Characterization of Geiger-Müller radiation detectors response at the University of Costa Rica's Cyclotron Facilities / Caracterización de la respuesta de detectores de radiación Geiger-Müller en el Ciclotrón de la Universidad de Costa Rica

To ensure a reliable verification of a radiation detector, the right parameters for this response verification must be determined and a specific characterization on the detectors of interest must be performed. These were the main pillars of this study, where four Geiger-Müller at the University of Costa Rica's Cyclotron Facilities' main laboratories were studied and characterized using a 137Cs source. First, a verification of the inverse-square law was performed to corroborate the correct measurement by the detectors as the distance from a 137Cs source to the detectors was varied using a new design for a positioner support to ensure repeatability. This verification yielded a potential fit curve with and equation D=670635 x-1.961 (error percentage of 1.95%) and an R2 value of 0.9836. Then, using combinations of copper plates of widths 1.0 mm and 2.0 mm as attenuators between the source and the detectors, the mass attenuation coefficient for copper was obtained only as a reference value for future calibrations of the detectors. The result for this value was 0.040 cm2 /g. The results obtained in this study and the method developed to achieve these results will serve as a base for calibrations of the detectors at these facilities, which will ensure the safety of the patients and personnel in this building.

Para asegurar respuesta correcta de un detector de radiación, se deben determinar los parámetros correctos para esta verificación y debe realizarse una caracterización específica de los detectores de interés. Estos fueron los pilares principales de este estudio, donde se estudiaron y caracterizaron 4 detectores Geiger-Müller en los laboratorios principales del Ciclotrón de la Universidad de Costa Rica utilizando una fuente radiactiva de 137Cs. Primero, se realizó una verificación de la ley del inverso-cuadrado para corroborar la medición correcta de los detectores según se varía la distancia entre la fuente de 137Cs al detector utilizando un diseño nuevo de un soporte posicionador para la fuente que asegura la repetibilidad entre experimentos. Esta verificación resultó en una curva de ajuste potencial de ecuación D=670635x-1,961 (porcentaje de error de 1,95%) y un valor de R2 de 0,9836. Luego, utilizando combinaciones de placas de cobre de espesores 1,0 mm y 2,0 mm como atenuadores entre la fuente y los detectores, se obtuvo el coeficiente de atenuación másico para el cobre como un valor de referencia para futuras calibraciones de los detectores. Este resultado fue de 0,040 cm2/g. Los resultados obtenidos en esta investigación y el método desarrollado para lograr estos resultados servirán como una base para una futura confirmación metrológica calibraciones de los detectores en estos laboratorios, lo cual colaborará con la seguridad y protección radiológica de pacientes y trabajadores en este edificio.

Analysis of Performance of the MINItrace Cyclotron before and after Upgrade / 中国医疗器械杂志

OBJECTIVE@#To compare the performance of the GE cyclotron MINItrace system before and after the upgrade.@*METHODS@#The upgrade of the MINItrace system included replacing the silver target with the Nb syetem and adopting the latest RF control and management system and lastest ion source system.The failrue rate and production efficiency were retrospectively analyzed before and after the upgrade.@*RESULTS@#After the upgrade, the cyclotron failure rate decreased by 86.2%, the average capacity increased by 45%.@*CONCLUSIONS@#After the upgrade of MINItrace cyclotron, the failure rate is sharply reduced, and the production efficiency is grately improved.

The Maintenance and Common Troubleshooting of GE MINItrace Qilin Medical Cyclotron / 中国医疗器械杂志

This study analyzes the maintenance and common faults of GE MINItrace Qilin medical cyclotron, and studies three kinds of the machine's faults.

