Radiation safety of the sentinel lymph node technique in breast cancer

Many publications attest to the potential of the sentinel lymph node technique in advancing the clinical management of melanoma and, more recently, breast cancer. Whilst not yet universally regarded as the standard of care, the technique is gaining wide acceptance. Use of a radiolabelled colloidal tracer is central to optimising sensitivity, and this brings with it the need to address radiation safety issues relating to the use of radioactive materials in the operating theatre and pathology laboratory, and the generation of radioactive waste. The radiation dose to the patient should also be determined if the professional is to reassure the patient by placing this in its proper context. For the purpose of this investigation, biodistribution data were obtained from patient studies to quantify the migration of tracer beyond the injection site, thereby permitting a detailed assessment of the internal dosimetry of the tracer and the resulting radiation dose to the patient. Uptake of tracer in the sentinel nodes, reticulo-endothelial system and circulating blood was investigated. The radiation dose to surgical staff was recorded using whole-body monitors and extremity dosimeters worn at the fingers. Clinical waste in the operating theatre was monitored and the radioactive content of significantly contaminated items determined. The radiation dose to pathology staff was estimated from knowledge of the radioactive content of the specimens obtained and a study of work practices. Migration of tracer was found to be minimal, with greater than 95% retention at the injection site. The effective dose resulting to the patient was 2.1×10^–2 mSv/MBq, with a mean breast dose of 7.2×10^–1 mGy/MBq. A mean whole-body dose of 0.34 μSv was received by surgical staff per procedure, with a mean finger dose of 0.09 mSv (90 μSv). Radiation doses received by pathology staff will be predominantly below measurable levels and are likely to be negligible unless primary specimens from a large number of studies are analysed promptly upon their excision. At operation, surgical swabs can become significantly contaminated and have been found to contain up to 22% of the administered activity, dependent upon the surgical procedure performed. It is concluded that moderate activities of technetium-99m labelled tracer are administered to the patient, and the radiation risk to the patient is consequently low relative to that from many other medical exposures. The radiation doses to staff groups involved in all aspects of the technique are low, and under normal circumstances and levels of workload, routine radiation monitoring will not be required. Standard biohazard precautions prevent direct intake of radioactive contamination. Radioactive waste is created in the operating theatre, and may be generated in the pathology laboratory if specimens are not routinely stored until fully decayed. This will require special handling if the disposal of radioactive material is not permitted. Received 4 November and in revised form 14 December 1999     

Magnetic resonance diffusion-perfusion mismatch in acute ischemic stroke: An update

The concept of magnetic resonance perfusion-diffusion mismatch(PDM) provides a practical and approximate measure of the tissue at risk and has been increasingly applied for the evaluation of hyperacute and acute stroke in animals and patients.Recent studies demonstrated that PDM does not optimally define the ischemic penumbra;because early abnormality on diffusion-weighted imaging overestimates the infarct core by including part of the penumbra,and the abnormality on perfusion weighted imaging overestimates the penumbra by including regions of benign oligemia.To overcome these limitations,many efforts have been made to optimize conventional PDM.Various alternatives beyond the PDM concept are under investigation in order to better define the penumbra.The PDM theory has been applied in ischemic stroke for at least three purposes:to be used as a practical selection tool for stroke treatment;to test the hypothesis that patients with PDM pattern will benefit from treatment,while those without mismatch pattern will not;to be a surrogate measure for stroke outcome.The main patterns of PDM and its relation with clinical outcomes were also briefly reviewed.The conclusion was that patients with PDM documented more reperfusion,reduced infarct growth and better clinical outcomes compared to patients without PDM,but it was not yet clear that thrombolytic therapy is beneficial when patients were selected on PDM.Studies based on a larger cohort are currently under investigation to further validate the PDM hypothesis.     

