APPARATUS FOR PROSTATE CANCER DIAGNOSE

Abstract: X-ray fluorescence is used for in vivo determining elements in prostate cancer. One preferred application is in determining level of Zn in prostate as means for diagnosing prostate cancer or staging the disease.

Description: APPARATUS FOR PROSTATE CANCER DIAGNOSE FIELD OF THE INVENTION The present invention is directed to an apparatus and method for detection of chemical elements in the prostate using the X-ray fluorescence method and, particularly, to an apparatus and method for detection and staging of prostate cancer by in vivo determination and mapping of Zn in the prostate. PRIOR ART In order to describe the state of the art in the field of the invention, mention of the following references will be made: 1. Catalona, W. J., Clinical utility of measurements of free and total prostate- specific antigen (PSA): A review, Prostate 7:64, (1996). 2. Catalona, W.J., Partin, A.W., Finlay, J.A., eChan, D.W., Rittenhouse, HJG., Wolfert, R.L., and Woodrum, D.L., Use of percentage of free prostate specific antigen to identify men at high risk of prostate cancer when PSA levels are 2.51 to 4 ng/ml and digital examination is not suspicious for prostate cancer: An alternative model, Urology, 54:220-224, (1999). 3. Cotran R.S., Kumar V. and Collins T., Robbins Pathologic Basis of Disease, W.B. Sounders Co., Sixth Edition, 1029, (1999). 4. Gyorkey, R, Min K.W., Huff, J.A. and Gyorkey, P., Zinc and magnesium in human prostate gland: normal hyperplastic and neoplastic, Cancer, 27:1348, (1967). 5. Lahtonen, R., Zinc and cadmium concentrations in whole tissue and separated epithelium and stroma from human benign prostatic hypertrophic glands. Prostate, 6:177, (1985). 6. Gonic, P., Oberleas D., Knechtges T. and Prasad, A.S., aAtomic absorption determination of zinc in the prostate. Invest. Urol, 6:345, (1969). 7. Dhar, N.K., Goel, T.C., Dube, PC, Chowdury, A.R. and Kar, A.B., Distribution and concentration of zinc in the subcellular fractions of benign hyperplastic and malignant neoplastic human prostate, Exp. Mol. Pathol, 19:139, (1973). 8. Habib, F.K., Mason, M.K., Smith, PH., and Stitch, S.R., Cancer of the prostate: early diagnosis by zinc and hormone analysis, Br. J. Cancer 39:700, (1979). 9. Ogunlewe, J.O. and Osegbe, D.N., Zinc and cadmium concentrations in indigenous blacks with normal, hypertrophic and malignant prostate, Cancer, 63:1388, (1989). 10. Feustel, A., Wennrich, R., Steiniger, D. and Klauss, P., Zinc and cadmium concentration in prostatic carcinoma of different histological grading in comparison to normal prostate tissue and adenofibromyomatosis (BPH), Urol. Res. 10:301, 1982). 11. Zaichick, V.Y, Sviridova, T.V. and Zaichick, S.V., Zinc in the human prostate gland, normal, hyperplastic and cancerous, Int. Urol. Nephrol., 29:687-694, (1997). BACKGROUND OF THE INVENTION Carcinoma of the prostate is the most common form of cancer in men. The methods commonly used today for detection of prostate cancer are digital rectal examination (DRE), transrectal ultrasound (TRUS) and prostate-specific-antigen (PSA) determination. There are large uncertainties in each one of them. Therefore, the diagnosis is often based on a combination of these examinations. PSA testing is the most common assay used in diagnosis of prostate cancer and particularly in screening. In normal men, only minute amounts of PSA circulate in the serum. Elevated PSA levels in blood occur in association with localized as well as advanced prostate cancer. In most laboratories a serum level of 4 ng/ml is used as a cut-off point between normal and abnormal. However, elevations in PSA occur not only in cancer cases but also in some non-neoplastic conditions, such as nodular hyperplasia and prostatitis. There is a considerable overlap in levels of serum PSA between that found in such conditions and that found in prostate cancer patients. For instance, 25 to 30% of men with nodular hyperplasia and 80% with histologically documented cancer have PSA serum level greater than 4 ng/ml. In view of this large overlap, several refinements in the estimation and interpretation of PSA values have been proposed, such as PSA density (ratio of PSA level to the volume of the prostate gland), PSA velocity (rate of change in the PSA level over time), age-specific reference values and the ratio of free and total PSA in the serum (percent free free PSA; %FPSA). Although it appears that %FPSA is valuable in discriminating between benign and malignant disease for cases where the total PSA is in the "gray zone" of 