Support for the "Vancouver call for action to strengthen expertise in radiological protection worldwide": the position of organisations in formal relations with the International Commission on Radiological Protection (ICRP).

The International Commission on Radiological Protection (ICRP), recently expressed concern that "a shortage of investment in training, education, research, and infrastructure seen in many sectors and countries may compromise society's ability to properly manage radiation risks" and in 2022 announced the "Vancouver call for action to strengthen expertise in radiological protection worldwide". As representatives of organisations in formal relations with ICRP, we decided to promote this position paper to declare and emphasise that strengthening the expertise in radiological protection is a collective priority for all of us.

Whole-body radiation exposure in Trauma and Orthopaedic surgery.

AIMS: The use of fluoroscopy in orthopaedic surgery creates risk of radiation exposure to surgeons. Appropriate personal protective equipment (PPE) can help mitigate this. The primary aim of this study was to assess if current radiation protection in orthopaedic trauma is safe. The secondary aims were to describe normative data of radiation exposure during common orthopaedic procedures, evaluate ways to improve any deficits in protection, and validate the use of electronic personal dosimeters (EPDs) in assessing radiation dose in orthopaedic surgery. METHODS: Radiation exposure to surgeons during common orthopaedic trauma operations was prospectively assessed using EPDs and thermoluminescent dosimeters (TLDs). Normative data for each operation type were calculated and compared to recommended guidelines. RESULTS: Current PPE appears to mitigate more than 90% of ionizing radiation in orthopaedic fluoroscopic procedures. There is a higher exposure to the inner thigh during seated procedures. EPDs provided results for individual procedures. CONCLUSION: PPE currently used by surgeons in orthopaedic trauma theatre adequately reduces radiation exposure to below recommended levels. Normative data per trauma case show specific anatomical areas of higher exposure, which may benefit from enhanced radiation protection. EPDs can be used to assess real-time radiation exposure in orthopaedic surgery. There may be a role in future medical wearables for orthopaedic surgeons.Cite this article: Bone Jt Open 2022;3(11):907-912.

Development of a scatter correction technique for planar 99mTc-MAA imaging to improve accuracy in lung shunt fraction estimation.

PURPOSE: Prior to 90Y selective internal radiation therapy (SIRT) treatment, 99mTc-MAA scintigraphy imaging is used in the estimation of the lung shunt fraction (LSF). Planar imaging is recommended for determining a LSF ratio. However, the estimate may be affected by scatter contributions, attenuation and respiratory motion. The objective of this study was to correct for the effects of scatter in the LSF, towards the determination of a more accurate estimation method of LSF derived from planar scintigraphy imaging, which is recommended by international guidelines. METHODS: The open access SIMIND Monte Carlo modelling software was used to estimate an optimum scatter window (SW) for scatter correction. The uncertainties associated with scatter and scatter contributions from the liver on the LSF were evaluated using an anthropomorphic thorax phantom and a virtual Vox-Man phantom. A brief retrospective examination of patient scans and tumour location investigated the impact that the inclusion of the simulated scatter corrections had on the LSF estimation. RESULTS: The percentage overestimation of the manufacturer recommended method of LSF estimation was 192%. SW corrections improved the uncertainty to within 19% for the range of known LSFs. Similar findings were observed for our patient and tumour location studies. CONCLUSION: The incorporated scatter corrections can significantly improve the accuracy of the LSF estimation, thereby providing a robust gamma camera, patient and tumour depth specific correction which is easily implementable. This is supported by Monte Carlo, phantom and preliminary patient studies.

Patient radiation dose during angiography and embolization for abdominal hemorrhage: the influence of CT angiography, fluoroscopy system, patient and procedural variables.

