. We tested whether selecting target areas, including subclinical areas around tumors, can influence locoregional recurrence in patients with non-small cell lung cancer (NSCLC). We divided 82 patients with NSCLC into two groups. Target areas in group 1 (n = 40) were defined along tumor margins based on lung-window CT. Target areas in group 2 (n = 42) were extended by 0.5 cm in all dimensions outside tumor margins. Preoperative plans for both groups were based on a treatment plan system, which guided 125 I seed implantation. Six months later, patients underwent chest CT to evaluate treatment efficacy (per Response Evaluation Criteria in Solid Tumors version 1). We compared locoregional recurrences between the groups after a year of follow-up. We then used the treatment plan system to extend target areas for group 1 patients by 0.5 cm (defined as group 3 data) and compared these hypothetical group 3 planned seeds with the actual seed numbers used in group 1 patients. All patients successfully underwent implantation; none died during the follow-up period. Recurrence was significantly lower in group 2 than in group 1 ( P  < 0.05). Group 1 patients and group 3 data significantly differed in seed numbers ( P  < 0.01). Our results imply that extending the implantation area for 125 I seeds can decrease recurrence risk by eradicating cancerous lymph-duct blockades within the extended areas. © 2017 The Authors. Thoracic Cancer published by China Lung Oncology Group and John Wiley & Sons Australia, Ltd.

Monte Carlo study of LDR seed dosimetry with an application in a clinical brachytherapy breast implant.

PubMed

Furstoss, C; Reniers, B; Bertrand, M J; Poon, E; Carrier, J-F; Keller, B M; Pignol, J P; Beaulieu, L; Verhaegen, F

2009-05-01

A Monte Carlo (MC) study was carried out to evaluate the effects of the interseed attenuation and the tissue composition for two models of 125I low dose rate (LDR) brachytherapy seeds (Medi-Physics 6711, IBt InterSource) in a permanent breast implant. The effect of the tissue composition was investigated because the breast localization presents heterogeneities such as glandular and adipose tissue surrounded by air, lungs, and ribs. The absolute MC dose calculations were benchmarked by comparison to the absolute dose obtained from experimental results. Before modeling a clinical case of an implant in heterogeneous breast, the effects of the tissue composition and the interseed attenuation were studied in homogeneous phantoms. To investigate the tissue composition effect, the dose along the transverse axis of the two seed models were calculated and compared in different materials. For each seed model, three seeds sharing the same transverse axis were simulated to evaluate the interseed effect in water as a function of the distance from the seed. A clinical study of a permanent breast 125I implant for a single patient was carried out using four dose calculation techniques: (1) A TG-43 based calculation, (2) a full MC simulation with realistic tissues and seed models, (3) a MC simulation in water and modeled seeds, and (4) a MC simulation without modeling the seed geometry but with realistic tissues. In the latter, a phase space file corresponding to the particles emitted from the external surface of the seed is used at each seed location. The results were compared by calculating the relevant clinical metrics V85, V100, and V200 for this kind of treatment in the target. D90 and D50 were also determined to evaluate the differences in dose and compare the results to the studies published for permanent prostate seed implants in literature. The experimental results are in agreement with the MC absolute doses (within 5% for EBT Gafchromic film and within 7% for TLD-100

In vivo photoacoustic imaging of prostate brachytherapy seeds

NASA Astrophysics Data System (ADS)

Lediju Bell, Muyinatu A.; Kuo, Nathanael P.; Song, Danny Y.; Kang, Jin; Boctor, Emad M.

2014-03-01

We conducted an approved canine study to investigate the in vivo feasibility of photoacoustic imaging for intraoperative updates to brachytherapy treatment plans. Brachytherapy seeds coated with black ink were inserted into the canine prostate using methods similar to a human procedure. A transperineal, interstitial, fiber optic light delivery method, coupled to a 1064 nm laser, was utilized to irradiate the prostate and the resulting acoustic waves were detected with a transrectal ultrasound probe. The fiber was inserted into a high dose rate (HDR) brachytherapy needle that acted as a light-diffusing sheath, enabling radial light delivery from the tip of the fiber inside the sheath. The axis of the fiber was located at a distance of 4-9 mm from the long axis of the cylindrical seeds. Ultrasound images acquired with the transrectal probe and post-operative CT images of the implanted seeds were analyzed to confirm seed locations. In vivo limitations with insufficient light delivery within the ANSI laser safety limit (100 mJ/cm2) were overcome by utilizing a short-lag spatial coherence (SLSC) beamformer, which provided average seed contrasts of 20-30 dB for energy densities ranging 8-84 mJ/cm2. The average contrast was improved by up to 20 dB with SLSC beamforming compared to conventional delay-and-sum beamforming. There was excellent agreement between photoacoustic, ultrasound, and CT images. Challenges included visualization of photoacoustic artifacts that corresponded with locations of the optical fiber and hyperechoic tissue structures.

125I Brachytherapy in Locally Advanced Nonsmall Cell Lung Cancer After Progression of Concurrent Radiochemotherapy

PubMed Central

Xiang, Zhanwang; Li, Guohong; Liu, Zhenyin; Huang, Jinhua; Zhong, Zhihui; Sun, Lin; Li, Chuanxing; Zhang, Funjun

2015-01-01

Abstract To investigate the safety and effectiveness of computed tomography (CT)-guided 125I seed implantation for locally advanced nonsmall cell lung cancer (NSCLC) after progression of concurrent radiochemotherapy (CCRT). We reviewed 78 locally advanced NSCLC patients who had each one cycle of first-line CCRT but had progressive disease identified from January 2006 to February 2015 at our institution. A total of 37 patients with 44 lesions received CT-guided percutaneous 125I seed implantation and second-line chemotherapy (group A), while 41 with 41 lesions received second-line chemotherapy (group B). Patients in group A and B received a total of 37 and 41 first cycle of CCRT treatment. The median follow-up was 19 (range 3–36) months. After the second treatment, the total response rate (RR) in tumor response accounted for 63.6% in group A, which was significantly higher than that of group B (41.5%) (P = 0.033). The median progression-free survival time (PFST) was 8.00 ± 1.09 months and 5.00 ± 0.64 months in groups A and B (P = 0.011). The 1-, 2-, and 3-year overall survival (OS) rates for group A were 56.8%, 16.2%, and 2.7%, respectively. For group B, OS rates were 36.6%, 9.8%, and 2.4%, respectively. The median OS time was 14.00 ± 1.82 months and 10.00 ± 1.37 months for groups A and B, respectively (P = 0.059). Similar toxicity reactions were found in both groups. Tumor-related clinical symptoms were significantly reduced and the patients’ quality of life was obviously improved. CT-guided 125I seed implantation proved to be potentially beneficial in treating localized advanced NSCLC; it achieved good local control rates and relieved clinical symptoms without increasing side effects. PMID:26656370

Cluster pattern analysis of energy deposition sites for the brachytherapy sources 103Pd, 125I, 192Ir, 137Cs, and 60Co.

PubMed

Villegas, Fernanda; Tilly, Nina; Bäckström, Gloria; Ahnesjö, Anders

2014-09-21

Analysing the pattern of energy depositions may help elucidate differences in the severity of radiation-induced DNA strand breakage for different radiation qualities. It is often claimed that energy deposition (ED) sites from photon radiation form a uniform random pattern, but there is indication of differences in RBE values among different photon sources used in brachytherapy. The aim of this work is to analyse the spatial patterns of EDs from 103Pd, 125I, 192Ir, 137Cs sources commonly used in brachytherapy and a 60Co source as a reference radiation. The results suggest that there is both a non-uniform and a uniform random component to the frequency distribution of distances to the nearest neighbour ED. The closest neighbouring EDs show high spatial correlation for all investigated radiation qualities, whilst the uniform random component dominates for neighbours with longer distances for the three higher mean photon energy sources (192Ir, 137Cs, and 60Co). The two lower energy photon emitters (103Pd and 125I) present a very small uniform random component. The ratio of frequencies of clusters with respect to 60Co differs up to 15% for the lower energy sources and less than 2% for the higher energy sources when the maximum distance between each pair of EDs is 2 nm. At distances relevant to DNA damage, cluster patterns can be differentiated between the lower and higher energy sources. This may be part of the explanation to the reported difference in RBE values with initial DSB yields as an endpoint for these brachytherapy sources.

Cluster pattern analysis of energy deposition sites for the brachytherapy sources 103Pd, 125I, 192Ir, 137Cs, and 60Co

NASA Astrophysics Data System (ADS)

Villegas, Fernanda; Tilly, Nina; Bäckström, Gloria; Ahnesjö, Anders

2014-09-01

Analysing the pattern of energy depositions may help elucidate differences in the severity of radiation-induced DNA strand breakage for different radiation qualities. It is often claimed that energy deposition (ED) sites from photon radiation form a uniform random pattern, but there is indication of differences in RBE values among different photon sources used in brachytherapy. The aim of this work is to analyse the spatial patterns of EDs from 103Pd, 125I, 192Ir, 137Cs sources commonly used in brachytherapy and a 60Co source as a reference radiation. The results suggest that there is both a non-uniform and a uniform random component to the frequency distribution of distances to the nearest neighbour ED. The closest neighbouring EDs show high spatial correlation for all investigated radiation qualities, whilst the uniform random component dominates for neighbours with longer distances for the three higher mean photon energy sources (192Ir, 137Cs, and 60Co). The two lower energy photon emitters (103Pd and 125I) present a very small uniform random component. The ratio of frequencies of clusters with respect to 60Co differs up to 15% for the lower energy sources and less than 2% for the higher energy sources when the maximum distance between each pair of EDs is 2 nm. At distances relevant to DNA damage, cluster patterns can be differentiated between the lower and higher energy sources. This may be part of the explanation to the reported difference in RBE values with initial DSB yields as an endpoint for these brachytherapy sources.

Real-time photoacoustic imaging of prostate brachytherapy seeds using a clinical ultrasound system.

PubMed

Kuo, Nathanael; Kang, Hyun Jae; Song, Danny Y; Kang, Jin U; Boctor, Emad M

2012-06-01

Prostate brachytherapy is a popular prostate cancer treatment option that involves the permanent implantation of radioactive seeds into the prostate. However, contemporary brachytherapy procedure is limited by the lack of an imaging system that can provide real-time seed-position feedback. While many other imaging systems have been proposed, photoacoustic imaging has emerged as a potential ideal modality to address this need, since it could easily be incorporated into the current ultrasound system used in the operating room. We present such a photoacoustic imaging system built around a clinical ultrasound system to achieve the task of visualizing and localizing seeds. We performed several experiments to analyze the effects of various parameters on the appearance of brachytherapy seeds in photoacoustic images. We also imaged multiple seeds in an ex vivo dog prostate phantom to demonstrate the possibility of using this system in a clinical setting. Although still in its infancy, these initial results of a photoacoustic imaging system for the application of prostate brachytherapy seed localization are highly promising.

A Prospective Quasi-Randomized Comparison of Intraoperatively Built Custom-Linked Seeds Versus Loose Seeds for Prostate Brachytherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ishiyama, Hiromichi, E-mail: hishiyam@kitasato-u.ac.jp; Satoh, Takefumi; Kawakami, Shogo

Purpose: To compare dosimetric parameters, seed migration rates, operation times, and acute toxicities of intraoperatively built custom-linked (IBCL) seeds with those of loose seeds for prostate brachytherapy. Methods and Materials: Participants were 140 patients with low or intermediate prostate cancer prospectively allocated to an IBCL seed group (n=74) or a loose seed group (n=66), using quasirandomization (allocated by week of the month). All patients underwent prostate brachytherapy using an interactive plan technique. Computed tomography and plain radiography were performed the next day and 1 month after brachytherapy. The primary endpoint was detection of a 5% difference in dose to 90% ofmore » prostate volume on postimplant computed tomography 1 month after treatment. Seed migration was defined as a seed position >1 cm from the cluster of other seeds on radiography. A seed dropped into the seminal vesicle was also defined as a migrated seed. Results: Dosimetric parameters including the primary endpoint did not differ significantly between groups, but seed migration rate was significantly lower in the IBCL seed group (0%) than in the loose seed group (55%; P<.001). Mean operation time was slightly but significantly longer in the IBCL seed group (57 min) than in the loose seed group (50 min; P<.001). No significant differences in acute toxicities were seen between groups (median follow-up, 9 months). Conclusions: This prospective quasirandomized control trial showed no dosimetric differences between IBCL seed and loose seed groups. However, a strong trend toward decreased postimplant seed migration was shown in the IBCL seed group.« less

Study of two different radioactive sources for prostate brachytherapy treatment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pereira Neves, Lucio; Perini, Ana Paula; Souza Santos, William de

In this study we evaluated two radioactive sources for brachytherapy treatments. Our main goal was to quantify the absorbed doses on organs and tissues of an adult male patient, submitted to a brachytherapy treatment with two radioactive sources. We evaluated a {sup 192}Ir and a {sup 125}I radioactive sources. The {sup 192}Ir radioactive source is a cylinder with 0.09 cm in diameter and 0.415 cm long. The {sup 125}I radioactive source is also a cylinder, with 0.08 cm in diameter and 0.45 cm long. To evaluate the absorbed dose distribution on the prostate, and other organs and tissues of anmore » adult man, a male virtual anthropomorphic phantom MASH, coupled in the radiation transport code MCNPX 2.7.0, was employed.We simulated 75, 90 and 102 radioactive sources of {sup 125}I and one of {sup 192}Ir, inside the prostate, as normally used in these treatments, and each treatment was simulated separately. As this phantom was developed in a supine position, the displacement of the internal organs of the chest, compression of the lungs and reduction of the sagittal diameter were all taken into account. For the {sup 192}Ir, the higher doses values were obtained for the prostate and surrounding organs, as the colon, gonads and bladder. Considering the {sup 125}I sources, with photons with lower energies, the doses to organs that are far from the prostate were lower. All values for the dose rates are in agreement with those recommended for brachytherapy treatments. Besides that, the new seeds evaluated in this work present usefulness as a new tool in prostate brachytherapy treatments, and the methodology employed in this work may be applied for other radiation sources, or treatments. (authors)« less

Highly efficient method for production of radioactive silver seed cores for brachytherapy.

PubMed

Cardoso, Roberta Mansini; de Souza, Carla Daruich; Rostelato, Maria Elisa Chuery Martins; Araki, Koiti

2017-02-01

A simple and highly efficient (shorter reaction time and almost no rework) method for production of iodine based radioactive silver seed cores for brachytherapy is described. The method allows almost quantitative deposition of iodine-131 on dozens of silver substrates at once, with even distribution of activity per core and insignificant amounts of liquid and solid radioactive wastes, allowing the fabrication of cheaper radioactive iodine seeds for brachytherapy. Copyright © 2016. Published by Elsevier Ltd.

Evaluation of material heterogeneity dosimetric effects using radiochromic film for COMS eye plaques loaded with {sup 125}I seeds (model I25.S16)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Acar, Hilal; Chiu-Tsao, Sou-Tung; Oezbay, Ismail

Purpose: (1) To measure absolute dose distributions in eye phantom for COMS eye plaques with {sup 125}I seeds (model I25.S16) using radiochromic EBT film dosimetry. (2) To determine the dose correction function for calculations involving the TG-43 formalism to account for the presence of the COMS eye plaque using Monte Carlo (MC) method specific to this seed model. (3) To test the heterogeneous dose calculation accuracy of the new version of Plaque Simulator (v5.3.9) against the EBT film data for this seed model. Methods: Using EBT film, absolute doses were measured for {sup 125}I seeds (model I25.S16) in COMS eyemore » plaques (1) along the plaque's central axis for (a) uniformly loaded plaques (14-20 mm in diameter) and (b) a 20 mm plaque with single seed, and (2) in off-axis direction at depths of 5 and 12 mm for all four plaque sizes. The EBT film calibration was performed at {sup 125}I photon energy. MC calculations using MCNP5 code for a single seed at the center of a 20 mm plaque in homogeneous water and polystyrene medium were performed. The heterogeneity dose correction function was determined from the MC calculations. These function values at various depths were entered into PS software (v5.3.9) to calculate the heterogeneous dose distributions for the uniformly loaded plaques (of all four sizes). The dose distributions with homogeneous water assumptions were also calculated using PS for comparison. The EBT film measured absolute dose rate values (film) were compared with those calculated using PS with homogeneous assumption (PS Homo) and heterogeneity correction (PS Hetero). The values of dose ratio (film/PS Homo) and (film/PS Hetero) were obtained. Results: The central axis depth dose rate values for a single seed in 20 mm plaque measured using EBT film and calculated with MCNP5 code (both in ploystyrene phantom) were compared, and agreement within 9% was found. The dose ratio (film/PS Homo) values were substantially lower than unity (mostly between 0

A Novel Self-Expandable, Radioactive Airway Stent Loaded with 125I Seeds: A Feasibility and Safety Study in Healthy Beagle Dog.

PubMed

Wang, Yong; Guo, Jin-He; Zhu, Guang-Yu; Zhu, Hai-Dong; Chen, Li; Lu, Jian; Wang, Chao; Teng, Gao-Jun

2017-07-01

Airway stent placement is an effective treatment for the immediate palliation of malignant airway obstruction. However, restenosis caused by tumor ingrowth and/or overgrowth after stenting is common. The purpose of this study was to investigate the feasibility and safety of a novel self-expandable stent loaded with 125 I seeds in healthy beagle dog. Under fluoroscopic guidance, forty-eight self-expandable airway stents loaded with 125 I seeds were perorally placed in the main trachea of 48 healthy beagle dogs, who were randomly divided into four groups (Group A: 0.3 mCi; Group B: 0.6 mCi; Group C: 0.9 mCi; Control group: 0 mCi). The estimated radiation dose was calculated using the isotropic point source approximation. Radiological follow-up examinations and histopathological examinations of stented tracheal segments and their adjacent organs and tissues were performed at 2, 4, 8, and 16 weeks following the stenting. All stents were successfully deployed in the targeted tracheal segment in the beagle dogs without procedure-related complications. Tracheal stenosis became severe gradually in all the four groups, which was not associated with the radioactivity of 125 I seeds (p > 0.05). The tracheal injury scores increased along with the higher dose of radioactive seeds which reached peak at 8 weeks and then turned back slightly at 16 weeks. The adjacent tissue did not show pathohistological changes under microscope, while mild and reversible ultrastructure changes were showed under electronic microscope. This study demonstrates that it is feasible and safe to insert this novel self-expandable airway stent loaded with 125 I seeds in healthy beagle dog.

Sci-Thur PM – Brachytherapy 03: Identifying the impact of seroma visualization on permanent breast seed implant brachytherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morton, Daniel; Batchelar, Deidre; Hilts, Michelle

Purpose: Uncertainties in target identification can reduce treatment accuracy in permanent breast seed implant (PBSI) brachytherapy. This study evaluates the relationship between seroma visualization and seed placement accuracy. Methods: Spatially co-registered CT and 3D ultrasound (US) images were acquired for 10 patients receiving PBSI. Seromas were retrospectively contoured independently by 3 radiation oncologists on both CT and US and respective consensus volumes were defined, CTV{sub CT} and CTV{sub US}. The seroma clarity and inter-user conformity index (CI), as well as inter-modality CI, volume, and positional differences were evaluated. Correlations with seed placement accuracy were then assessed. CTVs were expanded bymore » 1.25cm to create PTV{sub CT} and PTV{sub US} and evaluate the conformity with PTV{sub Clinical} (CTV{sub Clinical}+1.25cm) used in treatment planning. The change in PTV coincidence by expanding PTV{sub Clinical} by 0.25cm was determined. Results: CTV{sub US} were a mean 68 ± 12% smaller than CTV{sub CT} and generally had improved clarity and inter-user conformity. No correlations between seed displacement and CTV{sub US}-CTV{sub CT} positional difference or CI were observed. Greater seed displacements were associated with larger CTV{sub US}-CTV{sub CT} volume differences (r=−0.65) and inter-user CT CI (r=−0.74). A median (range) 88% (71–99%) of PTV{sub CT} and 83% (69–100%) of PTV{sub US} were contained within PTV{sub Clinical}. Expanding treatment margins to 1.5cm increased coincidence to 98% (86–100%) and 94% (82–100%), respectively. Conclusions: Differences in seroma visualization impacts seed displacement in PBSI. Reducing dependence on CT by incorporating 3DUS into target identification, or expanding CT-based treatment margins to 1.5cm may reduce or mitigate uncertainties related to seroma visualization.« less

Modified COMS Plaques for {sup 125}I and {sup 103}Pd Iris Melanoma Brachytherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thomson, Rowan M., E-mail: rthomson@physics.carleton.c; Furutani, Keith M.; Pulido, Jose S.

2010-11-15

Purpose: Novel plaques are used to treat iris melanoma at the Mayo Clinic Rochester. The plaques are a modification of the Collaborative Ocular Melanoma Study (COMS) 22 mm plaque design with a gold alloy backing, outer lip, and silicone polymer insert. An inner lip surrounds a 10 mm diameter cutout region at the plaque center. Plaques span 360{sup o}, 270{sup o}, and 180{sup o} arcs. This article describes dosimetry for these plaques and others used in the treatment of anterior eye melanomas. Methods and Materials: The EGSnrc user-code BrachyDose is used to perform Monte Carlo simulations. Plaques and seeds aremore » fully modeled. Three-dimensional dose distributions for different plaque models, TG-43 calculations, and {sup 125}I (model 6711) and {sup 103}Pd (model 200) seeds are compared via depth-dose curves, tabulation of doses at points of interest, and isodose contours. Results: Doses at points of interest differ by up to 70% from TG-43 calculations. The inner lip reduces corneal doses. Matching plaque arc length to tumor extent reduces doses to eye regions outside the treatment area. Maintaining the same prescription dose, {sup 103}Pd offers lower doses to critical structures than {sup 125}I, with the exception of the sclera adjacent to the plaque. Conclusion: The Mayo Clinic plaques offer several advantages for anterior eye tumor treatments. Doses to regions outside the treatment area are significantly reduced. Doses differ considerably from TG-43 predictions, illustrating the importance of complete Monte Carlo simulations. Calculations take a few minutes on a single CPU, making BrachyDose sufficiently fast for routine clinical treatment planning.« less

Urethral toxicity after LDR brachytherapy: experience in Japan.

PubMed

Tanaka, Nobumichi; Asakawa, Isao; Hasegawa, Masatoshi; Fujimoto, Kiyohide

2015-01-01

Urinary toxicity is common after low-dose-rate (LDR) brachytherapy, and the resolution of urinary toxicity is a concern. In particular, urinary frequency is the most common adverse event among the urinary toxicities. We have previously reported that approximately 70% of patients experience urinary frequency during the first 6 months after seed implantation. Most urinary adverse events were classified as Grade 1, and Grade 2 or higher adverse events were rare. The incidence of urinary retention was approximately 2-4%. A high International Prostate Symptom Score before seed implantation was an independent predictor of acute urinary toxicity of Grade 2 or higher. Several previous reports from the United States also supported this trend. In Japan, LDR brachytherapy was legally approved in 2003. A nationwide prospective cohort study entitled Japanese Prostate Cancer Outcome Study of Permanent Iodine-125 Seed Implantation was initiated in July 2005. It is an important issue to limit urinary toxicities in patients who undergo LDR brachytherapy. Copyright © 2015 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

SU-E-T-378: Evaluation of An Analytical Model for the Inter-Seed Attenuation Effect in 103-Pd Multi-Seed Implant Brachytherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Safigholi, H; Soliman, A; Song, W

Purpose: Brachytherapy treatment planning systems based on TG-43 protocol calculate the dose in water and neglects the heterogeneity effect of seeds in multi-seed implant brachytherapy. In this research, the accuracy of a novel analytical model that we propose for the inter-seed attenuation effect (ISA) for 103-Pd seed model is evaluated. Methods: In the analytical model, dose perturbation due to the ISA effect for each seed in an LDR multi-seed implant for 103-Pd is calculated by assuming that the seed of interest is active and the other surrounding seeds are inactive. The cumulative dosimetric effect of all seeds is then summedmore » using the superposition principle. The model is based on pre Monte Carlo (MC) simulated 3D kernels of the dose perturbations caused by the ISA effect. The cumulative ISA effect due to multiple surrounding seeds is obtained by a simple multiplication of the individual ISA effect by each seed, the effect of which is determined by the distance from the seed of interest. This novel algorithm is then compared with full MC water-based simulations (FMCW). Results: The results show that the dose perturbation model we propose is in excellent agreement with the FMCW values for a case with three seeds separated by 1 cm. The average difference of the model and the FMCW simulations was less than 8%±2%. Conclusion: Using the proposed novel analytical ISA effect model, one could expedite the corrections due to the ISA dose perturbation effects during permanent seed 103-Pd brachytherapy planning with minimal increase in time since the model is based on multiplications and superposition. This model can be applied, in principle, to any other brachytherapy seeds. Further work is necessary to validate this model on a more complicated geometry as well.« less

Monte Carlo calculated doses to treatment volumes and organs at risk for permanent implant lung brachytherapy

NASA Astrophysics Data System (ADS)

Sutherland, J. G. H.; Furutani, K. M.; Thomson, R. M.

2013-10-01

Iodine-125 (125I) and Caesium-131 (131Cs) brachytherapy have been used with sublobar resection to treat stage I non-small cell lung cancer and other radionuclides, 169Yb and 103Pd, are considered for these treatments. This work investigates the dosimetry of permanent implant lung brachytherapy for a range of source energies and various implant sites in the lung. Monte Carlo calculated doses are calculated in a patient CT-derived computational phantom using the EGsnrc user-code BrachyDose. Calculations are performed for 103Pd, 125I, 131Cs seeds and 50 and 100 keV point sources for 17 implant positions. Doses to treatment volumes, ipsilateral lung, aorta, and heart are determined and compared to those determined using the TG-43 approach. Considerable variation with source energy and differences between model-based and TG-43 doses are found for both treatment volumes and organs. Doses to the heart and aorta generally increase with increasing source energy. TG-43 underestimates the dose to the heart and aorta for all implants except those nearest to these organs where the dose is overestimated. Results suggest that model-based dose calculations are crucial for selecting prescription doses, comparing clinical endpoints, and studying radiobiological effects for permanent implant lung brachytherapy.

SU-E-T-259: Particle Swarm Optimization in Radial Dose Function Fitting for a Novel Iodine-125 Seed

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, X; Duan, J; Popple, R

2014-06-01

Purpose: To determine the coefficients of bi- and tri-exponential functions for the best fit of radial dose functions of the new iodine brachytherapy source: Iodine-125 Seed AgX-100. Methods: The particle swarm optimization (PSO) method was used to search for the coefficients of the biand tri-exponential functions that yield the best fit to data published for a few selected radial distances from the source. The coefficients were encoded into particles, and these particles move through the search space by following their local and global best-known positions. In each generation, particles were evaluated through their fitness function and their positions were changedmore » through their velocities. This procedure was repeated until the convergence criterion was met or the maximum generation was reached. All best particles were found in less than 1,500 generations. Results: For the I-125 seed AgX-100 considered as a point source, the maximum deviation from the published data is less than 2.9% for bi-exponential fitting function and 0.2% for tri-exponential fitting function. For its line source, the maximum deviation is less than 1.1% for bi-exponential fitting function and 0.08% for tri-exponential fitting function. Conclusion: PSO is a powerful method in searching coefficients for bi-exponential and tri-exponential fitting functions. The bi- and tri-exponential models of Iodine-125 seed AgX-100 point and line sources obtained with PSO optimization provide accurate analytical forms of the radial dose function. The tri-exponential fitting function is more accurate than the bi-exponential function.« less

Clinical investigations on the spinal osteoblastic metastasis treated by combination of percutaneous vertebroplasty and (125)I seeds implantation versus radiotherapy.

PubMed

Yang, Zuozhang; Tan, Jing; Zhao, Ruilian; Wang, Jiaping; Sun, Hongpu; Wang, Xiaoxue; Xu, Lei; Jiang, Hua; Zhang, Jinlei

2013-02-01

To investigate the clinical efficacy of combining digital subtraction angiography-guided percutaneous vertebroplasty (PVP) and (125)I seeds implantation for the treatment of spinal osteoplastic metastasis. A combination of PVP and (125)I implantation was conducted for 50 patients with spinal osteoplastic metastasis, while the other 50 patients who received regular radiation therapy were used as a comparison. Visual analogue pain scale (VAS) and score of life quality (EORTCQLQ-30) were determined for all the patients. Surgery was successful in 89 spinal segments of vertebral body in 50 patients. Each segment of vertebral body was injected with 1-5 mL (2.8 mL for thoracic and 3.1 mL for lumbar vertebral body on average) of bone cement. Postoperative X-ray and CT examination showed that all the patients in the PVP group achieved spinal stability. During the follow-up examination from 6 months to 5 years, 49 patients (98.0%) had significantly relieved back pain, and only 1 case (2.0%) had no obvious improvement. Postoperative VAS score and Karnofsky performance score (KPS) were significantly different from the preoperative scores (p<0.05); and compared to the regular treatment group, PVP combined (125)I seeds showed much better clinical efficacy (p<0.05). PVP is a minimally invasive treatment with easy operation and less complications. PVP can effectively relieve the pain, stabilize the spine, improve the life quality, and reduce the occurrence of paraplegia in patients with spinal osteoplastic metastasis. Utilization of (125)I seeds with PVP can enhance the clinical efficacy.

Implantable chemothermal brachytherapy seeds: A synergistic approach to brachytherapy using polymeric dual drug delivery and hyperthermia for malignant solid tumor ablation.

PubMed

Aguilar, Ludwig Erik; Thomas, Reju George; Moon, Myeong Ju; Jeong, Yong Yeon; Park, Chan Hee; Kim, Cheol Sang

2018-08-01

Chemothermal brachytherapy seeds have been developed using a combination of polymeric dual drug chemotherapy and alternating magnetic field induced hyperthermia. The synergistic effect of chemotherapy and hyperthermia brachytherapy has been investigated in a way that has never been performed before, with an in-depth analysis of the cancer cell inhibition property of the new system. A comprehensive in vivo study on athymic mice model with SCC7 tumor has been conducted to determine optimal arrays and specifications of the chemothermal seeds. Dual drug chemotherapy has been achieved via surface deposition of polydopamine that carries bortezomib, and also via loading an acidic pH soluble hydrogel that contains 5-Fluorouracil inside the chemothermal seed; this increases the drug loading capacity of the chemothermal seed, and creates dual drug synergism. An external alternating magnetic field has been utilized to induce hyperthermia conditions, using the inherent ferromagnetic property of the nitinol alloy used as the seed casing. The materials used in this study were fully characterized using FESEM, H 1 NMR, FT-IR, and XPS to validate their properties. This new approach to experimental cancer treatment is a pilot study that exhibits the potential of thermal brachytherapy and chemotherapy as a combined treatment modality. Copyright © 2018 Elsevier B.V. All rights reserved.

Sci-Sat AM(2): Brachy-07: Tomosynthesis-based seed reconstruction in LDR prostate brachytherapy: A clinical study.

PubMed

Brunet-Benkhoucha, M; Verhaegen, F; Lassalle, S; Béliveau-Nadeau, D; Reniers, B; Donath, D; Taussky, D; Carrier, J-F

2008-07-01

To develop a tomosynthesis-based dose assessment procedure that can be performed after an I-125 prostate seed implantation, while the patient is still under anaesthesia on the treatment table. Our seed detection procedure involves the reconstruction of a volume of interest based on the backprojection of 7 seed-only binary images acquired over an angle of 60° with an isocentric imaging system. A binary seed-only volume is generated by a simple thresholding of the volume of interest. Seeds positions are extracted from this volume with a 3D connected component analysis and a statistical classifier that determines the number of seeds in each cluster of connected voxels. A graphical user interface (GUI) allows to visualize the result and to introduce corrections, if needed. A phantom and a clinical study (24 patients) were carried out to validate the technique. A phantom study demonstrated a very good localization accuracy of (0.4+/-0.4) mm when compared to CT-based reconstruction. This leads to dosimetric error on D90 and V100 of respectively 0.5% and 0.1%. In a patient study with an average of 56 seeds per implant, the automatic tomosynthesis-based reconstruction yields a detection rate of 96% of the seeds and less than 1.5% of false-positives. With the help of the GUI, the user can achieve a 100% detection rate in an average of 3 minutes. This technique would allow to identify possible underdosage and to correct it by potentially reimplanting additional seeds. A more uniform dose coverage could then be achieved in LDR prostate brachytherapy. © 2008 American Association of Physicists in Medicine.

Enhanced Ultrasound Visualization of Brachytherapy Seeds by a Novel Magnetically Induced Motion Imaging Method

DTIC Science & Technology

2007-04-01

We report our progress in developing Magnetically Induced Motion Imaging (MIMI) for unambiguous identification and localization brachytherapy seeds ...tail artifacts in segmented seed images. The second is a method for joining ends of seeds in segmented seed images based on the phase of the detected

SU-F-T-43: Prediction of Dose Increments by Brain Metastases Resection Cavity Shrinkage Model with I-125 and Cs-131 LDR Seed Implantations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, D; Braunstein, S; Sneed, P

Purpose: This work aims to determine dose variability via a brain metastases resection cavity shrinkage model (RC-SM) with I-125 or Cs-131 LDR seed implantations. Methods: The RC-SM was developed to represent sequential volume changes of 95 consecutive brain metastases patients. All patients underwent serial surveillance MR and change in cavity volume was recorded for each patient. For the initial resection cavity, a prolate-ellipsoid cavity model was suggested and applied volume shrinkage rates to correspond to 1.7, 3.6, 5.9, 11.7, and 20.5 months after craniotomy. Extra-ring structure (6mm) was added on a surface of the resection volume and the same shrinkagemore » rates were applied. Total 31 LDR seeds were evenly distributed on the surface of the resection cavity. The Amersham 6711 I-125 seed model (Oncura, Arlington Heights, IL) and the Model Cs-1 Rev2 Cs-131 seed model (IsoRay, Richland, WA) were used for TG-43U1 dose calculation and in-house-programed 3D-volumetric dose calculation system was used for resection cavity rigid model (RC-RM) and the RC-SM dose calculation. Results: The initial resection cavity volume shrunk to 25±6%, 35±6.8%, 42±7.7%, 47±9.5%, and 60±11.6%, with respect to sequential MR images post craniotomy, and the shrinkage rate (SR) was calculated as SR=56.41Xexp(−0.2024Xt)+33.99 and R-square value was 0.98. The normal brain dose as assessed via the dose to the ring structure with the RC-SM showed 29.34% and 27.95% higher than the RC-RM, I-125 and Cs-131, respectively. The dose differences between I-125 and Cs-131 seeds within the same models, I-125 cases were 9.17% and 10.35% higher than Cs-131 cases, the RC-RM and the RC-SM, respectively. Conclusion: A realistic RC-SM should be considered during LDR brain seed implementation and post-implement planning to prevent potential overdose. The RC-SM calculation shows that Cs-131 is more advantageous in sparing normal brain as the resection cavity volume changes with the LDR seeds

/sup 125/I interstitial implants in the RIF-1 murine flank tumor: an animal model for brachytherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bernstein, M.; Gutin, P.H.; Weaver, D.A.

1982-09-01

The development of a model for interstitial brachytherapy that uses high-activity, removable /sup 125/I sources in the RIF-1 murine flank tumor is reported. Experimental end points are clonogenic cell and tumor regrowth delay assays. For the clonogenic cell assay, interestitial radiation is delivered at total doses of 500-10,000 rad at dose rates of 0.9-2.7 rad/min to cells in annuli of tissue in the tumor. Dose-survival curves are characterized by an initial shoulder followed by a straight (exponential) portion, with D/sub 0/ similar to that of the curve obtained by external irradiation of the RIF-1 tumor in a self-contained cesium irradiatormore » at similar dose rates. Tumor regrowth curves have been obtained for minimum tumor doses of 500-5000 rad; marked tumor regression has been observed with minimum tumor doses as low as 2000 rad, but results are not as reproducible as the results obtained with the clonogenic cell assay.« less

Iodine-125 Seeds Strand for Treatment of Tumor Thrombus in Inferior Vena Cava: An Experimental Study in a Rabbit Model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Wen, E-mail: wenzhangxiao@126.com; Yan, Zhiping, E-mail: Yan.zhiping@zs-hospital.sh.cn; Luo, Jianjun, E-mail: luo.jianjun@zs-hospital.sh.cn

Objective: The purpose of this study was to establish an animal model of implanted inferior vena cava tumor thrombus (IVCTT) and to evaluate the effect of linear iodine-125 seeds strand in treating implanted IVCTT. Methods: Tumor cell line VX{sub 2} was inoculated subcutaneously into New Zealand rabbit to develop the parent tumor. The tumor strip was inoculated into inferior vena cava (IVC) to establish the IVCTT model. The IVCTT was confirmed by multidetector computed tomography (MDCT) after 2 weeks. Twelve rabbits with IVCTT were randomly divided into two groups. Treatment group (group T; n = 6) underwent Iodine-125 seeds brachytherapy,more » and the control group (group C; n = 6) underwent blank seeds strand. The blood laboratory examination (including blood routine examination, hepatic and renal function), body weight, survival time, and IVCTT volume by MDCT were monitored. All rabbits were dissected postmortem, and the therapeutic effects were evaluated on the basis of histopathology. The proliferating cell nuclear antigen index (PI) and apoptosis index (AI) of IVCTT were compared between two groups. T test, Wilcoxon rank test, and Kaplan-Meier survival curve analysis were used. Results: The success rate of establishing IVCTT was 100 %. The body weight loss and cachexia of rabbits in group C appeared earlier than in group T. Body weight in the third week, the mean survival time, PI, AI in groups T and C were 2.23 {+-} 0.12 kg, 57.83 {+-} 8.68 days, (16.73 {+-} 5.18 %), (29.47 {+-} 7.18 %), and 2.03 {+-} 0.13 kg, 43.67 {+-} 5.28 days, (63.01 {+-} 2.01 %), (6.02 {+-} 2.93 %), respectively. There were statistically significant differences between group T and group C (P < 0.05). The IVCTT volume of group T was remarkably smaller than that of group C. Conclusions: Injecting and suspensory fixing VX2 tumor strip into IVC is a reliable method to establish IVCTT animal model. The linear Iodine-125 seeds strand brachytherapy was a safe and effective method for

In vitro Dosimetric Study of Biliary Stent Loaded with Radioactive 125I Seeds

PubMed Central

Yao, Li-Hong; Wang, Jun-Jie; Shang, Charles; Jiang, Ping; Lin, Lei; Sun, Hai-Tao; Liu, Lu; Liu, Hao; He, Di; Yang, Rui-Jie

2017-01-01

Background: A novel radioactive 125I seed-loaded biliary stent has been used for patients with malignant biliary obstruction. However, the dosimetric characteristics of the stents remain unclear. Therefore, we aimed to describe the dosimetry of the stents of different lengths — with different number as well as activities of 125I seeds. Methods: The radiation dosimetry of three representative radioactive stent models was evaluated using a treatment planning system (TPS), thermoluminescent dosimeter (TLD) measurements, and Monte Carlo (MC) simulations. In the process of TPS calculation and TLD measurement, two different water-equivalent phantoms were designed to obtain cumulative radial dose distribution. Calibration procedures using TLD in the designed phantom were also conducted. MC simulations were performed using the Monte Carlo N-Particle eXtended version 2.5 general purpose code to calculate the radioactive stent's three-dimensional dose rate distribution in liquid water. Analysis of covariance was used to examine the factors influencing radial dose distribution of the radioactive stent. Results: The maximum reduction in cumulative radial dose was 26% when the seed activity changed from 0.5 mCi to 0.4 mCi for the same length of radioactive stents. The TLD's dose response in the range of 0–10 mGy irradiation by 137Cs γ-ray was linear: y = 182225x − 6651.9 (R2= 0.99152; y is the irradiation dose in mGy, x is the TLDs’ reading in nC). When TLDs were irradiated by different energy radiation sources to a dose of 1 mGy, reading of TLDs was different. Doses at a distance of 0.1 cm from the three stents’ surface simulated by MC were 79, 93, and 97 Gy. Conclusions: TPS calculation, TLD measurement, and MC simulation were performed and were found to be in good agreement. Although the whole experiment was conducted in water-equivalent phantom, data in our evaluation may provide a theoretical basis for dosimetry for the clinical application. PMID:28469106

Plastic optical fibre sensor for in-vivo radiation monitoring during brachytherapy

NASA Astrophysics Data System (ADS)

Woulfe, P.; Sullivan, F. J.; Lewis, E.; O'Keeffe, S.

2015-09-01

An optical fibre sensor is presented for applications in real-time in-vivo monitoring of the radiation dose a cancer patient receives during seed implantation in Brachytherapy. The sensor is based on radioluminescence whereby radiation sensitive scintillation material is embedded in the core of a 1mm plastic optical fibre. Three scintillation materials are investigated: thallium-doped caesium iodide (CsI:Tl), terbium-doped gadolinium oxysulphide (Gd2O2S:Tb) and europium-doped lanthanum oxysulphide (La2O2S:Eu). Terbium-doped gadolinium oxysulphide was identified as being the most suitable scintillator and further testing demonstrates its measureable response to different activities of Iodine-125, the radio-active source commonly used in Brachytherapy for treating prostate cancer.

Detection and correction of patient movement in prostate brachytherapy seed reconstruction

NASA Astrophysics Data System (ADS)

Lam, Steve T.; Cho, Paul S.; Marks, Robert J., II; Narayanan, Sreeram

2005-05-01

Intraoperative dosimetry of prostate brachytherapy can help optimize the dose distribution and potentially improve clinical outcome. Evaluation of dose distribution during the seed implant procedure requires the knowledge of 3D seed coordinates. Fluoroscopy-based seed localization is a viable option. From three x-ray projections obtained at different gantry angles, 3D seed positions can be determined. However, when local anaesthesia is used for prostate brachytherapy, the patient movement during fluoroscopy image capture becomes a practical problem. If uncorrected, the errors introduced by patient motion between image captures would cause seed mismatches. Subsequently, the seed reconstruction algorithm would either fail to reconstruct or yield erroneous results. We have developed an algorithm that permits detection and correction of patient movement that may occur between fluoroscopy image captures. The patient movement is decomposed into translational shifts along the tabletop and rotation about an axis perpendicular to the tabletop. The property of spatial invariance of the co-planar imaging geometry is used for lateral movement correction. Cranio-caudal movement is corrected by analysing the perspective invariance along the x-ray axis. Rotation is estimated by an iterative method. The method can detect and correct for the range of patient movement commonly seen in the clinical environment. The algorithm has been implemented for routine clinical use as the preprocessing step for seed reconstruction.

Conventional Versus Automated Implantation of Loose Seeds in Prostate Brachytherapy: Analysis of Dosimetric and Clinical Results

DOE Office of Scientific and Technical Information (OSTI.GOV)

Genebes, Caroline, E-mail: genebes.caroline@claudiusregaud.fr; Filleron, Thomas; Graff, Pierre

2013-11-15

Purpose: To review the clinical outcome of I-125 permanent prostate brachytherapy (PPB) for low-risk and intermediate-risk prostate cancer and to compare 2 techniques of loose-seed implantation. Methods and Materials: 574 consecutive patients underwent I-125 PPB for low-risk and intermediate-risk prostate cancer between 2000 and 2008. Two successive techniques were used: conventional implantation from 2000 to 2004 and automated implantation (Nucletron, FIRST system) from 2004 to 2008. Dosimetric and biochemical recurrence-free (bNED) survival results were reported and compared for the 2 techniques. Univariate and multivariate analysis researched independent predictors for bNED survival. Results: 419 (73%) and 155 (27%) patients with low-riskmore » and intermediate-risk disease, respectively, were treated (median follow-up time, 69.3 months). The 60-month bNED survival rates were 95.2% and 85.7%, respectively, for patients with low-risk and intermediate-risk disease (P=.04). In univariate analysis, patients treated with automated implantation had worse bNED survival rates than did those treated with conventional implantation (P<.0001). By day 30, patients treated with automated implantation showed lower values of dose delivered to 90% of prostate volume (D90) and volume of prostate receiving 100% of prescribed dose (V100). In multivariate analysis, implantation technique, Gleason score, and V100 on day 30 were independent predictors of recurrence-free status. Grade 3 urethritis and urinary incontinence were observed in 2.6% and 1.6% of the cohort, respectively, with no significant differences between the 2 techniques. No grade 3 proctitis was observed. Conclusion: Satisfactory 60-month bNED survival rates (93.1%) and acceptable toxicity (grade 3 urethritis <3%) were achieved by loose-seed implantation. Automated implantation was associated with worse dosimetric and bNED survival outcomes.« less

Vibro-acoustography with 1.75D ultrasound array transducer for detection and localization of permanent prostate brachytherapy seeds: ex vivo study

NASA Astrophysics Data System (ADS)

Mehrmohammadi, Mohammad; Alizad, Azra; Kinnick, Randall R.; Davis, Brian J.; Fatemi, Mostafa

2013-03-01

Effective brachytherapy procedures require precise placement of radioactive seeds in the prostate. Currently, transrectal ultrasound (TRUS) imaging is one of the main intraoperative imaging modalities to assist physicians in placement of brachytherapy seeds. However, the seed detection rate with TRUS is poor mainly because ultrasound imaging is highly sensitive to variations in seed orientation. The purpose of this study is to investigate the abilities of a new acoustic radiation force imaging modality, vibro-acoustography (VA), equipped with a 1.75D array transducer and implemented on a customized clinical ultrasound scanner, to image and localize brachytherapy seeds in prostatic tissue. To perform experiments, excised cadaver prostate specimens were implanted with dummy brachytherapy seeds, and embedded in tissue mimicking gel to simulate the properties of the surrounding soft tissues. The samples were scanned using the VA system and the resulting VA signals were used to reconstruct VA images at several depths inside the tissue. To further evaluate the performance of VA in detecting seeds, X-ray computed tomography (CT) images of the same tissue sample, were obtained and used as a gold-standard to compare the number of seeds detected by the two methods. Our results indicate that VA is capable of imaging of brachytherapy seeds with accuracy and high contrast, and can detect a large percentage of the seeds implanted within the tissue samples.

SU-G-201-02: Application of RayStretch in Clinical Cases: A Calculation for Heterogeneity Corrections in LDR Permanent I-125 Prostate Brachytherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hueso-Gonzalez, F; Vijande, J; Ballester, F

Purpose: Tissue heterogeneities and calcifications have significant impact on the dosimetry of low energy brachytherapy (BT). RayStretch is an analytical algorithm developed in our institution to incorporate heterogeneity corrections in LDR prostate brachytherapy. The aim of this work is to study its application in clinical cases by comparing its predictions with the results obtained with TG-43 and Monte Carlo (MC) simulations. Methods: A clinical implant (71 I-125 seeds, 15 needles) from a real patient was considered. On this patient, different volumes with calcifications were considered. Its properties were evaluated in three ways by i) the Treatment planning system (TPS) (TG-43),more » ii) a MC study using the Penelope2009 code, and iii) RayStretch. To analyse the performance of RayStretch, calcifications located in the prostate lobules covering 11% of the total prostate volume and larger calcifications located in the lobules and underneath the urethra for a total occupied volume of 30% were considered. Three mass densities (1.05, 1.20, and 1.35 g/cm3) were explored for the calcifications. Therefore, 6 different scenarios ranging from small low density calcifications to large high density ones have been discussed. Results: DVH and D90 results given by RayStretch agree within 1% with the full MC simulations. Although no effort has been done to improve RayStretch numerical performance, its present implementation is able to evaluate a clinical implant in a few seconds to the same level of accuracy as a detailed MC calculation. Conclusion: RayStretch is a robust method for heterogeneity corrections in prostate BT supported on TG-43 data. Its compatibility with commercial TPSs and its high calculation speed makes it feasible for use in clinical settings for improving treatment quality. It will allow in a second phase of this project, its use during intraoperative ultrasound planning. This study was partly supported by a fellowship grant from the Spanish Ministry of

SU-F-T-02: Estimation of Radiobiological Doses (BED and EQD2) of Single Fraction Electronic Brachytherapy That Equivalent to I-125 Eye Plaque: By Using Linear-Quadratic and Universal Survival Curve Models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Y; Waldron, T; Pennington, E

Purpose: To test the radiobiological impact of hypofractionated choroidal melanoma brachytherapy, we calculated single fraction equivalent doses (SFED) of the tumor that equivalent to 85 Gy of I125-BT for 20 patients. Corresponding organs-at-risks (OARs) doses were estimated. Methods: Twenty patients treated with I125-BT were retrospectively examined. The tumor SFED values were calculated from tumor BED using a conventional linear-quadratic (L-Q) model and an universal survival curve (USC). The opposite retina (α/β = 2.58), macula (2.58), optic disc (1.75), and lens (1.2) were examined. The % doses of OARs over tumor doses were assumed to be the same as for amore » single fraction delivery. The OAR SFED values were converted into BED and equivalent dose in 2 Gy fraction (EQD2) by using both L-Q and USC models, then compared to I125-BT. Results: The USC-based BED and EQD2 doses of the macula, optic disc, and the lens were on average 118 ± 46% (p < 0.0527), 126 ± 43% (p < 0.0354), and 112 ± 32% (p < 0.0265) higher than those of I125-BT, respectively. The BED and EQD2 doses of the opposite retina were 52 ± 9% lower than I125-BT. The tumor SFED values were 25.2 ± 3.3 Gy and 29.1 ± 2.5 Gy when using USC and LQ models which can be delivered within 1 hour. All BED and EQD2 values using L-Q model were significantly larger when compared to the USC model (p < 0.0274) due to its large single fraction size (> 14 Gy). Conclusion: The estimated single fraction doses were feasible to be delivered within 1 hour using a high dose rate source such as electronic brachytherapy (eBT). However, the estimated OAR doses using eBT were 112 ∼ 118% higher than when using the I125-BT technique. Continued exploration of alternative dose rate or fractionation schedules should be followed.« less

A radiobiology-based inverse treatment planning method for optimisation of permanent l-125 prostate implants in focal brachytherapy.

PubMed

Haworth, Annette; Mears, Christopher; Betts, John M; Reynolds, Hayley M; Tack, Guido; Leo, Kevin; Williams, Scott; Ebert, Martin A

2016-01-07

Treatment plans for ten patients, initially treated with a conventional approach to low dose-rate brachytherapy (LDR, 145 Gy to entire prostate), were compared with plans for the same patients created with an inverse-optimisation planning process utilising a biologically-based objective. The 'biological optimisation' considered a non-uniform distribution of tumour cell density through the prostate based on known and expected locations of the tumour. Using dose planning-objectives derived from our previous biological-model validation study, the volume of the urethra receiving 125% of the conventional prescription (145 Gy) was reduced from a median value of 64% to less than 8% whilst maintaining high values of TCP. On average, the number of planned seeds was reduced from 85 to less than 75. The robustness of plans to random seed displacements needs to be carefully considered when using contemporary seed placement techniques. We conclude that an inverse planning approach to LDR treatments, based on a biological objective, has the potential to maintain high rates of tumour control whilst minimising dose to healthy tissue. In future, the radiobiological model will be informed using multi-parametric MRI to provide a personalised medicine approach.

A radiobiology-based inverse treatment planning method for optimisation of permanent l-125 prostate implants in focal brachytherapy

NASA Astrophysics Data System (ADS)

Haworth, Annette; Mears, Christopher; Betts, John M.; Reynolds, Hayley M.; Tack, Guido; Leo, Kevin; Williams, Scott; Ebert, Martin A.

2016-01-01

Treatment plans for ten patients, initially treated with a conventional approach to low dose-rate brachytherapy (LDR, 145 Gy to entire prostate), were compared with plans for the same patients created with an inverse-optimisation planning process utilising a biologically-based objective. The ‘biological optimisation’ considered a non-uniform distribution of tumour cell density through the prostate based on known and expected locations of the tumour. Using dose planning-objectives derived from our previous biological-model validation study, the volume of the urethra receiving 125% of the conventional prescription (145 Gy) was reduced from a median value of 64% to less than 8% whilst maintaining high values of TCP. On average, the number of planned seeds was reduced from 85 to less than 75. The robustness of plans to random seed displacements needs to be carefully considered when using contemporary seed placement techniques. We conclude that an inverse planning approach to LDR treatments, based on a biological objective, has the potential to maintain high rates of tumour control whilst minimising dose to healthy tissue. In future, the radiobiological model will be informed using multi-parametric MRI to provide a personalised medicine approach.

In vivo dosimetry using a linear Mosfet-array dosimeter to determine the urethra dose in 125I permanent prostate implants.

PubMed

Bloemen-van Gurp, Esther J; Murrer, Lars H P; Haanstra, Björk K C; van Gils, Francis C J M; Dekker, Andre L A J; Mijnheer, Ben J; Lambin, Philippe

2009-01-01

In vivo dosimetry during brachytherapy of the prostate with (125)I seeds is challenging because of the high dose gradients and low photon energies involved. We present the results of a study using metal-oxide-semiconductor field-effect transistor (MOSFET) dosimeters to evaluate the dose in the urethra after a permanent prostate implantation procedure. Phantom measurements were made to validate the measurement technique, determine the measurement accuracy, and define action levels for clinical measurements. Patient measurements were performed with a MOSFET array in the urinary catheter immediately after the implantation procedure. A CT scan was performed, and dose values, calculated by the treatment planning system, were compared to in vivo dose values measured with MOSFET dosimeters. Corrections for temperature dependence of the MOSFET array response and photon attenuation in the catheter on the in vivo dose values are necessary. The overall uncertainty in the measurement procedure, determined in a simulation experiment, is 8.0% (1 SD). In vivo dose values were obtained for 17 patients. In the high-dose region (> 100 Gy), calculated and measured dose values agreed within 1.7% +/- 10.7% (1 SD). In the low-dose region outside the prostate (< 100 Gy), larger deviations occurred. MOSFET detectors are suitable for in vivo dosimetry during (125)I brachytherapy of prostate cancer. An action level of +/- 16% (2 SD) for detection of errors in the implantation procedure is achievable after validation of the detector system and measurement conditions.