Efforts in the Formation and Development of Nuclear Medicine in Vietnam / 대한핵의학회잡지

The foundations of nuclear medicine in Vietnam were established from 1970. Until now, after 48 years of development, in Vietnam, we have some basic equipment including 31 SPECT, 4 SPECT/CT machines, 11 PET/CT scanners, five cyclotrons, and one nuclear reactor.Many nuclearmedicine techniques in diagnosis and treatment have been routinely performed at provincial and central level health facilities such as tumor scintigraphy, thyroid scintigraphy, bone scintigraphy, kidney scintigraphy, cardiac scintigraphy, and radio-isotope therapy with I-131 and P-32. Selective internal radiation therapy with Y-90 microsphere and I-125 radioactive seed implantation has been also successfully applied in some big hospitals. However, there are still many difficulties for Vietnam as the lack of new widely used radioisotopes such as Ga-67, Cu-64, Samarium-153, and Lutetium-177 and the lack of nuclear medicine specialists. In the future, we are putting our efforts on the applications of new isotopes in diagnosis and treatment of cancers (theranostic) like Ga-68-DOTATATE, Lutetium-177-DOTATATE, Ga-68-PSMA, and Lutetium-177-PSMA, equipping modern nuclear medicine diagnostic tools, strengthening the human resources training in nuclear medicine. At the same time, we are trying our best to strengthen the cooperation with international nuclear medicine societies in over the world.

Theranostics in Bangladesh: Current Status, Challenges, and Future Perspective / 대한핵의학회잡지

BACKGROUND AND CURRENT STATUS OF THERANOSTICS: Therapeutic nuclear medicine (NM) in Bangladesh began in the early 1980s with the application of radioactive iodine for treatment of thyroid cancer and primary hyperthyroidism. Since then, NM practice has remarkably developed in the country with the advancement of instrumentation, radiopharmacy, and information technology. The government took the initiative to establish four PET-CTcenters at different NMcenters, including one at the National Institute of Nuclear Medicine and Allied Sciences (NINMAS). A further development is the installation of a cyclotron center (18-MeV cyclotron) at NINMAS by the government's fund. Currently, NM is providing good health services to oncology patients throughout the country. More than 20 NM centers are functioning in different parts of the country, and therapeutic NM has an important place. However, conventional radioactive iodine still remains the major theranostic application.CHALLENGES AND FUTURE PERSPECTIVE: The expansion and development of therapeutic NM for other cancers have been limited due to a number of challenging factors. A brief overview of the history and current status ofNMin Bangladesh is presented here with an examination of factors that pose as obstacles to the introduction and development of new therapeutic technologies. Finally, future perspectives are discussed with ways to mitigate existing problems and challenges.

Preparation, quality control and thyroid molecule imaging of solid-target based radionuclide ioine-124 / 北京大学学报(医学版)

OBJECTIVE@#To provide useful information for the further production and application of this novel radio-nuclide for potential clinical application.@*METHODS@#124Te (p,n) 124I nuclide reaction was used for the 124I production. Firstly, the target material, 124TeO2 (200 mg) and Al2O3 (30 mg) mixture, were compressed into the round platinum based solid target by tablet device. HM-20 medical cyclotron was applied to irradiate the solid target slice for 6-10 h with helium and water cooling. Then, the radiated solid target was placed for 12 h (overnight) to decay the radioactive impurity; finally, 124I was be purified by dry distillation using 1 mL/min nitrogen for about 6 hours and radiochemical separation methods. Micro-PET imaging studies were performed to investigate the metabolism properties and thyroid imaging ability of 124I.After 740 kBq 124I was injected intravenously into the tail vein of the normal mice, the animals were imaged with micro-PET and infused with CT. The micro-PET/CT infusion imaging revealed actual state 124I's metabolism in the mice.@*RESULTS@#It was been successfully applied for 200 mg 124TeO2 plating by the tablet device on the surface of platinum. It showed smooth, dense surface and without obviously pits and cracks. The enriched 124Te target was irradiated for 6 to 10 hours at about 12.0 MeV with 20 μA current on HM-20 cyclotron. Then 370-1 110 MBq 124I could be produced on the solid target after irradiation and 370-740 MBq high specific activity could be collected afterdry distillation separation and radio-chemical purification.124I product was finally dissolved in 0.01 mol/L NaOH for the future distribution. The gamma spectrum of the produced 124I-solution showed that radionuclide purity was over 80.0%. The micro-PET imaging of 124I in the normal mice exhibited the thyroid and stomach accumulations and kidney metabolism, the bladder could also be clearly visible, which was in accordance with what was previously reported. To the best of our knowledge, it was the first production of 124I report in China.@*CONCLUSION@#In this study, the preparation of 124TeO2 solid target was successfully carried out by using the tablet device. After irradiation of the 124TeO2 solid target and radio-chemical purification, we successfully produced 370-740 MBq high specific activity 124I by a cyclotron for biomedical application, and micro-PET imaging of 124I in normal mice exhibited the thyroid accumulations. Also, slight uptake in stomach were also monitored with almost nonuptake in other organs in the micro-PET imaging. The production of 124I is expected to provide a new solid target radionuclide for the scientific research and potential clinical application of our country.

