A colon imaging system, comprising : a) a contrast agent solution comprising : a contrast agent; and nanoparticles , which are designed to adhere to cancerous tissue ; b) an imaging capsule , comprising: a. a radiation source providing X-Ray and gamma radiation with energies sufficient to induce X-Ray fluorescence from the nanoparticles that adhere to cancerous tissue , and which were administered to a patient in the contrast agent solution prior to examining the colon with the imaging capsule ; b. a detector for detecting particle energy of particles emitted responsive to the provided radiation and forming count information disclosing a number of particles detected for each energy level; wherein the detector is configured to detect energy levels representing X-Ray fluorescence resulting from radiating the nanoparticles and also the energy levels of X-ray fluorescence and Compton backscattering from the contrast agent; c. a transceiver for transferring the count information to an external computer for analysis; c) a computer for constructing images of an inside of the colon based on the count information; wherein the images provide an indication of locations in the colon of which the nanoparticles adhere to. a) a contrast agent solution comprising : a contrast agent; and nanoparticles , which are designed to adhere to cancerous tissue ; a contrast agent; and nanoparticles , which are designed to adhere to cancerous tissue ; b) an imaging capsule , comprising: a. a radiation source providing X-Ray and gamma radiation with energies sufficient to induce X-Ray fluorescence from the nanoparticles that adhere to cancerous tissue , and which were administered to a patient in the contrast agent solution prior to examining the colon with the imaging capsule ; b. a detector for detecting particle energy of particles emitted responsive to the provided radiation and forming count information disclosing a number of particles detected for each energy level; wherein the detector is configured to detect energy levels representing X-Ray fluorescence resulting from radiating the nanoparticles and also the energy levels of X-ray fluorescence and Compton backscattering from the contrast agent; c. a transceiver for transferring the count information to an external computer for analysis; a. a radiation source providing X-Ray and gamma radiation with energies sufficient to induce X-Ray fluorescence from the nanoparticles that adhere to cancerous tissue , and which were administered to a patient in the contrast agent solution prior to examining the colon with the imaging capsule ; b. a detector for detecting particle energy of particles emitted responsive to the provided radiation and forming count information disclosing a number of particles detected for each energy level; wherein the detector is configured to detect energy levels representing X-Ray fluorescence resulting from radiating the nanoparticles and also the energy levels of X-ray fluorescence and Compton backscattering from the contrast agent; c. a transceiver for transferring the count information to an external computer for analysis; c) a computer for constructing images of an inside of the colon based on the count information; wherein the images provide an indication of locations in the colon of which the nanoparticles adhere to. <EOS>