17,463 research outputs found
Application of CT in Diagnosing Carcinoma of the Maxillary Sinuses : PART 2: An Experimental Study of Pitfalls Encountered when Diagnosing Carcinoma of the Maxillary Sinuses with CT
No full text1982-03A phantom simulating the transverse section of the maxillary sinuses was constructed for experimentation with various CT scanners to study the following: (1) the occasional inability to image the very thin posterior-lateral walls which have no real bone defects, and (2) to verify whether or not the bony walls surrounding the maxillary sinuses are actually as thick as they appear on CT. The phantom was made of an acrylic cylinder containing three cavities simulating the maxillary sinuses and the nasal cavity and filled with water. The walls, made of thin aluminum and acrylic plates and placed between water and air, disappeared in some CT images. The thickness of the walls calculated from CT values was greater than the true thickness imaged by each CT scanner. The author stresses that in CT images, either experimentally or clinically, thin bony walls placed between water and air or fat tend to disappear, and that bony walls tend to appear thicker than their true thickenss.departmental bulletin pape
Coherent longitudinal optical phonon and plasmon coupling in the near-surface region of InN
No full textKidney absorbed radiation doses for [ 177 Lu]Lu-PSMA-617 and [ 177 Lu]Lu-PSMA-I&T determined by 3D clinical dosimetry.
No full textPURPOSE: For prostate-specific membrane antigen-directed radioligand therapy (PSMA-RLT), [ 177 Lu]Lu-PSMA-617 and [ 177 Lu]Lu-PSMA-I&T are the currently preferred compounds. Recent preclinical studies suggested ~30x higher kidney absorbed dose for [ 177 Lu]Lu-PSMA-I&T compared to [ 177 Lu]Lu-PSMA-617, which may lead to an increased risk of kidney toxicity. We performed two single-centre, prospective dosimetry studies with either [ 177 Lu]Lu-PSMA-617 or [ 177 Lu]Lu-PSMA-I&T, using an identical dosimetry protocol. We evaluated the absorbed doses of both 177 Lu-labelled radioligands in human kidneys. METHODS: 3D SPECT/computed tomography (CT) imaging of the kidneys was performed after PSMA-RLT in cancer patients with PSMA-positive disease and an adequate glomerular filtration rate (≥50 mL/min). Ten metastatic hormone-sensitive prostate cancer patients (mHSPC) were treated with [ 177 Lu]Lu-PSMA-617 and 10 advanced salivary gland cancer (SGC) patients were treated with [ 177 Lu]Lu-PSMA-I&T. SPECT/CT imaging was performed at five timepoints (1 h, 24 h, 48 h, 72 h, and 168 h post-injection). In mHSPC patients, SPECT/CT imaging was performed after cycles 1 and 2 (cumulative activity: 9 GBq) and in SGC patients only after cycle 1 (activity: 7.4 GBq). Kidney absorbed dose was calculated using organ-based dosimetry. RESULTS: The median kidney absorbed dose was 0.49 Gy/GBq (range: 0.34-0.66) and 0.73 Gy/GBq (range: 0.42-1.31) for [ 177 Lu]Lu-PSMA-617 and [ 177 Lu]Lu-PSMA-I&T, respectively (independent samples t test; P = 0.010). CONCLUSION: This study shows that the kidney absorbed dose for [ 177 Lu]Lu-PSMA-617 and [ 177 Lu]Lu-PSMA-I&T differs, with a ~1.5x higher median kidney absorbed dose for [ 177 Lu]Lu-PSMA-I&T. This difference in the clinical setting is considerably smaller than observed in preclinical studies and may not hamper treatments with [ 177 Lu]Lu-PSMA-I&T
Kidney absorbed radiation doses for [<sup>177</sup>Lu]Lu-PSMA-617 and [<sup>177</sup>Lu]Lu-PSMA-I&T determined by 3D clinical dosimetry