BACKGROUND: Angiography and embolization (AE) is a lifesaving, high radiation dose procedure for treatment of abdominal arterial hemorrhage (AAH). Interventional radiologists have utilized pre-procedure CT angiography (CTA) and newer fluoroscopic systems in an attempt to reduce radiation dose and procedure time. PURPOSE: To study the factors contributing to the radiation dose of AE for AAH and to compare to the reference standard. MATERIALS AND METHODS: This retrospective single-centre observational cohort study identified 154 consecutive AE procedures in 138 patients (median age 65 years; interquartile range 54-77; 103 men) performed with a C-arm fluoroscopic system (Axiom Artis DTA or Axiom Artis Q (Siemens Healthineers)), between January 2010 and December 2017. Parameters analysed included: demographics, fluoroscopy system, bleeding location, body mass index (BMI), preprocedural CT, air kerma-area product (PKA), reference air kerma (Ka,r), fluoroscopy time (FT) and the number of digital subtraction angiography (DSA) runs. Factors affecting dose were assessed using Mann-Whitney U, Kruskal-Wallis one-way ANOVA and linear regression. RESULTS: Patients treated with the new angiographic system (NS) had a median PKA, median Ka,r, Q3 PKA and Q3 Ka,r that were 74% (p < 0.0005), 66%(p < 0.0005), 55% and 52% lower respectively than those treated with the old system (OS). This dose reduction was consistent for each bleeding location (upper GI, Lower GI and extraluminal). There was no difference in PKA (p = 0.452), Ka,r (p = 0.974) or FT (p = 0.179), between those who did (n = 137) or did not (n = 17) undergo pre-procedure CTA. Other factors significantly influencing radiation dose were: patient BMI and number of DSA runs. A multivariate model containing these variables accounts for 15.2% of the variance in Ka,r (p < 0.005) and 45.9% of the variance of PKA (p < 0.005). CONCLUSION: Radiation dose for AE in AAH is significantly reduced by new fluoroscopic technology. Higher patient body mass index is an independent key parameter affecting patient dose. Radiation dose was not influenced by haemorrhage site or performance of pre-procedure CTA.

MODELLING AUTOMATIC EXPOSURE CONTROL RESPONSE TO THE PRESENCE OF THE PATIENT SCANNING BED IN A HYBRID PET/CT SCANNER.

Automatic Exposure Control (AEC) systems optimise radiation dose to the patient while providing adequate image quality. This study examined the effect that the increased localiser region of interest of a hybrid PET/CT has on the CTDIvol, focussing on the role of extraneous objects and patient attenuation profiles. A Siemens Biograph™ 16 Horizon PET/CT system and a Siemens Somatom Sensation 64, both employing the Siemens CAREDose 4D AEC system, were used for acquisition of a range of phantoms. The effect of patient miscentring and effect of the patient bed impinging on the localiser was established and modelled. For PA localiser scans, a non-linear relationship between miscentring and CTDIvol was observed, attributable to the presence of the patient bed being misinterpreted as the patient width. The model identified how the presence of the patient bed led to an increase in the CTDIvol significantly larger than expected (~12%, or 1 mSv), particularly prevalent for smaller patients.

Assessment of occupational exposure from shielded and unshielded syringes for clinically relevant positron emission tomography (PET) isotopes-a Monte Carlo approach using EGSnrc.

18F has been the most widely used radionuclide in positron emission tomography (PET) facilities over the last few decades. However, increased interest in novel PET tracers, theranostics and immuno-PET has led to significant growth in clinically used positron-emitting radionuclides. The decay schemes of each of these radioisotopes are markedly different from18F, with different endpoint energies for the emitted positrons and, in some cases, additional high energy gamma radiation. This has implications for the occupational exposure of personnel involved in the manipulation and dispensing of PET radiopharmaceuticals. The EGSnrc Monte Carlo simulation software was used to estimate the doses to extremities in contact with unshielded and shielded syringes containing64Cu,18F,11C,13N,15O,68Ga and89Zr, respectively. Dose rates at various distances from the syringe were also modelled, with dose rates reported in terms of eye (Hp(3)), skin equivalent (Hp(0.07)) and deep (Hp(10)) doses. The composition and geometry of the simulated syringe shields were based on a selection of commercially available PET shields. Experimental dose rate measurements were performed for validation purposes where possible. Contact skin dose rates for all isotopes, except for64Cu, were found to be higher than18F for the unshielded syringe. The addition of a shield resulted in approximately equal contact skin dose rates for nearly all isotopes, for each shield type, with the exception of89Zr which was notably higher. Dose rate constants (µGy/MBq.hr) for a range of PET isotopes and shields are presented and their significance discussed.

