Patient doses in gamma-intracoronary radiotherapy: the Radiation Burden Assessment Study

PURPOSE: To determine accurately the radiation burden of both patients and staff from intracoronary radiotherapy (IRT) with (192)Ir and to investigate the importance of IRT in the patient dose compared with interventional X-rays. METHODS AND MATERIALS: The Radiation Burden Assessment Study (RABAS) population consisted of 9 patients undergoing gamma-IRT after percutaneous transluminal coronary angioplasty and 14 patients undergoing percutaneous transluminal coronary angioplasty only as the control group. For each patient, the dose to the organs and tissues from the internal and external exposure was determined in detail by Monte Carlo N-particle simulations. Patient skin dose measurements with thermoluminescence dosimeters served as verification. Staff dosimetry was performed with electronic dosimeters, thermoluminescence dosimeters, and double film badge dosimetry. RESULTS: With respect to the patient dose from IRT, the critical organs are the thymus (58 mGy), lungs (31 mGy), and esophagus (27 mGy). The mean effective dose from IRT was 8 mSv. The effective dose values from interventional X-rays showed a broad range (2-28 mSv), with mean values of 8 mSv for the IRT patients and 13 mSv for the control group. The mean dose received by the radiotherapist from IRT was 4 microSv/treatment. The doses to the other staff members were completely negligible. CONCLUSION: Our results have shown that the patient and personnel doses in gamma-IRT remain at an acceptable level. The patient dose from IRT was within the variations in dose from the accompanying interventional X-rays.     

Quantitative bone single-photon emission computed tomography for prediction of pain relief in metastatic bone disease treated with rhenium-186 etidronate.

PURPOSE: To calculate radiation doses of rhenium-186 ((186)Re) etidronate in painful bone metastases using quantitative bone single-photon emission computed tomography (SPECT) and to determine the threshold dose for predicting pain relief. We also wanted to determine whether technetium-99m ((99m)Tc) methylene diphosphonate (MDP) concentrations predict radiation doses of (186)Re etidronate in painful lesions. MATERIALS AND METHODS: Forty-eight patients with breast and prostate cancer were evaluated. Patients received therapeutic doses of (186)Re etidronate. The area under the pain over time curve (AUPC) was measured for 8 weeks after treatment. Response was calculated as the percentage of change in AUPC. Quantitative bone SPECT (QBS)-measured concentration of (186)Re etidronate was used for calculating radiation doses. Receiver operating characteristics curve analysis determined the radiation dose threshold that best separated responders from nonresponders. SPECT-measured concentration of (186)Re etidronate in the urinary bladder was correlated with its concentration in the voided urine. Concentration of (99m)Tc MDP was compared with radiation doses to painful metastases. RESULTS: The radiation dose threshold was 2.10 Gy. For a decrease of 50% in the AUPC, the positive predictive value (PPV) of this value was 75% and the negative predictive value (NPV) was 88%. For a decrease in pain of 33%, the PPV was 84% and the NPV was 81%. In prostate cancer patients only, the PPV was 81% and the NPV was 92%. The correlation between in vivo/in vitro measured urine concentration was 0.90. The correlation between (99m)Tc MDP concentration and radiation doses of (186)Re etidronate was 0.92. CONCLUSION: QBS-measured radiation doses of (186)Re etidronate in painful metastases are a good predictor of pain relief. Bone SPECT using (99m)Tc MDP predicts radiation doses delivered by (186)Re etidronate.     

Chemoradionuclide therapy with 186re-labeled liposomal doxorubicin: toxicity, dosimetry, and therapeutic response