4 to 10 ng/ml, until the value of the above mentioned refinements is better established, serum PSA by itself cannot be used for detection of early cancer and must be combined with other diagnostic indicators. In addition to the above mentionedabove-mentioned deficiencies, the existing methods do not provide sufficient information about the stage of the disease, namely the tumor dimension and the level of cancer proliferation. Moreover, when cancer is suspected a biopsy procedure is usually performed. The lack of precise information as to the tumor localization renders the biopsy procedure inefficient. It is well established that a normal human prostate gland contains high levels of zinc (Zn). Although reported values vary considerably, whole prostate preparations contain Zn concentrations of about 150 μg/g wet weight, which is about 2-5 times greater than Zn content of most other tissues. Zinc is not uniformly distributed throughout the prostate and, as dcmonstateddemonstrated by Gyorkey et al, 1967, the highest Zn content (211 μ/g wet weight) is found in the lateral lobe of the peripheral zone. Numerous in vitro studies (Gyorkey et al. 1967, Lahtonen, 1985, Gonic et al, 1969, Dhar et al, 1973; Habib et al, 1979; Ogunlewe and Osegbe, 1989; Feustel et al, 1982; and Zaichick et al, 1997) indicate that Zn concentration in the prostate is substantially lower in cancerous tissue compared to benign prostate hyperplasia (BPH) and normal prostate tissue. Zaichick et al, (1997) reported dry weight Zn concentrations of 1018 ± 124, 1142 ± 77 and 146 ± 10 μg/g for normal, BPH and cancerous prostate, respectively. In addition, they found that the decrease in Zn levels in cancer starts at very early stages of the disease and there is a lack of Zn level dependence on the stages of the disease and on histological cancer grading. Zinc levels are modified only in the cancerous tissue. Tissue not involved in the tumor process remain unaltered and zinc levels in visually and morphologically intact tissues are at normal levels. It is important to note that the Zn levels in prostate cancer appraochapprcjach the typical levels normally associated with non-prostate tissue, which would indicate that the malignant prostate epithelial cells have lost the ability to accumulate zinc. Based on this finding, Habib et al, 1979, suggested that the decrease in zinc was an early step in malignancy and could be used for early diagnosis of prostate cancer. It has been suggested that decreased zinc accumulation occurs in cell population prior to their histopathological identification as malignant cells and that this represents biochemical changes early in the malignant process, possibly as a premalignant stage (Cotran et al, 1999). In view of the above findings and due to the fact that in most of the cases, carcinoma of the prostate originates in the peripheral zone of the gland, classically in a posterior location accessible through the rectum, it seems plausible that in vivo measurement of Zn in the prostate is feasible and could aid in more reliable differentiation between cancerous tissue and that of benign prostate hyperplasia and normal tissue. Thus, it may reduce the rate of false-negative diagnosis and therefore the required number of biopsies, with the important consequence of cost reduction in healthcare. Moreover, it may reduce the rate of false-negative diagnosis, thus minimizing the mortality from undetected prostate cancer. The important observation by Zaichick et al, 1997, that zinc concentration is modified only in the affected tissue pmay permit cancer staging by mapping the 5 distribution of Zn within the prostate. This aspect is most important at the preoperative stage. It is the basis for decisions regarding the recommended treatment, whether partial- or radical-surgical or other type of treatment. SUMMARY OF THE INVENTION In accordance with the invention a novel probe, apparatus and method are 1 0 provided that permit effective detection of Zn and other elements in human prostate tissue in vivo. These are useful for the diagnosis and staging of prostate cancer. In accordance with the present invention, the X-ray fluorescence (XRF) technique is used in detection of Zn and other elements in vivo in the human prostate. In XRF, the analyzed tissue is exposed to a low radiation dose of X-rays or 1 5. low energy gamma-ravsgamma rays from an X-ray tube or an isotopic radioactive source. This radiation causes the excitation of the atoms present in the tissue, which in turn decay by emission of characteristic