Radiation dosimetry and biodistribution of 68Ga-FAPI-04 PET in patients with hepatobiliary tumor / 中华放射医学与防护杂志

Objective:To investigate the radiation dosimetry and biodistribution of 68Ga-FAPI-04 PET/CT in patients with hepatobiliary tumor. Methods:A total of six patients with hepatic lesions who underwent PET/CT examination in Peking Union Medical College Hospital were enrolled. After intravenous injection of radiotracer 68Ga-FAPI-04 at (170.57 ± 14.43) MBq, whole-body imaging were performed at the time points of 3, 10, 15, 20, 30 and 60 min, respectively. Biodistribution pattern was observed. Regions of interest were manually delineated. Radiation dosimetry of all target organs were calculated by Olinda/EXM software. Results:The radioactive uptake dissipated gradually in liver whereas it was relatively stable in tumor lesions. The average SUV max of tumor lesions reached the maximum value (13.87± 2.55) at 20 min after injection. The target-to-background ratio increased with time, reaching the maximum value (10.09 ± 8.17) at 30 min after injection. The average effective dose in total body was (0.020 ± 0.002) mSv/MBq and organ with the highest effective dose was bladder wall at (0.146 ± 0.035) mSv/MBq. Conclusions:The effective dose in total body of 68Ga-FAPI-04 was similar to that of 18F-FDG. 68Ga-FAPI-04 is expected to be a PET/CT radiotracer for hepatobiliary tumors in consideration of rapid tumor uptake, low accumulation of liver background, and no influence of blood sugar levels.

Efficacy and dosimetry analysis of image-guided radioactive ¹²⁵I seed implantation as salvage treatment for pelvic recurrent cervical cancer after external beam radiotherapy / 부인종양

OBJECTIVE: To investigate the efficacy of image-guided radioactive 125I seed (IGRIS) implantation for pelvic recurrent cervical cancer (PRCC) after external beam radiotherapy (EBRT), and analyze the influence of clinical and dosimetric factors on efficacy. METHODS: From July 2005 to October 2015, 36 patients with PRCC received IGRIS. We evaluated local progression-free survival (LPFS) and overall survival (OS). RESULTS: The median follow up was 11.5 months. The 1- and 2-year LPFS rate was 34.9% and 20%, respectively. The multivariate analysis indicated recurrence site (central or pelvic wall) (hazard ratio [HR]=0.294; 95% confidence interval [CI]=0.121–0.718), lesion volume (HR=2.898; 95% CI=1.139–7.372), D 90 (HR=0.332; 95% CI=0.130–0.850) were the independent factors affecting LPFS. The 1- and 2-year OS rate was 52.0% and 19.6%, respectively. The multivariate analysis suggested pathological type (HR=9.713; 95% CI=2.136–44.176) and recurrence site (HR=0.358; 95% CI=0.136–0.940) were the independent factors affecting OS. The dosimetric parameters of 33 patients mainly included D 90 (128.5±47.4 Gy), D 100 (50.4±23.7 Gy) and V 100 (86.7%±12.9%). When D 90 ≥105 Gy or D 100 ≥55 Gy or V 100 ≥91%, LPFS was extended significantly, but no significant difference for OS. The 79.2% of 24 patients with local pain were suffering from pain downgraded after radioactive 125I seed implantation. CONCLUSION: IGRIS implantation could be a safe and effective salvage treatment for PRCC after EBRT, which could markedly release the pain. Recurrence site, tumor volume and dose were the main factors affected efficacy. Compared with central recurrence, it was more suitable for patients with pelvic wall recurrent cervical cancer after EBRT.

Dosimetric comparison of IMRT versus 3DCRT for post-mastectomy chest wall irradiation