WE-AB-BRA-11: Improved Imaging of Permanent Prostate Brachytherapy Seed Implants by Combining an Endorectal X-Ray Sensor with a CT Scanner

DOE Office of Scientific and Technical Information (OSTI.GOV)

Steiner, J; Matthews, K; Jia, G

Purpose: To test feasibility of the use of a digital endorectal x-ray sensor for improved image resolution of permanent brachytherapy seed implants compared to conventional CT. Methods: Two phantoms simulating the male pelvic region were used to test the capabilities of a digital endorectal x-ray sensor for imaging permanent brachytherapy seed implants. Phantom 1 was constructed from acrylic plastic with cavities milled in the locations of the prostate and the rectum. The prostate cavity was filled a Styrofoam plug implanted with 10 training seeds. Phantom 2 was constructed from tissue-equivalent gelatins and contained a prostate phantom implanted with 18 strandsmore » of training seeds. For both phantoms, an intraoral digital dental x-ray sensor was placed in the rectum within 2 cm of the seed implants. Scout scans were taken of the phantoms over a limited arc angle using a CT scanner (80 kV, 120–200 mA). The dental sensor was removed from the phantoms and normal helical CT and scout (0 degree) scans using typical parameters for pelvic CT (120 kV, auto-mA) were collected. A shift-and add tomosynthesis algorithm was developed to localize seed plane location normal to detector face. Results: The endorectal sensor produced images with improved resolution compared to CT scans. Seed clusters and individual seed geometry were more discernable using the endorectal sensor. Seed 3D locations, including seeds that were not located in every projection image, were discernable using the shift and add algorithm. Conclusion: This work shows that digital endorectal x-ray sensors are a feasible method for improving imaging of permanent brachytherapy seed implants. Future work will consist of optimizing the tomosynthesis technique to produce higher resolution, lower dose images of 1) permanent brachytherapy seed implants for post-implant dosimetry and 2) fine anatomic details for imaging and managing prostatic disease compared to CT images. Funding: LSU Faculty Start-up Funding

An NTCP Analysis of Urethral Complications from Low Doserate Mono- and Bi-Radionuclide Brachytherapy.

PubMed

Nuttens, V E; Nahum, A E; Lucas, S

2011-01-01

Urethral NTCP has been determined for three prostates implanted with seeds based on (125)I (145 Gy), (103)Pd (125 Gy), (131)Cs (115 Gy), (103)Pd-(125)I (145 Gy), or (103)Pd-(131)Cs (115 Gy or 130 Gy). First, DU(20), meaning that 20% of the urhral volume receive a dose of at least DU(20), is converted into an I-125 LDR equivalent DU(20) in order to use the urethral NTCP model. Second, the propagation of uncertainties through the steps in the NTCP calculation was assessed in order to identify the parameters responsible for large data uncertainties. Two sets of radiobiological parameters were studied. The NTCP results all fall in the 19%-23% range and are associated with large uncertainties, making the comparison difficult. Depending on the dataset chosen, the ranking of NTCP values among the six seed implants studied changes. Moreover, the large uncertainties on the fitting parameters of the urethral NTCP model result in large uncertainty on the NTCP value. In conclusion, the use of NTCP model for permanent brachytherapy is feasible but it is essential that the uncertainties on the parameters in the model be reduced.

Automatic seed picking for brachytherapy postimplant validation with 3D CT images.

PubMed

Zhang, Guobin; Sun, Qiyuan; Jiang, Shan; Yang, Zhiyong; Ma, Xiaodong; Jiang, Haisong

2017-11-01

Postimplant validation is an indispensable part in the brachytherapy technique. It provides the necessary feedback to ensure the quality of operation. The ability to pick implanted seed relates directly to the accuracy of validation. To address it, an automatic approach is proposed for picking implanted brachytherapy seeds in 3D CT images. In order to pick seed configuration (location and orientation) efficiently, the approach starts with the segmentation of seed from CT images using a thresholding filter which based on gray-level histogram. Through the process of filtering and denoising, the touching seed and single seed are classified. The true novelty of this approach is found in the application of the canny edge detection and improved concave points matching algorithm to separate touching seeds. Through the computation of image moments, the seed configuration can be determined efficiently. Finally, two different experiments are designed to verify the performance of the proposed approach: (1) physical phantom with 60 model seeds, and (2) patient data with 16 cases. Through assessment of validated results by a medical physicist, the proposed method exhibited promising results. Experiment on phantom demonstrates that the error of seed location and orientation is within ([Formula: see text]) mm and ([Formula: see text])[Formula: see text], respectively. In addition, the most seed location and orientation error is controlled within 0.8 mm and 3.5[Formula: see text] in all cases, respectively. The average process time of seed picking is 8.7 s per 100 seeds. In this paper, an automatic, efficient and robust approach, performed on CT images, is proposed to determine the implanted seed location as well as orientation in a 3D workspace. Through the experiments with phantom and patient data, this approach also successfully exhibits good performance.

GGEMS-Brachy: GPU GEant4-based Monte Carlo simulation for brachytherapy applications

NASA Astrophysics Data System (ADS)

Lemaréchal, Yannick; Bert, Julien; Falconnet, Claire; Després, Philippe; Valeri, Antoine; Schick, Ulrike; Pradier, Olivier; Garcia, Marie-Paule; Boussion, Nicolas; Visvikis, Dimitris

2015-07-01

In brachytherapy, plans are routinely calculated using the AAPM TG43 formalism which considers the patient as a simple water object. An accurate modeling of the physical processes considering patient heterogeneity using Monte Carlo simulation (MCS) methods is currently too time-consuming and computationally demanding to be routinely used. In this work we implemented and evaluated an accurate and fast MCS on Graphics Processing Units (GPU) for brachytherapy low dose rate (LDR) applications. A previously proposed Geant4 based MCS framework implemented on GPU (GGEMS) was extended to include a hybrid GPU navigator, allowing navigation within voxelized patient specific images and analytically modeled 125I seeds used in LDR brachytherapy. In addition, dose scoring based on track length estimator including uncertainty calculations was incorporated. The implemented GGEMS-brachy platform was validated using a comparison with Geant4 simulations and reference datasets. Finally, a comparative dosimetry study based on the current clinical standard (TG43) and the proposed platform was performed on twelve prostate cancer patients undergoing LDR brachytherapy. Considering patient 3D CT volumes of 400  × 250  × 65 voxels and an average of 58 implanted seeds, the mean patient dosimetry study run time for a 2% dose uncertainty was 9.35 s (≈500 ms 10-6 simulated particles) and 2.5 s when using one and four GPUs, respectively. The performance of the proposed GGEMS-brachy platform allows envisaging the use of Monte Carlo simulation based dosimetry studies in brachytherapy compatible with clinical practice. Although the proposed platform was evaluated for prostate cancer, it is equally applicable to other LDR brachytherapy clinical applications. Future extensions will allow its application in high dose rate brachytherapy applications.

Multivariable model development and internal validation for prostate cancer specific survival and overall survival after whole-gland salvage Iodine-125 prostate brachytherapy.

PubMed

Peters, Max; van der Voort van Zyp, Jochem R N; Moerland, Marinus A; Hoekstra, Carel J; van de Pol, Sandrine; Westendorp, Hendrik; Maenhout, Metha; Kattevilder, Rob; Verkooijen, Helena M; van Rossum, Peter S N; Ahmed, Hashim U; Shah, Taimur T; Emberton, Mark; van Vulpen, Marco

2016-04-01

Whole-gland salvage Iodine-125-brachytherapy is a potentially curative treatment strategy for localised prostate cancer (PCa) recurrences after radiotherapy. Prognostic factors influencing PCa-specific and overall survival (PCaSS & OS) are not known. The objective of this study was to develop a multivariable, internally validated prognostic model for survival after whole-gland salvage I-125-brachytherapy. Whole-gland salvage I-125-brachytherapy patients treated in the Netherlands from 1993-2010 were included. Eligible patients had a transrectal ultrasound-guided biopsy-confirmed localised recurrence after biochemical failure (clinical judgement, ASTRO or Phoenix-definition). Recurrences were assessed clinically and with CT and/or MRI. Metastases were excluded using CT/MRI and technetium-99m scintigraphy. Multivariable Cox-regression was used to assess the predictive value of clinical characteristics in relation to PCa-specific and overall mortality. PCa-specific mortality was defined as patients dying with distant metastases present. Missing data were handled using multiple imputation (20 imputed sets). Internal validation was performed and the C-statistic calculated. Calibration plots were created to visually assess the goodness-of-fit of the final model. Optimism-corrected survival proportions were calculated. All analyses were performed according to the TRIPOD statement. Median total follow-up was 78months (range 5-139). A total of 62 patients were treated, of which 28 (45%) died from PCa after mean (±SD) 82 (±36) months. Overall, 36 patients (58%) patients died after mean 84 (±40) months. PSA doubling time (PSADT) remained a predictive factor for both types of mortality (PCa-specific and overall): corrected hazard ratio's (HR's) 0.92 (95% CI: 0.86-0.98, p=0.02) and 0.94 (95% CI: 0.90-0.99, p=0.01), respectively (C-statistics 0.71 and 0.69, respectively). Calibration was accurate up to 96month follow-up. Over 80% of patients can survive 8years if PSADT>24

Dosimetric effects of seed anisotropy and interseed attenuation for {sup 103}Pd and {sup 125}I prostate implants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chibani, Omar; Williamson, Jeffrey F.; Todor, Dorin

2005-08-15

A Monte Carlo study is carried out to quantify the effects of seed anisotropy and interseed attenuation for {sup 103}Pd and {sup 125}I prostate implants. Two idealized and two real prostate implants are considered. Full Monte Carlo simulation (FMCS) of implants (seeds are physically and simultaneously simulated) is compared with isotropic point-source dose-kernel superposition (PSKS) and line-source dose-kernel superposition (LSKS) methods. For clinical pre- and post-procedure implants, the dose to the different structures (prostate, rectum wall, and urethra) is calculated. The discretized volumes of these structures are reconstructed using transrectal ultrasound contours. Local dose differences (PSKS versus FMCS and LSKSmore » versus FMCS) are investigated. The dose contributions from primary versus scattered photons are calculated separately. For {sup 103}Pd, the average absolute total dose difference between FMCS and PSKS can be as high as 7.4% for the idealized model and 6.1% for the clinical preprocedure implant. Similarly, the total dose difference is lower for the case of {sup 125}I: 4.4% for the idealized model and 4.6% for a clinical post-procedure implant. Average absolute dose differences between LSKS and FMCS are less significant for both seed models: 3 to 3.6% for the idealized models and 2.9 to 3.2% for the clinical plans. Dose differences between PSKS and FMCS are due to the absence of both seed anisotropy and interseed attenuation modeling in the PSKS approach. LSKS accounts for seed anisotropy but not for the interseed effect, leading to systematically overestimated dose values in comparison with the more accurate FMCS method. For both idealized and clinical implants the dose from scattered photons represent less than 1/3 of the total dose. For all studied cases, LSKS prostate DVHs overestimate D{sub 90} by 2 to 5% because of the missing interseed attenuation effect. PSKS and LSKS predictions of V{sub 150} and V{sub 200} are overestimated by up

Continuous Low-dose-rate Irradiation of Iodine-125 Seeds Inhibiting Perineural Invasion in Pancreatic Cancer.

PubMed

Lu, Zheng; Dong, Teng-Hui; Si, Pei-Ren; Shen, Wei; Bi, Yi-Liang; Min, Min; Chen, Xin; Liu, Yan

2016-10-20

Perineural invasion (PNI) is a histopathological characteristic of pancreatic cancer (PanCa). The aim of this study was to observe the treatment effect of continuous low-dose-rate (CLDR) irradiation to PNI and assess the PNI-related pain relief caused by iodine-125 ( 125 I) seed implantation. The in vitro PNI model established by co-culture with dorsal root ganglion (DRG) and cancer cells was interfered under 2 and 4 Gy of 125 I seeds CLDR irradiation. The orthotopic models of PNI were established, and 125 I seeds were implanted in tumor. The PNI-related molecules were analyzed. In 30 patients with panCa, the pain relief was assessed using a visual analog scale (VAS). Pain intensity was measured before and 1 week, 2 weeks, and 1, 3, and 6 months after 125 I seed implantation. The co-culture of DRG and PanCa cells could promote the growth of PanCa cells and DRG neurites. In co-culture groups, the increased number of DRG neurites and pancreatic cells in radiation group was significantly less. In orthotopic models, the PNI-positive rate in radiation and control group was 3/11 and 7/11; meanwhile, the degrees of PNI between radiation and control groups was significant difference (P < 0.05). At week 2, the mean VAS pain score in patients decreased by 50% and significantly improved than the score at baseline (P < 0.05). The pain scores were lower in all patients, and the pain-relieving effect was retained about 3 months. The CLDR irradiation could inhibit PNI of PanCa with the value of further study. The CLDR irradiation could do great favor in preventing local recurrence and alleviating pain.

A simple modification of TG-43 based brachytherapy dosimetry with improved fitting functions: application to the selectSeed source.

PubMed

Juan-Senabre, Xavier J; Porras, Ignacio; Lallena, Antonio M

2013-06-01

A variation of TG-43 protocol for seeds with cylindrical symmetry aiming at a better description of the radial and anisotropy functions is proposed. The TG-43 two dimensional formalism is modified by introducing a new anisotropy function. Also new fitting functions that permit a more robust description of the radial and anisotropy functions than usual polynomials are studied. The relationship between the new anisotropy function and the anisotropy factor included in the one-dimensional TG-43 formalism is analyzed. The new formalism is tested for the (125)I Nucletron selectSeed brachytherapy source, using Monte Carlo simulations performed with PENELOPE. The goodness of the new parameterizations is discussed. The results obtained indicate that precise fits can be achieved, with a better description than that provided by previous parameterizations. Special care has been taken in the description and fitting of the anisotropy factor near the source. The modified formalism shows advantages with respect to the usual one in the description of the anisotropy functions. The new parameterizations obtained can be easily implemented in the clinical planning calculation systems, provided that the ratio between geometry factors is also modified according to the new dose rate expression. Copyright © 2012 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

[CT guidance 125I seed implantation for pelvic recurrent rectal cancer assisted by 3D printing individual non-coplanar template].

PubMed

Wang, H; Wang, J J; Jiang, Y L; Tian, S Q; Ji, Z; Guo, F X; Sun, H T; Fan, J H; Xu, Y P

2016-12-20

Objective: To analyze the difference of dosimetric parameters between pre-plan and post-plan of 125 I radioactive seed implantation assisted by 3D printing individual non-coplanar template (3D printing template) for locally recurrent rectal cancer (LRRC). Methods: From February 2016 to April 2016, a total of 10 patients with locally recurrent rectal cancer received 125 I seeds implantation under CT guidance assisted by 3D printing template in Department of Radiation Oncology, Peking University Third Hospital.Each patient underwent CT simulation, three-dimentional treatment planning pre-implantation, 3D printing template design, radioactive seed implantation assisted by 3D printing template and dosimetric verification post implantation. The median activity of seed was 0.63 mCi (0.58 to 0.7 mCi) (2.15- 2.59×10 7 Bq), and the median number of seeds was 80 (19 to 192). D 90 , D 100 , V 100 , V 150 , CI, EI, HI, D 5cc , D 2cc of bladder and bowel of pre-plan and post-plan were calculated, respectively.Paired t test was used to evaluate the difference of dosimetric parameters between pre-plan and post-plan. Results: The median D 90 of pre-plan and post-plan were 13 761.0 and 12 798.8 cGy, respectively.The median D 100 of pre-plan and post-plan were 5 293.6 and 5 397.9 cGy, respectively.The median V 100 of pre-plan and post-plan were 90.0% and 90.0%, respectively.The median V 150 of pre-plan and post-plan were 63.8% and 62.4%, respectively.The median CI of pre-plan and post-plan were 0.73 and 0.67.The median EI of pre-plan and post-plan were 0.22 and 0.30, respectively. The median HI of pre-plan and post-plan were 0.29 and 0.31.The median bladder D 2cc of pre-plan and post-plan were 3 088.8 and 4 240.4 cGy, respectively.The median bowel D 2cc of pre-plan and post-plan were 7 051.6 and 7 903.9 cGy, respectively. Conclusions: 3D printing template might be helpful for locally recurrent rectal cancer patients who received 125 I radioactive seed implantation assisted by 3D

Spectroscopic characterization of low dose rate brachytherapy sources

NASA Astrophysics Data System (ADS)

Beach, Stephen M.

The low dose rate (LDR) brachytherapy seeds employed in permanent radioactive-source implant treatments usually use one of two radionuclides, 125I or 103Pd. The theoretically expected source spectroscopic output from these sources can be obtained via Monte Carlo calculation based upon seed dimensions and materials as well as the bare-source photon emissions for that specific radionuclide. However the discrepancies resulting from inconsistent manufacturing of sources in comparison to each other within model groups and simplified Monte Carlo calculational geometries ultimately result in undesirably large uncertainties in the Monte Carlo calculated values. This dissertation describes experimentally attained spectroscopic outputs of the clinically used brachytherapy sources in air and in liquid water. Such knowledge can then be applied to characterize these sources by a more fundamental and metro logically-pure classification, that of energy-based dosimetry. The spectroscopic results contained within this dissertation can be utilized in the verification and benchmarking of Monte Carlo calculational models of these brachytherapy sources. This body of work was undertaken to establish a usable spectroscopy system and analysis methods for the meaningful study of LDR brachytherapy seeds. The development of a correction algorithm and the analysis of the resultant spectroscopic measurements are presented. The characterization of the spectrometer and the subsequent deconvolution of the measured spectrum to obtain the true spectrum free of any perturbations caused by the spectrometer itself is an important contribution of this work. The approach of spectroscopic deconvolution that was applied in this work is derived in detail and it is applied to the physical measurements. In addition, the spectroscopically based analogs to the LDR dosimetry parameters that are currently employed are detailed, as well as the development of the theory and measurement methods to arrive at these

Comparison of Dosimetric and Biologic Effective Dose Parameters for Prostate and Urethra Using {sup 131}Cs and {sup 125}I for Prostate Permanent Implant Brachytherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sahgal, Arjun; Department of Radiation Oncology, Odette Cancer Centre at Sunnybrook Hospital, University of Toronto, Toronto, ON; Jabbari, Siavash

2008-09-01

Purpose: To compare the urethral and prostate absolute and biologic effective doses (BEDs) for {sup 131}Cs and {sup 125}I prostate permanent implant brachytherapy (PPI). Methods and Materials: Eight previously implanted manually planned {sup 125}I PPI patients were replanned manually with {sup 131}Cs, and re-planned using Inverse Planning Simulated Annealing. {sup 131}Cs activity and the prescribed dose (115 Gy) were determined from that recommended by IsoRay. The BED was calculated for the prostate and urethra using an {alpha}/{beta} ratio of 2 and was also calculated for the prostate using an {alpha}/{beta} ratio of 6 and a urethral {alpha}/{beta} ratio of 2.more » The primary endpoints of this study were the prostate D{sub 90} BED (pD{sub 90}BED) and urethral D{sub 30} BED normalized to the maximal potential prostate D{sub 90} BED (nuD{sub 30}BED). Results: The manual plan comparison ({alpha}/{beta} = 2) yielded no significant difference in the prostate D{sub 90} BED (median, 192 Gy{sub 2} for both isotopes). No significant difference was observed for the nuD{sub 30}BED (median, 199 Gy{sub 2} and 202 Gy{sub 2} for {sup 125}I and {sup 131}Cs, respectively). For the inverse planning simulated annealing plan comparisons ({alpha}/{beta} 2), the prostate D{sub 90} BED was significantly lower with {sup 131}Cs than with {sup 125}I (median, 177 Gy{sub 2} vs. 187 Gy{sub 2}, respectively; p = 0.01). However, the nuD{sub 30}BED was significantly greater with {sup 131}Cs than with {sup 125}I (median, 192 Gy{sub 2} vs. 189 Gy{sub 2}, respectively; p = 0.01). Both the manual and the inverse planning simulated annealing plans resulted in a significantly lower prostate D{sub 90} BED (p = 0.01) and significantly greater nuD{sub 30}BED for {sup 131}Cs (p = 0.01), compared with {sup 125}I, when the prostate {alpha}/{beta} ratio was 6 and the urethral {alpha}/{beta} ratio was 2. Conclusion: This report highlights the controversy in comparing the dose to both the prostate and the

Photon counting readout pixel array in 0.18-μm CMOS technology for on-line gamma-ray imaging of 103palladium seeds for permanent breast seed implant (PBSI) brachytherapy

NASA Astrophysics Data System (ADS)

Goldan, A. H.; Karim, K. S.; Reznik, A.; Caldwell, C. B.; Rowlands, J. A.

2008-03-01

Permanent breast seed implant (PBSI) brachytherapy technique was recently introduced as an alternative to high dose rate (HDR) brachytherapy and involves the permanent implantation of radioactive 103Palladium seeds into the surgical cavity of the breast for cancer treatment. To enable accurate seed implantation, this research introduces a gamma camera based on a hybrid amorphous selenium detector and CMOS readout pixel architecture for real-time imaging of 103Palladium seeds during the PBSI procedure. A prototype chip was designed and fabricated in 0.18-μm n-well CMOS process. We present the experimental results obtained from this integrated photon counting readout pixel.

The difference of scoring dose to water or tissues in Monte Carlo dose calculations for low energy brachytherapy photon sources.

PubMed

Landry, Guillaume; Reniers, Brigitte; Pignol, Jean-Philippe; Beaulieu, Luc; Verhaegen, Frank

2011-03-01

The goal of this work is to compare D(m,m) (radiation transported in medium; dose scored in medium) and D(w,m) (radiation transported in medium; dose scored in water) obtained from Monte Carlo (MC) simulations for a subset of human tissues of interest in low energy photon brachytherapy. Using low dose rate seeds and an electronic brachytherapy source (EBS), the authors quantify the large cavity theory conversion factors required. The authors also assess whether ap plying large cavity theory utilizing the sources' initial photon spectra and average photon energy induces errors related to spatial spectral variations. First, ideal spherical geometries were investigated, followed by clinical brachytherapy LDR seed implants for breast and prostate cancer patients. Two types of dose calculations are performed with the GEANT4 MC code. (1) For several human tissues, dose profiles are obtained in spherical geometries centered on four types of low energy brachytherapy sources: 125I, 103Pd, and 131Cs seeds, as well as an EBS operating at 50 kV. Ratios of D(w,m) over D(m,m) are evaluated in the 0-6 cm range. In addition to mean tissue composition, compositions corresponding to one standard deviation from the mean are also studied. (2) Four clinical breast (using 103Pd) and prostate (using 125I) brachytherapy seed implants are considered. MC dose calculations are performed based on postimplant CT scans using prostate and breast tissue compositions. PTV D90 values are compared for D(w,m) and D(m,m). (1) Differences (D(w,m)/D(m,m)-1) of -3% to 70% are observed for the investigated tissues. For a given tissue, D(w,m)/D(m,m) is similar for all sources within 4% and does not vary more than 2% with distance due to very moderate spectral shifts. Variations of tissue composition about the assumed mean composition influence the conversion factors up to 38%. (2) The ratio of D90(w,m) over D90(m,m) for clinical implants matches D(w,m)/D(m,m) at 1 cm from the single point sources, Given

Surface coating for prevention of metallic seed migration in tissues

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Hyunseok; Park, Jong In; Lee, Won Seok

Purpose: In radiotherapy, metallic implants often detach from their deposited sites and migrate to other locations. This undesirable migration could cause inadequate dose coverage for permanent brachytherapy and difficulties in image-guided radiation delivery for patients. To prevent migration of implanted seeds, the authors propose a potential strategy to use a biocompatible and tissue-adhesive material called polydopamine. Methods: In this study, nonradioactive dummy seeds that have the same geometry and composition as commercial I-125 seeds were coated in polydopamine. Using scanning electron microscopy and x-ray photoelectron spectroscopy, the surface of the polydopamine-coated and noncoated seeds was characterized. The detachment stress betweenmore » the two types of seeds and the tissue was measured. The efficacy of polydopamine-coated seed was investigated through in vitro migration tests by tracing the seed location after tissue implantation and shaking for given times. The cytotoxicity of the polydopamine coating was also evaluated. Results: The results of the coating characterization have shown that polydopamine was successfully coated on the surface of the seeds. In the adhesion test, the polydopamine-coated seeds had 2.1-fold greater detachment stress than noncoated seeds. From the in vitro test, it was determined that the polydopamine-coated seed migrated shorter distances than the noncoated seed. This difference was increased with a greater length of time after implantation. Conclusions: The authors suggest that polydopamine coating is an effective technique to prevent migration of implanted seeds, especially for permanent prostate brachytherapy.« less

Optimal matching for prostate brachytherapy seed localization with dimension reduction.

PubMed

Lee, Junghoon; Labat, Christian; Jain, Ameet K; Song, Danny Y; Burdette, Everette C; Fichtinger, Gabor; Prince, Jerry L

2009-01-01

In prostate brachytherapy, x-ray fluoroscopy has been used for intra-operative dosimetry to provide qualitative assessment of implant quality. More recent developments have made possible 3D localization of the implanted radioactive seeds. This is usually modeled as an assignment problem and solved by resolving the correspondence of seeds. It is, however, NP-hard, and the problem is even harder in practice due to the significant number of hidden seeds. In this paper, we propose an algorithm that can find an optimal solution from multiple projection images with hidden seeds. It solves an equivalent problem with reduced dimensional complexity, thus allowing us to find an optimal solution in polynomial time. Simulation results show the robustness of the algorithm. It was validated on 5 phantom and 18 patient datasets, successfully localizing the seeds with detection rate of > or = 97.6% and reconstruction error of < or = 1.2 mm. This is considered to be clinically excellent performance.

NEW ULTRA-WIDE-FIELD ANGIOGRAPHIC GRADING SCHEME FOR RADIATION RETINOPATHY AFTER IODINE-125 BRACHYTHERAPY FOR UVEAL MELANOMA.

PubMed

McCannel, Tara A; Kim, EunAh; Kamrava, Mitchell; Lamb, James; Caprioli, Joseph; Yang, Dong; McCannel, Colin A

2017-10-06

Radiation retinopathy remains incompletely characterized and may cause severe vision loss. Ultra-wide-field fluorescein angiography provides a pan-fundus view of vascular alterations caused by radiation treatment and may predict visual and ocular outcomes. We have developed a grading scheme to describe pan-fundus severity and to predict the progression of radiation retinopathy in patients treated for uveal melanoma with iodine-125 brachytherapy. A retrospective review of patients treated with standard iodine-125 brachytherapy for uveal melanoma at the Ophthalmic Oncology Center at the University of California, Los Angeles, who had undergone both baseline and postbrachytherapy ultra-wide-field fluorescein angiography. A grading scheme was devised based on observations of vascular leakage, retinal perfusion status, and retinal proliferation. The correlation of grade severity with patient characteristics, tumor features, visual acuity, optical coherence tomography findings, and neovascular glaucoma was measured with chi-square and one-way analysis of variance analyses. Sixty-seven patients were identified for review. Consistent wide-field angiographic patterns after brachytherapy were observed and graded as follows: Grade 0: normal; Grade 1: late foveal leakage; Grade 2: late peripheral leakage; Grade 3: presence of nonperfusion; and Grade 4: retinal neovascularization. Six eyes (8.9%) were Grade 0; 16 (23.8%) were Grade 1; 25 (37.3%) were Grade 2; 16 (23.4%) were Grade 3; and 4 (6.0%) were Grade 4. Higher grade radiation severity correlated significantly with duration of follow-up (P < 0.02); younger age (P = 0.035); worse visual acuity (P = 0.001); cystoid macular edema or atrophy on optical coherence tomography (P < 0.0001); and neovascular glaucoma (P = 0.003). Wide-field fluorescein angiography revealed distinct fundus-wide patterns of vascular damage, which were progressive in nature in eyes treated with iodine-125 brachytherapy for uveal melanoma and correlated

Seed Placement in Permanent Breast Seed Implant Brachytherapy: Are Concerns Over Accuracy Valid?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morton, Daniel, E-mail: dmorton@bccancer.bc.ca; Department of Physics and Astronomy, University of Victoria, Victoria, British Columbia; Hilts, Michelle

Purpose: To evaluate seed placement accuracy in permanent breast seed implant brachytherapy (PBSI), to identify any systematic errors and evaluate their effect on dosimetry. Methods and Materials: Treatment plans and postimplant computed tomography scans for 20 PBSI patients were spatially registered and used to evaluate differences between planned and implanted seed positions, termed seed displacements. For each patient, the mean total and directional seed displacements were determined in both standard room coordinates and in needle coordinates relative to needle insertion angle. Seeds were labeled according to their proximity to the anatomy within the breast, to evaluate the influence of anatomicmore » regions on seed placement. Dosimetry within an evaluative target volume (seroma + 5 mm), skin, breast, and ribs was evaluated to determine the impact of seed placement on the treatment. Results: The overall mean (±SD) difference between implanted and planned positions was 9 ± 5 mm for the aggregate seed population. No significant systematic directional displacements were observed for this whole population. However, for individual patients, systematic displacements were observed, implying that intrapatient offsets occur during the procedure. Mean displacements for seeds in the different anatomic areas were not found to be significantly different from the mean for the entire seed population. However, small directional trends were observed within the anatomy, potentially indicating some bias in the delivery. Despite observed differences between the planned and implanted seed positions, the median (range) V{sub 90} for the 20 patients was 97% (66%-100%), and acceptable dosimetry was achieved for critical structures. Conclusions: No significant trends or systematic errors were observed in the placement of seeds in PBSI, including seeds implanted directly into the seroma. Recorded seed displacements may be related to intrapatient setup adjustments. Despite

Patient-reported health-related quality of life for men treated with low-dose-rate prostate brachytherapy as monotherapy with 125-iodine, 103-palladium, or 131-cesium: Results of a prospective phase II study.

PubMed

Blanchard, Pierre; Pugh, Thomas J; Swanson, David A; Mahmood, Usama; Chen, Hsiang-Chun; Wang, Xuemei; Graber, William J; Kudchadker, Rajat J; Bruno, Teresa; Feeley, Thomas; Frank, Steven J

To compare quality of life (QoL) after brachytherapy with one of the three approved radioactive isotopes. Patients with mostly favorable intermediate-risk prostate cancer were treated on this prospective phase II trial with brachytherapy as monotherapy, without hormonal therapy. QoL was recorded at baseline and each follow-up by using the Expanded Prostate Cancer Index Composite instrument. The minimal clinically important difference was defined as half the standard deviation of the baseline score for each domain. Mixed effect models were used to compare the different isotopes, and time-driven activity-based costing was used to compute costs. From 2006 to 2013, 300 patients were treated with iodine-125 (I-125, n = 98, prescribed dose [PD] = 145 Gy), palladium-103 (Pd-103, n = 102, PD = 125 Gy), or cesium-131 (Cs-131, n = 100, PD = 115 Gy). Median age was 64.9 years. Median follow-up time was 5.1 years for the entire cohort, and 7.1, 4.8 and 3.3 years for I-125, Pd-103, and Cs-131 groups, respectively. All three isotope groups showed an initial drop in QoL at first follow-up, which gradually improved over the first 2 years for urinary and bowel domains. QoL profiles were similar between I-125 and Pd-103, whereas Cs-131 showed a statistically significant decrease in QoL regarding bowel and sexual function at 12 months compared with Pd-103. However, these differences did not reach the minimal clinically important difference. Compared with I-125, the use of Pd-103 or Cs-131 resulted in cost increases of 18% and 34% respectively. The three different isotopes produced a similar QoL profile. Statistically significant differences favored Pd-103/I-125 over Cs-131 for bowel and sexual QoL, but this did not reach clinical significance. Copyright © 2017 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

The side effects and complications of percutaneous iodine-125 seeds implantation under CT-guide for patients with advanced pancreatic cancer.

PubMed

Lv, Wei-Fu; Lu, Dong; Xiao, Jing-Kun; Mukhiya, Gauri; Tan, Zhong-Xiao; Cheng, De-Lei; Zhou, Chun-Ze; Zhang, Xing-Min; Zhang, Zheng-Feng; Hou, Chang-Long

2017-12-01

The present study investigates the side effects and complications of computed tomography (CT)-guided percutaneous iodine-125 (I-125) seeds implantation for advanced pancreatic cancer. The clinical data were retrospectively analyzed for patients treated with implantation of I-125 seeds under CT-guide in our hospital from May 2010 to April 2015. The side effects and complications were collected and their possible reasons were analyzed. A total of 78 patients were enrolled. The side effects were categorized as fever in 29 cases (37.18%), abdominal pain in 26 cases (33.33%), nausea and vomiting in 9 cases (11.54%), diarrhea in 5 cases (6.41%), and constipation in 4 cases (5.13%). Complications were composed of pancreatitis in 9 cases (11.54%), infection in 5 cases (6.41%), seed migration in 2 cases (2.56%), intestinal perforation in 1 case (1.28%), and intestinal obstruction in 1 case. The incidence of complication was 23.08% (18/78). The difference in incidence of complication was statistically significant between patients implanted with ≤27 seeds and those with >27 seeds (P = .032). The side effects and complications frequently occur in implantation of I-125 seeds for patients with advanced pancreatic cancer. More concern should be given to the patients treated by this technique. Copyright © 2017 The Authors. Published by Wolters Kluwer Health, Inc. All rights reserved.

SU-E-T-55: Biological Equivalent Dose (BED) Comparison Between Permanent Interstitial Brachytherapy and Conventional External Beam Radiotherapy for Prostate Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, X; Rahimian, J; Cosmatos, H

2014-06-01

Purpose: The goal of this research is to calculate and compare the Biological Equivalent Dose (BED) between permanent prostate Iodine-125 implant brachytherapy as monotherapy with the BED of conventional external beam radiation therapy (EBRT). Methods: A retrospective study of 605 patients treated with Iodine-125 seed implant was performed in which physician A treated 274 patients and physician B treated 331 patients. All the Brachytherapy treatment plans were created using VariSeed 8 planning system. The Iodine-125 seed source activities and loading patterns varied slightly between the two physicians. The prescription dose is 145 Gy to PTV for each patient. The BEDmore » and Tumor Control Probability (TCP) were calculated based on the TG 137 formulas. The BED for conventional EBRT of the prostate given in our institution in 2Gy per fraction for 38 fractions was calculated and compared. Results: Physician A treated 274 patients with an average BED of 123.92±0.87 Gy and an average TCP of 99.20%; Physician B treated 331 patients with an average BED of 124.87±1.12 Gy and an average TCP of 99.30%. There are no statistically significant differences (T-Test) between the BED and TCP values calculated for these two group patients.The BED of the patients undergoing conventional EBRT is calculated to be 126.92Gy. The BED of the patients treated with permanent implant brachytherapy and EBRT are comparable. Our BED and TCP values are higher than the reported values by TG 137 due to higher Iodine-125 seed activity used in our institution. Conclusion: We calculated the BED,a surrogate of the biological response to a permanent prostate brachytherapy using TG 137 formulas and recommendation. The TCP of better than 99% is calculated for these patients. A clinical outcome study of these patients correlating the BED and TCP values with PSA and Gleason Levels as well as patient survival is warranted.« less

Prostate Brachytherapy Seed Reconstruction with Gaussian Blurring and Optimal Coverage Cost

PubMed Central

Lee, Junghoon; Liu, Xiaofeng; Jain, Ameet K.; Song, Danny Y.; Burdette, E. Clif; Prince, Jerry L.; Fichtinger, Gabor

2009-01-01

Intraoperative dosimetry in prostate brachytherapy requires localization of the implanted radioactive seeds. A tomosynthesis-based seed reconstruction method is proposed. A three-dimensional volume is reconstructed from Gaussian-blurred projection images and candidate seed locations are computed from the reconstructed volume. A false positive seed removal process, formulated as an optimal coverage problem, iteratively removes “ghost” seeds that are created by tomosynthesis reconstruction. In an effort to minimize pose errors that are common in conventional C-arms, initial pose parameter estimates are iteratively corrected by using the detected candidate seeds as fiducials, which automatically “focuses” the collected images and improves successive reconstructed volumes. Simulation results imply that the implanted seed locations can be estimated with a detection rate of ≥ 97.9% and ≥ 99.3% from three and four images, respectively, when the C-arm is calibrated and the pose of the C-arm is known. The algorithm was also validated on phantom data sets successfully localizing the implanted seeds from four or five images. In a Phase-1 clinical trial, we were able to localize the implanted seeds from five intraoperative fluoroscopy images with 98.8% (STD=1.6) overall detection rate. PMID:19605321

Synthesis of (125) I-lamivudine and (125) I-lamivudine-ursodeoxycholic acid codrug.

PubMed

Motaleb, M A; Abo-Kul, M; Ibrahim, Samy M; Saad, Shokry M; Arafat, Muhammad

2016-09-01

The preparation of (125) I-lamivudine ((125) I-3TC) and (125) I-lamivudine-ursodeoxycholic acid codrug ((125) I-3TC-UDCA), suitable for comparative biodistribution studies, is described. The synthesis of the unlabeled precursor 3TC-UDCA proceeds in an 11.6% yield, and the radiolabelling yields for (125) I-3TC and (125) I-3TC-UDCA were 89 and 92%, respectively. The final products are radiochemically pure (greater than 98%). Copyright © 2016 John Wiley & Sons, Ltd.

Establishing High-Quality Prostate Brachytherapy Using a Phantom Simulator Training Program

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thaker, Nikhil G.; Kudchadker, Rajat J.; Swanson, David A.

2014-11-01

Purpose: To design and implement a unique training program that uses a phantom-based simulator to teach the process of prostate brachytherapy (PB) quality assurance and improve the quality of education. Methods and Materials: Trainees in our simulator program were practicing radiation oncologists, radiation oncology residents, and fellows of the American Brachytherapy Society. The program emphasized 6 core areas of quality assurance: patient selection, simulation, treatment planning, implant technique, treatment evaluation, and outcome assessment. Using the Iodine 125 ({sup 125}I) preoperative treatment planning technique, trainees implanted their ultrasound phantoms with dummy seeds (ie, seeds with no activity). Pre- and postimplant dosimetric parametersmore » were compared and correlated using regression analysis. Results: Thirty-one trainees successfully completed the simulator program during the period under study. The mean phantom prostate size, number of seeds used, and total activity were generally consistent between trainees. All trainees met the V100 >95% objective both before and after implantation. Regardless of the initial volume of the prostate phantom, trainees' ability to cover the target volume with at least 100% of the dose (V100) was not compromised (R=0.99 pre- and postimplant). However, the V150 had lower concordance (R=0.37) and may better reflect heterogeneity control of the implant process. Conclusions: Analysis of implants from this phantom-based simulator shows a high degree of consistency between trainees and uniformly high-quality implants with respect to parameters used in clinical practice. This training program provides a valuable educational opportunity that improves the quality of PB training and likely accelerates the learning curve inherent in PB. Prostate phantom implantation can be a valuable first step in the acquisition of the required skills to safely perform PB.« less

Monte Carlo calculated microdosimetric spread for cell nucleus-sized targets exposed to brachytherapy 125I and 192Ir sources and 60Co cell irradiation.

PubMed

Villegas, Fernanda; Tilly, Nina; Ahnesjö, Anders

2013-09-07

The stochastic nature of ionizing radiation interactions causes a microdosimetric spread in energy depositions for cell or cell nucleus-sized volumes. The magnitude of the spread may be a confounding factor in dose response analysis. The aim of this work is to give values for the microdosimetric spread for a range of doses imparted by (125)I and (192)Ir brachytherapy radionuclides, and for a (60)Co source. An upgraded version of the Monte Carlo code PENELOPE was used to obtain frequency distributions of specific energy for each of these radiation qualities and for four different cell nucleus-sized volumes. The results demonstrate that the magnitude of the microdosimetric spread increases when the target size decreases or when the energy of the radiation quality is reduced. Frequency distributions calculated according to the formalism of Kellerer and Chmelevsky using full convolution of the Monte Carlo calculated single track frequency distributions confirm that at doses exceeding 0.08 Gy for (125)I, 0.1 Gy for (192)Ir, and 0.2 Gy for (60)Co, the resulting distribution can be accurately approximated with a normal distribution. A parameterization of the width of the distribution as a function of dose and target volume of interest is presented as a convenient form for the use in response modelling or similar contexts.

Optical fibre luminescence sensor for real-time LDR brachytherapy dosimetry

NASA Astrophysics Data System (ADS)

Woulfe, P.; Sullivan, F. J.; O'Keeffe, S.

2016-05-01

An optical fibre sensor for monitoring low dose radiation is presented. The sensor is based on a scintillation material embedded within the optical fibre core, which emits visible light when exposed to low level ionising radiation. The incident level of ionising radiation can be determined by analysing the optical emission. An optical fibre sensor is presented, based on radioluminescence whereby radiation sensitive scintillation material, terbium doped gadolinium oxysulphide (Gd2O2S:Tb), is embedded in a cavity of 250μm of a 500μm plastic optical fibre. The sensor is designed for in-vivo monitoring of the radiation dose during radio-active seed implantation for brachytherapy, in prostate cancer treatment, providing oncologists with real-time information of the radiation dose to the target area and/or nearby critical structures. The radiation from the brachytherapy seeds causes emission of visible light from the scintillation material through the process of radioluminescence, which penetrates the fibre, propagating along the optical fibre for remote detection using a multi-pixel photon counter. The sensor demonstrates a high sensitivity to Iodine-125, the radioactive source most commonly used in brachytherapy for treating prostate cancer.

Brachytherapy Application With In Situ Dose Painting Administered by Gold Nanoparticle Eluters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sinha, Neeharika; Cifter, Gizem; Department of Radiation Oncology, Dana-Farber Cancer Institute, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts

Purpose: Recent studies show promise that administering gold nanoparticles (GNP) to tumor cells during brachytherapy could significantly enhance radiation damage to the tumor. A new strategy proposed for sustained administration of the GNP in prostate tumors is to load them into routinely used brachytherapy spacers for customizable in situ release after implantation. This in silico study investigated the intratumor biodistribution and corresponding dose enhancement over time due to GNP released from such GNP-loaded brachytherapy spacers (GBS). Method and Materials: An experimentally determined intratumoral diffusion coefficient (D) for 10-nm nanoparticles was used to estimate D for other sizes by using themore » Stokes-Einstein equation. GNP concentration profiles, obtained using D, were then used to calculate the corresponding dose enhancement factor (DEF) for each tumor voxel, using dose painting-by-numbers approach, for times relevant to the considered brachytherapy sources' lifetimes. The investigation was carried out as a function of GNP size for the clinically applicable low-dose-rate brachytherapy sources iodine-125 (I-125), palladium-103 (Pd-103), and cesium-131 (Cs-131). Results: Results showed that dose enhancement to tumor voxels and subvolumes during brachytherapy can be customized by varying the size of GNP released or eluted from the GBS. For example, using a concentration of 7 mg/g GNP, significant DEF (>20%) could be achieved 5 mm from a GBS after 5, 12, 25, 46, 72, 120, and 195 days, respectively, for GNP sizes of 2, 5, 10, 20, 30, and 50 nm and for 80 nm when treating with I-125. Conclusions: Analyses showed that using Cs-131 provides the highest dose enhancement to tumor voxels. However, given its relatively longer half-life, I-125 presents the most flexibility for customizing the dose enhancement as a function of GNP size. These findings provide a useful reference for further work toward development of potential new brachytherapy

SU-E-J-215: Towards MR-Only Image Guided Identification of Calcifications and Brachytherapy Seeds: Application to Prostate and Breast LDR Implant Dosimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elzibak, A; Fatemi-Ardekani, A; Soliman, A

Purpose: To identify and analyze the appearance of calcifications and brachytherapy seeds on magnitude and phase MRI images and to investigate whether they can be distinguished from each other on corrected phase images for application to prostate and breast low dose rate (LDR) implant dosimetry. Methods: An agar-based gel phantom containing two LDR brachytherapy seeds (Advantage Pd-103, IsoAid, 0.8mm diameter, 4.5mm length) and two spherical calcifications (large: 7mm diameter and small: 4mm diameter) was constructed and imaged on a 3T Philips MR scanner using a 16-channel head coil and a susceptibility weighted imaging (SWI) sequence (2mm slices, 320mm FOV, TR/more » TE= 26.5/5.3ms, 15 degree flip angle). The phase images were unwrapped and corrected using a 32×32, 2D Hanning high pass filter to remove background phase noise. Appearance of the seeds and calcifications was assessed visually and quantitatively using Osirix (http://www.osirix-viewer.com/). Results: As expected, calcifications and brachytherapy seeds appeared dark (hypointense) relative to the surrounding gel on the magnitude MRI images. The diameter of each seed without the surrounding artifact was measured to be 0.1 cm on the magnitude image, while diameters of 0.79 and 0.37 cm were measured for the larger and smaller calcifications, respectively. On the corrected phase images, the brachytherapy seeds and the calcifications appeared bright (hyperintense). The diameter of the seeds was larger on the phase images (0.17 cm) likely due to the dipole effect. Conclusion: MRI has the best soft tissue contrast for accurate organ delineation leading to most accurate implant dosimetry. This work demonstrated that phase images can potentially be useful in identifying brachytherapy seeds and calcifications in the prostate and breast due to their bright appearance, which helps in their visualization and quantification for accurate dosimetry using MR-only. Future work includes optimizing phase filters to best

Directional interstitial brachytherapy from simulation to application

NASA Astrophysics Data System (ADS)

Lin, Liyong

Organs at risk (OAR) are sometimes adjacent to or embedded in or overlap with the clinical target volume (CTV) to be treated. The purpose of this PhD study is to develop directionally low energy gamma-emitting interstitial brachytherapy sources. These sources can be applied between OAR to selectively reduce hot spots in the OARs and normal tissues. The reduction of dose over undesired regions can expand patient eligibility or reduce toxicities for the treatment by conventional interstitial brachytherapy. This study covers the development of a directional source from design optimization to construction of the first prototype source. The Monte Carlo code MCNP was used to simulate the radiation transport for the designs of directional sources. We have made a special construction kit to assemble radioactive and gold-shield components precisely into D-shaped titanium containers of the first directional source. Directional sources have a similar dose distribution as conventional sources on the treated side but greatly reduced dose on the shielded side, with a sharp dose gradient between them. A three-dimensional dose deposition kernel for the 125I directional source has been calculated. Treatment plans can use both directional and conventional 125I sources at the same source strength for low-dose-rate (LDR) implants to optimize the dose distributions. For prostate tumors, directional 125I LDR brachytherapy can potentially reduce genitourinary and gastrointestinal toxicities and improve potency preservation for low risk patients. The combination of better dose distribution of directional implants and better therapeutic ratio between tumor response and late reactions enables a novel temporary LDR treatment, as opposed to permanent or high-dose-rate (HDR) brachytherapy for the intermediate risk T2b and high risk T2c tumors. Supplemental external-beam treatments can be shortened with a better brachytherapy boost for T3 tumors. In conclusion, we have successfully finished the

SU-E-T-259: Development of a Primary Standard for LDR Brachytherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shen, H; McEwen, M

Purpose: The National Research Council initiated a program in 2012 to develop a primary standard to calibrate I-125 and Pd-103 sources used for LDR brachytherapy and disseminate this through calibration services to Canadian users. This will simplify procedures as Canadian cancer centres currently have to ship instruments to the US. Methods: The standard is based on a commercial version of the wide-angle free air chamber (WAFAC) pioneered by NIST. Significant enhancements were implemented to improve signal-to-noise and measurement reproducibility and eliminate electric field effects. Validation of this ionization chamber was then carried out in a low-energy X -ray beam (∼more » 31 keV) where the dose rate had been previously established using the existing NRC primary standard free-air chamber. As a final component of this initial testing, measurements were made with a set of I-125 seeds (with air kerma strength traceable to NIST). Results: Excellent agreement of the two NRC free-air chambers was obtained within the combined standard uncertainty of 0.5 %. However, it was found that the WAFAC response is very sensitive to the beam geometry (distance from the source, diameter of the beam-defining aperture, etc) and Monte Carlo calculations, carried out to evaluate these geometry corrections, have confirmed the experimental results. The results for the seed measurements indicated a precision of better than 1 % is achievable for a reasonable acquisition time and the air kerma strength agreed with the manufacturer (NIST-traceable) value within 2 %. Conclusion: The prototype primary standard for LDR brachytherapy has met accuracy target of 3 % for the determination of air kerma strength. Work is ongoing to refine operation of the device and develop the calibration protocol for clinical users, with an anticipated launch of a calibration service in late 2015.« less

SU-F-BRA-08: An Investigation of Well-Chamber Responses for An Electronic Brachytherapy Source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Culberson, W; Micka, J

Purpose: The aim of this study was to investigate the variation of well-type ionization chamber response between a Xoft Axxent™ electronic brachytherapy (EBT) source and a GE Oncoseed™ 6711 I-125 seed. Methods: A new EBT air-kerma standard has recently been introduced by the National Institute of Standards and Technology (NIST). Historically, the Axxent source strength has been based on a well chamber calibration from an I-125 brachytherapy source due to the lack of a primary standard. Xoft utilizes a calibration procedure that employs a GE 6711 seed calibration as a surrogate standard to represent the air-kerma strength of an Axxentmore » source. This method is based on the premise that the energies of the two sources are similar and thus, a conversion factor would be a suitable interim solution until a NIST standard was established. For this investigation, a number of well chambers of the same model type and three different EBT sources were used to determine NIST-traceable calibration coefficients for both the GE 6711 seed and the Axxent source. The ratio of the two coefficients was analyzed for consistency and also to identify any possible correlations with chamber vintage or the sources themselves. Results: For all well chambers studied, the relative standard deviation of the ratio of calibration coefficients between the two standards is less than 1%. No specific trends were found with the well chamber vintage or between the three different EBT sources used. Conclusion: The variation of well chamber calibration coefficients between a Xoft Axxent™ EBT source versus a GE 6711 Oncoseed™ are consistent across well chamber vintage and between sources. The results of this investigation confirm the underlying assumptions and stability of the surrogate standard currently in use by Xoft, and establishes a migration path for future implementation of the new NIST air kerma standard. This research is supported in part by Xoft, a subsidiary of iCAD.« less

Process for depositing I-125 onto a substrate used to manufacture I-125 sources

DOEpatents

McGovern, James J.; Olynyk, Joseph M.

1988-01-01

The invention relates to a process for depositing I-125 on a substrate which comprises contacting a predetermined surface area of substrate with Xe-125 gas, whereby the Xe-125 decays to I-125 and the I-125 in turn deposits as a solid on the surface of the substrate, the contact being for a time sufficient to deposit at least about 1 microcurie of I-125. I-125 is thereby deposited in a relatively uniform amount over the surface area of the substrate. The substrate is then assayed to determine how much I-125 has been deposited. The substrate is then divided into pieces of measured surface area, each piece therefore containing a measured amount of deposited I-125, and each piece can then be used in the manufacture of an I-125 source.

Intraoperative 3D Navigation for Single or Multiple 125I-Seed Localization in Breast-Preserving Cancer Surgery.

PubMed

Pouw, Bas; de Wit-van der Veen, Linda J; van Duijnhoven, Frederieke; Rutgers, Emiel J Th; Stokkel, Marcel P M; Valdés Olmos, Renato A; Vrancken Peeters, Marie-Jeanne T F D

2016-05-01

Mammographic screening has led to the identification of more women with nonpalpable breast cancer, many of them to be treated with breast-preserving surgery. To accomplish radical tumor excision, adequate localization techniques such as radioactive seed localization (RSL) are required. For RSL, a radioactive I-seed is implanted central in the tumor to enable intraoperative localization using a γ-probe. In case of extensive tumor or multifocal carcinoma, multiple I-seeds can be used to delineate the involved area. Preoperative imaging is performed different from surgical positioning; therefore, exact I-seed depth remains unknown during surgery. Twenty patients (mean age, 56.8 years) with 25 implanted I-seeds scheduled for RSL were included. Sixteen patients had 1 I-seed implanted in the primary lesion, 3 patients had 2 I-seeds, and 1 patient had 3 I-seeds. Freehand SPECT localized I-seeds by measuring γ-counts from different directions, all registered by an optical tracking system. A reconstruction and visualization algorithm enabled 3-dimensional (3D) navigation toward the I-seeds. Freehand SPECT visualized all I-seeds in primary tumors and provided preincision depth information. The deviation, mean (SD), between the freehand SPECT depth and the surgical depth estimation was 1.9 (2.1) mm (range, 0-7 mm). Three-dimensional freehand SPECT was especially useful identifying multiple implanted I-seeds because the conventional γ-probe has more difficulty discriminating I-seeds transcutaneous. Freehand SPECT with 3D navigation is a valuable tool in RSL for both single and multiple implanted I-seeds in breast-preserving cancer surgery. Freehand SPECT provides continuous updating 3D imaging with information about depth and location of the I-seeds contributing to adequate excision of nonpalpable breast cancer.

WE-DE-201-12: Thermal and Dosimetric Properties of a Ferrite-Based Thermo-Brachytherapy Seed

DOE Office of Scientific and Technical Information (OSTI.GOV)

Warrell, G; Shvydka, D; Parsai, E I

Purpose: The novel thermo-brachytherapy (TB) seed provides a simple means of adding hyperthermia to LDR prostate permanent implant brachytherapy. The high blood perfusion rate (BPR) within the prostate motivates the use of the ferrite and conductive outer layer design for the seed cores. We describe the results of computational analyses of the thermal properties of this ferrite-based TB seed in modelled patient-specific anatomy, as well as studies of the interseed and scatter (ISA) effect. Methods: The anatomies (including the thermophysical properties of the main tissue types) and seed distributions of 6 prostate patients who had been treated with LDR brachytherapymore » seeds were modelled in the finite element analysis software COMSOL, using ferrite-based TB and additional hyperthermia-only (HT-only) seeds. The resulting temperature distributions were compared to those computed for patient-specific seed distributions, but in uniform anatomy with a constant blood perfusion rate. The ISA effect was quantified in the Monte Carlo software package MCNP5. Results: Compared with temperature distributions calculated in modelled uniform tissue, temperature distributions in the patient-specific anatomy were higher and more heterogeneous. Moreover, the maximum temperature to the rectal wall was typically ∼1 °C greater for patient-specific anatomy than for uniform anatomy. The ISA effect of the TB and HT-only seeds caused a reduction in D90 similar to that found for previously-investigated NiCu-based seeds, but of a slightly smaller magnitude. Conclusion: The differences between temperature distributions computed for uniform and patient-specific anatomy for ferrite-based seeds are significant enough that heterogeneous anatomy should be considered. Both types of modelling indicate that ferrite-based seeds provide sufficiently high and uniform hyperthermia to the prostate, without excessively heating surrounding tissues. The ISA effect of these seeds is slightly less

A technical evaluation of the Nucletron FIRST system: conformance of a remote afterloading brachytherapy seed implantation system to manufacturer specifications and AAPM Task Group report recommendations.

PubMed

Rivard, Mark J; Evans, Dee-Ann Radford; Kay, Ian

2005-01-01

The Fully Integrated Real-time Seed Treatment (FIRST) system by Nucletron has been available in Europe since November 2001 and is being used more and more in Canada and the United States. Like the conventional transrectal ultrasound implant procedure, the FIRST system utilizes an ultrasound probe, needles, and brachytherapy seeds. However, this system is unique in that it (1) utilizes a low-dose-rate brachytherapy seed remote afterloader (the seedSelectron), (2) utilizes 3D image reconstruction acquired from electromechanically controlled, nonstepping rotation of the ultrasound probe, (3) integrates the control of a remote afterloader with electromechanical control of the ultrasound probe for integrating the clinical procedure into a single system, and (4) automates the transfer of planning information and seed delivery to improve quality assurance and radiation safety. This automated delivery system is specifically intended to address reproducibility and accuracy of seed positioning during implantation. The FIRST computer system includes two software environments: SPOT PRO and seedSelectron; both are used to facilitate treatment planning and brachytherapy seed implantation from beginning to completion of the entire procedure. In addition to these features, the system is reported to meet certain product specifications for seed delivery positioning accuracy and reproducibility, seed calibration accuracy and reliability, and brachytherapy dosimetry calculations. Consequently, a technical evaluation of the FIRST system was performed to determine adherence to manufacturer specifications and to the American Association of Physicists in Medicine (AAPM) Task Group Reports 43, 53, 56, 59, and 64 and recommendations of the American Brachytherapy Society (ABS). The United States Nuclear Regulatory Commission (NRC) has recently added Licensing Guidance for the seedSelectron system under 10 CFR 35.1000. Adherence to licensing guidance is made by referencing applicable AAPM

Evaluating the Phoenix definition of biochemical failure after (125)I prostate brachytherapy: Can PSA kinetics distinguish PSA failures from PSA bounces?