The first private-hospital based proton therapy center in Korea; status of the Proton Therapy Center at Samsung Medical Center

PURPOSE: The purpose of this report is to describe the proton therapy system at Samsung Medical Center (SMC-PTS) including the proton beam generator, irradiation system, patient positioning system, patient position verification system, respiratory gating system, and operating and safety control system, and review the current status of the SMC-PTS. MATERIALS AND METHODS: The SMC-PTS has a cyclotron (230 MeV) and two treatment rooms: one treatment room is equipped with a multi-purpose nozzle and the other treatment room is equipped with a dedicated pencil beam scanning nozzle. The proton beam generator including the cyclotron and the energy selection system can lower the energy of protons down to 70 MeV from the maximum 230 MeV. RESULTS: The multi-purpose nozzle can deliver both wobbling proton beam and active scanning proton beam, and a multi-leaf collimator has been installed in the downstream of the nozzle. The dedicated scanning nozzle can deliver active scanning proton beam with a helium gas filled pipe minimizing unnecessary interactions with the air in the beam path. The equipment was provided by Sumitomo Heavy Industries Ltd., RayStation from RaySearch Laboratories AB is the selected treatment planning system, and data management will be handled by the MOSAIQ system from Elekta AB. CONCLUSION: The SMC-PTS located in Seoul, Korea, is scheduled to begin treating cancer patients in 2015.

Targetry for cyclotron production of no carrier-added cadmium- 109 from natAg[p, n] 109 Cd reaction

Solid targets that consist of powder and electrodeposited targets are used commonly to produce radionuclides by accelerators. Since silver is easily electrodeposited in cyanide baths and has a very excellent thermal conductivity, the electrodeposited target is preferable to produce [109] Cd. To avoid cracking of peeling of the target during bombardment, it should have a level surface and a good adhesion to substrate. Hence, suitable targetry has extraordinary importance for the interested radionuclide production. Excitation function of cadmium-109 via [nat] Ag [p,n][109] Cd reaction was investigated by using ALICE-91 code. The required thickness of the silver deposit was calculated by SRIM code. Theoretical yield was calculated by means of Simpson numerical integral method. Silver was electrodeposited on copper backing by the cyanide bath. The prepared targets were examined with morphology and thermal shock tests. The most favorable beam energy was determined as 15 MeV. The desired thickness was determined to be up to 48 micro m; the theoretical calculated yield was 2.69 micro Ci/ micro A.h. Scanning electron microscope [SEM] potomicrographs and thermal shock tests represented excellent quality of the electrodeposited target. The present study suggested a good potentiality of cadmium-109 production by induced proton on electrodeposited silver targets

