Technetium Isotopes Research Articles

Разработка комплекса масс-спектрометрических с индуктивно связанной плазмой методик определения содержания изотопа технеций-99 в урановых материалах

The methods for the quantitative determination of technetium isotope ( 99 Tc) in uranium materials based on inductively coupled plasma mass-spectrometry are described. The results of the investigation of uranium matrix effect on the analytical signal of 99 Tc for two mass-spectrometer models are presented. Different approaches for the quantification of 99 Tc in uranium materials are investigated including direct analysis and analysis with preliminary uranium separation. The methods for the quantification of 99 Tc consisting of chromatographic separation of uranium and 99 Tc using UTEVA and TEVA resins with consequent ICP-MS detection were developed. The detection limits of the developed methods are within the range of 0.0006 to 0.02 ng/g U. The choice of optimum conditions for quantitative determination of 99 Tc by direct ICP-MS analysis allowed avoiding «tough» ICP-MS operating conditions which consist in high forward power equal to 1600 W. The developed methods require much less time and effort compared to radiometry methods. The introduction of the developed methods allow improving the existing standards for the quality control of the uranium materials in nuclear industry. Keywords: Inductively coupled plasma mass-spectrometry, technetium isotope, uranium fluorides, uranium oxides, chromatographic separation (Russian) DOI: http://dx.doi.org/10.15826/analitika.2013.17.4.005 S.L. Ivanov 1 , N.V. Kuzmina 1 , A.Yu. Leykin 2 , A.V. Prosviryakova 1 , A.V. Saprygin 1,3 1 Open Joint Stock Company «Ural Electochemical Integrated Plant (JSC «UEIP») , Novouralsk, Russian Federation 2 Moscow representative office INTERTECH Corporation , Moscow, Russian Federation 3 FSAEI HPE «Ural Federal University named after the first President of Russia B.N. Yeltsin» , Ekaterinburg, Russian Federation

Application of Different Nuclides in Retrospective Dosimetry

Abstract The activities of nuclides produced via the neutron irradiation of reactor pressure vessel (RPV) steel are used to validate respective fluence calculations. Niobium, nickel, and technetium isotopes from RPV trepans of the decommissioned NPP Greifswald (VVER-440) have been analyzed. The activities were determined by TRAMO (Monte-Carlo) fluence calculations, newly applying 640 neutron-energy groups and ENDF/B7 data. Relative to earlier results, fluences up to 20 % higher have been computed, leading to somewhat better agreement between measurement and calculation, particularly in the case of Tc-99.

Determination of technetium-99 in environmental samples: A review

Due to the lack of a stable technetium isotope, and the high mobility and long half-life, 99Tc is considered to be one of the most important radionuclides in safety assessment of environmental radioactivity as well as nuclear waste management. 99Tc is also an important tracer for oceanographic research due to the high technetium solubility in seawater as TcO 4 −. A number of analytical methods, using chemical separation combined with radiometric and mass spectrometric measurement techniques, have been developed over the past decades for determination of 99Tc in different environmental samples. This article summarizes and compares recently reported chemical separation procedures and measurement methods for determination of 99Tc. Due to the extremely low concentration of 99Tc in environmental samples, the sample preparation, pre-concentration, chemical separation and purification for removal of the interferences for detection of 99Tc are the most important issues governing the accurate determination of 99Tc. These aspects are discussed in detail in this article. Meanwhile, the different measurement techniques for 99Tc are also compared with respect to advantages and drawbacks. Novel automated analytical methods for rapid determination of 99Tc using solid extraction or ion exchange chromatography for separation of 99Tc, employing flow injection or sequential injection approaches are also discussed.

Are pre-operative localization studies useful in parathyroid surgery?

Introduction: Ectopic parathyroid tissue is common and makes surgical localization difficult. Accurate preoperative localization avoids the need for bilateral neck exploration and repeats surgical intervention reducing morbidity. We evaluated the use of ultrasound and technetium isotope labeled sestamibi (99Tc-sestamibi) scanning for preoperative localization of parathyroid adenoma and hyperplasia.