This study was performed to determine the maximum tolerated dose (MTD) and therapeutic effects of rhenium-186 ((186)Re)-labeled liposomal doxorubicin (Doxil), investigate associated toxicities, and calculate radiation absorbed dose in head and neck tumor xenografts and normal organs. Doxil and control polyethylene glycol (PEG)-liposomes were labeled using (186)Re-N,N-bis(2-mercaptoethyl)-N',N'-diethylethylenediamine (BMEDA) method. Tumor-bearing rats received either no therapy (n=6), intravenous Doxil (n=4), or escalating radioactivity of (186)Re-Doxil (185-925?MBq/kg) or (186)Re-PEG-liposomes (1110-1665?MBq/kg) and were monitored for 28 days. Based on body weight loss and systemic toxicity, MTD for (186)Re-Doxil and (186)Re-PEG-liposomes were established at injected radioactivity/body weight of 740 and 1480?MBq/kg, respectively. (186)Re-injected radioactivity/body weight for therapy studies was determined to be 555?MBq/kg for (186)Re-Doxil and 1295?MBq/kg for (186)Re-PEG-liposomes. All groups recovered from their body weight loss, leucopenia, and thrombocytopenia by 28 days postinjection. Normalized radiation absorbed dose to tumor was significantly higher for (186)Re-Doxil (0.299±0.109 Gy/MBq) compared with (186)Re-PEG-liposomes (0.096±0.120 Gy/MBq) (p<0.05). In a separate therapy study, tumor volumes were significantly smaller for (186)Re-Doxil (555?MBq/kg) compared with (186)Re-PEG-liposomes (1295?MBq/kg) (p<0.01) at 42 days postinjection. In conclusion, combination chemoradionuclide therapy with (186)Re-Doxil has promising potential, because good tumor control was achieved with limited associated toxicity.     

Abdominal pediatric cancer surveillance using serial computed tomography: evaluation of organ absorbed dose and effective dose

Computed tomography (CT) is used extensively in cancer diagnosis, staging, evaluation of response to treatment, and in active surveillance for cancer reoccurrence. A review of CT technology is provided, at a level of detail appropriate for a busy clinician to review. The basis of x-ray CT dosimetry is also discussed, and concepts of absorbed dose and effective dose (ED) are distinguished. Absorbed dose is a physical quantity (measured in milligray [mGy]) equal to the x-ray energy deposited in a mass of tissue, whereas ED uses an organ-specific weighting method that converts organ doses to ED measured in millisieverts (mSv). The organ weighting values carry with them a measure of radiation risk, and so ED (in mSv) is not a physical dose metric but rather is one that conveys radiation risk. The use of CT in a cancer surveillance protocol was used as an example of a pediatric patient who had kidney cancer, with surgery and radiation therapy. The active use of CT for cancer surveillance along with diagnostic CT scans led to a total of 50 CT scans performed on this child in a 7-year period. It was estimated that the patient received an average organ dose of 431 mGy from these CT scans. By comparison, the radiation therapy was performed and delivered 50.4 Gy to the patient's abdomen. Thus, the total dose from CT represented only 0.8% of the patient's radiation dose.     

基于小鼠全身动态PET扫描估算16α-18F-17β-雌二醇的人体内辐射剂量

背景与目的：由小鼠全身动态PET显像数据获得药物在小鼠体内的生物分布,利用器官内剂量评估/指数模型分析软件(organ level inter dose assessment/exponential model,OLINDA/EXM)估算18F-fluo-roestradiol,18F-FES)在人体内的吸收剂量、全身有效剂量和有效剂量当量。方法：健康雌性KM小鼠尾静脉注射18F-FES后行160 min动态PET采集,经3D-OSEM/MAP算法重建获得PET图像。再行高分辨率CT显像,在PET/CT融合图像上,选取各脏器勾画感兴趣体积(volume of interest,VOI),获得相应时间-活度曲线和其曲线下面积、滞留时间、成年女性体模对应各器官的滞留时间。依据美国核医学会医用内照射剂量学委员会提出的内照射剂量计算方法(MIRD体系),利用OLINDA/EXM软件计算18F-FES在人体内的吸收剂量、全身有效剂量和有效剂量当量。最后所得数据与已公开发表计算18F-FES内照射剂量的文献数据行配对t检验,验证本文方法的有效性。结果：人体内胆囊壁、膀胱壁、小肠、上部大肠和肝脏的吸收剂量最高,分别为0.0725、0.0445、0.0430、0.0315和0.0282 mGy/MBq。大脑、皮肤、乳腺、心脏壁和甲状腺吸收剂量最低,分别为0.0052、0.0011、0.0012、0.0012和0.0013 mGy/MBq。对放射性敏感的器官如骨原细胞、胸腺和红骨髓的吸收剂量均较低,范围为0.0014~0.0218 mGy/MBq。全身平均吸收剂量为0.0147 mGy/MBq,全身有效剂量当量为0.0250 mGy/MBq,全身有效剂量为0.0190 mSv/MBq。对于常规注射185 MBq18F-FES,人体有效剂量为3.5150 mSv。与直接测量18F-FES在健康人体各主要脏器内吸收剂量的文献行配对t检验,差异无统计学意义(t=1.478,P=0.153)。结论：利用OLINDA/EXM软件根据小鼠全身动态PET/CT数据可有效估算18F-FES在人体内的吸收剂量和有效剂量。18F-FES可安全地用于人体,其有效剂量低于允许范围上限。该研究可为临床放心使用18F-FES提供依据。     