PubMed

Thompson, Anna; Keyes, Mira; Pickles, Tom; Palma, David; Moravan, Veronika; Spadinger, Ingrid; Lapointe, Vincent; Morris, W James

2010-10-01

To evaluate the prostate-specific antigen (PSA) kinetics of PSA failure (PSAf) and PSA bounce (PSAb) after permanent (125)I prostate brachytherapy (PB). The study included 1,006 consecutive low and "low tier" intermediate-risk patients treated with (125)I PB, with a potential minimum follow-up of 4 years. Patients who met the Phoenix definition of biochemical failure (nadir + 2 ng/mL(-1)) were identified. If the PSA subsequently fell to ≤0.5 ng/mL(-1)without intervention, this was considered a PSAb. All others were scored as true PSAf. Patient, tumor and dosimetric characteristics were compared between groups using the chi-square test and analysis of variance to evaluate factors associated with PSAf or PSAb. Median follow-up was 54 months. Of the 1,006 men, 57 patients triggered the Phoenix definition of PSA failure, 32 (56%) were true PSAf, and 25 PSAb (44%). The median time to trigger nadir + 2 was 20.6 months (range, 6-36) vs. 49 mo (range, 12-83) for PSAb vs. PSAf groups (p < 0.001). The PSAb patients were significantly younger (p < 0.0001), had shorter time to reach the nadir (median 6 vs. 11.5 months, p = 0.001) and had a shorter PSA doubling time (p = 0.05). Men younger than age 70 who trigger nadir +2 PSA failure within 38 months of implant have an 80% likelihood of having PSAb and 20% chance of PSAf. With adequate follow-up, 44% of PSA failures by the Phoenix definition in our cohort were found to be benign PSA bounces. Our study reinforces the need for adequate follow-up when reporting PB PSA outcomes, to ensure accurate estimates of treatment efficacy and to avoid unnecessary secondary interventions. 2010. Published by Elsevier Inc. All rights reserved.

Iodine 125 Brachytherapy With Vitrectomy and Silicone Oil in the Treatment of Uveal Melanoma: 1-to-1 Matched Case-Control Series

DOE Office of Scientific and Technical Information (OSTI.GOV)

McCannel, Tara A., E-mail: TMcCannel@jsei.ucla.edu; McCannel, Colin A.

Purpose: We initially reported the radiation-attenuating effect of silicone oil 1000 centistokes for iodine 125. The purpose of this report was to compare the clinical outcomes in case patients who had iodine 125 brachytherapy with vitrectomy and silicone oil 1000 centistokes with the outcomes in matched control patients who underwent brachytherapy alone. Methods and Materials: Consecutive patients with uveal melanoma who were treated with iodine 125 plaque brachytherapy and vitrectomy with silicone oil with minimum 1-year follow-up were included. Control patients who underwent brachytherapy alone were matched for tumor size, location, and sex. Baseline patient and tumor characteristics and tumor response tomore » radiation, final visual acuity, macular status, central macular thickness by ocular coherence tomography (OCT), cataract progression, and metastasis at last follow-up visit were compared. Surgical complications were also determined. Results: Twenty case patients met the inclusion criteria. The average follow-up time was 22.1 months in case patients and 19.4 months in control patients. The final logMAR vision was 0.81 in case patients and 1.1 in control patients (P=.071); 8 case patients and 16 control patients had abnormal macular findings (P=.011); and the average central macular thickness by OCT was 293.2 μm in case patients and 408.5 μm in control patients (P=.016). Eleven case patients (55%) and 1 control patient (5%) had required cataract surgery at last follow-up (P=.002). Four patients in the case group and 1 patient in the control group experienced metastasis (P=.18). Among the cases, intraoperative retinal tear occurred in 3 patients; total serous retinal detachment and macular hole developed in 1 case patient each. There was no case of rhegmatogenous retinal detachment, treatment failure, or local tumor dissemination in case patients or control patients. Conclusions: With up to 3 years of clinical follow-up, silicone oil during

Optical fibre luminescence sensor for real-time LDR brachytherapy dosimetry

NASA Astrophysics Data System (ADS)

Woulfe, P.; O'Keeffe, S.; Sullivan, F. J.

2018-02-01

An optical fibre sensor for monitoring low dose radiation is presented. The sensor is based on a scintillation material embedded within the optical fibre core, which emits visible light when exposed to low level ionising radiation. The incident level of ionising radiation can be determined by analysing the optical emission. An optical fibre sensor is developed, based on radioluminescence whereby radiation sensitive scintillation material, terbium doped gadolinium oxysulphide (Gd2O2S:Tb), is embedded in a cavity of 700μm of a 1mm plastic optical fibre. The sensor is designed for in-vivo monitoring of the radiation dose during radio-active seed implantation for low dose rate (LDR) brachytherapy, in prostate cancer treatment, providing radiation oncologists with real-time information of the radiation dose to the target area and/or nearby organs at risk (OARs). The radiation from the brachytherapy seeds causes emission of visible light from the scintillation material through the process of radioluminescence, which penetrates the fibre, propagating along the optical fibre for remote detection using a multi-pixel photon counter. The sensor demonstrates a high sensitivity to 0.397mCi of Iodine125, the radioactive source most commonly used in brachytherapy for treating prostate cancer.

Outcomes and Control Rates for I-125 Plaque Brachytherapy for Uveal Melanoma: A Community-Based Institutional Experience

PubMed Central

Cook, Taylor

2014-01-01

Purpose. To evaluate our community-based institutional experience with plaque brachytherapy for uveal melanomas with a focus on local control rates, factors impacting disease progression, and dosimetric parameters impacting treatment toxicity. Methods and Materials. Our institution was retrospectively reviewed from 1996 to 2011; all patients who underwent plaque brachytherapy for uveal melanoma were included. Follow-up data were collected regarding local control, distant metastases, and side effects from treatment. Analysis was performed on factors impacting treatment outcomes and treatment toxicity. Results. A total of 107 patients underwent plaque brachytherapy, of which 88 had follow-up data available. Local control at 10 years was 94%. Freedom from progression (FFP) and overall survival at 10 years were 83% and 79%, respectively. On univariate analysis, there were no tumor or dosimetric treatment characteristics that were found to have a prognostic impact on FFP. Brachytherapy treatment was well tolerated, with clinically useful vision (>20/200) maintained in 64% of patients. Statistically significant dosimetric relationships were established with cataract, glaucoma, and retinopathy development (greatest P = 0.05). Conclusions. Treatment with plaque brachytherapy demonstrates excellent outcomes in a community-based setting. It is well tolerated and should remain a standard of care for COMS medium sized tumors. PMID:24734198

Gold nanoparticle‐based brachytherapy enhancement in choroidal melanoma using a full Monte Carlo model of the human eye

PubMed Central

Vaez‐zadeh, Mehdi; Masoudi, S. Farhad; Rahmani, Faezeh; Knaup, Courtney; Meigooni, Ali S.

2015-01-01

The effects of gold nanoparticles (GNPs) in 125I brachytherapy dose enhancement on choroidal melanoma are examined using the Monte Carlo simulation technique. Usually, Monte Carlo ophthalmic brachytherapy dosimetry is performed in a water phantom. However, here, the compositions of human eye have been considered instead of water. Both human eye and water phantoms have been simulated with MCNP5 code. These simulations were performed for a fully loaded 16 mm COMS eye plaque containing 13 125I seeds. The dose delivered to the tumor and normal tissues have been calculated in both phantoms with and without GNPs. Normally, the radiation therapy of cancer patients is designed to deliver a required dose to the tumor while sparing the surrounding normal tissues. However, as the normal and cancerous cells absorbed dose in an almost identical fashion, the normal tissue absorbed radiation dose during the treatment time. The use of GNPs in combination with radiotherapy in the treatment of tumor decreases the absorbed dose by normal tissues. The results indicate that the dose to the tumor in an eyeball implanted with COMS plaque increases with increasing GNPs concentration inside the target. Therefore, the required irradiation time for the tumors in the eye is decreased by adding the GNPs prior to treatment. As a result, the dose to normal tissues decreases when the irradiation time is reduced. Furthermore, a comparison between the simulated data in an eye phantom made of water and eye phantom made of human eye composition, in the presence of GNPs, shows the significance of utilizing the composition of eye in ophthalmic brachytherapy dosimetry Also, defining the eye composition instead of water leads to more accurate calculations of GNPs radiation effects in ophthalmic brachytherapy dosimetry. PACS number: 87.53.Jw, 87.85.Rs, 87.10.Rt PMID:26699318

Radioactive implant migration in patients treated for localized prostate cancer with interstitial brachytherapy.

PubMed

Older, R A; Synder, B; Krupski, T L; Glembocki, D J; Gillenwater, J Y

2001-05-01

In several of the initial patients undergoing brachytherapy at our institution radioactive implants were visible in the thorax on chest radiography. The clinical ramifications of this unanticipated finding were unclear. Thus, we investigated the incidence of brachytherapy seed migration to the chest and whether these seeds were associated with any clinical significance. We retrospectively reviewed the records of all patients who underwent ultrasound or computerized tomography guided brachytherapy of 103palladium seeds from March 1997 to March 1999. This list of patients on brachytherapy was then matched against the radiology computer system to determine those who had undergone chest X-ray after brachytherapy. When the radiology report was unclear regarding brachytherapy seeds, chest x-rays were reviewed by one of us (R. O.) to determine the presence and position of the seeds. Post-brachytherapy chest x-rays were available in 110 of the 183 patients. In 78 cases no brachytherapy seeds were identified. Radioactive implants were identified on chest radiography in 32 patients (29%), including 1 to 5 seeds in 20, 8, 1, 2 and 1, respectively. No patients complained of any change in pulmonary symptoms after brachytherapy. Radioactive implants migrated after brachytherapy for localized prostate cancer in 29% of the patients who underwent post-procedure radiography. There did not appear to be a pattern to the seed distribution. However, while the incidence was not negligible, no patient appeared to have any acute pulmonary symptoms. Therefore, while the migration of radioactive implants to the chest is a real phenomenon, it appears to have no adverse clinical consequences in the early post-procedure period.

In vitro comparative study of vibro-acoustography versus pulse-echo ultrasound in imaging permanent prostate brachytherapy seeds

PubMed Central

Mitri, F.G.; Davis, B.J.; Greenleaf, J.F.; Fatemi, M.

2010-01-01

Background Permanent prostate brachytherapy (PPB) is a common treatment for early stage prostate cancer. While the modern approach using trans-rectal ultrasound guidance has demonstrated excellent outcome, the efficacy of PPB depends on achieving complete radiation dose coverage of the prostate by obtaining a proper radiation source (seed) distribution. Currently, brachytherapy seed placement is guided by trans-rectal ultrasound imaging and fluoroscopy. A significant percentage of seeds are not detected by trans-rectal ultrasound because certain seed orientations are invisible making accurate intra-operative feedback of radiation dosimetry very difficult, if not impossible. Therefore, intra-operative correction of suboptimal seed distributions cannot easily be done with current methods. Vibro-acoustography (VA) is an imaging modality that is capable of imaging solids at any orientation, and the resulting images are speckle free. Objective and methods The purpose of this study is to compare the capabilities of VA and pulse-echo ultrasound in imaging PPB seeds at various angles and show the sensitivity of detection to seed orientation. In the VA experiment, two intersecting ultrasound beams driven at f1 = 3.00 MHz and f2 = 3.020 MHz respectively were focused on the seeds attached to a latex membrane while the amplitude of the acoustic emission produced at the difference frequency 20 kHz was detected by a low frequency hydrophone. Results Finite element simulations and results of experiments conducted under well-controlled conditions in a water tank on a series of seeds indicate that the seeds can be detected at any orientation with VA, whereas pulse-echo ultrasound is very sensitive to the seed orientation. Conclusion It is concluded that vibro-acoustography is superior to pulse-echo ultrasound for detection of PPB seeds. PMID:18538365

Edema and Seed Displacements Affect Intraoperative Permanent Prostate Brachytherapy Dosimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Westendorp, Hendrik, E-mail: r.westendorp@radiotherapiegroep.nl; Nuver, Tonnis T.; Department of Radiation Oncology, Radiotherapiegroep Behandellocatie Deventer, Deventer

Purpose: We sought to identify the intraoperative displacement patterns of seeds and to evaluate the correlation of intraoperative dosimetry with day 30 for permanent prostate brachytherapy. Methods and Materials: We analyzed the data from 699 patients. Intraoperative dosimetry was acquired using transrectal ultrasonography (TRUS) and C-arm cone beam computed tomography (CBCT). Intraoperative dosimetry (minimal dose to 40%-95% of the volume [D{sub 40}-D{sub 95}]) was compared with the day 30 dosimetry for both modalities. An additional edema-compensating comparison was performed for D{sub 90}. Stranded seeds were linked between TRUS and CBCT using an automatic and fast linking procedure. Displacement patterns weremore » analyzed for each seed implantation location. Results: On average, an intraoperative (TRUS to CBCT) D{sub 90} decline of 10.6% ± 7.4% was observed. Intraoperative CBCT D{sub 90} showed a greater correlation (R{sup 2} = 0.33) with respect to Day 30 than did TRUS (R{sup 2} = 0.17). Compensating for edema, the correlation increased to 0.41 for CBCT and 0.38 for TRUS. The mean absolute intraoperative seed displacement was 3.9 ± 2.0 mm. The largest seed displacements were observed near the rectal wall. The central and posterior seeds showed less caudal displacement than lateral and anterior seeds. Seeds that were implanted closer to the base showed more divergence than seeds close to the apex. Conclusions: Intraoperative CBCT D{sub 90} showed a greater correlation with the day 30 dosimetry than intraoperative TRUS. Edema seemed to cause most of the systematic difference between the intraoperative and day 30 dosimetry. Seeds near the rectal wall showed the most displacement, comparing TRUS and CBCT, probably because of TRUS probe–induced prostate deformation.« less

SU-E-T-12: A Comparative Dosimetric Study of Pre and Post Prostate Iodine-125 Permanent Seed Implants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, X; Rahimian, J; Goy, B

Purpose: Post-implant dosimetry has become the gold standard for prostate implant evaluation. The goal of this research is to compare the dosimetry between pre-plan and post-plan in permanent prostate seed implant brachytherapy. Methods: A retrospective study of 91 patients treated with Iodine-125 prostate seed implant between year 2012∼2014 were performed. All plans were created using a VariSeed 8.0 planning system. Pre-plan ultrasound images were acquired using 0.5 cm slice thickness. Post-plan CT images acquired about 1–4 weeks after implant, fused with the preplan ultrasound images. The prostate and urethra contours were generated using the fusion of ultrasound and CT images.more » Iodine-125 seed source activities varied between 0.382 to 0.414 mCi per seed. The loading patterns varied slightly between patients depending on the prostate size. Statistical analysis of pre and post plans for prostate and urethra volumes, V100%, V150% and D90, and urethra D10 were performed and reported. Results: The pre and post implant average prostate size was 36.90cc vs. 38.58cc; V100% was 98.33% vs. 96.89%; V150% was 47.09% vs. 56.95%; D90 was 116.35Gy vs. 116.12Gy, urethra volume was 1.72cc vs. 1.85cc, urethra D10% was 122.0% vs. 135.35%, respectively. There was no statistically significant difference between the pre and post-plan values for D90(p-value=0.43). However, there are significant differences between other parameters most likely due to post surgical edema; prostate size (p-value= 0.00015); V100% (p-value=3.7803E-07); V150% (p-value=1.49E-09); urethra volume (p-value= 2.77E-06); Urethra D10 (p-value=7.37E-11). Conclusion: The post-plan dosimetry using CT image set showed similar D90 dose coverage to the pre-plan using the ultrasound image dataset. The study showed that our prostate seed implants have consistently delivered adequate therapeutic dose to the prostate while sparing urethra. Future studies to correlate dose versus biochemical response using

Relative biologic effectiveness in terms of tumor response of {sup 125}I implants compared with {sup 60}Co gamma rays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lehnert, Shirley; Reniers, Brigitte; Verhaegen, Frank

2005-09-01

Purpose: To measure the relative biologic effectiveness (RBE) for {sup 125}I seeds compared with external beam radiotherapy using a clinically relevant in vivo system. Methods and Materials: Photon emission from a detailed source model was simulated using the Monte Carlo code MCNP4C, sampling from a {sup 125}I spectrum. The mouse RIF-1 tumor was treated with either temporary implant of an {sup 125}I seed or with {sup 60}Co gamma rays. The tumors were always the same size at the initiation of treatment, and the endpoint was growth inhibition. Results: The dose-response curve for both modalities was close to linear and wasmore » independent of the initial {sup 125}I activity (dose rate) for the range investigated. Calculation of the RBE for tumor response requires assigning a unique value for the tumor dose that is not homogenous but depends on the distance from the {sup 125}I source. Because tumor regrowth will depend on the subpopulation of cells that have the greatest probability of survival (i.e., those at the greatest distance from the {sup 125}I source), one approach is to use the dose to this population. On this basis, the RBE for {sup 125}I compared with {sup 60}Co gamma rays is 1.5. If the {sup 125}I dose is computed as the average dose to the tumor, corrected for the dose that is wasted as overkill in the cell population closest to the center of the {sup 125}I seed, the RBE is 1.4. Conclusion: The result, an RBE of 1.4-1.5 is similar to findings obtained by other methods, supporting the validity of this approach to derive an RBE with validity in a clinical context.« less

Source strength verification and quality assurance of preloaded brachytherapy needles using a CMOS flat panel detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Golshan, Maryam, E-mail: maryam.golshan@bccancer.bc.ca; Spadinger, Ingrid; Chng, Nick

2016-06-15

Purpose: Current methods of low dose rate brachytherapy source strength verification for sources preloaded into needles consist of either assaying a small number of seeds from a separate sample belonging to the same lot used to load the needles or performing batch assays of a subset of the preloaded seed trains. Both of these methods are cumbersome and have the limitations inherent to sampling. The purpose of this work was to investigate an alternative approach that uses an image-based, autoradiographic system capable of the rapid and complete assay of all sources without compromising sterility. Methods: The system consists of amore » flat panel image detector, an autoclavable needle holder, and software to analyze the detected signals. The needle holder was designed to maintain a fixed vertical spacing between the needles and the image detector, and to collimate the emissions from each seed. It also provides a sterile barrier between the needles and the imager. The image detector has a sufficiently large image capture area to allow several needles to be analyzed simultaneously.Several tests were performed to assess the accuracy and reproducibility of source strengths obtained using this system. Three different seed models (Oncura 6711 and 9011 {sup 125}I seeds, and IsoAid Advantage {sup 103}Pd seeds) were used in the evaluations. Seeds were loaded into trains with at least 1 cm spacing. Results: Using our system, it was possible to obtain linear calibration curves with coverage factor k = 1 prediction intervals of less than ±2% near the centre of their range for the three source models. The uncertainty budget calculated from a combination of type A and type B estimates of potential sources of error was somewhat larger, yielding (k = 1) combined uncertainties for individual seed readings of 6.2% for {sup 125}I 6711 seeds, 4.7% for {sup 125}I 9011 seeds, and 11.0% for Advantage {sup 103}Pd seeds. Conclusions: This study showed that a flat panel detector dosimetry

Reconstruction of brachytherapy seed positions and orientations from cone-beam CT x-ray projections via a novel iterative forward projection matching method.

PubMed

Pokhrel, Damodar; Murphy, Martin J; Todor, Dorin A; Weiss, Elisabeth; Williamson, Jeffrey F

2011-01-01

To generalize and experimentally validate a novel algorithm for reconstructing the 3D pose (position and orientation) of implanted brachytherapy seeds from a set of a few measured 2D cone-beam CT (CBCT) x-ray projections. The iterative forward projection matching (IFPM) algorithm was generalized to reconstruct the 3D pose, as well as the centroid, of brachytherapy seeds from three to ten measured 2D projections. The gIFPM algorithm finds the set of seed poses that minimizes the sum-of-squared-difference of the pixel-by-pixel intensities between computed and measured autosegmented radiographic projections of the implant. Numerical simulations of clinically realistic brachytherapy seed configurations were performed to demonstrate the proof of principle. An in-house machined brachytherapy phantom, which supports precise specification of seed position and orientation at known values for simulated implant geometries, was used to experimentally validate this algorithm. The phantom was scanned on an ACUITY CBCT digital simulator over a full 660 sinogram projections. Three to ten x-ray images were selected from the full set of CBCT sinogram projections and postprocessed to create binary seed-only images. In the numerical simulations, seed reconstruction position and orientation errors were approximately 0.6 mm and 5 degrees, respectively. The physical phantom measurements demonstrated an absolute positional accuracy of (0.78 +/- 0.57) mm or less. The theta and phi angle errors were found to be (5.7 +/- 4.9) degrees and (6.0 +/- 4.1) degrees, respectively, or less when using three projections; with six projections, results were slightly better. The mean registration error was better than 1 mm/6 degrees compared to the measured seed projections. Each test trial converged in 10-20 iterations with computation time of 12-18 min/iteration on a 1 GHz processor. This work describes a novel, accurate, and completely automatic method for reconstructing seed orientations, as well as

Reconstruction of brachytherapy seed positions and orientations from cone-beam CT x-ray projections via a novel iterative forward projection matching method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pokhrel, Damodar; Murphy, Martin J.; Todor, Dorin A.

2011-01-15

Purpose: To generalize and experimentally validate a novel algorithm for reconstructing the 3D pose (position and orientation) of implanted brachytherapy seeds from a set of a few measured 2D cone-beam CT (CBCT) x-ray projections. Methods: The iterative forward projection matching (IFPM) algorithm was generalized to reconstruct the 3D pose, as well as the centroid, of brachytherapy seeds from three to ten measured 2D projections. The gIFPM algorithm finds the set of seed poses that minimizes the sum-of-squared-difference of the pixel-by-pixel intensities between computed and measured autosegmented radiographic projections of the implant. Numerical simulations of clinically realistic brachytherapy seed configurations weremore » performed to demonstrate the proof of principle. An in-house machined brachytherapy phantom, which supports precise specification of seed position and orientation at known values for simulated implant geometries, was used to experimentally validate this algorithm. The phantom was scanned on an ACUITY CBCT digital simulator over a full 660 sinogram projections. Three to ten x-ray images were selected from the full set of CBCT sinogram projections and postprocessed to create binary seed-only images. Results: In the numerical simulations, seed reconstruction position and orientation errors were approximately 0.6 mm and 5 deg., respectively. The physical phantom measurements demonstrated an absolute positional accuracy of (0.78{+-}0.57) mm or less. The {theta} and {phi} angle errors were found to be (5.7{+-}4.9) deg. and (6.0{+-}4.1) deg., respectively, or less when using three projections; with six projections, results were slightly better. The mean registration error was better than 1 mm/6 deg. compared to the measured seed projections. Each test trial converged in 10-20 iterations with computation time of 12-18 min/iteration on a 1 GHz processor. Conclusions: This work describes a novel, accurate, and completely automatic method for

Clinical application of computed tomography-guided (125)I seed interstitial implantation for head and neck cancer patients with unmanageable cervical lymph node metastases.

PubMed

Huang, Hai; Xu, Shaonian; Li, Fusheng; Du, Zhenguang; Wang, Liang

2016-04-27

To assess clinical application of computed tomography (CT)-guided (125)I seed implantation for patients who cannot endure or unwillingly receive repeated surgery, chemotherapy, or radiotherapy for unmanageable cervical lymph node metastases in head and neck cancer (HNC). Thirty-one consecutive patients received CT-guided (125)I seed implantation between February 2010 and December 2013. To evaluate the clinical efficiency, karnofsky performance score (KPS), numeric rating scale (NRS), and tumor volume at 3-, and 6-month post-implantation were compared with pre-implantation, along with local control rate (LCR), overall survival rate (OSR), and complications at 3, 6 months, 1, and 2 years. The tumor volume was obviously decreased at 3-, and 6-month post-implantation (21.23 ± 8.83 versus 9.19 ± 7.52 cm(2); 21.23 ± 8.83 versus 6.42 ± 9.79 cm(2); P < 0.05) compared with pre-implantation. The NRS was statistically reduced (3.06 ± 1.06 versus 7.77 ± 0.92; 2.39 ± 1.15 versus 7.77 ± 0.92; P < 0.05), while KPS was significantly improved (83.18 ± 5.97 versus 73.60 ± 7.90; 82.86 ± 5.43 versus 73.60 ± 7.90; P < 0.05) postoperatively at 3 and 6 months, respectively. The LCR at 3, 6 months, 1, and 2 years was 96.30, 83.87, 64.51, and 45.16%, respectively. The OSR was 100, 100, 67.74, and 45.16%, respectively. Three cases experienced grade I and two had grade II acute radiation toxicity. CT-guided seed implantation may be feasible and safe for HNC patients whose neck nodes are not manageable by routine strategies with fewer complications, higher LCR, and significant pain relief.

Brachytherapy in early prostate cancer--early experience.

PubMed

Jose, B O; Bailen, J L; Albrink, F H; Steinbock, G S; Cornett, M S; Benson, D C; Schmied, W K; Medley, R N; Spanos, W J; Paris, K J; Koerner, P D; Gatenby, R A; Wilson, D L; Meyer, R

1999-01-01

Use of brachytherapy with radioactive seeds in the management of early prostate cancer is commonly used in the United States. The early experience has been reported from the prostate treatment centers in Seattle for the last 10 years. In this manuscript we are reporting our early experience of 150 radioactive seed implantations in early stage prostate cancer using either Iodine 125 or Palladium 103 seeds. The average age of the patient is 66 years and the median Gleason score is 5.4 with a median PSA of 6. A brief description of the evolution of the treatment of prostate cancer as well as the preparation for the seed implantation using the volume study with ultrasound of the prostate, pubic arch study using CT scan of the pelvis and the complete planning using the treatment planning computers are discussed. We also have described the current technique which is used in our experience based on the Seattle guidelines. We plan a follow-up report with the results of the studies with longer follow-up.

Portal Vein Stenting Combined with Iodine-125 Seeds Endovascular Implantation Followed by Transcatheter Arterial Chemoembolization for Treatment of Hepatocellular Carcinoma Patients with Portal Vein Tumor Thrombus

PubMed Central

Zhou, Tanyang; Zhu, Tongyin; Zhang, Yuelin; Nie, Chunhui; Ai, Jing; Zhou, Guanhui; Zhang, Aibin; Dong, Meng-Jie; Wang, Wei-Lin

2016-01-01

Aim was to assess the therapeutic value of portal vein stenting (PVS) combined with iodine-125 seed (125I seed) strand endovascular implantation followed by transcatheter arterial chemoembolization (TACE) for treating patients with hepatocellular carcinoma (HCC) and portal vein tumor thrombus (PVTT). This was a retrospective study of 34 patients aged 29–81 years, diagnosed HCC with PVTT, and treated with PVS combined with 125I seed strand endovascular implantation followed by TACE between January 2012 and August 2014. Survival, stent patency, technical success rate, complications related to the procedure, and adverse events were recorded. The technical success rate was 100%. No serious procedure-related adverse event was recorded. The median survival was 147 days. The cumulative survival rates and stent patency rates at 90, 180, and 360 days were 94.1%, 61.8%, and 32.4% and 97.1% (33/34), 76.9% (24/34), and 29.4% (10/34), respectively. PVS combined with 125I seed strand endovascular implantation followed by TACE is feasible for patients with HCC and PVTT. It resulted in appropriate survival and stent patency, with no procedure-related adverse effects. PMID:27999793

Dose Constraint for Minimizing Grade 2 Rectal Bleeding Following Brachytherapy Combined With External Beam Radiotherapy for Localized Prostate Cancer: Rectal Dose-Volume Histogram Analysis of 457 Patients

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shiraishi, Yutaka; Yorozu, Atsunori; Ohashi, Toshio, E-mail: ohashi@rad.med.keio.ac.jp

2011-11-01

Purpose: To determine the rectal tolerance to Grade 2 rectal bleeding after I-125 seed brachytherapy combined with external beam radiotherapy (EBRT), based on the rectal dose-volume histogram. Methods and Materials: A total of 458 consecutive patients with stages T1 to T3 prostate cancer received combined modality treatment consisting of I-125 seed implantation followed by EBRT to the prostate and seminal vesicles. The prescribed doses of brachytherapy and EBRT were 100 Gy and 45 Gy in 25 fractions, respectively. The rectal dosimetric factors were analyzed for rectal volumes receiving >100 Gy and >150 Gy (R100 and R150) during brachytherapy and formore » rectal volumes receiving >30 Gy to 40 Gy (V30-V40) during EBRT therapy in 373 patients for whom datasets were available. The patients were followed from 21 to 72 months (median, 45 months) after the I-125 seed implantation. Results: Forty-four patients (9.7%) developed Grade 2 rectal bleeding. On multivariate analysis, age (p = 0.014), R100 (p = 0.002), and V30 (p = 0.001) were identified as risk factors for Grade 2 rectal bleeding. The rectal bleeding rate increased as the R100 increased: 5.0% (2/40 patients) for 0 ml; 7.5% (20/267 patients) for >0 to 0.5 ml; 11.0% (11/100 patients) for >0.5 to 1 ml; 17.9% (5/28 patients) for >1 to 1.5 ml; and 27.3% (6/22 patients) for >1.5 ml (p = 0.014). Grade 2 rectal bleeding developed in 6.4% (12/188) of patients with a V30 {<=}35% and in 14.1% (26/185) of patients with a V30 >35% (p = 0.02). When these dose-volume parameters were considered in combination, the Grade 2 rectal bleeding rate was 4.2% (5/120 patients) for a R100 {<=}0.5 ml and a V30 {<=}35%, whereas it was 22.4% (13/58 patients) for R100 of >0.5 ml and V30 of >35%. Conclusion: The risk of rectal bleeding was found to be significantly volume-dependent in patients with prostate cancer who received combined modality treatment. Rectal dose-volume analysis is a practical method for predicting the risk of

Prostate-specific antigen density is predictive of outcome in suboptimal prostate seed brachytherapy.

PubMed

Benzaquen, David; Delouya, Guila; Ménard, Cynthia; Barkati, Maroie; Taussky, Daniel

In prostate seed brachytherapy, a D 90 of <130 Gy is an accepted predictive factor for biochemical failure (BF). We studied whether there is a subpopulation that does not need additional treatment after a suboptimal permanent seed brachytherapy implantation. A total of 486 patients who had either BF or a minimum followup of 48 months without BF were identified. BF was defined according to the Phoenix definition (nadir prostate-specific antigen + 2). Univariate and multivariate analyses were performed, adjusting for known prognostic factors such as D 90 and prostate-specific antigen density (PSAD) of ≥0.15 ng/mL/cm 3 , to evaluate their ability to predict BF. Median followup for patients without BF was 72 months (interquartile range 56-96). BF-free recurrence rate at 5 years was 95% and at 8 years 88%. In univariate analysis, PSAD and cancer of the prostate risk assessment score were predictive of BF. On multivariate analysis, none of the factors remained significant. The best prognosis had patients with a low PSAD (<0.15 ng/mL/cm 3 ) and an optimal implant at 30 days after implantation (as defined by D 90  ≥ 130 Gy) compared to patients with both factors unfavorable (p = 0.006). A favorable PSAD was associate with a good prognosis, independently of the D 90 (<130 Gy vs. ≥130 Gy, p = 0.7). Patients with a PSAD of <0.15 ng/mL/cm 3 have little risk of BF, even in the case of a suboptimal implant. These results need to be validated in other patients' cohorts. Copyright © 2016 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

[Valorisation of brachytherapy and medico-economic considerations].

PubMed

Pommier, P; Morelle, M; Millet-Lagarde, F; Peiffert, D; Gomez, F; Perrier, L

2013-04-01

Economic data in the literature for brachytherapy are still sparse and heterogeneous, with few controlled prospective studies and a perspective most often limited to those of the provider (health insurances). Moreover, these observation and conclusions are difficult to generalize in France. The prospective health economic studies performed in France in the framework of a national program to sustain innovative and costly therapies (STIC program) launched by the French cancer national institute are therefore of most importance. With the exception of prostate brachytherapy with permanent seeds, the valorisation of the brachytherapy activity by the French national health insurance does not take into account the degree of complexity and the real costs supported by health institutions (i.e. no specific valorisation for 3D image-based treatment planning and dose optimization and for the use of pulsed dose rate brachytherapy). Copyright © 2013 Société française de radiothérapie oncologique (SFRO). Published by Elsevier SAS. All rights reserved.

Dose escalation in permanent brachytherapy for prostate cancer: dosimetric and biological considerations

NASA Astrophysics Data System (ADS)

Li, X. Allen; Wang, Jian Z.; Stewart, Robert D.; Di Biase, Steven J.

2003-09-01

No prospective dose escalation study for prostate brachytherapy (PB) with permanent implants has been reported. In this work, we have performed a dosimetric and biological analysis to explore the implications of dose escalation in PB using 125I and 103Pd implants. The concept of equivalent uniform dose (EUD), proposed originally for external-beam radiotherapy (EBRT), is applied to low dose rate brachytherapy. For a given 125I or 103Pd PB, the EUD for tumour that corresponds to a dose distribution delivered by EBRT is calculated based on the linear quadratic model. The EUD calculation is based on the dose volume histogram (DVH) obtained retrospectively from representative actual patient data. Tumour control probabilities (TCPs) are also determined in order to compare the relative effectiveness of different dose levels. The EUD for normal tissue is computed using the Lyman model. A commercial inverse treatment planning algorithm is used to investigate the feasibility of escalating the dose to prostate with acceptable dose increases in the rectum and urethra. The dosimetric calculation is performed for five representative patients with different prostate sizes. A series of PB dose levels are considered for each patient using 125I and 103Pd seeds. It is found that the PB prescribed doses (minimum peripheral dose) that give an equivalent EBRT dose of 64.8, 70.2, 75.6 and 81 Gy with a fraction size of 1.8 Gy are 129, 139, 150 and 161 Gy for 125I and 103, 112, 122 and 132 Gy for 103Pd implants, respectively. Estimates of the EUD and TCP for a series of possible prescribed dose levels (e.g., 145, 160, 170 and 180 Gy for 125I and 125, 135, 145 and 155 for 103Pd implants) are tabulated. The EUD calculation was found to depend strongly on DVHs and radiobiological parameters. The dosimetric calculations suggest that the dose to prostate can be escalated without a substantial increase in both rectal and urethral dose. For example, increasing the PB prescribed dose from 145 to

Dosimetric and Late Radiation Toxicity Comparison Between Iodine-125 Brachytherapy and Stereotactic Radiation Therapy for Juxtapapillary Choroidal Melanoma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krema, Hatem, E-mail: htmkrm19@yahoo.com; Heydarian, Mostafa; Beiki-Ardakani, Akbar

2013-07-01

Purpose: To compare the dose distributions and late radiation toxicities for {sup 125}I brachytherapy (IBT) and stereotactic radiation therapy (SRT) in the treatment of juxtapapillary choroidal melanoma. Methods: Ninety-four consecutive patients with juxtapapillary melanoma were reviewed: 30 have been treated with IBT and 64 with SRT. Iodine-125 brachytherapy cases were modeled with plaque simulator software for dosimetric analysis. The SRT dosimetric data were obtained from the Radionics XKnife RT3 software. Mean doses at predetermined intraocular points were calculated. Kaplan-Meier estimates determined the actuarial rates of late toxicities, and the log–rank test compared the estimates. Results: The median follow-up was 46more » months in both cohorts. The 2 cohorts were balanced with respect to pretreatment clinical and tumor characteristics. Comparisons of radiation toxicity rates between the IBT and SRT cohorts yielded actuarial rates at 50 months for cataracts of 62% and 75% (P=.1), for neovascular glaucoma 8% and 47% (P=.002), for radiation retinopathy 59% and 89% (P=.0001), and for radiation papillopathy 39% and 74% (P=.003), respectively. Dosimetric comparisons between the IBT and SRT cohorts yielded mean doses of 12.8 and 14.1 Gy (P=.56) for the lens center, 17.6 and 19.7 Gy (P=.44) for the lens posterior pole, 13.9 and 10.8 Gy (P=.30) for the ciliary body, 61.9 and 69.7 Gy (P=.03) for optic disc center, and 48.9 and 60.1 Gy (P<.0001) for retina at 5-mm distance from tumor margin, respectively. Conclusions: Late radiation-induced toxicities were greater with SRT, which is secondary to the high-dose exposure inherent to the technique as compared with IBT. When technically feasible, IBT is preferred to treat juxtapapillary choroidal melanoma.« less

Computational and Experimental Evaluations of a Novel Thermo-Brachytherapy Seed for Treatment of Solid Tumors

NASA Astrophysics Data System (ADS)

Warrell, Gregory R.

Hyperthermia has long been known as a radiation therapy sensitizer of high potential; however successful delivery of this modality and integrating it with radiation have often proved technically difficult. We present the dual-modality thermobrachytherapy (TB) seed, based on the ubiquitous low dose-rate (LDR) brachytherapy permanent implant, as a simple and effective combination of hyperthermia and radiation therapy. Heat is generated from a ferromagnetic or ferrimagnetic core within the seed, which produces Joule heating by eddy currents. A strategically-selected Curie temperature provides thermal self-regulation. In order to obtain a uniform and sufficiently high temperature distribution, additional hyperthermia-only (HT-only) seeds are proposed to be used in vacant spots within the needles used to implant the TB seeds; this permits a high seed density without the use of additional needles. Experimental and computational studies were done both to optimize the design of the TB and HT-only seeds and to quantitatively assess their ability to heat and irradiate defined, patient-specific targets. Experiments were performed with seed-sized ferromagnetic samples in tissue-mimicking phantoms heated by an industrial induction heater. The magnetic and thermal properties of the seeds were studied computationally in the finite element analysis (FEA) solver COMSOL Multiphysics, modelling realistic patient-specific seed distributions. These distributions were derived from LDR permanent prostate implants previously conducted at our institution; various modifications of the seeds' design were studied. The calculated temperature distributions were analyzed by generating temperature-volume histograms, which were used to quantify coverage and temperature homogeneity for a range of blood perfusion rates, as well as for a range of seed Curie temperatures and thermal power production rates. The impact of the interseed attenuation and scatter (ISA) effect on radiation dose distributions

TU-AB-BRC-08: Egs-brachy, a Fast and Versatile Monte Carlo Code for Brachytherapy Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chamberland, M; Taylor, R; Rogers, D

2016-06-15

Purpose: To introduce egs-brachy, a new, fast, and versatile Monte Carlo code for brachytherapy applications. Methods: egs-brachy is an EGSnrc user-code based on the EGSnrc C++ class library (egs++). Complex phantom, applicator, and source model geometries are built using the egs++ geometry module. egs-brachy uses a tracklength estimator to score collision kerma in voxels. Interaction, spectrum, energy fluence, and phase space scoring are also implemented. Phase space sources and particle recycling may be used to improve simulation efficiency. HDR treatments (e.g. stepping source through dwell positions) can be simulated. Standard brachytherapy seeds, as well as electron and miniature x-ray tubemore » sources are fully modelled. Variance reduction techniques for electron source simulations are implemented (Bremsstrahlung cross section enhancement, uniform Bremsstrahlung splitting, and Russian Roulette). TG-43 parameters of seeds are computed and compared to published values. Example simulations of various treatments are carried out on a single 2.5 GHz Intel Xeon E5-2680 v3 processor core. Results: TG-43 parameters calculated with egs-brachy show excellent agreement with published values. Using a phase space source, 2% average statistical uncertainty in the PTV ((2mm){sup 3} voxels) can be achieved in 10 s for 100 {sup 125}I or {sup 103}Pd seeds in a 36.2 cm{sup 3} prostate PTV, 31 s for 64 {sup 103}Pd seeds in a 64 cm{sup 3} breast PTV, and 56 s for a miniature x-ray tube in a 27 cm{sup 3} breast PTV. Comparable uncertainty is reached in 12 s in a (1 mm){sup 3} water voxel 5 mm away from a COMS 16mm eye plaque with 13 {sup 103}Pd seeds. Conclusion: The accuracy of egs-brachy has been demonstrated through benchmarking calculations. Calculation times are sufficiently fast to allow full MC simulations for routine treatment planning for diverse brachytherapy treatments (LDR, HDR, miniature x-ray tube). egs-brachy will be available as free and open-source software to

Methods for prostate stabilization during transperineal LDR brachytherapy.

PubMed

Podder, Tarun; Sherman, Jason; Rubens, Deborah; Messing, Edward; Strang, John; Ng, Wan-Sing; Yu, Yan

2008-03-21

In traditional prostate brachytherapy procedures for a low-dose-rate (LDR) radiation seed implant, stabilizing needles are first inserted to provide some rigidity and support to the prostate. Ideally this will provide better seed placement and an overall improved treatment. However, there is much speculation regarding the effectiveness of using regular brachytherapy needles as stabilizers. In this study, we explored the efficacy of two types of needle geometries (regular brachytherapy needle and hooked needle) and several clinically feasible configurations of the stabilization needles. To understand and assess the prostate movement during seed implantation, we collected in vivo data from patients during actual brachytherapy procedures. In vitro experimentation with tissue-equivalent phantoms allowed us to further understand the mechanics behind prostate stabilization. We observed superior stabilization with the hooked needles compared to the regular brachytherapy needles (more than 40% in bilateral parallel needle configuration). Prostate movement was also reduced significantly when regular brachytherapy needles were in an angulated configuration as compared to the parallel configuration (more than 60%). When the hooked needles were angulated for stabilization, further reduction in prostate displacement was observed. In general, for convenience of dosimetric planning and to avoid needle collision, all needles are desired to be in a parallel configuration. In this configuration, hooked needles provide improved stabilization of the prostate. On the other hand, both regular and hooked needles appear to be equally effective in reducing prostate movement when they are in angulated configurations, which will be useful in seed implantation using a robotic system. We have developed nonlinear spring-damper model for the prostate movement which can be used for adapting dosimetric planning during brachytherapy as well as for developing more realistic haptic devices and

Praseodymium-142 glass seeds for the brachytherapy of prostate cancer

NASA Astrophysics Data System (ADS)

Jung, Jae Won

A beta-emitting glass seed was proposed for the brachytherapy treatment of prostate cancer. Criteria for seed design were derived and several beta-emitting nuclides were examined for suitability. 142Pr was selected as the isotope of choice. Seeds 0.08 cm in diameter and 0.9 cm long were manufactured for testing. The seeds were activated in the Texas A&M University research reactor. The activity produced was as expected when considering the meta-stable state and epi-thermal neutron flux. The MCNP5 Monte Carlo code was used to calculate the quantitative dosimetric parameters suggested in the American Association of Physicists in Medicine (AAPM) TG-43/60. The Monte Carlo calculation results were compared with those from a dose point kernel code. The dose profiles agree well with each other. The gamma dose of 142Pr was evaluated. The gamma dose is 0.3 Gy at 1.0 cm with initial activity of 5.95 mCi and is insignificant to other organs. Measurements were performed to assess the 2-dimensional axial dose distributions using Gafchromic radiochromic film. The radiochromic film was calibrated using an X-ray machine calibrated against a National Institute of Standards and Technology (NIST) traceable ion chamber. A calibration curve was derived using a least squares fit of a second order polynomial. The measured dose distribution agrees well with results from the Monte Carlo simulation. The dose was 130.8 Gy at 6 mm from the seed center with initial activity of 5.95 mCi. AAPM TG-43/60 parameters were determined. The reference dose rate for 2 mm and 6 mm were 0.67 and 0.02 cGy/s/mCi, respectively. The geometry function, radial dose function and anisotropy function were generated.

Reduced dose to urethra and rectum with the use of variable needle spacing in prostate brachytherapy: a potential role for robotic technology.

PubMed

Vyas, Shilpa; Le, Yi; Zhang, Zhe; Armour, Woody; Song, Daniel Y

2015-08-01

Several robotic delivery systems for prostate brachytherapy are under development or in pre-clinical testing. One of the features of robotic brachytherapy is the ability to vary spacing of needles at non-fixed intervals. This feature may play an important role in prostate brachytherapy, which is traditionally template-based with fixed needle spacing of 0.5 cm. We sought to quantify potential reductions in the dose to urethra and rectum by utilizing variable needle spacing, as compared to fixed needle spacing. Transrectal ultrasound images from 10 patients were used by 3 experienced planners to create 120 treatment plans. Each planner created 4 plan variations per patient with respect to needle positions: (125)I fixed spacing, (125)I variable spacing, (103)Pd fixed spacing, and (103)Pd variable spacing. The primary planning objective was to achieve a prostate V100 of 100% while minimizing dose to urethra and rectum. All plans met the objective of achieving prostate V100 of 100%. Combined results for all plans show statistically significant improvements in all assessed dosimetric variables for urethra (Umax, Umean, D30, D5) and rectum (Rmax, Rmean, RV100) when using variable spacing. The dose reductions for mean and maximum urethra dose using variable spacing had p values of 0.011 and 0.024 with (103)Pd, and 0.007 and 0.029 with (125)I plans. Similarly dose reductions for mean and maximum rectal dose using variable spacing had p values of 0.007 and 0.052 with (103)Pd, and 0.012 and 0.037 with (125)I plans. The variable needle spacing achievable by the use of robotics in prostate brachytherapy allows for reductions in both urethral and rectal planned doses while maintaining prostate dose coverage. Such dosimetric advantages have the potential in translating to significant clinical benefits with the use of robotic brachytherapy.

Clinical application and validation of an iterative forward projection matching algorithm for permanent brachytherapy seed localization from conebeam-CT x-ray projections.

PubMed

Pokhrel, Damodar; Murphy, Martin J; Todor, Dorin A; Weiss, Elisabeth; Williamson, Jeffrey F

2010-09-01

To experimentally validate a new algorithm for reconstructing the 3D positions of implanted brachytherapy seeds from postoperatively acquired 2D conebeam-CT (CBCT) projection images. The iterative forward projection matching (IFPM) algorithm finds the 3D seed geometry that minimizes the sum of the squared intensity differences between computed projections of an initial estimate of the seed configuration and radiographic projections of the implant. In-house machined phantoms, containing arrays of 12 and 72 seeds, respectively, are used to validate this method. Also, four 103Pd postimplant patients are scanned using an ACUITY digital simulator. Three to ten x-ray images are selected from the CBCT projection set and processed to create binary seed-only images. To quantify IFPM accuracy, the reconstructed seed positions are forward projected and overlaid on the measured seed images to find the nearest-neighbor distance between measured and computed seed positions for each image pair. Also, the estimated 3D seed coordinates are compared to known seed positions in the phantom and clinically obtained VariSeed planning coordinates for the patient data. For the phantom study, seed localization error is (0.58 +/- 0.33) mm. For all four patient cases, the mean registration error is better than 1 mm while compared against the measured seed projections. IFPM converges in 20-28 iterations, with a computation time of about 1.9-2.8 min/ iteration on a 1 GHz processor. The IFPM algorithm avoids the need to match corresponding seeds in each projection as required by standard back-projection methods. The authors' results demonstrate approximately 1 mm accuracy in reconstructing the 3D positions of brachytherapy seeds from the measured 2D projections. This algorithm also successfully localizes overlapping clustered and highly migrated seeds in the implant.

Clinical application and validation of an iterative forward projection matching algorithm for permanent brachytherapy seed localization from conebeam-CT x-ray projections

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pokhrel, Damodar; Murphy, Martin J.; Todor, Dorin A.

2010-09-15

Purpose: To experimentally validate a new algorithm for reconstructing the 3D positions of implanted brachytherapy seeds from postoperatively acquired 2D conebeam-CT (CBCT) projection images. Methods: The iterative forward projection matching (IFPM) algorithm finds the 3D seed geometry that minimizes the sum of the squared intensity differences between computed projections of an initial estimate of the seed configuration and radiographic projections of the implant. In-house machined phantoms, containing arrays of 12 and 72 seeds, respectively, are used to validate this method. Also, four {sup 103}Pd postimplant patients are scanned using an ACUITY digital simulator. Three to ten x-ray images are selectedmore » from the CBCT projection set and processed to create binary seed-only images. To quantify IFPM accuracy, the reconstructed seed positions are forward projected and overlaid on the measured seed images to find the nearest-neighbor distance between measured and computed seed positions for each image pair. Also, the estimated 3D seed coordinates are compared to known seed positions in the phantom and clinically obtained VariSeed planning coordinates for the patient data. Results: For the phantom study, seed localization error is (0.58{+-}0.33) mm. For all four patient cases, the mean registration error is better than 1 mm while compared against the measured seed projections. IFPM converges in 20-28 iterations, with a computation time of about 1.9-2.8 min/iteration on a 1 GHz processor. Conclusions: The IFPM algorithm avoids the need to match corresponding seeds in each projection as required by standard back-projection methods. The authors' results demonstrate {approx}1 mm accuracy in reconstructing the 3D positions of brachytherapy seeds from the measured 2D projections. This algorithm also successfully localizes overlapping clustered and highly migrated seeds in the implant.« less

WE-A-17A-09: Exploiting Electromagnetic Technologies for Real-Time Seed Drop Position Validation in Permanent Implant Brachytherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Racine, E; Hautvast, G; Binnekamp, D

Purpose: To report on preliminary results validating the performance of a specially designed LDR brachytherapy needle prototype possessing both electromagnetic (EM) tracking and seed drop detection abilities. Methods: An EM hollow needle prototype has been designed and constructed in collaboration with research partner Philips Healthcare. The needle possesses conventional 3D tracking capabilities, along with a novel seed drop detection mechanism exploiting local changes of electromagnetic properties generated by the passage of seeds in the needle's embedded sensor coils. These two capabilities are exploited by proprietary engineering and signal processing techniques to generate seed drop position estimates in real-time treatment delivery.more » The electromagnetic tracking system (EMTS) used for the experiment is the NDI Aurora Planar Field Generator. The experiment consisted of dropping a total of 35 seeds in a prismatic agarose phantom, and comparing the 3D seed drop positions of the EMTS to those obtained by an image analysis of subsequent micro-CT scans. Drop position error computations and statistical analysis were performed after a 3D registration of the two seed distributions. Results: Of the 35 seeds dropped in the phantom, 32 were properly detected by the needle prototype. Absolute drop position errors among the detected seeds ranged from 0.5 to 4.8 mm with mean and standard deviation values of 1.6 and 0.9 mm, respectively. Error measurements also include undesirable and uncontrollable effects such as seed motion upon deposition. The true accuracy performance of the needle prototype is therefore underestimated. Conclusion: This preliminary study demonstrates the potential benefits of EM technologies in detecting the passage of seeds in a hollow needle as a means of generating drop position estimates in real-time treatment delivery. Such tools could therefore represent a potentially interesting addition to existing brachytherapy protocols for rapid

SU-G-IeP1-01: A Novel MRI Post-Processing Algorithm for Visualization of the Prostate LDR Brachytherapy Seeds and Calcifications Based On B0 Field Inhomogeneity Correction and Hough Transform

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nosrati, R; Sunnybrook Health Sciences Centre, Toronto, Ontario; Soliman, A

Purpose: This study aims at developing an MRI-only workflow for post-implant dosimetry of the prostate LDR brachytherapy seeds. The specific goal here is to develop a post-processing algorithm to produce positive contrast for the seeds and prostatic calcifications and differentiate between them on MR images. Methods: An agar-based phantom incorporating four dummy seeds (I-125) and five calcifications of different sizes (from sheep cortical bone) was constructed. Seeds were placed arbitrarily in the coronal plane. The phantom was scanned with 3T Philips Achieva MR scanner using an 8-channel head coil array. Multi-echo turbo spin echo (ME-TSE) and multi-echo gradient recalled echomore » (ME-GRE) sequences were acquired. Due to minimal susceptibility artifacts around seeds, ME-GRE sequence (flip angle=15; TR/TE=20/2.3/2.3; resolution=0.7×0.7×2mm3) was further processed.The induced field inhomogeneity due to the presence of titaniumencapsulated seeds was corrected using a B0 field map. B0 map was calculated using the ME-GRE sequence by calculating the phase difference at two different echo times. Initially, the product of the first echo and B0 map was calculated. The features corresponding to the seeds were then extracted in three steps: 1) the edge pixels were isolated using “Prewitt” operator; 2) the Hough transform was employed to detect ellipses approximately matching the dimensions of the seeds and 3) at the position and orientation of the detected ellipses an ellipse was drawn on the B0-corrected image. Results: The proposed B0-correction process produced positive contrast for the seeds and calcifications. The Hough transform based on Prewitt edge operator successfully identified all the seeds according to their ellipsoidal shape and dimensions in the edge image. Conclusion: The proposed post-processing algorithm successfully visualized the seeds and calcifications with positive contrast and differentiates between them according to their shapes. Further

Novel Parameter Predicting Grade 2 Rectal Bleeding After Iodine-125 Prostate Brachytherapy Combined With External Beam Radiation Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shiraishi, Yutaka, E-mail: shiraishi@rad.med.keio.ac.jp; Hanada, Takashi; Ohashi, Toshio

2013-09-01

Purpose: To propose a novel parameter predicting rectal bleeding on the basis of generalized equivalent uniform doses (gEUD) after {sup 125}I prostate brachytherapy combined with external beam radiation therapy and to assess the predictive value of this parameter. Methods and Materials: To account for differences among radiation treatment modalities and fractionation schedules, rectal dose–volume histograms (DVHs) of 369 patients with localized prostate cancer undergoing combined therapy retrieved from corresponding treatment planning systems were converted to equivalent dose-based DVHs. The gEUDs for the rectum were calculated from these converted DVHs. The total gEUD (gEUD{sub sum}) was determined by a summation ofmore » the brachytherapy and external-beam radiation therapy components. Results: Thirty-eight patients (10.3%) developed grade 2+ rectal bleeding. The grade 2+ rectal bleeding rate increased as the gEUD{sub sum} increased: 2.0% (2 of 102 patients) for <70 Gy, 10.3% (15 of 145 patients) for 70-80 Gy, 15.8% (12 of 76 patients) for 80-90 Gy, and 19.6% (9 of 46 patients) for >90 Gy (P=.002). Multivariate analysis identified age (P=.024) and gEUD{sub sum} (P=.000) as risk factors for grade 2+ rectal bleeding. Conclusions: Our results demonstrate gEUD to be a potential predictive factor for grade 2+ late rectal bleeding after combined therapy for prostate cancer.« less

MRI/TRUS data fusion for prostate brachytherapy. Preliminary results.