fluorescent X-rays. The characteristic X-rays emitted from the irradiated area are detected and counted by a detector with high energy-resolution. The intensity of these X-rays is directly proportional to the 2 0 concentration of the elements inside the tissue. In case of Zn, the characteristic X-ray energies are 8.6 and 9.6 keV. In the following the term "determine" or "determination" will, at times, be used to denote one or both of qualitative determination, namely detecting the presence of a certain element in the prostate tissue, or quantitative determination, 25 namely determination of the amount or level of an element in the tissue. The present invention, in one of its aspects, relates to a probe for in vivo detection of chemical elements in the prostate, said probe comprising a radiation source, a radiation detector and a radiation-collimation system, said detection being through XRF. In one preferred embodiment, the chemical element to be detected in Zn. In other embodiments, the element may be any other element normally present in the prostate glad tissue such as Fe, Ca, or Br. These elements may be determined simultaneously with Zn by the XRF technique and can serve for normalization purposes. In another embodiment, the elements to be determined are elements that are introduced into the prostate for the purpose of a specific medical procedure, for example, for therapeutic purposes. These can, for example, be palladium (Pd), in the form of Pd-porphyrin compounds used in photodynamic therapy (PDT). The radiation source is a source that generates radiation of an energy and wavelength such that it can excite elements to emit a fluorescent X-ray radiation. The radiation source may be selected from a radioactive source, an X-ray tube, a synchrotron light source, an X-ray beam guide connected to an external X-ray source, a miniature plasma X-ray generator and others. A radioactive source may for example by Cd. An X-ray tube may, for example, be a miniature X-ray tube such as, for example, plasma X-ray source. When used for tissue mapping, said radiation source is typically a scanning source. The radiation detector may be selected from a high energy-resolution solid state detector such as detectors based on Silicon (Si), Silicon-Lithium-drifted (Si(Li)), Mercury Iodide (Hgl 2 ) or Cadmium-Zinc Telluride (CdZnTe), which can be cooled by a small thermoelectric device, or any other detector sensitive to X-rays, or an array of such detectors. When used for mapping, said radiation detector is typically a scanning detector or a position-sensitive detector. In case of a scanning detector, its scan is essentially synchronized with the scan of the radiation source. The collimation system that is generally known per se, should prevent the said radiation detector from directly receiving any radiation emitted from the said radiation source, and to receive only radiation emitted from the elements in the prostate tissue under investigation. The collimieation system should be constructed of materials whose characteristic X-rays do not interfere with the deteπnination of the tissue elements particularly Zn. It is known that in most cases (70-80%), carcinoma of the prostate originates in the peripheral zone of the posterior lobe, which may be diagnosed by access through the rectum. For the purpose of diagnosing other (central) parts of the prostate access is preferably through the urethra. Thus, the probe according to the invention may be adapted for both transrectal orboth transrectal and transuretjhral examination. Alternatively, two probes may be provided, one a rectal probe and the other a urethral probe. In one embodiment, the transrectal probe may be combined with or may include a transrectal ultrasound probe (TRUS). In another embodiment, the transrectal or transurethral probe includes a biopsy device. In still another embodiment, the transrectal or transurethral probe includes a device for injection of a drug, in which case the probe both localizes the cancerous areas of the prostate and injects into the drug that may be a therapeutic drug or a drug for tissue imaging, e.g. a contrast agent. In an additional embodiment, the probe includes a device for illumination of an identified cancerous site with a light beam. The light beam is typically a selected therapeutic wavelength for photodynamic therapy. In another embodiment the probe can be used as a detector for radioactive substances introduced into the prostate for diagnostic purposes, for example, radioactive I or Zn. In such a mode of operation, the