Relative response of dosimeters to variations in scattered X-ray energy spectra encountered in interventional radiology.

PURPOSE: The new lower eye lens dose limit is of relevance in interventional radiology, where higher dose procedures result in increased scattered radiation to staff. The eye lens dose may be monitored using the directional dose equivalent at 3 mm depth, Hp(3), or through Hp(10) or Hp(0.07) measurements and using conversion factors. However, there are a considerable range of factors which contribute to measurement uncertainties, one of which is the incident photon energy. This study investigated the energy spectra of scattered radiation in interventional radiology, and the dosimetry accuracy of dosimeter types, evaluating their energy dependence. METHODS: Scatter X-ray energy spectra were recorded under varied conditions in a fluoroscopy imaging suite. Dosimetry accuracy of eye dosimeters, including TLDs (100 s, 100Hs), Landauer Hp(3), John Caunt ED3 and Electronic Personal dosimeters (EPDs) were compared to air kerma measurements across a range of tube voltages. RESULTS: The variation of energy spectra with changing phantom thickness, spectrometer angulation and filtration are presented. The 100 and 100H TLDs, and EPDs showed a consistent air kerma response (within 10%) with changes in energy. The real-time silicon diode detectors showed a variable over response of between 10 and 25% across the energies investigated while Landauers dedicated Hp(3) eye dosimeters showed considerable variation between dosimeters for similar conditions, a 17% variation at 50 kVp. CONCLUSION: The work aimed to validate the scattered energy spectra typically encountered in interventional radiology and to further determine the accuracy of eye dosimeters in relation to energy response variations.

Yttrium-90 selective internal radiation therapy, examining dose rates and radiation protection precautions.

METHODS: Dose rates from 30 patients, treated over a 3-year period (2016-2018) were measured post therapy in contact with the patients' upper abdomen and at distances of 0.3 m and 1 m. Dose rates were compared with theoretical predictions and used as model inputs for calculating radiation doses received by family members and carers based on interaction patterns previously described in the literature. RESULTS: The average dose rate per activity from SIRT patients were:- In contact: 29 ±â€¯23 µSv.h-1.GBq-1; 0.3 m: 4.1 ±â€¯2.34 µSv.h-1.GBq-1 and 1 m: 0.59 ±â€¯0.42 µSv.h-1.GBq-1. Dose rates measured at 0.3 and 1 m followed a predictable distribution. Estimated doses based on proximity models demonstrated restrictions to be advisable, depending on the administered activity, considering the dose constraint and limit of 0.3 and 1 mSv, respectively, employed within the EU. CONCLUSIONS: In accordance with local dose constraints, and depending on administered activities, radiation protection precautions may be necessary for those individuals in regular contact with patients who have receive 90Y SIRT. A radiation protection precautions calculator has been devised to offer personalised instructions taking into account the administered activity and proximity models.

Metabolic tumor volume provides complementary prognostic information to EUS staging in esophageal and junctional cancer.