PubMed

Reynier, Christophe; Troccaz, Jocelyne; Fourneret, Philippe; Dusserre, André; Gay-Jeune, Cécile; Descotes, Jean-Luc; Bolla, Michel; Giraud, Jean-Yves

2004-06-01

Prostate brachytherapy involves implanting radioactive seeds (I125 for instance) permanently in the gland for the treatment of localized prostate cancers, e.g., cT1c-T2a N0 M0 with good prognostic factors. Treatment planning and seed implanting are most often based on the intensive use of transrectal ultrasound (TRUS) imaging. This is not easy because prostate visualization is difficult in this imaging modality particularly as regards the apex of the gland and from an intra- and interobserver variability standpoint. Radioactive seeds are implanted inside open interventional MR machines in some centers. Since MRI was shown to be sensitive and specific for prostate imaging whilst open MR is prohibitive for most centers and makes surgical procedures very complex, this work suggests bringing the MR virtually in the operating room with MRI/TRUS data fusion. This involves providing the physician with bi-modality images (TRUS plus MRI) intended to improve treatment planning from the data registration stage. The paper describes the method developed and implemented in the PROCUR system. Results are reported for a phantom and first series of patients. Phantom experiments helped characterize the accuracy of the process. Patient experiments have shown that using MRI data linked with TRUS data improves TRUS image segmentation especially regarding the apex and base of the prostate. This may significantly modify prostate volume definition and have an impact on treatment planning.

Dosimetric characterization and output verification for conical brachytherapy surface applicators. Part I. Electronic brachytherapy source

PubMed Central

Fulkerson, Regina K.; Micka, John A.; DeWerd, Larry A.

2014-01-01

Purpose: Historically, treatment of malignant surface lesions has been achieved with linear accelerator based electron beams or superficial x-ray beams. Recent developments in the field of brachytherapy now allow for the treatment of surface lesions with specialized conical applicators placed directly on the lesion. Applicators are available for use with high dose rate (HDR) 192Ir sources, as well as electronic brachytherapy sources. Part I of this paper will discuss the applicators used with electronic brachytherapy sources; Part II will discuss those used with HDR 192Ir sources. Although the use of these applicators has gained in popularity, the dosimetric characteristics including depth dose and surface dose distributions have not been independently verified. Additionally, there is no recognized method of output verification for quality assurance procedures with applicators like these. Existing dosimetry protocols available from the AAPM bookend the cross-over characteristics of a traditional brachytherapy source (as described by Task Group 43) being implemented as a low-energy superficial x-ray beam (as described by Task Group 61) as observed with the surface applicators of interest. Methods: This work aims to create a cohesive method of output verification that can be used to determine the dose at the treatment surface as part of a quality assurance/commissioning process for surface applicators used with HDR electronic brachytherapy sources (Part I) and 192Ir sources (Part II). Air-kerma rate measurements for the electronic brachytherapy sources were completed with an Attix Free-Air Chamber, as well as several models of small-volume ionization chambers to obtain an air-kerma rate at the treatment surface for each applicator. Correction factors were calculated using MCNP5 and EGSnrc Monte Carlo codes in order to determine an applicator-specific absorbed dose to water at the treatment surface from the measured air-kerma rate. Additionally, relative dose

I-125 ROPES eye plaque dosimetry: validation of a commercial 3D ophthalmic brachytherapy treatment planning system and independent dose calculation software with GafChromic® EBT3 films.

PubMed

Poder, Joel; Corde, Stéphanie

2013-12-01

The purpose of this study was to measure the dose distributions for different Radiation Oncology Physics and Engineering Services, Australia (ROPES) type eye plaques loaded with I-125 (model 6711) seeds using GafChromic(®) EBT3 films, in order to verify the dose distributions in the Plaque Simulator™ (PS) ophthalmic 3D treatment planning system. The brachytherapy module of RADCALC(®) was used to independently check the dose distributions calculated by PS. Correction factors were derived from the measured data to be used in PS to account for the effect of the stainless steel ROPES plaque backing on the 3D dose distribution. Using GafChromic(®) EBT3 films inserted in a specially designed Solid Water™ eye ball phantom, dose distributions were measured three-dimensionally both along and perpendicular to I-125 (model 6711) loaded ROPES eye plaque's central axis (CAX) with 2 mm depth increments. Each measurement was performed in full scatter conditions both with and without the stainless steel plaque backing attached to the eye plaque, to assess its effect on the dose distributions. Results were compared to the dose distributions calculated by Plaque Simulator™ and checked independently with RADCALC(®). The EBT3 film measurements without the stainless steel backing were found to agree with PS and RADCALC(®) to within 2% and 4%, respectively, on the plaque CAX. Also, RADCALC(®) was found to agree with PS to within 2%. The CAX depth doses measured using EBT3 film with the stainless steel backing were observed to result in a 4% decrease relative to when the backing was not present. Within experimental uncertainty, the 4% decrease was found to be constant with depth and independent of plaque size. Using a constant dose correction factor of T = 0.96 in PS, where the calculated dose for the full water scattering medium is reduced by 4% in every voxel in the dose grid, the effect of the plaque backing was accurately modeled in the planning system. Off-axis profiles

Fast radioactive seed localization in intraoperative cone beam CT for low-dose-rate prostate brachytherapy

NASA Astrophysics Data System (ADS)

Hu, Yu-chi; Xiong, Jian-ping; Cohan, Gilad; Zaider, Marco; Mageras, Gig; Zelefsky, Michael

2013-03-01

A fast knowledge-based radioactive seed localization method for brachytherapy was developed to automatically localize radioactive seeds in an intraoperative volumetric cone beam CT (CBCT) so that corrections, if needed, can be made during prostate implant surgery. A transrectal ultrasound (TRUS) scan is acquired for intraoperative treatment planning. Planned seed positions are transferred to intraoperative CBCT following TRUS-to-CBCT registration using a reference CBCT scan of the TRUS probe as a template, in which the probe and its external fiducial markers are pre-segmented and their positions in TRUS are known. The transferred planned seeds and probe serve as an atlas to reduce the search space in CBCT. Candidate seed voxels are identified based on image intensity. Regions are grown from candidate voxels and overlay regions are merged. Region volume and intensity variance is checked against known seed volume and intensity profile. Regions meeting the above criteria are flagged as detected seeds; otherwise they are flagged as likely seeds and sorted by a score that is based on volume, intensity profile and distance to the closest planned seed. A graphical interface allows users to review and accept or reject likely seeds. Likely seeds with approximately twice the seed volume are automatically split. Five clinical cases are tested. Without any manual correction in seed detection, the method performed the localization in 5 seconds (excluding registration time) for a CBCT scan with 512×512×192 voxels. The average precision rate per case is 99% and the recall rate is 96% for a total of 416 seeds. All false negative seeds are found with 15 in likely seeds and 1 included in a detected seed. With the new method, updating of calculations of dose distribution during the procedure is possible and thus facilitating evaluation and improvement of treatment quality.

[Orgasm after curietherapy with permanent iodine-125 radioimplants for localized prostate cancer].

PubMed

Delaunay, B; Delannes, M; Salloum, A; Delavierre, D; Wagner, F; Jonca, F; Thoulouzan, M; Plante, P; Bachaud, J-M; Soulie, M; Huyghe, E

2011-12-01

Orgasm is a domain of male sexuality that remains underreported in literature. Our aim was to realize the first detailed analysis of orgasm in patients treated by 125 I permanent prostate brachytherapy for localized prostate cancer. In a series of 270 sexually active men treated by prostate brachytherapy (125I permanent implantation), 241 (89%), mean age of 65 (43-80), participated in a mailed survey about sexual function after a mean time of 36 months (9-70). Erectile and ejaculatory functions and orgasm were explored using a mailed questionnaire. Two questions focused on orgasm. The first was about quality of orgasm (fast/intense/late, difficult/weak/absent) and the second about the presence of painful orgasm and its frequency (always/sometimes/often). After prostate brachytherapy, 81.3% of sexually active men conserved ejaculation and 90% orgasm. There was a significant deterioration of the quality of orgasm (P=0.0001). More than 50% of the patients had an altered orgasm (weak, difficult, absent) after brachytherapy, vs 16% before implantation (P=0.001). Men with a diminished ejaculation volume often had a weak/difficult orgasm (P=0.007). Neoadjuvant hormonal therapy did not seem to impact the quality of orgasm or the frequency of painful ejaculation. Patients who had an IIEF-5 score higher than 12 had frequently intense orgasm (26.7% vs 2.7%; P<0.001) after brachytherapy. Sixty patients (30.3%) experienced often/sometimes painful ejaculation 12.9% (n=31) before implantation (P=0.0001). Most of the patients treated by prostate brachytherapy conserved orgasm after treatment. However, most of the patients described a deterioration of the quality of orgasm. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

Radio-guided occult lesion localisation using iodine 125 Seeds “ROLLIS” to guide surgical removal of an impalpable posterior chest wall melanoma metastasis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dissanayake, Shashini; Dissanayake, Deepthi; Taylor, Donna B

Cancer screening and surveillance programmes and the use of sophisticated imaging tools such as positron emission tomography-computed tomography (PET-CT) have increased the detection of impalpable lesions requiring imaging guidance for excision. A new technique involves intra-lesional insertion of a low-activity iodine-125 ({sup 125}I) seed and detection of the radioactive signal in theatre using a hand-held gamma probe to guide surgery. Whilst several studies describe using this method to guide the removal of impalpable breast lesions, only a handful of publications report its use to guide excision of lesions outside the breast. We describe a case in which radio-guided occult lesionmore » localisation using an iodine 125 seed was used to guide excision of an impalpable posterior chest wall metastasis detected on PET-CT.« less

Regulation of Autophagy Via PERK-eIF2α Effectively Relieve the Radiation Myelitis Induced by Iodine-125

PubMed Central

Rossi, Barbara; Chen, Yanjin; Li, Hongjun; Zhang, Jing; Sun, Hongpu; Yang, Yihao; Xu, Da; Liu, Xuefeng

2013-01-01

Radiation myelitis is the most serious complication in clinical radiotherapy for spinal metastases. We previously showed that 125I brachytherapy induced apoptosis of spinal cord neurons accompanied by autophagy. In this study, we further investigated the mechanism by which 125I radiation triggered autophagy in neural cells. We found that autophagy induced by 125I radiation was involved in endoplasmic reticulum (ER) stress and mainly dependent on PERK-eIF2α pathway. The expressions of LC3II, ATG12 and PI3K were significantly suppressed in PERK knockout neural cells. Meanwhile, the expressions of phosphorylated-Akt s473 and caspase3/8 all significantly increased in neural cells transfected with a PERK siRNA and which enhanced apoptosis of neurons after 125I radiation. The results were consistent with that by MTT and Annexin-FITC/PT staining. In annimal model of banna pigs with radiation myelitis caused by 125I brachytherapy, we have successfully decreased PERK expression by intrathecal administration of the lentivirus vector. The apoptosis rate was significantly higher than that in control group and which deteriorated radiation myelitis of banna pigs. Thus, autophagy caused by 125I radiation was mainly as an attempt of cell survival at an early stage, but it would be a self-destructive process and promoted the process of apoptosis and necrosis radiated by 125I for more than 72 hours. The study would be useful and helpful to maximize efficiency of radiation therapy in clinical therapy. PMID:24223705

Reduced dose to urethra and rectum with the use of variable needle spacing in prostate brachytherapy: a potential role for robotic technology

PubMed Central

Vyas, Shilpa; Le, Yi; Zhang, Zhe; Armour, Woody

2015-01-01

Purpose Several robotic delivery systems for prostate brachytherapy are under development or in pre-clinical testing. One of the features of robotic brachytherapy is the ability to vary spacing of needles at non-fixed intervals. This feature may play an important role in prostate brachytherapy, which is traditionally template-based with fixed needle spacing of 0.5 cm. We sought to quantify potential reductions in the dose to urethra and rectum by utilizing variable needle spacing, as compared to fixed needle spacing. Material and methods Transrectal ultrasound images from 10 patients were used by 3 experienced planners to create 120 treatment plans. Each planner created 4 plan variations per patient with respect to needle positions: 125I fixed spacing, 125I variable spacing, 103Pd fixed spacing, and 103Pd variable spacing. The primary planning objective was to achieve a prostate V100 of 100% while minimizing dose to urethra and rectum. Results All plans met the objective of achieving prostate V100 of 100%. Combined results for all plans show statistically significant improvements in all assessed dosimetric variables for urethra (Umax, Umean, D30, D5) and rectum (Rmax, Rmean, RV100) when using variable spacing. The dose reductions for mean and maximum urethra dose using variable spacing had p values of 0.011 and 0.024 with 103Pd, and 0.007 and 0.029 with 125I plans. Similarly dose reductions for mean and maximum rectal dose using variable spacing had p values of 0.007 and 0.052 with 103Pd, and 0.012 and 0.037 with 125I plans. Conclusions The variable needle spacing achievable by the use of robotics in prostate brachytherapy allows for reductions in both urethral and rectal planned doses while maintaining prostate dose coverage. Such dosimetric advantages have the potential in translating to significant clinical benefits with the use of robotic brachytherapy. PMID:26622227

Demonstration of a forward iterative method to reconstruct brachytherapy seed configurations from x-ray projections

NASA Astrophysics Data System (ADS)

Murphy, Martin J.; Todor, Dorin A.

2005-06-01

By monitoring brachytherapy seed placement and determining the actual configuration of the seeds in vivo, one can optimize the treatment plan during the process of implantation. Two or more radiographic images from different viewpoints can in principle allow one to reconstruct the configuration of implanted seeds uniquely. However, the reconstruction problem is complicated by several factors: (1) the seeds can overlap and cluster in the images; (2) the images can have distortion that varies with viewpoint when a C-arm fluoroscope is used; (3) there can be uncertainty in the imaging viewpoints; (4) the angular separation of the imaging viewpoints can be small owing to physical space constraints; (5) there can be inconsistency in the number of seeds detected in the images; and (6) the patient can move while being imaged. We propose and conceptually demonstrate a novel reconstruction method that handles all of these complications and uncertainties in a unified process. The method represents the three-dimensional seed and camera configurations as parametrized models that are adjusted iteratively to conform to the observed radiographic images. The morphed model seed configuration that best reproduces the appearance of the seeds in the radiographs is the best estimate of the actual seed configuration. All of the information needed to establish both the seed configuration and the camera model is derived from the seed images without resort to external calibration fixtures. Furthermore, by comparing overall image content rather than individual seed coordinates, the process avoids the need to establish correspondence between seed identities in the several images. The method has been shown to work robustly in simulation tests that simultaneously allow for unknown individual seed positions, uncertainties in the imaging viewpoints and variable image distortion.

Sci-Thur PM – Brachytherapy 02: Positional accuracy in Pd-103 permanent breast seed implant (PBSI) brachytherapy at the Tom Baker Cancer Centre (TBCC)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Frederick, Amy; Watt, Elizabeth; Peacock, Michael

Purpose: This retrospective study aims to quantify the positional accuracy of seed delivery in permanent breast seed implant (PBSI) brachytherapy at the Tom Baker Cancer Centre (TBCC). Methods: Treatment planning and post-implant CT scans for 5 patients were rigidly registered using the MIM Symphony™ software (MIM Software, Cleveland, OH) and used to evaluate differences between planned and implanted seed positions. Total and directional seed displacements were calculated for each patient in a clinically relevant ‘needle coordinate system’, defined relative to the angle of fiducial needle insertion. Results: The overall average total seed displacement was 10±8 mm. Systematic seed displacements weremore » observed in individual patients and the magnitude and direction of these offsets varied among patients. One patient showed a significant directional seed displacement in the shallow-deep direction compared with the other four patients. With the exception of this one patient outlier, no significant systematic directional displacements in the needle coordinate system were observed for this cohort; the average directional displacements were −1±5 mm, 2±3 mm, and −2±4 mm in the shallow-deep, up-down, and right-left directions respectively. Conclusion: With the exception of one patient outlier, the magnitude of seed displacements were relatively consistent among patients. The results indicate that the shallow-deep direction possesses the largest uncertainty for the seed delivery method used at the TBCC. The relatively large uncertainty in seed placement in this direction is expected, as this is the direction of needle insertion. Further work will involve evaluating deflections of delivered needle tracks from their planned positions.« less

SU-F-T-48: Clinical Implementation of Brachytherapy Planning System for COMS Eye Plaques

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ferreira, C; Islam, M; Ahmad, S

Purpose: To commission the Brachytherapy Planning (BP) system (Varian, Palo Alto, CA) for the Collaborative Ocular Melanoma Study (COMS) eye plaques by evaluating dose differences against original plans from Nucletron Planning System (NPS). Methods: NPS system is the primary planning software for COMS-plaques at our facility; however, Brachytherapy Planning 11.0.47 (Varian Medical Systems) is used for secondary check and for seed placement configurations not originally commissioned. Dose comparisons of BP and NPS plans were performed for prescription of 8500 cGy at 5 mm depth and doses to normal structures: opposite retina, inner sclera, macula, optic disk and lens. Plans weremore » calculated for Iodine-125 seeds (OncoSeeds, Model 6711) using COMS-plaques of 10, 12, 14, 16, 18 and 20 mm diameters. An in-house program based on inverse-square was utilized to calculate point doses for comparison as well. Results: The highest dose difference between BP and NPS was 3.7% for the prescription point for all plaques. Doses for BP were higher than doses reported by NPS for all points. The largest percent differences for apex, opposite retina, inner sclera, macula, optic disk, and lens were 3.2%, 0.9%, 13.5%, 20.5%, 15.7% and 2.2%, respectively. The dose calculated by the in-house program was 1.3% higher at the prescription point, and were as high as 42.1%, for points away from the plaque (i.e. opposite retina) when compared to NPS. Conclusion: Doses to the tumor, lens, retina, and optic nerve are paramount for a successful treatment and vision preservation. Both systems are based on TG-43 calculations and assume water medium tissue homogeneity (ρe=1, water medium). Variations seen may result from the different task group versions and/or mathematical algorithms of the software. BP was commissioned to serve as a backup system and it also enables dose calculation in cases where seeds don’t follow conventional placement configuration.« less

MR and CT image fusion for postimplant analysis in permanent prostate seed implants.

PubMed

Polo, Alfredo; Cattani, Federica; Vavassori, Andrea; Origgi, Daniela; Villa, Gaetano; Marsiglia, Hugo; Bellomi, Massimo; Tosi, Giampiero; De Cobelli, Ottavio; Orecchia, Roberto

2004-12-01

To compare the outcome of two different image-based postimplant dosimetry methods in permanent seed implantation. Between October 1999 and October 2002, 150 patients with low-risk prostate carcinoma were treated with (125)I and (103)Pd in our institution. A CT-MRI image fusion protocol was used in 21 consecutive patients treated with exclusive brachytherapy. The accuracy and reproducibility of the method was calculated, and then the CT-based dosimetry was compared with the CT-MRI-based dosimetry using the dose-volume histogram (DVH) related parameters recommended by the American Brachytherapy Society and the American Association of Physicists in Medicine. Our method for CT-MRI image fusion was accurate and reproducible (median shift <1 mm). Differences in prostate volume were found, depending on the image modality used. Quality assurance DVH-related parameters strongly depended on the image modality (CT vs. CT-MRI): V(100) = 82% vs. 88%, p < 0.05. D(90) = 96% vs. 115%, p < 0.05. Those results depend on the institutional implant technique and reflect the importance of lowering inter- and intraobserver discrepancies when outlining prostate and organs at risk for postimplant dosimetry. Computed tomography-MRI fused images allow accurate determination of prostate size, significantly improving the dosimetric evaluation based on DVH analysis. This provides a consistent method to judge a prostate seed implant's quality.

Dosimetry Modeling for Focal Low-Dose-Rate Prostate Brachytherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Al-Qaisieh, Bashar; Mason, Josh, E-mail: joshua.mason@nhs.net; Bownes, Peter

2015-07-15

Purpose: Focal brachytherapy targeted to an individual lesion(s) within the prostate may reduce side effects experienced with whole-gland brachytherapy. The outcomes of a consensus meeting on focal prostate brachytherapy were used to investigate optimal dosimetry of focal low-dose-rate (LDR) prostate brachytherapy targeted using multiparametric magnetic resonance imaging (mp-MRI) and transperineal template prostate mapping (TPM) biopsy, including the effects of random and systematic seed displacements and interseed attenuation (ISA). Methods and Materials: Nine patients were selected according to clinical characteristics and concordance of TPM and mp-MRI. Retrospectively, 3 treatment plans were analyzed for each case: whole-gland (WG), hemi-gland (hemi), and ultra-focalmore » (UF) plans, with 145-Gy prescription dose and identical dose constraints for each plan. Plan robustness to seed displacement and ISA were assessed using Monte Carlo simulations. Results: WG plans used a mean 28 needles and 81 seeds, hemi plans used 17 needles and 56 seeds, and UF plans used 12 needles and 25 seeds. Mean D90 (minimum dose received by 90% of the target) and V100 (percentage of the target that receives 100% dose) values were 181.3 Gy and 99.8% for the prostate in WG plans, 195.7 Gy and 97.8% for the hemi-prostate in hemi plans, and 218.3 Gy and 99.8% for the focal target in UF plans. Mean urethra D10 was 205.9 Gy, 191.4 Gy, and 92.4 Gy in WG, hemi, and UF plans, respectively. Mean rectum D2 cm{sup 3} was 107.5 Gy, 77.0 Gy, and 42.7 Gy in WG, hemi, and UF plans, respectively. Focal plans were more sensitive to seed displacement errors: random shifts with a standard deviation of 4 mm reduced mean target D90 by 14.0%, 20.5%, and 32.0% for WG, hemi, and UF plans, respectively. ISA has a similar impact on dose-volume histogram parameters for all plan types. Conclusions: Treatment planning for focal LDR brachytherapy is feasible. Dose constraints are easily met with a

Clinical Significance of Accounting for Tissue Heterogeneity in Permanent Breast Seed Implant Brachytherapy Planning

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mashouf, Shahram; Department of Radiation Oncology, Sunnybrook Odette Cancer Centre, Toronto, Ontario; Fleury, Emmanuelle

Purpose: The inhomogeneity correction factor (ICF) method provides heterogeneity correction for the fast calculation TG43 formalism in seed brachytherapy. This study compared ICF-corrected plans to their standard TG43 counterparts, looking at their capacity to assess inadequate coverage and/or risk of any skin toxicities for patients who received permanent breast seed implant (PBSI). Methods and Materials: Two-month postimplant computed tomography scans and plans of 140 PBSI patients were used to calculate dose distributions by using the TG43 and the ICF methods. Multiple dose-volume histogram (DVH) parameters of clinical target volume (CTV) and skin were extracted and compared for both ICF and TG43more » dose distributions. Short-term (desquamation and erythema) and long-term (telangiectasia) skin toxicity data were available on 125 and 110 of the patients, respectively, at the time of the study. The predictive value of each DVH parameter of skin was evaluated using the area under the receiver operating characteristic (ROC) curve for each toxicity endpoint. Results: Dose-volume histogram parameters of CTV, calculated using the ICF method, showed an overall decrease compared to TG43, whereas those of skin showed an increase, confirming previously reported findings of the impact of heterogeneity with low-energy sources. The ICF methodology enabled us to distinguish patients for whom the CTV V{sub 100} and V{sub 90} are up to 19% lower compared to TG43, which could present a risk of recurrence not detected when heterogeneity are not accounted for. The ICF method also led to an increase in the prediction of desquamation, erythema, and telangiectasia for 91% of skin DVH parameters studied. Conclusions: The ICF methodology has the advantage of distinguishing any inadequate dose coverage of CTV due to breast heterogeneity, which can be missed by TG43. Use of ICF correction also led to an increase in prediction accuracy of skin toxicities in most cases.« less

Clinical Significance of Accounting for Tissue Heterogeneity in Permanent Breast Seed Implant Brachytherapy Planning.

PubMed

Mashouf, Shahram; Fleury, Emmanuelle; Lai, Priscilla; Merino, Tomas; Lechtman, Eli; Kiss, Alex; McCann, Claire; Pignol, Jean-Philippe

2016-03-15

The inhomogeneity correction factor (ICF) method provides heterogeneity correction for the fast calculation TG43 formalism in seed brachytherapy. This study compared ICF-corrected plans to their standard TG43 counterparts, looking at their capacity to assess inadequate coverage and/or risk of any skin toxicities for patients who received permanent breast seed implant (PBSI). Two-month postimplant computed tomography scans and plans of 140 PBSI patients were used to calculate dose distributions by using the TG43 and the ICF methods. Multiple dose-volume histogram (DVH) parameters of clinical target volume (CTV) and skin were extracted and compared for both ICF and TG43 dose distributions. Short-term (desquamation and erythema) and long-term (telangiectasia) skin toxicity data were available on 125 and 110 of the patients, respectively, at the time of the study. The predictive value of each DVH parameter of skin was evaluated using the area under the receiver operating characteristic (ROC) curve for each toxicity endpoint. Dose-volume histogram parameters of CTV, calculated using the ICF method, showed an overall decrease compared to TG43, whereas those of skin showed an increase, confirming previously reported findings of the impact of heterogeneity with low-energy sources. The ICF methodology enabled us to distinguish patients for whom the CTV V100 and V90 are up to 19% lower compared to TG43, which could present a risk of recurrence not detected when heterogeneity are not accounted for. The ICF method also led to an increase in the prediction of desquamation, erythema, and telangiectasia for 91% of skin DVH parameters studied. The ICF methodology has the advantage of distinguishing any inadequate dose coverage of CTV due to breast heterogeneity, which can be missed by TG43. Use of ICF correction also led to an increase in prediction accuracy of skin toxicities in most cases. Copyright © 2016 Elsevier Inc. All rights reserved.

Air density dependence of the response of the PTW SourceCheck 4pi ionization chamber for 125I brachytherapy seeds.

PubMed

Torres Del Río, J; Tornero-López, A M; Guirado, D; Pérez-Calatayud, J; Lallena, A M

2017-06-01

To analyze the air density dependence of the response of the new SourceCheck 4pi ionization chamber, manufactured by PTW. The air density dependence of three different SourceCheck 4pi chambers was studied by measuring 125 I sources. Measurements were taken by varying the pressure from 746.6 to 986.6hPa in a pressure chamber. Three different HDR 1000 Plus ionization chambers were also analyzed under similar conditions. A linear and a potential-like function of the air density were fitted to experimental data and their achievement in describing them was analyzed. SourceCheck 4pi chamber response showed a residual dependence on the air density once the standard pressure and temperature factor was applied. The chamber response was overestimated when the air density was below that under normal atmospheric conditions. A similar dependence was found for the HDR 1000 Plus chambers analyzed. A linear function of the air density permitted a very good description of this residual dependence, better than with a potential function. No significant variability between the different specimens of the same chamber model studied was found. The effect of overestimation observed in the chamber responses once they are corrected for the standard pressure and temperature may represent a non-negligible ∼4% overestimation in high altitude cities as ours (700m AMSL). This overestimation behaves linearly with the air density in all cases analyzed. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

A novel curvilinear approach for prostate seed implantation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Podder, Tarun K.; Dicker, Adam P.; Hutapea, Parsaoran

Purpose: A new technique called ''curvilinear approach'' for prostate seed implantation has been proposed. The purpose of this study is to evaluate the dosimetric benefit of curvilinear distribution of seeds for low-dose-rate (LDR) prostate brachytherapy. Methods: Twenty LDR prostate brachytherapy cases planned intraoperatively with VariSeed planning system and I-125 seeds were randomly selected as reference rectilinear cases. All the cases were replanned by using curved-needle approach keeping the same individual source strength and the volume receiving 100% of prescribed dose 145 Gy (V{sub 100}). Parameters such as number of needles, seeds, and the dose coverage of the prostate (D{sub 90},more » V{sub 150}, V{sub 200}), urethra (D{sub 30}, D{sub 10}) and rectum (D{sub 5}, V{sub 100}) were compared for the rectilinear and the curvilinear methods. Statistical significance was assessed using two-tailed student's t-test. Results: Reduction of the required number of needles and seeds in curvilinear method were 30.5% (p < 0.001) and 11.8% (p < 0.49), respectively. Dose to the urethra was reduced significantly; D{sub 30} reduced by 10.1% (p < 0.01) and D{sub 10} reduced by 9.9% (p < 0.02). Reduction in rectum dose D{sub 5} was 18.5% (p < 0.03) and V{sub 100} was also reduced from 0.93 cc in rectilinear to 0.21 cc in curvilinear (p < 0.001). Also the V{sub 150} and V{sub 200} coverage of prostate reduced by 18.8% (p < 0.01) and 33.9% (p < 0.001), respectively. Conclusions: Significant improvement in the relevant dosimetric parameters was observed in curvilinear needle approach. Prostate dose homogeneity (V{sub 150}, V{sub 200}) improved while urethral dose was reduced, which might potentially result in better treatment outcome. Reduction in rectal dose could potentially reduce rectal toxicity and complications. Reduction in number of needles would minimize edema and thereby could improve postimplant urinary incontinence. This study indicates that the curvilinear

Calibration of Photon Sources for Brachytherapy

NASA Astrophysics Data System (ADS)

Rijnders, Alex

Source calibration has to be considered an essential part of the quality assurance program in a brachytherapy department. Not only it will ensure that the source strength value used for dose calculation agrees within some predetermined limits to the value stated on the source certificate, but also it will ensure traceability to international standards. At present calibration is most often still given in terms of reference air kerma rate, although calibration in terms of absorbed dose to water would be closer to the users interest. It can be expected that in a near future several standard laboratories will be able to offer this latter service, and dosimetry protocols will have to be adapted in this way. In-air measurement using ionization chambers (e.g. a Baldwin—Farmer ionization chamber for 192Ir high dose rate HDR or pulsed dose rate PDR sources) is still considered the method of choice for high energy source calibration, but because of their ease of use and reliability well type chambers are becoming more popular and are nowadays often recommended as the standard equipment. For low energy sources well type chambers are in practice the only equipment available for calibration. Care should be taken that the chamber is calibrated at the standard laboratory for the same source type and model as used in the clinic, and using the same measurement conditions and setup. Several standard laboratories have difficulties to provide these calibration facilities, especially for the low energy seed sources (125I and 103Pd). Should a user not be able to obtain properly calibrated equipment to verify the brachytherapy sources used in his department, then at least for sources that are replaced on a regular basis, a consistency check program should be set up to ensure a minimal level of quality control before these sources are used for patient treatment.

Chemoembolization and stenting combined with iodine-125 seed strands for the treatment of hepatocellular carcinoma with inferior vena cava obstruction

PubMed Central

LI, WENHUI; DAI, ZHENYU; YAO, LIZHENG; LUO, JIANJUN; YAN, ZHIPING

2015-01-01

The aim of the present study was to investigate the efficacy and safety of stenting combined with radioactive iodine-125 seed strands following chemoembolization for the treatment of patients with hepatocellular carcinoma and inferior vena cava (IVC) obstruction. A retrospective analysis was conducted of 52 hepatocellular carcinoma patients with IVC obstruction. All patients received chemoembolization of tumor-supplying arteries and IVC stents, and 18 patients additionally received iodine-125 seed strands, which were fixed to the stents. Improvement of IVC obstruction and the tumor response rates were compared between the two groups with a median follow-up time of 2.5 months. In both groups the stents were successfully deployed. At the 2-month post-procedural follow-up, the mean diameter of the IVC obstruction site, the mean pressure difference between the distal IVC obstructive segment and the right atrium as well as the obstruction scoring did not differ significantly between the two groups. By contrast, the tumor response rate of the iodine-125 seed strand group was 94.4%, whereas for the group without iodine-125 seed strands it was 35.3% (P<0.001). The combination of stent and iodine-125 seed strands was effective and safe for the treatment of hepatocellular carcinoma with IVC obstruction. PMID:26622424

LDR vs. HDR brachytherapy for localized prostate cancer: the view from radiobiological models.

PubMed

King, Christopher R

2002-01-01

Permanent LDR brachytherapy and temporary HDR brachytherapy are competitive techniques for clinically localized prostate radiotherapy. Although a randomized trial will likely never be conducted comparing these two forms of brachytherapy, a comparative radiobiological modeling analysis proves useful in understanding some of their intrinsic differences, several of which could be exploited to improve outcomes. Radiobiological models based upon the linear quadratic equations are presented for fractionated external beam, fractionated (192)Ir HDR brachytherapy, and (125)I and (103)Pd LDR brachytherapy. These models incorporate the dose heterogeneities present in brachytherapy based upon patient-derived dose volume histograms (DVH) as well as tumor doubling times and repair kinetics. Radiobiological parameters are normalized to correspond to three accepted clinical risk factors based upon T-stage, PSA, and Gleason score to compare models with clinical series. Tumor control probabilities (TCP) for LDR and HDR brachytherapy (as monotherapy or combined with external beam) are compared with clinical bNED survival rates. Predictions are made for dose escalation with HDR brachytherapy regimens. Model predictions for dose escalation with external beam agree with clinical data and validate the models and their underlying assumptions. Both LDR and HDR brachytherapy achieve superior tumor control when compared with external beam at conventional doses (<70 Gy), but similar to results from dose escalation series. LDR brachytherapy as boost achieves superior tumor control than when used as monotherapy. Stage for stage, both LDR and current HDR regimens achieve similar tumor control rates, in agreement with current clinical data. HDR monotherapy with large-dose fraction sizes might achieve superior tumor control compared with LDR, especially if prostate cancer possesses a high sensitivity to dose fractionation (i.e., if the alpha/beta ratio is low). Radiobiological models support the

Brachytherapy Using Elastin-Like Polypeptides with (131)I Inhibit Tumor Growth in Rabbits with VX2 Liver Tumor.

PubMed

Liu, Xinpei; Shen, Yiming; Zhang, Xuqian; Lin, Rui; Jia, Qiang; Chang, Yixiang; Liu, Wenge; Liu, Wentian

2016-10-01

Brachytherapy is a targeted type of radiotherapy utilized in the treatment of cancers. Elastin-like polypeptides are a unique class of genetically engineered peptide polymers that have several attractive properties for brachytherapy. To explore the feasibility and application of brachytherapy for VX2 liver tumor using elastin-like polypeptides with (131)I so as to provide reliable experimental evidence for a new promising treatment of liver cancer. Elastin-like polypeptide as carrier was labeled with (131)I using the iodogen method. Ten eligible rabbits with VX2 liver tumor were randomly divided into the treatment group (n = 5) and control group (n = 5). The treatment group received brachytherapy using elastin-like polypeptide with (131)I, and in the control group, elastin-like polypeptide was injected into the VX2 liver tumor as a control. Periodic biochemical and imaging surveillances were required to assess treatment efficacy. The stability of elastin-like polypeptide with (131)I in vitro was maintained at over 96.8 % for 96 h. Biochemistry and imaging indicated brachytherapy using elastin-like polypeptide with (131)I for liver tumor can improve liver function and inhibit tumor growth (P < 0.05). Elastin-like polypeptide can be an ideal carrier of (131)I and have high labeling efficiency, radiochemical purity and stability. Brachytherapy using elastin-like polypeptide with (131)I for liver tumor is a useful therapy that possesses high antitumor efficacy advantages.

ALGEBRA: ALgorithm for the heterogeneous dosimetry based on GEANT4 for BRAchytherapy.

PubMed

Afsharpour, H; Landry, G; D'Amours, M; Enger, S; Reniers, B; Poon, E; Carrier, J-F; Verhaegen, F; Beaulieu, L

2012-06-07

Task group 43 (TG43)-based dosimetry algorithms are efficient for brachytherapy dose calculation in water. However, human tissues have chemical compositions and densities different than water. Moreover, the mutual shielding effect of seeds on each other (interseed attenuation) is neglected in the TG43-based dosimetry platforms. The scientific community has expressed the need for an accurate dosimetry platform in brachytherapy. The purpose of this paper is to present ALGEBRA, a Monte Carlo platform for dosimetry in brachytherapy which is sufficiently fast and accurate for clinical and research purposes. ALGEBRA is based on the GEANT4 Monte Carlo code and is capable of handling the DICOM RT standard to recreate a virtual model of the treated site. Here, the performance of ALGEBRA is presented for the special case of LDR brachytherapy in permanent prostate and breast seed implants. However, the algorithm is also capable of handling other treatments such as HDR brachytherapy.

Nanodosimetry of (125)I Auger electrons.

PubMed

Bantsar, Aliaksandr; Pszona, Stanislaw

2012-12-01

The nanodosimetric description of the radiation action of Auger electrons on nitrogen targets of nanometric size is presented. Experimental microdosimetry at nanometer scale for Auger electrons has been accomplished with the set-up called Jet Counter. This consists of a pulse-operated valve which injects an expanding nitrogen jet into an interaction chamber where a gaseous sensitive volume of cylindrical shape is created. The ionization cluster size distributions (ICSD) created by Auger electrons emitted by (125)I while crossing a nanometer-sized volume have been measured. The ICSD for the sensitive volumes corresponding to 3 and 12 nm in diameter (in unit density 1 g/cm(3)) irradiated by electrons emitted by a (125)I source were collected and compared with the corresponding Monte Carlo (MC) simulation. The preliminary results of the experiments with Auger electrons of (125)I interacting with a nitrogen jet having nanometric size comparable to a deoxyribonucleic acid (DNA) and nucleosome, showing the discrete spectrum of ICSD with extended cluster size, are described. The presented paper describes for the first time the nanodosimetric experiments with Auger electrons emitted by (125)I. A set of the new descriptors of the radiation quality describing the radiation effect at nanometer level is proposed. The ICSD were determined for the first time for an Auger emitter of (125)I.

Fast dose kernel interpolation using Fourier transform with application to permanent prostate brachytherapy dosimetry.

PubMed

Liu, Derek; Sloboda, Ron S

2014-05-01

Boyer and Mok proposed a fast calculation method employing the Fourier transform (FT), for which calculation time is independent of the number of seeds but seed placement is restricted to calculation grid points. Here an interpolation method is described enabling unrestricted seed placement while preserving the computational efficiency of the original method. The Iodine-125 seed dose kernel was sampled and selected values were modified to optimize interpolation accuracy for clinically relevant doses. For each seed, the kernel was shifted to the nearest grid point via convolution with a unit impulse, implemented in the Fourier domain. The remaining fractional shift was performed using a piecewise third-order Lagrange filter. Implementation of the interpolation method greatly improved FT-based dose calculation accuracy. The dose distribution was accurate to within 2% beyond 3 mm from each seed. Isodose contours were indistinguishable from explicit TG-43 calculation. Dose-volume metric errors were negligible. Computation time for the FT interpolation method was essentially the same as Boyer's method. A FT interpolation method for permanent prostate brachytherapy TG-43 dose calculation was developed which expands upon Boyer's original method and enables unrestricted seed placement. The proposed method substantially improves the clinically relevant dose accuracy with negligible additional computation cost, preserving the efficiency of the original method.

SU-F-J-157: Effect of Contouring Uncertainty in Post Implant Dosimetry of Low-Dose-Rate Prostate Permanent Seed Brachytherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mashouf, S; Merino, T; Ravi, A

Purpose: There is strong evidence relating post-implant dosimetry for low-dose-rate (LDR) prostate seed brachytherapy to local control rates. The delineation of the prostate on CT images, however, represents a challenge due to the lack of soft tissue contrast in order to identify the prostate borders. This study aims at quantifying the sensitivity of clinically relevant dosimetric parameters to uncertainty in the contouring of prostate. Methods: CT images, post-op plans and contours of a cohort of patients (n=43) (low risk=55.8%, intermediate risk=39.5%, high risk=4.7%), who had received prostate seed brachytherapy, were imported into MIM Symphony treatment planning system. The prostate contoursmore » in post-implant CT images were expanded/contracted uniformly for margins of ±1.00 mm, ±2.00 mm, ±3.00 mm, ±4.00 mm and ±5.00 mm. The values for V100 and D90 were extracted from Dose Volume Histograms for each contour and compared. Results: Significant changes were observed in the values of D90 and V100 as well as the number of suboptimal plans for expansion or contraction margins of only few millimeters. Evaluation of coverage based on D90 was found to be less sensitive to expansion errors compared to V100. D90 led to a lower number of implants incorrectly identified with insufficient coverage for expanded contours which increases the accuracy of post-implant QA using CT images compared to V100. Conclusion: In order to establish a successful post implant QA for LDR prostate seed brachytherapy, it is necessary to identify the low and high thresholds of important dose metrics of the target volume such as D90 and V100. Since these parameters are sensitive to target volume definition, accurate identification of prostate borders would help to improve accuracy and predictive value of the post-implant QA process. In this respect, use of imaging modalities such as MRI where prostate is well delineated should prove useful.« less

I-125 ROPES eye plaque dosimetry: Validation of a commercial 3D ophthalmic brachytherapy treatment planning system and independent dose calculation software with GafChromic{sup ®} EBT3 films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poder, Joel; Corde, Stéphanie

Purpose: The purpose of this study was to measure the dose distributions for different Radiation Oncology Physics and Engineering Services, Australia (ROPES) type eye plaques loaded with I-125 (model 6711) seeds using GafChromic{sup ®} EBT3 films, in order to verify the dose distributions in the Plaque Simulator™ (PS) ophthalmic 3D treatment planning system. The brachytherapy module of RADCALC{sup ®} was used to independently check the dose distributions calculated by PS. Correction factors were derived from the measured data to be used in PS to account for the effect of the stainless steel ROPES plaque backing on the 3D dose distribution.Methods:more » Using GafChromic{sup ®} EBT3 films inserted in a specially designed Solid Water™ eye ball phantom, dose distributions were measured three-dimensionally both along and perpendicular to I-125 (model 6711) loaded ROPES eye plaque's central axis (CAX) with 2 mm depth increments. Each measurement was performed in full scatter conditions both with and without the stainless steel plaque backing attached to the eye plaque, to assess its effect on the dose distributions. Results were compared to the dose distributions calculated by Plaque Simulator™ and checked independently with RADCALC{sup ®}.Results: The EBT3 film measurements without the stainless steel backing were found to agree with PS and RADCALC{sup ®} to within 2% and 4%, respectively, on the plaque CAX. Also, RADCALC{sup ®} was found to agree with PS to within 2%. The CAX depth doses measured using EBT3 film with the stainless steel backing were observed to result in a 4% decrease relative to when the backing was not present. Within experimental uncertainty, the 4% decrease was found to be constant with depth and independent of plaque size. Using a constant dose correction factor of T= 0.96 in PS, where the calculated dose for the full water scattering medium is reduced by 4% in every voxel in the dose grid, the effect of the plaque backing was

Metallic artifact mitigation and organ-constrained tissue assignment for Monte Carlo calculations of permanent implant lung brachytherapy.

PubMed

Sutherland, J G H; Miksys, N; Furutani, K M; Thomson, R M

2014-01-01

To investigate methods of generating accurate patient-specific computational phantoms for the Monte Carlo calculation of lung brachytherapy patient dose distributions. Four metallic artifact mitigation methods are applied to six lung brachytherapy patient computed tomography (CT) images: simple threshold replacement (STR) identifies high CT values in the vicinity of the seeds and replaces them with estimated true values; fan beam virtual sinogram replaces artifact-affected values in a virtual sinogram and performs a filtered back-projection to generate a corrected image; 3D median filter replaces voxel values that differ from the median value in a region of interest surrounding the voxel and then applies a second filter to reduce noise; and a combination of fan beam virtual sinogram and STR. Computational phantoms are generated from artifact-corrected and uncorrected images using several tissue assignment schemes: both lung-contour constrained and unconstrained global schemes are considered. Voxel mass densities are assigned based on voxel CT number or using the nominal tissue mass densities. Dose distributions are calculated using the EGSnrc user-code BrachyDose for (125)I, (103)Pd, and (131)Cs seeds and are compared directly as well as through dose volume histograms and dose metrics for target volumes surrounding surgical sutures. Metallic artifact mitigation techniques vary in ability to reduce artifacts while preserving tissue detail. Notably, images corrected with the fan beam virtual sinogram have reduced artifacts but residual artifacts near sources remain requiring additional use of STR; the 3D median filter removes artifacts but simultaneously removes detail in lung and bone. Doses vary considerably between computational phantoms with the largest differences arising from artifact-affected voxels assigned to bone in the vicinity of the seeds. Consequently, when metallic artifact reduction and constrained tissue assignment within lung contours are employed

Metallic artifact mitigation and organ-constrained tissue assignment for Monte Carlo calculations of permanent implant lung brachytherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sutherland, J. G. H.; Miksys, N.; Thomson, R. M., E-mail: rthomson@physics.carleton.ca

2014-01-15

Purpose: To investigate methods of generating accurate patient-specific computational phantoms for the Monte Carlo calculation of lung brachytherapy patient dose distributions. Methods: Four metallic artifact mitigation methods are applied to six lung brachytherapy patient computed tomography (CT) images: simple threshold replacement (STR) identifies high CT values in the vicinity of the seeds and replaces them with estimated true values; fan beam virtual sinogram replaces artifact-affected values in a virtual sinogram and performs a filtered back-projection to generate a corrected image; 3D median filter replaces voxel values that differ from the median value in a region of interest surrounding the voxelmore » and then applies a second filter to reduce noise; and a combination of fan beam virtual sinogram and STR. Computational phantoms are generated from artifact-corrected and uncorrected images using several tissue assignment schemes: both lung-contour constrained and unconstrained global schemes are considered. Voxel mass densities are assigned based on voxel CT number or using the nominal tissue mass densities. Dose distributions are calculated using the EGSnrc user-code BrachyDose for{sup 125}I, {sup 103}Pd, and {sup 131}Cs seeds and are compared directly as well as through dose volume histograms and dose metrics for target volumes surrounding surgical sutures. Results: Metallic artifact mitigation techniques vary in ability to reduce artifacts while preserving tissue detail. Notably, images corrected with the fan beam virtual sinogram have reduced artifacts but residual artifacts near sources remain requiring additional use of STR; the 3D median filter removes artifacts but simultaneously removes detail in lung and bone. Doses vary considerably between computational phantoms with the largest differences arising from artifact-affected voxels assigned to bone in the vicinity of the seeds. Consequently, when metallic artifact reduction and constrained tissue

Effect of tissue composition on dose distribution in brachytherapy with various photon emitting sources

PubMed Central

Ghorbani, Mahdi; Salahshour, Fateme; Haghparast, Abbas; Knaup, Courtney

2014-01-01

Purpose The aim of this study is to compare the dose in various soft tissues in brachytherapy with photon emitting sources. Material and methods 103Pd, 125I, 169Yb, 192Ir brachytherapy sources were simulated with MCNPX Monte Carlo code, and their dose rate constant and radial dose function were compared with the published data. A spherical phantom with 50 cm radius was simulated and the dose at various radial distances in adipose tissue, breast tissue, 4-component soft tissue, brain (grey/white matter), muscle (skeletal), lung tissue, blood (whole), 9-component soft tissue, and water were calculated. The absolute dose and relative dose difference with respect to 9-component soft tissue was obtained for various materials, sources, and distances. Results There was good agreement between the dosimetric parameters of the sources and the published data. Adipose tissue, breast tissue, 4-component soft tissue, and water showed the greatest difference in dose relative to the dose to the 9-component soft tissue. The other soft tissues showed lower dose differences. The dose difference was also higher for 103Pd source than for 125I, 169Yb, and 192Ir sources. Furthermore, greater distances from the source had higher relative dose differences and the effect can be justified due to the change in photon spectrum (softening or hardening) as photons traverse the phantom material. Conclusions The ignorance of soft tissue characteristics (density, composition, etc.) by treatment planning systems incorporates a significant error in dose delivery to the patient in brachytherapy with photon sources. The error depends on the type of soft tissue, brachytherapy source, as well as the distance from the source. PMID:24790623

The effects of metallic implants on electroporation therapies: feasibility of irreversible electroporation for brachytherapy salvage.

PubMed

Neal, Robert E; Smith, Ryan L; Kavnoudias, Helen; Rosenfeldt, Franklin; Ou, Ruchong; Mclean, Catriona A; Davalos, Rafael V; Thomson, Kenneth R

2013-12-01

Electroporation-based therapies deliver brief electric pulses into a targeted volume to destabilize cellular membranes. Nonthermal irreversible electroporation (IRE) provides focal ablation with effects dependent on the electric field distribution, which changes in heterogeneous environments. It should be determined if highly conductive metallic implants in targeted regions, such as radiotherapy brachytherapy seeds in prostate tissue, will alter treatment outcomes. Theoretical and experimental models determine the impact of prostate brachytherapy seeds on IRE treatments. This study delivered IRE pulses in nonanimal, as well as in ex vivo and in vivo tissue, with and in the absence of expired radiotherapy seeds. Electrical current was measured and lesion dimensions were examined macroscopically and with magnetic resonance imaging. Finite-element treatment simulations predicted the effects of brachytherapy seeds in the targeted region on electrical current, electric field, and temperature distributions. There was no significant difference in electrical behavior in tissue containing a grid of expired radiotherapy seeds relative to those without seeds for nonanimal, ex vivo, and in vivo experiments (all p > 0.1). Numerical simulations predict no significant alteration of electric field or thermal effects (all p > 0.1). Histology showed cellular necrosis in the region near the electrodes and seeds within the ablation region; however, there were no seeds beyond the ablation margins. This study suggests that electroporation therapies can be implemented in regions containing small metallic implants without significant changes to electrical and thermal effects relative to use in tissue without the implants. This supports the ability to use IRE as a salvage therapy option for brachytherapy.

AAPM and GEC-ESTRO guidelines for image-guided robotic brachytherapy: report of Task Group 192.

PubMed

Podder, Tarun K; Beaulieu, Luc; Caldwell, Barrett; Cormack, Robert A; Crass, Jostin B; Dicker, Adam P; Fenster, Aaron; Fichtinger, Gabor; Meltsner, Michael A; Moerland, Marinus A; Nath, Ravinder; Rivard, Mark J; Salcudean, Tim; Song, Danny Y; Thomadsen, Bruce R; Yu, Yan

2014-10-01

In the last decade, there have been significant developments into integration of robots and automation tools with brachytherapy delivery systems. These systems aim to improve the current paradigm by executing higher precision and accuracy in seed placement, improving calculation of optimal seed locations, minimizing surgical trauma, and reducing radiation exposure to medical staff. Most of the applications of this technology have been in the implantation of seeds in patients with early-stage prostate cancer. Nevertheless, the techniques apply to any clinical site where interstitial brachytherapy is appropriate. In consideration of the rapid developments in this area, the American Association of Physicists in Medicine (AAPM) commissioned Task Group 192 to review the state-of-the-art in the field of robotic interstitial brachytherapy. This is a joint Task Group with the Groupe Européen de Curiethérapie-European Society for Radiotherapy & Oncology (GEC-ESTRO). All developed and reported robotic brachytherapy systems were reviewed. Commissioning and quality assurance procedures for the safe and consistent use of these systems are also provided. Manual seed placement techniques with a rigid template have an estimated in vivo accuracy of 3-6 mm. In addition to the placement accuracy, factors such as tissue deformation, needle deviation, and edema may result in a delivered dose distribution that differs from the preimplant or intraoperative plan. However, real-time needle tracking and seed identification for dynamic updating of dosimetry may improve the quality of seed implantation. The AAPM and GEC-ESTRO recommend that robotic systems should demonstrate a spatial accuracy of seed placement ≤1.0 mm in a phantom. This recommendation is based on the current performance of existing robotic brachytherapy systems and propagation of uncertainties. During clinical commissioning, tests should be conducted to ensure that this level of accuracy is achieved. These tests should

AAPM and GEC-ESTRO guidelines for image-guided robotic brachytherapy: Report of Task Group 192

DOE Office of Scientific and Technical Information (OSTI.GOV)

Podder, Tarun K., E-mail: tarun.podder@uhhospitals.org; Beaulieu, Luc; Caldwell, Barrett

In the last decade, there have been significant developments into integration of robots and automation tools with brachytherapy delivery systems. These systems aim to improve the current paradigm by executing higher precision and accuracy in seed placement, improving calculation of optimal seed locations, minimizing surgical trauma, and reducing radiation exposure to medical staff. Most of the applications of this technology have been in the implantation of seeds in patients with early-stage prostate cancer. Nevertheless, the techniques apply to any clinical site where interstitial brachytherapy is appropriate. In consideration of the rapid developments in this area, the American Association of Physicistsmore » in Medicine (AAPM) commissioned Task Group 192 to review the state-of-the-art in the field of robotic interstitial brachytherapy. This is a joint Task Group with the Groupe Européen de Curiethérapie-European Society for Radiotherapy and Oncology (GEC-ESTRO). All developed and reported robotic brachytherapy systems were reviewed. Commissioning and quality assurance procedures for the safe and consistent use of these systems are also provided. Manual seed placement techniques with a rigid template have an estimated in vivo accuracy of 3–6 mm. In addition to the placement accuracy, factors such as tissue deformation, needle deviation, and edema may result in a delivered dose distribution that differs from the preimplant or intraoperative plan. However, real-time needle tracking and seed identification for dynamic updating of dosimetry may improve the quality of seed implantation. The AAPM and GEC-ESTRO recommend that robotic systems should demonstrate a spatial accuracy of seed placement ≤1.0 mm in a phantom. This recommendation is based on the current performance of existing robotic brachytherapy systems and propagation of uncertainties. During clinical commissioning, tests should be conducted to ensure that this level of accuracy is achieved. These

125I eye plaque dose distribution including penumbra characteristics.