99m Tc-HYNIC-TOC人体内照射剂量研究

背景与目的：放射性显像药物在人体内的剂量分布、各器官的吸收剂量及全身有效剂量数据非常重要。研究^99mTc标记的经肼基烟酰胺修饰的奥曲肽（^99mTc-Hydrazinonicotinyl-Tyr3-Octreotide,^99mTc-HYNIC-TOC）在人体内各器官的吸收剂量、全身吸收剂量及全身有效剂量。方法：对2018年5—6月复旦大学附属肿瘤医院收治的5例神经内分泌肿瘤患者静脉注射370 MBq^99mTc-HYNIC-TOC后于0.5、1.0、2.0、4.0和8.0 h行全身平面采集,其中2.0 h平面采集后即刻行全身断层采集。断层数据经迭代重建后,将数据导入GE Dosimetry Toolkit处理,在单光子发射计算机断层显像（single photon emission computedtomography,SPECT）/CT融合图像上勾画各器官生成感兴趣区（region of interest,ROI）,获得相应时间-活度曲线并计算曲线下面积得到滞留时间。依据美国核医学会医用内照射剂量学（Medical Internal Radiation Dose,MIRD）委员会提出的内照射剂量计算方法（MIRD体系）,利用OLINDA/EXM软件计算^99mTc-HYNIC-TOC在人体内各器官的吸收剂量、全身吸收剂量和全身有效剂量。结果：脾脏、膀胱、肾脏的单位活度吸收剂量较高,男性分别为0.042、0.019和0.016 mGy/MBq,女性分别为0.026、0.027和0.017 mGy/MBq。大脑、皮肤、甲状腺的单位活度吸收剂量较低,男性分别为0.000 3、0.000 5和0.000 5 mGy/MBq,女性分别为0.000 3、0.000 5和0.000 6 mGy/MBq。对放射线敏感的器官如骨原细胞、胸腺和红骨髓的单位活度吸收剂量均较低,范围为0.001 2~0.002 2 mGy/MBq。全身平均单位活度吸收剂量男性为0.001 7 mGy/MBq,女性为0.0016 mGy/MBq。全身单位活度有效剂量男性为0.004 58 mSv/MBq,女性为0.004 55 mSv/MBq。结论：^99mTc-HYNIC-TOC可安全地用于人体,其有效剂量低于允许范围上限。该研究结果可为临床安全使用^99mTc-HYNIC-TOC提供依据,也为其他放射性药物的安全性评估和加快临床转化提供新的可行方案。     

Radiosynoviorthesis of knees by means of 166Ho-holmium-boro-macroaggregates

The aim of this study was to evaluate adverse and therapeutic effects of applicated holmium-boro-macroaggregates (HBMAs) in the radiosynoviorthesis (RSO) of knees in patients suffering from chronic synovitis. We started RSO of the knees by means of a new radiopharmaceutical (RF) HBMA in patients with gonarthrosis, rheumatoid arthritis, chronic synovitis, psoriatic arthritis, and gout arthropathy. Seventeen (17) intra-articular injections were performed in 15 patients who were receiving a mean activity of 972 MBq (range, 904-1057) of 166Ho-HBMA. Patient inclusion to the study followed a series of inclusion and exclusion criterions. The patients were hospitalized for 3 days. Side-effects were evaluated during their hospital stay and again after 6-8 weeks. Static scintigraphy of knee joints and measurements of blood radioactivity were performed. Therapeutic effects were evaluated after 6-8 weeks and at 6 months. In 2 hours and 2 days following the application, we proved, by means of knee and inguinal scintigraphy, only insignificant radiopharmaceutical leakage from the joint cavity to the inguinal lymph nodes in 4 patients. In the treated patients, no serious adverse effects occurred. Nine (9) patients were without complaints, 4 patients had slight knee exudation, and 2 patients had great exudation. Therapeutic effects were as follows: 2 patients were without pain, 9 were with lower pain, 3 were with the same pain, and 1 patient was with increased pain. Joint motion was improved in 7 patients, remained the same in 7 patients, and was impaired in 1 patient. Analgesics consumption was lower in 5 patients, the same in 9 patients, and greater in 1 patient. Knee exudation was absent in 2 patients, lower in 4 patients, the same in 6 patients, and greater in 3 patients. In 3 patients it was necessary to do surgical RSO. This RF can extend the range of clinically used radiopharmaceuticals for RSO and to supplement space between 90Y with high energy and 186Re with 169Er with lower beta energy. The energy of 166Ho is suitable for great and medium joints (i.e., knees, hips, shoulders, elbows, wrists, and ankles).     