Preparation and biodistribution of [67Ga]-labeledoxytocin for SPECT purposes

Oxytocin [OT] is a paracrine hormone with various biological activities and many sex organs in both sexes, as well as many tumor cells have shown to have related receptors. In this study the development of a receptor imaging tracer for possible tumor imaging has been described. OT was successively labeled with [67Ga]-gallium chloride after conjugation with freshly prepared cyclic DTPA-dianhydride. The best results of the conjugation were obtained by the addition of 1 ml of a OT pharmaceutical solution [2 mg/ml, in phosphate buffer, pH=8] to a glass tube pre-coated with DTPA-dianhydride [0.02 mg] at 25°C with continuous mild stirring for 30 min. Radiochemical purity [RCP] of the labeled compound was determined, using RTLC and ITLC followed by stability tests and animal biodistribution studies. Radiolabeling took about 60 minutes with a RCP higher than 98% at optimized conditions [specific activity = 1000 Ci/mM, labeling efficiency 80%]. The stability of the tracer at room temperature was significant, up to an hour. Preliminary in vivo studies in normal female rat model showed ovary/blood and ovary/muscle ratio uptake of the tracer in 60 minutes to be 4.53 and 9.18, respectively. The result was consistent with the reported OT receptor distribution in normal female mammals. The radiolabeled oxytocin, prepared in this study, was a possible fast acting tracer for OT receptor imaging; studies however, more studies are required to determine the best imaging conditions especially in larger mammal animals

A Study of Radiation Exposure in Proton Therapy Facility / 의학물리

Proton therapy facility, which is recently installed at National Cancer Center in Korea, generally produces a large amount of radiation near cyclotron due to the secondary particles and radioisotopes caused by collision between proton and nearby materials during the acceleration. Although the level of radiation by radioisotope decreases in length of time, radiation exposure problem still exists since workers are easily exposed by a low level of radiation for a long time due to their job assignment for maintenance or repair of the proton facility. In this paper, the working environment near cyclotron, where the highest radiation exposure is expected, was studied by measuring the degree of radiation and its duration for an appropriate level of protective action guide. To do this, we measured the radiation change in the graphite based energy degrader, the efficiency of transmitted beam and relative activation degree of the transmission beam line. The results showed that while the level of radiation exposure around cyclotron and beam line during the operation is much higher than the other radiation therapy facilities, the radiation exposure rate per year is under the limit recommended by the law showing 1~3 mSv/year.

Alpha-emitting Radioisotopes Production for Radioimmunotherapy / 핵의학분자영상

This review discusses the production of alpha-particle-emitting radionuclides in radioimmunotherapy. Radioimmunotherapy labeled with alpha-particle is expected to be very useful for the treatment of monocellular cancer (e.g. leukemia) and micrometastasis at an early stage, residual tumor remained in tissues after chemotherapy and tumor resection, due to the high linear energy transfer (LET) and the short path length in biological tissue of alpha particle. Despite of the expected effectiveness of alpha-particle in radioimmunotherapy, its clinical research has not been activated by the several reasons, shortage of a suitable a-particle development and a reliable radionuclide production and supply system, appropriate antibody and chelator development. Among them, the establishment of radionuclide development and supply system is a key factor to make an alpha-immunotherapy more popular in clinical trial. Alpha-emitter can be produced by several methods, natural radionuclides, reactor irradiation, cyclotron irradiation, generator system and elution. Due to the sharply increasing demand of 213Bi, which is a most promising radionuclide in radioimmunotherapy and now has been produced with reactor, the cyclotron production system should be developed urgently to meet the demand.

Production of Ga-66 from natural zinc

In this study, production of Gallium-66 by irradiation of natural zinc target with 15 MeV protons was verified.Gallium-66 is an intermediate-lived radioisotope that has potential for positron emission tomography (PET), along study of the biological processes with intermediate to slow target tissue uptake. 66Ga [t1/2 = 9.49 h; ß+ (56.5 percent), EC(43.5 percent)] can be used in a large number of labeled proteins, peptides, and small molecules. We have produced 66Ga by irradiation of natural Zinc with 15 MeV proton beam, using the cyclotron -30Cyclon- at nuclear research center for agriculture and medicine. A 400µm Zinc target with copper backing substrate was irradiated for 1.5 hours with total integrated current 250µAh. Gallium has been purified from irradiated targets by passing through the cation exchange column and diisopropyl ether extraction. The concentration of zinc and copper in 0.1 and 0.5 ppm were respectively measured by polarography. In order to detect impurities, gallium radioisotopes were detected by a Canberra HPGe gamma spectrometer. The production yield at EOB was 7mCi/µAh with total activity of 1.75 Ci for Gallium-66. The ratio of activity at 9 hours after the EOB for 66Ga(t 1/2=9.5h), 68Ga(t1/2=1.1h) and 67Ga(t1/2=78h) was 98.63 percent, 1.12 percent and 0.25 percent respectively. The amount of 64Ga(t1/2=0.04h), and 70Ga(t1/2=0.35h) was not detectable. Due to using natural zinc, this method could be considered as an inexpensive method for laboratories studies. The production process comparing the irradiation of natural copper has no impurity such as copper-61, 64 and 67. The purification including cation-exchange and ether extraction afforded high yield beside negligible concentrations of copper and stable zinc as chemical impurity.