PubMed

de la Zerda, A; Chiu-Tsao, S T; Lin, J; Boulay, L L; Kanna, I; Kim, J H; Tsao, H S

1996-03-01

The two main purposes of this work are (1) to determine the penumbra characteristics for 125I eye plaque and the relative influence of the plaque and eye-air interface on the dose distribution, and (2) to initiate development of a treatment planning algorithm for clinical dose calculations. Dose was measured in a newly designed solid water eye phantom for an 125I (6711) seed at the center of a 20 mm COMS eye plaque using thermoluminescent dosimeter (TLD) "cubes" and "minichips" inside and outside the eye, in the longitudinal and transverse central planes. TLD cubes were used in most locations, except for short distances from the seed and in the penumbra region. In the presence of both the plaque and the eye-air interface, the dose along the central axis was found to be reduced by 10% at 1 cm and up to 20% at 2.5 cm, relative to the bulk homogeneous phantom case. In addition, the overall dose reduction was greater for larger off-axis coordinates at a given depth. The penumbra characteristics due to the lip collimation were quantified, particularly the dependence of penumbra center and width on depth. Only small differences were observed between the profiles in the transverse and longitudinal planes. In the bulk geometry (without the eye-air interface), the dose reduction due to the presence of the plaque alone was found to be 7% at a depth of 2.5 cm. The additional reduction of 13% observed, with the presence of eye-air interface (20% combined), can be attributed to the lack of backscattering from the air in front of the eye. The dose-reduction effect due to the anterior air interface alone became unnoticeable at a depth of 1.1 cm (1.5 cm from the eye-air interface). An analytic fit to measured data was developed for clinical dose calculations for a centrally loaded seed. The central axis values of the dose rates multiplied by distance squared, Dr2, were fitted with a double exponential function of depth. The off-axis profile of Dr2, at a given depth, was

Feasibility of vibro-acoustography with a quasi-2D ultrasound array transducer for detection and localizing of permanent prostate brachytherapy seeds: A pilot ex vivo study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mehrmohammadi, Mohammad; Kinnick, Randall R.; Fatemi, Mostafa, E-mail: fatemi.mostafa@mayo.edu

2014-09-15

Purpose: Effective permanent prostate brachytherapy (PPB) requires precise placement of radioactive seeds in and around the prostate. The impetus for this research is to examine a new ultrasound-based imaging modality, vibro-acoustography (VA), which may serve to provide a high rate of PPB seed detection while also effecting enhanced prostate imaging. The authors investigate the ability of VA, implemented on a clinical ultrasound (US) scanner and equipped with a quasi-2D (Q2D) array US transducer, to detect and localize PPB seeds in excised prostate specimens. Methods: Nonradioactive brachytherapy seeds were implanted into four excised cadaver prostates. A clinical US scanner equipped withmore » a Q2D array US transducer was customized to acquire both US and C-scan VA images at various depths. The VA images were then used to detect and localize the implanted seeds in prostate tissue. To validate the VA results, computed tomography (CT) images of the same tissue samples were obtained to serve as the reference by which to evaluate the performance of VA in PPB seed detection. Results: The results indicate that VA is capable of accurately identifying the presence and distribution of PPB seeds with a high imaging contrast. Moreover, a large ratio of the PPB seeds implanted into prostate tissue samples could be detected through acquired VA images. Using CT-based seed identification as the standard, VA was capable of detecting 74%–92% of the implanted seeds. Additionally, the angular independency of VA in detecting PPB seeds was demonstrated through a well-controlled phantom experiment. Conclusions: Q2DVA detected a substantial portion of the seeds by using a 2D array US transducer in excised prostate tissue specimens. While VA has inherent advantages associated with conventional US imaging, it has the additional advantage of permitting detection of PPB seeds independent of their orientation. These results suggest the potential of VA as a method for PPB imaging that

Feasibility of vibro-acoustography with a quasi-2D ultrasound array transducer for detection and localizing of permanent prostate brachytherapy seeds: A pilot ex vivo study

PubMed Central

Mehrmohammadi, Mohammad; Alizad, Azra; Kinnick, Randall R.; Davis, Brian J.; Fatemi, Mostafa

2014-01-01

Purpose: Effective permanent prostate brachytherapy (PPB) requires precise placement of radioactive seeds in and around the prostate. The impetus for this research is to examine a new ultrasound-based imaging modality, vibro-acoustography (VA), which may serve to provide a high rate of PPB seed detection while also effecting enhanced prostate imaging. The authors investigate the ability of VA, implemented on a clinical ultrasound (US) scanner and equipped with a quasi-2D (Q2D) array US transducer, to detect and localize PPB seeds in excised prostate specimens. Methods: Nonradioactive brachytherapy seeds were implanted into four excised cadaver prostates. A clinical US scanner equipped with a Q2D array US transducer was customized to acquire both US and C-scan VA images at various depths. The VA images were then used to detect and localize the implanted seeds in prostate tissue. To validate the VA results, computed tomography (CT) images of the same tissue samples were obtained to serve as the reference by which to evaluate the performance of VA in PPB seed detection. Results: The results indicate that VA is capable of accurately identifying the presence and distribution of PPB seeds with a high imaging contrast. Moreover, a large ratio of the PPB seeds implanted into prostate tissue samples could be detected through acquired VA images. Using CT-based seed identification as the standard, VA was capable of detecting 74%–92% of the implanted seeds. Additionally, the angular independency of VA in detecting PPB seeds was demonstrated through a well-controlled phantom experiment. Conclusions: Q2DVA detected a substantial portion of the seeds by using a 2D array US transducer in excised prostate tissue specimens. While VA has inherent advantages associated with conventional US imaging, it has the additional advantage of permitting detection of PPB seeds independent of their orientation. These results suggest the potential of VA as a method for PPB imaging that

Gamma spectrometry and chemical characterization of ceramic seeds with samarium-153 and holmium-166 for brachytherapy proposal.

PubMed

Valente, Eduardo S; Campos, Tarcísio P R

2010-12-01

Ceramic seeds were synthesized by the sol-gel technique with Si:Sm:Ca and Si:Ho:Ca. One set of seeds was irradiated in the TRIGA type nuclear reactor IPR-R1 and submitted to instrumental neutron activation analysis (INAA), K(0) method, to determine mass percentage concentration of natural samarium and holmium in the seed as well as to determine all existing radionuclides and their activities. Attention was paid to discrimination of Si-31, Ca-40, Ca-45, Ca-47, Ca-49, Sm-145, Sm-155, Sm-153 and Ho-166. A second sample was submitted to atomic emission spectrometry (ICP-AES) also to determine samarium and holmium concentrations in weight. A third sample was submitted to X-ray fluorescence spectrometry to qualitatively determine chemical composition. The measured activity was due to Sm-153 and Ho-166 with a well-characterized gamma spectrum. The X-ray fluorescence spectrum demonstrated that there is no discrepancy in seed composition. The maximum ranges in the water of beta particles from Sm-153 and Ho-166 decay were evaluated, as well as the dose rate and total dose delivered within the volume delimited by the range of the beta particles. The results are relevant for investigation of the viability of producing Sm-153 and Ho-166 radioactive seeds for use in brachytherapy. Copyright 2010 Elsevier Ltd. All rights reserved.

Low dose rate brachytherapy (LDR-BT) as monotherapy for early stage prostate cancer in Italy: practice and outcome analysis in a series of 2237 patients from 11 institutions

PubMed Central

Fellin, Giovanni; Mirri, Maria A; Santoro, Luigi; Divan, Claudio; Mussari, Salvatore; Ziglio, Francesco; La Face, Beniamino; Barbera, Fernando; Buglione, Michela; Bandera, Laura; Ghedi, Barbara; Di Muzio, Nadia G; Losa, Andrea; Mangili, Paola; Nava, Luciano; Chiarlone, Renato; Ciscognetti, Nunzia; Gastaldi, Emilio; Cattani, Federica; Spoto, Ruggero; Vavassori, Andrea; Giglioli, Francesca R; Guarneri, Alessia; Cerboneschi, Valentina; Mignogna, Marcello; Paoluzzi, Mauro; Ravaglia, Valentina; Chiumento, Costanza; Clemente, Stefania; Fusco, Vincenzo; Santini, Roberto; Stefanacci, Marco; Mangiacotti, Francesco P; Martini, Marco; Palloni, Tiziana; Schinaia, Giuseppe; Lazzari, Grazia; Silvano, Giovanni; Magrini, Stefano; Ricardi, Umberto; Santoni, Riccardo; Orecchia, Roberto

2016-01-01

Objective: Low-dose-rate brachytherapy (LDR-BT) in localized prostate cancer is available since 15 years in Italy. We realized the first national multicentre and multidisciplinary data collection to evaluate LDR-BT practice, given as monotherapy, and outcome in terms of biochemical failure. Methods: Between May 1998 and December 2011, 2237 patients with early-stage prostate cancer from 11 Italian community and academic hospitals were treated with iodine-125 (125I) or palladium-103 LDR-BT as monotherapy and followed up for at least 2 years. 125I seeds were implanted in 97.7% of the patients: the mean dose received by 90% of target volume was 145 Gy; the mean target volume receiving 100% of prescribed dose (V100) was 91.1%. Biochemical failure-free survival (BFFS), disease-specific survival (DSS) and overall survival (OS) were estimated using Kaplan–Meier method. Log-rank test and multivariable Cox regression were used to evaluate the relationship of covariates with outcomes. Results: Median follow-up time was 65 months. 5- and 7-year DSS, OS and BFFS were 99 and 98%, 94 and 89%, and 92 and 88%, respectively. At multivariate analysis, the National Comprehensive Cancer Network score (p < 0.0001) and V100 (p = 0.09) were correlated with BFFS, with V100 effect significantly different between patients at low risk and those at intermediate/high risk (p = 0.04). Short follow-up and lack of toxicity data represent the main limitations for a global evaluation of LDR-BT. Conclusion: This first multicentre Italian report confirms LDR-BT as an excellent curative modality for low-/intermediate-risk prostate cancer. Advances in knowledge: Multidisciplinary teams may help to select adequately patients to be treated with brachytherapy, with a direct impact on the implant quality and, possibly, on outcome. PMID:27384381

Low dose rate brachytherapy (LDR-BT) as monotherapy for early stage prostate cancer in Italy: practice and outcome analysis in a series of 2237 patients from 11 institutions.

PubMed

Fellin, Giovanni; Mirri, Maria A; Santoro, Luigi; Jereczek-Fossa, Barbara A; Divan, Claudio; Mussari, Salvatore; Ziglio, Francesco; La Face, Beniamino; Barbera, Fernando; Buglione, Michela; Bandera, Laura; Ghedi, Barbara; Di Muzio, Nadia G; Losa, Andrea; Mangili, Paola; Nava, Luciano; Chiarlone, Renato; Ciscognetti, Nunzia; Gastaldi, Emilio; Cattani, Federica; Spoto, Ruggero; Vavassori, Andrea; Giglioli, Francesca R; Guarneri, Alessia; Cerboneschi, Valentina; Mignogna, Marcello; Paoluzzi, Mauro; Ravaglia, Valentina; Chiumento, Costanza; Clemente, Stefania; Fusco, Vincenzo; Santini, Roberto; Stefanacci, Marco; Mangiacotti, Francesco P; Martini, Marco; Palloni, Tiziana; Schinaia, Giuseppe; Lazzari, Grazia; Silvano, Giovanni; Magrini, Stefano; Ricardi, Umberto; Santoni, Riccardo; Orecchia, Roberto

2016-09-01

Low-dose-rate brachytherapy (LDR-BT) in localized prostate cancer is available since 15 years in Italy. We realized the first national multicentre and multidisciplinary data collection to evaluate LDR-BT practice, given as monotherapy, and outcome in terms of biochemical failure. Between May 1998 and December 2011, 2237 patients with early-stage prostate cancer from 11 Italian community and academic hospitals were treated with iodine-125 ((125)I) or palladium-103 LDR-BT as monotherapy and followed up for at least 2 years. (125)I seeds were implanted in 97.7% of the patients: the mean dose received by 90% of target volume was 145 Gy; the mean target volume receiving 100% of prescribed dose (V100) was 91.1%. Biochemical failure-free survival (BFFS), disease-specific survival (DSS) and overall survival (OS) were estimated using Kaplan-Meier method. Log-rank test and multivariable Cox regression were used to evaluate the relationship of covariates with outcomes. Median follow-up time was 65 months. 5- and 7-year DSS, OS and BFFS were 99 and 98%, 94 and 89%, and 92 and 88%, respectively. At multivariate analysis, the National Comprehensive Cancer Network score (p < 0.0001) and V100 (p = 0.09) were correlated with BFFS, with V100 effect significantly different between patients at low risk and those at intermediate/high risk (p = 0.04). Short follow-up and lack of toxicity data represent the main limitations for a global evaluation of LDR-BT. This first multicentre Italian report confirms LDR-BT as an excellent curative modality for low-/intermediate-risk prostate cancer. Multidisciplinary teams may help to select adequately patients to be treated with brachytherapy, with a direct impact on the implant quality and, possibly, on outcome.

The Effects of Metallic Implants on Electroporation Therapies: Feasibility of Irreversible Electroporation for Brachytherapy Salvage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Neal, Robert E., E-mail: robert.neal@alfred.org.au; Smith, Ryan L., E-mail: ryan.smith@wbrc.org.au; Kavnoudias, Helen, E-mail: H.Kavnoudias@alfred.org.au

2013-12-15

Purpose: Electroporation-based therapies deliver brief electric pulses into a targeted volume to destabilize cellular membranes. Nonthermal irreversible electroporation (IRE) provides focal ablation with effects dependent on the electric field distribution, which changes in heterogeneous environments. It should be determined if highly conductive metallic implants in targeted regions, such as radiotherapy brachytherapy seeds in prostate tissue, will alter treatment outcomes. Theoretical and experimental models determine the impact of prostate brachytherapy seeds on IRE treatments. Materials and Methods: This study delivered IRE pulses in nonanimal, as well as in ex vivo and in vivo tissue, with and in the absence of expiredmore » radiotherapy seeds. Electrical current was measured and lesion dimensions were examined macroscopically and with magnetic resonance imaging. Finite-element treatment simulations predicted the effects of brachytherapy seeds in the targeted region on electrical current, electric field, and temperature distributions. Results: There was no significant difference in electrical behavior in tissue containing a grid of expired radiotherapy seeds relative to those without seeds for nonanimal, ex vivo, and in vivo experiments (all p > 0.1). Numerical simulations predict no significant alteration of electric field or thermal effects (all p > 0.1). Histology showed cellular necrosis in the region near the electrodes and seeds within the ablation region; however, there were no seeds beyond the ablation margins. Conclusion: This study suggests that electroporation therapies can be implemented in regions containing small metallic implants without significant changes to electrical and thermal effects relative to use in tissue without the implants. This supports the ability to use IRE as a salvage therapy option for brachytherapy.« less

Brachytherapy for Prostate Cancer: A Systematic Review

PubMed Central

Koukourakis, Georgios; Kelekis, Nikolaos; Armonis, Vassilios; Kouloulias, Vassilios

2009-01-01

Low-dose rate brachytherapy has become a mainstream treatment option for men diagnosed with prostate cancer because of excellent long-term treatment outcomes in low-, intermediate-, and high-risk patients. To a great extend due to patient lead advocacy for minimally invasive treatment options, high-quality prostate implants have become widely available in the US, Europe, and Japan. High-dose-rate (HDR) afterloading brachytherapy in the management of localised prostate cancer has practical, physical, and biological advantages over low-dose-rate seed brachytherapy. There are no free live sources used, no risk of source loss, and since the implant is a temporary procedure following discharge no issues with regard to radioprotection use of existing facilities exist. Patients with localized prostate cancer may benefit from high-dose-rate brachytherapy, which may be used alone in certain circumstances or in combination with external-beam radiotherapy in other settings. The purpose of this paper is to present the essentials of brachytherapies techniques along with the most important studies that support their effectiveness in the treatment of prostate cancer. PMID:19730753

WE-A-17A-11: Implanted Brachytherapy Seed Movement Due to Transrectal Ultrasound Probe-Induced Prostate Deformation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, D; Usmani, N; Sloboda, R

Purpose: To characterize the movement of implanted brachytherapy seeds due to transrectal ultrasound probe-induced prostate deformation and to estimate the effects on prostate dosimetry. Methods: Implanted probe-in and probe-removed seed distributions were reconstructed for 10 patients using C-arm fluoroscopy imaging. The prostate was delineated on ultrasound and registered to the fluoroscopy seeds using a visible subset of seeds and residual needle tracks. A linear tensor and shearing model correlated the seed movement with position. The seed movement model was used to infer the underlying prostate deformation and to simulate the prostate contour without probe compression. Changes in prostate and surrogatemore » urethra dosimetry were calculated. Results: Seed movement patterns reflecting elastic decompression, lateral shearing, and rectal bending were observed. Elastic decompression was characterized by anterior-posterior expansion and superior-inferior and lateral contractions. For lateral shearing, anterior movement up to 6 mm was observed for extraprostatic seeds in the lateral peripheral region. The average intra-prostatic seed movement was 1.3 mm, and the residual after linear modeling was 0.6 mm. Prostate D90 increased by 4 Gy on average (8 Gy max) and was correlated with elastic decompression. For selected patients, lateral shearing resulted in differential change in D90 of 7 Gy between anterior and posterior quadrants, and increase in whole prostate D90 of 4 Gy. Urethra D10 increased by 4 Gy. Conclusion: Seed movement upon probe removal was characterized. The proposed model captured the linear correlation between seed movement and position. Whole prostate dose coverage increased slightly, due to the small but systematic seed movement associated with elastic decompression. Lateral shearing movement increased dose coverage in the anterior-lateral region, at the expense of the posterior-lateral region. The effect on whole prostate D90 was smaller due to

3D MR-Spectroscopic Imaging Assessment of Metabolic Activity in the Prostate During the PSA 'Bounce' Following {sup 125}Iodine Brachytherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kirilova, Anna; Damyanovich, Andrei; Crook, Juanita, E-mail: jcrook@bccancer.bc.c

2011-02-01

Purpose: A temporary increase in prostate-specific antigen (PSA) values is observed in 30%-40% of men following {sup 125} I brachytherapy (BT) for prostate cancer. We present the results of a study to characterize prostate metabolic activity during the PSA 'bounce' and to correlate metabolic changes with PSA levels using three-dimensional magnetic resonance spectroscopic imaging (3D-MRSI). Methods and Materials: 3D-MRSI was performed in 24 patients during the PSA bounce. Eight of these had also had a baseline 3D-MRSI scan before BT for the purpose of tumor mapping. The 3D-MRSI was repeated at 6- and 12-month intervals, and PSA levels were monitoredmore » every 3 months. Twenty-one of the patients had favorable-risk prostate cancer, and 3 had intermediate risk. Results: The choline+creatine signal intensity, although markedly reduced, was observable following BT. Diffuse activity not corresponding to original biopsy-positive sites was observed in 22 cases, and 2 cases were documented to have local recurrence. No statistically significant correlation between metabolic activity and PSA levels at each interval was found. Conclusion: Post-BT prostate 3D-MRSI shows evidence of diffuse metabolic activity unrelated to residual malignancy. This supports the benign nature of the PSA bounce and suggests an inflammatory etiology. In the situation of a rising PSA, observation of focal activity on MRI/3D-MRSI could be a useful adjunct to suggest local recurrence at an earlier interval after brachytherapy when prostate biopsies would still be unhelpful. Longer follow-up is necessary to confirm the complex relationship between metabolic activity and PSA levels.« less

COMP report: CPQR technical quality control guidelines for low-dose-rate permanent seed brachytherapy.

PubMed

Beaulieu, Luc; Radford, Dee-Ann; Eduardo Villarreal-Barajas, J

2018-03-14

The Canadian Organization of Medical Physicists (COMP), in close partnership with the Canadian Partnership for Quality Radiotherapy (CPQR) has developed a series of Technical Quality Control (TQC) guidelines for radiation treatment equipment. These guidelines outline the performance objectives that equipment should meet in order to ensure an acceptable level of radiation treatment quality. The TQC guidelines have been rigorously reviewed and field tested in a variety of Canadian radiation treatment facilities. The development process enables rapid review and update to keep the guidelines current with changes in technology. This article contains detailed performance objectives and safety criteria for low-dose-rate (LDR) permanent seed brachytherapy. © 2018 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

DTI and pathological changes in a rabbit model of radiation injury to the spinal cord after 125I radioactive seed implantation

PubMed Central

Cao, Xia; Fang, Le; Cui, Chuan-yu; Gao, Shi; Wang, Tian-wei

2018-01-01

Excessive radiation exposure may lead to edema of the spinal cord and deterioration of the nervous system. Magnetic resonance imaging can be used to judge and assess the extent of edema and to evaluate pathological changes and thus may be used for the evaluation of spinal cord injuries caused by radiation therapy. Radioactive 125I seeds to irradiate 90% of the spinal cord tissue at doses of 40–100 Gy (D90) were implanted in rabbits at T10 to induce radiation injury, and we evaluated their safety for use in the spinal cord. Diffusion tensor imaging showed that with increased D90, the apparent diffusion coefficient and fractional anisotropy values were increased. Moreover, pathological damage of neurons and microvessels in the gray matter and white matter was aggravated. At 2 months after implantation, obvious pathological injury was visible in the spinal cords of each group. Magnetic resonance diffusion tensor imaging revealed the radiation injury to the spinal cord, and we quantified the degree of spinal cord injury through apparent diffusion coefficient and fractional anisotropy. PMID:29623940

Poster - Thur Eve - 06: Comparison of an open source genetic algorithm to the commercially used IPSA for generation of seed distributions in LDR prostate brachytherapy.

PubMed

McGeachy, P; Khan, R

2012-07-01

In early stage prostate cancer, low dose rate (LDR) prostate brachytherapy is a favorable treatment modality, where small radioactive seeds are permanently implanted throughout the prostate. Treatment centres currently rely on a commercial optimization algorithm, IPSA, to generate seed distributions for treatment plans. However, commercial software does not allow the user access to the source code, thus reducing the flexibility for treatment planning and impeding any implementation of new and, perhaps, improved clinical techniques. An open source genetic algorithm (GA) has been encoded in MATLAB to generate seed distributions for a simplified prostate and urethra model. To assess the quality of the seed distributions created by the GA, both the GA and IPSA were used to generate seed distributions for two clinically relevant scenarios and the quality of the GA distributions relative to IPSA distributions and clinically accepted standards for seed distributions was investigated. The first clinically relevant scenario involved generating seed distributions for three different prostate volumes (19.2 cc, 32.4 cc, and 54.7 cc). The second scenario involved generating distributions for three separate seed activities (0.397 mCi, 0.455 mCi, and 0.5 mCi). Both GA and IPSA met the clinically accepted criteria for the two scenarios, where distributions produced by the GA were comparable to IPSA in terms of full coverage of the prostate by the prescribed dose, and minimized dose to the urethra, which passed straight through the prostate. Further, the GA offered improved reduction of high dose regions (i.e hot spots) within the planned target volume. © 2012 American Association of Physicists in Medicine.

Real-time computed tomography dosimetry during ultrasound-guided brachytherapy for prostate cancer.

PubMed

Kaplan, Irving D; Meskell, Paul; Oldenburg, Nicklas E; Saltzman, Brian; Kearney, Gary P; Holupka, Edward J

2006-01-01

Ultrasound-guided implantation of permanent radioactive seeds is a treatment option for localized prostate cancer. Several techniques have been described for the optimal placement of the seeds in the prostate during this procedure. Postimplantation dosimetric calculations are performed after the implant. Areas of underdosing can only be corrected with either an external beam boost or by performing a second implant. We demonstrate the feasibility of performing computed tomography (CT)-based postplanning during the ultrasound-guided implant and subsequently correcting for underdosed areas. Ultrasound-guided brachytherapy is performed on a modified CT table with general anesthesia. The postplanning CT scan is performed after the implant, while the patient is still under anesthesia. Additional seeds are implanted into "cold spots," and the resultant dosimetry confirmed with CT. Intraoperative postplanning was successfully performed. Dose-volume histograms demonstrated adequate dose coverage during the initial implant, but on detailed analysis, for some patients, areas of underdosing were observed either at the apex or the peripheral zone. Additional seeds were implanted to bring these areas to prescription dose. Intraoperative postplanning is feasible during ultrasound-guided brachytherapy for prostate cancer. Although the postimplant dose-volume histograms for all patients, before the implantation of additional seeds, were adequate according to the American Brachytherapy Society criteria, specific critical areas can be underdosed. Additional seeds can then be implanted to optimize the dosimetry and reduce the risk of underdosing areas of cancer.

History of dose specification in Brachytherapy: From Threshold Erythema Dose to Computational Dosimetry

NASA Astrophysics Data System (ADS)

Williamson, Jeffrey F.

2006-09-01

This paper briefly reviews the evolution of brachytherapy dosimetry from 1900 to the present. Dosimetric practices in brachytherapy fall into three distinct eras: During the era of biological dosimetry (1900-1938), radium pioneers could only specify Ra-226 and Rn-222 implants in terms of the mass of radium encapsulated within the implanted sources. Due to the high energy of its emitted gamma rays and the long range of its secondary electrons in air, free-air chambers could not be used to quantify the output of Ra-226 sources in terms of exposure. Biological dosimetry, most prominently the threshold erythema dose, gained currency as a means of intercomparing radium treatments with exposure-calibrated orthovoltage x-ray units. The classical dosimetry era (1940-1980) began with successful exposure standardization of Ra-226 sources by Bragg-Gray cavity chambers. Classical dose-computation algorithms, based upon 1-D buildup factor measurements and point-source superposition computational algorithms, were able to accommodate artificial radionuclides such as Co-60, Ir-192, and Cs-137. The quantitative dosimetry era (1980- ) arose in response to the increasing utilization of low energy K-capture radionuclides such as I-125 and Pd-103 for which classical approaches could not be expected to estimate accurate correct doses. This led to intensive development of both experimental (largely TLD-100 dosimetry) and Monte Carlo dosimetry techniques along with more accurate air-kerma strength standards. As a result of extensive benchmarking and intercomparison of these different methods, single-seed low-energy radionuclide dose distributions are now known with a total uncertainty of 3%-5%.

SU-F-T-61: Treatment Planning Observations for the CivaSheet Directional Brachytherapy Device Using VariSeed 9.0

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rivard, MJ; Rothley, DJ

2016-06-15

Purpose: The VariSeed 9.0 brachytherapy TPS is recently available and has new features such as ability to rotate a brachytherapy source away from normal to the imaging plane. Consequently, a dosimetric analysis was performed for a directional brachytherapy source (CivaSheet) with tests of this functionality and experiences from clinical treatment planning were documented. These observations contribute to safe, practical, and accurate use of such new software features. Methods: Several tests were established to evaluate the new rotational feature, specific to the CivaSheet for the first patients treated using this new brachytherapy device. These included suitability of imaging slice-thickness and in-planemore » resolution, window/level adjustments for brachytherapy source visualization, commissioning the source physical length for performing rotations, and using different planar and 3D window views to identify source orientation. Additional CivaSheet-specific tests were performed to determine the dosimetric influence on target coverage: changing the source tilt angle, source positioning in the treatment plan based on the CivaSheet rectangular array of CivaDots, and influence of prescription depth on the necessary treatment margin for adequate target coverage. Results: Higher imaging-resolution produced better accuracy for source orientation and positioning, with sub-millimeter CT slice-thickness and in-plane resolution preferred. Source rotation was possible only in sagittal or coronal views. The process for validating source orientation required iteratively altering rotations then checking them in the 3D view, which was cumbersome given the absence of quantitative plan documentation to indicate orientation. Given the small Pd-103 source size, influence of source tilt within 30° was negligible for <1.0 cm. Influence of source position was important when the source was positioned in/out of the adjacent source plane, causing changes of 15%, 7%, and 3% at depths of

Intra-operative 3D guidance and edema detection in prostate brachytherapy using a non-isocentric C-arm

PubMed Central

Jain, A.; Deguet, A.; Iordachita, I.; Chintalapani, G.; Vikal, S.; Blevins, J.; Le, Y.; Armour, E.; Burdette, C.; Song, D.; Fichtinger, G.

2015-01-01

Purpose Brachytherapy (radioactive seed insertion) has emerged as one of the most effective treatment options for patients with prostate cancer, with the added benefit of a convenient outpatient procedure. The main limitation in contemporary brachytherapy is faulty seed placement, predominantly due to the presence of intra-operative edema (tissue expansion). Though currently not available, the capability to intra-operatively monitor the seed distribution, can make a significant improvement in cancer control. We present such a system here. Methods Intra-operative measurement of edema in prostate brachytherapy requires localization of inserted radioactive seeds relative to the prostate. Seeds were reconstructed using a typical non-isocentric C-arm, and exported to a commercial brachytherapy treatment planning system. Technical obstacles for 3D reconstruction on a non-isocentric C-arm include pose-dependent C-arm calibration; distortion correction; pose estimation of C-arm images; seed reconstruction; and C-arm to TRUS registration. Results In precision-machined hard phantoms with 40–100 seeds and soft tissue phantoms with 45–87 seeds, we correctly reconstructed the seed implant shape with an average 3D precision of 0.35 mm and 0.24 mm, respectively. In a DoD Phase-1 clinical trial on six patients with 48–82 planned seeds, we achieved intra-operative monitoring of seed distribution and dosimetry, correcting for dose inhomogeneities by inserting an average of over four additional seeds in the six enrolled patients (minimum 1; maximum 9). Additionally, in each patient, the system automatically detected intra-operative seed migration induced due to edema (mean 3.84 mm, STD 2.13 mm, Max 16.19 mm). Conclusions The proposed system is the first of a kind that makes intra-operative detection of edema (and subsequent re-optimization) possible on any typical non-isocentric C-arm, at negligible additional cost to the existing clinical installation. It achieves a

Strength estimation of a moving 125Iodine source during implantation in brachytherapy: application to linked sources.

PubMed

Tanaka, Kenichi; Endo, Satoru; Tateoka, Kunihiko; Asanuma, Osamu; Hori, Masakazu; Takagi, Masaru; Bengua, Gerard; Kamo, Ken-Ichi; Sato, Kaori; Takeda, Hiromitsu; Hareyama, Masato; Sakata, Koh-Ichi; Takada, Jun

2014-11-01

This study sought to demonstrate the feasibility of estimating the source strength during implantation in brachytherapy. The requirement for measuring the strengths of the linked sources was investigated. The utilized sources were (125)I with air kerma strengths of 8.38-8.63 U (μGy m(2) h(-1)). Measurements were performed with a plastic scintillator (80 mm × 50 mm × 20 mm in thickness). For a source-to-source distance of 10.5 mm and at source speeds of up to 200 mm s(-1), a counting time of 10 ms and a detector-to-needle distance of 5 mm were found to be the appropriate measurement conditions. The combined standard uncertainty (CSU) with the coverage factor of 1 (k = 1) was ∼15% when using a grid to decrease the interference by the neighboring sources. Without the grid, the CSU (k = 1) was ∼5%, and an 8% overestimation due to the neighboring sources was found to potentially cause additional uncertainty. In order to improve the accuracy in estimating source strength, it is recommended that the measurment conditions should be optimized by considering the tradeoff between the overestimation due to the neighboring sources and the intensity of the measured value, which influences the random error. © The Author 2014. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology.

40 CFR 1027.125 - Can I get a refund?

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 32 2010-07-01 2010-07-01 false Can I get a refund? 1027.125 Section 1027.125 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS FEES FOR ENGINE, VEHICLE, AND EQUIPMENT COMPLIANCE PROGRAMS § 1027.125 Can I get a refund? (a) We will...

25 CFR 171.125 - Can I appeal BIA decisions?

Code of Federal Regulations, 2010 CFR

2010-04-01

... 25 Indians 1 2010-04-01 2010-04-01 false Can I appeal BIA decisions? 171.125 Section 171.125 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR LAND AND WATER IRRIGATION OPERATION AND MAINTENANCE General Provisions § 171.125 Can I appeal BIA decisions? (a) You may appeal our decisions in...

The dosimetry of brachytherapy-induced erectile dysfunction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Merrick, Gregory S.; Butler, Wayne M

2003-12-31

There is emerging evidence that brachytherapy-induced erectile dysfunction (ED) is technique-related and may be minimized by careful attention to source placement. Herein, we review the relationship between radiation doses to the prostate gland/surrounding structures and the development of brachytherapy-induced ED. The permanent prostate brachytherapy literature was reviewed using MEDLINE searches to ensure completeness. Although the site-specific structure associated with brachytherapy-induced ED remains unknown, there is an increasing body of data implicating the proximal penis. With day 0 CT-based dosimetry, the dose to 50% (D{sub 50}) and 25% (D{sub 25}) of the bulb of the penis should be maintained below 40%more » and 60% mPD, respectively, while the crura D{sub 50} should be maintained below 28% mPD to maximize post-brachytherapy potency. To date, there is no data to suggest that either radiation doses to the neurovascular bundles or choice of isotope is associated with brachytherapy-induced ED, while conflicting data has been reported regarding radiation dose to the prostate and the use of supplemental external beam radiation therapy. Although the etiology of brachytherapy-induced ED is likely multifactorial, the available data supports the proximal penis as an important site-specific structure. Refinements in implant technique, including preplanning and intraoperative seed placement, will result in lower radiation doses to the proximal penis with potential improvement in potency preservation.« less

Online gamma-camera imaging of 103Pd seeds (OGIPS) for permanent breast seed implantation

NASA Astrophysics Data System (ADS)

Ravi, Ananth; Caldwell, Curtis B.; Keller, Brian M.; Reznik, Alla; Pignol, Jean-Philippe

2007-09-01

Permanent brachytherapy seed implantation is being investigated as a mode of accelerated partial breast irradiation for early stage breast cancer patients. Currently, the seeds are poorly visualized during the procedure making it difficult to perform a real-time correction of the implantation if required. The objective was to determine if a customized gamma-camera can accurately localize the seeds during implantation. Monte Carlo simulations of a CZT based gamma-camera were used to assess whether images of suitable quality could be derived by detecting the 21 keV photons emitted from 74 MBq 103Pd brachytherapy seeds. A hexagonal parallel hole collimator with a hole length of 38 mm, hole diameter of 1.2 mm and 0.2 mm septa, was modeled. The design of the gamma-camera was evaluated on a realistic model of the breast and three layers of the seed distribution (55 seeds) based on a pre-implantation CT treatment plan. The Monte Carlo simulations showed that the gamma-camera was able to localize the seeds with a maximum error of 2.0 mm, using only two views and 20 s of imaging. A gamma-camera can potentially be used as an intra-procedural image guidance system for quality assurance for permanent breast seed implantation.

Dose verification of eye plaque brachytherapy using spectroscopic dosimetry.

PubMed

Jarema, T; Cutajar, D; Weaver, M; Petasecca, M; Lerch, M; Kejda, A; Rosenfeld, A

2016-09-01

Eye plaque brachytherapy has been developed and refined for the last 80 years, demonstrating effective results in the treatment of ocular malignancies. Current dosimetry techniques for eye plaque brachytherapy (such as TLD- and film-based techniques) are time consuming and cannot be used prior to treatment in a sterile environment. The measurement of the expected dose distribution within the eye, prior to insertion within the clinical setting, would be advantageous, as any errors in source loading will lead to an erroneous dose distribution and inferior treatment outcomes. This study investigated the use of spectroscopic dosimetry techniques for real-time quality assurance of I-125 based eye plaques, immediately prior to insertion. A silicon detector based probe, operating in spectroscopy mode was constructed, containing a small (1 mm(3)) silicon detector, mounted within a ceramic holder, all encapsulated within a rubber sheath to prevent water infiltration of the electronics. Preliminary tests of the prototype demonstrated that the depth dose distribution through the central axis of an I-125 based eye plaque may be determined from AAPM Task Group 43 recommendations to a deviation of 6 % at 3 mm depth, 7 % at 5 mm depth, 1 % at 10 mm depth and 13 % at 20 mm depth, with the deviations attributed to the construction of the probe. A new probe design aims to reduce these discrepancies, however the concept of spectroscopic dosimetry shows great promise for use in eye plaque quality assurance in the clinical setting.

Gold nanoparticle-aided brachytherapy with vascular dose painting: estimation of dose enhancement to the tumor endothelial cell nucleus.

PubMed

Ngwa, Wilfred; Makrigiorgos, G Mike; Berbeco, Ross I

2012-01-01

Theoretical microdosimetry at the subcellular level is employed in this study to estimate the dose enhancement to tumor endothelial cell nuclei, caused by radiation-induced photo/Auger electrons originating from gold nanoparticles (AuNPs) targeting the tumor endothelium, during brachytherapy. A tumor vascular endothelial cell (EC) is modeled as a slab of 2 μm (thickness) × 10 μm (length) × 10 μm (width). The EC contains a nucleus of 5 μm diameter and thickness of 0.5-1 μm, corresponding to nucleus size 5%-10% of cellular volume, respectively. Analytic calculations based on the electron energy loss formula of Cole were carried out to estimate the dose enhancement to the nucleus caused by photo/Auger electrons from AuNPs attached to the exterior surface of the EC. The nucleus dose enhancement factor (nDEF), representing the ratio of the dose to the nucleus with and without the presence of gold nanoparticles was calculated for different AuNP local concentrations. The investigated concentration range considers the potential for significantly higher local concentration near the EC due to preferential accumulation of AuNP in the tumor vasculature. Four brachytherapy sources: I-125, Pd-103, Yb-169, and 50 kVp x-rays were investigated. For nucleus size of 10% of the cellular volume and AuNP concentrations ranging from 7 to 140 mg/g, brachytherapy sources Pd-103, I-125, 50 kVp, and Yb-169 yielded nDEF values of 5.6-73, 4.8-58.3, 4.7-56.6, and 3.2-25.8, respectively. Meanwhile, for nucleus size 5% of the cellular volume in the same concentration range, Pd-103, I-125, 50 kVp, and Yb-169 yielded nDEF values of 6.9-79.2, 5.1-63.2, 5.0-61.5, and 3.3-28.3, respectively. The results predict that a substantial dose boost to the nucleus of endothelial cells can be achieved by applying tumor vasculature-targeted AuNPs in combination with brachytherapy. Such vascular dose boosts could induce tumor vascular shutdown, prompting extensive tumor cell death.

Dosimetric and radiobiological comparison of volumetric modulated arc therapy, high-dose rate brachytherapy, and low-dose rate permanent seeds implant for localized prostate cancer.

PubMed

Yang, Ruijie; Zhao, Nan; Liao, Anyan; Wang, Hao; Qu, Ang

2016-01-01

To investigate the dosimetric and radiobiological differences among volumetric modulated arc therapy (VMAT), high-dose rate (HDR) brachytherapy, and low-dose rate (LDR) permanent seeds implant for localized prostate cancer. A total of 10 patients with localized prostate cancer were selected for this study. VMAT, HDR brachytherapy, and LDR permanent seeds implant plans were created for each patient. For VMAT, planning target volume (PTV) was defined as the clinical target volume plus a margin of 5mm. Rectum, bladder, urethra, and femoral heads were considered as organs at risk. A 78Gy in 39 fractions were prescribed for PTV. For HDR and LDR plans, the dose prescription was D90 of 34Gy in 8.5Gy per fraction, and 145Gy to clinical target volume, respectively. The dose and dose volume parameters were evaluated for target, organs at risk, and normal tissue. Physical dose was converted to dose based on 2-Gy fractions (equivalent dose in 2Gy per fraction, EQD2) for comparison of 3 techniques. HDR and LDR significantly reduced the dose to rectum and bladder compared with VMAT. The Dmean (EQD2) of rectum decreased 22.36Gy in HDR and 17.01Gy in LDR from 30.24Gy in VMAT, respectively. The Dmean (EQD2) of bladder decreased 6.91Gy in HDR and 2.53Gy in LDR from 13.46Gy in VMAT. For the femoral heads and normal tissue, the mean doses were also significantly reduced in both HDR and LDR compared with VMAT. For the urethra, the mean dose (EQD2) was 80.26, 70.23, and 104.91Gy in VMAT, HDR, and LDR brachytherapy, respectively. For localized prostate cancer, both HDR and LDR brachytherapy were clearly superior in the sparing of rectum, bladder, femoral heads, and normal tissue compared with VMAT. HDR provided the advantage in sparing of urethra compared with VMAT and LDR. Copyright © 2016 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

Dosimetric and radiobiological comparison of volumetric modulated arc therapy, high-dose rate brachytherapy, and low-dose rate permanent seeds implant for localized prostate cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Ruijie, E-mail: ruijyang@yahoo.com; Zhao, Nan; Liao, Anyan

To investigate the dosimetric and radiobiological differences among volumetric modulated arc therapy (VMAT), high-dose rate (HDR) brachytherapy, and low-dose rate (LDR) permanent seeds implant for localized prostate cancer. A total of 10 patients with localized prostate cancer were selected for this study. VMAT, HDR brachytherapy, and LDR permanent seeds implant plans were created for each patient. For VMAT, planning target volume (PTV) was defined as the clinical target volume plus a margin of 5 mm. Rectum, bladder, urethra, and femoral heads were considered as organs at risk. A 78 Gy in 39 fractions were prescribed for PTV. For HDR andmore » LDR plans, the dose prescription was D{sub 90} of 34 Gy in 8.5 Gy per fraction, and 145 Gy to clinical target volume, respectively. The dose and dose volume parameters were evaluated for target, organs at risk, and normal tissue. Physical dose was converted to dose based on 2-Gy fractions (equivalent dose in 2 Gy per fraction, EQD{sub 2}) for comparison of 3 techniques. HDR and LDR significantly reduced the dose to rectum and bladder compared with VMAT. The D{sub mean} (EQD{sub 2}) of rectum decreased 22.36 Gy in HDR and 17.01 Gy in LDR from 30.24 Gy in VMAT, respectively. The D{sub mean} (EQD{sub 2}) of bladder decreased 6.91 Gy in HDR and 2.53 Gy in LDR from 13.46 Gy in VMAT. For the femoral heads and normal tissue, the mean doses were also significantly reduced in both HDR and LDR compared with VMAT. For the urethra, the mean dose (EQD{sub 2}) was 80.26, 70.23, and 104.91 Gy in VMAT, HDR, and LDR brachytherapy, respectively. For localized prostate cancer, both HDR and LDR brachytherapy were clearly superior in the sparing of rectum, bladder, femoral heads, and normal tissue compared with VMAT. HDR provided the advantage in sparing of urethra compared with VMAT and LDR.« less

A Spanner in the works: the use of a new temporary urethral stent to relieve bladder outflow obstruction after prostate brachytherapy.

PubMed

Henderson, Alastair; Laing, Robert W; Langley, Stephen E M

2002-01-01

Assessment of the Spanner, a new temporary urethral stent to relieve bladder outflow obstruction and urinary symptoms after brachytherapy. Five patients with unusually severe urinary morbidity after (125)I brachytherapy were recruited. The mean time after implant was 40 days (range 25-90). Spanner intraprostatic stents were introduced using topical anesthetic without complication. All patients were able to void spontaneously with no post-void residual volume of urine. The flow rates increased in all cases (p=0.03) and the International Prostate Symptom Scores were significantly improved after stent insertion in all patients (p=0.03). All patients experienced some degree of pain or dysuria during stent use. Bladder outflow obstruction was effectively treated with the Spanner intraprostatic stent, however pain limited the use of the device in the early post-brachytherapy patient group. Pharmacotherapy, stent design modification, or smaller stent diameter may increase the utility of stents after brachytherapy.

Effect of photon energy spectrum on dosimetric parameters of brachytherapy sources.

PubMed

Ghorbani, Mahdi; Mehrpouyan, Mohammad; Davenport, David; Ahmadi Moghaddas, Toktam

2016-06-01

The aim of this study is to quantify the influence of the photon energy spectrum of brachytherapy sources on task group No. 43 (TG-43) dosimetric parameters. Different photon spectra are used for a specific radionuclide in Monte Carlo simulations of brachytherapy sources. MCNPX code was used to simulate 125I, 103Pd, 169Yb, and 192Ir brachytherapy sources. Air kerma strength per activity, dose rate constant, radial dose function, and two dimensional (2D) anisotropy functions were calculated and isodose curves were plotted for three different photon energy spectra. The references for photon energy spectra were: published papers, Lawrence Berkeley National Laboratory (LBNL), and National Nuclear Data Center (NNDC). The data calculated by these photon energy spectra were compared. Dose rate constant values showed a maximum difference of 24.07% for 103Pd source with different photon energy spectra. Radial dose function values based on different spectra were relatively the same. 2D anisotropy function values showed minor differences in most of distances and angles. There was not any detectable difference between the isodose contours. Dosimetric parameters obtained with different photon spectra were relatively the same, however it is suggested that more accurate and updated photon energy spectra be used in Monte Carlo simulations. This would allow for calculation of reliable dosimetric data for source modeling and calculation in brachytherapy treatment planning systems.

Effect of metal ions on the enzymatic hydrolysis of hemp seed oil by lipase Candida sp. 99-125.

PubMed

Lu, Jike; Wang, Pei; Ke, Zhaodi; Liu, Xin; Kang, Qiaozhen; Hao, Limin

2018-07-15

In order to study the effect of metal ions on the enzymatic hydrolysis of hemp seed oil by Candida sp. 99-125, the spectroscopy, stability and hydrolytic activity of the biocatalyst were investigated in presence of Ca 2+ , Mg 2+ , Fe 2+ , Fe 3+ , Cu 2+ , Sn 2+ , Pb 2+ , Zn 2+ and Ba 2+ metal ions, respectively. The UV spectroscopy showed that all the metal ions enhanced the absorbance but the decrease of fluorescence intensity was observed. All the metal ions could improve the lipase thermal stability except Cu 2+ and Ba 2+ . Hydrolysis of hemp seed oil proved that Ca 2+ , Fe 3+ , Pb 2+ and Ba 2+ could significantly improve the hydrolytic rate, and metal ions could influence lipase selectivity. The study revealed that metal ions could improve lipase stability, hydrolysis activity in the hydrolytic process of hemp seed oil by Candida sp. 99-125. Copyright © 2018 Elsevier B.V. All rights reserved.

BrachyView: Combining LDR seed positions with transrectal ultrasound imaging in a prostate gel phantom.

PubMed

Alnaghy, S; Cutajar, D L; Bucci, J A; Enari, K; Safavi-Naeini, M; Favoino, M; Tartaglia, M; Carriero, F; Jakubek, J; Pospisil, S; Lerch, M; Rosenfeld, A B; Petasecca, M

2017-02-01

BrachyView is a novel in-body imaging system which aims to provide LDR brachytherapy seeds position reconstruction within the prostate in real-time. The first prototype is presented in this study: the probe consists of a gamma camera featuring three single cone pinhole collimators embedded in a tungsten tube, above three, high resolution pixelated detectors (Timepix). The prostate was imaged with a TRUS system using a sagittal crystal with a 2.5mm slice thickness. Eleven needles containing a total of thirty 0.508U 125 I seeds were implanted under ultrasound guidance. A CT scan was used to localise the seed positions, as well as provide a reference when performing the image co-registration between the BrachyView coordinate system and the TRUS coordinate system. An in-house visualisation software interface was developed to provide a quantitative 3D reconstructed prostate based on the TRUS images and co-registered with the LDR seeds in situ. A rigid body image registration was performed between the BrachyView and TRUS systems, with the BrachyView and CT-derived source locations compared. The reconstructed seed positions determined by the BrachyView probe showed a maximum discrepancy of 1.78mm, with 75% of the seeds reconstructed within 1mm of their nominal location. An accurate co-registration between the BrachyView and TRUS coordinate system was established. The BrachyView system has shown its ability to reconstruct all implanted LDR seeds within a tissue equivalent prostate gel phantom, providing both anatomical and seed position information in a single interface. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

Monte Carlo study of a new I‐125 brachytherapy prototype seed with a ceramic radionuclide carrier and radiographic marker

PubMed Central

Paixão, Lucas; Santos, Ana Maria M.; dos Santos, Adriano Márcio; Grynberg, Suely Epsztein

2012-01-01

In prostate cancer treatment, there is an increasing interest in the permanent radioactive seeds implant technique. Currently, in Brazil, the seeds are imported with high prices, which prohibit their use in public hospitals. A ceramic matrix that can be used as a radioisotope carrier and radiographic marker was developed at our institution. The ceramic matrix is distinguished by the characteristic of maintaining the radioactive material uniformly distributed in its surface. In this work, Monte Carlo simulations were performed in order to assess the dose distributions generated by this prototype seed model, with the ceramic matrix encapsulated in titanium, in the same way as the commercial 6711 seed. The obtained data was assessed, as described in the TG‐43U1 report by the American Association of Physicists in Medicine, for two seed models: (1) the most used model 6711 source — for validation and comparison, and (2) for the prototype model with the ceramic matrix. The dosimetric parameters dose rate constant, Λ, radial dose function, gL(r), and anisotropy function, F(r,θ), were derived from simulations by the Monte Carlo method using the MCNP5 code. A Λ 0.992 (±2.33%) cGyh−1U−1 was found for the prototype model. In comparison with the 6711 model, a lower dose fall‐off on transverse axis was found, as well as a lower dose anisotropy for the radius r= 0.25 cm. In general, for all distances, the prototype seed model presents a slightly larger anisotropy between 0° ≤ Θ < 50° and anisotropy similar to the 6711 model for Θ ≥ 50°. The dosimetric characteristics of the prototype model presented in this study suggest that its use is feasible. Because of the model's characteristics, seeds of lower specific activity iodine might be necessary which, on the other hand, would help to reduce costs. However, it has to be emphasized that the proposed source is a prototype, and the required (AAPM prerequisites) experimental study and tolerance

Intra-operative 3D guidance in prostate brachytherapy using a non-isocentric C-arm.

PubMed

Jain, A; Deguet, A; Iordachita, I; Chintalapani, G; Blevins, J; Le, Y; Armour, E; Burdette, C; Song, D; Fichtinger, G

2007-01-01

Intra-operative guidance in Transrectal Ultrasound (TRUS) guided prostate brachytherapy requires localization of inserted radioactive seeds relative to the prostate. Seeds were reconstructed using a typical C-arm, and exported to a commercial brachytherapy system for dosimetry analysis. Technical obstacles for 3D reconstruction on a non-isocentric C-arm included pose-dependent C-arm calibration; distortion correction; pose estimation of C-arm images; seed reconstruction; and C-arm to TRUS registration. In precision-machined hard phantoms with 40-100 seeds, we correctly reconstructed 99.8% seeds with a mean 3D accuracy of 0.68 mm. In soft tissue phantoms with 45-87 seeds and clinically realistic 15 degrees C-arm motion, we correctly reconstructed 100% seeds with an accuracy of 1.3 mm. The reconstructed 3D seed positions were then registered to the prostate segmented from TRUS. In a Phase-1 clinical trial, so far on 4 patients with 66-84 seeds, we achieved intra-operative monitoring of seed distribution and dosimetry. We optimized the 100% prescribed iso-dose contour by inserting an average of 3.75 additional seeds, making intra-operative dosimetry possible on a typical C-arm, at negligible additional cost to the existing clinical installation.

125-mJ diode-pumped injection-seeded Ho:Tm:YLF laser.

PubMed

Yu, J; Singh, U N; Barnes, N P; Petros, M

1998-05-15

We describe a diode-pumped, room-temperature Ho:Tm:YLF power oscillator with an optical-to-optical efficiency of 0.03. A Q -switched output energy of as much as 125 mJ at 6 Hz with a pulse width of 170 ns was obtained. Single-frequency, nearly transform-limited operation of the laser was achieved by injection seeding. Laser performance as a function of laser rod temperature and pump intensity was also investigated. The high power and high beam quality of this laser make it well suited for use as a coherent wind lidar transmitter on a space platform.

Intra-operative Localization of Brachytherapy Implants Using Intensity-based Registration

PubMed Central

KarimAghaloo, Z.; Abolmaesumi, P.; Ahmidi, N.; Chen, T.K.; Gobbi, D. G.; Fichtinger, G.

2010-01-01

In prostate brachytherapy, a transrectal ultrasound (TRUS) will show the prostate boundary but not all the implanted seeds, while fluoroscopy will show all the seeds clearly but not the boundary. We propose an intensity-based registration between TRUS images and the implant reconstructed from uoroscopy as a means of achieving accurate intra-operative dosimetry. The TRUS images are first filtered and compounded, and then registered to the uoroscopy model via mutual information. A training phantom was implanted with 48 seeds and imaged. Various ultrasound filtering techniques were analyzed, and the best results were achieved with the Bayesian combination of adaptive thresholding, phase congruency, and compensation for the non-uniform ultrasound beam profile in the elevation and lateral directions. The average registration error between corresponding seeds relative to the ground truth was 0.78 mm. The effect of false positives and false negatives in ultrasound were investigated by masking true seeds in the uoroscopy volume or adding false seeds. The registration error remained below 1.01 mm when the false positive rate was 31%, and 0.96 mm when the false negative rate was 31%. This fully automated method delivers excellent registration accuracy and robustness in phantom studies, and promises to demonstrate clinically adequate performance on human data as well. Keywords: Prostate brachytherapy, Ultrasound, Fluoroscopy, Registration. PMID:21152376

Automated seed localization from CT datasets of the prostate.

PubMed

Brinkmann, D H; Kline, R W

1998-09-01

With the increasing utilization of permanent brachytherapy implants for treating carcinoma of the prostate, the importance of accurate post-treatment dose calculation also increases for assessing patient outcome and planning future treatments. An automatic method for seed localization of permanent brachytherapy implants, using CT datasets of the prostate, has been developed and tested on a phantom using an actual patient planned seed distribution. This method was also compared to results with the three-film technique for three patient datasets. The automatic method is as accurate or more accurate than the three film technique for 1 mm, 3 mm, and 5 mm contiguous CT slices, and eliminates the inter- and intra-observer variability of the manual methods. The automated method improves the localization of brachytherapy seeds while reducing the time required for the user to input information, and is demonstrated to be less operator dependent, less time consuming, and potentially more accurate than the three-film technique.

Development of an adjoint sensitivity field-based treatment-planning technique for the use of newly designed directional LDR sources in brachytherapy.

PubMed

Chaswal, V; Thomadsen, B R; Henderson, D L

2012-02-21

The development and application of an automated 3D greedy heuristic (GH) optimization algorithm utilizing the adjoint sensitivity fields for treatment planning to assess the advantage of directional interstitial prostate brachytherapy is presented. Directional and isotropic dose kernels generated using Monte Carlo simulations based on Best Industries model 2301 I-125 source are utilized for treatment planning. The newly developed GH algorithm is employed for optimization of the treatment plans for seven interstitial prostate brachytherapy cases using mixed sources (directional brachytherapy) and using only isotropic sources (conventional brachytherapy). All treatment plans resulted in V100 > 98% and D90 > 45 Gy for the target prostate region. For the urethra region, the D10(Ur), D90(Ur) and V150(Ur) and for the rectum region the V100cc, D2cc, D90(Re) and V90(Re) all are reduced significantly when mixed sources brachytherapy is used employing directional sources. The simulations demonstrated that the use of directional sources in the low dose-rate (LDR) brachytherapy of the prostate clearly benefits in sparing the urethra and the rectum sensitive structures from overdose. The time taken for a conventional treatment plan is less than three seconds, while the time taken for a mixed source treatment plan is less than nine seconds, as tested on an Intel Core2 Duo 2.2 GHz processor with 1GB RAM. The new 3D GH algorithm is successful in generating a feasible LDR brachytherapy treatment planning solution with an extra degree of freedom, i.e. directionality in very little time.

Development of an adjoint sensitivity field-based treatment-planning technique for the use of newly designed directional LDR sources in brachytherapy

NASA Astrophysics Data System (ADS)

Chaswal, V.; Thomadsen, B. R.; Henderson, D. L.