exciting radiation emanating from the probe is typically turned off. This may be done through a peripheral device or through an ON/OFF switch included within the probe. In a further embodiment, the probe of the invention may be used as an interoperative probe. In another aspect, the present invention relates to an apparatus for in vivo detection of chemical elements in the prostate by X-ray fluorescence comprising a probe of the invention, a signal amplification unit and a signal recording, processing and displaying system. In still another aspect, the present invention provides a method for in vivo detection of one or more chemical elements in the prostate comprising: (a) introducing a probe of the invention transrectally in close proximity to the posterior lobe of the prostate of said individual or transurethrally in close proximity to the lobus medius of the prostate of said individual; and (b) irradiating the prostate by the radiation source while simultaneously measuring emitted characteristic fluorescent X-ray radiation of the elements present in the prostate. For determination of the level of a meas red element in the prostate, the intensity of the fluorescent X-ray radiation may be measured, such intensity being in correlation with said level. Thus, for determining said level the method further comprises: (c) determining the intensity of the characteristic fluorescent X-ray radiation; and (d) calculating the level of each of said elements in the prostate based on the measured intensity of said radiation. The level of an element may be determined by absolute fluorescent radiation levels, although this may introduce inaccuracy since the absolute measured fluorescent radiation may depend on a number of factors such as probe position, e.g. distance of the probe from the tissue, probe sensitivity and others. Thus for a quantitative determination, a normalizing measurement of a reference element whose level is relatively constant may be made and the equal determination of the level may then be made in comparison to the reference element, for example, a reference element is Fe, Ca or Br. In one preferred embodiment, the invention provides a method for diagnosing prostate cancer in an individual comprising: (a) introducing a probe of the invention transrectally in close proximity to the posterior lobe of the prostate of said individual or transurethrally in close proximity to the lobus medius of the prostate of said individual; (b) irradiating the prostate by the radiation source while simultaneously 5 measuring emitted characteristic fluorescent X-ray radiation of Zn present in the prostate; (c) determining the intensity of the fluorescent X-ray radiation; and (d) calculating the level of Zn in the prostate based on the measured intensity of said radiation, a level of Zn below a threshold level indicating a high l o probability of a cancerous pathological condition of the prostate. The method of the invention may also involve the measurement of the level of radioactive elements introduced to the prostate by either systemic or local administration (into the prostate or proximal thereto). This may be useful in staging of the disease. l o 1 5 In one preferred embodiment, the introduced radioactive element is I and a modification in the 125 I concentration levels in the prostate indicates a cancerous pathological condition of the prostate. According to the present invention, experiments were carried out demonstrating that zinc can be accurately measured in the prostate by the XRF 20 method without interference from other elements. It has been further found in accordance with the present invention that the optimal energy of the incident radiation source for detection of Zn is in the range of 15-20 keV. The measurement is performed by introducing the probe through the rectum in close proximity to the peripheral zone of the prostate, or through the urethra, in 25 proximity to the central region of the prostate gland. Prostate tissue is irradiated by the incident source radiation and the characteristic element X-rays due to said element, e.g. Zn, present in the tissue are emitted from the tissue and are measured by the radiation detector. The intensity of these X-rays is proportional to the concentration of said element, e.g. Zn, in the prostate tissue. By scanning the prostate with the probe it is possible to obtain the distribution of Zn in the region under examination and thus locate regions of varying Zn concentrations, a procedure which can have an importance for staging the prostate cancer and