MO‐F‐110‐08: Yields and Dosimetry Estimates for Radioisotopes Produced in Proton‐Induced Reactions on Enriched Molybdenum Targets

Purpose: To investigate radiation dosimetry for 99mTc produced by medical cyclotrons, based on theoretical reaction cross‐sections and yields. Several other technetium isotopes produced in a cyclotron are chemically inseparable from 99mTc. This could increase patient absorbed dose. We compared the resulting doses to those from 99mTc produced by conventional 99Mo/99mTc generators. Methods: We simulated natural and enriched molybdenum thick targets irradiated by 10–30MeV protons. All reaction channels leading to any given reaction product were considered in final yields. The cross‐section calculations were performed using the EMPIRE code. A computer graphical user interface for automatic calculation of isotope yields and activities was created. The pertechnetate, phosphonate as well as MIBI radiation absorbed doses were calculated by OLINDA/EXM 1.1 using the adult male reference. Generator produced 99mTc was assumed to have 100% radionuclide purity. Results: The thick target yields for 99mTc, 99gTc and other isotopes were determined for 16‐ 10MeV, 19‐10MeV and 24‐10MeV energy protons. The difference of radiation doses between pure‐Tc (reactor produced) and mixture‐Tc (cyclotron produced) in main organs were estimated. In highly enriched targets (99.5% 100Mo), the mixture‐Tc doses are about 0.5% larger than the pure‐Tc doses. These differences decreased in the first few hours from the end of beam (EOB) and then increased to 1 % after 24 hours from EOB. In targets with lower enrichment (97.4% 100Mo), the 0–8 hours after EOB doses from the mixture‐Tc isotopes exceeded the pure‐99mTc dose by ∼1% or less. For radiopharmaceuticals injected in patients 24 hours after EOB, this difference increased to 2–5%. Conclusion: Other radioisotopes, which will be produced in the cyclotron together with 99mTc must be considered for their potential to increase patient dose exposure. The differences between the radiation absorbed doses from technetium produced by cyclotrons and nuclear reactors are minimal at EOB, and increase slightly after 24 hours.

Ovarian Sentinel Node: Is It Feasible?

To examine whether the intraoperative combined injection technique is feasible in locating the sentinel node(s) of the ovary. In 16 patients with high-risk uterine cancer and normal postmenopausal ovaries, technetium isotope and blue dye were injected in the right or left ovary during laparotomy, respectively. During the operation, the pelvic and para-aortic lymphatic areas were searched, and the number, method of detection, and location(s) of the hot and/or blue node(s) were recorded. One to 3 sentinel nodes per patient were identified in all but 1 patient (15 of 16, 94%). The sentinel nodes (n = 30) were all located in the para-aortic area. The sentinel nodes of the left ovary were mainly (9 of 14, 64%) located above the inferior mesenteric artery level, as the most sentinel nodes of the right ovary (15 of 16, 94%) were found below the inferior mesenteric artery level (P = 0.001). There were no contralateral or bilateral sentinel nodes. The combined intraoperative injection technique with radioisotope and blue dye is fast enough to identify the ovarian sentinel node(s). The stained nodes were consistently located on a certain lymphatic area. The sentinel node concept for the early ovarian cancer deserves more attention.

Myocardial perfusion imaging in the acute care setting: Does it still have a role?