2012-02-01

The development and application of an automated 3D greedy heuristic (GH) optimization algorithm utilizing the adjoint sensitivity fields for treatment planning to assess the advantage of directional interstitial prostate brachytherapy is presented. Directional and isotropic dose kernels generated using Monte Carlo simulations based on Best Industries model 2301 I-125 source are utilized for treatment planning. The newly developed GH algorithm is employed for optimization of the treatment plans for seven interstitial prostate brachytherapy cases using mixed sources (directional brachytherapy) and using only isotropic sources (conventional brachytherapy). All treatment plans resulted in V100 > 98% and D90 > 45 Gy for the target prostate region. For the urethra region, the D10Ur, D90Ur and V150Ur and for the rectum region the V100cc, D2cc, D90Re and V90Re all are reduced significantly when mixed sources brachytherapy is used employing directional sources. The simulations demonstrated that the use of directional sources in the low dose-rate (LDR) brachytherapy of the prostate clearly benefits in sparing the urethra and the rectum sensitive structures from overdose. The time taken for a conventional treatment plan is less than three seconds, while the time taken for a mixed source treatment plan is less than nine seconds, as tested on an Intel Core2 Duo 2.2 GHz processor with 1GB RAM. The new 3D GH algorithm is successful in generating a feasible LDR brachytherapy treatment planning solution with an extra degree of freedom, i.e. directionality in very little time.

Comparison of TG-43 dosimetric parameters of brachytherapy sources obtained by three different versions of MCNP codes.

PubMed

Zaker, Neda; Zehtabian, Mehdi; Sina, Sedigheh; Koontz, Craig; Meigooni, Ali S

2016-03-08

Monte Carlo simulations are widely used for calculation of the dosimetric parameters of brachytherapy sources. MCNP4C2, MCNP5, MCNPX, EGS4, EGSnrc, PTRAN, and GEANT4 are among the most commonly used codes in this field. Each of these codes utilizes a cross-sectional library for the purpose of simulating different elements and materials with complex chemical compositions. The accuracies of the final outcomes of these simulations are very sensitive to the accuracies of the cross-sectional libraries. Several investigators have shown that inaccuracies of some of the cross section files have led to errors in 125I and 103Pd parameters. The purpose of this study is to compare the dosimetric parameters of sample brachytherapy sources, calculated with three different versions of the MCNP code - MCNP4C, MCNP5, and MCNPX. In these simulations for each source type, the source and phantom geometries, as well as the number of the photons, were kept identical, thus eliminating the possible uncertainties. The results of these investigations indicate that for low-energy sources such as 125I and 103Pd there are discrepancies in gL(r) values. Discrepancies up to 21.7% and 28% are observed between MCNP4C and other codes at a distance of 6 cm for 103Pd and 10 cm for 125I from the source, respectively. However, for higher energy sources, the discrepancies in gL(r) values are less than 1.1% for 192Ir and less than 1.2% for 137Cs between the three codes.

On-line I-/Te- separation for the AMS analysis of 125I

NASA Astrophysics Data System (ADS)

Charles, C. R. J.; Cornett, R. J.; Zhao, X.-L.; Litherland, A. E.; Kieser, W. E.

2015-10-01

The isobar separator for anions (ISA) was used together with a 3 MV tandem accelerator mass spectrometer (AMS) to demonstrate the real time (on-line) separation of Te- from I-. Following the ion source mass spectrometry and major retardation to tens of eV, the ISA uses a radiofrequency quadrupole (RFQ) ion guide to confine and direct I- and associated Te- isobar anions through a gas-reaction cell, where chemical reactions occur at eV energies with the electronegative gas NO2. Anions are subsequently reaccelerated out of the ISA to near original ion source extraction energies for AMS analysis. At 5 mTorr NO2 in the ISA gas-reaction cell, 125Te- was observed to be attenuated by a factor of ∼107 as compared to 127I- that did not experience significant (<50%) losses. A comparative test using 37Cl- and 32S- (having similar chemical properties to iodine and tellurium) showed a 32S- attenuation of >107 relative to 37Cl- under the same ISA-AMS conditions. The preferential destruction of Te- (and S-) at eV energies in the ISA is likely due to a larger favorable destruction cross-section with NO2. This study is the first demonstration of I-Te anion separation for AMS, and makes possible the use of 125I, free of the contaminant 125Te isobar after suitable sample purification, for future 129I/125I carrier-free analyses of natural samples at ultra-low trace levels.

A fully actuated robotic assistant for MRI-guided prostate biopsy and brachytherapy

NASA Astrophysics Data System (ADS)

Li, Gang; Su, Hao; Shang, Weijian; Tokuda, Junichi; Hata, Nobuhiko; Tempany, Clare M.; Fischer, Gregory S.

2013-03-01

Intra-operative medical imaging enables incorporation of human experience and intelligence in a controlled, closed-loop fashion. Magnetic resonance imaging (MRI) is an ideal modality for surgical guidance of diagnostic and therapeutic procedures, with its ability to perform high resolution, real-time, high soft tissue contrast imaging without ionizing radiation. However, for most current image-guided approaches only static pre-operative images are accessible for guidance, which are unable to provide updated information during a surgical procedure. The high magnetic field, electrical interference, and limited access of closed-bore MRI render great challenges to developing robotic systems that can perform inside a diagnostic high-field MRI while obtaining interactively updated MR images. To overcome these limitations, we are developing a piezoelectrically actuated robotic assistant for actuated percutaneous prostate interventions under real-time MRI guidance. Utilizing a modular design, the system enables coherent and straight forward workflow for various percutaneous interventions, including prostate biopsy sampling and brachytherapy seed placement, using various needle driver configurations. The unified workflow compromises: 1) system hardware and software initialization, 2) fiducial frame registration, 3) target selection and motion planning, 4) moving to the target and performing the intervention (e.g. taking a biopsy sample) under live imaging, and 5) visualization and verification. Phantom experiments of prostate biopsy and brachytherapy were executed under MRI-guidance to evaluate the feasibility of the workflow. The robot successfully performed fully actuated biopsy sampling and delivery of simulated brachytherapy seeds under live MR imaging, as well as precise delivery of a prostate brachytherapy seed distribution with an RMS accuracy of 0.98mm.

In vivo fate of 125I SS-B (La) injected into mice.

PubMed Central

Schrieber, L; Erhardt, C C; Melsom, R D; Venables, P J; McCarthy, D A; Mumford, P A; Horsfall, A C; Maini, R N

1983-01-01

The fate of the radiolabelled soluble cellular antigen SS-B (La) was compared with that of other 125I-labelled proteins of known molecular weight (MW) and electrostatic charge, following i.v. injection into BALB/c mice. The plasma half-life of 125I-SS-B was 3 min, while that of 125I-bovine serum albumin (similar MW and electrostatic charge) was 270 min. 125I-heat-aggregated IgG (MW greater than 1 x 10(6)) and 125I-7S human IgG (MW 168,000) had plasma half-lives of 40 min and greater than 300 min, respectively. Liver and kidney showed preferential uptake of 125I-SS-B, followed by a rapid decrease in radioactivity. During this time low MW, trichloroacetic acid (TCA) soluble, material appeared in urine. This suggests a specific uptake mechanism followed by a catabolic phase. These studies demonstrate that normal mice remove 125I-SS-B rapidly from the circulation and then degrade it. This rapid antigen elimination may protect against the induction of potentially harmful autoantibody responses. PMID:6832805

Effect of photon energy spectrum on dosimetric parameters of brachytherapy sources

PubMed Central

Ghorbani, Mahdi; Davenport, David

2016-01-01

Abstract Aim The aim of this study is to quantify the influence of the photon energy spectrum of brachytherapy sources on task group No. 43 (TG-43) dosimetric parameters. Background Different photon spectra are used for a specific radionuclide in Monte Carlo simulations of brachytherapy sources. Materials and methods MCNPX code was used to simulate 125I, 103Pd, 169Yb, and 192Ir brachytherapy sources. Air kerma strength per activity, dose rate constant, radial dose function, and two dimensional (2D) anisotropy functions were calculated and isodose curves were plotted for three different photon energy spectra. The references for photon energy spectra were: published papers, Lawrence Berkeley National Laboratory (LBNL), and National Nuclear Data Center (NNDC). The data calculated by these photon energy spectra were compared. Results Dose rate constant values showed a maximum difference of 24.07% for 103Pd source with different photon energy spectra. Radial dose function values based on different spectra were relatively the same. 2D anisotropy function values showed minor differences in most of distances and angles. There was not any detectable difference between the isodose contours. Conclusions Dosimetric parameters obtained with different photon spectra were relatively the same, however it is suggested that more accurate and updated photon energy spectra be used in Monte Carlo simulations. This would allow for calculation of reliable dosimetric data for source modeling and calculation in brachytherapy treatment planning systems. PMID:27247558

A systematic evaluation of the dose-rate constant determined by photon spectrometry for 21 different models of low-energy photon-emitting brachytherapy sources.

PubMed

Chen, Zhe Jay; Nath, Ravinder

2010-10-21

The aim of this study was to perform a systematic comparison of the dose-rate constant (Λ) determined by the photon spectrometry technique (PST) with the consensus value ((CON)Λ) recommended by the American Association of Physicists in Medicine (AAPM) for 21 low-energy photon-emitting interstitial brachytherapy sources. A total of 63 interstitial brachytherapy sources (21 different models with 3 sources per model) containing either (125)I (14 models), (103)Pd (6 models) or (131)Cs (1 model) were included in this study. A PST described by Chen and Nath (2007 Med. Phys. 34 1412-30) was used to determine the dose-rate constant ((PST)Λ) for each source model. Source-dependent variations in (PST)Λ were analyzed systematically against the spectral characteristics of the emitted photons and the consensus values recommended by the AAPM brachytherapy subcommittee. The values of (PST)Λ for the encapsulated sources of (103)Pd, (125)I and (131)Cs varied from 0.661 to 0.678 cGyh(-1) U(-1), 0.959 to 1.024 cGyh(-1)U(-1) and 1.066 to 1.073 cGyh(-1)U(-1), respectively. The relative variation in (PST)Λ among the six (103)Pd source models, caused by variations in photon attenuation and in spatial distributions of radioactivity among the source models, was less than 3%. Greater variations in (PST)Λ were observed among the 14 (125)I source models; the maximum relative difference was over 6%. These variations were caused primarily by the presence of silver in some (125)I source models and, to a lesser degree, by the variations in photon attenuation and in spatial distribution of radioactivity among the source models. The presence of silver generates additional fluorescent x-rays with lower photon energies which caused the (PST)Λ value to vary from 0.959 to 1.019 cGyh(-1)U(-1) depending on the amount of silver used by a given source model. For those (125)I sources that contain no silver, their (PST)Λ was less variable and had values within 1% of 1.024 cGyh(-1)U(-1). For the 16

High Intensity Focused Ultrasound (HIFU) as a Salvage Treatment for Recurrent Prostate Cancer after Brachytherapy — a Feasibility Study

NASA Astrophysics Data System (ADS)

Chapman, Alexander T.; Rivens, Ian H.; Thompson, Alan C.; ter Haar, Gail R.

2007-05-01

HIFU may be an effective salvage treatment for patients who develop local recurrence after permanent low-dose brachytherapy. It has been suggested that the presence of seeds in the prostate may obstruct the HIFU beam or alter the heating characteristics of the prostate tissue. Acoustic field measurements were made using a membrane hydrophone and lesioning experiments were carried out in ex vivo bovine liver. These revealed a significant effect of the seeds on the HIFU focal region as well as a reduction in lesion length when seeds were placed in a pre-focal position. Further work is needed to evaluate the full effects of implanted brachytherapy seeds on the clinical delivery of HIFU.

SU-E-T-301: Dosimetric Comparison Between Adaptive and Rectilinear Template-Based Prostate Seed Implants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sugar, E Neubauer; Buzurovic, I; O’Farrell, D

2015-06-15

Purpose: To compare the dosimetry of a standard rectilinear and an adaptive technique used in I125 prostate seed implants. Methods: To achieve favorable dosimetry in prostate implants we used adaptive needle updates to match actual positions in real-time. The seed locations were optimized based on actual needle locations. The seeds were delivered automatically with a robotic device seedSelectron™ (Elekta Brachytherapy). In this study, we evaluated the former approach against the standard rectilinear technique in which the needles have a parallel distribution. The treatment plans for 10 patients were analyzed. For comparison, the actual treatment plans were revised so each needlemore » was repositioned to its original parallel location through the template. The analysis was performed by comparing the target coverage and dose to the organs at risk. The comparison was done using the following planning goals: the target D90> 90%, V100% > 90%, V50% <70% and V200% <30%; the urethra V125% < 1cm3 and V150%= 0cm3; and the Rectum V100%<1cm3 and V69% < 8cm3. The prescription dose to the target was 145Gy. Results: The average target volume and number of seeds were 44.39cm3(SD=11.14) and 74(SD=12), respectively. The D90 for adaptive and rectilinear plans was 159.9Gy(SD=2.99) and 155.53Gy(SD=4.04) resulting in a 2.74% difference for the average target coverage. A similar difference (1.75%) was noticed in the target V100[%]. No significant difference was noticed in the dose to the urethra and rectum. All planning goals were met with both the adaptive and rectilinear approach for each plan. Conclusion: The study reveals enhanced coverage of the target when using the adaptive needle adjustments as compared to the rectilinear approach for the analyzed cases. However, the differences in dosimetry did not translate to meaningful clinical outcomes.« less

Survey of brachytherapy practice in the United States: a report of the Clinical Research Committee of the American Endocurietherapy Society.

PubMed

Nag, S; Owen, J B; Farnan, N; Pajak, T F; Martinez, A; Porter, A; Blasko, J; Harrison, L B

1995-01-01

To obtain reliable data on the extent of the brachytherapy practice in the United States by conducting a comprehensive survey of all facilities. The Clinical Research Committee of the AES surveyed all 1321 radiation oncology facilities identified in the Patterns of Care Study (PCS) of the American College of Radiology (ACR). Multiple mailings and follow-up were made to obtain a high response rate. Survey responders and nonresponders were compared using chi-square tests. Summary statistics were reported. Of the 1321 facilities, 1054 responded (80%). Hospital-based and larger facilities had a statistically significant higher rate of response. Brachytherapy was being performed at 819 facilities (the median number of procedures = 21-50). Two hundred and two facilities did no brachytherapy. The common isotopes used were 137Cs (705 facilities), 192Ir (585 facilities), 125I (236 facilities), and 131I (194 facilities). The common brachytherapy techniques used were intracavitary (751 facilities), interstitial (536 facilities), intraluminal (310 facilities), and plaques (148 facilities). Remote afterloaded brachytherapy was used at 205 centers as follows: high dose rate (HDR) (164), medium dose rate (MDR) (5), and low dose rate (LDR) (36). Computerized dosimetry was most commonly used (790 facilities), followed by Patterson-Parker (104 facilities) and Quimby (72 facilities). The common sites treated were cervix (701 facilities), endometrium (565 facilities), head and neck (354 facilities), and lung (344 facilities). Data regarding brachytherapy practice has been obtained from a large percentage (80%) of all facilities in the United States. The majority (78-81%) of radiation oncology facilities perform brachytherapy; however, its use is restricted to gynecological implants in many of these centers. The results from this survey will be used to develop a pattern of care study and data registry in brachytherapy.

Dose reduction in LDR brachytherapy by implanted prostate gold fiducial markers.

PubMed

Landry, Guillaume; Reniers, Brigitte; Lutgens, Ludy; Murrer, Lars; Afsharpour, Hossein; de Haas-Kock, Danielle; Visser, Peter; van Gils, Francis; Verhaegen, Frank

2012-03-01

The dosimetric impact of gold fiducial markers (FM) implanted prior to external beam radiotherapy of prostate cancer on low dose rate (LDR) brachytherapy seed implants performed in the context of combined therapy was investigated. A virtual water phantom was designed containing a single FM. Single and multi source scenarios were investigated by performing Monte Carlo dose calculations, along with the influence of varying orientation and distance of the FM with respect to the sources. Three prostate cancer patients treated with LDR brachytherapy for a recurrence following external beam radiotherapy with implanted FM were studied as surrogate cases to combined therapy. FM and brachytherapy seeds were identified on post implant CT scans and Monte Carlo dose calculations were performed with and without FM. The dosimetric impact of the FM was evaluated by quantifying the amplitude of dose shadows and the volume of cold spots. D(90) was reported based on the post implant CT prostate contour. Large shadows are observed in the single source-FM scenarios. As expected from geometric considerations, the shadows are dependent on source-FM distance and orientation. Large dose reductions are observed at the distal side of FM, while at the proximal side a dose enhancement is observed. In multisource scenarios, the importance of shadows appears mitigated, although FM at the periphery of the seed distribution caused underdosage (brachytherapy seed implant dose distributions. Therefore, reduced tumor control could be expected from FM implanted in tumors, although our results are too limited to draw conclusions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muryn, J; Wilkinson, D

Purpose: The purpose of this work is to evaluate a method for confirming source strength of I-125 seeds in a bulk assay while maintaining sterility and time efficiency. Methods: The I-125 seeds used in this study (STM 1251, Bard Brachytherapy, Inc.) were available as loose seeds or linked in 3, 4, or 5 seed configurations. A third party 10% assay (NIST traceable) is provided. Source strengths ranging from 0.395 to 0.504 U were available for this study. A stand was built out of aluminum to hold an exposure meter (Inovision (Fluke) 451P) at 25 cm above the I-125 sources tomore » measure the exposure rate. Three different seed configurations were measured: loose, linked, and loaded needles (Bard FastFil Seed Implant Needle). The measurements were made in an operating room, and a sterile sheet was used under the non-sterile aluminum stand. Seeds and needles were placed in a sterile tray. Results: One hundred forty-two loose seeds in 5 batches (0.395, 0.395, 0.409, 0.444, 0.444 U/seed) and 902 seeds in 7 batches containing various strands (0.444, 0.444,.0444, 0.466, 0.466, 0.504, 0.504 U/seed) were measured. The average exposure rate per unit activity was measured to be 0.593 mR per hr per U with a standard deviation of 0.016. The Result for loaded needles was 0.261 mR per hr per U with a standard deviation of 0.014. Once the apparatus is set up, measurements of 180 linked sources as supplied in the Bard package requires only a few minutes. Conclusion: The proposed method can confirm the activity of a batch of loose or stranded I-125 seeds within a range of 5%.« less

[Degradation of prolactin 125-I in the mammary gland of lactating rats].

PubMed

Marinchenko, G V; Taranenko, A G

1977-01-01

Prolactin-125I metabolism in the mammary gland of lactating rats was studied; the hormone was injected intraperitoneally. Radioactive products accumulated by the mammary gland tissue were extracted with isotonic medium. Tissue extracts, blood serum and milk were analyzed by gel filtration on Sephadex G-200. The Blood displayed a gradual reduction of prolactin-125I content as a result of its splitting in the organs and binding with blood proteins; as to the mammary gland--there occurred accumulation of the products of prolactin-125I degradation. Some hormone was inactivated losing immunological properties without any significant changes in the molecular weight. Besides, the mammary gland displayed an intensive accumulation of the products of prolactin-125I splitting in the other organs and in the gland proper. Radioactivity accumulated in the milk was mainly referred to the products of prolactin-125I degradation. There was also shown the presence of immunologically active prolactin-125I in the milk.

Calculated and measured brachytherapy dosimetry parameters in water for the Xoft Axxent X-Ray Source: an electronic brachytherapy source.

PubMed

Rivard, Mark J; Davis, Stephen D; DeWerd, Larry A; Rusch, Thomas W; Axelrod, Steve

2006-11-01

. Excluding an energy response function, measurements of normalized photon energy spectra were made for three operating voltages, and were typically within 2% agreement with the normalized Monte Carlo calculated spectra. In general, the model S700 Source exhibited depth dose behavior similar to low-energy photon-emitting low dose rate sources 125I and l03Pd, yet with capability for variable and much higher dose rates and subsequently adjustable penetration capabilities. This paper presents the calculated and measured in-water brachytherapy dosimetry parameters for the model S700 Source at the aforementioned three operating voltages.

Evaluation of water-mimicking solid phantom materials for use in HDR and LDR brachytherapy dosimetry

NASA Astrophysics Data System (ADS)

Schoenfeld, Andreas A.; Thieben, Maike; Harder, Dietrich; Poppe, Björn; Chofor, Ndimofor

2017-12-01

In modern HDR or LDR brachytherapy with photon emitters, fast checks of the dose profiles generated in water or a water-equivalent phantom have to be available in the interest of patient safety. However, the commercially available brachytherapy photon sources cover a wide range of photon emission spectra, and the range of the in-phantom photon spectrum is further widened by Compton scattering, so that the achievement of water-mimicking properties of such phantoms involves high requirements on their atomic composition. In order to classify the degree of water equivalence of the numerous commercially available solid water-mimicking phantom materials and the energy ranges of their applicability, the radial profiles of the absorbed dose to water, D w, have been calculated using Monte Carlo simulations in these materials and in water phantoms of the same dimensions. This study includes the HDR therapy sources Nucletron Flexisource Co-60 HDR (60Co), Eckert und Ziegler BEBIG GmbH CSM-11 (137Cs), Implant Sciences Corporation HDR Yb-169 Source 4140 (169Yb) as well as the LDR therapy sources IsoRay Inc. Proxcelan CS-1 (131Cs), IsoAid Advantage I-125 IAI-125A (125I), and IsoAid Advantage Pd-103 IAPd-103A (103Pd). Thereby our previous comparison between phantom materials and water surrounding a Varian GammaMed Plus HDR therapy 192Ir source (Schoenfeld et al 2015) has been complemented. Simulations were performed in cylindrical phantoms consisting of either water or the materials RW1, RW3, Solid Water, HE Solid Water, Virtual Water, Plastic Water DT, Plastic Water LR, Original Plastic Water (2015), Plastic Water (1995), Blue Water, polyethylene, polystyrene and PMMA. While for 192Ir, 137Cs and 60Co most phantom materials can be regarded as water equivalent, for 169Yb the materials Plastic Water LR, Plastic Water DT and RW1 appear as water equivalent. For the low-energy sources 106Pd, 131Cs and 125I, only Plastic Water LR can be classified as water equivalent.

Evaluation of water-mimicking solid phantom materials for use in HDR and LDR brachytherapy dosimetry.

PubMed

Schoenfeld, Andreas A; Thieben, Maike; Harder, Dietrich; Poppe, Björn; Chofor, Ndimofor

2017-11-21

In modern HDR or LDR brachytherapy with photon emitters, fast checks of the dose profiles generated in water or a water-equivalent phantom have to be available in the interest of patient safety. However, the commercially available brachytherapy photon sources cover a wide range of photon emission spectra, and the range of the in-phantom photon spectrum is further widened by Compton scattering, so that the achievement of water-mimicking properties of such phantoms involves high requirements on their atomic composition. In order to classify the degree of water equivalence of the numerous commercially available solid water-mimicking phantom materials and the energy ranges of their applicability, the radial profiles of the absorbed dose to water, D w , have been calculated using Monte Carlo simulations in these materials and in water phantoms of the same dimensions. This study includes the HDR therapy sources Nucletron Flexisource Co-60 HDR ( 60 Co), Eckert und Ziegler BEBIG GmbH CSM-11 ( 137 Cs), Implant Sciences Corporation HDR Yb-169 Source 4140 ( 169 Yb) as well as the LDR therapy sources IsoRay Inc. Proxcelan CS-1 ( 131 Cs), IsoAid Advantage I-125 IAI-125A ( 125 I), and IsoAid Advantage Pd-103 IAPd-103A ( 103 Pd). Thereby our previous comparison between phantom materials and water surrounding a Varian GammaMed Plus HDR therapy 192 Ir source (Schoenfeld et al 2015) has been complemented. Simulations were performed in cylindrical phantoms consisting of either water or the materials RW1, RW3, Solid Water, HE Solid Water, Virtual Water, Plastic Water DT, Plastic Water LR, Original Plastic Water (2015), Plastic Water (1995), Blue Water, polyethylene, polystyrene and PMMA. While for 192 Ir, 137 Cs and 60 Co most phantom materials can be regarded as water equivalent, for 169 Yb the materials Plastic Water LR, Plastic Water DT and RW1 appear as water equivalent. For the low-energy sources 106 Pd, 131 Cs and 125 I, only Plastic Water LR can be classified as water

Comparison of TG‐43 dosimetric parameters of brachytherapy sources obtained by three different versions of MCNP codes

PubMed Central

Zaker, Neda; Sina, Sedigheh; Koontz, Craig; Meigooni1, Ali S.

2016-01-01

Monte Carlo simulations are widely used for calculation of the dosimetric parameters of brachytherapy sources. MCNP4C2, MCNP5, MCNPX, EGS4, EGSnrc, PTRAN, and GEANT4 are among the most commonly used codes in this field. Each of these codes utilizes a cross‐sectional library for the purpose of simulating different elements and materials with complex chemical compositions. The accuracies of the final outcomes of these simulations are very sensitive to the accuracies of the cross‐sectional libraries. Several investigators have shown that inaccuracies of some of the cross section files have led to errors in  125I and  103Pd parameters. The purpose of this study is to compare the dosimetric parameters of sample brachytherapy sources, calculated with three different versions of the MCNP code — MCNP4C, MCNP5, and MCNPX. In these simulations for each source type, the source and phantom geometries, as well as the number of the photons, were kept identical, thus eliminating the possible uncertainties. The results of these investigations indicate that for low‐energy sources such as  125I and  103Pd there are discrepancies in gL(r) values. Discrepancies up to 21.7% and 28% are observed between MCNP4C and other codes at a distance of 6 cm for  103Pd and 10 cm for  125I from the source, respectively. However, for higher energy sources, the discrepancies in gL(r) values are less than 1.1% for  192Ir and less than 1.2% for  137Cs between the three codes. PACS number(s): 87.56.bg PMID:27074460

Dependence with air density of the response of the PTW SourceCheck ionization chamber for low energy brachytherapy sources.

PubMed

Tornero-López, Ana M; Guirado, Damián; Perez-Calatayud, Jose; Ruiz-Arrebola, Samuel; Simancas, Fernando; Gazdic-Santic, Maja; Lallena, Antonio M

2013-12-01

Air-communicating well ionization chambers are commonly used to assess air kerma strength of sources used in brachytherapy. The signal produced is supposed to be proportional to the air density within the chamber and, therefore, a density-independent air kerma strength is obtained when the measurement is corrected to standard atmospheric conditions using the usual temperature and pressure correction factor. Nevertheless, when assessing low energy sources, the ionization chambers may not fulfill that condition and a residual density dependence still remains after correction. In this work, the authors examined the behavior of the PTW 34051 SourceCheck ionization chamber when measuring the air kerma strength of (125)I seeds. Four different SourceCheck chambers were analyzed. With each one of them, two series of measurements of the air kerma strength for (125)I selectSeed(TM) brachytherapy sources were performed inside a pressure chamber and varying the pressure in a range from 747 to 1040 hPa (560 to 780 mm Hg). The temperature and relative humidity were kept basically constant. An analogous experiment was performed by taking measurements at different altitudes above sea level. Contrary to other well-known ionization chambers, like the HDR1000 PLUS, in which the temperature-pressure correction factor overcorrects the measurements, in the SourceCheck ionization chamber they are undercorrected. At a typical atmospheric situation of 933 hPa (700 mm Hg) and 20 °C, this undercorrection turns out to be 1.5%. Corrected measurements show a residual linear dependence on the density and, as a consequence, an additional density dependent correction must be applied. The slope of this residual linear density dependence is different for each SourceCheck chamber investigated. The results obtained by taking measurements at different altitudes are compatible with those obtained with the pressure chamber. Variations of the altitude and changes in the weather conditions may produce

An experimental palladium-103 seed (OptiSeed{sup exp}) in a biocompatible polymer without a gold marker: Characterization of dosimetric parameters including the interseed effect

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abboud, F.; Scalliet, P.; Vynckier, S.

Permanent implantation of {sup 125}I (iodine) or {sup 103}Pd (palladium) sources is a popular treatment option in the management of early stage prostate cancer. New sources are being developed, some of which are being marketed for different clinical applications. A new technique of adjuvant stereotactic permanent seed breast implant, similar to that used in the treatment of prostate cancer, has been proposed by [N. Jansen et al., Int. J. Radiat. Oncol. Biol. Phys. 67, 1052-1058 (2007)] with encouraging results. The presence of artifacts from the metallic seeds, however, can disturb follow-up imaging. The development of plastic seeds has reduced thesemore » artifacts. This paper presents a feasibility study of the advantages of palladium-103 seeds, encapsulated with a biocompatible polymer, for future clinical applications, and on the effect of the gold marker on the dosimetric characteristics of such seeds. Experimental palladium seeds, OptiSeed{sup exp}, were manufactured by International Brachytherapy (IBt), Seneffe, Belgium, from a biocompatible polymer, including the marker. Apart from the absence of a gold marker, the studied seed has an identical design to the OptiSeed{sup 103}[Phys. Med. Biol. 50, 1493-1504 (2005)]; [Appl. Radiat. Isot. 63, 311-321 (2005)]. Polymer encapsulation was preferred by IBt in order to reduce the quantity of radioactive material needed for a given dose rate and to reduce the anisotropy of the radiation field around the seed. In addition, this design is intended to decrease the interseed effects that can occur as a result of the marker and the encapsulation. Dosimetric measurements were performed using LiF thermoluminescent dosimeters (1 mm{sup 3}) in solid water phantoms (WT1). Measured data were compared to Monte Carlo simulated data in solid water using the MCNP code, version 4C. Updated cross sections [Med. Phys. 30, 701-711 (2003)] were used. As the measured and calculated data were in agreement, Monte Carlo calculations were

LDR brachytherapy: can low dose rate hypersensitivity from the "inverse" dose rate effect cause excessive cell killing to peripherial connective tissues and organs?

PubMed

Leonard, B E; Lucas, A C

2009-02-01

Examined here are the possible effects of the "inverse" dose rate effect (IDRE) on low dose rate (LDR) brachytherapy. The hyper-radiosensitivity and induced radioresistance (HRS/IRR) effect benefits cell killing in radiotherapy, and IDRE and HRS/IRR seem to be generated from the same radioprotective mechanisms. We have computed the IDRE excess cell killing experienced in LDR brachytherapy using permanent seed implants. We conclude, firstly, that IDRE is a dose rate-dependent manifestation of HRS/IRR. Secondly, the presence of HRS/IRR or IDRE in a cell species or tissue must be determined by direct dose-response measurements. Thirdly, a reasonable estimate is that 50-80% of human adjoining connective and organ tissues experience IDRE from permanent implanted LDR brachytherapy. If IDRE occurs for tissues at point A for cervical cancer, the excess cell killing will be about a factor of 3.5-4.0 if the initial dose rate is 50-70 cGy h(-1). It is greater for adjacent tissues at lower dose rates and higher for lower initial dose rates at point A. Finally, higher post-treatment complications are observed in LDR brachytherapy, often for unknown reasons. Some of these are probably a result of IDRE excess cell killing. Measurements of IDRE need be performed for connective and adjacent organ tissues, i.e. bladder, rectum, urinary tract and small bowels. The measured dose rate-dependent dose responses should extended to <10 cGy h(-1) and involve multiple patients to detect patient variability. Results may suggest a preference for high dose rate brachytherapy or LDR brachytherapy without permanent retention of the implant seeds (hence the dose rates in peripheral tissues and organs remain above IDRE thresholds).

Salvage/Adjuvant Brachytherapy After Ophthalmic Artery Chemosurgery for Intraocular Retinoblastoma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Francis, Jasmine H., E-mail: francij1@mskcc.org; Barker, Christopher A.; Wolden, Suzanne L.

2013-11-01

Purpose: To evaluate the efficacy and toxicity of brachytherapy after ophthalmic artery chemosurgery (OAC) for retinoblastoma. Methods and Materials: This was a single-arm, retrospective study of 15 eyes in 15 patients treated with OAC followed by brachytherapy at (blinded institution) between May 1, 2006, and December 31, 2012, with a median 19 months' follow-up from plaque insertion. Outcome measurements included patient and ocular survival, visual function, and retinal toxicity measured by electroretinogram (ERG). Results: Brachytherapy was used as adjuvant treatment in 2 eyes and as salvage therapy in 13 eyes of which 12 had localized vitreous seeding. No patients developedmore » metastasis or died of retinoblastoma. The Kaplan-Meier estimate of ocular survival was 79.4% (95% confidence interval 48.7%-92.8%) at 18 months. Three eyes were enucleated, and an additional 6 eyes developed out-of-target volume recurrences, which were controlled with additional treatments. Patients with an ocular complication had a mean interval between last OAC and plaque of 2.5 months (SD 2.3 months), which was statistically less (P=.045) than patients without ocular complication who had a mean interval between last OAC and plaque of 6.5 months (SD 4.4 months). ERG responses from pre- versus postplaque were unchanged or improved in more than half the eyes. Conclusions: Brachytherapy following OAC is effective, even in the presence of vitreous seeding; the majority of eyes maintained stable or improved retinal function following treatment, as assessed by ERG.« less

33 CFR 159.125 - Visible floating solids: Type I devices.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Visible floating solids: Type I devices. 159.125 Section 159.125 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION MARINE SANITATION DEVICES Design, Construction, and Testing § 159.125...

Characterization of Low-Energy Photon-Emitting Brachytherapy Sources with Modified Strengths for Applications in Focal Therapy

NASA Astrophysics Data System (ADS)

Reed, Joshua L.

Permanent implants of low-energy photon-emitting brachytherapy sources are used to treat a variety of cancers. Individual source models must be separately characterized due to their unique geometry, materials, and radionuclides, which all influence their dose distributions. Thermoluminescent dosimeters (TLDs) are often used for dose measurements around low-energy photon-emitting brachytherapy sources. TLDs are typically calibrated with higher energy sources such as 60Co, which requires a correction for the change in the response of the TLDs as a function of photon energy. These corrections have historically been based on TLD response to x ray bremsstrahlung spectra instead of to brachytherapy sources themselves. This work determined the TLD intrinsic energy dependence for 125I and 103Pd sources relative to 60Co, which allows for correction of TLD measurements of brachytherapy sources with factors specific to their energy spectra. Traditional brachytherapy sources contain mobile internal components and large amounts of high-Z material such as radio-opaque markers and titanium encapsulations. These all contribute to perturbations and uncertainties in the dose distribution around the source. The CivaString is a new elongated 103Pd brachytherapy source with a fixed internal geometry, polymer encapsulation, and lengths ranging from 1 to 6 cm, which offers advantages over traditional source designs. This work characterized the CivaString source and the results facilitated the formal approval of this source for use in clinical treatments. Additionally, the accuracy of a superposition technique for dose calculation around the sources with lengths >1 cm was verified. Advances in diagnostic techniques are paving the way for focal brachytherapy in which the dose is intentionally modulated throughout the target volume to focus on subvolumes that contain cancer cells. Brachytherapy sources with variable longitudinal strength (VLS) are a promising candidate for use in focal

Applying gold nanoparticles as tumor-vascular disrupting agents during brachytherapy: estimation of endothelial dose enhancement

NASA Astrophysics Data System (ADS)

Ngwa, Wilfred; Makrigiorgos, G. Mike; Berbeco, Ross I.

2010-11-01

Tumor vascular disrupting agents (VDAs) represent a promising approach to the treatment of cancer, in view of the tumor vasculature's pivotal role in tumor survival, growth and metastasis. VDAs targeting the tumor's dysmorphic endothelial cells can cause selective and rapid occlusion of the tumor vasculature, leading to tumor cell death from ischemia and extensive hemorrhagic necrosis. In this study, the potential for applying gold nanoparticles (AuNPs) as VDAs, during brachytherapy, is examined. Analytic calculations based on the electron energy loss formula of Cole were carried out to estimate the endothelial dose enhancement caused by radiation-induced photo/Auger electrons originating from AuNPs targeting the tumor endothelium. The endothelial dose enhancement factor (EDEF), representing the ratio of the dose to the endothelium with and without gold nanoparticles was calculated for different AuNP local concentrations, and endothelial cell thicknesses. Four brachytherapy sources were investigated, I-125, Pd-103, Yb-169, as well as 50 kVp x-rays. The results reveal that, even at relatively low intra-vascular AuNP concentrations, ablative dose enhancement to tumor endothelial cells due to photo/Auger electrons from the AuNPs can be achieved. Pd-103 registered the highest EDEF values of 7.4-271.5 for local AuNP concentrations ranging from 7 to 350 mg g-1, respectively. Over the same concentration range, I-125, 50 kVp and Yb-169 yielded values of 6.4-219.9, 6.3-214.5 and 4.0-99.7, respectively. Calculations of the EDEF as a function of endothelial cell thickness showed that lower energy sources like Pd-103 reach the maximum EDEF at smaller thicknesses. The results also reveal that the highest contribution to the EDEF comes from Auger electrons, apparently due to their shorter range. Overall, the data suggest that ablative dose enhancement to tumor endothelial cells can be achieved by applying tumor vasculature-targeted AuNPs as adjuvants to brachytherapy, with lower

SU-E-T-212: Comparison of TG-43 Dosimetric Parameters of Low and High Energy Brachytherapy Sources Obtained by MCNP Code Versions of 4C, X and 5

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zehtabian, M; Zaker, N; Sina, S

2015-06-15

Purpose: Different versions of MCNP code are widely used for dosimetry purposes. The purpose of this study is to compare different versions of the MCNP codes in dosimetric evaluation of different brachytherapy sources. Methods: The TG-43 parameters such as dose rate constant, radial dose function, and anisotropy function of different brachytherapy sources, i.e. Pd-103, I-125, Ir-192, and Cs-137 were calculated in water phantom. The results obtained by three versions of Monte Carlo codes (MCNP4C, MCNPX, MCNP5) were compared for low and high energy brachytherapy sources. Then the cross section library of MCNP4C code was changed to ENDF/B-VI release 8 whichmore » is used in MCNP5 and MCNPX codes. Finally, the TG-43 parameters obtained using the MCNP4C-revised code, were compared with other codes. Results: The results of these investigations indicate that for high energy sources, the differences in TG-43 parameters between the codes are less than 1% for Ir-192 and less than 0.5% for Cs-137. However for low energy sources like I-125 and Pd-103, large discrepancies are observed in the g(r) values obtained by MCNP4C and the two other codes. The differences between g(r) values calculated using MCNP4C and MCNP5 at the distance of 6cm were found to be about 17% and 28% for I-125 and Pd-103 respectively. The results obtained with MCNP4C-revised and MCNPX were similar. However, the maximum difference between the results obtained with the MCNP5 and MCNP4C-revised codes was 2% at 6cm. Conclusion: The results indicate that using MCNP4C code for dosimetry of low energy brachytherapy sources can cause large errors in the results. Therefore it is recommended not to use this code for low energy sources, unless its cross section library is changed. Since the results obtained with MCNP4C-revised and MCNPX were similar, it is concluded that the difference between MCNP4C and MCNPX is their cross section libraries.« less

Place of modern imaging in brachytherapy planning.

PubMed

Hellebust, T P

2018-06-01

Imaging has probably been the most important driving force for the development of brachytherapy treatments the last 20 years. Due to implementation of three-dimensional imaging, brachytherapy is nowadays a highly accurate and reliable treatment option for many cancer patients. To be able to optimize the dose distribution in brachytherapy the anatomy and the applicator(s) or sources should be correctly localised in the images. For computed tomography (CT) the later criteria is easily fulfilled for most brachytherapy sites. However, for many sites, like cervix and prostate, CT is not optimal for delineation since soft tissue is not adequately visualized and the tumor is not well discriminated. For cervical cancer treatment planning based on magnetic resonance imaging (MRI) is recommended. Some centres also use MRI for postimplant dosimetry of permanent prostate seed implant and high dose rate prostate brachytherapy. Moreover, in so called focal brachytherapy where only a part of the prostate is treated, multiparametric MRI is an excellent tool that can assist in defining the target volume. Applicator or source localization is challenging using MRI, but tolls exist to assist this process. Also, geometrical distortions should be corrected or accounted for. Transrectal ultrasound is considered to be the gold standard for high dose rate prostate brachytherapy and transrectal ultrasound -based brachytherapy procedure offers a method for interactive treatment planning. Reconstruction of the needles is sometimes challenging, especially to identify the needle tip. The accuracy of the reconstruction could be improved by measuring the residuals needle length and by using a bi-planar transducer. The last decade several groups worldwide have explored the use of transrectal and transabdominal ultrasound for cervical cancer brachytherapy. Since ultrasonography is widely available, offers fast image acquisition and is a rather inexpensive modality such development is interesting

The evolution of brachytherapy for prostate cancer.

PubMed

Zaorsky, Nicholas G; Davis, Brian J; Nguyen, Paul L; Showalter, Timothy N; Hoskin, Peter J; Yoshioka, Yasuo; Morton, Gerard C; Horwitz, Eric M

2017-06-30

Brachytherapy (BT), using low-dose-rate (LDR) permanent seed implantation or high-dose-rate (HDR) temporary source implantation, is an acceptable treatment option for select patients with prostate cancer of any risk group. The benefits of HDR-BT over LDR-BT include the ability to use the same source for other cancers, lower operator dependence, and - typically - fewer acute irritative symptoms. By contrast, the benefits of LDR-BT include more favourable scheduling logistics, lower initial capital equipment costs, no need for a shielded room, completion in a single implant, and more robust data from clinical trials. Prospective reports comparing HDR-BT and LDR-BT to each other or to other treatment options (such as external beam radiotherapy (EBRT) or surgery) suggest similar outcomes. The 5-year freedom from biochemical failure rates for patients with low-risk, intermediate-risk, and high-risk disease are >85%, 69-97%, and 63-80%, respectively. Brachytherapy with EBRT (versus brachytherapy alone) is an appropriate approach in select patients with intermediate-risk and high-risk disease. The 10-year rates of overall survival, distant metastasis, and cancer-specific mortality are >85%, <10%, and <5%, respectively. Grade 3-4 toxicities associated with HDR-BT and LDR-BT are rare, at <4% in most series, and quality of life is improved in patients who receive brachytherapy compared with those who undergo surgery.

Favorable toxicity and biochemical control using real-time inverse optimization technique for prostate brachytherapy.

PubMed

Raben, Adam; Rusthoven, Kyle E; Sarkar, Abrihup; Glick, Andrew; Benge, Bruce; Jacobs, Dayee; Raben, David

2009-01-01

Favorable dosimetric results have been reported using intraoperative inverse optimization (IO) for permanent prostate brachytherapy. The clinical implications of these improvements in dosimetry are unclear. We review toxicity and early biochemical outcomes for patients implanted using IO technique. Between 2001 and 2007, 165 patients received permanent prostate implants using real-time IO and had >/=3 months of followup. Dose constraints for inverse planning were: the prostate volume receiving 100% of the prescription dose [prostate V(100)] was >95%; the dose received by 90% of the gland [prostate D(90)] was within the 140-180 by dose range; the volume of urethra receiving 150% of the prescription dose [urethra V(150)] was <30%; and the volume of rectal wall receiving 110% of the prescription dose [rectal V(110)] was <1.0 cc. Toxicity was prospectively scored using the Radiation Therapy Oncology Group toxicity scale and the International Prostate Symptom Score questionnaire. Biochemical control was determined using the nadir + 2 ng/mL definition. Mean followup was 30 months (range, 6-63 months). Risk classification was low risk in 89% and intermediate risk in 11%. Iodine-125 sources were used for 161 implants and palladium-103 sources for four implants. The median number of seeds and total activity implanted were 61 and 999 MBq, respectively, for a median prostate volume of 33.6 cc. Late GU and GI morbidity was uncommon. Among patients with at least 24 months followup, 16% had persistent Grade 2-3 urinary morbidity. Grade 2 rectal bleeding occurred in 1 patient (0.6%). Biochemical failure has occurred in only 4 patients at last followup. IO technique for prostate brachytherapy is associated with low rates of late morbidity and excellent early biochemical control. Additionally, the number of seeds and total implanted activity required to achieve a high-quality implant are lower compared with historical controls.

Brachytherapy for cervix cancer: low-dose rate or high-dose rate brachytherapy – a meta-analysis of clinical trials

PubMed Central

Viani, Gustavo A; Manta, Gustavo B; Stefano, Eduardo J; de Fendi, Ligia I

2009-01-01

Background The literature supporting high-dose rate brachytherapy (HDR) in the treatment of cervical carcinoma derives primarily from retrospective series. However, controversy still persists regarding the efficacy and safety of HDR brachytherapy compared to low-dose rate (LDR) brachytherapy, in particular, due to inadequate tumor coverage for stage III patients. Whether LDR or HDR brachytherapy produces better results for these patients in terms of survival rate, local control rate and the treatment complications remain controversial. Methods A meta-analysis of RCT was performed comparing LDR to HDR brachytherapy for cervix cancer treated for radiotherapy alone. The MEDLINE, EMBASE, CANCERLIT and Cochrane Library databases, as well as abstracts published in the annual proceedings were systematically searched. We assessed methodological quality for each outcome by grading the quality of evidence using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology. We used "recommend" for strong recommendations, and "suggest" for weak recommendations. Results Pooled results from five randomized trials (2,065 patients) of HDR brachytherapy in cervix cancer showed no significant increase of mortality (p = 0.52), local recurrence (p = 0.68), or late complications (rectal; p = 0.7, bladder; p = 0.95 or small intestine; p = 0.06) rates as compared to LDR brachytherapy. In the subgroup analysis no difference was observed for overall mortality and local recurrence in patients with clinical stages I, II and III. The quality of evidence was low for mortality and local recurrence in patients with clinical stage I, and moderate for other clinical stages. Conclusion Our meta-analysis shows that there are no differences between HDR and LDR for overall survival, local recurrence and late complications for clinical stages I, II and III. By means of the GRADE system, we recommend the use of HDR for all clinical stages of cervix cancer. PMID:19344527

A survey of current clinical practice in permanent and temporary prostate brachytherapy: 2010 update.

PubMed

Buyyounouski, Mark K; Davis, Brian J; Prestidge, Bradley R; Shanahan, Thomas G; Stock, Richard G; Grimm, Peter D; Demanes, D Jeffrey; Zaider, Marco; Horwitz, Eric M

2012-01-01

To help establish patterns of care and standards of care of interstitial permanent low-dose-rate (LDR) and temporary high-dose-rate brachytherapy for prostate cancer and to compare the results with a similar 1998 American Brachytherapy Society (ABS) survey. A comprehensive questionnaire intended to survey specific details of current clinical brachytherapy practice was provided to the participants of the seventh ABS Prostate Brachytherapy School. Responses were tabulated and descriptive statistics are reported. Sixty-five brachytherapy practitioners responded to the survey. Eighty-nine percent (89%) of respondents performed LDR and 49% perform high-dose-rate brachytherapy. The median number of years of experience for LDR brachytherapists increased from 5 to 10 years over the course of the 12 years since the preceding survey. Compared with the first ABS, a smaller proportion of respondents received formal brachytherapy residency training (43% vs. 56%) or formal "hands-on" brachytherapy training (15% vs. 63%). There has been a marked decline in the utilization of the Mick applicator (Mick Radio-Nuclear Instruments, Inc., Mount Vernon, NY, USA) (60% vs. 28%) and an increase in the use of stranded seeds (40% vs. 11%). Compliance with postimplant dosimetry was higher in the 2010 survey. This survey does suggest an evolution in the practice of LDR brachytherapy since 1998 and aids in identifying aspects that require further progress or investigation. ABS guidelines and other practice recommendations appear to impact the practice of brachytherapy. Copyright © 2012 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

Solid-phase receptor binding assay for /sup 125/I-hCG

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bortolussi, M.; Selmin, O.; Colombatti, A.

1987-01-01

A solid-phase radioligand-receptor assay (RRA) to measure the binding of /sup 125/I-labelled human chorionic gonadotropin (/sup 125/I-hCG) to target cell membranes has been developed. The binding of /sup 125/I-hCG to membranes immobilized on the wells of microtitration plates reached a maximum at about 3 hours at 37 degrees C, was saturable, displayed a high affinity (Ka = 2.4 X 10(9) M-1) and was specifically inhibited by unlabelled hCG. In comparison with RRAs carried out with membranes in suspension, the solid-phase RRA is significantly simpler and much faster to perform as it avoids centrifugation or filtration procedures. The solid-phase RRA wasmore » adapted profitably to process large numbers of samples at the same time. It proved particularly useful as a screening assay to detect anti-hCG monoclonal antibodies with high inhibitory activity for binding of /sup 125/I-hCG to its receptors.« less

WE-E-BRD-01: HDR Brachytherapy I: Overview of Clinical Application and QA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Libby, B; Showalter, T

2014-06-15

With the increased usage of high dose rate (HDR) brachytherapy and the introduction of dedicated image guided brachytherapy suites, it is necessary to review the processes and procedures associated with safely delivering these treatments in the expedited time scales that dedicated treatment suites afford. The speakers will present the clinical aspects of switching from LDR to HDR treatments, including guidelines for patient selection, and the clinical outcomes comparing LDR to HDR. The speakers will also discuss the HDR treatment process itself, because the shortened clinical timeline involved with a streamlined scan/plan/treat workflow can introduce other issues. Safety and QA aspectsmore » involved with the streamlined process, including increased personnel required for parallel tasks, and possible interfering tasks causing delays in patient treatments will also be discussed. Learning Objectives: To understand the clinical aspects of HDR Brachytherapy, including common clinical indications, patient selection, and the evolving evidence in support of this therapeutic modality To review the current prominent clinical trials for HDR brachytherapy To interpret the established guidelines for HDR brachytherapy quality assurance for implementation into practical clinical settings. To introduce the basic requirements for image guided brachytherapy.« less

Sexual Function and the use of Medical Devices or Drugs to Optimize Potency after Prostate Brachytherapy

PubMed Central

Whaley, J. Taylor; Levy, Lawrence B.; Swanson, David A.; Pugh, Thomas J.; Kudchadker, Rajat J.; Bruno, Teresa L.; Frank, Steven J.

2013-01-01

Purpose Prospective evaluation of sexual outcomes after prostate brachytherapy with iodine-125 seeds as monotherapy at a tertiary cancer care center. Methods and Materials Subjects were 129 men with prostate cancer with I-125 seed implants (prescribed dose, 145 Gy) without supplemental hormonal or external beam radiation therapy. Sexual function, potency, and bother were prospectively assessed at baseline and at 1, 4, 8, and 12 months using validated quality-of-life self-assessment surveys. Postimplant dosimetry values, including dose to 10% of the penile bulb (D10), D20, D33, D50, D75, D90, and penile-volume receiving 100% of the prescribed dose (V100) were calculated. Results At baseline, 56% of patients recorded having optimal erections; at 1 year, 62% of patients with baseline erectile function maintained optimal potency, 58% of whom with medically prescribed sexual aids or drugs. Variables associated with pretreatment-to-posttreatment decline in potency were time after implant (p=0.04) and age (p=0.01). Decline in urinary function may have been related to decline in potency. At 1 year, 69% of potent patients younger than 70 years maintained optimal potency, whereas 31% of patients over 70 maintained optimal potency (p=0.02). Diabetes was related to a decline in potency (p=0.05), but neither smoking nor hypertension were. For patients with optimal potency at baseline, mean sexual bother scores had declined significantly at 1 year (p<0.01). Sexual potency, sexual function, and sexual bother scores failed to correlate with any dosimetric variable tested. Conclusions Erections firm enough for intercourse can be achieved at 1 year after treatment, but most men will require medical aids to optimize potency. Although younger men were better able to maintain erections firm enough for intercourse than older men, there was no correlation between potency, sexual function, or sexual bother and penile bulb dosimetry. PMID:22300559

Sexual function and the use of medical devices or drugs to optimize potency after prostate brachytherapy.

PubMed

Whaley, J Taylor; Levy, Lawrence B; Swanson, David A; Pugh, Thomas J; Kudchadker, Rajat J; Bruno, Teresa L; Frank, Steven J

2012-04-01

Prospective evaluation of sexual outcomes after prostate brachytherapy with iodine-125 seeds as monotherapy at a tertiary cancer care center. Subjects were 129 men with prostate cancer with I-125 seed implants (prescribed dose, 145 Gy) without supplemental hormonal or external beam radiation therapy. Sexual function, potency, and bother were prospectively assessed at baseline and at 1, 4, 8, and 12 months using validated quality-of-life self-assessment surveys. Postimplant dosimetry values, including dose to 10% of the penile bulb (D10), D20, D33, D50, D75, D90, and penile volume receiving 100% of the prescribed dose (V100) were calculated. At baseline, 56% of patients recorded having optimal erections; at 1 year, 62% of patients with baseline erectile function maintained optimal potency, 58% of whom with medically prescribed sexual aids or drugs. Variables associated with pretreatment-to-posttreatment decline in potency were time after implant (p = 0.04) and age (p = 0.01). Decline in urinary function may have been related to decline in potency. At 1 year, 69% of potent patients younger than 70 years maintained optimal potency, whereas 31% of patients older than 70 maintained optimal potency (p = 0.02). Diabetes was related to a decline in potency (p = 0.05), but neither smoking nor hypertension were. For patients with optimal potency at baseline, mean sexual bother scores had declined significantly at 1 year (p < 0.01). Sexual potency, sexual function, and sexual bother scores failed to correlate with any dosimetric variable tested. Erections firm enough for intercourse can be achieved at 1 year after treatment, but most men will require medical aids to optimize potency. Although younger men were better able to maintain erections firm enough for intercourse than older men, there was no correlation between potency, sexual function, or sexual bother and penile bulb dosimetry. Copyright © 2012 Elsevier Inc. All rights reserved.

Sexual Function and the Use of Medical Devices or Drugs to Optimize Potency After Prostate Brachytherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Whaley, J. Taylor; Levy, Lawrence B.; Swanson, David A.

Purpose: Prospective evaluation of sexual outcomes after prostate brachytherapy with iodine-125 seeds as monotherapy at a tertiary cancer care center. Methods and Materials: Subjects were 129 men with prostate cancer with I-125 seed implants (prescribed dose, 145 Gy) without supplemental hormonal or external beam radiation therapy. Sexual function, potency, and bother were prospectively assessed at baseline and at 1, 4, 8, and 12 months using validated quality-of-life self-assessment surveys. Postimplant dosimetry values, including dose to 10% of the penile bulb (D10), D20, D33, D50, D75, D90, and penile volume receiving 100% of the prescribed dose (V100) were calculated. Results: Atmore » baseline, 56% of patients recorded having optimal erections; at 1 year, 62% of patients with baseline erectile function maintained optimal potency, 58% of whom with medically prescribed sexual aids or drugs. Variables associated with pretreatment-to-posttreatment decline in potency were time after implant (p = 0.04) and age (p = 0.01). Decline in urinary function may have been related to decline in potency. At 1 year, 69% of potent patients younger than 70 years maintained optimal potency, whereas 31% of patients older than 70 maintained optimal potency (p = 0.02). Diabetes was related to a decline in potency (p = 0.05), but neither smoking nor hypertension were. For patients with optimal potency at baseline, mean sexual bother scores had declined significantly at 1 year (p < 0.01). Sexual potency, sexual function, and sexual bother scores failed to correlate with any dosimetric variable tested. Conclusions: Erections firm enough for intercourse can be achieved at 1 year after treatment, but most men will require medical aids to optimize potency. Although younger men were better able to maintain erections firm enough for intercourse than older men, there was no correlation between potency, sexual function, or sexual bother and penile bulb dosimetry.« less

Long reach DWDM-PON with 12.5 GHz channel spacing based on comb source seeding

NASA Astrophysics Data System (ADS)

Zhou, Zhao; Nie, Hai-tao; Wang, Yao-jun

2016-07-01

A long reach dense wavelength division multiplexing passive optical network (DWDM-PON) with 12.5 GHz channel spacing is proposed and experimentally demonstrated. An optical frequency comb source is used to provide the multiwavelength seeding light, while reflective semiconductor optical amplifiers (RSOAs) are installed in both optical line terminal (OLT) and optical network units (ONUs) as colorless transmitter. The experimental results show that the bidirectional transmission for 1.2 Gbit/s data rate is achieved over 80 km single mode fiber (SMF).

