| 1. |
- Al-Olama, Mohamed, et al.
(författare)
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The peptide AF-16 decreases high interstitial fluid pressure in solid tumors.
- 2011
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Ingår i: Acta oncologica (Stockholm, Sweden). - 1651-226X.
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Tidskriftsartikel (refereegranskat)abstract
- Abstract Background. The high interstitial fluid pressure (IFP) in solid tumors restricts the access to nutrients, oxygen and drugs. Material and methods. We investigated the ability of the peptide AF-16, involved in water and ion transfer through cell membranes, to lower the IFP in two different solid rat mammary tumors, one chemically induced, slowly growing, and the other transplantable, and rapidly progressing having high cellularity. AF-16 was administered either in the tumor capsule, intranasally or intravenously. The IFP was measured by a miniature fiber optic device. Results. AF-16 significantly lowered the IFP in both the slowly and the rapidly progressing tumors, whether administrated locally or systemically. The AF-16 induced IFP reduction was maximal after 90 min, lasted at least 3 h, and returned to pretreatment levels in less than 24 h. Topical AF-16 transiently reduced the IFP in the DMBA tumors from 17.7 ± 4.2 mmHg to 8.6 ± 2.1 mmHg. Conclusion. We conclude that AF-16 transiently and reversibly lowered the high IFP in solid tumors during a few hours, which might translate into improved therapeutic efficacy.
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| 2. |
- Cederkrantz, Elin, et al.
(författare)
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Evaluation of Effects on the Peritoneum After Intraperitoneal α-Radioimmunotherapy with (211)At.
- 2012
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Ingår i: Cancer biotherapy & radiopharmaceuticals. - : Mary Ann Liebert Inc. - 1557-8852 .- 1084-9785. ; 27:6, s. 353-364
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Tidskriftsartikel (refereegranskat)abstract
- Abstract The introduction of the short-lived α-emitter (211)At to intraperitoneal radioimmunotherapy has raised the issue of the tolerance dose of the peritoneum. The short range of the α-particles (70μm) and the short half-life (7.21h) of the nuclide yield a dose distribution in which the peritoneum is highly irradiated compared with other normal tissues. To address this issue, mice were injected with (211)At-trastuzumab to irradiate the peritoneum to absorbed doses ranging between 0 and 50 Gy and followed for up to 34 weeks. The peritoneum-to-plasma clearance of a small tracer, (51)Cr-ethylenediamine tetraacetic acid, was measured for evaluation of the small solute transport capacity of the peritoneal membrane. The macroscopic status of the peritoneum and the mesenteric windows was documented when the mice were sacrificed. Biopsies of the peritoneum were taken for morphology and immunohistochemical staining against plasminogen activator inhibitor-1 and calprotectin. Peritoneum-to-plasma clearance measurements indicated a dose-dependent decrease in peritoneal transport capacity in irradiated mice. However, macroscopic and microscopic evaluations of the peritoneal membrane showed no difference between irradiated mice versus controls. The results imply that the peritoneal membrane tolerates absorbed doses as high as 30-50 Gy from α-particle irradiation with limited response.
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| 3. |
- Chouin, Nicolas, et al.
(författare)
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Ex Vivo Activity Quantification in Micrometastases at the Cellular Scale Using the α-Camera Technique.
- 2013
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Ingår i: Journal of nuclear medicine : official publication, Society of Nuclear Medicine. - : Society of Nuclear Medicine. - 1535-5667. ; 54:8, s. 1347-1353
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Tidskriftsartikel (refereegranskat)abstract
- Targeted α-therapy (TAT) appears to be an ideal therapeutic technique for eliminating malignant circulating, minimal residual, or micrometastatic cells. These types of malignancies are typically infraclinical, complicating the evaluation of potential treatments. This study presents a method of ex vivo activity quantification with an α-camera device, allowing measurement of the activity taken up by tumor cells in biologic structures a few tens of microns. METHODS: We examined micrometastases from a murine model of ovarian carcinoma after injection of a radioimmunoconjugate labeled with (211)At for TAT. At different time points, biologic samples were excised and cryosectioned. The activity level and the number of tumor cells were determined by combined information from 2 adjacent sections: one exposed to the α-camera and the other stained with hematoxylin and eosin. The time-activity curves for tumor cell clusters, comprising fewer than 10 cells, were derived for 2 different injected activities (6 and 1 MBq). RESULTS: High uptake and good retention of the radioimmunoconjugate were observed at the surface of tumor cells. Dosimetric calculations based on the measured time-integrated activity indicated that for an injected activity of 1 MBq, isolated tumor cells received at least 12 Gy. In larger micrometastases (≤100 μm in diameter), the activity uptake per cell was lower, possibly because of hindered penetration of radiolabeled antibodies; however, the mean absorbed dose delivered to tumor cells was above 30 Gy, due to cross-fire irradiation. CONCLUSION: Using the α-camera, we developed a method of ex vivo activity quantification at the cellular scale, which was further applied to characterize the behavior of a radiolabeled antibody administered in vivo against ovarian carcinoma. This study demonstrated a reliable measurement of activity. This method of activity quantification, based on experimentally measured data, is expected to improve the relevance of small-scale dosimetry studies and thus to accelerate the optimization of TAT.