No full textPurpose For prostate-specific membrane antigen-directed radioligand therapy (PSMA-RLT), [177Lu]Lu-PSMA-617 and [177Lu]Lu-PSMA-I&T are the currently preferred compounds. Recent preclinical studies suggested ∼30x higher kidney absorbed dose for [177Lu]Lu-PSMA-I&T compared to [177Lu]Lu-PSMA-617, which may lead to an increased risk of kidney toxicity. We performed two single-centre, prospective dosimetry studies with either [177Lu]Lu-PSMA-617 or [177Lu]Lu-PSMA-I&T, using an identical dosimetry protocol. We evaluated the absorbed doses of both 177Lu-labelled radioligands in human kidneys. Methods 3D SPECT/computed tomography (CT) imaging of the kidneys was performed after PSMA-RLT in cancer patients with PSMA-positive disease and an adequate glomerular filtration rate (≥50 mL/min). Ten metastatic hormone-sensitive prostate cancer patients (mHSPC) were treated with [177Lu]Lu-PSMA-617 and 10 advanced salivary gland cancer (SGC) patients were treated with [177Lu]Lu-PSMA-I&T. SPECT/CT imaging was performed at five timepoints (1 h, 24 h, 48 h, 72 h, and 168 h post-injection). In mHSPC patients, SPECT/CT imaging was performed after cycles 1 and 2 (cumulative activity: 9 GBq) and in SGC patients only after cycle 1 (activity: 7.4 GBq). Kidney absorbed dose was calculated using organ-based dosimetry. Results The median kidney absorbed dose was 0.49 Gy/GBq (range: 0.34-0.66) and 0.73 Gy/GBq (range: 0.42-1.31) for [177Lu]Lu-PSMA-617 and [177Lu]Lu-PSMA-I&T, respectively (independent samples t test; P = 0.010). Conclusion This study shows that the kidney absorbed dose for [177Lu]Lu-PSMA-617 and [177Lu]Lu-PSMA-I&T differs, with a ∼1.5x higher median kidney absorbed dose for [177Lu]Lu-PSMA-I&T. This difference in the clinical setting is considerably smaller than observed in preclinical studies and may not hamper treatments with [177Lu]Lu-PSMA-I&T.</p
Quantitative 177 Lu SPECT (QSPECT) imaging using a commercially available SPECT/CT system
No full textPURPOSE: The combination of single photon emission computed tomography (SPECT) and computer tomography (CT) that incorporates iterative reconstruction algorithms with attenuation and scatter correction should facilitate accurate non-invasive quantitative imaging. Quantitative SPECT (QSPECT) may improve diagnostic ability and could be useful for many applications including dosimetry assessment. Using (177)Lu, we developed a QSPECT method using a commercially available SPECT/CT system. METHODS: Serial SPECT of (177)Lu sources (89-12,400 MBq) were acquired with multiple contiguous energy windows along with a co-registered CT, and were reconstructed using an iterative algorithm with attenuation and scatter correction. Camera sensitivity (based on reconstructed SPECT count rate) and dead-time (based on wide-energy spectrum count rate) were resolved by non-linear curve fit. Utilizing these parameters, a SPECT dataset can be converted to a QSPECT dataset allowing quantitation in Becquerels per cubic centimetre or standardized uptake value (SUV). Validation QSPECT/CT studies were performed on a (177)Lu cylindrical phantom (7 studies) and on 5 patients (6 studies) who were administered a therapeutic dose of [(177)Lu]octreotate. RESULTS: The QSPECT sensitivity was 1.08 x 10(-5) ± 0.02 x 10(-5) s(-1) Bq(-1). The paralyzing dead-time constant was 0.78 ± 0.03 µs. The measured total activity with QSPECT deviated from the calibrated activity by 5.6 ± 1.9% and 2.6 ± 1.8%, respectively, in phantom and patients. Dead-time count loss up to 11.7% was observed in patient studies. CONCLUSION: QSPECT has high accuracy both in our phantom model and in clinical practice following [(177)Lu]octreotate therapy. This has the potential to yield more accurate dosimetry estimates than planar imaging and facilitate therapeutic response assessment. Validating this method with other radionuclides could open the way for many other research and clinical applications
Prediction of [177Lu]Lu-DOTA-TATE therapy response using the absorbed dose estimated from [177Lu]Lu-DOTA-TATE SPECT/CT in patients with metastatic neuroendocrine tumour