American Brachytherapy Society consensus report for accelerated partial breast irradiation using interstitial multicatheter brachytherapy.

PubMed

Hepel, Jaroslaw T; Arthur, Douglas; Shaitelman, Simona; Polgár, Csaba; Todor, Dorin; Zoberi, Imran; Kamrava, Mitchell; Major, Tibor; Yashar, Catheryn; Wazer, David E

To develop a consensus report for the quality practice of accelerated partial breast irradiation (APBI) using interstitial multicatheter brachytherapy (IMB). The American Brachytherapy Society Board appointed an expert panel with clinical and research experience with breast brachytherapy to provide guidance for the current practice of IMB. This report is based on a comprehensive literature review with emphasis on randomized data and expertise of the panel. Randomized trials have demonstrated equivalent efficacy of APBI using IMB compared with whole breast irradiation for select patients with early-stage breast cancer. Several techniques for placement of interstitial catheters are described, and importance of three-dimensional planning with appropriate optimization is reviewed. Optimal target definition is outlined. Commonly used dosing schemas include 50 Gy delivered in pulses of 0.6-0.8 Gy/h using pulsed-dose-rate technique and 34 Gy in 10 fractions, 32 Gy in eight fractions, or 30 Gy in seven fractions using high-dose-rate technique. Potential toxicities and strategies for toxicity avoidance are described in detail. Dosimetric constraints include limiting whole breast volume that receives ≥50% of prescription dose to <60%, skin dose to ≤100% of prescription dose (≤60-70% preferred), chest wall dose to ≤125% of prescription dose, Dose Homogeneity Index to >0.75 (>0.85 preferred), V 150  < 45 cc, and V 200  < 14 cc. Using an optimal implant technique coupled with optimal planning and appropriate dose constraints, a low rate of toxicity and a good-to-excellent cosmetic outcome of ≥90% is expected. IMB is an effective technique to deliver APBI for appropriately selected women with early-stage breast cancer. This consensus report has been created to assist clinicians in the appropriate practice of APBI using IMB. Copyright © 2017 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

Synthesis of [{sup 125}I]iodoDPA-713: A new probe for imaging inflammation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Haofan; Pullambhatla, Mrudula; Guilarte, Tomas R.

2009-11-06

[{sup 125}I]IodoDPA-713 [{sup 125}I]1, which targets the translocator protein (TSPO, 18 kDa), was synthesized in seven steps from methyl-4-methoxybenzoate as a tool for quantification of inflammation in preclinical models. Preliminary in vitro autoradiography and in vivo small animal imaging were performed using [{sup 125}I]1 in a neurotoxicant-treated rat and in a murine model of lung inflammation, respectively. The radiochemical yield of [{sup 125}I]1 was 44 {+-} 6% with a specific radioactivity of 51.8 GBq/{mu}mol (1400 mCi/{mu}mol) and >99% radiochemical purity. Preliminary studies showed that [{sup 125}I]1 demonstrated increased specific binding to TSPO in a neurotoxicant-treated rat and increased radiopharmaceutical uptakemore » in the lungs of an experimental inflammation model of lung inflammation. Compound [{sup 125}I]1 is a new, convenient probe for preclinical studies of TSPO activity.« less

Radioimmunoassay of salivary cyclosporine with use of /sup 125/I-labeled cyclosporine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Coates, J.E.; Lam, S.F.; McGaw, W.T.

1988-08-01

We prepared /sup 125/I-labeled cyclosporine (/sup 125/I-CS) by modifying the procedure of Mahoney and Orf and characterized it with regards to maximal immunoreactivity (greater than 90%), trichloroacetic acid precipitability (greater than 90%), and stability (90% immunoreactive after five half-lives of /sup 125/I). For a particular preparation of /sup 125/I-CS, we estimated its immunoreaction concentration (50 pmol/L) and the equilibrium constant for its reaction with Sandoz polyclonal antiserum (K = 3.9 X 10(9) L/mol). By substituting /sup 125/I-CS as tracer in the Sandoz radioimmunoassay and by modifying other aspects of the assay, we developed a procedure that is sufficiently sensitive (0.34more » micrograms/L) to allow measurement of trough (lowest inter-dose) cyclosporine concentrations in parotid saliva. Of 38 kidney-transplant patients, 35 had measurable concentrations in saliva (mean 8.3, SD 5.2 micrograms/L), and these correlated moderately with paired serum concentrations (r = 0.68, P less than 0.001). We believe that measurement of salivary cyclosporine may offer a simple way of estimating the free fraction of the drug in serum or plasma.« less

Dependence with air density of the response of the PTW SourceCheck ionization chamber for low energy brachytherapy sources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tornero-López, Ana M.; Guirado, Damián; Ruiz-Arrebola, Samuel

2013-12-15

Purpose: Air-communicating well ionization chambers are commonly used to assess air kerma strength of sources used in brachytherapy. The signal produced is supposed to be proportional to the air density within the chamber and, therefore, a density-independent air kerma strength is obtained when the measurement is corrected to standard atmospheric conditions using the usual temperature and pressure correction factor. Nevertheless, when assessing low energy sources, the ionization chambers may not fulfill that condition and a residual density dependence still remains after correction. In this work, the authors examined the behavior of the PTW 34051 SourceCheck ionization chamber when measuring themore » air kerma strength of {sup 125}I seeds.Methods: Four different SourceCheck chambers were analyzed. With each one of them, two series of measurements of the air kerma strength for {sup 125}I selectSeed{sup TM} brachytherapy sources were performed inside a pressure chamber and varying the pressure in a range from 747 to 1040 hPa (560 to 780 mm Hg). The temperature and relative humidity were kept basically constant. An analogous experiment was performed by taking measurements at different altitudes above sea level.Results: Contrary to other well-known ionization chambers, like the HDR1000 PLUS, in which the temperature-pressure correction factor overcorrects the measurements, in the SourceCheck ionization chamber they are undercorrected. At a typical atmospheric situation of 933 hPa (700 mm Hg) and 20 °C, this undercorrection turns out to be 1.5%. Corrected measurements show a residual linear dependence on the density and, as a consequence, an additional density dependent correction must be applied. The slope of this residual linear density dependence is different for each SourceCheck chamber investigated. The results obtained by taking measurements at different altitudes are compatible with those obtained with the pressure chamber.Conclusions: Variations of the

Long-Term Outcomes of Alternative Brachytherapy Techniques for Early Prostate Cancer

DTIC Science & Technology

2007-01-01

Oncol 2003;21:3979-86. 15. Whitmore WF, Jr., Hilaris B, Grabstald H. Retropubic implantation to iodine 125 in the treatment of prostatic cancer. J...brachytherapy and external beam irradiation for clinically localized, high-risk prostatic carcinoma. Int J Radiat Oncol Biol Phys 1996;35:875-9. 29. Stock RG

Radioiodination of scorpion and snake toxins. [/sup 125/I, /sup 127/I

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rochat, H.; Tessier, M.; Miranda, F.

1977-10-01

Several scorpion and snake toxins were radioiodinated using the lactoperoxydase method of (/sup 125/I)iodide oxidation. Two techniques of labeling were set up: Using carrier-free Na/sup 125/I and 5 ..mu..g of toxin, about one iodine atom was incorporated per mole of protein without loss of toxicity. Specific radioactivities about 2,000 Ci/mmol (280 ..mu..Ci/..mu..g) were obtained. The modified toxin, purified by immunoprecipitation with an antiserum prepared against the native toxin, was obtained in a short time (4 hr), with a good yield (50 to 80%), and in a small volume (1 ml). Using Na/sup 127/I traced with Na /sup 125/I and largermore » amounts (200 ..mu..g) of toxin, more than one iodine atom was incorporated per mole of protein without loss of activity. Lower specific radioactivities (1 to 1.5 Ci/mmol) were obtained. The iodinated toxins were purified by gel filtration of the radioiodination mixtures on a column made of two layers of Sephadex (G-15 and G-50). The modified proteins were extensively analyzed by paper electrophoresis and polyacrylamide gel electrophoresis. Their content of monoiodotyrosine and diiodotyrosine was estimated and, in the case of toxin I of Androctonus australis Hector, it was possible to follow the iodination rate of its three tyrosine residues by automatic Edman degradation. The mode of purification of the iodinated scorpion toxins affects their behavior on molecular sieving on Sephadex G-50 and on electrophoresis on polyacrylamide gel. The results are discussed.« less

Evaluation of two (125)I-radiolabeled acridine derivatives for Auger-electron radionuclide therapy of melanoma.

PubMed

Gardette, Maryline; Viallard, Claire; Paillas, Salomé; Guerquin-Kern, Jean-Luc; Papon, Janine; Moins, Nicole; Labarre, Pierre; Desbois, Nicolas; Wong-Wah-Chung, Pascal; Palle, Sabine; Wu, Ting-Di; Pouget, Jean-Pierre; Miot-Noirault, Elisabeth; Chezal, Jean-Michel; Degoul, Francoise

2014-08-01

We previously selected two melanin-targeting radioligands [(125)I]ICF01035 and [(125)I]ICF01040 for melanoma-targeted (125)I radionuclide therapy according to their pharmacological profile in mice bearing B16F0 tumors. Here we demonstrate in vitro that these compounds present different radiotoxicities in relation to melanin and acidic vesicle contents in B16F0, B16F0 PTU and A375 cell lines. ICF01035 is effectively observed in nuclei of achromic (A375) melanoma or in melanosomes of melanized melanoma (B16F0), while ICF01040 stays in cytoplasmic vesicles in both cells. [(125)I]ICF01035 induced a similar survival fraction (A50) in all cell lines and led to a significant decrease in S-phase cells in amelanotic cell lines. [(125)I]ICF01040 induced a higher A50 in B16 cell lines compared to [(125)I]ICF01035 ones. [(125)I]ICF01040 induced a G2/M blockade in both A375 and B16F0 PTU, associated with its presence in cytoplasmic acidic vesicles. These results suggest that the radiotoxicity of [(125)I]ICF01035 and [(125)I]ICF01040 are not exclusively reliant on DNA alterations compatible with γ rays but likely result from local dose deposition (Auger electrons) leading to toxic compound leaks from acidic vesicles. In vivo, [(125)I]ICF01035 significantly reduced the number of B16F0 lung colonies, enabling a significant increase in survival of the treated mice. Targeting melanosomes or acidic vesicles is thus an option for future melanoma therapy.

Intracellular processing of epidermal growth factor. I. Acidification of 125I-epidermal growth factor in intracellular organelles.

PubMed

Matrisian, L M; Planck, S R; Magun, B E

1984-03-10

We previously reported that 125I-labeled epidermal growth factor is processed intracellularly to acidic macromolecules in Rat-1 fibroblasts. The present study defines the precursor-product relationship and localization of the processing steps to subcellular organelles by the use of a single isoelectric species of 125I-epidermal growth factor and Percoll gradient fractionation. The native pI 4.55 125I-epidermal growth factor was rapidly processed to a pI 4.2 species on or near the cell surface and in organelles corresponding to clathrin-coated vesicles, Golgi, and endoplasmic reticulum. This species was then processed to a pI 4.35 species in similar organelles. The pI 4.2 and 4.35 species were converted to a pI 4.0 species in dense, lysosome-like organelles. This species was ultimately degraded and exocytosed from the cell as low molecular weight products.

High dose rate brachytherapy for oral cancer.

PubMed

Yamazaki, Hideya; Yoshida, Ken; Yoshioka, Yasuo; Shimizutani, Kimishige; Furukawa, Souhei; Koizumi, Masahiko; Ogawa, Kazuhiko

2013-01-01

Brachytherapy results in better dose distribution compared with other treatments because of steep dose reduction in the surrounding normal tissues. Excellent local control rates and acceptable side effects have been demonstrated with brachytherapy as a sole treatment modality, a postoperative method, and a method of reirradiation. Low-dose-rate (LDR) brachytherapy has been employed worldwide for its superior outcome. With the advent of technology, high-dose-rate (HDR) brachytherapy has enabled health care providers to avoid radiation exposure. This therapy has been used for treating many types of cancer such as gynecological cancer, breast cancer, and prostate cancer. However, LDR and pulsed-dose-rate interstitial brachytherapies have been mainstays for head and neck cancer. HDR brachytherapy has not become widely used in the radiotherapy community for treating head and neck cancer because of lack of experience and biological concerns. On the other hand, because HDR brachytherapy is less time-consuming, treatment can occasionally be administered on an outpatient basis. For the convenience and safety of patients and medical staff, HDR brachytherapy should be explored. To enhance the role of this therapy in treatment of head and neck lesions, we have reviewed its outcomes with oral cancer, including Phase I/II to Phase III studies, evaluating this technique in terms of safety and efficacy. In particular, our studies have shown that superficial tumors can be treated using a non-invasive mold technique on an outpatient basis without adverse reactions. The next generation of image-guided brachytherapy using HDR has been discussed. In conclusion, although concrete evidence is yet to be produced with a sophisticated study in a reproducible manner, HDR brachytherapy remains an important option for treatment of oral cancer.

Effect of aging and long-term erectile function after iodine-125 prostate brachytherapy.

PubMed

Keyes, Mira; Pickles, Tom; Crook, Juanita; McKenzie, Michael; Cheung, Arthur; Spadinger, Ingrid; LaPointe, Vincent; Bachand, W Francois; Morris, James

2015-01-01

To evaluate long-term erectile function (EF) in men treated with iodine-125 prostate brachytherapy (PB) and to determine factors predictive for erectile dysfunction (ED), including natural decline because of aging. Two thousand nine hundred twenty-nine patients (implanted July 1989-June 2012) with baseline EF and greater than 10-month followup (FU) are included. About 78.9% had full and 7.9% had partial EF at baseline. EF was assessed on a physician-reported three-point scale. Poisson regression with generalized estimating equations was used to assess predictors of ED and Kaplan-Meier curves time to ED. The effect of aging was calculated from the declining rate of baseline EF seen in sequential 5-year age cohorts and from the Massachusetts Male Aging Study. The median age was 66 years and median FU 3.5 years (maximum 14 years). About 1142 patients had more than 5 years of FU, and 43% had received 6 months of androgen deprivation therapy (ADT). Significant drop in EF was seen at 6 weeks after PB, with gradual decline thereafter. EF preservation at 5 years for age younger than 55, 56-59, 60-64, 65-69, and 70 year and older was 82%, 73%, 58%, 39%, and 23%, respectively. Comparisons of the 5-year age-related and treatment-related EF decline show that 50% of the long-term EF decline is related to aging. On univariate and multivariate analyses, age at implant, length of FU, hypertension, diabetes, and use of ADT (all p < 0.01) were significant predictors of ED. More than 80% of young men have EF preserved 5 years after PB. Age, ADT, history of hypertension, and the natural decline in EF have negative impact on long-term EF after PB. Crown Copyright © 2015. Published by Elsevier Inc. All rights reserved.

Practical considerations for maximizing heat production in a novel thermobrachytherapy seed prototype

PubMed Central

Gautam, Bhoj; Warrell, Gregory; Shvydka, Diana; Subramanian, Manny; Ishmael Parsai, E.

2014-01-01

Purpose: A combination of hyperthermia and radiation in the treatment of cancer has been proven to provide better tumor control than radiation administered as a monomodality, without an increase in complications or serious toxicities. Moreover, concurrent administration of hyperthermia and radiation displays synergistic enhancement, resulting in greater tumor cell killing than hyperthermia and radiation delivered separately. The authors have designed a new thermobrachytherapy (TB) seed, which serves as a source of both radiation and heat for concurrent brachytherapy and hyperthermia treatments when implanted in solid tumors. This innovative seed, similar in size and geometry to conventional seeds, will have self-regulating thermal properties. Methods: The new seed's geometry is based on the standard BEST Model 2301 125I seed, resulting in very similar dosimetric properties. The TB seed generates heat when placed in an oscillating magnetic field via induction heating of a ferromagnetic Ni–Cu alloy core that replaces the tungsten radiographic marker of the standard Model 2301. The alloy composition is selected to undergo a Curie transition near 50 °C, drastically decreasing power production at higher temperatures and providing for temperature self-regulation. Here, the authors present experimental studies of the magnetic properties of Ni–Cu alloy material, the visibility of TB seeds in radiographic imaging, and the ability of seed prototypes to uniformly heat tissue to a desirable temperature. Moreover, analyses are presented of magnetic shielding and thermal expansion of the TB seed, as well as matching of radiation dose to temperature distributions for a short interseed distance in a given treatment volume. Results: Annealing the Ni–Cu alloy has a significant effect on its magnetization properties, increasing the sharpness of the Curie transition. The TB seed preserves the radiographic properties of the BEST 2301 seed in both plain x rays and CT images

Practical considerations for maximizing heat production in a novel thermobrachytherapy seed prototype

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gautam, Bhoj; Warrell, Gregory; Shvydka, Diana

2014-02-15

Purpose: A combination of hyperthermia and radiation in the treatment of cancer has been proven to provide better tumor control than radiation administered as a monomodality, without an increase in complications or serious toxicities. Moreover, concurrent administration of hyperthermia and radiation displays synergistic enhancement, resulting in greater tumor cell killing than hyperthermia and radiation delivered separately. The authors have designed a new thermobrachytherapy (TB) seed, which serves as a source of both radiation and heat for concurrent brachytherapy and hyperthermia treatments when implanted in solid tumors. This innovative seed, similar in size and geometry to conventional seeds, will have self-regulatingmore » thermal properties. Methods: The new seed's geometry is based on the standard BEST Model 2301{sup 125}I seed, resulting in very similar dosimetric properties. The TB seed generates heat when placed in an oscillating magnetic field via induction heating of a ferromagnetic Ni–Cu alloy core that replaces the tungsten radiographic marker of the standard Model 2301. The alloy composition is selected to undergo a Curie transition near 50 °C, drastically decreasing power production at higher temperatures and providing for temperature self-regulation. Here, the authors present experimental studies of the magnetic properties of Ni–Cu alloy material, the visibility of TB seeds in radiographic imaging, and the ability of seed prototypes to uniformly heat tissue to a desirable temperature. Moreover, analyses are presented of magnetic shielding and thermal expansion of the TB seed, as well as matching of radiation dose to temperature distributions for a short interseed distance in a given treatment volume. Results: Annealing the Ni–Cu alloy has a significant effect on its magnetization properties, increasing the sharpness of the Curie transition. The TB seed preserves the radiographic properties of the BEST 2301 seed in both plain x rays and

Practical considerations for maximizing heat production in a novel thermobrachytherapy seed prototype

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gautam, Bhoj; Warrell, Gregory; Shvydka, Diana

Purpose: A combination of hyperthermia and radiation in the treatment of cancer has been proven to provide better tumor control than radiation administered as a monomodality, without an increase in complications or serious toxicities. Moreover, concurrent administration of hyperthermia and radiation displays synergistic enhancement, resulting in greater tumor cell killing than hyperthermia and radiation delivered separately. The authors have designed a new thermobrachytherapy (TB) seed, which serves as a source of both radiation and heat for concurrent brachytherapy and hyperthermia treatments when implanted in solid tumors. This innovative seed, similar in size and geometry to conventional seeds, will have self-regulatingmore » thermal properties. Methods: The new seed's geometry is based on the standard BEST Model 2301{sup 125}I seed, resulting in very similar dosimetric properties. The TB seed generates heat when placed in an oscillating magnetic field via induction heating of a ferromagnetic Ni–Cu alloy core that replaces the tungsten radiographic marker of the standard Model 2301. The alloy composition is selected to undergo a Curie transition near 50 °C, drastically decreasing power production at higher temperatures and providing for temperature self-regulation. Here, the authors present experimental studies of the magnetic properties of Ni–Cu alloy material, the visibility of TB seeds in radiographic imaging, and the ability of seed prototypes to uniformly heat tissue to a desirable temperature. Moreover, analyses are presented of magnetic shielding and thermal expansion of the TB seed, as well as matching of radiation dose to temperature distributions for a short interseed distance in a given treatment volume. Results: Annealing the Ni–Cu alloy has a significant effect on its magnetization properties, increasing the sharpness of the Curie transition. The TB seed preserves the radiographic properties of the BEST 2301 seed in both plain x rays and

Keeping an eye on the ring: COMS plaque loading optimization for improved dose conformity and homogeneity.

PubMed

Gagne, Nolan L; Cutright, Daniel R; Rivard, Mark J

2012-09-01

To improve tumor dose conformity and homogeneity for COMS plaque brachytherapy by investigating the dosimetric effects of varying component source ring radionuclides and source strengths. The MCNP5 Monte Carlo (MC) radiation transport code was used to simulate plaque heterogeneity-corrected dose distributions for individually-activated source rings of 14, 16 and 18 mm diameter COMS plaques, populated with (103)Pd, (125)I and (131)Cs sources. Ellipsoidal tumors were contoured for each plaque size and MATLAB programming was developed to generate tumor dose distributions for all possible ring weighting and radionuclide permutations for a given plaque size and source strength resolution, assuming a 75 Gy apical prescription dose. These dose distributions were analyzed for conformity and homogeneity and compared to reference dose distributions from uniformly-loaded (125)I plaques. The most conformal and homogeneous dose distributions were reproduced within a reference eye environment to assess organ-at-risk (OAR) doses in the Pinnacle(3) treatment planning system (TPS). The gamma-index analysis method was used to quantitatively compare MC and TPS-generated dose distributions. Concentrating > 97% of the total source strength in a single or pair of central (103)Pd seeds produced the most conformal dose distributions, with tumor basal doses a factor of 2-3 higher and OAR doses a factor of 2-3 lower than those of corresponding uniformly-loaded (125)I plaques. Concentrating 82-86% of the total source strength in peripherally-loaded (131)Cs seeds produced the most homogeneous dose distributions, with tumor basal doses 17-25% lower and OAR doses typically 20% higher than those of corresponding uniformly-loaded (125)I plaques. Gamma-index analysis found > 99% agreement between MC and TPS dose distributions. A method was developed to select intra-plaque ring radionuclide compositions and source strengths to deliver more conformal and homogeneous tumor dose distributions than

Brachytherapy of prostate cancer after colectomy for colorectal cancer: pilot experience.

PubMed

Koutrouvelis, Panos G; Theodorescu, Dan; Katz, Stuart; Lailas, Niko; Hendricks, Fred

2005-01-01

We present a method of brachytherapy for prostate cancer using a 3-dimensional stereotactic system and computerized tomography guidance in patients without a rectum due to previous treatment for colorectal cancer. From June 1994 to November 2003 a cohort of 800 patients were treated with brachytherapy for prostate cancer. Four patients had previously been treated for colorectal cancer with 4,500 cGy external beam radiation therapy, abdominoperineal resection and chemotherapy, while 1 underwent abdominoperineal resection alone for ulcerative colitis. Because of previous radiation therapy, these patients were not candidates for salvage external beam radiation therapy or radical prostatectomy and they had no rectum for transrectal ultrasound guided transperineal brachytherapy or cryotherapy. A previously described, 3-dimensional stereotactic system was used for brachytherapy in these patients. The prescribed radiation dose was 120 to 144 Gy with iodine seeds in rapid strand format. Patient followup included clinical examination and serum prostate specific antigen measurement. Average followup was 18.6 months. Four patients had excellent biochemical control, while 1 had biochemical failure. Patients did not experience any gastrointestinal morbidity. One patient had a stricture of the distal ureter, requiring a stent. Three-dimensional computerized tomography guided brachytherapy for prostate cancer in patients with a history of colorectal cancer who have no rectum is a feasible method of treatment.

SU-F-T-09: In Phantom Full-Implant Validation of Plastic Scintillation Detectors for in Vivo Dosimetry During Low Dose Rate Brachytherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Therriault-Proulx, F; Bruno, T; Beddar, S

Purpose: To validate in a water phantom the use of plastic scintillation detectors to measure dose to the urethra and the rectal wall during a clinically realistic low dose rate (LDR) brachytherapy implant. Methods: A template was designed to replicate a clinically realistic LDR brachytherapy prostate implant inside a water phantom. Twenty-two catheters were inserted, including one mimicking the urethra and another the rectal wall. The needles inserted in the remaining 20 catheters were composed of thin-walled nylon tubes in which I-125 radioactive seeds (Air Kerma Strengths of (0.328±0.020)U) were abutted together with plastic spacers to replicate a typical loading.more » A plastic scintillation detector (PSD) with a 5-mm long × 1-mm diameter sensitive element was first placed inside the urethra and 1-second measurements were performed for 60s after each needle implant. Measurements were also performed at multiple positions along the urethra once all the needles were inserted. The procedure was then repeated with the PSD placed at the rectal wall. Results: Individual dose-rates ranging from 0.07µGy/s to 1.5µGy/s were measured after each needle implant. The average absolute relative differences were (6.2±3.6)% and (6.9±6.5)% to the values calculated with the TG-43 formalism, for the urethra and rectal wall respectively. These results are within expectations from the error uncertainty budget once accounting for uncertainties in seeds’ strength and positioning. Interestingly, the PSD allowed for unplanned error detection as the study was performed. Finally, the measured dose after the full implant at different positions along the mimicked organs at risk were in agreement with TG-43 values for all of the positions tested. Conclusion: Plastic scintillation detectors could be used as in vivo detectors for LDR brachytherapy as they would provide accurate dose information after each needle implant as well as along the organs at risk at the end of the implant.« less

Placement of empty catheters for an HDR-emulating LDR prostate brachytherapy technique: comparison to standard intraoperative planning.

PubMed

Niedermayr, Thomas R; Nguyen, Paul L; Murciano-Goroff, Yonina R; Kovtun, Konstantin A; Neubauer Sugar, Emily; Cail, Daniel W; O'Farrell, Desmond A; Hansen, Jorgen L; Cormack, Robert A; Buzurovic, Ivan; Wolfsberger, Luciant T; O'Leary, Michael P; Steele, Graeme S; Devlin, Philip M; Orio, Peter F

2014-01-01

We sought to determine whether placing empty catheters within the prostate and then inverse planning iodine-125 seed locations within those catheters (High Dose Rate-Emulating Low Dose Rate Prostate Brachytherapy [HELP] technique) would improve concordance between planned and achieved dosimetry compared with a standard intraoperative technique. We examined 30 consecutive low dose rate prostate cases performed by standard intraoperative technique of planning followed by needle placement/seed deposition and compared them to 30 consecutive low dose rate prostate cases performed by the HELP technique. The primary endpoint was concordance between planned percentage of the clinical target volume that receives at least 100% of the prescribed dose/dose that covers 90% of the volume of the clinical target volume (V100/D90) and the actual V100/D90 achieved at Postoperative Day 1. The HELP technique had superior concordance between the planned target dosimetry and what was actually achieved at Day 1 and Day 30. Specifically, target D90 at Day 1 was on average 33.7 Gy less than planned for the standard intraoperative technique but was only 10.5 Gy less than planned for the HELP technique (p < 0.001). Day 30 values were 16.6 Gy less vs. 2.2 Gy more than planned, respectively (p = 0.028). Day 1 target V100 was 6.3% less than planned with standard vs. 2.8% less for HELP (p < 0.001). There was no significant difference between the urethral and rectal concordance (all p > 0.05). Placing empty needles first and optimizing the plan to the known positions of the needles resulted in improved concordance between the planned and the achieved dosimetry to the target, possibly because of elimination of errors in needle placement. Copyright © 2014 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

High dose rate brachytherapy for oral cancer

PubMed Central

YamazakI, Hideya; Yoshida, Ken; Yoshioka, Yasuo; Shimizutani, Kimishige; Furukawa, Souhei; Koizumi, Masahiko; Ogawa, Kazuhiko

2013-01-01

Brachytherapy results in better dose distribution compared with other treatments because of steep dose reduction in the surrounding normal tissues. Excellent local control rates and acceptable side effects have been demonstrated with brachytherapy as a sole treatment modality, a postoperative method, and a method of reirradiation. Low-dose-rate (LDR) brachytherapy has been employed worldwide for its superior outcome. With the advent of technology, high-dose-rate (HDR) brachytherapy has enabled health care providers to avoid radiation exposure. This therapy has been used for treating many types of cancer such as gynecological cancer, breast cancer, and prostate cancer. However, LDR and pulsed-dose-rate interstitial brachytherapies have been mainstays for head and neck cancer. HDR brachytherapy has not become widely used in the radiotherapy community for treating head and neck cancer because of lack of experience and biological concerns. On the other hand, because HDR brachytherapy is less time-consuming, treatment can occasionally be administered on an outpatient basis. For the convenience and safety of patients and medical staff, HDR brachytherapy should be explored. To enhance the role of this therapy in treatment of head and neck lesions, we have reviewed its outcomes with oral cancer, including Phase I/II to Phase III studies, evaluating this technique in terms of safety and efficacy. In particular, our studies have shown that superficial tumors can be treated using a non-invasive mold technique on an outpatient basis without adverse reactions. The next generation of image-guided brachytherapy using HDR has been discussed. In conclusion, although concrete evidence is yet to be produced with a sophisticated study in a reproducible manner, HDR brachytherapy remains an important option for treatment of oral cancer. PMID:23179377

Enhanced Ultrasound Visualization of Bracytherapy Seeds by a Novel Magnetically Induced Motion Imaging Method

DTIC Science & Technology

2008-04-01

We report our progress in developing Magnetically Induced Motion Imaging (MIMI) for unambiguous identification and localization brachytherapy seeds ...in ultrasound images. Coupled finite element and ultrasound imaging simulations have been performed to demonstrate that seeds are detectable with MIMI

Episcleral eye plaque dosimetry comparison for the Eye Physics EP917 using Plaque Simulator and Monte Carlo simulation

PubMed Central

Amoush, Ahmad; Wilkinson, Douglas A.

2015-01-01

This work is a comparative study of the dosimetry calculated by Plaque Simulator, a treatment planning system for eye plaque brachytherapy, to the dosimetry calculated using Monte Carlo simulation for an Eye Physics model EP917 eye plaque. Monte Carlo (MC) simulation using MCNPX 2.7 was used to calculate the central axis dose in water for an EP917 eye plaque fully loaded with 17 IsoAid Advantage  125I seeds. In addition, the dosimetry parameters Λ, gL(r), and F(r,θ) were calculated for the IsoAid Advantage model IAI‐125  125I seed and benchmarked against published data. Bebig Plaque Simulator (PS) v5.74 was used to calculate the central axis dose based on the AAPM Updated Task Group 43 (TG‐43U1) dose formalism. The calculated central axis dose from MC and PS was then compared. When the MC dosimetry parameters for the IsoAid Advantage  125I seed were compared with the consensus values, Λ agreed with the consensus value to within 2.3%. However, much larger differences were found between MC calculated gL(r) and F(r,θ) and the consensus values. The differences between MC‐calculated dosimetry parameters are much smaller when compared with recently published data. The differences between the calculated central axis absolute dose from MC and PS ranged from 5% to 10% for distances between 1 and 12 mm from the outer scleral surface. When the dosimetry parameters for the  125I seed from this study were used in PS, the calculated absolute central axis dose differences were reduced by 2.3% from depths of 4 to 12 mm from the outer scleral surface. We conclude that PS adequately models the central dose profile of this plaque using its defaults for the IsoAid model IAI‐125 at distances of 1 to 7 mm from the outer scleral surface. However, improved dose accuracy can be obtained by using updated dosimetry parameters for the IsoAid model IAI‐125  125I seed. PACS number: 87.55.K‐ PMID:26699577

Radioimmunoassay for etorphine in horses with a /sup 125/I analog of etorphine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tai, C.L.; Wang, C.; Weckman, T.J.

1988-05-01

To improve the sensitivity and specificity of screening for etorphine in horses, an /sup 125/I-labeled etorphine analog was synthesized and an antibody to etorphine was raised in rabbits. A radioimmunoassay (RIA) for etorphine was developed, using these reagents. Bound and free /sup 125/I-labeled etorphine was separated by a double-antibody method that reduced interference from materials associated with equine urine. The /sup 125/I-labeled etorphine binding was rarely greater than 250 pg of background etorphine equivalents/ml in raw urine and was 100 pg/ml in hydrolyzed urine. The /sup 125/I-RIA was capable of detecting etorphine equivalents in urine above these background values. Etorphinemore » equivalents were detected in equine urine samples for about 7 days after 4 mares were dosed with 0.22 microgram of etorphine/kg of body weight, IV. The stability of etorphine in urine from these mares was evaluated. Urine from these dosed mares was held in constant -20 C storage, and aliquots were repeatedly frozen and thawed. When analyzed for etorphine equivalents using an /sup 125/I-RIA, etorphine and its metabolites in urine samples were stable for less than or equal to 38 days if continuously frozen and also were resistant to repeated freezing and thawing.« less

Magnetic resonance spectroscopy-guided transperineal prostate biopsy and brachytherapy for recurrent prostate cancer.

PubMed

Barnes, Agnieszka Szot; Haker, Steven J; Mulkern, Robert V; So, Minna; D'Amico, Anthony V; Tempany, Clare M

2005-12-01

Brachytherapy targeted to the peripheral zone with magnetic resonance imaging (MRI) guidance is a prostate cancer treatment option with potentially fewer complications than other treatments. Follow-up MRI when failure is suspected is, however, difficult because of radiation-induced changes. Furthermore, MR spectroscopy (MRS) is compromised by susceptibility artifacts from radioactive seeds in the peripheral zone. We report a case in which combined MRI/MRS was useful for the detection of prostate cancer in the transitional zone in patients previously treated with MR-guided brachytherapy. We propose that MRI/MRS can help detect recurrent prostate cancer, guide prostate biopsy, and help manage salvage treatment decisions.

Potential risk of acute toxicity induced by AgI cloud seeding on soil and freshwater biota.

PubMed

Fajardo, C; Costa, G; Ortiz, L T; Nande, M; Rodríguez-Membibre, M L; Martín, M; Sánchez-Fortún, S

2016-11-01

Silver iodide is one of the most common nucleating materials used in cloud seeding. Previous cloud seeding studies have concluded that AgI is not practically bioavailable in the environment but instead remains in soils and sediments such that the free Ag amounts are likely too low to induce a toxicological effect. However, none of these studies has considered the continued use of this practice on the same geographical areas and thus the potential cumulative effect of environmental AgI. The aim of this study is to assess the risk of acute toxicity caused by AgI exposure under laboratory conditions at the concentration expected in the environment after repeated treatments on selected soil and aquatic biota. To achieve the aims, the viability of soil bacteria Bacillus cereus and Pseudomonas stutzeri and the survival of the nematode Caenorhabditis elegans exposed to different silver iodide concentrations have been evaluated. Freshwater green algae Dictyosphaerium chlorelloides and cyanobacteria Microcystis aeruginosa were exposed to silver iodide in culture medium, and their cell viability and photosynthetic activity were evaluated. Additionally, BOD5 exertion and the Microtox® toxicity test were included in the battery of toxicological assays. Both tests exhibited a moderate AgI adverse effect at the highest concentration (12.5µM) tested. However, AgI concentrations below 2.5µM increased BOD5. Although no impact on the growth and survival endpoints in the soil worm C. elegans was recorded after AgI exposures, a moderate decrease in cell viability was found for both of the assessed soil bacterial strains at the studied concentrations. Comparison between the studied species showed that the cyanobacteria were more sensitive than green algae. Exposure to AgI at 0.43μM, the reference value used in monitoring environmental impact, induced a significant decrease in photosynthetic activity that is primarily associated with the respiration (80% inhibition) and, to a lesser

Dose heterogeneity correction for low-energy brachytherapy sources using dual-energy CT images

NASA Astrophysics Data System (ADS)

Mashouf, S.; Lechtman, E.; Lai, P.; Keller, B. M.; Karotki, A.; Beachey, D. J.; Pignol, J. P.

2014-09-01

Permanent seed implant brachytherapy is currently used for adjuvant radiotherapy of early stage prostate and breast cancer patients. The current standard for calculation of dose around brachytherapy sources is based on the AAPM TG-43 formalism, which generates the dose in a homogeneous water medium. Recently, AAPM TG-186 emphasized the importance of accounting for tissue heterogeneities. We have previously reported on a methodology where the absorbed dose in tissue can be obtained by multiplying the dose, calculated by the TG-43 formalism, by an inhomogeneity correction factor (ICF). In this work we make use of dual energy CT (DECT) images to extract ICF parameters. The advantage of DECT over conventional CT is that it eliminates the need for tissue segmentation as well as assignment of population based atomic compositions. DECT images of a heterogeneous phantom were acquired and the dose was calculated using both TG-43 and TG-43 × \\text{ICF} formalisms. The results were compared to experimental measurements using Gafchromic films in the mid-plane of the phantom. For a seed implant configuration of 8 seeds spaced 1.5 cm apart in a cubic structure, the gamma passing score for 2%/2 mm criteria improved from 40.8% to 90.5% when ICF was applied to TG-43 dose distributions.

Attenuation of iodine 125 radiation with vitreous substitutes in the treatment of uveal melanoma.

PubMed

Oliver, Scott C N; Leu, Min Y; DeMarco, John J; Chow, Philip E; Lee, Steve P; McCannel, Tara A

2010-07-01

To demonstrate attenuation of radiation from iodine 125 ((125)I) to intraocular structures using liquid vitreous substitutes. Four candidate vitreous substitutes were tested for attenuation using empirical measurement and theoretical calculation. In vitro and ex vivo cadaveric dosimetry measurements were obtained with lithium fluoride thermoluminescent dosimeters to demonstrate the attenuation effect of vitreous substitution during (125)I simulated plaque brachytherapy. Theoretical dosimetry calculations were based on Monte Carlo simulation. In a cylindrical phantom at a 17-mm depth, liquid vitreous substitutes as compared with saline showed significant reduction of radiation penetration (48% for 1000-centistoke [cSt] silicone oil [polydimethyl-n-siloxane], 47% for 5000-cSt silicone oil [polydimethyl-n-siloxane], 40% for heavy oil [perfluorohexyloctane/polydimethyl-n-siloxane], and 35% for perfluorocarbon liquid [perfluoro-n-octane]). Human cadaveric ex vivo measurements demonstrated a 1000-cSt silicone oil to saline dose ratio of 35%, 52%, 55%, and 48% at arc lengths of 7.6, 10.6, 22.3, and 28.6 mm from the plaque edge, respectively, along the surface of the globe. Monte Carlo simulation of a human globe projected attenuation as high as 57% using 1000-cSt silicone oil. Intraocular vitreous substitutes including silicone oil, heavy oil, and perfluorocarbon liquid attenuate the radiation dose from (125)I. Cadaveric ex vivo measurements and Monte Carlo simulation both demonstrate radiation attenuation using 1000-cSt silicone oil at distances corresponding to vital ocular structures. Clinical Relevance Attenuation of radiation with silicone oil endotamponade in the treatment of uveal melanoma may significantly reduce radiation-induced injury to vital ocular structures.

12 CFR 550.125 - How do I file the notice under § 550.70(c)?

Code of Federal Regulations, 2010 CFR

2010-01-01

... 12 Banks and Banking 5 2010-01-01 2010-01-01 false How do I file the notice under § 550.70(c)? 550.125 Section 550.125 Banks and Banking OFFICE OF THRIFT SUPERVISION, DEPARTMENT OF THE TREASURY FIDUCIARY POWERS OF SAVINGS ASSOCIATIONS Obtaining Fiduciary Powers § 550.125 How do I file the notice under...

12 CFR 550.125 - How do I file the notice under § 550.70(c)?

Code of Federal Regulations, 2011 CFR

2011-01-01

... 12 Banks and Banking 5 2011-01-01 2011-01-01 false How do I file the notice under § 550.70(c)? 550.125 Section 550.125 Banks and Banking OFFICE OF THRIFT SUPERVISION, DEPARTMENT OF THE TREASURY FIDUCIARY POWERS OF SAVINGS ASSOCIATIONS Obtaining Fiduciary Powers § 550.125 How do I file the notice under...

The perioperative charge equivalence of interstitial brachytherapy and radical prostatectomy with 1-year followup.

PubMed

Kohan, A D; Armenakas, N A; Fracchia, J A

2000-02-01

We compare the comprehensive 1-year charges in a consecutive group of patients undergoing radical prostatectomy and transperineal interstitial brachytherapy for clinically localized prostate cancer at a single urban institution. A total of 60 consecutive men with clinically localized prostate cancer (T1-T2, N0, M0) were treated during a 15-month period with radical prostatectomy or interstitial brachytherapy. Hospital and outpatient records were analyzed for each patient in regard to preoperative, operative and postoperative charges. Parameters included number of encounters, diagnostic and therapeutic interventions, hospitalization and operative charges, and followup visits, diagnostic tests and interventions for 1 year. All charge calculations were based arbitrarily on the 1996 Medicare fee schedule, factoring in the mandated global charge reimbursement period of 90 days for both procedures. Of the patients 38 underwent radical prostatectomy (prostatectomy group) and 22 underwent interstitial brachytherapy (brachytherapy group). The brachytherapy group was older with higher pretreatment serum prostate specific antigen and clinical stage disease, and more frequently received neoadjuvant hormonal therapy compared to the prostatectomy group. The 2 groups were similar in Gleason score and, when applicable, duration of neoadjuvant hormonal therapy. Preoperative charges were 15.3% lower for prostatectomy than for brachytherapy (not statistically significant). Conversely, operative charges for prostatectomy were 13.5% higher (p = 0.04). The major difference among preoperative, operative and postoperative charges was for those incurred postoperatively by the brachytherapy group, which were 56.0% higher than those for the prostatectomy group ($2,285.20 versus $1,007.20, p = 0.0004). Transperineal interstitial seed implantation is perceived by many as more cost-effective than radical prostatectomy for patients with clinically localized prostate cancer. We demonstrated that

Design and optimization of a brachytherapy robot

NASA Astrophysics Data System (ADS)

Meltsner, Michael A.

Trans-rectal ultrasound guided (TRUS) low dose rate (LDR) interstitial brachytherapy has become a popular procedure for the treatment of prostate cancer, the most common type of non-skin cancer among men. The current TRUS technique of LDR implantation may result in less than ideal coverage of the tumor with increased risk of negative response such as rectal toxicity and urinary retention. This technique is limited by the skill of the physician performing the implant, the accuracy of needle localization, and the inherent weaknesses of the procedure itself. The treatment may require 100 or more sources and 25 needles, compounding the inaccuracy of the needle localization procedure. A robot designed for prostate brachytherapy may increase the accuracy of needle placement while minimizing the effect of physician technique in the TRUS procedure. Furthermore, a robot may improve associated toxicities by utilizing angled insertions and freeing implantations from constraints applied by the 0.5 cm-spaced template used in the TRUS method. Within our group, Lin et al. have designed a new type of LDR source. The "directional" source is a seed designed to be partially shielded. Thus, a directional, or anisotropic, source does not emit radiation in all directions. The source can be oriented to irradiate cancerous tissues while sparing normal ones. This type of source necessitates a new, highly accurate method for localization in 6 degrees of freedom. A robot is the best way to accomplish this task accurately. The following presentation of work describes the invention and optimization of a new prostate brachytherapy robot that fulfills these goals. Furthermore, some research has been dedicated to the use of the robot to perform needle insertion tasks (brachytherapy, biopsy, RF ablation, etc.) in nearly any other soft tissue in the body. This can be accomplished with the robot combined with automatic, magnetic tracking.

N-iodoacetyltyramine: Preparation and use in sup 125 I labeling by alkylation of sulfhydryl groups

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, C.M.; Mihal, K.A.; Krueger, R.J.

1989-06-01

Preparation and use of N-iodoacetyltyramine in generation of {sup 125}I-labeled compounds is described. The kinetics of alkylation of N-acetylcysteine by N-iodoacetyltyramine (k2 = 3.0 M-1 s-1) and N-chloroacetyltyramine (k2 = 0.12 M-1 s-1) indicate that N-iodoacetyltyramine is more useful for labeling sulfhydryl-containing compounds to high specific activity with {sup 125}I. Conditions for preparation of carrier-free {sup 125}I-labeled N-iodoacetyl-3-monoiodotyramine in 50% yield based on starting iodide are described. The high degree of group specificity of N-iodoacetyl-3-monoiodotyramine reaction with sulfhydryl groups is demonstrated by the high reactivity toward sulfhydryl-containing bovine serum albumin and low reactivity toward N-ethylmaleimide-blocked bovine serum albumin and IgG.more » {sup 125}I-labeled N-iodoacetyl-3-monoiodotyramine was also used to prepare an {sup 125}I-labeled ACTH derivative that retains full biological activity, further demonstrating the selectivity toward reactions with sulfhydryl groups.« less

DNA-PKcs Expression Is a Predictor of Biochemical Recurrence After Permanent Iodine 125 Interstitial Brachytherapy for Prostate Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Molina, Sarah; Department of Radiation Oncology, CHU/Université de Poitiers, Poitiers; Guerif, Stéphane

Purpose: Predictive factors for biochemical recurrence (BCR) in localized prostate cancer (PCa) after brachytherapy are insufficient to date. Cellular radiosensitivity depends on DNA double-strand breaks, mainly repaired by the nonhomologous end-joining (NHEJ) system. We analyzed whether the expression of NHEJ proteins can predict BCR in patients treated by brachytherapy for localized PCa. Methods and Materials: From 983 PCa cases treated by brachytherapy between March 2000 and March 2012, 167 patients with available biopsy material suitable for in situ analysis were included in the study. The median follow-up time was 47 months. Twenty-nine patients experienced BCR. All slides were reviewed to reassessmore » the Gleason score. Expression of the key NHEJ proteins DNA-PKcs, Ku70, and Ku80, and the proliferation marker Ki67, was studied by immunohistochemistry performed on tissue microarrays. Results: The Gleason scores after review (P=.06) tended to be associated with BCR when compared with the score initially reported (P=.74). Both the clinical stage (P=.02) and the pretreatment prostate-specific antigen level (P=.01) were associated with biochemical failure. Whereas the expression of Ku80 and Ki67 were not predictive of relapse, positive DNA-PKcs nuclear staining (P=.003) and higher Ku70 expression (P=.05) were associated with BCR. On multivariate analysis, among pretreatment variables, only DNA-PKcs (P=.03) and clinical stage (P=.02) remained predictive of recurrence. None of the patients without palpable PCa and negative DNA-PKcs expression experienced biochemical failure, compared with 32% of men with palpable and positive DNA-PKcs staining that recurred. Conclusions: Our results suggest that DNA-PKcs could be a predictive marker of BCR after brachytherapy, and this might be a useful tool for optimizing the choice of treatment in low-risk PCa patients.« less

[125I]2-(2-chloro-4-iodo-phenylamino)-5-methyl-pyrroline (LNP 911), a high-affinity radioligand selective for I1 imidazoline receptors.

PubMed

Greney, Hugues; Urosevic, Dragan; Schann, Stephan; Dupuy, Laurence; Bruban, Véronique; Ehrhardt, Jean-Daniel; Bousquet, Pascal; Dontenwill, Monique

2002-07-01

The I1 subtype of imidazoline receptors (I1R) is a plasma membrane protein that is involved in diverse physiological functions. Available radioligands used so far to characterize the I(1)R were able to bind with similar affinities to alpha2-adrenergic receptors (alpha2-ARs) and to I1R. This feature was a major drawback for an adequate characterization of this receptor subtype. New imidazoline analogs were therefore synthesized and the present study describes one of these compounds, 2-(2-chloro-4-iodo-phenylamino)-5-methyl-pyrroline (LNP 911), which was of high affinity and selectivity for the I1R. LNP 911 was radioiodinated and its binding properties characterized in different membrane preparations. Saturation experiments with [125I]LNP 911 revealed a single high affinity binding site in PC-12 cell membranes (K(D) = 1.4 nM; B(max) = 398 fmol/mg protein) with low nonspecific binding. [125I]LNP 911 specific binding was inhibited by various imidazolines and analogs but was insensitive to guanosine-5'-O-(3-thio)triphosphate. The rank order of potency of some competing ligands [LNP 911, PIC, rilmenidine, 4-chloro-2-(imidazolin-2-ylamino)-isoindoline (BDF 6143), lofexidine, and clonidine] was consistent with the definition of [125I]LNP 911 binding sites as I1R. However, other high-affinity I1R ligands (moxonidine, efaroxan, and benazoline) exhibited low affinities for these binding sites in standard binding assays. In contrast, when [125I]LNP 911 was preincubated at 4 degrees C, competition curves of moxonidine became biphasic. In this case, moxonidine exhibited similar high affinities on [125I]LNP 911 binding sites as on I1R defined with [125I]PIC. Moxonidine proved also able to accelerate the dissociation of [125I]LNP 911 from its binding sites. These results suggest the existence of an allosteric modulation at the level of the I1R, which seems to be corroborated by the dose-dependent enhancement by LNP 911 of the agonist effects on the adenylate cyclase pathway

Calibration of the Accuscan II In Vivo System for I-125 Thyroid Counting

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ovard R. Perry; David L. Georgeson

2011-07-01

This report describes the March 2011 calibration of the Accuscan II HpGe In Vivo system for I-125 thyroid counting. The source used for the calibration was a DOE manufactured Am-241/Eu-152 source contained in a 22 ml vial BEA Am-241/Eu-152 RMC II-1 with energies from 26 keV to 344 keV. The center of the detector housing was positioned 64 inches from the vault floor. This position places the approximate center line of the detector housing at the center line of the source in the phantom thyroid tube. The energy and efficiency calibration were performed using an RMC II phantom (Appendix J).more » Performance testing was conducted using source BEA Am-241/Eu-152 RMC II-1 and Validation testing was performed using an I-125 source in a 30 ml vial (I-125 BEA Thyroid 002) and an ANSI N44.3 phantom (Appendix I). This report includes an overview introduction and records for the energy/FWHM and efficiency calibration including performance verification and validation counting. The Accuscan II system was successfully calibrated for counting the thyroid for I-125 and verified in accordance with ANSI/HPS N13.30-1996 criteria.« less

Sci-Sat AM(2): Brachy-05: Dosimetry effects of the TG-43 approximations for two iodine seeds in LDR brachytherapy.

PubMed

Furstoss, C; Bertrand, M J; Poon, E; Reniers, B; Pignol, J P; Carrier, J F; Beaulieu, L; Verhaegen, F

2008-07-01

This work consists of studying the interseed and tissue composition effects for two model iodine seeds: the IBt Interseed-125 and the 6711 model seed. Three seeds were modeled with the MCNP MC code in a water sphere to evaluate the interseed effect. The dose calculated at different distances from the centre was compared to the dose summed when the seeds were simulated separately. The tissue composition effect was studied calculating the radial dose function for different tissues. Before carrying out post-implant studies, the absolute dose calculated by MC was compared to experiment results: with LiF TLDs in an acrylic breast phantom and with an EBT Gafchromic film placed in a water tank. Afterwards, the TG-43 approximation effects were studied for a prostate and breast post-implant. The interseed effect study shows that this effect is more important for model 6711 (15%) than for IBt (10%) due to the silver rod in 6711. For both seed models the variations of the radial dose function as a function of the tissue composition are quasi similar. The absolute dose comparisons between MC calculations and experiments give good agreement (inferior to 3% in general). For the prostate and breast post-implant studies, a 10% difference between MC calculations and the TG-43 is found for both models of seeds. This study shows that the differences in dose distributions between TG43 and MC are quite similar for the two models of seeds and are about 10% for the studied post-implant treatments. © 2008 American Association of Physicists in Medicine.

Repeated iodine-125 seed implantations combined with external beam radiotherapy for the treatment of locally recurrent or metastatic stage III/IV non-small cell lung cancer: a retrospective study.

PubMed

Li, Wei; Dan, Gang; Jiang, Jianqing; Zheng, Yifeng; Zheng, Xiushan; Deng, Dan

2016-09-13

Recurrent or metastatic lung cancer is difficult to manage. This retrospective study aimed to assess the efficacy of repeated iodine-125 seed implantations combined with external beam radiotherapy (EBRT) for locally recurrent or metastatic stage-III/IV non-small cell lung cancer (NSCLC). Eighteen previously treated stage-III/IV NSCLC patients with local or metastatic recurrences underwent 1-to-3 iodine-125 implantations. Six of these patients received palliative EBRT and six patients received combined chemotherapy using gemcitabine and cisplatin. Near-term treatment efficacy was evaluated 3 months after seed implantation by comparing changes in tumor size on computed tomography images; the evaluated outcomes were complete response, partial response, stable disease, and local tumor control rate. Long-term efficacy was assessed based on 1- and 2-year survival rates. Patients were followed up for 6 to 50 months. The overall (i.e., complete + partial) response rate was 87.4 %. The local control rates after the first, second, and third years were 94.1, 58.8 and 41.2 %, respectively. The results of this study demonstrated that repeated implantation of radioactive particles combined with EBRT is a safe treatment that effectively controlled local recurrence and metastasis of stage III/IV NSCLC.

In vivo binding of /sup 125/I-LSD to serotonin 5-HT/sub 2/ receptors in mouse brain

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hartig, P.R.; Scheffel, U., Frost, J.J.; Wagner, H.N. Jr.

The binding of /sup 125/I-LSD (2-(/sup 125/I)-lysergic acid diethylamide) was studied in various mouse brain regions following intravenous injection of the radioligand. The high specific activity of /sup 125/I-LSD enabled the injection of low mass doses (14ng/kg), which are well below the threshold for induction of any known physiological effect of the probe. The highest levels of /sup 125/I-LSD binding were found in the frontal cortex, olfactory tubercles, extra-frontal cortex and striatum while the lowest level was found in the cerebellum. Binding was saturable in the frontal cortex but increased linearly in the cerebellum with increasing doses of /sup 125/I-LSD.more » Serotonergic compounds potently inhibited /sup 125/I-LSD binding in cortical regions, olfactory tubercles, and hypothalamus but had no effect in the cerebellum. Dopaminergic compounds caused partial inhibition of binding in the striatum while adrenergic compounds were inactive. From these studies the authors conclude that /sup 125/I-LSD labels serotonin 5-HT/sub 2/ receptor sites in cortical regions with no indication that other receptor sites are labeled. In the olfactory tubercles and hypothalamus, /sup 125/I-LSD labeling occurs predominantly or entirely at serotonic 5-HT/sub 2/ sites. In the striatum, /sup 125/I-LSD labels approximately equal proportions of serotonergic and dopaminergic sites. These data indicate that /sup 125/I-LSD labels serotonin receptors in vivo and suggests that appropriate derivatives of 2I-LSD may prove useful for tomographic imaging of serotonin 5-HT/sub 2/ receptors in the mammalian cortex.« less

Low-dose rate prostate brachytherapy is well tolerated in patients with a history of inflammatory bowel disease

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peters, Christopher A.; Cesaretti, Jamie A.; Stone, Nelson N.