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| 4. |
- Claesson, Kristina, 1965, et al.
(författare)
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RBE of α-particles from 211At for complex DNA damage and cell survival in relation to cell cycle positio.
- 2011
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Ingår i: International journal of radiation biology. - : Informa UK Limited. - 1362-3095 .- 0955-3002.
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Tidskriftsartikel (refereegranskat)abstract
- Purpose:To investigate cell cycle effects and relative biological effectiveness (RBE) of α-particles from the clinically relevant radionuclide Astatine-211 ((211)At), using X-rays as reference radiation. Double-strand breaks (DSB), non-DSB clusters containing oxidised purines and clonogenic survival were investigated. Materials and methods:Asynchronous V79-379A fibroblasts or cells synchronised with mimosine in G1, early, mid and late S phase or in mitosis were irradiated with X-rays (100 kV(p)) or (211)At (mean linear energy transfer (LET) 110 keV/μm). Induction of DSB and clusters was determined using pulsed-field gel electrophoresis with fragment analysis. Cell survival was obtained with the clonogenic assay. Results:In asynchronous cells RBE for DSB- and cluster-induction was 3.5 and 0.59, respectively. RBE for 37% cell survival was 8.6. In different cell cycle phases RBE varied from 1.8-3.9 for DSB and 3.1-7.9 for 37% survival (survival at 2 Gy was 6.9-38 times lower after α-irradiation). (211)At induced 6 times more DSB and X-rays induced 11 times more DSB in mitotic cells with highly compacted chromatin relative G1. Conclusions:The radio-response is cell cycle dependent and differs between proliferating and non-cycling cells for both low- and high-LET radiation, resulting in a variation in RBE of α-particles between 1.8 and 8.6.
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| 5. |
- Danielsson, Anna, 1973, et al.
(författare)
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Differential gene expression in human fibroblasts after alpha-particle emitter (211)At compared with (60)Co irradiation.
- 2013
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Ingår i: International journal of radiation biology. - : Informa UK Limited. - 1362-3095 .- 0955-3002. ; 89:4, s. 250-258
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: The aim of this study was to identify gene expression profiles distinguishing alpha-particle (211)At and (60)Co irradiation. Materials and methods: Gene expression microarray profiling was performed using total RNA from confluent human fibroblasts 5 hours after exposure to (211)At labeled trastuzumab monoclonal antibody (0.25, 0.5, and 1 Gy) and (60)Co (1, 2, and 3 Gy). Results: We report gene expression profiles that distinguish the effect different radiation qualities and absorbed doses have on cellular functions in human fibroblasts. In addition, we identified commonly expressed transcripts between (211)At and (60)Co irradiation. A greater number of transcripts were modulated by (211)At than (60)Co irradiation. In addition, down-regulation was more prevalent than up-regulation following (211)At irradiation. Several biological processes were enriched for both irradiation qualities such as transcription, cell cycle regulation, and cell cycle arrest, whereas mitosis, spindle assembly checkpoint, and apoptotic chromosome condensation were uniquely enriched for alpha particle irradiation. Conclusions: LET-dependent transcriptional modulations were observed in human fibroblasts 5 hours after irradiation exposure. These findings suggest that in comparison with (60)Co, (211)At has the clearest influence on both tumor protein p53-activated and repressed genes, which impose a greater overall burden to the cell following alpha particle irradiation.
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| 6. |
- Elgqvist, Jörgen, 1963, et al.