双探头符合线路SPECT正电子显像衰减校正实验研究

Objective The photons from the body would be attenuated in their intensity by the soft tissue before they reach the detectors. Some of them lost more intensity than others when coming from the deeper body. Attenuation of the photons would distort the image, affect the image quality, and may lead to misdiagnosis. In this research the X-ray and γ-ray were used as transmission resources for accurate assess-ment of attenuation in each part of the body. The transmission data was used to correct the emission data from the body. Iteration algorithm was used for the reconstruction of attenuation corrected tomography ima-ges. Evaluate the efficacy of attenuation correction in duel head hybrid SPECT/coincidence PET systems (SPECT/PET) and SPECT using both the Jaszczak and the myocardial phantoms. Methods For PET phantom study, the Jaszczak phantom was filled with the aqueous solution of 18F-fluorodeoxyglucose (FDG) and was scanned with two hybrid SPECT/coincidence PET systems respectively (Vertex Plus, Netherlands Philips ADAC Company and Hawkeye, USA GE Company). The PET images were acquired and reconstruc-ted. Results The "cold" lesion, which the diameter was less than 12 mm of uncorrected image, could not be identified. But it, after correction, diameter 9 mm, would be recognized clearly, less than 7 mm would not be distinguished. Noncorrected image could only identify "hot" lesions which the diameter were 9, 12, 14, 18, 22 and 38 mm, while in the corrected image, not only it was much better, but also the "hot" le-sion of 6 mm was distinguished. In Hawkeye, the same situation, the corrected image of was improved obvi-ously; the disparity of counts between surrounding and deep center less, and the counts in deep center were compensated. There were only 3 round " cold" lesions could be recognized, the diameter: 14, 18 and 20 mm; all of them which diameter were less than 12 mm could not be distinguished. One in the center was al-most as background, and could not be identified. The radioactive accounts of surrounding and center were quite different. The corrected image 5 "cold" lesions could be found, 9, 12, 14, 18 and 20 mm, but7 mm could not be found. The noncorrected image, only 12, 14, 18, 22 and 38 mm " hot" lesions could be found, and by the surrounding, there was an arc shape "hot" lesion. But it could distinguish 9, 12, 14, 18, 22 and 38 mm "hot" lesions on the corrected image, and the image was much better than noncorrected one. Conclusions The corrected image of Vertex Plus was improved obviously with the disparity of counts between surrounding and deep center less, and the counts in deep center was compensated. The result of at-tenuation with phantom showed that 137Cs was better than CT in both image quality and spatial resolution.     

双探头符合线路SPECT正电子显像衰减校正实验研究

Objective The photons from the body would be attenuated in their intensity by the soft tissue before they reach the detectors. Some of them lost more intensity than others when coming from the deeper body. Attenuation of the photons would distort the image, affect the image quality, and may lead to misdiagnosis. In this research the X-ray and γ-ray were used as transmission resources for accurate assess-ment of attenuation in each part of the body. The transmission data was used to correct the emission data from the body. Iteration algorithm was used for the reconstruction of attenuation corrected tomography ima-ges. Evaluate the efficacy of attenuation correction in duel head hybrid SPECT/coincidence PET systems (SPECT/PET) and SPECT using both the Jaszczak and the myocardial phantoms. Methods For PET phantom study, the Jaszczak phantom was filled with the aqueous solution of 18F-fluorodeoxyglucose (FDG) and was scanned with two hybrid SPECT/coincidence PET systems respectively (Vertex Plus, Netherlands Philips ADAC Company and Hawkeye, USA GE Company). The PET images were acquired and reconstruc-ted. Results The "cold" lesion, which the diameter was less than 12 mm of uncorrected image, could not be identified. But it, after correction, diameter 9 mm, would be recognized clearly, less than 7 mm would not be distinguished. Noncorrected image could only identify "hot" lesions which the diameter were 9, 12, 14, 18, 22 and 38 mm, while in the corrected image, not only it was much better, but also the "hot" le-sion of 6 mm was distinguished. In Hawkeye, the same situation, the corrected image of was improved obvi-ously; the disparity of counts between surrounding and deep center less, and the counts in deep center were compensated. There were only 3 round " cold" lesions could be recognized, the diameter: 14, 18 and 20 mm; all of them which diameter were less than 12 mm could not be distinguished. One in the center was al-most as background, and could not be identified. The radioactive accounts of surrounding and center were quite different. The corrected image 5 "cold" lesions could be found, 9, 12, 14, 18 and 20 mm, but7 mm could not be found. The noncorrected image, only 12, 14, 18, 22 and 38 mm " hot" lesions could be found, and by the surrounding, there was an arc shape "hot" lesion. But it could distinguish 9, 12, 14, 18, 22 and 38 mm "hot" lesions on the corrected image, and the image was much better than noncorrected one. Conclusions The corrected image of Vertex Plus was improved obviously with the disparity of counts between surrounding and deep center less, and the counts in deep center was compensated. The result of at-tenuation with phantom showed that 137Cs was better than CT in both image quality and spatial resolution.     