Evaluation of Biological Characteristics of Neutron Beam Generated from MC50 Cyclotron / 대한방사선종양학회지

PURPOSE: To evaluate biological characteristics of neutron beam generated by MC50 cyclotron located in the Korea Institute of Radiological and Medical Sciences (KIRAMS). MATERIALS AND METHODS: The neutron beams generated with 15 mm Beryllium target hit by 35 MeV proton beam was used and dosimetry data was measured before in-vitro study. We irradiated 0, 1, 2, 3, 4 and 5 Gy of neutron beam to EMT-6 cell line and surviving fraction (SF) was measured. The SF curve was also examined at the same dose when applying lead shielding to avoid gamma ray component. In the X-ray experiment, SF curve was obtained after irradiation of 0, 2, 5, 10, and 15 Gy. RESULTS: The neutron beams have 84% of neutron and 16% of gamma component at the depth of 2 cm with the field size of 26 x 26 cm2, beam current 20 micro A, and dose rate of 9.25 cGy/min. The SF curve from X-ray, when fitted to linear-quadratic (LQ) model, had 0.611 as alpha/beta ratio (alpha=0.0204, beta=0.0334, R2=0.999, respectively). The SF curve from neutron beam had shoulders at low dose area and fitted well to LQ model with the value of R2 exceeding 0.99 in all experiments. The mean value of alpha and beta were -0.315 (range, -0.254 ~ -0.360) and 0.247 (0.220~0.262), respectively. The addition of lead shielding resulted in no straightening of SF curve and shoulders in low dose area still existed. The RBE of neutron beam was in range of 2.07~2.19 with SF=0.1 and 2.21~2.35 with SF=0.01, respectively. CONCLUSION: The neutron beam from MC50 cyclotron has significant amount of gamma component and this may have contributed to form the shoulder of survival curve. The RBE of neutron beam generated by MC50 was about 2.2.

Recent Status of Commercial PET Cyclotron and KOTRON-13 / 대한핵의학회잡지

This paper is described on the development of KOTRON-13 and recent status of PET cyclotron by commercial cyclotron companies. KIRAMS has developed medical cyclotron which is KIRAMS-13. Samyoung Unitech produces KOTRON-13 with transfered technology by KIRAMS. As a part of Regional Cyclotron Installation Project, KOTRON-13 cyclotrons and [18F]FDG production modules are being installed at regional cyclotron centers in Korea. The medical concern with radiation technology has been growing for the last several years. Early cancer diagnosis through the cyclotron and PET-CT have been brought to public attention by commercial cyclotron models in the world. The new commercial cyclotron models are introduced compact low energy cyclotrons developed by CTI, GE, Sumitomo in recent. It produces different short-lived radioisotopes, such as [18F], [11C], [13N] and [15O]. For the better reliability acceleration particle is proton only. The characteristics of new model cyclotrons are changed to lower energy corresponding to less 13 MeV. New models have self-shielding and low power consumption. Design criteria for the different types of commercial cyclotrons are described with reference to hospital demands.

