Radiation Precautions Research Articles

Evaluation of Patient Transmission Factor Following the Administration of 177Lu-DOTATATE.

177Lu-DOTATATE is a radionuclide therapy that is FDA approved for the treatment of somatostatin receptor-positive gastroenteropancreatic neuroendocrine tumors. Treatment facilities are required to determine the maximum radiation dose from such subjects to the maximally exposed member of the public, ensuring that the total effective dose equivalent (TEDE) does not exceed regulatory limits. If the calculated TEDE meets the regulatory limits, the patient is eligible for release and provided instructions with radiation precautions. This study aims to determine a mean transmission factor to the patient to improve accuracy and individualize the estimation of the TEDE.

Clinical Issues—April 2021

Scrubbed team members leaving the OR while x-rays are taken Key words: radiation source exposure, x-ray, distance and shielding, radiation protection devices, inverse square law. Cleaning radiation protection garments and devices Key words: radiation protection, cleaning reusable garments, eyewear, lead aprons, shielding devices. Implementing radiation precautions for pregnant health care workers Key words: scatter radiation, shielding, dosimeter, pregnant health care worker, protective garment. Protecting patients from radiation exposure Key words: scatter radiation, radiation protection devices, radiation shielding, radiation protection drapes, patient exposure. Wearing x-ray aprons that fit correctly Key words: body size, radiation protection garment sizing, x-ray, lead aprons, anthropomorphic phantom.

Commissioning process for high dose rate prostate brachytherapy

The aim of this study was to outline and examine the commissioning process of a treatment planning system (TPS) dedicated to high dose rate brachytherapy (HDR BT) prostate treatment and the associated equipment. HDR BT treatment facilitates dose escalation to the prostate and involved seminal vesicles in conjunction with external beam treatment while minimising the dose to the rectum, bladder and urethra. In comparison to low dose rate (LDR) BT, there is an increase in precision and control in source positioning and corresponding dose distribution which results in a high tumour control and low toxicity rates. Other advantages include no patient-specific radiation precautions, as patients are not radioactive following treatment, and decreased radiation exposure to clinical staff and the general public. Commissioning and implementation of a quality assurance program of HDR delivery system guarantees optimal treatment of patients. All aspects must be thoroughly tested prior to the delivery of the treatment to patients to ensure the safe delivery of the intended dose. Based on published guidelines developed by the American Association of Physicists in Medicine (AAPM) and the European Society for Radiotherapy and Oncology (ESTRO) all aspects of the treatment planning system software including the image acquisition, dose calculations and data transfer underwent the required acceptance and commissioning testing. The quality assurance testing of the equipment and the imaging system to be used was also carried out. This study provides a framework of the steps required for the commissioning of a HDR interstitial brachytherapy prostate treatment.

Selected Radiation Safety Aspects Including Transportation and Lodging After Outpatient 131I Therapy for Differentiated Thyroid Cancer.

Whether radioactive iodine (131I) treatments for differentiated thyroid cancer should be performed as an outpatient or inpatient remains controversial. The objective of this study was to survey selected aspects of radiation safety of patients treated with 131I for differentiated thyroid cancer as an outpatient. An e-mail invitation was sent to over 15,000 members of ThyCa: Thyroid Cancer Survivors' Association, Inc. to complete a web-based survey on selected aspects of radiation safety regarding their last outpatient 131I treatment. A total of 1549 patients completed the survey. Forty-five percent (699/1541) of the respondents reported no discussion on the choice of an inpatient or outpatient treatment. Moreover, 5% (79/1541) of the respondents reported that their insurance company made the decision. Survey respondents recalled receiving oral and written radiation safety instructions 97% (1459/1504) and 93% (1351/1447) of the time, respectively. Nuclear medicine physicians delivered oral and written instructions to 54% (807/1504) and 41% (602/1462) of the respondents, respectively. Eighty-eight percent (1208/1370) of the respondents were discharged within 1 hour after receiving their 131I treatment, and 97% (1334/1373) traveled in their own car after being released from the treating facility. Immediately post-therapy, 94% (1398/1488) of the respondents stayed at their own home or a relative's home, while 5% (76/1488) resided in a public lodging. The specific recommendations received by patients about radiation precautions varied widely among the respondents. Ninety-nine percent (1451/1467) of the respondents believed they were compliant with the instructions. This is the largest, patient-based survey published regarding selected radiation safety aspects of outpatient 131I treatment. This survey suggests several concerns about radiation safety, such as the decision process regarding inpatient versus outpatient treatment, instructions about radiation safety, transportation, and lodging after radioiodine therapy. These concerns warrant further discussion, guidelines, and/or policies.

Radiation safety of receptive anal intercourse with prostate cancer patients treated with low-dose-rate brachytherapy