Long-term biokinetics and radiation exposure of patients undergoing 14C-glycocholic acid and 14C-xylose breath tests

The (14)C-glycocholic acid and (14)C-xylose breath tests are clinically used for the diagnosis of intestinal diseases, such as bacterial overgrowth in the small intestine. The two tests have in earlier studies been thoroughly evaluated regarding their clinical value, but due to the long physical half-life of (14)C and the limited biokinetic and dosimetric data, which are available for humans, several hospitals have been restrictive in their use. The aim of this study was to investigate the long-term biokinetics and dosimetry of the two (14)C compounds in patients and volunteers, using the highly sensitive accelerator mass spectrometry (AMS) technique. Eighteen (18) subjects were included, 9 for each compound. The (14)C content in samples from exhaled air, urine, and, for some subjects, also feces were analyzed with both liquid scintillation counting (LSC) and AMS. The results from the glycocholic acid study showed that, up to 1 year after the administration, 67%+/-6% (mean+/-standard deviation) of the administered activity was recovered in exhaled air, 2.4%+/-0.4% was found in urine, and 7.6% (1 subject) in feces. In the xylose study, the major part was found in the urine (66%+/-2%). A significant part was exhaled (28%+/-5%), and the result from an initial 72-hour stool collection from 2 of the subjects showed that the excretion by feces was insignificant. The absorbed dose to various organs and tissues and the effective dose were calculated by using biokinetic models, based on a combination of experimental data from the present study and from earlier reports. In the glycocholic acid study, the highest absorbed dose was received by the colon (1.2 mGy/MBq). In the xylose study, the adipose tissue received 0.8 mGy/MBq. The effective dose was estimated to 0.5 (glycocholic acid) and 0.07 mSv/MBq (xylose). Thus, from a radiation protection point of view, we see no need for restrictions in using the two (14)C-labeled radiopharmaceuticals on adults with the activities normally administered (0.07-0.4 MBq).     

Radioisotopic methods of studying the pelvic lymphatic system in patients with cancer of the cervix and corpus uteri]

An original method of studying the functional state of the lymphatic system-lymphotachoradiography, elaborated in the Institute of Experimental and Clinical Oncology of the USSR Acadeny of Medical Sciences, was found to be rather effective in estimating metastatic spread of the uterine cervix and body cancer. The coefficients of phagocytosis of colloid particles by lymphoid tissue are determined. Normal coefficients are equal for inguinal, iliac and paraaortic groups of lymph nodes to 1.60+/-0.05; 1.40+/-+/-0.04; 1.10+/-0.10 accordingly. In some pathological changes in lymph nodes these coefficients are changed: 0.41+/-0.01; 0.48+/-0.01; 0.24+/-0.05, correspondingly.     