To determine the correlation between 18F-fluorodeoxyglucose positron emission tomography-computed tomography (PET-CT) derived esophageal tumor parameters [maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV)] and endoscopic ultrasound (EUS) derived tumor parameters (T stage, N stage) and their prognostic implications. 150 consecutive patients with cancer of the esophagus or esophagogastric junction underwent staging PET-CT and staging EUS. PET-CT derived SUVmax and MTV of the primary tumor was recorded. EUS evaluated T and N stage. Relationships between parameters were investigated using the Mann-Whitney U tests, survival analysis performed using Kaplan-Meier and independent prognostic factors determined using Cox regression multivariate analysis. A significant difference in MTV was noted between EUS T1/T2 tumors (median 6.7 cm3) and EUS T3/T4 tumors (median 35.7 cm3; P < 0.0001). An MTV of <23.4 cm3 (P = 0.0001), SUVmax < 4.1 (P = 0014), EUS T stage (P < 0.0001), EUS N stage (P < 0.0001), and clinical stage (P < 0.0001) were all significantly associated with survival, with MTV <23.4 cm3 (P = 0.004), EUS T stage (P = 0.01), and EUS N stage (P = 0.01) significant in multivariate analysis. MTV, a volumetric parameter of PET-CT, has more prognostic importance than SUVmax and provides valuable prognostic information in esophageal and junctional cancer, along with EUS T and N stage. MTV provides complementary information to EUS and should be included in the staging of esophageal and junctional cancer.

Predictors of Outcome in Pediatric Osteomyelitis: Five Years Experience in a Single Tertiary Center.

BACKGROUND: Acute haematogenous osteomyelitis is a bacterial infection of bone, which occurs most frequently in children. Outcomes are excellent for the majority of children, but a minority develop complicated osteomyelitis. Predicting which children will develop complicated osteomyelitis remains a challenge, particularly in developed countries where most patients are discharged home after a relatively short period in hospital. METHODS: We conducted a 5-year retrospective case note review of all children aged 3 months to 16 years admitted with a diagnosis of acute haematogenous osteomyelitis. We compared standardized clinical and laboratory parameters in those who developed simple and complicated osteomyelitis. RESULTS: Of the 299 children who met inclusion, 241 (80.6%) had simple and 58 (19.4%) had complicated osteomyelitis. The major predictors of complicated disease were older age, a temperature greater than 38.5°C and a higher C-reactive protein at admission. CONCLUSIONS: A risk prediction model, utilizing information available shortly after hospitalization, allows early identification of children at greatest risk of developing complicated osteomyelitis.

Tenofovir-related Fanconi's syndrome and osteomalacia in a teenager with HIV.

A teenage boy with vertically acquired-HIV presented with bone pain of 6 months duration. His antiretroviral therapy (ART) consisted of tenofovir disoproxil fumarate (TDF), emtricitabine and ritonavir-boosted lopinavir. Plain X-rays showed stress fractures of metatarsals bilaterally. A dual emission X-ray absorptiometry scan revealed osteomalacia. Raised serum creatine, hypophosphataemia, glycosuria and metabolic acidosis supported a diagnosis of Fanconi's syndrome. Serum vitamin D levels were low. Discontinuation of TDF led to improvement in renal function, increase in serum phosphate and resolution of bone pain. This case uniquely features renal and skeletal toxicities with resultant metatarsal stress fractures. Children and adolescents on combined ART which include tenofovir should be screened for the early detection of proximal tubulopathy, with the measurement of renal function, phosphate, vitamin D and urinary phosphate excretion. Although uncommon and mostly reversible, recognition of tenofovir-related effects is paramount as prolonged exposure may lead to persistent renal tubular damage and osteomalacia.

(18)F-FDG PET-detected synchronous primary neoplasms in the staging of esophageal cancer: incidence, cost, and impact on management.