PURPOSE: To compare the dose distribution of three-dimensional conformal radiation therapy (3DCRT) with intensity-modulated radiation therapy (IMRT) for post-mastectomy radiotherapy (PMRT) to left chest wall. MATERIALS AND METHODS: One hundred and seven patients were randomised for PMRT in 3DCRT group (n = 64) and IMRT group (n = 43). All patients received 50 Gy in 25 fractions. Planning target volume (PTV) parameters—Dnear-max (D2), Dnear-min (D98), Dmean, V95, and V107—homogeneity index (HI), and conformity index (CI) were compared. The mean doses of lung and heart, percentage volume of ipsilateral lung receiving 5 Gy (V5), 20 Gy (V20), and 55 Gy (V55) and that of heart receiving 5 Gy (V5), 25 Gy (V25), and 45 Gy (V45) were extracted from dose-volume histograms and compared. RESULTS: PTV parameters were comparable between the two groups. CI was significantly improved with IMRT (1.127 vs. 1.254, p < 0.001) but HI was similar (0.094 vs. 0.096, p = 0.83) compared to 3DCRT. IMRT in comparison to 3DCRT significantly reduced the high-dose volumes of lung (V20, 22.09% vs. 30.16%; V55, 5.16% vs. 10.27%; p < 0.001) and heart (V25, 4.59% vs. 9.19%; V45, 1.85% vs. 7.09%; p < 0.001); mean dose of lung and heart (11.39 vs. 14.22 Gy and 4.57 vs. 8.96 Gy, respectively; p < 0.001) but not the low-dose volume (V5 lung, 61.48% vs. 51.05%; V5 heart, 31.02% vs. 23.27%; p < 0.001). CONCLUSIONS: For left sided breast cancer, IMRT significantly improves the conformity of plan and reduce the mean dose and high-dose volumes of ipsilateral lung and heart compared to 3DCRT, but 3DCRT is superior in terms of low-dose volume.

Radiation dosimetry estimates of18F-fluoroestradiol based on whole-body PET imaging of mice / 中国癌症杂志

Background and purpose:In preparation for using this tracer in humans, this study estimated thedosimetry of18F-FES with the method established by MIRD based on whole-body PET imaging of mice.Methods:Three female mice receivedⅣ tail injections of18F-FES and were scanned for 160 min in an Inveon dedicated PET/CT scanner. This study selected some important organs (brain, lung, liver, heart wall, small intestine, large intestine, kidney and urinary bladder), computed their residence times. Then, the residence times in mice organs were converted to human values using scale factors based on differences between organ and body weights. OLINDA/EXM 1.1 software was used to compute the absorbed human doses in multiple organs for both adult female and adult male body phantoms. Results:The highest absorbed doses in gallbladder wall, urinary bladder wall, small intestine, upper large intestine and liver are 0.072 5, 0.044 5, 0.043 0, 0.031 5 and 0.028 2 mGy/MBq, respectively. The organs which have the lowest ab-sorbed doses were brain (0.005 2 mGy/MBq), followed by skin (0.001 1 mGy/MBq), breast (0.001 1 mGy/MBq), heart wall (0.001 2 mGy/MBq) and thyroid (0.001 2 mGy/MBq). The mean absorbed doses for the other major organs ranged from 0.009 5 to 0.023 5 mGy/MBq. The total mean effective dose is 0.019 0 mSv/MBq and the mean effective doses equivalent is 0.025 0 mGy/MBq. A 370-MBq injection of18F-FES leads to an estimated effective dose of 7.03 mSv for the female. There was no statistical difference in the doses results obtained from direct measurement of18F-FES ab-sorption in normal people between previous publications by others and our work.Conclusion:The whole-body mouse imaging can be used as a preclinical tool for initial estimation of the absorbed doses of18F-FES in humans. Furthermore, the potential radiation risk associated with18F-FES imaging is well within the accepted limits.

Skin Doses on the Lens for Temporomandibular Joint Exam in Cone Beam Computed Tomography

ABSTRACT The aim of this study was to evaluate the kerma at the surface of the lens in TMJ CBCT and to derive the equivalent dose. An anthropomorphic phantom of the head and neck manufactured by Radiation Support Devices (model RS-230) was used. The dosimetric measurements were obtained by using fourteen thermoluminescent dosimetry (TLD) dosimeters (LiF: Mg, Ti), divided in two pairs (one pair for each eye) and positioned on the surface of the phantom, per scanner evaluated. The tomographic images were acquired in three types of CBCT equipment (CS 9000, Gendex GXCB 500 and i-CAT). Values of equivalent dose obtained were: 5.82 mSv (CS 9000); 5.38 mSv (Gendex GXCB 500) and 7.98 mSv (i-CAT), which varied in accordance with the scanner and the exposure factors used in the image acquisition. The Gendex GXCB 500 used larger FOV and higher kV, resulting in levels close to those obtained on the CS 9000, while larger doses were associated with the i-CAT. The dose values associated with TMJ radiological procedures should be performed with awareness and appropriateness due to sensitivity of the lens.