(författare)
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Ovarian cancer: background and clinical perspectives
- 2010
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Ingår i: Targeted Radionuclide Therapy. - Philadelphia, USA : Lippincott Williams &Wilkins, a Wolter Kluwer business. - 9780781796934 ; , s. 380-396
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 7. |
- Elgqvist, Jörgen, 1963, et al.
(författare)
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Repeated Intraperitoneal alpha-Radioimmunotherapy of Ovarian Cancer in Mice.
- 2010
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Ingår i: Journal of oncology. - : Hindawi Limited. - 1687-8450 .- 1687-8469. ; 2010
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate the therapeutic efficacy of alpha-radioimmunotherapy of ovarian cancer in mice using different fractionated treatment regimens. The study was performed using the monoclonal antibody MX35 F(ab')(2) labeled with the alpha-particle emitter (211)At. Methods. Nude mice were intraperitoneally inoculated with ~1 x 10(7) cells of the cell line NIH:OVCAR-3. Four weeks later 6 groups of animals were given 400 kBq (211)At-MX35 F(ab')(2) as a single or as a repeated treatment of up to 6 times (n = 18 in each group). The fractionated treatments were given every seventh day. Control animals were treated with unlabeled MX35 F(ab')(2) (n = 12). Eight weeks posttreatment the animals were sacrificed and the presence of macro- and microscopic tumors and ascites was determined. Results. The tumor-free fractions (TFFs) of the animals, defined as the fraction of animals with no macro- and microtumors and no ascites, were 0.17, 0.11, 0.39, 0.44, 0.44, and 0.67 when treated with 400 kBq (211)At-MX35 F(ab')(2) once or 2, 3, 4, 5, or 6 times, respectively. Repeated treatment 3 times or more resulted in a significantly higher (P < .05) TFF than compared to treatment once or twice. The presence of ascites decreased from 15 out of 18 animals in the group given only one treatment to zero for the 2 groups given 5 or 6 fractions. Treatment with unlabeled MX35 F(ab')(2) resulted in a TFF of zero. Conclusion. Weekly repeated intraperitoneal injections of tolerable amounts of activity of (211)At-MX35 F(ab')(2) of up to 6 times produced increased therapeutic efficacy without observed toxicity, indicating a potential increase of the therapeutic index.
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| 8. |
- Frost, Sofia, 1981, et al.
(författare)
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Comparison of (211)At-PRIT and (211)At-RIT of Ovarian Microtumors in a Nude Mouse Model.
- 2013
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Ingår i: Cancer biotherapy & radiopharmaceuticals. - : Mary Ann Liebert Inc. - 1557-8852 .- 1084-9785. ; 28:2, s. 108-14
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Tidskriftsartikel (refereegranskat)abstract
- Abstract Purpose: Pretargeted radioimmunotherapy (PRIT) against intraperitoneal (i.p.) ovarian microtumors using avidin-conjugated monoclonal antibody MX35 (avidin-MX35) and (211)At-labeled, biotinylated, succinylated poly-l-lysine ((211)At-B-PL(suc)) was compared with conventional radioimmunotherapy (RIT) using (211)At-labeled MX35 in a nude mouse model. Methods: Mice were inoculated i.p. with 1×10(7) NIH:OVCAR-3 cells. After 3 weeks, they received PRIT (1.0 or 1.5MBq), RIT (0.9MBq), or no treatment. Concurrently, 10 additional animals were sacrificed and examined to determine disease progression at the start of therapy. Treated animals were analyzed with regard to presence of tumors and ascites (tumor-free fraction; TFF), 8 weeks after therapy. Results: Tumor status at baseline was advanced: 70% of sacrificed animals exhibited ascites. The TFFs were 0.35 (PRIT 1.0MBq), 0.45 (PRIT 1.5MBq), and 0.45 (RIT). The 1.5-MBq PRIT group exhibited lower incidence of ascites and fewer tumors >1mm than RIT-treated animals. Conclusions: PRIT was as effective as RIT with regard to TFF; however, the size distribution of tumors and presence of ascites indicated that 1.5-MBq PRIT was more efficient. Despite advanced disease in many animals at the time of treatment, PRIT demonstrated good potential to treat disseminated ovarian cancer.
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| 9. |
- Frost, Sofia, 1981, et al.
(författare)
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In Vivo Distribution of Avidin-Conjugated MX35 and (211)At-Labeled, Biotinylated Poly-l-Lysine for Pretargeted Intraperitoneal ?-Radioimmunotherapy.