PURPOSE: F-Fluorodeoxyglucose positron emission tomography (F-FDG PET) imaging is increasingly the standard of care in the staging of esophageal cancer. Synchronous neoplasms may be identified, and this study evaluated the prevalence of such tumors and their impact on management. METHODS: Five hundred ninety-one (73.6%) of 803 consecutive patients with biopsy-proven esophageal cancer underwent staging F-FDG PET or PET/CT scans. F-FDG-avid lesions were considered synchronous primary neoplasms if occurring at locations atypical for metastases from the known primary, a marked discordance in the F-FDG avidity from that of the primary tumor, and if there was no prior detection on conventional imaging. Additional investigations as appropriate were undertaken, and histopathological verification was obtained where possible to validate the suspected synchronous neoplasm. RESULTS: A synchronous neoplasm was suspected in 55 (9.3%) of 591 patients, predominantly at sites in the colon (26) and head and neck (21). Additional investigations in 43 cases revealed malignant neoplasms in 8 (18.6%), premalignant in 9 (20.9%), and benign lesions in 26 (60.5%) cases. The management plan was altered in 8 patients, 1.4% overall. The total cost of added tests was $27,482.57 (&OV0556;21,024) with the decision to treat the esophageal cancer deferred by a mean of 10.7 days. CONCLUSION: F-FDG uptake concerning for synchronous neoplasms is evident in approximately 1 in 10 cases, and of these a minority will represent a malignant neoplasm that significantly impacts on treatment. The overall added costs per patient are relatively modest and the treatment delay within acceptable limits of clinical practice.

Early repeated 18F-FDG PET scans during neoadjuvant chemoradiation fail to predict histopathologic response or survival benefit in adenocarcinoma of the esophagus.

UNLABELLED: This study evaluated the role of (18)F-FDG PET as an early predictor of histopathologic response to neoadjuvant chemoradiotherapy and overall survival in patients with adenocarcinoma of the esophagus undergoing multimodal therapy. METHODS: Thirty-seven patients with locally advanced adenocarcinoma of the esophagus underwent pretreatment and an intratreatment (18)F-FDG PET scan in the second week of a 6-wk regimen of neoadjuvant chemoradiotherapy. Histopathologic response and overall survival were correlated with percentage change in (18)F-FDG uptake (%Δmaximum standardized uptake value [%ΔSUVmax]). RESULTS: In 16 patients (43%), treatment induced a histopathologic response (<10% viable tumor cells), which was associated with a significant (P < 0.05) survival benefit. The optimal reduction in (18)F-FDG uptake, which separated histopathologic responders and nonresponders, was a -26.4% ΔSUVmax (receiver-operating-characteristic curve analysis). At this separation, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy (area under the receiver operating characteristic curve) were 62.5%, 71.4%, 62.5%, 71.4%, and 67.4%, respectively, for intratreatment (18)F-FDG PET scans. Kaplan-Meier survival analysis of (18)F-FDG PET responders (>26.4% reduction in SUVmax), compared with (18)F-FDG PET nonresponders (<26.4% reduction in SUVmax), revealed no survival benefit for responders (P = 0.6812). CONCLUSION: The %ΔSUVmax during the second week of induction chemoradiation did not correlate either with histopathologic response or with survival. Our results show that, in contrast to published reports on neoadjuvant chemotherapy, combined chemoradiotherapy in patients with adenocarcinoma of the esophagus lowers the predictive accuracy of early repeated (18)F-FDG PET in identifying histopathologic responders and those with chances for increased survival below clinically applicable levels.

Clinical implication and prognostic significance of standardised uptake value of primary non-small cell lung cancer on positron emission tomography: analysis of 176 cases.

