Rhenium-188 (Re-188) is a high energy β-emitting radioisotope obtained from the tungsten-188/rhenium-188 (W-188/Re-188) generator, which has shown utility for a variety of therapeutic applications in nuclear medicine, oncology, and interventional radiology/cardiology. Re-188 decay is accompanied by a 155 keV predominant energy γ-emission, which could be detected by γ-cameras, for imaging, biodistribution, or absorbed radiation dose studies. Its attractive physical properties and its potential low cost associated with a long-lived parent make it an interesting option for clinical use. The setup and daily use of W-188/Re-188 generator in hospital nuclear medicine departments are discussed in detail. The clinical efficacy, for several therapeutic applications, of a variety of Re-188-labeled agents is demonstrated. The high energy of the β-emission of Re-188 is particularly well suited for effective penetration in solid tumours. Its total radiation dose delivered to tissues is comparable to other radionuclides used in therapy. Furthermore, radiation safety and shielding requirements are an important subject of matter. In the case of bone metastases treatment, therapeutic ratios are presented in order to describe the efficacy of Re-188 usage.

Rhenium-186 (Re-186) is a β-emitting radionuclide. Emitted β-particles have ranges up to 4.5 mm in tissue, capable of delivering high doses to skeletal regions of high Re-186 concentrations while sparing adjacent radiosensitive regions and thus making the irradiation well tolerated for the patient. Along with the β-emissions, γ-rays are emitted having an adequate energy for imaging during therapy and biodistribution assessment for patient-specific dosimetry calculations. The relatively short physical half-life combined with the β-emissions allows the delivery of relatively high activity rate for a short period of time in areas of concentration. This study is a short review concerning the palliative treatment of skeletal metastases using 186Re-HEDP. After presenting the dominant ways of 186Re production, special emphasis is given to dosimetry issues while the effect of palliation therapy can be evaluated through the comparison of the absorbed dose in metastatic lesion relatively to the normal bone region. Accurate dose estimation is required taking into account the anatomic individual difference of each patient. For this purpose a patient specific dosimetric model considering metastatic lesions as spherical nodules is introduced. In order to quantify in a representative way the results of palliation treatment, the concept of therapeutic ratios is analyzed.

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Introduction: Low-dose Whole Body Multi-Detector Computed Tomography (MDCT) has been established as an alternative to conventional X-ray imaging for Multiple Myeloma (MM) diagnosis. During an MDCT scan two dose indices are displayed on the monitor to account for the dose delivered to the patient: the volume computed tomography dose index (CTDI vol ) and the dose length product (DLP). Both parameters though, are not sufficient in estimating the actual dose on their own. Two methods are proposed to promptly evaluate the scan dose, based on the two indices displayed: an effective dose evaluation through the DLP (Huda et al, 2008) and the Size-Specific Dose Estimate (SSDE), which also takes into account the patient's size, based on the CTDI vol (AAPM Report 204). Material and method:In this study a standardized protocol was developed and data from a good number of clinical examinations were collected. Effective dose was calculated based on the scanner displayed DLP. SSDE calculations were based on the scanner displayed values for the CTDI vol . SSDE is the averaged patient dose within the scan volume corrected for patient size. Dose is estimated using both methods for a set of 85 patients, examined for MM, for the torso body part. Although these indices are quite different in principle, they both present a rough but fast and prompt evaluation of the delivered dose. The results of the two methods are presented and evaluated.Result: Calculated ED and SSDE values were found to present a weak correlation. Pairwise comparisons showed that the dose values through the two methods differed significantly (P < 0.001) by (0.92 ± 0.79) mSv. The Bland-Altman plot showed that the 95% LOA is 3.1 mSv wide, yelding a relatively poor agreement between the two methods. Conclusion:The two methods of evaluation of the CT scan dose indices, ED and SSDE, based on DLP and CTDI vol correspondingly, provide an easily applicable dose estimation of a CT scan, but their values are found to present a notable difference. This means that they can not be used interchangeably clinically, but the most appropriate one should be used accordingly. ED relies on standardized phantoms and therefore has shortcomings with respect to its ability to reflect any individual patient effective dose. The SSDE is a good tool for estimating the average radiation dose for a given patient depending on the input parameters and the dimensions of the specific person in question but does not incorporate any organ/tissue weighting factors. It is recommended that when examined patients deviate significantly from the reference person by ICRP, dose should be estimated through the SSDE method. It is also proposed that tissue weighting factors would be incorporated with the SSDE methodology to provide a more refined estimate of risk.