- 2011
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Ingår i: Cancer biotherapy & radiopharmaceuticals. - : Mary Ann Liebert Inc. - 1557-8852 .- 1084-9785. ; 26:6
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Tidskriftsartikel (refereegranskat)abstract
- Abstract Purpose: Avidin-coupled monoclonal antibody MX35 (avidin-MX35) and astatine-211?labeled, biotinylated, succinylated poly-l-lysine ((211)At-B-PL(suc)) were administered in mice to assess potential efficacy as an intraperitoneal (i.p.) therapy for microscopic tumors. We aimed to establish a timeline for pretargeted radioimmunotherapy using these substances, and estimate the maximum tolerable activity. Methods: (125)I-avidin-MX35 and (211)At-B-PL(suc) were administered i.p. in nude mice. Tissue distributions were studied at various time points and mean absorbed doses were estimated from organ uptake of (211)At-B-PL(suc). Studies of myelotoxicity were performed after administration of different activities of (211)At-B-PL(suc). Results: We observed low blood content of both (125)I-avidin-MX35 and (211)At-B-PL(suc), indicating fast clearance. After sodium perchlorate blocking, the highest (211)At uptake was found in kidneys. Red bone marrow (RBM) accumulated some (211)At activity. Mean absorbed doses of special interest were 2.3 Gy/MBq for kidneys, 0.4 Gy/MBq for blood, and 0.9 Gy/MBq for RBM. An absorbed dose of 0.9 Gy to the RBM was found to be safe. These values suggested that RBM would be the key dose-limiting organ in the proposed pretargeting scheme, and that blood data alone was not sufficient for predicting its absorbed dose. Conclusions: To attain a favorable distribution of activity and avoid major toxicities, at least 1.0?MBq of (211)At-B-PL(suc) can be administered 24 hours after an i.p. injection of avidin-MX35. These results provide a basis for future i.p. therapy studies in mice of microscopic ovarian cancer.
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| 10. |
- Gustafsson, Anna, et al.
(författare)
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Comparison of therapeutic efficacy and biodistribution of (213)Bi- and (211)At-labeled monoclonal antibody MX35 in an ovarian cancer model.
- 2012
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Ingår i: Nuclear medicine and biology. - : Elsevier BV. - 1872-9614 .- 0969-8051. ; 39:1, s. 15-22
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Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: The purpose of this study was to compare the therapeutic efficacy and biodistribution of the monoclonal antibody MX35 labeled with either (213)Bi or (211)At, both α-emitters, in an ovarian cancer model. METHODS: One hundred female nude BALB/c (nu/nu) mice were inoculated intraperitoneally with human ovarian cancer cells (OVCAR-3). Two weeks later, 40 of these mice were injected intraperitoneally with ∼2.7 MBq of (213)Bi-MX35 (n=20) or ∼0.44 MBq of (211)At-MX35 (n=20). Four weeks after inoculation, 40 new OVCAR-3-inoculated mice were injected with the same activities of (213)Bi-MX35 (n=20) or (211)At-MX35 (n=20). Presence of tumors and ascites was investigated 8 weeks after therapy. Biodistributions of intraperitoneally injected (213)Bi-MX35 and (211)At-MX35 were studied in tumor-free nude BALB/c (nu/nu) mice (n=16). RESULTS: The animals injected with (213)Bi-MX35 or (211)At-MX35 2 weeks after cell inoculation had tumor-free fractions (TFFs) of 0.60 and 0.90, respectively. The untreated reference group had a TFF of 0.20. The groups treated with (213)Bi-MX35 or (211)At-MX35 4 weeks after inoculation both had TFFs of 0.25, and the reference animals all exhibited evidence of disease. The biodistributions of (213)Bi-MX35 and (211)At-MX35 were very similar to each other and displayed no alarming activity levels in the investigated organs. CONCLUSIONS: Micrometastatic growth of an ovarian cancer cell line was reduced in nude mice after treatment with (213)Bi-MX35or (211)At-MX35. Treatment with (211)At-MX35 provided a non-significantly better result for the chosen activity levels. The radiolabeled MX35 did not accumulate to a high extent in the investigated organs. No considerable signs of toxicity were observed.
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| 11. |
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| 12. |
- Högberg, Jonas, 1976, et al.