Radiosynovectomy in hemophilic synovitis: correlation of therapeutic response and blood-pool changes

AIM: The aim of this study was to evaluate the efficacy of 90Y and 186Re radiosynovectomy in patients with hemophilic synovitis. METHODS: Radiosynovectomy was performed in 32 joints of 20 patients with hemophilic synovitis by using 90Y citrate colloid in the knee and 186Re sulfide colloid in the elbow, shoulder, and ankle. The indication for radiosynovectomy was the continuous presence of intra-articular blood or effusion and three or more hemorrhages into the same joint within the last 6 months. Response to therapy was first assessed at the 4th month with blood-pool imaging. Patients were followed up by clinical evaluation based on assessments of joint-bleeding frequency, using range of motion measurements at 6-month intervals for an average of 1 year (range, 9-15 months). RESULTS: A marked decrease (an 80%-100% decrease) in bleeding episodes was seen in 24 of 32 (75%) joints, a moderate decrease (51%-79% decrease) in 1 (9%) joint, and a mild decrease (30%-50%) in 3 (13%) joints. Frequency of intra-articular bleeding after treatment was unchanged in only 13% of the joints. The number of hemarthroses significantly decreased after therapy (p < 0.05). The mean bleeding frequency of the joints were 1.7 +/- 0.9 and 0.3 +/- 0.7 per month before and after therapy, respectively. The ratios of joints which had marked improvement after therapy were 86% in the ankle, 73% in the elbow, and 58% in the knee. There was no significant difference between percent joint range of motion limitations measured before and after therapy (p > 0.05). The correlation between therapeutic outcome (in terms of joint bleeding) and the difference of pre- and posttherapeutic blood-pool indices were significant (r = 0.594; p < 0.05), while the correlation between therapeutic outcome and pretherapeutic radiologic scale and pretherapeutic blood-pool indices were not significant (r = 0.095; p > 0.05; r = -0.089; p > 0.05, respectively). CONCLUSION: Radiosynovectomy is a simple but quite effective and efficient procedure in limiting the frequency of joint hemorrhage in patients with hemophilia. Blood-pool imaging may be an objective means for monitoring therapy response in these patients.     

Significantly Low Effective Dose from 18FDG PET/CT Scans Using Dose Reducing Strategies: "Lesser is Better"

Background: Fluorodeoxyglucose (18FDG) PET/CT imaging has become an important component of the management paradigm in oncology. However, the significant imparted radiation exposure is a matter of growing concern especially in younger populations who have better odds of survival. The aim of this study was to estimate the effective dose received by patients having whole body 18FFDG PET/CT scanning as per recent dose reducing guidelines at a tertiary care hospital. Materials and Methods: This prospective study covered 63 patients with different cancers who were referred for PET/CT study for various indications. Patients were prepared as per departmental protocol and 18FDG was injected at 3 MBq/Kg and a low dose, nonenhanced CT protocol (LD NECT) was used. Diagnostic CT studies of specific regions were subsequently performed if required. Effective dose imparted by 18FDG (internal exposure) was calculated by using multiplying injected dose in MBq with coefficient 1.9?102 mSv/MBq according to ICRP publication 106. Effective dose imparted by CT was calculated by multiplying DLP (mGy.cm) with ICRP conversion coefficient "k" 0.015 [mSv / (mG. cm)]. Results: Mean age of patients was 49 18 years with a male to female ratio of 35:28 (56%:44%). Median dose of 18FDG given was 194 MBq (range: 139293). Median CTDIvol was 3.25 (2.46.2) and median DLP was 334.95 (246.70 576.70). Estimated median effective dose imparted by 18FDG was 3.69 mSv (range: 2.855.57). Similarly the estimated median effective dose by low dose (nondiagnostic) CT examination was 4.93 mSv (range: 2.14 10.49). Median total effective dose by whole body 18FDG PET plus low dose nondiagnostic CT study was 8.85 mSv (range: 5.5613.00). Conclusions: We conclude that the median effective dose from a whole body 18FDG PET/CT in our patients was significantly low. We suggest adhering to recently published dose reducing strategies, use of ToF scanner with CT dose reducing option to achieve the lower if not the lowest effective dose. This would certainly reduce the risk of second primary malignancy in younger patients with higher odds of cure from first primary cancer.     

Distribution and depth of internal mammary lymph nodes in breast cancer

Lymphoscintigraphy was performed in 50 cases of breast cancer using 99mTc-colloid as a tracer. The results indicated that 277 lymph nodes, 128 on the right side and 149 on the left, were imaged. Most of the lymph nodes were located in the second and third intercostal spaces. The mean distance between these lymph nodes and mid line was 1.93 +/- 1.05 cm-2.70 +/- 0.93 cm. The mean depth was 2.42 +/- 0.52 cm-3.07 +/- 0.72 cm. It was over 4.0 cm in isolated cases. The lymph nodes which were not showed after repeated examination could have been involved by the cancer. Radionuclide lymphoscintigraphy, being safe, easily repeated and having low radiation dose and good image, is very useful for radiotherapy.     