Patients with possible acute coronary syndrome (ACS) are a common Emergency Department (ED) problem, accounting for approximately 10% of all ED visits. Initial risk stratification hinges on the initial ECG, clinical presentation, and a set of cardiac biomarkers that includes troponin. In patients who are hemodynamically stable, the presence of ischemic ECG changes, either elevation or depression, identifies a highrisk group who require admission and early aggressive care with anti-platelet and anti-thrombotic treatment, with the addition of early reperfusion with those who have ST elevation. In the absence of ischemic ECG changes, patients with a history of coronary disease represent an intermittent risk group. The group of patients who remain, who have a non-ischemic ECG and no history of coronary disease, make up the majority of all ED chest pain patients. Although risk of an ACS is relatively low, it is not negligible. Many of the risk stratification protocols and strategies that have been developed are targeted to accurately identify those few high-risk patients in this group. To accelerate the evaluation process, numerous studies have incorporated various types of imaging into chest pain evaluation protocols. Imaging has various potential advantages when applied to this population. By accurately identifying high-risk patients, initiation of appropriate pharmacotherapy and admission is accelerated. In low-risk patients, the frequency of unnecessary admissions is reduced. By accurately differentiating between highand low-risk patients, the probability of inappropriate disposition is decreased. As a result, costs should be reduced through increased overall efficiency. Utilization of acute imaging for identifying ED patients who have ACS is not a new concept. In the 1970s, Wackers et al used thallium-201 imaging to evaluate 203 patients who presented with presumed ACS. All patients who had myocardial infarction (MI) had abnormal MPI, whereas the majority of those who had atypical chest pain or stable angina had normal MPI, with a minority having equivocal MPI; none had rest MPI interpreted as abnormal. Despite this and other promising studies, the use of acute thallium-201 MPI for evaluating chest pain patients was not adapted widely for various reasons. First, acute imaging with thallium-201 is logistically difficult. Thallium-201 begins to redistribute shortly after myocardial uptake; therefore, imaging must be performed shortly after injection to obtain images reflecting the acute presentation. The isotope characteristics of thallium-201 in combination with the lower sensitivity of planar imaging have limited image quality. In the 1990s, the development of the Tc isotopes, sestamibi, and tetrofosmin led to a renewed interest in using imaging for acute evaluation of chest pain patients. Technetium isotopes have the advantage in that they do not redistribute. Therefore, patients can be injected during symptoms and imaged later after stabilization. The images that are obtained at that time reflect the ischemic state and coronary blood flow at the time of isotope injection. The favorable energy and dosimetry of Tc also allows gated acquisition and reconstruction of dynamic functional images, thereby providing simultaneous assessment of both regional and global ventricular functions that can be correlated with perfusion defects. By using computer algorithms, ejection fraction can be quantitatively obtained. The value of incorporating gating into acute MPI interpretation has been under-recognized. Kontos et al analyzed outcomes from 2,826 consecutive patients admitted after undergoing acute rest MPI. Overall images were interpreted as abnormal in 40% and normal in 32%. Patients who had perfusion defects but with normal wall motion (27%) were considered negative for ACS and classified as non-acute MPI. Event rates were similar and not significantly different for those with From the Departments of Internal Medicine, Emergency Medicine and Radiology, VCU Medical Center, Virginia Commonwealth University, Richmond, VA. Adapted from a presentation at American Society of Nuclear Cardiology, Philadelphia, PA, September 2010. Reprint requests: Michael C. Kontos, MD, FACC, FAHA, Departments of Internal Medicine, Emergency Medicine and Radiology, VCU Medical Center, Virginia Commonwealth University, Room 285 Gateway Building, Second Floor, 1200 E Marshall St., P.O. Box 980051, Richmond, VA 23298-0051; mkontos@mcvh-vcu.edu, mckontos@vcu.edu. J Nucl Cardiol 2011;18:342–50. 1071-3581/$34.00 Copyright 2011 American Society of Nuclear Cardiology. doi:10.1007/s12350-011-9349-0

Endocrine Society of India management guidelines for patients with thyroid nodules: A position statement

Thyroid nodules are common. Thyroid cancer is rarer. No guidelines exist for management of thyroid nodules in the Indian context and these recommendations are intended for this purpose. The consensus committee reviewed important articles, including previously published consensus statements. Management points were scored according to the level of evidence. These guidelines cover the clinical evaluation and include the interpretation of imaging and fine needle aspiration cytology of thyroid nodules. The guidelines also cover the management of special situations like thyroid incidentalomas, cystic thyroid lesion and nodules detected during pregnancy. The consensus guidelines represent a summary of current medical evidence for thyroid nodule management and the committee has attempted to optimize the guidelines for the clinical practice setting in India.