then choosing the best therapeutic approach and procedures. A combination of the proposed method with other mapping methods such as TRUS provides an improved accuracy for a variety of medical purposes such as for biopsy procedures. BRIEF DESCRIPTION OF THE DRAWINGS In the following some specific embodiments of the invention will be described with reference to the annexed drawings in which: Fig. 1 depicts a diagrammatic illustration of a transrectal or transurethral in vivo elemental (e.g. Zn) probe according to the invention. Fig. 2 depicts a schematic view of a system used for in vitro determination of Zn in prostate phantom. Fig. 3 is an XRF spectrum obtained from a prostate phantom vial containing 1000 μg/g of Zn in aqueous solution, with the system of Fig. 2. Fig. 4 is an XRF spectrum (logarithmic vertical scale) obtained from a prostate sample diagnosed for adenoma. Fig. 5 is an XRF spectrum (logarithmic vertical scale) obtained from a prostate sample diagnosed for cancer. Fig. 6 is the illustration of the transrectal prostate examination procedure using the probe of the invention. DETAILED DESCRIPTION OF THE INVENTION The invention relates to a probe, apparatus and method for non-invasive, in vivo determination of elements, particularly Zn, in the human prostate. The method is useful as a diagnostic tool for prostate cancer, particularly early prostate cancer and for cancer staging. In one preferred embodiment, the instrument used for diagnosis consists of an X-ray fluorescence (XRF) system including a rectal probe, which is brought in close proximity to the backside (posterior) region of the prostate, known as the region where most cases of cancer begin their development. The probe contains a small X-ray source, of a moderate intensity, that irradiates the prostate and a detector that records and at times also maps the characteristic X-rays re-emitted from the prostate. By this technique, it is possible to evaluate the Zn concentration in the prostate with good accuracy and to obtain the required information about its distribution. Since Zn concentrations in the prostate are about 5 times lower in cancerous tissue compared to normal and benign prostate hyperplasia (BPH), an accurate in vivo mapping of Zn concentration by the method of the invention will have a significant impact on the diagnosis reliability and on preoperative staging. In addition, it is expected that mapping the Zn content in the tissue will provide a clear outline of the cancerous region whichregion, which may aid prostate cancer therapy. X-ray fluorescence (XRF) is an analytical method widely used for analysis of trace elements in various matrices. Biological samples such as tissues can be analyzed intact by XFR without sample processing. In XFR, the analyzed tissue may be exposed to a low radiation dose of X-rays or low energy gamma rays from an X-ray tube or an isotopic radioactive source. This radiation causes the excitation of the atoms present in the tissue, which in turn decay by emission of characteristic fluorescent X-rays. The characteristic X-rays emitted from the sample are detected and counted by a high energy-resolution detector. The intensity of these X-rays is directly proportional to the concentration of the elements inside the tissue. In the case of Zn, the characteristic fluorescent X-ray energies are 8.6 and 9.6 keV. The sensitivity of the XFR method is dependent on the element in question and on the experimental conditions. The limits of detection are usually below 1 μg g, e.g. 1 part per million. The method according to the invention is best explained with reference to Fig. 1. As shown, a probe 1 is placed in a close proximity to the prostate 2, which may contain a tumor 8. A radiation source 3 emits X-rays 4 of a desired energy and flux so as to impinge on the prostate tissue. This radiation causes the excitation of Zn atoms 7 present in the tissue, which in turn decay by emission of characteristic fluorescence X-rays 5. These characteristic X-rays emitted from the tissue are detected and counted by a high energy-resolution detector 6 electrically linked to a recorder outside the probe. Source 3 may, for example, be a radioactive source, an X-ray tube, a synchrotron light source, an X-ray beam guide connected to an external X-ray source or miniature plasma X-ray generator. The energy of the incident exciting photons is dictated by the energy behavior of the cross-section for the excitation of a given element and by the background produced by scattering of the incident radiation on the large mass