双探头符合线路SPECT正电子显像衰减校正实验研究

Objective The photons from the body would be attenuated in their intensity by the soft tissue before they reach the detectors. Some of them lost more intensity than others when coming from the deeper body. Attenuation of the photons would distort the image, affect the image quality, and may lead to misdiagnosis. In this research the X-ray and γ-ray were used as transmission resources for accurate assess-ment of attenuation in each part of the body. The transmission data was used to correct the emission data from the body. Iteration algorithm was used for the reconstruction of attenuation corrected tomography ima-ges. Evaluate the efficacy of attenuation correction in duel head hybrid SPECT/coincidence PET systems (SPECT/PET) and SPECT using both the Jaszczak and the myocardial phantoms. Methods For PET phantom study, the Jaszczak phantom was filled with the aqueous solution of 18F-fluorodeoxyglucose (FDG) and was scanned with two hybrid SPECT/coincidence PET systems respectively (Vertex Plus, Netherlands Philips ADAC Company and Hawkeye, USA GE Company). The PET images were acquired and reconstruc-ted. Results The "cold" lesion, which the diameter was less than 12 mm of uncorrected image, could not be identified. But it, after correction, diameter 9 mm, would be recognized clearly, less than 7 mm would not be distinguished. Noncorrected image could only identify "hot" lesions which the diameter were 9, 12, 14, 18, 22 and 38 mm, while in the corrected image, not only it was much better, but also the "hot" le-sion of 6 mm was distinguished. In Hawkeye, the same situation, the corrected image of was improved obvi-ously; the disparity of counts between surrounding and deep center less, and the counts in deep center were compensated. There were only 3 round " cold" lesions could be recognized, the diameter: 14, 18 and 20 mm; all of them which diameter were less than 12 mm could not be distinguished. One in the center was al-most as background, and could not be identified. The radioactive accounts of surrounding and center were quite different. The corrected image 5 "cold" lesions could be found, 9, 12, 14, 18 and 20 mm, but7 mm could not be found. The noncorrected image, only 12, 14, 18, 22 and 38 mm " hot" lesions could be found, and by the surrounding, there was an arc shape "hot" lesion. But it could distinguish 9, 12, 14, 18, 22 and 38 mm "hot" lesions on the corrected image, and the image was much better than noncorrected one. Conclusions The corrected image of Vertex Plus was improved obviously with the disparity of counts between surrounding and deep center less, and the counts in deep center was compensated. The result of at-tenuation with phantom showed that 137Cs was better than CT in both image quality and spatial resolution.     