Gas-phase isothermal chromatography with short-lived technetium isotopes

Abstract In order to study the gas-phase chemical behavior of transactinides, an on-line isothermal chromatography apparatus has been developed and applied to separate short-lived technetium isotopes in the form of TcO3 from fission products. The fission products from a 252Cf source were continuously and rapidly transported through the capillary to the isothermal chromatography apparatus using the N2/KBr gas-jet techniques. Volatile oxide molecules were formed at the reaction zone kept at 900 °C since a trace amount of oxygen existed in the N2 carrier gas. With the new developed isothermal chromatography apparatus, a selective separation of Tc from fission products was achieved. After isothermal chromatographic separation, 101,103,104,105,106,107,108Tc were dominantly observed together with their Ru daughters in the γ-spectrum, The chemical yields of 101Tc, 104Tc and 105Tc isotopes with longer half-lives are about 55−57%, and those of 103Tc, 106Tc, 107Tc and 108Tc isotopes with shorter half-lives dropped down to 25−28%. The adsorption enthalpy of the investigated compounds on quartz surfaces was determined to be −150±5 kJ/mol by fitting the measured retention curves with a Monte Carlo model. The observed species of technetium oxide is attributed to TcO3, which is in good agreement with previous experimental results. That means our system worked properly and it can be used to investigate the gas-phase chemical behavior of transactinides.

Speciation of Technetium(IV) in Bicarbonate Media

The technetium isotope (99)Tc is a major fission product from nuclear reactors. Ultimately it is disposed of as radioactive waste since it has few applications outside of scientific research. Geochemical modeling of the dissolution of nuclear waste and of the solubility and speciation of the dissolved radionuclides in groundwater is an important part of the Performance Assessment for the safety of nuclear waste repositories. It relies on the availability of a critically assessed thermodynamic database. The potential of the Tc(VII)/Tc(IV) redox couple is measured here under various chemical conditions to verify the stoichiometries of Tc complexes and determine their stabilities: (i) -log(10)[H(+)] in the range 7.0-10.0, for 0.3, 0.6, and 0.7 M [CO(3)](total); (ii) [CO(3)](total) in the range 0.01-0.6 M at -log(10)[H(+)] approximately 8.6; and (iii) [Tc(VII)]/[Tc(IV] ratios of (6.02 10(-5) M)/(10(-6) M) and (6.02 10(-5) M)/(6.02 10(-5) M) at -log(10)[H(+)] = -9.1 and [CO(3)](total) = 1 M. Assuming that Tc(VII), TcO(4)(-) is the only species which exists under all the above chemical conditions, the potentiometric results can be interpreted by considering the presence of two hydroxide-carbonate monomeric complexes. The hydrolysis equilibrium between these two complexes is Tc(CO(3))(OH)(2) + H(2)O <--> Tc(CO(3))(OH)(3)(-) + H(+) with -log(10)[H(+)](1/2) = 8.69 +/- 0.20, which is consistent with the -8.3 +/- 0.6 corresponding hydrolysis constant of the NEA TDB review. 733 +/- 44 mV/SHE and 575 +/- 60 mV/SHE are measured for the standard potentials of the TcO(4)(-)/Tc(CO(3))(OH)(2), and for the TcO(4)(-)/Tc(CO(3))(OH)(3)(-) redox couples respectively. The corresponding formation constants from TcO(OH)(2) are log(10)K(1,2) = 19.8 +/- 0.5 and log(10)K(1,3) = 10.5 +/- 0.5, to be compared with the 19.3 +/- 0.3 and 11.0 +/- 0.6 values proposed by the NEA TDB review. Note that these values have been converted for the formation reactions described here, thus the given values are not those of the NEA TDB review. However, Tc(CO(3))(OH)(2) is predicted to dominate over a surprisingly large range of chemical conditions. The monomeric character of the Tc(IV) complexes is verified in this study.