No full textAbstract Background Peptide receptor radionuclide therapy (PRRT) with [177Lu]Lu-DOTA-TATE has shown efficacy in patients with metastatic neuroendocrine tumours (NETs). Personalised dosimetry is crucial to optimise treatment outcomes and minimise adverse events. In this study, we investigated the correlation between the tumour-absorbed dose (TAD) estimated from [177Lu]Lu-DOTA-TATE SPECT/CT and the therapeutic response. Method A retrospective analysis was conducted on patients with advanced well-differentiated NETs grades 1–3 who underwent PRRT and exhibited greater uptake than liver on pre-therapeutic [68Ga]Ga-DOTA-TOC PET/CT. Target lesions were selected based on the RECIST 1.1 and PERCIST 1.0 criteria using [177Lu]Lu-DOTA-TATE SPECT/CT and pre-therapeutic contrast-enhanced CT scans. For anatomical image analysis, the sum of the longest diameter (SLD) of the target lesions was measured using the RECIST 1.1 criteria for patient-based analysis and the longest diameter (LD) of the target lesion using the RECIST-L criteria for lesion-based analysis. Standardised uptake values (SUVs) were measured on SPECT/CT images, and TADs were calculated based on the SUVs. Dosimetry was performed using a single SPECT/CT imaging time point at day 4–5 post-therapy. Statistical analyses were conducted to investigate correlations and determine the target lesion responses. Results Twenty patients with primary tumour sites and hepatic metastases were included. Fifty-five target lesions, predominantly located in the pancreas and liver, were analysed. The cumulative TAD (lesion-based analysis: r = 0.299–0.301, p = 0.025–0.027), but not the cycle 1 SUV (lesion-based analysis: r = 0.198–0.206, p = 0.131–0.147) or cycle 1 TAD (lesion-based analysis: r = 0.209–0.217, p = 0.112–0.126), exhibited a significant correlation with the change in LD of the target lesion. Binary logistic regression analysis identified the significance of the cumulative TAD in predicting disease control according to the RECIST-L criteria (odds ratio = 1.031–1.051, p = 0.024–0.026). Conclusions The cumulative TAD estimated from [177Lu]Lu-DOTA-TATE SPECT/CT revealed a significant correlation with change in LD, which was significantly higher for the cumulative TAD than for the cycle 1 SUV or TAD. A higher cumulative TAD was associated with disease control in the target lesion. However, considering the limitations inherent to a confined sample size, careful interpretation of these findings is required. Estimation of the cumulative TAD of [177Lu]Lu-DOTA-TATE therapy could guide the platform towards personalised therapy
EANM-EAU consensus on PSMA PET/CT in respect to radioligand therapy ([177Lu]Lu-PSMA)
No full textBackground
Prostate-specific membrane antigen (PSMA) positron emission tomography (PET)/computed tomography (CT) is useful for selected clinical indications in patients with prostate cancer (PCa) but it may have broader clinical utility owing to the emergence of lutetium-177-PSMA-617 ([177Lu]Lu-PSMA) therapy. However, robust data regarding the impact of PSMA PET/CT on patient management and treatment are lacking, and in many areas, the role of next-generation imaging has not been defined.
Objective
To assess expert opinion on the use of PSMA-based imaging and therapy to develop interim guidance.
Design, setting, and participants
A panel of 21 PCa experts from various disciplines received thematic topics and relevant literature. A questionnaire to assess proposed guidance statements regarding PSMA PET/CT and [177Lu]Lu-PSMA therapy was developed for completion remotely in a first e-Delphi round. A subsequent panel discussion was conducted during a 1-d meeting, which included a second Delphi round.
Outcome measurements and statistical analysis
Panellists voted anonymously on statements using a nine-point Likert scale from 1 = strongly disagree to 9 = strongly agree. Median scores were calculated and consensus was assessed using methods proposed by the Research and Development (RAND) corporation.
Results and limitations
Statements were developed to cover the following topics: PSMA PET/CT utility, clinical use, and choice of tracer; patient selection; and management of patients receiving [177Lu]Lu-PSMA for metastatic PCa. Consensus was reached for 33/36 statements. In-group bias is a potential limitation, as some statements were rephrased during discussions at the 1-d meeting.
Conclusions
Adoption of PSMA PET/CT as an imaging tool to guide [177Lu]Lu-PSMA therapy should be supported by indications for appropriate use.