of surrounding tissue. In order to reduce this background, the energy of the incident radiation should be well above the characteristic Zn X-rays (8.6 and 9.6 keV). On the other hand, the cross-section for the excitation of Zn decreases for energies above 9.66 keV (the K-edge energy of Zn). The determination of the optimal energy of the incident radiation and a feasibility of the in vivo Zn determination according to the invention was demonstrated in the laboratory using a prostate phantom in the form of a polyethylene vial filled with aqueous Zn solution. The experimental arrangement is shown in Fig. 2. The radiation source was a filtered X-ray beam 20 from a tungsten anode X-ray tube 22. The tube 22 was operated at 36 kV and the filter 24 was a combination of Cu Mo foils. The diameter of the beam on the sample 26 was about 10 mm. A ferrous collimator 28 was included in the beam's path. The irradiated samples consisted of 30 cc polyethylene vials, 34 mm in diameter and 1 mm thick wall, containing aqueous solutions of Zn. The Zn characteristic X-rays were emitted from the sample and detected by Si(Li) detector 30 (5 mm 2 in area) co jjded by a liquid nitrogen (LN 2 ) arrangement 32. Fig. 3 shows a spectrum obtained from irradiation of a vial containing 1000 μg/g of Zn aqueous solution. As can be observed the Zn peak is very well defined and is positioned on a flat background. The small peak on the left side is due to Cu most probably present in the detector structure or housing. From this preliminary study it can be concudedconcluded that the optimal source X-ray energy for detection of Zn is in the range of 15-20 keV. The complexity of the detected X-ray spectrum was tested iftg in vitro using the XRF method on prostate samples and indicated that Zn in prostate can be accurately measured without interference from other elements. The samples were exposed to X-rays emitted from an X-ray tube with a Mo anode. The tube operated at 27 keV and the characteristic Mo X-ray line of 17.44 keV was filtered out using a crystal monochromator. The characteristic radiation emitted from the sample was measured using a Si(Li) detector having energy resolution of 160 eV at 6.4 keV. Fig. 4 and Fig. 5 show the XRF spectra obtained from prostate specimens embedded in paraffin, prepared for histological examination. As can be observed from the spectra, the Zn concentration in the cancerous tissue is much smaller than in the prostate with adenoma. Other elements such as Ca and Fe are also measurable and can be used for normalization purposes. For example, the ratio of Zn/Fe in the tissue was about 7 times lower in the case of prostate cancer. The X-ray detector 6 can be a high energy-resolution detector such as for example cooled Si, Si(Li), Hgl 2 , CdZnTe or other detectors sensitive to X-rays of 8-10 keV or an array of such detectors. The detector is designed to measure the charactersiticcharacteristic Zn X-ray lines (8.6 and 9.6 keV) emitted from the examined tissue under the X-ray irradiation. Care must be taken to avoid Cu or brass in the construction of the probe, because of the presence of Zn in brass and the proximity of the Cu characteristic lines (8.04 and 8.904 keV) to that of Zn. Fig. 6 depicts schematically the measurement procedure. The measurement will be performed by introducing the probe through the rectum in close proximity to the peripheral zone of the prostate. By irradiating a small area of the prostate it is possible to determine the distribution of Zn in the peripheral zone, simply by moving the probe to different positions. This is of importance for staging of the prostate cancer. Use of an array of detectors or a position-sensitive detector, will eliminate the need for scanning and will provide zinc concentration mapping in a single measurement. The elemental (e.g. Zn) mapping is important also for cancer therapy, since it can guide the treatment into the cancerous regions. Thus the recently proposed PDT can benefit from the information about the tumor localization and dimensions. A combination of the proposed transrectal or transurethral probe with other mapping methods such as TRUS could provide an improved accuracy to biopsy procedure. Current ultrasound guided biopsy is unsatisfactory. Due to a low reliability of TRUS image, repeated biopsies are needed, with the risk of infections and extra costs. It is estimated that a radiation dose of about 5 mSv to the peripheral tissue of the prostate will be required in order to detect Zn concentration with a statistical precision of about 5%.