(författare)
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Bremsstrahlung imaging of 90Y microspheres shows poor resemblance with distributions of 99mTc-MAA in liver
- 2010
-
Ingår i: Journal of the European Society of Therapeutic Radiology and Oncology. - 0167-8140. ; 94:1, s. 25-26
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- PURPOSE To study the resemblance between the distributions of pre- therapeutic 99mTc-MAA and therapeutic 90Y-microspheres, used for ra- dioembolization of liver tumours, making use of gamma- and bremsstrahlung imaging. Furthermore, to establish the accuracy of this method by compar- isons of spatial resolution and radioactivity, performed on line source in water phantom and on resected tumour and normal liver from patients previously treated with 90Y-microspheres. MATERIALS 3 patients diagnosed with liver tumours and planned for surgery; 1 with hepatocellular carcinoma and 2 with cholangiocarcinoma, were treated with SIRTEX R © 90Y-microspheres after standard diagnostic SPECT/CT imag- ing with 99mTc-MAA. The images acquired with gamma camera were com- pared regarding distributions of radioactivity; gamma radiation from the 99mTc-MAA distributions and bremsstrahlung from the distributions of 90Y- microspheres (the latter with a wide bremsstrahlung energy window). Resec- tions of tumour- and some normal liver tissues were performed on all three patients; the resected tissues were sliced, smaller samples were punched out and the radioactivity was measured with a NaI-detector. Furthermore, autoradiography was performed on some slices. A line source with the in- ner diameter 1 mm was positioned in a cylindrical water phantom with the diameter 20 cm; first the line source was filled with 99mTc, then emptied and filled with 90Y. SPECT/CT imaging was performed on both line source se- tups. The spatial resolutions for both radionuclides were then compared. The results from the imaging comparisons performed on the patients were then evaluated with the complementary radiological methods described above. RESULTS The comparison of images from 99mTc-MAA and 90Y showed a considerable deviance in activity distribution for two of the patients. One ex- ample is shown in the figure, the upper image showing 99mTc-MAA and the lower showing 90Y-microspheres. The moderate difference in spatial resolu- tions for 99mTc and 90Y, (15 vs 18 mm FWHM) confirmed the accuracy of these findings. The other radiological methods did also confirm the macro- scopic activity distribution as shown with bremsstrahlung imaging. CONCLUSIONS Bremsstrahlung imaging is a satisfying and reliable method in showing the actual macroscopic distribution of therapeutic 90Y-microspheres used for radioembolization of liver tumours. The results further demonstrate the need for a better diagnostic method than the one currently used, with 99mTc-MAA, thereby providing a better pre-dosimetry; hopefully with a better selection of patients, regarding tumour regression and a lower risk of liver failure.
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| 13. |
- Högberg, Jonas, 1976, et al.
(författare)
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Heterogeneity of microsphere distribution in resected liver and tumour tissue following selective intrahepatic radiotherapy
- 2014
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Ingår i: EJNMMI Research. - : Springer Science and Business Media LLC. - 2191-219X. ; 4:48
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND Selective arterial radioembolisation of liver tumours has increased, because of encouraging efficacy reports; however, therapeutic parameters used in external beam therapy are not applicable for understanding and predicting potential toxicity and efficacy, necessitating further studies of the physical and biological characteristics of radioembolisation. The aim was to characterise heterogeneity in the distribution of microspheres on a therapeutically relevant geometric scale considering the range of yttrium-90 (90Y) β-particles. METHODS Two patients with intrahepatic cholangiocarcinoma, marginally resectable, were treated by selective arterial embolisation with 90Y resin microspheres (SIRTEX®), followed 9 days post-infusion by resection, including macroscopic tumour tissue and surrounding normal liver parenchyma. Formalin-fixed, sectioned resected tissues were exposed to autoradiographic films, or tissue biopsies of various dimensions were punched out for activity measurements and microscopy. RESULTS Autoradiography and activity measurements revealed a higher activity in tumour tissue compared to normal liver parenchyma. Heterogeneity in activity distribution was evident in both normal liver and tumour tissue. Activity measurements were analysed in relation to the sample mass (5 to 422 mg), and heterogeneities were detected by statistical means; the larger the tissue biopsies, the smaller was the coefficient of variation. The skewness of the activity distributions increased with decreasing biopsy mass. CONCLUSIONS The tissue activity distributions in normal tissue were heterogeneous on a relevant geometric scale considering the range of the ionising electrons. Given the similar and repetitive structure of the liver parenchyma, this finding could partly explain the tolerance of a relatively high mean absorbed dose to the liver parenchyma from β-particles. Keywords: Radioembolisation; Y-90; SIR; Surgery; Activity heterogeneity
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| 14. |
- Högberg, Jonas, 1976, et al.