鼻咽癌放射治疗后颈部淋巴结复发原因分析

目的 :探讨鼻咽癌放射治疗后颈部淋巴结复发原因及其特点。方法 :回顾性分析了 1994年 11月～ 2 0 0 1年 9月因鼻咽癌放射治疗后颈部淋巴结复发而行颈淋巴结清除的 69例患者的临床资料。结果 :鼻咽癌放疗后颈部淋巴结复发时间平均为 3 4 5个月( 6 5～ 2 42 5个月 ) ,其与治疗前N分期和照射剂量相关 ,联合化疗不能提高颈部淋巴结的控制率。结论 :鼻咽癌放疗后颈部淋巴结复发大多发生在 2年内 ,早期诊断和提高颈部照射剂量有可能提高颈部控制率 ,而联合化疗无效     

Radiation dose in computed tomography of the pelvis: Comparison of helical and axial scanning

An anthropomorphic Rando phantom was used to compare radiation doses sustained during helical and conventional axial CT of the pelvis. The values obtained with the Rando phantom were validated against cadaveric phantoms, and show good agreement. For the authors’particular CT unit, helical scanning was found to deliver a lower radiation dose than conventional axial scanning. This was most prominent at 1.0-s tube rotation times (average dose ratio 1.24). For realistic scanning parameters and exposure factors, the ratio of radiation dose to pelvic organs can be expected to lie in the range of 40-100 mGy. The whole-body effective dose (ED) depends on selection of scanning parameters and patient anatomy. In a favourable case scenario, the ED for CT scanning of the pelvis in a male can be expected to be between 10 and 20 mSv if the scrotum is not included in the radiation field, while the ED in a female will be ?20 mSv. An examination of scatter radiation fall-off curves from a single slice shows that the spread of scatter radiation is only marginally affected by slice thickness. A total of 10-12 cm of human soft tissue acts as a good barrier against internal scattered radiation. The use of such scatter fall-off curves, together with manufacturers’dosimetry specifications, allows a fast estimate of absorbed dose.     

Diagnostic imaging for suspected pulmonary embolism during pregnancy and postpartum: A comparative radiation dose study

Introduction

To compare the radiation dose exposure and diagnostic efficiency of computed tomographic pulmonary angiography (CTPA) and ventilation/perfusion imaging (V/Q) for clinically suspected pulmonary embolism (PE) in pregnant and postpartum women in a tertiary hospital setting.

Methods

A retrospective cohort study of 473 pregnant and postpartum women referred for CTPA or V/Q for clinically suspected PE between January 2013 and December 2018 at a tertiary hospital. Maternal effective radiation dose, breast-absorbed radiation dose and fetal-absorbed dose estimates were calculated. Diagnostic yield was evaluated from radiological findings.

Results

Computed tomographic pulmonary angiography (CTPA) was more commonly used for the imaging of suspected PE in pregnant and postpartum populations (51.9% vs. 48.1% and 77.1% vs. 22.9%, respectively). CTPA was associated with higher maternal effective and breast-absorbed doses (maternal effective CTPA 4.7 (±2.9) mSv (millisievert), V/Q 1.7(±0.8) mSv (mean difference 2.93 mSv P < 0.001), and breast-absorbed CTPA 8.0 (±5.2) mGy (milligray), V/Q 0.3 (±0.1) (mean difference 7.67 mGy P < 0.001), respectively). Fetal radiation dose exposure was low. The incidence of positive PE was 5.5%. Indeterminate rates of CTPA and V/Q were 3.0% and 5.5% (P = 0.176), respectively.

Conclusions

Compared to V/Q, CTPA is associated with higher maternal and breast radiation dose; however, modern CT scanners achieve lower radiation doses than historically described. Fetal radiation dose was comparably low. The diagnostic yield of the imaging modalities in pregnant and postpartum women is similar. Revision of guidelines should occur with the advances in CT technology.     

Use of lymphoscintigraphy in radiation treatment of primary breast cancer in the context of lymphedema risk reduction

Purpose

The goal of this study was to determine the feasibility of SPECT/CT scintigraphic method for mapping lymphatic drainage for radiation therapy of breast cancer.