PRODUCTION OF FISSION-LIKE EVENTS AFTER COMPLETE AND/OR INCOMPLETE FUSION OF16OWITH159TbAND169TmATE/A≈MeV

With a view to study heavy-ion induced fission after complete and/or incomplete fusion reactions, experiments have been performed at the Inter-University Accelerator Center (IUAC), New Delhi, India. The production cross-sections for more than 40 fission-like events (25 ≤ Z ≤ 45) produced in16O +159Tb and16O +169Tm systems, respectively, at E/A = 5.6 and 5.9 MeV have been measured using the recoil-catcher technique followed by off-line γ-spectroscopy. The analysis of the data indicates that fission is one of the competing modes of de-excitation of excited composite system formed via complete and/or incomplete fusion processes, where the evaporation of light nuclear particle(s) are more likely to be expected. Attempts have also been made to study isotopic yield distributions of Yttrium (83, 84m, 85, 87mY ) and Strontium (80, 81, 83, 85mSr ) isotopes in16O +159Tb system, and Indium (105, 107, 108, 110In ) and Technetium (99m, 101, 104, 105Tc ) isotopes in16O +169Tm system. The statistical analysis of the isotopic yield distribution has also been carried out to determine the most probable values of mass and charge of fission-like events in two systems.

Results of search for heavy neutron clusters in nuclear fission

Experiments on search for heavy neutron clusters in the reaction of induced fission of 235U nuclei by neutrons have been carried out on the nuclear reactor, using the activation method. Two hypothetical reactions have been investigated: 92Mo, 94Mo, 95Mo, 96Mo, 98Mo, 100Mo(xn, (x − k)n)105Mo → 105Tc → 105Ru → 105Rh → 105Pd, with a minimum transfer of 5 to 13 neutrons to activated Mo isotopes, and 122Te(xn, (x − k)n)122 + kTe → (β−) → 122 + kI, with a minimum transfer of 10 neutrons to activated 122Te isotope. Radiochemical methods for selecting technetium isotopes from molybdenum and iodine from tellurium were used. For the first reaction, the upper limit on the probability of neutron cluster formation was found to be Pk ≤ 10−8 per fission. For the second reaction, indications to the existence of heavy neutron clusters were obtained.

Challenges in Cardiac Risk Assessment in Bariatric Surgery Patients

Bariatric surgery has serious associated medical comorbidity and procedure-related risks and is thus considered an intermediate- to high-risk noncardiac surgery. Most patients referred for bariatric surgery have a low or very low functional capacity, making cardiac risk assessment imperative. Stress echocardiography has a high negative predictive value and can avoid some of the table weight and torso diameter problems associated with myocardial perfusion imaging. Echocardiograph contrast agents improve the ability to identify endocardial borders and assess ventricular wall motion and may be used with stress and nonstress imaging protocols. Single photon emission computer tomography (SPECT) imaging with attenuation correction, combined supine and prone imaging, use of technetium isotope, and positron emission tomography (PET) imaging may all provide some advantage for myocardial perfusion imaging for the obese patient.

Track structure simulation for positron emitters of physical interest. Part II: The case of the radiometals