OBJECTIVE: We sought to assess the clinical implication and prognostic significance of maximum standardised uptake value (SUV(max)) of primary non-small cell lung cancer (NSCLC) staged by integrated PET-CT. METHODS: A retrospective review was carried out on 176 consecutive patients with histologically proven NSCLC who underwent staging with integrated PET-CT prior to curative intent surgical resection. SUV(max) of primary NSCLC were measured and correlated with tumour characteristics, lymph node involvement, surgical stage, type of surgical resection and survival following resection. RESULTS: SUV(max) was significantly higher in centrally located tumours, tumours > or =4.0 cm, squamous cell subtype, poorly differentiated tumours, advanced T stage, advanced nodal stage, pleural invasion, and patients requiring complex surgical resection. SUV(max) value of 15 was the best discriminative cut-off value for survival generated by log-rank test. When patients were stratified based on this value, those with SUV(max) >15 were more likely to have centrally located tumours, squamous cell subtype, advanced T stage, advanced nodal stage, advanced American Joint Committee on Cancer (AJCC) stage, larger tumour size and required more advanced surgical resections than a simple lobectomy. Overall survival was significantly longer for patients with SUV(max) < or =15 than those with SUV(max) >15. Furthermore, nodal stage specific survival following resection (i.e. non-N2 and N2) were significantly better in patients with SUV(max) < or =15 than SUV(max) >15. CONCLUSION: SUV(max) correlates with tumour characteristics, surgical stage and prognosis following resection. SUV(max) may be a useful preoperative tool, in addition to other known prognostic markers, in allocating patients with potentially poor prognosis preoperatively to neoadjuvant chemotherapy prior to resection in order to improve their overall survival. Prospective and randomised trials are warranted.

Mediastinal lymph node staging by means of positron emission tomography is less sensitive in elderly patients with non-small-cell lung cancer.

PURPOSE: We sought to identify the impact of age on the sensitivity and specificity of integrated positron emission tomography/computed tomography (PET-CT; CT) on mediastinal lymph node staging of patients with non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: We conducted a retrospective review of 206 consecutive patients with histologically proven NSCLC who underwent resection and/or mediastinoscopy in our center between September 2004 and January 2007. All of these patients had preoperative staging with integrated PET-CT as an adjunct to chest CT before resection and/or mediastinoscopy. Diabetic patients and patients who received neoadjuvant chemotherapy were excluded. The pathologic results of all of these cases were reviewed and correlated with those on CT and integrated PET-CT. RESULTS: The sensitivity and positive predictive values (PPV) of PET-CT in mediastinal nodal staging were significantly lower in elderly patients (age>or=65 years; sensitivity, 42%; PPV, 66%) than in younger patients (age<65 years; sensitivity, 52%; PPV, 74%). Specificity and negative predictive values were similar in both groups. CONCLUSION: PET-CT staging of the mediastinum is less sensitive in elderly patients with NSCLC who have a lower PPV. Positive mediastinal uptake on PET-CT should be verified by mediastinoscopy, irrespective of age. Elderly patients with positive mediastinal uptake should not be refuted a curative intent surgical resection on the basis of positive mediastinal uptake alone.

Lymph node staging by means of positron emission tomography is less accurate in non-small cell lung cancer patients with enlarged lymph nodes: analysis of 1,145 lymph nodes.

BACKGROUND: Despite documented superiority of integrated positron emission tomography-computerized tomography (PET-CT) over computerized tomography (CT) in lymph node staging in non-small cell lung cancer, little is known about the sensitivity, specificity and accuracy of integrated PET-CT among enlarged lymph nodes. We sought to assess if PET-CT is uniformly accurate among enlarged and non-enlarged lymph nodes. METHODS: A retrospective review of 206 consecutive patients with histologically proven non-small cell lung cancer who underwent resection and/or mediastinoscopy in our centre over 30 months period was carried out. All these patients had pre-operative staging with integrated PET-CT as an adjunct to chest CT prior to resection and/or mediastinoscopy. Diabetic patients (BM>or=8.0 mmol/l) and those who received neo-adjuvant chemotherapy were excluded. The pathological results of all these cases were reviewed and correlated with those on CT and integrated PET-CT. RESULTS: The sensitivity, specificity, accuracy, positive and negative predictive values were higher in integrated PET-CT than CT alone in all lymph nodes, whether N1 or N2. When lymph nodes were stratified by size, the sensitivity of PET-CT was significantly higher among enlarged (>1cm) than non-enlarged (1cm) should be with caution as the specificity of PET-CT is lower and its ability to detect truly negative nodes become reduced. NSCLC patients with enlarged nodes by CT criteria who are PET-CT negative may require cervical mediastinoscopy to rule out metastatic spread to these nodes. Prospective studies are warranted.

