Search results for "Dosimetry"

Time-resolved pulsed OSL of ceramic YAP:Mn phosphors

2019

The paper deals with the results of comparative study on time-resolved pulsed optically stimulated luminescence (TR-OSL) response of ceramic YAP:Mn materials prepared by different methods. In parti...

Dosimetric Impact of Interfractional Variations in Prostate Cancer Radiotherapy—Implications for Imaging Frequency and Treatment Adaptation

2019

Background and purpose: To analyze deviations of the applied from the planned doses on a voxel-by-voxel basis for definitive prostate cancer radiotherapy depending on anatomic variations and imaging frequency. Materials and methods: Daily in-room CT imaging was performed in treatment position for 10 patients with prostate cancer undergoing intensity-modulated radiotherapy (340 fraction CTs). Applied fraction doses were recalculated on daily images, and voxel-wise dose accumulation was performed using a deformable registration algorithm. For weekly imaging, weekly position correction vectors were derived and used to rigidly register daily scans of that week to the planning CT scan prior to d…

Evaluation of Safety and Dosimetry of 177Lu-DOTA-ZOL for Therapy of Bone Metastases

2021

Palliative treatment of bone metastasis using radiolabeled bisphosphonates is a well-known concept proven to be safe and effective. A new therapeutic radiopharmaceutical for bone metastasis is 177Lu-DOTA-zoledronic acid (177Lu-DOTA-ZOL). In this study, the safety and dosimetry of a single therapeutic dose of 177Lu-DOTA-ZOL were evaluated on the basis of a series of SPECT/CT images and blood samples. Methods: Nine patients with exclusive bone metastases from metastatic castration-resistant prostate cancer (mCRPC) (70.8 ± 8.4 y) and progression under conventional therapies participated in this prospective study. After receiving 5,780 ± 329 MBq 177Lu-DOTA-ZOL, patients underwent 3-dimensional …

Radiation dose distribution in functional heart regions from tangential breast cancer radiotherapy

2015

Abstract Background and purpose To analyze the distribution of individually-determined radiation dose to the heart and its functional sub-structures after radiotherapy in breast cancer patients treated in Germany during 1998–2008. Material and methods We obtained electronic treatment planning records for 769 female breast cancer patients treated with megavoltage tangential field radiotherapy. All dose distributions were re-calculated using Eclipse with the anisotropic analytical algorithm (AAA) for photon fields, and the electron Monte Carlo algorithm for electron boost fields. Based on individual dose volume histograms for the complete heart and several functional sub-structures, we estima…

Biodosimetry Based on γ-H2AX Quantification and Cytogenetics after Partial- and Total-Body Irradiation during Fractionated Radiotherapy

2015

The aim of this current study was to quantitatively describe radiation-induced DNA damage and its distribution in leukocytes of cancer patients after fractionated partial- or total-body radiotherapy. Specifically, the impact of exposed anatomic region and administered dose was investigated in breast and prostate cancer patients receiving partial-body radiotherapy. DNA double-strand breaks (DSBs) were quantified by γ-H2AX immunostaining. The frequency of unstable chromosomal aberrations in stimulated lymphocytes was also determined and compared with the frequency of DNA DSBs in the same samples. The frequency of radiation-induced DNA damage was converted into dose, using ex vivo generated ca…

Retrospective dosimetry for Latvian workers at Chernobyl.

2001

Between 1986 and 1991 approximately 6500 Latvian inhabitants were recruited for clean-up work at the Chernobyl nuclear power plant. Their absorbed doses are usually unknown, because less than half of them had their external exposure officially documented. Clinical investigations show a high morbidity rate for these clean-up workers when compared with that of the general population. In order to understand the causes of their diseases and the impact of ionising radiation, electron spin resonance (ESR) has been used to measure the absorbed doses in human tooth enamel. The doses estimated by ESR were between two and three times higher than previously documented and are in accord with the result…

Could alanine/EPR dosimetry be useful for ultra-high dose rate beams used for FLASH radiotherapy?

In the last years a large interest has aroused towards radiation therapy treatments with dose rates much larger with respect to the conventional ones since experiments support the evidence of a considerable normal tissue sparing effect. Indeed, in-vivo experiments showed an increasing of the therapeutic window for dose rates over 50 Gy/s [2]. If confirmed, the ‘FLASH effect’ has the potential to re-shape the future of radiation treatments, with a significant impact on many oncology patients. Significant dosimetric challenges should be dealt with for Ultra-high dose rate (UHDR) beams for FLASH radiotherapy [4]. In particular, ionization chambers are affected by ion recombination effects, alt…

Dosimetric characterization of an ultra-high dose rate beam for FLASH radiotherapy through alanine EPR dosimetry

2022

Experimental evidence is growing, supporting the evidence of a considerable normal tissue sparing effect when treatments are delivered with dose rates much larger with respect to the conventional ones [1]. In particular, an increasing of the therapeutic window has been demonstrated for dose rates over 50 Gy/s, over a large variety of in-vivo experiments [2]. If confirmed, the ‘FLASH effect’ has the potential to re-shape the future of radiation treatments, with a significant impact on many oncology patients [3]. Ultra-high dose rate (UHDR) beams for FLASH radiotherapy present significant dosimetric challenges [4]. Ionization chambers are affected by ion recombination effects, although novel …

ALANINE/ESR DOSIMETRY FOR TOTAL BODY IRRADIATION USING AN ANTHROPOMORPHIC PHANTOM

2016

Introduction: Total Body Irradiation (TBI) is a technique widely used in the radiation blood-oncology in the treatment of patients that need bone marrow transplantation or peripheral stem cell transplantation. This technique has some limitations such as the lack of homogeneity of the dose distribution (which may show variations of 20% in the different areas), irradiation of critical organs such as the lungs, the liver, the intestine and the eye-lens which can receive a dose comparable to that nominal and require appropriate shielding and a proper evaluation of the dose absorbed by them. The positive outcome of this type of radiation therapy is strictly related to a precise and accurate meas…

Dosimetry to Electron Spin Resonance (ESR) using organic compounds (alanine and ammonium tartrate) for mixed neutron-gamma fields

2015

Alongside with the development of Neutron Capture Therapy (NCT) and the use of thermal neutrons for radiotherapeutic purposes, many efforts have been devoted to the characterization of the beam in order to optimize therapy procedures. Reliable dose measurements should be able to determine the various (neutrons and photonic) components of the mixed beam usually employed for therapy. This paper studies the effect of additives such as Boric and Gadolinium nuclei on the sensitivity of neutron organic (alanine and ammonium tartrate) dosimeters analyzed through Electron Spin Resonance (ESR) technique. These dosimeters were exposed to a mixed (neutron-gamma) field mainly composed of thermal neutro…