双探头符合线路SPECT正电子显像衰减校正实验研究

Objective The photons from the body would be attenuated in their intensity by the soft tissue before they reach the detectors. Some of them lost more intensity than others when coming from the deeper body. Attenuation of the photons would distort the image, affect the image quality, and may lead to misdiagnosis. In this research the X-ray and γ-ray were used as transmission resources for accurate assess-ment of attenuation in each part of the body. The transmission data was used to correct the emission data from the body. Iteration algorithm was used for the reconstruction of attenuation corrected tomography ima-ges. Evaluate the efficacy of attenuation correction in duel head hybrid SPECT/coincidence PET systems (SPECT/PET) and SPECT using both the Jaszczak and the myocardial phantoms. Methods For PET phantom study, the Jaszczak phantom was filled with the aqueous solution of 18F-fluorodeoxyglucose (FDG) and was scanned with two hybrid SPECT/coincidence PET systems respectively (Vertex Plus, Netherlands Philips ADAC Company and Hawkeye, USA GE Company). The PET images were acquired and reconstruc-ted. Results The "cold" lesion, which the diameter was less than 12 mm of uncorrected image, could not be identified. But it, after correction, diameter 9 mm, would be recognized clearly, less than 7 mm would not be distinguished. Noncorrected image could only identify "hot" lesions which the diameter were 9, 12, 14, 18, 22 and 38 mm, while in the corrected image, not only it was much better, but also the "hot" le-sion of 6 mm was distinguished. In Hawkeye, the same situation, the corrected image of was improved obvi-ously; the disparity of counts between surrounding and deep center less, and the counts in deep center were compensated. There were only 3 round " cold" lesions could be recognized, the diameter: 14, 18 and 20 mm; all of them which diameter were less than 12 mm could not be distinguished. One in the center was al-most as background, and could not be identified. The radioactive accounts of surrounding and center were quite different. The corrected image 5 "cold" lesions could be found, 9, 12, 14, 18 and 20 mm, but7 mm could not be found. The noncorrected image, only 12, 14, 18, 22 and 38 mm " hot" lesions could be found, and by the surrounding, there was an arc shape "hot" lesion. But it could distinguish 9, 12, 14, 18, 22 and 38 mm "hot" lesions on the corrected image, and the image was much better than noncorrected one. Conclusions The corrected image of Vertex Plus was improved obviously with the disparity of counts between surrounding and deep center less, and the counts in deep center was compensated. The result of at-tenuation with phantom showed that 137Cs was better than CT in both image quality and spatial resolution.     

双探头符合线路SPECT正电子显像衰减校正实验研究

Objective The photons from the body would be attenuated in their intensity by the soft tissue before they reach the detectors. Some of them lost more intensity than others when coming from the deeper body. Attenuation of the photons would distort the image, affect the image quality, and may lead to misdiagnosis. In this research the X-ray and γ-ray were used as transmission resources for accurate assess-ment of attenuation in each part of the body. The transmission data was used to correct the emission data from the body. Iteration algorithm was used for the reconstruction of attenuation corrected tomography ima-ges. Evaluate the efficacy of attenuation correction in duel head hybrid SPECT/coincidence PET systems (SPECT/PET) and SPECT using both the Jaszczak and the myocardial phantoms. Methods For PET phantom study, the Jaszczak phantom was filled with the aqueous solution of 18F-fluorodeoxyglucose (FDG) and was scanned with two hybrid SPECT/coincidence PET systems respectively (Vertex Plus, Netherlands Philips ADAC Company and Hawkeye, USA GE Company). The PET images were acquired and reconstruc-ted. Results The "cold" lesion, which the diameter was less than 12 mm of uncorrected image, could not be identified. But it, after correction, diameter 9 mm, would be recognized clearly, less than 7 mm would not be distinguished. Noncorrected image could only identify "hot" lesions which the diameter were 9, 12, 14, 18, 22 and 38 mm, while in the corrected image, not only it was much better, but also the "hot" le-sion of 6 mm was distinguished. In Hawkeye, the same situation, the corrected image of was improved obvi-ously; the disparity of counts between surrounding and deep center less, and the counts in deep center were compensated. There were only 3 round " cold" lesions could be recognized, the diameter: 14, 18 and 20 mm; all of them which diameter were less than 12 mm could not be distinguished. One in the center was al-most as background, and could not be identified. The radioactive accounts of surrounding and center were quite different. The corrected image 5 "cold" lesions could be found, 9, 12, 14, 18 and 20 mm, but7 mm could not be found. The noncorrected image, only 12, 14, 18, 22 and 38 mm " hot" lesions could be found, and by the surrounding, there was an arc shape "hot" lesion. But it could distinguish 9, 12, 14, 18, 22 and 38 mm "hot" lesions on the corrected image, and the image was much better than noncorrected one. Conclusions The corrected image of Vertex Plus was improved obviously with the disparity of counts between surrounding and deep center less, and the counts in deep center was compensated. The result of at-tenuation with phantom showed that 137Cs was better than CT in both image quality and spatial resolution.     