The development of radiochemical services in hospitals, due to the wide use of Positron Emission Tomography (PET) in nuclear medicine, has led to the synthesis of new radiotracers among them radiometals which present a large panel of advantages in terms of half-life times and emission spectra. The most encouraging are the copper isotopes 62Cu and 64Cu as well as 60Cu and 61Cu and the technetium isotope 94mTc used for diagnosis and pharmacokinetic studies. The manganese isotopes 52mMn, 52Mn and 51Mn also present some interesting characteristics, especially 52mMn produced during the decay of 52Fe. Finally, the less known isotopes 89Zr, 45Ti, and 86Y can also be used as surrogates of some therapeutic agents, whereas 38K, 55Co and 66Ga may be used as PET imaging tracers. In this work, we propose an intercomparison of these PET radiometal isotopes. To do that, we have used the home-made Monte Carlo simulation previously described in Champion and Le Loirec [Phys. Med. Biol. 51 (2006) 1707] to simulate the complete decay of β + tracers in biological matter. Under these conditions, we access to a complete description of the positronic irradiation during PET exams using metallic isotopes. The results obtained are also compared with existing theoretical and experimental data and good agreement is generally observed.

Current Status of the Thermodynamic Data for Technetium and Its Compounds and Aqueous Species

The technetium isotope 99Tc is a major fission product from nuclear reactors. Because 99Tc has few applications outside of scientific research, most of this technetium will ultimately be disposed of as nuclear waste. Geochemical modeling of the dissolution of nuclear waste, and of the solubility and speciation of the dissolved radionuclides in groundwaters, is an important part of the Performance Asssessment of the safety of a nuclear waste repository that relies on the availability of a critically-assessed thermodynamic database. Such a database for technetium was published in the book Chemical Thermodynamics of Technetium, covering the published literature through 1998. This database is described here, along with a discussion of more recent relevant studies. Gaps in the knowledge of the chemical and thermodynamic properties of technetium are identified here, and recommendations are made for measurements that are required to eliminate these gaps.

Experimental partitioning of Tc, Mo, Ru, and Re between solid and liquid during crystallization in Fe-Ni-S

Technetium isotopes 97Tc, 98Tc and 99Tc decay to 97Mo, 98Ru and 99Ru, with half-lives of 2.6 My, 4.1 My, and 0.21 My respectively. If there were early solar system processes that resulted in significant fractionation of Tc from the daughter elements, decay of extant Tc could have led to the creation of Mo and Ru isotopic heterogeneities. To assess the potential of metallic core crystallization to fractionate these elements, we examine the partitioning behavior of Tc relative to Re, Mo and Ru in the Fe-Ni-S system between solid metal and liquid metal alloy. The experimental evidence shows that Tc behaves more like the modestly compatible siderophile element Ru than the more highly compatible siderophile element Re, and that Tc is substantially more compatible than Mo. We also demonstrate a pressure effect in the partitioning of Mo during the crystallization of Fe-Ni-S melts. For a sulfur concentration in the liquid fraction of the core of 10 wt% (16.3 at%), the Jones and Malvin (1990) parameter is −ln(1–2 × 1.09 × 0.163) ≅ 0.44, which yields: D(Re) ≅ 4.1; D(Ru) ≅ 2.3; D(Tc) ≅ 1.7; D(Mo) Lo-P ≅ 1.0;.and D(Mo) Hi-P ≅ 0.5. Our results suggest that detectable Tc-induced isotopic anomalies (≥0.1 ε unit) in Ru and Mo could only be produced by unrealistically extreme degrees of crystallization of metal during asteroidal core fractionation, regardless of the time scales and initial Tc abundances involved.

CARBORANES FOR NUCLEAR MEDICINE

A SYNTHETIC STRATEGY TO PREpare technetium(I) and rhenium (I) carboranes suitable for use as diagnostic and therapeutic reagents has been reported by assistant professor of chemistry John F. Valliant and coworkers at McMaster University in Hamilton, Ontario [ Inorg. Chem ., 41 , 628 (2002)]. Interest in the compounds is twofold: Carboranes, boranes, and other boron species are being used to prepare new compounds for boron neutron capture therapies that are being investigated as selective treatments for cancers and rheumatoid arthritis. In addition, the 99 m Tc isotope's nearly ideal nuclear properties for imaging have made it the most widely used radionuclide in diagnostic medicine. The McMaster researchers react [N(CH 2 CH 3 ) 4 ] 2 [M(CO) 3 Br 3 ] (M = 99 Tc, Re) with the dicarbollide anion nido - (C 2 B 9 H 12 )- to yield the metallacarboranes {N(CH 2 CH 3 )4 ][M(CO)3(C 2 B 9 H 11 )]. In an intermediate step, the dicarbollide anion is first deprotonated. Because there are no stable technetium isotopes ...