Correlations between the irradiated dose to lymph node regions and lymph node recurrence when involved field radiotherapy used for limited-stage small cell lung cancer / 中华放射医学与防护杂志

Objective To analyze the relationship between the radiation doses to mediastinal lymph nodes regions and the regional failure patterns when involved field radiation therapy (IFRT) was used for limited-stage small cell lung cancer (SCLC).Methods The mediastinal lymph node regions (group 1 to 10) of the iimited-stage SCLC patients received definitive radiotherapy were contoured in treatment planning system.The intentional or incidental radiation doses to each lymph node regions were recorded.In-field recurrence,marginal recurrence and out-of-field recurrence were respectively defined as the volume of failed lymph nodes located within the 80％ iso-dose lines,in the 80％-20％ iso-dose lines and beyond the 20％ iso-dose lines of prescribed doses.Results A total of 1 216 lymph node regions in 76 patients were contoured.The median follow-up time was 17.4 months.At diagnosis,lymph node regions with metastatic rates ＞50％ were 4R (68.7％),4L (57.9％),10R (57.9％),2R (56.6％) and 7 (51.3％).The positive lymph node regions were all subjected to prescribed doses.The lymph node regions that received incidental radiation doses of more than 3 000 cGy were:3P,4L,7,6,4R,5,2L.The median lymph node failure-free time was 9.8 months.In this study,only 1 patient developed out-of-field mediastinal lymph nodes failure.The rest of out-of-field recurrences and marginal recurrences were developed in the supraclavicular regions or contralateral hila.Conclusions When IFRT is used to treat mediastinal lymph node regions for patients with SCLC,negative mediastinal regions can be subjected to considerable incidental radiation doses.Out-of-field recurrences of the mediastinal lymph node regions are rare.This is contributed by the incidental radiation dose to these regions.

Radiation physics, quality control, and quality assurance of lung cancer brachytherapy with 125I particles / 中国肿瘤临床

Objective:To improve the therapeutic gain ratio from 125I seed implants by investigating the QA/QC strategies used in brachytherapy treatment of lung cancer. Methods:A total of 287 lung cancer and pulmonary metastases cases were studied. Among which, 184 are male and 103 are female with a mean age of 61.9 years. The NOA-NSCLC subgroup and pulmonary metastases were targeted on conventional CT positioning. Considering that COA-NSCL subgroup on the tumor target area is difficult to determine with CT, the coincidence circuit SPECT was used to assist in positioning. A dose-volume histogram was constructed to evaluate the quality of the TPS and optimization. Corrections on real-time positioning are necessary when using an image-guided implantation. The C-LC should be aligned with the FFB for CT-guided percutaneous puncture implantation. After implantation, dosimetry verification was con-ducted. Results:The NOA-NSCLC subgroup, comprising the risk organs such as heart, lung, and spinal column, received an average dose of 137, which was significantly lower than that of normal tissue dose tolerance. The NOA-NSCLC subgroup and lung metastases have matched peripheral dosages of 92.1 and 106.2 Gy with local-control efficiency rates of 91.97% (126/137) and 96.0% (48/50), 1-year survival rates of 91.24%and 83.4%(42/50), and 2-year survival rates of 50.36%(69/137) and 52.3%(26/50), respectively. The 35 COA-NSCL subgroup and 65 lung cancer group have local control efficiency rates of 91.43%(32/35) and 92.3%(60/65) and 1-year survival rates of 88.57%(31/35) and 80.30%(53/66), respectively. Conclusion:Proper radiation dosimetry as a QA/QC strategy was found to improve particle-implantation therapy gain and greatly reduce the risks of radiation pneumonia and pulmonary fibrosis.

Dosimetric evaluation of Tomotherapy and four-box field conformal radiotherapy in locally advanced rectal cancer