Materials and methods

Thirty-six patients were enrolled in a SPECT/CT lymphoscintigraphy study. ^99mTc sulfur colloid (1 mCi) was injected intradermally in the ipsilateral arm. After 5–8 h post-injection, the SPECT/CT scans were taken and analyzed on a GE eNTRGRA system. The SPECT/CT images were co-registered in the treatment planning system (TPS). The original treatment plan was recreated for nodal dosimetry. Intensity modulated radiation therapy (IMRT) planning was performed for reducing lymph node dose for reducing arm lymphedema.

Results

The number of lymph nodes varied from 0 to 10 with a mean value of 3.4 ± 5.4 nodes. The location of nodes varied in the axillary, supraclavicular, and breast regions depending upon the surgical procedure and the extent of the disease. The prescribed radiation dose to the breast varied from 45 to 50.4 Gy depending on the disease pattern in 32 evaluated patients having CT data. The dose to lymph nodes varied from 0 to 61.8 Gy depending upon the location and the radiation technique used. SPECT/CT study in conjunction with IMRT plan showed that it is possible to decrease nodal dose and thereby potentially reduce the risk of developing arm lymphedema.

Conclusions

The SPECT/CT device provides a novel method to map the lymph nodes in the radiation treatment fields that could be used to tailor the radiation dose.     

Low-dose CT protocols for guiding radiofrequency ablation for the treatment of small renal cell carcinomas

Objective: Computed tomography (CT)-guided radiofrequency ablation (RFA) results in a high radiation dose. This study aimed to assess low-dose CT protocols for guiding RFA and oncologic outcomes for the treatment of small renal cell carcinoma (RCC).

Materials and methods: Between December 2011 and December 2014, CT-guided RFA was performed in 31 patients with 31 biopsy-proven RCCs (median, 2.1?cm). RFA included planning, targeting, monitoring and survey phases. The dose length product (DLP), CT dose index volume (CTDIvol), effective dose, number of scans, scan range, tube current and exposure time of RFA phases were compared. The 3-year recurrence-free survival rate was recorded. Nonparametric or parametric repeated-measures ANOVA with Dunn’s or Tukey–Kramer multiple comparisons and Kaplan–Meier analysis were used for statistical analysis.

Results: The median total DLP, CTDIvol and effective dose of CT-guided RFA procedures per session were 1238.8 mGy (range 517.4–3391.7 mGy), 259.7 mGy (10.7–67.9 mGy) and 18.6 mSv (7.8–50.9 mSv), respectively. The median DLP, CTDIvol, effective dose, number of scans, tube current and exposure time during the targeting phase were higher than those during the other phases (p?p?>?0.05) but smaller than those in the planning and survey phases (p?Conclusions: Low-dose CT protocols for guiding RFA may reduce radiation dose without compromising oncologic outcomes. Reducing the number of scans during the targeting phase contributes to dose reduction.     

Pretargeted radioimmunotherapy (PRIT) for treatment of non-Hodgkin's lymphoma (NHL): initial phase I/II study results

Pretargeted radioimmunotherapy (PRIT) was investigated in patients with non-Hodgkin's lymphoma (NHL). The PRIT approach used in this study is a multi-step delivery system in which an antibody is used to target streptavidin to a tumor associated antigen receptor, and subsequently biotin is then used to target 90Y radioisotope to the tumor localized streptavidin. A chimeric, IgG1, anti-CD20 antibody, designated C2B8 or Rituximab, was conjugated to streptavidin (SA) and administered to patients with NHL. Thirty-four hours later, a clearing agent, synthetic biotin-N-acetyl-galactosamine, was administered to remove non-localized conjugate from the circulation. Finally, a DOTA-biotin ligand, labeled with 111In for imaging and/or 90Y for therapy was administered. Ten patients with relapsed or refractory NHL were studied. In three patients, the C2B8/SA conjugate was radiolabeled with a trace amount of 186Re in order to assess pharmacokinetics and biodistribution using gamma camera imaging. Seven patients received 30 or 50 mCi/m2 90Y DOTA-biotin. Re-186 C2B8/SA images confirmed that the conjugate localized to known tumor sites and that the clearing agent removed > 95% of the conjugate from the circulation. Radiolabeled biotin localized well to tumor. Unbound radiobiotin was rapidly excreted from the whole body and normal organs. The mean tumor dose calculated was 29 +/- 23 cGy/mCi 90Y and the average whole body dose was 0.76 +/- 0.3 cGy/mCi 90Y, resulting in a mean tumor to whole body dose ratio of 38:1. Only grade I/II non-hematologic toxicity was observed. Hematologic toxicity was also not severe; i.e., five of the seven patients who received 30 or 50 mCi/m2 of 90Y-DOTA-biotin experienced only transient grade III (but no grade IV) hematologic toxicity. Although six of ten patients developed humoral immune responses to the streptavidin, these were delayed and transient and hence may not preclude retreatment. Six of seven patients who received 30 or 50mCi/m2 90Y achieved objective tumor regression, including three complete and one partial response. The estimate of tumor to whole body dose ratio (38:1) achieved with PRIT in these NHL patients is higher than has been achieved in other studies using conventional RIT. Toxicity was mild and tumor response encouraging. PRIT clearly deserves additional study in patients with NHL.     