Patient summary
A panel of experts in prostate cancer reached a consensus for the majority of statements proposed regarding the role of prostate-specific membrane antigen (PSMA)-based imaging and therapy, particularly the use of PSMA-based imaging in patients suitable for [177Lu]Lu-PSMA therapy and the need to perform PSMA-based imaging before considering patients as candidates for this therapy
Lu-177-Labeled Antibodies for EGFR-Targeted SPECT/CT Imaging and Radioimmunotherapy in a Preclinical Head and Neck Carcinoma Model
No full textEpidermal growth factor receptor (EGER) has been well characterized as an important target for cancer therapy. Immunotherapy based on EGFR-specific antibodies (e.g., panitumumab and cetuximab) has shown great clinical promise. However, increasing evidence has indicated that only a subgroup of patients receiving these antibodies will benefit from them, and even patients who do initially experience a major response may eventually develop therapeutic resistance. In this study, we investigated whether panitumumab and cetuximab can serve as delivery vehicles for tumor-targeted radionuclide therapy in a preclinical tumor model that did not respond to immunotherapy. The in vitro toxicity and cell binding properties of panitumumab and cetuximab were characterized. Both antibodies were conjugated with 1,4,7,10-tetraazadodecane-N,N',N '',N'''-tetraacetic acid (DOTA) and radiolabeled with Lu-177. Small-animal SPECT/CT, biodistribution, and radioimmunotherapy (RIT) studies of Lu-177-DOTA-panitumumab (Lu-177-Pan) and Lu-177-DOTA-cetuximab (Lu-177-Cet) were performed in the UM-SCC-22B tumor model. Both Lu-177-Pan and Lu-177-Cet exhibited favorable tumor targeting efficacy. The tumor uptake was 20.92 +/- 4.45, 26.10 +/- 5.18, and 13.27 +/- 1.94% ID/g for Lu-177-Pan, and 15.67 +/- 3.84, 15.72 +/- 3.49, and 7.82 +/- 2.36% ID/g for Lu-177-Cet at 24, 72, and 120 h p.i., respectively. RIT with a single dose of 14.8 MBq of Lu-177-Pan or Lu-177-Cet significantly delayed tumor growth. Lu-177-Pan induced more effective tumor growth inhibition due to a higher tumor uptake. Our results suggest that panitumumab and cetuximab can function as effective carriers for tumor-targeted delivery of radiation, and that RIT is promising for targeted therapy of EGFR-positive tumors, especially for those tumors that are resistant to antibody-based immunotherapy.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000332348600014&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Medicine, Research & ExperimentalPharmacology & PharmacySCI(E)[email protected]; [email protected]
Patient doses in ct, dental cone beam ct and projection radiography in Finland, with emphasis on paediatric patients
No full textDiagnostic radiology represents the largest man-made contribution to population radiation doses in Europe. To be able to keep the diagnostic benefit versus radiation risk ratio as high as possible, it is important to understand the quantitative relationship between the patient radiation dose and the various factors which affect the dose, such as the scan parameters, scan mode, and patient size. Paediatric patients have a higher probability for late radiation effects, since longer life expectancy is combined with the higher radiation sensitivity of the developing organs. The experience with particular paediatric examinations may be very limited and paediatric acquisition protocols may not be optimised.
The purpose of this thesis was to enhance and compare different dosimetric protocols, to promote the establishment of the paediatric diagnostic reference levels (DRLs), and to provide new data on patient doses for optimisation purposes in computed tomography (with new applications for dental imaging) and in paediatric radiography.
Large variations in radiation exposure in paediatric skull, sinus, chest, pelvic and abdominal radiography examinations were discovered in patient dose surveys. There were variations between different hospitals and examination rooms, between different sized patients, and between imaging techniques; emphasising the need for harmonisation of the examination protocols.
For computed tomography, a correction coefficient, which takes individual patient size into account in patient dosimetry, was created. The presented patient size correction method can be used for both adult and paediatric purposes. Dental cone beam CT scanners provided adequate image quality for dentomaxillofacial examinations while delivering considerably smaller effective doses to patient compared to the multi slice CT. However, large dose differences between cone beam CT scanners were not explained by differences in image quality, which indicated the lack of optimisation.
For paediatric radiography, a graphical method was created for setting the diagnostic reference levels in chest examinations, and the DRLs were given as a function of patient projection thickness. Paediatric DRLs were also given for sinus radiography. The detailed information about the patient data, exposure parameters and procedures provided tools for reducing the patient doses in paediatric radiography. The mean tissue doses presented for paediatric radiography enabled future risk assessments to be done. The calculated effective doses can be used for comparing different diagnostic procedures, as well as for comparing the use of similar technologies and procedures in different hospitals and countries.Diagnostisen röntgensäteilyn osuus ihmisen aiheuttamasta väestön keskimääräisestä säteilyannoksesta on kaikkein suurin. Jotta diagnostisen hyödyn ja säteilyhaitan välinen suhde voidaan pitää mahdollisimman suurena, on tärkeää ymmärtää kvantitatiivisesti potilaan säteilyannoksen ja siihen vaikuttavien tekijöiden, kuten kuvausarvojen, kuvausmenetelmien ja potilaiden kokojen välinen suhde. Lapsipotilailla on aikuisia suurempi riski säteilyn myöhäisiin haittavaikutuksiin, mikä on seurausta pitkästä odotettavissa olevasta eliniästä sekä kehittyvien elinten korkeasta säteilyherkkyydestä. Henkilökunnan kokemus tietyissä lasten tutkimuksissa voi olla rajallinen eikä lasten kuvausmenetelmiä välttämättä ole optimoitu.