Accelerator mass spectrometry of 99Tc

The measurement of low levels of 99Tc (T 1/2=213 ka) by accelerator mass spectrometry (AMS) is reported for the first time. Because there are no stable isotopes of technetium, the 99Tc content of a sample is determined from the ratio of 99Tc to a known trace amount of 103Rh. High-purity aluminium oxide constitutes the bulk of each sample. The contribution from the 99Ru isobar may be quantified and subtracted using 101Ru. In contrast to conventional AMS in which at least one isotope is measured as a beam current, here all three isotopes, 99Tc, 101Ru and 103Rh, are counted ion-by-ion in a propane-filled ionization chamber. This ionization chamber permits partial, but not complete, separation of 99Tc from 99Ru ions. The technique has been validated using a series of standards, as well as a set of five seaweed samples from an inter-laboratory comparison exercise. In addition, the technique has been used to measure the relative intensities of the Tc − and TcO m − ( m=1–4) negative ions from a Cs sputter ion source.

Volatilization of cobalt, technetium, and uranium isotopes from soils through salt amendment and calcination

The effects of alkali and alkaline earth metal chloride salts on the decontamination (through volatilization) of radionuclides from clay soils in a calcination process were examined. Calcium chloride was found to decontaminate 60 Co -containing soils to a maximum extent of about 65% of 60 Co present before treatment by calcination for 8 h at 1000°C with the addition of about 4 milliequivalents (meq) of chloride per gram of soil. Repeated calcination treatments raised the level of decontamination to 80%, but not beyond. Technetium could be removed from clay soils slightly more effectively using a similar salting and calcination process. No decontamination of strontium or uranium soils was found using this process under reducing or oxidizing conditions. The data presented indicate areas in which the presence of chlorides may result in problems in the thermal treatment of soils or similar matrices; however, no viable decontamination process was achieved.

Diagnosis and management of condylar resorption

Purpose: This article discusses the cause, appropriate diagnostic evaluation, and management of progressive condylar resorption. Patients and Methods: This retrospective study evaluated 28 adult patients with bilateral progressive condylar resorption. Investigation included serial clinical examination, lateral cephalograms, tomograms, and a technetium isotope bone scan when indicated. Twenty-two patients were managed by either condylectomy and reconstruction with a costochondral graft (n = 5 patients) or orthognathic surgery (n = 18 patients). One patient initially had orthognathic surgery and subsequently underwent condylectomy and costochondral grafting, making a total of 23 procedures on 22 patients. Six patients received no surgical treatment. All patients were observed at least 2 years postoperatively. Results: Of the 18 patients who underwent orthognathic surgery, four again demonstrated condylar resorption with recurrence of open bite and retrognathism. Four patients had a stable result, but currently have temporomandibular joint (TMJ) symptoms, whereas 10 patients had a stable result (no change in postoperative occlusion or jaw position) without TMJ symptoms. The five cases receiving condylectomy and costochondral grafting were stable and asymptomatic, with good mandibular function. Analysis of the 18 orthognathic surgery patients showed that relapse occurred in patients having bimaxillary surgery with mandibular advancements greater than 5 mm and with a preoperative posterior ramus height of less than 35 mm. Conclusion: The management of progressive condylar resorption remains controversial. Orthognathic surgery in this small sample was associated with a complication rate (relapse or TMJ dysfunction) of approximately 45% (8 of 18). In contrast, condylectomy and costochondral grafting appeared to produce stable and functional results. Further long-term outcome studies for patients with condylar resorption are needed to corroborate these results.