ESR dosimetry of 89Sr and 153Sm in bone

Electron spin resonance (ESR) dose measurement in bone of Hiroshima A-bomb victim

Explosion of the bombs in Hiroshima and Nagasaki corresponds to the only historical moment when atomic bombs were used against civilians. This event triggered countless investigations into the effects and dosimetry of ionizing radiation. However, none of the investigations has used the victims’ bones as dosimeter. Here, we assess samples of bones obtained from fatal victims of the explosion by Electron Spin Resonance (ESR). In 1973, one of the authors of the present study (SM) traveled to Japan and conducted a preliminary experiment on the victims’ bone samples. The idea was to use the paramagnetism induced in bone after irradiation to measure the radiation dose. Technological advances involved in the construction of spectrometers, better knowledge of the paramagnetic center, and improvement in signal processing techniques have allowed us to resume the investigation. We obtained a reconstructed dose of 9.46 ± 3.4 Gy from the jawbone, which was compatible with the dose distribution in different locations as measured in non-biological materials such as wall bricks and roof tiles.

Application of EPR dosimetry in bone for ex vivo measurements of doses in radiotherapy patients

In the present study, bone samples from three patients treated in radiotherapy facilities in Poland were used for the determination of doses absorbed during radiotherapy. The samples were obtained during surgical treatments of patients performed due to medical indications. For the purpose of retrospective dosimetry, sensitivity of the radiation-induced EPR signal was individually calibrated in the samples by re-irradiation of the samples with known doses. The doses reconstructed in bones extracted within 6 months after irradiation were consistent with those calculated by treatment planning systems. The dose reconstructed in the bone removed 6 y after radiotherapy was ∼14% lower than the calculated one.

Effects of water treatment and sample granularity on radiation sensitivity and stability of EPR signals in X-ray irradiated bone samples

The article describes effects of sample conditions during its irradiation and electron paramagnetic resonance (EPR) measurements on the background (BG) and dosimetric EPR signals in bone. Intensity of the BG signal increased up to two to three times after crushing of bone to sub-millimetre grains. Immersion of samples in water caused about 50 % drop in intensity of the BG component followed by its regrowth in 1-2 months. Irradiation of bone samples produced an axial dosimetric EPR signal (radiation-induced signal) attributed to hydroxyapatite component of bone. This signal was stable and was not affected by water. In samples irradiated in dry conditions, EPR signal similar to the native BG was also generated by radiation. In samples irradiated in wet conditions, this BG-like component was initially much smaller than in bone irradiated as dry, but increased in time, reaching similar levels as in dry-irradiated samples. It is concluded that accuracy of EPR dosimetry in bones can be improved, if calibration of the samples is done by their irradiations in wet conditions.

In vivo dosimetry in the urethra using alanine/ESR during (192)Ir HDR brachytherapy of prostate cancer--a phantom study

A phantom study for dosimetry in the urethra using alanine/ESR during (192)Ir HDR brachytherapy of prostate cancer is presented. The measurement method of the secondary standard of the Physikalisch-Technische Bundesanstalt had to be slightly modified in order to be able to measure inside a Foley catheter. The absorbed dose to water response of the alanine dosimetry system to (192)Ir was determined with a reproducibility of 1.8% relative to (60)Co. The resulting uncertainty for measurements inside the urethra was estimated to be 3.6%, excluding the uncertainty of the dose rate constant Lambda. The applied dose calculated by a treatment planning system is compared to the measured dose for a small series of (192)Ir HDR irradiations in a gel phantom. The differences between the measured and applied dose are well within the limits of uncertainty. Therefore, the method is considered to be suitable for measurements in vivo.

89Sr versus 153Sm-EDTMP: Comparison of treatment efficacy of painful bone metastases in prostate and breast carcinoma

BACKGROUND AND AIM

Painful bone metastases are most frequent in patients with advanced prostate or breast carcinoma. The aim of this study was to compare the analgesic effect of radionuclide therapy using Sr and Sm-EDTMP in patients with painful bone metastases of these tumours.