Radioguided surgery of breast cancer: radiation protection survey

The aim of this study was to estimate the radioactive risk for surgical staff performing radioguided sentinel lymph node (SN) biopsy and to calculate the contamination level in the operating room for assessment of the possible need for specific radiation protection procedures. We studied 20 patients who were selected for quadrantectomy and SN biopsy. The day before surgery a volume of 0.15 mL of 99mTc-nanocoll was injected: the activity was 3.11 +/- 0.85 MBq in group A (15 pts) and 11.6 +/- 0.6 MBq in group B (5 pts). External radiation to staff was evaluated by measuring the exposure rate in air one hour after radiopharmaceutical administration. The air KERMA rate during surgery was estimated considering the physical decay of 99mTc. Contamination of disposable materials and surgical instruments in the operating room was measured using a contamination monitor, whereas the residual activity in the SN and the injection site was measured with a gamma probe. The exposure rate at 20 cm from the injection site was 0.75 microSv/h when the most radioactive patients (group B) were treated. Contamination in the operating room proved to be negligible. Considering the number of radioguided treatments carried out by a surgeon in one year, an equivalent effective dose of 0.075 mSv was estimated; the recommended dose limit according to the relevant Italian law, DL 230/95, is 1 mSv/yr. Surgical staff therefore do not require a classification of "exposed workers" and there is no need to supply the operating room with special containers for radioactive waste.     

Agnogenic myeloid metaplasia with pleural extramedullary leukemic transformation

Agnogenic myeloid metaplasia (AMM) is one of the myeloproliferative disorders, and is usually accompanied by extramedullary hematopoiesis (EMH) in various organs, mainly in the liver, spleen and lymph nodes. Extramedullary hematopoiesis and/or leukemic transformation of EMH in the pleura is a rare occurrence and is usually asymptomatic. Pleural involvement is usually diagnosed on postmortem examination. Herein we describe a 71-year-old man with newly diagnosed agnogenic myeloid metaplasia who was evaluated for progressively worsening dyspnea, pulmonary hypertension and bilateral pleural effusions. EMH involving the lungs and pleura was suspected. A sulfur colloid technetium 99m bone marrow scan performed to detect extramedullary hematopoiesis was negative. The diagnostic thoracentesis yielded bloody fluid that contained a large population of myeloblasts, indicating pleural leukemic transformation. The patient received 100 cGy to the whole lung for treatment of pulmonary hypertension due to EMH. This was followed by 1500 cGy total dose of radiation to the left lung for pleural extramedullary leukemic transformation. Pleural effusions resolved and repeat echocardiography showed reduction of the pulmonary artery pressure. Three months later he had leukemic transformation involving the skin and lymph nodes. Four months after radiation therapy, he had full-blown acute myeloid leukemia. He received 2 cycles of Gemtuzumab ozogamicin (Mylotarg), allopurinol and hydroxyurea. Three months after initiation of chemotherapy, he deteriorated and received salvage chemotherapy of prednisone, VP-16 and imatinib mesylate (Gleevec). He was hospitalized for neutropenic fever and was diagnosed to have pulmonary aspergillosis. He died of multisystem failure 8 1/2 months after being diagnosed with AMM.