2006-10-01

Purpose: We report on the follow-up of 24 patients with a prior history of inflammatory bowel disease (IBD) treated with brachytherapy for early-stage prostate cancer. Methods and Materials: Twenty-four patients with a history of inflammatory bowel disease (17 with ulcerative colitis (UC), 7 with Crohn's disease [CD]) underwent prostate brachytherapy between 1992 and 2004. Fifteen patients were treated with I-125 implantation and 6 patients were treated with Pd-103 alone or in combination with 45 Gy external beam radiation. Charts were reviewed for all patients, and all living patients were contacted by phone. National Cancer Institute common toxicity scores for proctitismore » were assigned to all patients. Actuarial risk of late toxicity was calculated by the Kaplan-Meier method. Statistical analysis was performed using SPSS software. Follow-up ranged from 3 to 126 months (median, 48.5 months; mean, 56.8 months). Results: None of the patients experienced Grade 3 or 4 rectal toxicity. Four patients experienced Grade 2 late rectal toxicity. The 5-year actuarial freedom from developing late Grade 2 rectal toxicity was 81%. At a median follow-up of 48.5 months, 23 patients were alive and had no evidence of disease with a median prostate-specific antigen for the sample of 0.1 ng/mL (range, <0.05-0.88 ng/mL). One patient died of other causes unrelated to his prostate cancer. Conclusions: Prostate brachytherapy is well tolerated in patients with a history of controlled IBD. Therefore, brachytherapy should be considered a viable therapeutic option in this patient population.« less

Vision Loss Following Episcleral Brachytherapy for Uveal Melanoma: Development of a Vision Prognostication Tool.

PubMed

Aziz, Hassan A; Singh, Nakul; Bena, James; Wilkinson, Allan; Singh, Arun D

2016-06-01

Vision loss following episcleral brachytherapy for uveal melanoma is difficult to predict for individual patients. To generate a risk calculator for vision loss following episcleral brachytherapy for uveal melanoma. A retrospective review of data was conducted at a multispecialty tertiary care center in Cleveland, Ohio. All patients with primary ciliary body or choroidal melanoma treated with iodine 125 or ruthenium 106 episcleral brachytherapy between January 1, 2004, and December 30, 2013, were included. Univariate and multivariable Cox proportional hazards were used to determine the influence of baseline patient factors on vision loss. Kaplan-Meier curves (log-rank analyses) were used to estimate freedom from vision loss. Bootstrap resampling was performed to bias correct this estimate. Vision loss (to visual acuity [VA] worse than 20/50 and worse than 20/200). A total of 311 patients were included in the study, with a mean (SD) age of 62 (14.7) years at start of treatment and a median follow-up of 36 months (interquartile range, 18-60 months). At presentation, VA was better than or equal to 20/50 in 199 patients (64%) and better than or equal to 20/200 in 289 patients (93%). By Kaplan-Meier analysis, VA less than 20/200 at 3 years was not associated with sex, diabetes, systemic hypertension, or hypercholesterolemia but was associated with history of ocular comorbidities, type of isotope (ruthenium 106 or iodine 125), and initial VA ( >20/50 or <20/50). By multivariable analysis, age (hazard ratio [HR], 0.97; 95% CI, 0.94-1.00; P = .06), largest basal diameter (HR, 1.25; 95% CI, 1.16-1.34; P = <.001), total radiation dose to the fovea (HR, 1.03; 95% CI, 1.01-1.04; P = .001) and optic disc (HR, 1.01; 95% CI, 1.00-1.01; P = .005), and initial VA worse than 20/50 (HR, 1.85; 95% CI, 1.20-2.85; P = .005) were predictive of vision loss to a VA of less than 20/200. The concordance index for the full data set was 0.77. Using these data, an online

Absolute measurement of LDR brachytherapy source emitted power: Instrument design and initial measurements.

PubMed

Malin, Martha J; Palmer, Benjamin R; DeWerd, Larry A

2016-02-01

Energy-based source strength metrics may find use with model-based dose calculation algorithms, but no instruments exist that can measure the energy emitted from low-dose rate (LDR) sources. This work developed a calorimetric technique for measuring the power emitted from encapsulated low-dose rate, photon-emitting brachytherapy sources. This quantity is called emitted power (EP). The measurement methodology, instrument design and performance, and EP measurements made with the calorimeter are presented in this work. A calorimeter operating with a liquid helium thermal sink was developed to measure EP from LDR brachytherapy sources. The calorimeter employed an electrical substitution technique to determine the power emitted from the source. The calorimeter's performance and thermal system were characterized. EP measurements were made using four (125)I sources with air-kerma strengths ranging from 2.3 to 5.6 U and corresponding EPs of 0.39-0.79 μW, respectively. Three Best Medical 2301 sources and one Oncura 6711 source were measured. EP was also computed by converting measured air-kerma strengths to EPs through Monte Carlo-derived conversion factors. The measured EP and derived EPs were compared to determine the accuracy of the calorimeter measurement technique. The calorimeter had a noise floor of 1-3 nW and a repeatability of 30-60 nW. The calorimeter was stable to within 5 nW over a 12 h measurement window. All measured values agreed with derived EPs to within 10%, with three of the four sources agreeing to within 4%. Calorimeter measurements had uncertainties ranging from 2.6% to 4.5% at the k = 1 level. The values of the derived EPs had uncertainties ranging from 2.9% to 3.6% at the k = 1 level. A calorimeter capable of measuring the EP from LDR sources has been developed and validated for (125)I sources with EPs between 0.43 and 0.79 μW.

p-( sup 125 I)iodoclonidine is a partial agonist at the alpha 2-adrenergic receptor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gerhardt, M.A.; Wade, S.M.; Neubig, R.R.

1990-08-01

The binding properties of p-(125I)iodoclonidine (( 125I)PIC) to human platelet membranes and the functional characteristics of PIC are reported. (125I)PIC bound rapidly and reversibly to platelet membranes, with a first-order association rate constant (kon) at room temperature of 8.0 +/- 2.7 x 10(6) M-1 sec-1 and a dissociation rate constant (koff) of 2.0 +/- 0.8 x 10(-3) sec-1. Scatchard plots of specific (125I)PIC binding (0.1-5 nM) were linear, with a Kd of 1.2 +/- 0.1 nM. (125I)PIC bound to the same number of high affinity sites as the alpha 2-adrenergic receptor (alpha 2-AR) full agonist (3H) bromoxidine (UK14,304), which representedmore » approximately 40% of the sites bound by the antagonist (3H)yohimbine. Guanosine 5'-(beta, gamma-imido)triphosphate greatly reduced the amount of (125I)PIC bound (greater than 80%), without changing the Kd of the residual binding. In competition experiments, the alpha 2-AR-selective ligands yohimbine, bromoxidine, oxymetazoline, clonidine, p-aminoclonidine, (-)-epinephrine, and idazoxan all had Ki values in the low nanomolar range, whereas prazosin, propranolol, and serotonin yielded Ki values in the micromolar range. Epinephrine competition for (125I)PIC binding was stereoselective. Competition for (3H)bromoxidine binding by PIC gave a Ki of 1.0 nM (nH = 1.0), whereas competition for (3H)yohimbine could be resolved into high and low affinity components, with Ki values of 3.7 and 84 nM, respectively. PIC had minimal agonist activity in inhibiting adenylate cyclase in platelet membranes, but it potentiated platelet aggregation induced by ADP with an EC50 of 1.5 microM. PIC also inhibited epinephrine-induced aggregation, with an IC50 of 5.1 microM. Thus, PIC behaves as a partial agonist in a human platelet aggregation assay. (125I)PIC binds to the alpha 2B-AR in NG-10815 cell membranes with a Kd of 0.5 +/- 0.1 nM.« less

Use of 2-(/sup 125/I)iodomelatonin to characterize melatonin binding sites in chicken retina

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dubocovich, M.L.; Takahashi, J.S.

2-(/sup 125/I)Iodomelatonin binds with high affinity to a site possessing the pharmacological characteristics of a melatonin receptor in chicken retinal membranes. The specific binding of 2-(/sup 125/I)iodomelatonin is stable, saturable, and reversible. Saturation experiments indicated that 2-(/sup 125/I)iodomelatonin labeled a single class of sites with an affinity constant (Kd) of 434 +/- 56 pM and a total number of binding sites (Bmax) of 74.0 +/- 13.6 fmol/mg of protein. The affinity constant obtained from kinetic analysis was in close agreement with that obtained in saturation experiments. Competition experiments showed a monophasic reduction of 2-(/sup 125/I)iodomelatonin binding with a pharmacological ordermore » of indole amine affinities characteristic of a melatonin receptor: 2-iodomelatonin greater than 6-chloromelatonin greater than or equal to melatonin greater than or equal to 6,7-dichloro-2-methylmelatonin greater than 6-hydroxymelatonin greater than or equal to 6-methoxymelatonin much greater than N-acetyltryptamine greater than N-acetyl-5-hydroxytryptamine greater than 5-methoxytryptamine greater than 5-hydroxytryptamine (inactive). The affinities of these melatonin analogs in competing for 2-(/sup 125/I)iodomelatonin binding sites were correlated closely with their potencies for inhibition of the calcium-dependent release of (3H)dopamine from chicken and rabbit retinas, indicating association of the binding site with a functional response regulated by melatonin. The results indicate that 2-(/sup 125/I)iodomelatonin is a selective, high-affinity radioligand for the identification and characterization of melatonin receptor sites.« less

Parameters predicting for prostate specific antigen response rates at one year post low-dose-rate intraoperative prostate brachytherapy

PubMed Central

Meyer, Tyler; Sia, Michael; Angyalfi, Steve; Husain, Siraj

2017-01-01

Purpose To develop a model for prostate specific antigen (PSA) values at one year among patients treated with intraoperatively planned 125I prostate brachytherapy (IOPB). Material and methods Four hundred and deven patients treated with IOPB for prostate adenocarcinoma were divided into four groups: those with PSA values ≥ 3 ng/ml; < 3 and ≥ 2; < 2 and ≥ 1 or PSA < 1 between 10.5 and 14.5 months post implantation (1yPSA). Ordinal regression analysis was then performed between patient, tumor, and treatment characteristics. 1yPSA values were also compared with toxicity outcomes. Results Median 1yPSA was 0.77 (0.04-17.36). Thirty-two patients (8%) had a PSA ≥ 3; 35 (9%) had PSA < 3, ≥ 2; 87 (21%) had PSA < 2, ≥ 1, and most patients 254 (62%) had PSA < 1. PSA response was independent of gland volume, Gleason score, clinical stage, seed activity, V90, V200, D90, or number of needles and seeds used. Older patients had significantly lower 1yPSA; median ages 65.1 (46.5-81.0), 62.1 (50.4-79.5), 60.5 (47.1-80.3), and 58.1 (45.1-74.2) years for each of the 1yPSA groups respectively (p < 0.001). Also, both implant V150 (p < 0.001) and initial PSA values (p = 0.04) were predictive of 1yPSA values. There was no correlation between 1yPSA values and toxicity encountered. Conclusions PSA response at 1 year post IOPB appears to be dependent on patient age, initial PSA, and implant V150. Our results provide reassurance that parameters other than biochemical failure influence 1yPSA values. PMID:28533796

[Brachytherapy training].

PubMed

Hannoun-Lévi, J-M; Marchesi, V; Peiffert, D

2013-04-01

Treatment technique training needs theoretical and practical knowledge allowing proposing the right treatment for the right patient, but also allowing performing the technical gesture in the best conditions for an optimal result with a maximal security. The evolution of the brachytherapy techniques needs the set up of specific theoretical and practical training sessions. The present article focuses on the importance of the brachytherapy training as well as the different means currently available for the young radiation oncologist community for perfecting their education. National and international trainings are presented. The role of the simulation principle in the frame of brachytherapy is also discussed. Even if brachytherapy is not always an easy technique, its efficacy and its medico-economical impact need to be passed down to motivated students with the implementation of relevant educational means. Copyright © 2013 Société française de radiothérapie oncologique (SFRO). Published by Elsevier SAS. All rights reserved.

[125I]Iodo-ASEM, a specific in vivo radioligand for α7-nAChR

PubMed Central

Gao, Yongjun; Mease, Ronnie C.; Olson, Thao T.; Kellar, Kenneth J.; Dannals, Robert F.; Pomper, Martin G.; Horti, Andrew G.

2014-01-01

[125I]Iodo-ASEM, a new radioligand with high affinity and selectivity for α7-nAChRs (Ki = 0.5 nM; α7/α4β2 = 3,414), has been synthesized in radiochemical yield of 33 ± 6% from the corresponding di-butyltriazene derivative and at high specific radioactivity (1,600 Ci/mmol; 59.2 MBq/μmol). [125I]Iodo-ASEM readily entered the brains of normal CD-1 mice and specifically and selectively labeled cerebral α7-nAChRs. [125I]iodo-ASEM is a new useful tool for studying α7-nAChR. PMID:25687449

[Radiolabelling and assay of Chinese agkistrodon acutus venom with carrier-free Na 125I].

PubMed

Gong, Y; Deng, C; Li, S; Li, L; Guan, J

1995-03-01

Chinese agkistroden acutus venom (CAAV) was radiolabelled with carrier-free Na 125I by the method of Iodogen. The specific activity and radiochemical purity for radiolabelled products were 4236.5 x 10(10) Bq/mmol and 98%, respectively. Each CAAV molecule carried 0.52 125I atom. Physical and chemical characterization of radiolabelled CAAV was similar to unradiolabelled CAAV. Binding analysis showed that 125I-CAAV was bound to platelet in a saturable manner. Binding sites per platelet were 13,255 +/- 6292/platelet. The dissociation constant (Kd) was 3.2 +/- 0.69 x 10(-10) mol/L. These results are similar to binding sites of other snake venom on platelet. The investigation showed that radiolabelled CAAV made by our laboratory was useful for radioligand binding assay.

Measurement of /sup 125/I-low density lipoprotein uptake in selected tissues of the squirrel monkey by quantitative autoradiography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tompkins, R.G.; Schnitzer, J.J.; Yarmush, M.L.

1988-09-01

A recently developed technique of absolute quantitative light microscopic autoradiography of /sup 125/I-labeled proteins in biologic specimens was used to measure /sup 125/I-low density lipoprotein (/sup 125/I-LDL) concentration levels in various tissues of the squirrel monkey after 30 minutes of in vivo LDL circulation. Liver and adrenal cortex exhibited high /sup 125/I-LDL concentrations, presumably because of binding to specific cell surface receptors and/or internalization in vascular beds with high permeability to LDL. High tissue concentrations of LDL were associated with the zona fasciculata and reticularis of the adrenal cortex and the interstitial cells of Leydig in the testis; significantly lowermore » levels of /sup 125/I-LDL were observed in the adrenal medulla, the zona glomerulosa, and germinal centers of the testis. Contrary to previous reports, low /sup 125/I-LDL concentrations were observed throughout the gastrointestinal tract and in lymph nodes. In addition, multiple arterial intramural focal areas of high /sup 125/I-LDL concentrations were identified in arteries supplying the adrenal gland, lymph node, small bowel, and liver.« less

MRI-guided brachytherapy

PubMed Central

Tanderup, Kari; Viswanathan, Akila; Kirisits, Christian; Frank, Steven J.

2014-01-01

The application of MRI-guided brachytherapy has demonstrated significant growth during the last two decades. Clinical improvements in cervix cancer outcomes have been linked to the application of repeated MRI for identification of residual tumor volumes during radiotherapy. This has changed clinical practice in the direction of individualized dose administration, and mounting evidence of improved clinical outcome with regard to local control, overall survival as well as morbidity. MRI-guided prostate HDR and LDR brachytherapy has improved the accuracy of target and organs-at-risk (OAR) delineation, and the potential exists for improved dose prescription and reporting for the prostate gland and organs at risk. Furthermore, MRI-guided prostate brachytherapy has significant potential to identify prostate subvolumes and dominant lesions to allow for dose administration reflecting the differential risk of recurrence. MRI-guided brachytherapy involves advanced imaging, target concepts, and dose planning. The key issue for safe dissemination and implementation of high quality MRI-guided brachytherapy is establishment of qualified multidisciplinary teams and strategies for training and education. PMID:24931089

SU-F-BRA-04: Prostate HDR Brachytherapy with Multichannel Robotic System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Joseph, F Maria; Podder, T; Yu, Y

Purpose: High-dose-rate (HDR) brachytherapy is gradually becoming popular in treating patients with prostate cancers. However, placement of the HDR needles at desired locations into the patient is challenging. Application of robotic system may improve the accuracy of the clinical procedure. This experimental study is to evaluate the feasibility of using a multichannel robotic system for prostate HDR brachytherapy. Methods: In this experimental study, the robotic system employed was a 6-DOF Multichannel Image-guided Robotic Assistant for Brachytherapy (MIRAB), which was designed and fabricated for prostate seed implantation. The MIRAB has the provision of rotating 16 needles while inserting them. Ten prostatemore » HDR brachytherapy needles were simultaneously inserted using MIRAB into a commercially available prostate phantom. After inserting the needles into the prostate phantom at desired locations, 2mm thick CT slices were obtained for dosimetric planning. HDR plan was generated using Oncetra planning system with a total prescription dose of 34Gy in 4 fractions. Plan quality was evaluated considering dose coverage to prostate and planning target volume (PTV), with 3mm margin around prostate, as well as the dose limit to the organs at risk (OARs) following the American Brachytherapy Society (ABS) guidelines. Results: From the CT scan, it is observed that the needles were inserted straight into the desired locations and they were adequately spaced and distributed for a clinically acceptable HDR plan. Coverage to PTV and prostate were about 91% (V100= 91%) and 96% (V100=96%), respectively. Dose to 1cc of urethra, rectum, and bladder were within the ABS specified limits. Conclusion: The MIRAB was able to insert multiple needles simultaneously into the prostate precisely. By controlling the MIRAB to insert all the ten utilized needles into the prostate phantom, we could achieve the robotic HDR brachytherapy successfully. Further study for assessing the system�

Specific uptake, dissociation, and degradation of /sup 125/I-labeled insulin in isolated turtle (Chrysemys dorbigni) thyroid glands

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marques, M.; da Silva, R.S.; Turyn, D.

1985-11-01

Thyroid glands from turtles (Chrysemys dorbigni) pretreated with potassium iodide were incubated with /sup 125/I-insulin in the presence or absence of unlabeled insulin, in order to study its specific uptake. At 24 degrees, the specific uptake reached a plateau at 180 min of incubation. The dose of bovine insulin that inhibited 50% of the /sup 125/I-insulin uptake was 2 micrograms/ml of incubation medium. Most of the radioactive material (71%) extracted from the gland, after 30 min incubation with /sup 125/I-insulin, eluted in the same position as labeled insulin on Sephadex G-50. Only 24% eluted in the salt position. After 240more » min incubation, increased amount of radioactivity appeared in the Na/sup 125/I position. When bovine insulin was added together with the labeled hormone, a substantial reduction of radioactivity was observed in the insulin and Na/sup 125/I elution positions. Dissociation studies were performed at 6 degrees in glands preincubated with /sup 125/I-insulin either at 24 or 6 degrees. The percentage of trichloroacetic acid (TCA)-soluble radioactive material in the dissociation medium increased with incubation time at both temperatures. However, the degradation activity was lower at 6 than at 24 degrees. The addition of bovine insulin to the incubation buffer containing /sup 125/I-insulin reduced the radioactive degradation products in the dissociated medium. Chloroquine or bacitracin inhibited the degradation activity. Incubation of thyroid glands with /sup 125/I-hGH or /sup 125/I-BSA showed values of uptake, dissociation, and degradation similar to those experiments in which an excess of bovine insulin was added together with the labeled hormone. Thus, by multiple criteria, such as specific uptake, dissociation, and degradation, the presence of insulin-binding sites in the turtle thyroid gland may be suggested.« less

Apparatus and method for high dose rate brachytherapy radiation treatment

DOEpatents

Macey, Daniel J.; Majewski, Stanislaw; Weisenberger, Andrew G.; Smith, Mark Frederick; Kross, Brian James

2005-01-25

A method and apparatus for the in vivo location and tracking of a radioactive seed source during and after brachytherapy treatment. The method comprises obtaining multiple views of the seed source in a living organism using: 1) a single PSPMT detector that is exposed through a multiplicity of pinholes thereby obtaining a plurality of images from a single angle; 2) a single PSPMT detector that may obtain an image through a single pinhole or a plurality of pinholes from a plurality of angles through movement of the detector; or 3) a plurality of PSPMT detectors that obtain a plurality of views from different angles simultaneously or virtually simultaneously. The plurality of images obtained from these various techniques, through angular displacement of the various acquired images, provide the information required to generate the three dimensional images needed to define the location of the radioactive seed source within the body of the living organism.

Synthesis and evaluation of [125I]I-TSA as a brain nicotinic acetylcholine receptor alpha7 subtype imaging agent.

PubMed

Ogawa, Mikako; Tatsumi, Ryo; Fujio, Masakazu; Katayama, Jiro; Magata, Yasuhiro

2006-04-01

Some in vitro investigations have suggested that the nicotinic acetylcholine receptor (nAChR) alpha7 subtype is implicated in Alzheimer's disease, schizophrenia and others. Recently, we developed (R)-3'-(5-bromothiophen-2-yl)spiro[1-azabicyclo[2.2.2]octane-3,5'-[1',3']oxazolidin]-2'-one (Br-TSA), which has a high affinity and selectivity for alpha7 nAChRs. Therefore we synthesized (R)-3'-(5-[125I]iodothiophen-2-yl)spiro[1-azabicyclo[2.2.2]octane-3,5'-[1',3']oxazolidin]-2'-one ([125I]I-TSA) and evaluated its potential for the in vivo detection of alpha7 nAChR in brain. In vitro binding affinity of I-TSA was measured in rat brain homogenates. Radioiodination was accomplished by a Br-I exchange reaction. Biodistribution studies were undertaken in mice by tail vein injection of [(125)I]I-TSA. In vivo receptor blocking studies were carried out by treating mice with methyllycaconitine (MLA; 5 nmol/5 mul, i.c.v.) or nonradioactive I-TSA (50 micromol/kg, i.v.). I-TSA exhibited a high affinity and selectivity for the alpha7 nAChR (K(i) for alpha7 nAChR = 0.54 nM). Initial uptake in the brain was high (4.42 %dose/g at 5 min), and the clearance of radioactivity was relatively slow in the hippocampus (alpha7 nAChR-rich region) and was rather rapid in the cerebellum (alpha7 nAChR poor region). The hippocampus to cerebellum uptake ratio was 0.9 at 5 min postinjection, but it was increased to 1.8 at 60 min postinjection. Although the effect was not statistically significant, administration of I-TSA and MLA decreased the accumulation of radioactivity in hippocampus. Despite its high affinity and selectivity, [125I]I-TSA does not appear to be a suitable tracer for in vivo alpha7 nAChR receptor imaging studies due to its high nonspecific binding. Further structural optimization is needed.

Polymer gel water equivalence and relative energy response with emphasis on low photon energy dosimetry in brachytherapy

NASA Astrophysics Data System (ADS)

Pantelis, E.; Karlis, A. K.; Kozicki, M.; Papagiannis, P.; Sakelliou, L.; Rosiak, J. M.

2004-08-01

The water equivalence and stable relative energy response of polymer gel dosimeters are usually taken for granted in the relatively high x-ray energy range of external beam radiotherapy based on qualitative indices such as mass and electron density and effective atomic number. However, these favourable dosimetric characteristics are questionable in the energy range of interest to brachytherapy especially in the case of lower energy photon sources such as 103Pd and 125I that are currently utilized. In this work, six representative polymer gel formulations as well as the most commonly used experimental set-up of a LiF TLD detector-solid water phantom are discussed on the basis of mass attenuation and energy absorption coefficients calculated in the energy range of 10 keV-10 MeV with regard to their water equivalence as a phantom and detector material. The discussion is also supported by Monte Carlo simulation results. It is found that water equivalence of polymer gel dosimeters is sustained for photon energies down to about 60 keV and no corrections are needed for polymer gel dosimetry of 169Yb or 192Ir sources. For 125I and 103Pd sources, however, a correction that is source-distance dependent is required. Appropriate Monte Carlo results show that at the dosimetric reference distance of 1 cm from a source, these corrections are of the order of 3% for 125I and 2% for 103Pd. These have to be compared with corresponding corrections of up to 35% for 125I and 103Pd and up to 15% even for the 169Yb energies for the experimental set-up of the LiF TLD detector-solid water phantom.

Polymer gel water equivalence and relative energy response with emphasis on low photon energy dosimetry in brachytherapy.

PubMed

Pantelis, E; Karlis, A K; Kozicki, M; Papagiannis, P; Sakelliou, L; Rosiak, J M

2004-08-07

The water equivalence and stable relative energy response of polymer gel dosimeters are usually taken for granted in the relatively high x-ray energy range of external beam radiotherapy based on qualitative indices such as mass and electron density and effective atomic number. However, these favourable dosimetric characteristics are questionable in the energy range of interest to brachytherapy especially in the case of lower energy photon sources such as 103Pd and 125I that are currently utilized. In this work, six representative polymer gel formulations as well as the most commonly used experimental set-up of a LiF TLD detector-solid water phantom are discussed on the basis of mass attenuation and energy absorption coefficients calculated in the energy range of 10 keV-10 MeV with regard to their water equivalence as a phantom and detector material. The discussion is also supported by Monte Carlo simulation results. It is found that water equivalence of polymer gel dosimeters is sustained for photon energies down to about 60 keV and no corrections are needed for polymer gel dosimetry of 169Yb or 192Ir sources. For 125I and 103Pd sources, however, a correction that is source-distance dependent is required. Appropriate Monte Carlo results show that at the dosimetric reference distance of 1 cm from a source, these corrections are of the order of 3% for 125I and 2% for 103Pd. These have to be compared with corresponding corrections of up to 35% for 125I and 103Pd and up to 15% even for the 169Yb energies for the experimental set-up of the LiF TLD detector-solid water phantom.

New era of electronic brachytherapy

PubMed Central

Ramachandran, Prabhakar

2017-01-01

Traditional brachytherapy refers to the placement of radioactive sources on or inside the cancer tissues. Based on the type of sources, brachytherapy can be classified as radionuclide and electronic brachytherapy. Electronic brachytherapy uses miniaturized X-ray sources instead of radionuclides to deliver high doses of radiation. The advantages of electronic brachytherapy include low dose to organs at risk, reduced dose to treating staff, no leakage radiation in off state, less shielding, and no radioactive waste. Most of these systems operate between 50 and 100 kVp and are widely used in the treatment of skin cancer. Intrabeam, Xoft and Papillon systems are also used in the treatment of intra-operative radiotherapy to breast in addition to other treatment sites. The rapid fall-off in the dose due to its low energy is a highly desirable property in brachytherapy and results in a reduced dose to the surrounding normal tissues compared to the Ir-192 source. The Xoft Axxent brachytherapy system uses a 2.25 mm miniaturized X-ray tube and the source almost mimics the high dose rate Ir-192 source in terms of dose rate and it is the only electronic brachytherapy system specifically used in the treatment of cervical cancers. One of the limiting factors that impede the use of electronic brachytherapy for interstitial application is the source dimension. However, it is highly anticipated that the design of miniaturized X-ray tube closer to the dimension of an Ir-192 wire is not too far away, and the new era of electronic brachytherapy has just begun. PMID:28529679

Air kerma and absorbed dose standards for reference dosimetry in brachytherapy

PubMed Central

2014-01-01

This article reviews recent developments in primary standards for the calibration of brachytherapy sources, with an emphasis on the currently most common photon-emitting radionuclides. The introduction discusses the need for reference dosimetry in brachytherapy in general. The following section focuses on the three main quantities, i.e. reference air kerma rate, air kerma strength and absorbed dose rate to water, which are currently used for the specification of brachytherapy photon sources and which can be realized with primary standards from first principles. An overview of different air kerma and absorbed dose standards, which have been independently developed by various national metrology institutes over the past two decades, is given in the next two sections. Other dosimetry techniques for brachytherapy will also be discussed. The review closes with an outlook on a possible transition from air kerma to absorbed dose to water-based calibrations for brachytherapy sources in the future. PMID:24814696

Synthesis of 4-(3'-[125I]iodoanilino)-6,7-dialkoxyquinazolines:radiolabeled epidermal growth factor receptor tyrosine kinaseinhibitors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lim, John K.; Negash, Kitaw; Hanrahan, Stephen M.

1999-10-25

The preparation of two radioiodinated analogs of theepidermal growth factor receptor tyrosine kinase (EGFrTK) inhibitorPD153035(4-(3'-bromoanilino)-6,7-dimethoxyquinazoline) are reportedherein. The two analogs,4-(3'-[125I]iodoanilino)-6,7-dimethoxyquinazoline and4-(3'-[125I]iodoanilino)-6,7-diethoxyquinazoline, were synthesizedviaiododestannylation of the corresponding4-(3'-trimethylstannylanilino)-6,7-dialkoxyquinazolines to form thedesired I-125 labeled products in good yield and high radiochemicalpurity (>99 percent).

An experimental palladium-103 seed (OptiSeedexp) in a biocompatible polymer without a gold marker: characterization of dosimetric parameters including the interseed effect.

PubMed

Abboud, F; Scalliet, P; Vynckier, S

2008-12-01

Permanent implantation of 125I (iodine) or 103Pd (palladium) sources is a popular treatment option in the management of early stage prostate cancer. New sources are being developed, some of which are being marketed for different clinical applications. A new technique of adjuvant stereotactic permanent seed breast implant, similar to that used in the treatment of prostate cancer, has been proposed by [N. Jansen et al., Int. J. Radiat. Oncol. Biol. Phys. 67, 1052-1058 (2007)] with encouraging results. The presence of artifacts from the metallic seeds, however, can disturb follow-up imaging. The development of plastic seeds has reduced these artifacts. This paper presents a feasibility study of the advantages of palladium-103 seeds, encapsulated with a biocompatible polymer, for future clinical applications, and on the effect of the gold marker on the dosimetric characteristics of such seeds. Experimental palladium seeds, OptiSeedexp, were manufactured by International Brachytherapy (IBt), Seneffe, Belgium, from a biocompatible polymer, including the marker. Apart from the absence of a gold marker, the studied seed has an identical design to the OptiSeed103 [Phys. Med. Biol. 50, 1493-1504 (2005)]; [Appl. Radiat. Isot. 63, 311-321 (2005)]. Polymer encapsulation was preferred by IBt in order to reduce the quantity of radioactive material needed for a given dose rate and to reduce the anisotropy of the radiation field around the seed. In addition, this design is intended to decrease the interseed effects that can occur as a result of the marker and the encapsulation. Dosimetric measurements were performed using LiF thermoluminescent dosimeters (1 mm3) in solid water phantoms (WT1). Measured data were compared to Monte Carlo simulated data in solid water using the MCNP code, version 4C. Updated cross sections [Med. Phys. 30, 701-711 (2003)] were used. As the measured and calculated data were in agreement, Monte Carlo calculations were then performed in liquid water to

Iodine 125 source in interstitial tumor therapy. Clinical and biological considerations.

PubMed

Kim, J H; Hilaris, B

1975-01-01

Our clinical experience with interstitial tumor therapy is presented in 2 groups of patients: 98 patients with metastatic carcinoma in neck lymph nodes implanted with iodine 125, iridium 192 or radon 222 encapsulated sources, and 105 patients with primary unresectable lung tumors, which were implanted either with radon 222 or iodine 125 seeds. The local tumor control rates with iodine 125, radon 222 and iridium 192 were 78 per cent (38/49), 65 per cent (15/23) and 58 per cent (7/12), while the local complication rates were 17 per cent, 35 per cent and 43 per cent, respectively. An analysis of the tumor control rate as a function of the implanted tumor dose shows that the iodine 125 implants with a delivery of the minimal effective tumor dose of 16,000 rads have a higher therapeutic effect than either radon 222 or iridium 192. The results of the patients with unresectable lung tumors similarly show that the implants with iodine 125 sources are superior to those with radon 222. The advantages could stem from the better spatial dose distribution, and from radiobiologic considerations associated with low dose rates, continous irradiation, and possibly gains in RBE. There present clinical data clearly demonstrate that iodine 125 seeds have a higher therapeutic ratio than radon 222 seeds. There are, in addition, distinct physical advantages making iodine 125 an attractive substitute for radon 222 for the interstitial implantation of malignant tumors.

Image Guided Cervical Brachytherapy: 2014 Survey of the American Brachytherapy Society

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grover, Surbhi, E-mail: Surbhi.grover@uphs.upenn.edu; Harkenrider, Matthew M.; Cho, Linda P.

Purpose: To provide an update of the 2007 American brachytherapy survey on image-based brachytherapy, which showed that in the setting of treatment planning for gynecologic brachytherapy, although computed tomography (CT) was often used for treatment planning, most brachytherapists used point A for dose specification. Methods and Materials: A 45-question electronic survey on cervical cancer brachytherapy practice patterns was sent to all American Brachytherapy Society members and additional radiation oncologists and physicists based in the United States between January and September 2014. Responses from the 2007 survey and the present survey were compared using the χ{sup 2} test. Results: There weremore » 370 respondents. Of those, only respondents, not in training, who treat more than 1 cervical cancer patient per year and practice in the United States, were included in the analysis (219). For dose specification to the target (cervix and tumor), 95% always use CT, and 34% always use MRI. However, 46% use point A only for dose specification to the target. There was a lot of variation in parameters used for dose evaluation of target volume and normal tissues. Compared with the 2007 survey, use of MRI has increased from 2% to 34% (P<.0001) for dose specification to the target. Use of volume-based dose delineation to the target has increased from 14% to 52% (P<.0001). Conclusion: Although use of image-based brachytherapy has increased in the United States since the 2007 survey, there is room for further growth, particularly with the use of MRI. This increase may be in part due to educational initiatives. However, there is still significant heterogeneity in brachytherapy practice in the United States, and future efforts should be geared toward standardizing treatment.« less

Effects of Heparin and ε-Aminocaproic Acid in Dogs on Plasmin- 125I Generation in Response to Urokinase Injections and Venous Injury

PubMed Central

Takeda, Y.; Parkhill, T. R.; Nakabayashi, M.

1972-01-01

The isotopic method described previously for quantification of plasmin- 125I by disc gel electrophoresis was modified by inclusion of euglobulin precipitation to expand its applicability to plasmas containing low radioactivity of plasmin- 125I and plasminogen- 125I. It was found that the euglobulin precipitation method precipitates 72.4±2.1 (sd)% of both plasmin- 125I and plasminogen- 125I. Using this method and plasminogen- 125I as a tracer, studies were first made of the effects of heparin and ε-aminocaproic acid in dogs on plasmin- 125I generation in responese to a single injection of urokinase and to venous injury; second, of the effects of venous occlusion and thrombosis on plasmin- 125I generation; and third, in vitro studies of plasminogen- 125I affinity to fibrin and its activation in blood clots. The venous injury was produced by the damage of venous endothelium by an injection of 90% phenol and the thrombosis by a thrombin injection into an occluded vein. Heparin and ε-aminocaproic acid under the present experimental conditions inhibited about 78 and 100%, respectively of plasmin- 125I generation by the urokinase injection. Similar inhibitory effects of heparin and ε-aminocaproic acid were observed on plasmin- 125I generation in response to venous injury. The venous occlusion caused a small degree of plasmin- 125I generation, but thrombin thrombosis did not seem to stimulate the generation of plasmin- 125I. The in vitro studies showed that plasminogen- 125I does not have a specific affinity to fibrin and is incorporated into blood clots in approximately equal concentrations as those in serum during clotting processes, and that blood clots per se do not stimulate plasmin- 125I generation. These results suggest that injured veins release considerable amounts of vascular plasminogen activators into circulation and that these play an important role in thrombus dissolution in vivo. PMID:4262519

A Dose–Response Analysis of Biochemical Control Outcomes After {sup 125}I Monotherapy for Patients With Favorable-Risk Prostate Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shiraishi, Yutaka, E-mail: shiraishi@rad.med.keio.ac.jp; Department of Radiology, National Hospital Organization Tokyo Medical Center, Tokyo; Yorozu, Atsunori

Purpose: To define the optimal dose for {sup 125}I prostate implants by correlating postimplantation dosimetry findings with biochemical failure and toxicity. Methods and Materials: Between 2003 and 2009, 683 patients with prostate cancer were treated with {sup 125}I prostate brachytherapy without supplemental external beam radiation therapy and were followed up for a median time of 80 months. Implant dose was defined as the D90 (the minimal dose received by 90% of the prostate) on postoperative day 1 and 1 month after implantation. Therefore, 2 dosimetric variables (day 1 D90 and day 30 D90) were analyzed for each patient. We investigated the dosemore » effects on biochemical control and toxicity. Results: The 7-year biochemical failure-free survival (BFFS) rate for the group overall was 96.4% according to the Phoenix definition. A multivariate analysis found day 1 D90 and day 30 D90 to be the most significant factors affecting BFFS. The cutoff points for day 1 D90 and day 30 D90, calculated from ROC curves, were 163 Gy and 175 Gy, respectively. By use of univariate analysis, various dosimetric cutoff points for day 30 D90 were tested. We found that day 30 D90 cutoff points from 130 to 180 Gy appeared to be good for the entire cohort. Greater D90s were associated with an increase in late genitourinary or gastrointestinal toxicity ≥ grade 2, but the increase was not statistically significant. Conclusions: Improvements in BFFS rates were seen with increasing D90 levels. Day 30 D90 doses of 130 to 180 Gy were found to serve as cutoff levels. For low-risk and low-tier intermediate-risk prostate cancer patients, high prostate D90s, even with doses exceeding 180 Gy, achieve better treatment results and are feasible.« less

delta 9-(16 alpha-/sup 125/I)iodo-19-nortestosterone: a gamma-emitting photoaffinity label for the progesterone receptor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lamb, D.J.; Bullock, D.W.; Hoyte, R.M.

1988-05-01

We have synthesized 16 alpha-iodo-4,9-estradien-17 beta-ol-3-one (delta 9-16 alpha-iodo-19-nortestosterone (delta 9-INT)) labeled with 125I (delta 9-(16 alpha-125I)INT) to provide a new gamma-emitting photoaffinity ligand for the progesterone receptor that has many advantages over the currently available (3H)R5020. We have characterized the interaction of delta 9-(16 alpha-125I)INT with the rabbit uterine progesterone receptor and have demonstrated the usefulness of this compound for studies of receptor structure. The binding of 2 nM (3H)progesterone to receptor in rabbit uterine cytosol was specifically competed for by 19-nortestosterone, 16 alpha-iodo-19-nortestosterone, and delta 9-INT. Scatchard analysis demonstrated that delta 9-(16 alpha-125I)INT and (3H)progesterone estimated the samemore » number of binding sites in rabbit uterine cytosol, with a Kd for delta 9-(16 alpha-125I)INT of about 2.7 nM. The binding of delta 9-(16 alpha-125I)INT was inhibited by both progesterone and R5020, whereas testosterone, estradiol, and 5 alpha-dihydrotestosterone were ineffective. In cytosol, delta 9-(16 alpha-125I)INT covalently labeled the same mol wt receptor forms as (3H)R5020. Although the efficiency of cross-linking was similar for (3H)R5020 (3%) and delta 9-(16 alpha-125I)INT (4%), the radioactivity was 10-fold greater due to the higher specific activity of delta 9-(16 alpha-125I)INT and the lack of sample quench. The use of delta 9-(16 alpha-125I)INT greatly increases the sensitivity and efficiency of the photoaffinity labeling technique; it will provide a valuable tool for further studies of the progesterone receptor, allowing the detection of receptor in dilute cytosol after gel electrophoresis under denaturing conditions.« less

Penile brachytherapy: Results for 49 patients

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crook, Juanita M.; Jezioranski, John; Grimard, Laval

2005-06-01

Purpose: To report results for 49 men with squamous cell carcinoma (SCC) of the penis treated with primary penile interstitial brachytherapy at one of two institutions: the Ottawa Regional Cancer Center, Ottawa, and the Princess Margaret Hospital, Toronto, Ontario, Canada. Methods and Materials: From September 1989 to September 2003, 49 men (mean age, 58 years; range, 22-93 years) had brachytherapy for penile SCC. Fifty-one percent of tumors were T1, 33% T2, and 8% T3; 4% were in situ and 4% Tx. Grade was well differentiated in 31%, moderate in 45%, and poor in 2%; grade was unspecified for 20%. Onemore » tumor was verrucous. All tumors in Toronto had pulsed dose rate (PDR) brachytherapy (n = 23), whereas those in Ottawa had either Iridium wire (n 22) or seeds (n = 4). Four patients had a single plane implant with a plastic tube technique, and all others had a volume implant with predrilled acrylic templates and two or three parallel planes of needles (median, six needles). Mean needle spacing was 13.5 mm (range, 10-18 mm), mean dose rate was 65 cGy/h (range, 33-160 cGy/h), and mean duration was 98.8 h (range, 36-188 h). Dose rates for PDR brachytherapy were 50-61.2 cGy/h, with no correction in total dose, which was 60 Gy in all cases. Results: Median follow-up was 33.4 months (range, 4-140 months). At 5 years, actuarial overall survival was 78.3% and cause-specific survival 90.0%. Four men died of penile cancer, and 6 died of other causes with no evidence of recurrence. The cumulative incidence rate for never having experienced any type of failure at 5 years was 64.4% and for local failure was 85.3%. All 5 patients with local failure were successfully salvaged by surgery; 2 other men required penectomy for necrosis. The soft tissue necrosis rate was 16% and the urethral stenosis rate 12%. Of 8 men with regional failure, 5 were salvaged by lymph node dissection with or without external radiation. All 4 men with distant failure died of disease. Of 49 men, 42 had

[125I]-GR231118: a high affinity radioligand to investigate neuropeptide Y Y1 and Y4 receptors

PubMed Central

Dumont, Yvan; Quirion, Rémi

2000-01-01

GR231118 (also known as 1229U91 and GW1229), a purported Y1 antagonist and Y4 agonist was radiolabelled using the chloramine T method. [125I]-GR231118 binding reached equilibrium within 10 min at room temperature and remained stable for at least 4 h. Saturation binding experiments showed that [125I]-GR231118 binds with very high affinity (Kd of 0.09–0.24 nM) in transfected HEK293 cells with the rat Y1 and Y4 receptor cDNA and in rat brain membrane homogenates. No specific binding sites could be detected in HEK293 cells transfected with the rat Y2 or Y5 receptor cDNA demonstrating the absence of significant affinity of GR231118 for these two receptor classes. Competition binding experiments revealed that specific [125I]-GR231118 binding in rat brain homogenates is most similar to that observed in HEK293 cells transfected with the rat Y1, but not rat Y4, receptor cDNA. Autoradiographic studies demonstrated that [125I]-GR231118 binding sites were fully inhibited by the Y1 antagonist BIBO3304 in most areas of the rat brain. Interestingly, high percentage of [125I]-GR231118/BIBO3304-insensitive binding sites were detected in few areas. These [125I]-GR231118/BIBO3304-insensitive binding sites likely represent labelling to the Y4 receptor subtype. In summary, [125I]-GR231118 is a new radiolabelled probe to investigate the Y1 and Y4 receptors; its major advantage being its high affinity. Using highly selective Y1 antagonists such as BIBO3304 or BIBP3226 it is possible to block the binding of [125I]-GR231118 to the Y1 receptor allowing for the characterization and visualization of the purported Y4 subtype. PMID:10694200

Developing A Directional High-Dose Rate (d-HDR) Brachytherapy Source

NASA Astrophysics Data System (ADS)

Heredia, Athena Yvonne

Conventional sources used in brachytherapy provide nearly isotropic or radially symmetric dose distributions. Optimizations of dose distributions have been limited to varied dwell times at specified locations within a given treatment volume, or manipulations in source position for seed implantation techniques. In years past, intensity modulated brachytherapy (IMBT) has been used to reduce the amount of radiation to surrounding sensitive structures in select intracavitary cases by adding space or partial shields. Previous work done by Lin et al., at the University of Wisconsin-Madison, has shown potential improvements in conformality for brachytherapy treatments using a directionally shielded low dose rate (LDR) source for treatments in breast and prostate. Directional brachytherapy sources irradiate approximately half of the radial angles around the source, and adequately shield a quarter of the radial angles on the opposite side, with sharp gradient zones between the treated half and shielded quarter. With internally shielded sources, the radiation can be preferentially emitted in such a way as to reduce toxicities in surrounding critical organs. The objective of this work is to present findings obtained in the development of a new directional high dose rate (d-HDR) source. To this goal, 103Pd (Z = 46) is reintroduced as a potential radionuclide for use in HDR brachytherapy. 103Pd has a low average photon energy (21 keV) and relatively short half -life (17 days), which is why it has historically been used in low dose rate applications and implantation techniques. Pd-103 has a carrier-free specific activity of 75000 Ci/g. Using cyclotron produced 103Pd, near carrier-free specific activities can be achieved, providing suitability for high dose rate applications. The evolution of the d-HDR source using Monte Carlo simulations is presented, along with dosimetric parameters used to fully characterize the source. In addition, a discussion on how to obtain elemental

Dosimetric impact of an air passage on intraluminal brachytherapy for bronchus cancer.

PubMed

Okamoto, Hiroyuki; Wakita, Akihisa; Nakamura, Satoshi; Nishioka, Shie; Aikawa, Ako; Kato, Toru; Abe, Yoshihisa; Kobayashi, Kazuma; Inaba, Koji; Murakami, Naoya; Itami, Jun

2016-11-01

The brachytherapy dose calculations used in treatment planning systems (TPSs) have conventionally been performed assuming homogeneous water. Using measurements and a Monte Carlo simulation, we evaluated the dosimetric impact of an air passage on brachytherapy for bronchus cancer. To obtain the geometrical characteristics of an air passage, we analyzed the anatomical information from CT images of patients who underwent intraluminal brachytherapy using a high-dose-rate 192 Ir source (MicroSelectron V2r®, Nucletron). Using an ionization chamber, we developed a measurement system capable of measuring the peripheral dose with or without an air cavity surrounding the catheter. Air cavities of five different radii (0.3, 0.5, 0.75, 1.25 and 1.5 cm) were modeled by cylindrical tubes surrounding the catheter. A Monte Carlo code (GEANT4) was also used to evaluate the dosimetric impact of the air cavity. Compared with dose calculations in homogeneous water, the measurements and GEANT4 indicated a maximum overdose of 5-8% near the surface of the air cavity (with the maximum radius of 1.5 cm). Conversely, they indicated a minimum overdose of ~1% in the region 3-5 cm from the cavity surface for the smallest radius of 0.3 cm. The dosimetric impact depended on the size and the distance of the air passage, as well as the length of the treatment region. Based on dose calculations in water, the TPS for intraluminal brachytherapy for bronchus cancer had an unexpected overdose of 3-5% for a mean radius of 0.75 cm. This study indicates the need for improvement in dose calculation accuracy with respect to intraluminal brachytherapy for bronchus cancer. © The Author 2016. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology.

Dosimetric impact of an air passage on intraluminal brachytherapy for bronchus cancer

PubMed Central

Okamoto, Hiroyuki; Wakita, Akihisa; Nakamura, Satoshi; Nishioka, Shie; Aikawa, Ako; Kato, Toru; Abe, Yoshihisa; Kobayashi, Kazuma; Inaba, Koji; Murakami, Naoya; Itami, Jun

2016-01-01

The brachytherapy dose calculations used in treatment planning systems (TPSs) have conventionally been performed assuming homogeneous water. Using measurements and a Monte Carlo simulation, we evaluated the dosimetric impact of an air passage on brachytherapy for bronchus cancer. To obtain the geometrical characteristics of an air passage, we analyzed the anatomical information from CT images of patients who underwent intraluminal brachytherapy using a high-dose-rate 192Ir source (MicroSelectron V2r®, Nucletron). Using an ionization chamber, we developed a measurement system capable of measuring the peripheral dose with or without an air cavity surrounding the catheter. Air cavities of five different radii (0.3, 0.5, 0.75, 1.25 and 1.5 cm) were modeled by cylindrical tubes surrounding the catheter. A Monte Carlo code (GEANT4) was also used to evaluate the dosimetric impact of the air cavity. Compared with dose calculations in homogeneous water, the measurements and GEANT4 indicated a maximum overdose of 5–8% near the surface of the air cavity (with the maximum radius of 1.5 cm). Conversely, they indicated a minimum overdose of ~1% in the region 3–5 cm from the cavity surface for the smallest radius of 0.3 cm. The dosimetric impact depended on the size and the distance of the air passage, as well as the length of the treatment region. Based on dose calculations in water, the TPS for intraluminal brachytherapy for bronchus cancer had an unexpected overdose of 3–5% for a mean radius of 0.75 cm. This study indicates the need for improvement in dose calculation accuracy with respect to intraluminal brachytherapy for bronchus cancer. PMID:27605630

The use of nomograms in LDR-HDR prostate brachytherapy.

PubMed

Pujades, Ma Carmen; Camacho, Cristina; Perez-Calatayud, Jose; Richart, José; Gimeno, Jose; Lliso, Françoise; Carmona, Vicente; Ballester, Facundo; Crispín, Vicente; Rodríguez, Silvia; Tormo, Alejandro

2011-09-01

The common use of nomograms in Low Dose Rate (LDR) permanent prostate brachytherapy (BT) allows to estimate the number of seeds required for an implant. Independent dosimetry verification is recommended for each clinical dosimetry in BT. Also, nomograms can be useful for dose calculation quality assurance and they could be adapted to High Dose Rate (HDR). This work sets nomograms for LDR and HDR prostate-BT implants, which are applied to three different institutions that use different implant techniques. Patients treated throughout 2010 till April 2011 were considered for this study. This example was chosen to be the representative of the latest implant techniques and to ensure consistency in the planning. A sufficient number of cases for both BT modalities, prescription dose and different work methodology (depending on the institution) were taken into account. The specific nomograms were built using the correlation between the prostate volume and some characteristic parameters of each BT modality, such as the source Air Kerma Strength, number of implanted seeds in LDR or total radiation time in HDR. For each institution and BT modality, nomograms normalized to the prescribed dose were obtained and fitted to a linear function. The parameters of the adjustment show a good agreement between data and the fitting. It should be noted that for each institution these linear function parameters are different, indicating that each centre should construct its own nomograms. Nomograms for LDR and HDR prostate brachytherapy are simple quality assurance tools, specific for each institution. Nevertheless, their use should be complementary to the necessary independent verification.

Development of a high specific activity radioligand, /sup 125/I-LSD, and its application to the study of serotonin receptors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kadan, M.J.

/sup 125/I-Labeled receptor ligands can be synthesized with specific activities exceeding 2000 Ci/mmol, making them nearly 70-fold more sensitive in receptor site assays than (mono) tritiated ligands. We have synthesized and characterized /sup 125/I-lysergic acid diethylamide (/sup 125/I-LSD), the first radioiodinated ligand for serotonin receptor studies. The introduction of /sup 125/I at the 2 position of LSD increased both the affinity and selectivity of this compound for serotonin 5-HT/sub 2/ receptors in rat cortex. The high specific activity of /sup 125/I-LSD and its high ratio of specific to nonspecific binding make this ligand especially useful for autoradiographic studies of serotoninmore » receptor distribution. We have found that /sup 125/I-LSD binds with high affinity to a class of serotonin receptors in the CNS of the marine mollusk Aplysia californica.« less

SU-F-BRA-03: Integrating Novel Electromagnetic Tracking Hollow Needle Assistance in Permanent Implant Brachytherapy Procedures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Racine, E; Hautvast, G; Binnekamp, D

Purpose: To report on the results of a complete permanent implant brachytherapy procedure assisted by an electromagnetic (EM) hollow needle possessing both 3D tracking and seed drop detection abilities. Methods: End-to-end in-phantom EM-assisted LDR procedures were conducted. The novel system consisted of an EM tracking apparatus (NDI Aurora V2, Planar Field Generator), a 3D US scanner (Philips CX50), a hollow needle prototype allowing 3D tracking and seed drop detection and a specially designed treatment planning software (Philips Healthcare). A tungsten-doped 30 cc spherical agarose prostate immersed in gelatin was used for the treatment. A cylindrical shape of 0.8 cc wasmore » carved along its diameter to mimic the urethra. An initial plan of 26 needles and 47 seeds was established with the system. The plan was delivered with the EM-tracked hollow needle, and individual seed drop locations were recorded on the fly. The phantom was subsequently imaged with a CT scanner from which seed positions and contour definitions were obtained. The DVHs were then independently recomputed and compared with those produced by the planning system, both before and after the treatment. Results: Of the 47 seeds, 45 (96%) were detected by the EM technology embedded in the hollow needle design. The executed plan (from CT analysis) differed from the initial plan by 2%, 14% and 8% respectively in terms of V100, D90 and V150 for the prostate, and by 8%, 7% and 10% respectively in terms of D5, V100 and V120 for the urethra. Conclusion: The average DVH deviations between initial and executed plans were within a 5% tolerance imposed for this proof-of-concept assessment. This relatively good concordance demonstrates the feasibility and potential benefits of combining EM tracking and seed drop detection for real-time dosimetry validation and assistance in permanent implant brachytherapy procedures. This project has been entirely funded by Philips Healthcare.« less

DNA-incorporated 125I induces more than one double-strand break per decay in mammalian cells.

PubMed

Elmroth, Kecke; Stenerlöw, Bo

2005-04-01

The Auger-electron emitter 125I releases cascades of 20 electrons per decay that deposit a great amount of local energy, and for DNA-incorporated 125I, approximately one DNA double-strand break (DSB) is produced close to the decay site. To investigate the potential of 125I to induce additional DSBs within adjacent chromatin structures in mammalian cells, we applied DNA fragment-size analysis based on pulsed-field gel electrophoresis (PFGE) of hamster V79-379A cells exposed to DNA-incorporated 125IdU. After accumulation of decays at -70 degrees C in the presence of 10% DMSO, there was a non-random distribution of DNA fragments with an excess of fragments <0.5 Mbp and the measured yield was 1.6 DSBs/decay. However, since these experiments were performed under high scavenging conditions (DMSO) that reduce indirect effects, the yield in cells exposed to 125IdU under physiological conditions would most likely be even higher. In contrast, using a conventional low-resolution assay without measurement of smaller DNA fragments, the yield was close to one DSB/decay. We conclude that a large fraction of the DSBs induced by DNA-incorporated 125I are nonrandomly distributed and that significantly more than one DSB/decay is induced in an intact cell. Thus, in addition to DSBs produced close to the decay site, DSBs may also be induced within neighboring chromatin fibers, releasing smaller DNA fragments that are not detected by conventional DSB assays.