MATERIAL AND METHODS

One hundred patients treated with radionuclide bone palliation therapy were analysed. The study population consisted of 60 male patients with advanced prostate carcinoma and 40 female patients with advanced breast carcinoma. Fifty patients (30 men and 20 women) were treated with Sr (150 MBq). The other 50 patients were treated with Sm-EDTMP (37 MBq x kg). The treatment efficacy was evaluated by a visual analogue scale (VAS), Karnofsky performance scale, and dosage of analgesic drugs used.

RESULTS

Complete pain relief was found in 40% of women and 40% of men treated using Sm-EDTMP and in 25% of women and 33% of men treated with Sr. No analgesic effect occurred in 20% of patients. A better analgesic effect was found in cases of osteoblastic metastases compared to mixed metastases. Statistically significant reduction of pain intensity, use of analgesic drugs and improvement of performance in Karnofsky scale was found in cases of both radionuclides.

CONCLUSIONS

The analgesic effects of Sr and Sm-EDTMP was similar in both prostate and breast carcinoma. However, the effect was dependent on the type of metastases; better response was observed in cases of osteoblastic metastases than in patients with mixed metastases. Severe adverse reactions after this therapy were rare.

ESR dating of an ancient goat tooth from Nuoro, Sardinia, Italy

The dating of fossil teeth of an ancient goat (Nesogoral melonii) using the electron spin resonance (ESR) technique is reported. This animal was found in the fossiliferous site at Orosei (Nuoro, Sardinia, Italy) and was endemic in the region. Molar teeth were cleaned and enamel was completely removed from dentine. Enamel was irradiated with a 60Co gamma source and measured with an ESR spectrometer (X-band) to obtain the signal vs. dose curve and fitted with an exponential function. The archeological dose obtained by the fitting was 211 +/- 34 Gy. Uranium and thorium concentrations were determined by neutron activation analysis. With the software ROSY the age estimates were 195 +/- 30 ky for early uptake, 247 +/- 40 ky for linear uptake and 243 +/- 40 ky for a combination of uptake processes.

Non-invasive determination of the irradiation dose in fingers using low-frequency EPR

Several reports in the literature have described the effects of radiation in workers who exposed their fingers to intense radioactive sources. The radiation injuries occurring after local exposure to a high dose (20 to 100 Gy) could lead to the need for amputation. Follow-up of victims needs to be more rational with a precise knowledge of the irradiated area that risks tissue degradation and necrosis. It has been described previously that X-band electron paramagnetic resonance (EPR) spectroscopy could be used to assess the dose in irradiated amputated fingers. Here, we propose the use of low-frequency EPR spectroscopy to evaluate non-invasively the absorbed dose. Low-frequency microwaves are indeed less absorbed by water and penetrate more deeply into living material (approximately 10 mm in tissues using 1 GHz spectrometers). This work presents preliminary results obtained with baboon and human fingers compared with human dry phalanxes placed inside a surface-coil resonator. The EPR signal increased linearly with the dose. The ratio of the slopes of the dry bone to whole finger linear regression lines was around 5. The detection limit achievable with the present spectrometer and resonator is around 60 Gy, which is well within the range of accidentally exposed fingers. It is likely that the detection limit could be improved in the future, thanks to further technical spectrometer and resonator developments as well as to appropriate spectrum deconvolution into native and dosimetric signals.

Evaluation of a high dose to a finger from a 60Co accident

Electron spin resonance and fluorescence in situ hybridization were used to evaluate the dose to the finger of a worker who accidentally touched a radiotherapy 60Co therapy source in November 1995. In September 1999, the middle finger was amputated. We estimated the dose to the bone of the finger to be 6.4 +/- 0.5 Gy using the electron spin resonance additive dose method and a corrected dose of about 20 +/- 3 Gy could be inferred by translocation analysis in peripheral lymphocytes using the fluorescence in situ hybridization method. This retrospective dosimetry was performed for the victim 4 y after the accident, but the compatibility of the results obtained by physical and biological methods reinforce their validity, although in the case of partial-body exposure the biological method has limitations and demonstrates the need to find appropriate correction factors.