(författare)
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On the dose heterogeneity in normal liver tissue due to treatment of liver tumors with yttrium-90 microspheres
- 2012
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Ingår i: 25th Annual Congress on European Association of Nuclear Medicine, Milano, Italy, October 27-31, 2012. European Journal of Nuclear Medicine and Molecular Imaging. - : Springer Science and Business Media LLC. - 1619-7070 .- 1619-7089. ; 39:suppl 2
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Aim: When treating patients with primary or metastatic liver cancer, applying external radiotherapy, an absorbed dose of 30 - 35 Gy to the whole normal liver tissue volume is associated with a 5 % risk of radiation-induced hepatitis. If less than half of the normal liver volume is being exposed, the threshold for a 5 % risk of hepatitis is increased to above 60 Gy for both primary and metastatic liver cancer. Experience with patients treated with SIR-Spheres® (Sirtex Medical Ltd.), resin microspheres aggregated with yttrium-90, has shown that most patients tolerate an average absorbed dose to normal liver tissue higher than 60 Gy. The high tolerance for this treatment procedure can probably be explained by the resulting heterogenic distribution of radioactivity. It is of interest to study the degree of heterogeneity in the distribution of radioactivity in normal liver tissue, in order to explain or even predict the tolerance to radiation. The aim of this study was to describe the degree of heterogeneity by comparing the relative standard deviations of the radioactivity concentration for different sample mass categories. Materials and Methods: Two patients with cholangiocarcinoma were planned for a combined treatment with yttrium-90-aggregated SIR-Spheres followed by surgery 9 days after radiotherapy. According to standard protocol for treatments with SIR-Spheres, the therapies were preceded by Tc-99m-labled Macro aggregated albumin (Tc-99m-MAA) distribution studies for pre-therapeutic dosimetry and lung shunting evaluations. After surgery the resected tissue, containing both tumour and normal tissue, was studied regarding the distribution of radioactivity. Several small circular samples of normal liver tissue were punched out from 2 mm thick slices of resected tissue, deliberately varying the sizes, and thus the masses of the tissue samples (from 6 to 102 mg). The samples were weighed and categorized in two (first patient) and three (second patient) groups, depending on sample mass. After this the radioactivity was measured with a NaI(Tl) detector. The relative standard deviations (SD/Median) for the radioactivity concentration for each sample mass group were determined and compared. Results: The relative standard deviation for the radioactivity concentration was decreasing rapidly with increasing sample mass. Conclusion: The results indicate a considerable degree of heterogeneity in the distribution of microspheres. One probable explanation for this heterogeneity is clustering of microspheres in the blood vessels.
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| 15. |
- Högberg, Jonas, 1976, et al.
(författare)
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Radiation exposure during liver surgery after treatment with (90)Y microspheres, evaluated with computer simulations and dosimeter measurements.
- 2012
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Ingår i: Journal of radiological protection : official journal of the Society for Radiological Protection. - : IOP Publishing. - 1361-6498. ; 32:4, s. 439-46
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Tidskriftsartikel (refereegranskat)abstract
- Purpose. Two patients with liver tumours were planned for a combined treatment, including surgery with preceding injections of β(-) radiation emitting (90)Y microspheres (SIRTEX(®)). The aim of this paper is to present a method of pre-surgical computer simulations of the absorbed dose rate on the surface of tumour tissue, combined with measurements of the actual absorbed dose rate on resected tissue, in order to estimate the absorbed dose to a surgeon's fingers during such surgery procedures. Methods and Materials. The dose rates from β(-) radiation on the surface of tumour tissue were simulated with the software VARSKIN(®)Mod2. The activity concentrations in tumours were estimated, based on SPECT/CT distribution studies of (99m)Tc-MAA and confirmed by SPECT/CT bremsstrahlung studies of (90)Y microspheres. The activity distributions were considered as homogeneous within the tumour regions. The absorbed dose rates at different tumour tissue spots were calculated based on measurements with thermo-luminescent dosimeters (TLD) fastened on resected tissue. Results. The simulations showed a good agreement with the averaged absorbed dose rates based on TLD measurements performed on resected tissue, differing by 13% and 4% respectively. The absorbed dose rates at the measured maximum hotspots were twice as high as the average dose rates for both patients. Conclusion. The data is not sufficient in order to draw any general conclusions about dose rates on tumour tissue during similar surgeries, neither about the influence of dose rate heterogeneities nor about average dose rates. However, the agreement between simulations and measurements on these limited data indicate that this approach is a promising method for estimations of the radiation exposure to the surgeons' fingers during this kind of surgery procedure. More data from similar surgeries are necessary in order to validate the method.