Työn tarkoituksena oli kehittää ja vertailla eri annosmittausmenetelmiä tietokonetomografiatutkimuksissa (TT) ja lasten natiiviröntgentutkimuksissa, edistää lasten vertailutasojen käyttöönottoa sekä tuottaa uutta potilasannostietoa röntgentutkimusten optimointia varten.
Potilasannoskartoituksissa todettiin suuria vaihteluita kuvaustekniikoissa eri sairaaloiden, tutkimushuoneiden ja eri kokoisten potilaiden välillä. Tutkimustekniikoiden vaihtelusta aiheutuneet erot potilasannoksissa osoittivat tarvetta kuvausmenetelmien optimoinnille sekä kansallisella, että kansainvälisellä tasolla.
Tietokonetomografiatutkimuksia varten kehitettiin korjauskerroin, joka ottaa potilaan koon huomioon aikuisten ja lasten potilasannoksia määritettäessä. Tietokonetomografiatutkimuksissa lapset, naiset ja pienikokoiset potilaat absorboivat säteilyä suhteellisesti isokokoisia potilaita voimakkaammin. Hampaiston kuvantamisessa käytettävien rajoitetun kartiokeilan TT-laitteiden kuvanlaatu todettiin riittäväksi potilasannosten ollessa oleellisesti pienempiä kuin monileike-TT-laitteilla. Eri kartiokeila-TT-laitteiden potilasannoksissa oli kuitenkin suuria eroja kuvanlaadusta riippumatta, mikä osoitti tarvetta kuvaustekniikoiden jatkokehitykselle.
Lasten keuhkokuvauksia varten annettiin graafiset vertailutasot, joiden avulla sairaalat voivat suoraan verrata eri kokoisten potilaiden säteilyannoksia vertailutasoon. Vertailutasot annettiin myös lasten nenän sivuontelokuvauksia varten. Yksityiskohtaiset tiedot kerätystä aineistosta, kuvausarvoista ja -menetelmistä antoivat työkalut potilasannosten vähentämiseksi lasten natiiviröntgentutkimuksissa. Kudoksiin absorboituvien annosten määrittäminen mahdollistaa jatkossa potilaskohtaiset riskiarvioinnit. Määritettyjä efektiivisiä annoksia voidaan käyttää diagnostisten menetelmien ja kuvaustekniikoiden vertailuun eri sairaaloiden ja valtioiden välillä.ei saavutettav
Effect of bone marrow disease on hematologic toxicity and response to [Lu]Lu-PSMA-617 therapy: insights from PSMA-PET/CT imaging
No full textPURPOSE: Despite the effectiveness of [Lu]Lu-PSMA-617 in metastatic castration-resistant prostate cancer (mCRPC), hematologic toxicity remains a concern, particularly in patients with bone metastases. This study evaluated whether the extent, intensity, and heterogeneity of bone disease on pretreatment PSMA-PET/CT were associated with hematologic toxicity, PSA response, and overall survival (OS) in mCRPC patients treated with [Lu]Lu-PSMA-617. METHODS: This retrospective study included 96 mCRPC patients who underwent pretreatment PSMA-PET/CT and received standard-of-care [Lu]Lu-PSMA-617. Hematologic toxicity, PSA responses, and OS were analyzed in relation to quantitative PET parameters, including tumor volume, SUVmean, and heterogeneity of PSMA uptake in bone metastases. RESULTS: Clinically significant hematologic toxicity occurred in 19 patients (19.8%). Treatment discontinuation was more likely in those with a significantly higher (p = 0.007) percentage of total bone volume with PSMA-avid disease (median 28% vs. 1.7%). Those requiring dose delays or reductions (median 21% vs. 1.5%), blood transfusions (median 21% vs. 1.4%), and platelet transfusions (median 32% vs. 1.8%) also exhibited higher median percentages of total bone volume involvement (all p \u3c 0.01). Patients with more heterogeneous PSMA uptake had lower PSA50 response rates than those with more homogeneous uptake (30.3% vs. 64.5%, p = 0.002). A \u3e 50% difference between PSMA-low and PSMA-high bone disease was associated with significantly shorter OS (p \u3c 0.001). CONCLUSION: Extensive PSMA-avid bone involvement was associated with increased hematologic toxicity in mCRPC treated with [Lu]Lu-PSMA-617. Greater heterogeneity in PSMA uptake correlated with lower PSA50 response and OS but not hematologic toxicity. Careful patient selection and monitoring are needed, particularly in those with widespread bone disease
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