【論文摘要】Imaging and Dosimetry of Ra-223 in the Treatment for Bone Metastasis in Patients With Castration-Resistant Prostate Cancer

Shinro Matsuo ； Masahisa Onoguchi ； Atsushi. Mizokami ； Kazufumi Nakajima ； Hiroshi Mori ； Hiroshi Wakabayashi ； Takayuki Shibutani ； Hiroto Yoneyama ； Seigo Kinuya ； Takeshi Kudo

《核子醫學暨分子影像雜誌》 32卷1期 (2019/03) Pp. 55-56

https://doi.org/10.6332/ANMMI.201903.OC8

摘要

Introduction: Ra-223 selectively targets bone metastases with α particle. Ra-223 also releases gamma rays accompanying α or β rays. However, the therapeutic effect and its radiation dose assessment have not yet been adequately studied. Methods: We investigated the side effects and therapeutic effects of Ra-223 radiation therapy using radiation dosimetry for patients with castration-resistant prostate cancer (CRPC). The study subjects were 28 male patients of with CRPC who underwent radiotherapy radiation therapy at our hospital since June 2016. Bone scintigraphy was performed before and after the therapy in all subjects, as well as the measurement of prostate specific antigen (PSA). Bone scan index and other indices were calculated by boneNAVI software. For evaluation of whole body distribution of Ra-223, planar images and single photon emission computed tomography/computed tomography (SPECT/CT) imaging were carried out in three cases using SPECT/CT apparatus (middle energy general purpose collimators). Results: Our preliminary findings obtained in our institution was that bone scan index was useful in monitoring the patients regarding pre- and post-treatment and it can be a future prognostic indicator for Ra-223 treatment when alpha treatment can be monitored with bone scan index of boneNAVI. Detailed information on bone metastasis site and non-bone metastasis accumulation site and irradiation dose evaluation was possibly obtained with radiation dosimetry. The accumulation of normal tissue was found to be low in relation to targeted tumor cell. We also observed symptom regarded as side effects in half of the subjects. The side effects included as well as side effect of bone pain loss, exacerbation, loss of appetite, etc. during treatment. There was a significant relationship between the site of Ra-223 accumulation and the symptom of side effects by the treatment. The evaluation of radiation exposure dose in the non-target organ including intestine, bone, and urinary cyst could be recognized with Ra-223 imaging. Conclusions: α treatment can be monitored by nuclear medicine survey detectors under optimization of measurements. Imaging and dosimetry of Ra-223 demonstrates the feasibility in the managements of CRPC.