Pattern and predictors of occult mediastinal lymph node involvement in non-small cell lung cancer patients with negative mediastinal uptake on positron emission tomography.

OBJECTIVE: We sought to assess the incidence, pattern and predictors of occult mediastinal lymph node involvement (N2) in non-small cell lung cancer patients with negative mediastinal uptake of 2-deoxy-2-[(18)F]-fluoro-d-glucose ((18)FDG) on integrated positron emission tomography-computerised tomography (PET-CT). METHODS: All patients who underwent surgical resection in our unit over a 30-month period were reviewed (n=215). All patients had preoperative PET-CT prior to lung resection as an adjunct to a dedicated chest CT. Diabetic patients, patients who received neoadjuvant chemotherapy and those with positive mediastinal nodes on PET-CT (N2/N3) were excluded from this study. The population of interest was 153 non-small cell cancer patients (NSCLC), all of which had no FDG uptake in the mediastinum. No preoperative mediastinoscopy was carried out in this group and all underwent curative intent surgical resection. The pathological results were retrospectively reviewed and correlated with CT and integrated PET-CT findings. RESULTS: The incidence of occult N2 disease in NSCLC patients with negative mediastinal uptake of (18)FDG on PET-CT was 16% (25 of 153). The highest incidence of occult N2 involvement was in American thoracic society (ATS) 7 (16 of 25 patients, 64%) followed by ATS 4 (seven patients of 25, 28%). In univariate analysis, the following were significant predictors of occult N2 disease: centrally located tumours (P=0.049), right upper lobe tumours (P=0.04), enlarged lymph nodes (>1cm) on CT (P=0.048) and PET positive uptake in N1 nodes (P=0.006). In multivariate analysis, the following were independent predictors of occult N2 disease: centrally located tumours, right upper lobe tumours and PET positive uptake in N1 nodes (P<0.05). CONCLUSIONS: In NSCLC patients who are clinically staged as N2/N3 negative in the mediastinum by integrated PET-CT, 16% will have occult N2 disease following resection. Patients with the following: centrally located tumours, right upper lobe tumours and positive N1 nodes on PET should have preoperative cervical mediastinoscopy to rule out N2 nodal involvement, especially in ATS stations 7 and 4 as the incidence of occult nodal metastasis in these nodes is high. This study has potential implications in decision-making and planning best treatment approach.

A novel approach to the sequential extraction of plutonium from oxic and anoxic sediment using sodium citrate to inhibit post-extraction resorption.

Sequential extraction has been used extensively to study the solid partitioning of radionuclides in soils and sediments. A difficulty with sequential extraction is that radionuclides released by a particular extractant can be resorbed and artificially redistributed amongst the remaining solid phases. Here, we describe experiments (on selected model phase and natural materials), which were designed to determine whether the inclusion of a chelating agent (sodium citrate) in an established sequential extraction protocol (a) inhibits post-extraction resorption of plutonium, (b) increases non-targeted dissolution of sediment phases, and (c) gives rise to unwanted ligand competition for plutonium. The results clearly demonstrate the capacity of citrate to inhibit the resorption of plutonium from the various extractants, and confirm that there is no discernible increase in non-targeted phase dissolution, but indicate significant ligand competition with the carbonate phase. The merits of using citrate are discussed and an optimised sequential extraction protocol that includes citrate is proposed. Finally, the protocol is applied to oxic and anoxic sediments sampled in the NE Irish Sea and the Roads of Cherbourg, and it is shown that the bulk of the plutonium on these sediments is associated with the more labile geochemical fractions.