PURPOSE: To report the results of dosimetric comparison between intensity-modulated radiotherapy (IMRT) using Tomotherapy and four-box field conformal radiotherapy (CRT) for pelvic irradiation of locally advanced rectal cancer. MATERIALS AND METHODS: Twelve patients with locally advanced rectal cancer who received a short course preoperative chemoradiotherapy (25 Gy in 5 fractions) on the pelvis using Tomotherapy, between July 2010 and December 2010, were selected. Using their simulation computed tomography scans, Tomotherapy and four-box field CRT plans with the same dose schedule were evaluated, and dosimetric parameters of the two plans were compared. For the comparison of target coverage, we analyzed the mean dose, V(n Gy), D(min), D(max), radical dose homogeneity index (rDHI), and radiation conformity index (RCI). For the comparison of organs at risk (OAR), we analyzed the mean dose. RESULTS: Tomotherapy showed a significantly higher mean target dose than four-box field CRT (p = 0.001). But, V(26.25 Gy) and V(27.5 Gy) were not significantly different between the two modalities. Tomotherapy showed higher D(max) and lower D(min). The Tomotherapy plan had a lower rDHI than four-box field CRT (p = 0.000). Tomotherapy showed better RCI than four-box field CRT (p = 0.007). For OAR, the mean irradiated dose was significantly lower in Tomotherapy than four-box field CRT. CONCLUSION: In locally advanced rectal cancer, Tomotherapy delivers a higher conformal radiation dose to the target and reduces the irradiated dose to OAR than four-box field CRT.

Are Medical Personnel Safe from Radiation Exposure from Patient Receiving Radioiodine Ablation Therapy? / 핵의학분자영상

Radioiodine ablation therapy has been considered to be a standard treatment for patient with differentiated thyroid cancer after total thyroidectomy. Patients may need to be hospitalized to reduce radiation exposure of other people and relatives from radioactive patients receiving radioiodine therapy. Medical staffs, nursing staffs and technologists sometimes hesitate to contact patients in radioiodine therapy ward. The purpose of this paper is to introduce radiation dosimetry, estimate radiation dose from patients and emphasize the safety of radiation exposure from patients treated with high dose radioiodine in therapy ward. The major component of radiation dose from patient is external exposure. However external radiation dose from these patients treated with typical therapeutic dose of 4 to 8 GBq have a very low risk of cancer induction compared with other various risks occurring in daily life. The typical annual radiation dose without shielding received by patient is estimated to be 5 to 10 mSv, which is comparable with 100 to 200 times effective dose received by chest PA examination. Therefore, when we should keep in mind the general principle of radiation protection, the risks of radiation exposure from patients are low and the medical personnel are considered to be safe from radiation exposure.

Quality Control of Radiation Dosimetry Service / 의학물리

We have developed standards based on international criterions for the quality control of dose tested by the measurement institutions of individual exposure doses through improving the reliability of data on the exposure dose of individuals working in radioactive environment and securing the accuracy and reliability of individual dose measurements. Laws related to radiation dose applied to domestic institutions refer to ANSI N13.11?1993, but currently , in U.S. and some other countries the measurement of radiation doses is based on ANSI N13.11?2001 that reduced test categories and tightened the standards. We made efforts to simplify the standards and to reduce the number of dosimeters required in experiment, and avoided preventing or hindering the use of future technologies not approved under the current law such as glass dosimeter and optical stimulation dosimeter. The Quality Management Manual of Radiation Dosimetry Service, Assessment Manual of Radiation Dosimetry Service Accreditation Program, and the Personnel Dosimetry Performance-Criteria for Testing are documents applicable in supervising laboratories.

Medical Application of Radiation Internal Dosimetry / 핵의학분자영상

Medical internal radiation dosimetry (MIRD) is an important part of nuclear medicine research field using therapeutic radioisotope. There have been many researches using MIRD for the development of new therapeutic approaches including radiopharmaceutical, clinical protocol, and imaging techniques. Recently, radionuclide therapy has been re-focused as new solution of intractable diseases, through to the advances of previous achievements. In this article, the basic concepts of radiation and internal radiation dosimetry are summarized to help understanding MIRD and its application to clinical application.

Comparison of cone beam CT and conventional CT in absorbed and effective dose / 대한구강악안면방사선학회지