双探头符合线路SPECT正电子显像衰减校正实验研究

Objective The photons from the body would be attenuated in their intensity by the soft tissue before they reach the detectors. Some of them lost more intensity than others when coming from the deeper body. Attenuation of the photons would distort the image, affect the image quality, and may lead to misdiagnosis. In this research the X-ray and γ-ray were used as transmission resources for accurate assess-ment of attenuation in each part of the body. The transmission data was used to correct the emission data from the body. Iteration algorithm was used for the reconstruction of attenuation corrected tomography ima-ges. Evaluate the efficacy of attenuation correction in duel head hybrid SPECT/coincidence PET systems (SPECT/PET) and SPECT using both the Jaszczak and the myocardial phantoms. Methods For PET phantom study, the Jaszczak phantom was filled with the aqueous solution of 18F-fluorodeoxyglucose (FDG) and was scanned with two hybrid SPECT/coincidence PET systems respectively (Vertex Plus, Netherlands Philips ADAC Company and Hawkeye, USA GE Company). The PET images were acquired and reconstruc-ted. Results The "cold" lesion, which the diameter was less than 12 mm of uncorrected image, could not be identified. But it, after correction, diameter 9 mm, would be recognized clearly, less than 7 mm would not be distinguished. Noncorrected image could only identify "hot" lesions which the diameter were 9, 12, 14, 18, 22 and 38 mm, while in the corrected image, not only it was much better, but also the "hot" le-sion of 6 mm was distinguished. In Hawkeye, the same situation, the corrected image of was improved obvi-ously; the disparity of counts between surrounding and deep center less, and the counts in deep center were compensated. There were only 3 round " cold" lesions could be recognized, the diameter: 14, 18 and 20 mm; all of them which diameter were less than 12 mm could not be distinguished. One in the center was al-most as background, and could not be identified. The radioactive accounts of surrounding and center were quite different. The corrected image 5 "cold" lesions could be found, 9, 12, 14, 18 and 20 mm, but7 mm could not be found. The noncorrected image, only 12, 14, 18, 22 and 38 mm " hot" lesions could be found, and by the surrounding, there was an arc shape "hot" lesion. But it could distinguish 9, 12, 14, 18, 22 and 38 mm "hot" lesions on the corrected image, and the image was much better than noncorrected one. Conclusions The corrected image of Vertex Plus was improved obviously with the disparity of counts between surrounding and deep center less, and the counts in deep center was compensated. The result of at-tenuation with phantom showed that 137Cs was better than CT in both image quality and spatial resolution.     