Esofagectomia para duplo carcinoma epidermóide invasivo do esôfago, quatro anos após tratamento de carcinoma da base da lingua. Relato de caso / Esophagectomy for double invasive squamous cell carcinoma of the esophagus, four years after treatment of base of the tongue carcinoma. Case report

O artigo relata o tratamento de duplo carcinoma epidermóide subcrônico e invasivo do esôfago em paciete do sexo masculino de 48 anos de idade. O paciente apresentava antecedente de alcoolismo e tabagismo e havia sido tratado previamente para carcinoma epidermóide de base de língua. O intervalo entre o diagnóstico do tumor de base de língua e o tratamento dos dois tumores esofágicos foi de quatro anos e seis meses. O tratamento neo-adjuvante para os cânceres esofágicos foi constituído de quimioterapia, com esquema de 5-fluorouracil associado à cisplatina e radioterapia com dose total de 4.550cGY. Foi então submetido à esofagectomia com linfadenectomia e reconstrução do trânsito digestivo com tubo gástrico. A identificação das duas tumorações só foi possível no intra-operatório, devido ao tumor proximal obstruir a luz esofágica, impossibilitando a passagem do endoscópio. Exames pré-operatórios, como o esofagograma e a tomografia compudadorizada de tórax, detectaram somente um tumor do esôfago. A avaliação histopatológica constatou que as duas tumorações invadiam além da camada muscular esofágica, caracterizando um caso ainda não descrito na literatura de língua inglesa. Enfatiza-se a necessidade de acompanhamento dos pacientes com carcinoma de cabeça e pescoço, realizando endoscopia digestiva alta para pesquisa de possível segundo tumor primário esofágico

Aplicaciones clínicas del PET / Positron emission tomography imaging, PET, in clinical practice

Functional imaging using PET (positron emission tomography) has a great impact on current medical practice. It allows to explore, in a very precise way, different processes such as tissue flow and metabolism. Fluor-deoxyglucose labeled with F18 fluorine represents glucose metabolism. Among its main applications are detection, staging, follow up and recurrence assessment of malignant tumors; myocardial viability detection in patients with myocardial infarction or ischemic cardiomyopathy, and evaluation of hyperactive epileptogenic foci in brain. The basis and clinical applications of PET tomography are reviewed especially oriented to its cost benefit relationship, change in patient management and diagnostic value of the most accepted oncological indications. Important economic resources may be saved with PET in this field, considering appropriate staging and recurrence detection, avoiding expensive therapeutic approaches in advanced disease

Dosimetry of the Low Fluence Fast Neutron Beams for Boron Neutron Capture Therapy / 대한방사선종양학회지

PURPOSE: For the research of Boron Neutron Capture Therapy (BNCT), fast neutrons generated from the MC-50 cyclotron with maximum energy of 34.4 MeV in Korea Cancer Center Hospital were moderated by 70 cm paraffin and then the dose characteristics were investigated. Using these results, we hope to establish the protocol about dose measurement of epi-thermal neutron, to make a basis of dose characteristic of epi-thermal neutron emitted from nuclear reactor, and to find feasibility about accelerator-based BNCT. METHOD AND MATERIALS: For measuring the absorbed dose and dose distribution of fast neutron beams, we used Unidos 10005 (PTW, Germany) electrometer and IC-17 (Far West, USA), IC-18, EIC-1 ion chambers manufactured by A-150 plastic and used IC-17M ion chamber manufactured by magnesium for gamma dose. There chambers were flushed with tissue equivalent gas and argon gas and then the flow rate was 5 cc per minute. Using Monte Carlo N-Particle (MCNP) code, transport program in mixed field with neutron, photon, electron, two dimensional dose and energy fluence distribution was calculated and there results were compared with measured results. RESULTS: The absorbed dose of fast neutron beams was 6.47x10-3 cGy per 1 MU at the 4 cm depth of the water phantom, which is assumed to be effective depth for BNCT. The magnitude of gamma contamination intermingled with fast neutron beams was 65.2+/-0.9% at the same depth. In the dose distribution according to the depth of water, the neutron dose decreased linearly and the gamma dose decreased exponentially as the depth was deepened. The factor expressed energy level, D20/D10, of the total dose was 0.718. CONCLUSION: Through the direct measurement using the two ion chambers, which is made different wall materials, and computer calculation of isodose distribution using MCNP simulation method, we have found the dose characteristics of low fluence fast neutron beams. If the power supply and the target material, which generate high voltage and current, will be developed and gamma contamination was reduced by lead or bismuth, we think, it may be possible to accelerator-based BNCT.