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| 16. |
- Johansson, Pegah, 1978, et al.
(författare)
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In-solution staining and arraying method for the immunofluorescence detection of γH2AX foci optimized for clinical applications.
- 2011
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Ingår i: BioTechniques. - : Future Science Ltd. - 1940-9818 .- 0736-6205. ; 51:3, s. 185-9
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Tidskriftsartikel (refereegranskat)abstract
- Immunofluorescence quantification of γH2AX foci is a powerful approach to quantify DNA double-strand breaks induced by cancer therapy or accidental exposure to ionizing radiation. Here we report a modification to the γH2AX immunofluorescence labeling method, whereby cells are stained in-solution before being spotted and fixed onto microscope slides. Our modified method allows arraying of 16 patient samples/slide ready for foci counting in 2 h and demonstrated reliably detection of γH2AX foci in mononuclear cells prepared from patients who had undergone radiation therapy.
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| 17. |
- Magnander, Karin, 1979, et al.
(författare)
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Clustered DNA damage in irradiated human diploid fibroblasts: influence of chromatin organization.
- 2010
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Ingår i: Radiation research. - 1938-5404. ; 173:3, s. 272-82
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Tidskriftsartikel (refereegranskat)abstract
- Clustered DNA damages are induced by ionizing radiation and are defined as two or more lesions within one or two helical turns. The aim of this study was to investigate the induction and repair of clustered DNA damage in cells with emphasis on the influence of structural differences in the chromatin organization. Human fibroblasts were irradiated with X rays and induced DSBs and clustered damages were quantified using pulsed-field gel electrophoresis combined with postirradiation incubation with the base excision repair endonuclease Fpg, which recognizes oxidized purines and cleaves the strand at sites inducing strand breaks. Hence clustered damages appear in enzyme-treated samples as additional DSBs. The chromatin was modified by different pretreatments that resulted in structures with varying compactness and levels of free radical scavenging capacity. We found that the induction of DSBs and clustered damages increased linearly with dose in all structures and that both types of lesions were allocated randomly within the nucleus. The induction yields increased with decreasing compactness of chromatin, and the chromatin effect was larger for clustered lesions than for DSBs. Clustered damages were processed efficiently with a fast and a slow repair component similar to that for induced DSBs.
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| 18. |
- Mehrara, Esmaeil, 1971, et al.
(författare)
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A new method to estimate parameters of the growth model for metastatic tumours.
- 2013
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Ingår i: Theoretical biology & medical modelling. - : Springer Science and Business Media LLC. - 1742-4682. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: Knowledge of natural tumour growth is valuable for understanding tumour biology, optimising screening programs, prognostication, optimal scheduling of chemotherapy, and assessing tumour spread. However, mathematical modelling in individuals is hampered by the limited data available. We aimed to develop a method to estimate parameters of the growth model and formation rate of metastases in individual patients. MATERIALS AND METHODS: Data from one patient with liver metastases from a primary ileum carcinoid and one patient with lung metastases from a primary renal cell carcinoma were used to demonstrate this new method. Metastatic growth models were estimated by direct curve fitting, as well as with the new proposed method based on the relationship between tumour growth rate and tumour volume. The new model was derived from the Gompertzian growth model by eliminating the time factor (age of metastases), which made it possible to perform the calculations using data from all metastases in each patient. Finally, the formation time of each metastasis and, consecutively, the formation rate of metastases in each patient were estimated. RESULTS: With limited measurements in clinical studies, fitting different growth curves was insufficient to estimate true tumour growth, even if patients were followed for several years. Growth of liver metastases was well described with a general growth model for all metastases. However, the lung metastases from renal cell carcinoma were better described by heterogeneous exponential growth with various growth rates. CONCLUSION: Analysis of the regression of tumour growth rate with the logarithm of tumour volume can be used to estimate parameters of the tumour growth model and metastasis formation rates, and therefore the number and size distribution of metastases in individuals.
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