双探头符合线路SPECT正电子显像衰减校正实验研究

Objective The photons from the body would be attenuated in their intensity by the soft tissue before they reach the detectors. Some of them lost more intensity than others when coming from the deeper body. Attenuation of the photons would distort the image, affect the image quality, and may lead to misdiagnosis. In this research the X-ray and γ-ray were used as transmission resources for accurate assess-ment of attenuation in each part of the body. The transmission data was used to correct the emission data from the body. Iteration algorithm was used for the reconstruction of attenuation corrected tomography ima-ges. Evaluate the efficacy of attenuation correction in duel head hybrid SPECT/coincidence PET systems (SPECT/PET) and SPECT using both the Jaszczak and the myocardial phantoms. Methods For PET phantom study, the Jaszczak phantom was filled with the aqueous solution of 18F-fluorodeoxyglucose (FDG) and was scanned with two hybrid SPECT/coincidence PET systems respectively (Vertex Plus, Netherlands Philips ADAC Company and Hawkeye, USA GE Company). The PET images were acquired and reconstruc-ted. Results The "cold" lesion, which the diameter was less than 12 mm of uncorrected image, could not be identified. But it, after correction, diameter 9 mm, would be recognized clearly, less than 7 mm would not be distinguished. Noncorrected image could only identify "hot" lesions which the diameter were 9, 12, 14, 18, 22 and 38 mm, while in the corrected image, not only it was much better, but also the "hot" le-sion of 6 mm was distinguished. In Hawkeye, the same situation, the corrected image of was improved obvi-ously; the disparity of counts between surrounding and deep center less, and the counts in deep center were compensated. There were only 3 round " cold" lesions could be recognized, the diameter: 14, 18 and 20 mm; all of them which diameter were less than 12 mm could not be distinguished. One in the center was al-most as background, and could not be identified. The radioactive accounts of surrounding and center were quite different. The corrected image 5 "cold" lesions could be found, 9, 12, 14, 18 and 20 mm, but7 mm could not be found. The noncorrected image, only 12, 14, 18, 22 and 38 mm " hot" lesions could be found, and by the surrounding, there was an arc shape "hot" lesion. But it could distinguish 9, 12, 14, 18, 22 and 38 mm "hot" lesions on the corrected image, and the image was much better than noncorrected one. Conclusions The corrected image of Vertex Plus was improved obviously with the disparity of counts between surrounding and deep center less, and the counts in deep center was compensated. The result of at-tenuation with phantom showed that 137Cs was better than CT in both image quality and spatial resolution.     

双探头符合线路SPECT正电子显像衰减校正实验研究

Objective The photons from the body would be attenuated in their intensity by the soft tissue before they reach the detectors. Some of them lost more intensity than others when coming from the deeper body. Attenuation of the photons would distort the image, affect the image quality, and may lead to misdiagnosis. In this research the X-ray and γ-ray were used as transmission resources for accurate assess-ment of attenuation in each part of the body. The transmission data was used to correct the emission data from the body. Iteration algorithm was used for the reconstruction of attenuation corrected tomography ima-ges. Evaluate the efficacy of attenuation correction in duel head hybrid SPECT/coincidence PET systems (SPECT/PET) and SPECT using both the Jaszczak and the myocardial phantoms. Methods For PET phantom study, the Jaszczak phantom was filled with the aqueous solution of 18F-fluorodeoxyglucose (FDG) and was scanned with two hybrid SPECT/coincidence PET systems respectively (Vertex Plus, Netherlands Philips ADAC Company and Hawkeye, USA GE Company). The PET images were acquired and reconstruc-ted. Results The "cold" lesion, which the diameter was less than 12 mm of uncorrected image, could not be identified. But it, after correction, diameter 9 mm, would be recognized clearly, less than 7 mm would not be distinguished. Noncorrected image could only identify "hot" lesions which the diameter were 9, 12, 14, 18, 22 and 38 mm, while in the corrected image, not only it was much better, but also the "hot" le-sion of 6 mm was distinguished. In Hawkeye, the same situation, the corrected image of was improved obvi-ously; the disparity of counts between surrounding and deep center less, and the counts in deep center were compensated. There were only 3 round " cold" lesions could be recognized, the diameter: 14, 18 and 20 mm; all of them which diameter were less than 12 mm could not be distinguished. One in the center was al-most as background, and could not be identified. The radioactive accounts of surrounding and center were quite different. The corrected image 5 "cold" lesions could be found, 9, 12, 14, 18 and 20 mm, but7 mm could not be found. The noncorrected image, only 12, 14, 18, 22 and 38 mm " hot" lesions could be found, and by the surrounding, there was an arc shape "hot" lesion. But it could distinguish 9, 12, 14, 18, 22 and 38 mm "hot" lesions on the corrected image, and the image was much better than noncorrected one. Conclusions The corrected image of Vertex Plus was improved obviously with the disparity of counts between surrounding and deep center less, and the counts in deep center was compensated. The result of at-tenuation with phantom showed that 137Cs was better than CT in both image quality and spatial resolution.