PURPOSE: This study provides comparative measurements of absorbed and effective doses for newly developed cone beam computed tomography (CT) in comparison with these doses for conventional CT. MATERIALS AND METHODS: Thermoluminescent dosimeter rods (TLD rod: GR-200, Thermo Fisher Scientific Inc., Waltham, MA, USA) were placed at 25 sites throughout the layers of Male ART Head and Neck Phantom (Radiology Support Devices Inc., Long Beach, USA) for dosimetry. Implagraphy, DCT Pro (Vatech Co., Hwasung, Korea) units, SCT-6800TXL (Shimadzu Corp., Kyoto, Japan), and Cranex 3+ (Soredex Orion Corp., Helsinki, Finland) were used for radiation exposures. Absorption doses were measured with Harshaw 3500TLD reader (Thermo Fisher Scientific Inc., Waltham, MA, USA). Radiation weighted doses and effective doses were measured and calculated by 2005 ICRP tissue weighting factors. RESULTS: Absorbed doses in Rt. submandibular gland were 110.57 mGy for SCT 6800TXL (Implant), 24.56 mGy for SCT 6800TXL (3D), 22.39 mGy for Implagraphy3, 7.19 mGy for DCT Pro, 5.96 mGy for Implagraphy1, 0.70 mGy for Cranex 3+. Effective doses (E2005draft) were 2.551 mSv for SCT 6800TXL (Implant), 1.272 mSv for SCT 6800TXL (3D), 0.598 mSv for Implagraphy3, 0.428 mSv for DCT Pro and 0.146 mSv for Implagraphy1. These are 108.6, 54.1, 25.5, 18.2 and 6.2 times greater than panoramic examination (Cranex 3+) doses (0.023 mSv). CONCLUSION: Cone beam CT machines recently developed in Korea, showed lower effective doses than conventional CT. Cone beam CT provides a lower dose and cost alternative to conventional CT, promising to revolutionize the practice of oral and maxillofacial radiology.

Radiation Exposure to Physicians in the Emergency Department

PURPOSE: Emergency physicians (EP) are vulnerable to radiation exposure while on duty in the emergency department (ED). Although many studies have been reported abroad, there have been few studies of radiation exposure to EP in Korea. This study was performed to determine the present radiation exposure conditions of EP in Korea. METHODS: A prospective study was conducted from April 1, 2007 to June 30, 2007 at ED in three teaching hospitals. Eighteen interns and 19 residents were selected. Each wore thermoluminescent personal radiation dosimetry monitors at near the thyroid while working in the ED. We estimated the radiation exposure dose of these EP for three months and compared the results with those obtained for radiologists. RESULTS: The average radiation exposure dose of EP over three months was 0.257+/-0.391 mSv, and that of radiologists was 0.184+/-0.273 mSv. These results were below the recommended occupational dose limit of 5 mSv per 3 months. The radiation exposure dose of EP was higher than that of radiologists, but the difference was not statistically significant (0.280+/-0.303 vs 0.075+/-0.981 mSv, p=0.042). CONCLUSION: We recommend that the use of dosimetry by EP needs to be reviewed. EP should be aware of radiation exposure risks and minimize radiation exposure.

Internal Radiation Dosimetry using Nuclear Medicine Imaging in Radionuclide Therapy / 핵의학분자영상

Radionuclide therapy has been an important field in nuclear medicine. In radionuclide therapy, relevant evaluation of internally absorbed dose is essential for the achievement of efficient and sufficient treatment of incurable disease, and can be accomplish by means of accurate measurement of radioactivity in body and its changes with time. Recently, the advances of nuclear medicine imaging and multi?modality imaging processing techniques can provide chance of more accurate and easier measurement of the measures commented above, in cooperation of conventional imaging?based approaches. In this review, basic concept for internal dosimetry using nuclear medicine imaging is summarized with several check points which should be considered in real practice.

Internal Radiation Dosimetry using Nuclear Medicine Imaging in Radionuclide Therapy / 핵의학분자영상

Radionuclide therapy has been an important field in nuclear medicine. In radionuclide therapy, relevant evaluation of internally absorbed dose is essential for the achievement of efficient and sufficient treatment of incurable disease, and can be accomplish by means of accurate measurement of radioactivity in body and its changes with time. Recently, the advances of nuclear medicine imaging and multi?modality imaging processing techniques can provide chance of more accurate and easier measurement of the measures commented above, in cooperation of conventional imaging?based approaches. In this review, basic concept for internal dosimetry using nuclear medicine imaging is summarized with several check points which should be considered in real practice.

Internal Radiation Dosimetry in Radionuclide Therapy / 핵의학분자영상

Radionuclide therapy has been continued for treatment of incurable diseases for past decades. Relevant evaluation of absorbed dose in radionuclide therapy is important to predict treatment output and essential for making treatment planning to prevent unexpected radiation toxicity. Many scientists in the field related with nuclear medicine have made effort to evolve concept and technique for internal radiation dosimetry. In this review, basic concept of internal radiation dosimetry is described and recent progress in method for dosimetry is introduced.