Claims: CLAIMS: I. A probe for in vivo detection of chemical elements in the prostate, said probe comprising a radiation source, a radiation detector and a radiation-collimation system, the detection being by X-ray fluorescence. 2. The probe according to Claim 1, wherein the chemical element to be detected is Zn, Fe, Ca, Br, or Pd. 3. The probe according to Claim 2, wherein the chemical elements to be detected is Zn. 4. The probe according to any one of Claims 1 to 3, wherein said radiation source is selected from a radioactive source, an X-ray tube, a synchrotron light source, an X-ray beam guide connected to an external X-ray source or a miniature plasma X-ray generator. 5. The probe according to Claim 4, wherein said radiation source is a scanning source. 6. The probe according to any one of Claims 1 to 5, wherein said radiation detector is selected from a high energy-resolution solid state detector, or an array of such detectors. 7. The probe according to Claim 6, wherein said radiation detector is a scanning detector or a position-sensitive detector. 8. The probe according to any one of Claims 1 to 7, wherein said probe is adapted for transrectal examination. 9. The probe according to any one of Claims 1 to 7, wherein said probe is adapted for transurethral examination. 10. The probe according to Claim 8, wherein said probe is combined with or includes a transrectal ultrasound probe. II. The probe according to any one of Claims 1 to 9, wherein said probe includes a biopsy device. 12. The probe according to any one of Claims 1 to 9, wherein said probe includes a device for injection of a drug. 13. The probe according to any one of Claims 1 to 9, wherein said probe includes a device for illumination of the tumor with light. 14. The probe according to any one of Claims 1 to 9, for use as an interoperative probe. 15. The probe according to any one of Claims 1 to 9, includes a switch for turning ON or OFF the radiation source. 16. The probe according to Claim 15, wherein said probe is used as a radiation detector only, for detection of radioactive elements introduced for diagnostic purposes. 17. An apparatus for in vivo detection of chemical elements in the prostate by X-ray fluorescence comprising a probe according to any one of Claims 1 to 16, a power supply, a signal amplification unit and a signal recording, processing and displaying system. 18. A method for in vivo detection of one or more chemical elements in the prostate comprising: (a) introducing the probe that can detect chemical elements in a tissue and that comprises a radiation source, a radiation detector and a radiation-collimation system, the detection being by X-ray fluorescence transrectally in close proximity to the posterior lobe of the prostate of said individual or transurethrally in close proximity to the lobus medius of the prostate of said individual; and (b) irradiating the prostate by the radiation source while simultaneously measuring emitted characteristic fluorescent X-ray radiation of the elements present in the prostate. 19. A method according to Claim 18, further comprising: (c) determining the intensity of the characteristic fluorescent X-ray radiation; and (d) calculating the level of each of said elements in the prostate based on the measured intensity of said radiation. 20. A method for diagnosing prostate cancer in an individual comprising: (a) introducing the probe that can detect Zn in a tissue and that comprises a radiation source, a radiation detector and a radiation-collimation system, the detection being by X-ray fluorescence transrectally in close proximity to the posterior lobe of 5 the prostate of said individual or transurethrally in close proximity to the lobus medius of the prostate of said individual; (b) irradiating the prostate by the radiation source while simultaneously measuring emitted characteristic fluorescent X-ray radiation of Zn present in the prostate; 10 (c) determining the intensity of the fluorescent X-ray radiation; and (d) calculating the level of Zn in the prostate based on the measured intensity of said radiation, a level of Zn below a threshold level indicating a high probability of a cancerous pathological condition of the prostate. 1 5 21. A method according to Claim 20, comprising scanning the prostate and determining the level of Zn at different regions of the prostate, and based thereon, determining the stage of the prostate cancer. 22. A method according to any one of Claims 18 or 19, comprising determining the level of an introduced radioactive element in the prostate. 20 23. A method according to Claim 22, wherein the increase of intensity of radiation of said radioactive element indicates the presence of a tumor in the prostate. 24. A method according to Claim 23, wherein said radioactive element is radioactive 125 I. 25 25. A method according to Claim 18 or 19, wherein the level of an assayed element is compared to a level of reference elements.

Inventors: BRESKIN AMOS, CHECHIK RACHEL, VARTSKY DAVID, BRESKIN, AMOS, CHECHIK, RACHEL, VARTSKY, DAVID
Applicants: BRESKIN AMOS, CHECHIK RACHEL, SOREQ NUCLEAR RES CT ISRAEL AT, VARTSKY DAVID, YEDA RES & DEV, BRESKIN, AMOS, CHECHIK, RACHEL, SOREQ NUCLEAR RESEARCH CENTER ISRAEL ATOMIC ENERGY COMMISSION, VARTSKY, DAVID, YEDA RESEARCH AND DEVELOPMENT COMPANY LTD.
Application year: 2001
Main classification: A61B6
IPC codes: A61B6