PurposeProstate low-dose-rate (LDR) brachytherapy involves implantation of radioactive seeds permanently into the prostate gland. During receptive anal intercourse, the penis of the partner may come in close proximity to the implanted prostate gland. We estimate the potential intrarectal dose rates and suggest guidance on radiation precautions. Methods and MaterialsOne hundred two patients were included in the study. After implantation, with patients under anesthesia in the dorsal lithotomy position, a new set of ultrasound (US) images and a CT scan were obtained. The images were fused, radioactive seeds and US probe locations were determined on the CT, and prostate, bladder, and rectal contours were drawn on the US. Dose rates (cGy/h) were calculated for the portion of the US probe spanning the prostate for several dose-volume histogram parameters. ResultsTwenty patients were treated with 125I and 82 patients with 103Pd. Average dose rates at Day 0 to the portion of the US probe spanning the prostate were 2.1 ± 1.3 cGy/h and 2.5 ± 0.8 cGy/h for patients treated with 125I and 103Pd, respectively. After 60 days, average calculated probe dose drops to 1.0 ± 0.6 cGy/h and 0.2 ± 0.1 cGy/h for 125I and 103Pd, respectively. ConclusionsDuring the immediate weeks after prostate seed implant, the estimated intrarectal dose rates are higher in 103Pd compared to 125I. As 103Pd decays faster than 125I, 2 months after the implant, radiation exposure from 103Pd becomes lower than 125I. Receptive anal intercourse time should be kept as low as possible during 2 and 6 months after low-dose-rate brachytherapy of the prostate with 103Pd and 125I, respectively.

Radiation Safety of Receptive Anal Intercourse with Prostate Cancer Patients Treated with Low-Dose-Rate Brachytherapy

Prostate low-dose-rate (LDR) brachytherapy involves implantation of radioactive seeds permanently into the prostate gland. The International Commission on Radiological Protection (ICRP) provides guidance on radiation precautions based on potential external exposures to members of the public and/or carers for prostate seed brachytherapy. During receptive anal intercourse (RAI) the penis of the partner may come in close proximity to the implanted prostate gland. Here, we estimate the potential intra-rectal dose rates in prostate cancer patients treated with LDR brachytherapy. One hundred and two patients were included in the study. At the end of the seed implantation procedure, while the patients under anesthesia in the dorsal lithotomy position a new set of ultrasound (US) images and a CT scan were obtained. The images were fused, radioactive seeds and US probe locations were determined on the CT, and prostate, bladder and rectal contours were drawn on the US for dosimetry. Dose rates (cGy/h) were calculated for the portion of the US probe spanning the prostate for several DVH parameters. Twenty patients were treated with Iodine-125, and 82 patients with Palladium-103. At day 0, maximal and average dose rates per hour to the US probe for patients treated with 125I were 6.7±4.8cGy/hr and 2.1±1.3cGy/hr, and for 103Pd were 10.3±4.0cGy/hr and 2.5±0.8cGy/hr, respectively. After 60 days, average calculated probe dose dropped to 1.0 ±0.6cGy/hr and 0.2 ±0.1cGy/hr, for 125I and 103Pd, respectively. During the immediate weeks after prostate seed implant, the estimated intra-rectal dose rates are higher in 103Pd compared to 125I. Both would likely exceed equivalent ICRP guidance, after limited RAI time. As 103Pd decays faster than 125I, two months after the implant, radiation exposure from 103Pd becomes lower than 125I. RAI should be avoided for 2 and 6 months after LDR brachytherapy of the prostate with 103Pd and 125I, respectively.

An investigation into the activity levels of I-131 radioiodine patients 7 days post radioiodine treatment and the subsequent effects on their radiation precautions

of these materials should properly be taken in to account. Methods: In this work, an extended CT data have been used to appropriately account for the presence of a high density material in a patient. Unlike the conventional un-extended CT data, the extended CT data provide a maximum Hounsfield Unit (HU) value of ~30,000. Therefore, in principle it is possible to get varying HU values for a range of high density materials commonly found in patients. Though the extended CT data provide distinguishable HU values for different high density materials, it is practically very challenging to establish a robust Relative Electron Density (RED)– HU calibration table for a range of materials. However, for a commonly found prosthetic materials such as Titanium (Ti), Stainless Steel (SS) and Co–Cr– Mo alloy with known densities, an extended RED–HU calibration table can be established for the purpose of treatment planning. Results: Our preliminary results with extended CT data have been very encouraging. Further tests are required to establish this technique for clinical use. Results from these studies will be presented.

Thyroid cancer: radiation safety precautions in 131I therapy based on actual biokinetic measurements.

To formulate radiation precautions for patients with thyroid cancer who are undergoing thyroid hormone withdrawal-induced hypothyroidism and iodine 131 ((131)I) therapy through actual biokinetic measurements. Informed consent and institutional review board approval were obtained. From October 2008 to December 2011, consecutive patients with differentiated thyroid cancer who had been prepared for (131)I ablation treatment or (131)I treatment for metastatic disease during follow-up were prospectively recruited. Calculations based on deduced whole-body retention and measured iodine biokinetics in thyroidal tissue were derived to determine the thyroidal and extrathyroidal compartment uptake fractions and effective half-lives. Precaution times necessary to avoid close contact with family members and the general public were derived from these parameters and regulatory dose limits. Seventy-seven patients (36 with ablation treatments, 41 with follow-up treatments) were eligible for the analysis. Actual dose rates from patients after therapeutic (131)I administration were greatly lower than those described in the American Thyroid Association (ATA) and Nuclear Regulatory Commission (NRC) models: The mean initial dose rate at 0.3 m for patients with ablation treatment was only 28% (0.183/0.655 µSv/h/MBq) ± 2.9 (standard deviation) (range, 12.1%-38.3%) and 36% (0.183/0.511 µSv/h/MBq) ± 3.7 (range, 15.5%-49.1%) of that described in the NRC and ATA models, respectively; the equivalent values for patients with follow-up treatment were only 30% (0.195/0.655 µSv/h/MBq) ± 3.5 (range, 12.5%-45.3%) and 38% (0.195/0.511 µSv/h/MBq) ± 4.5 (range, 16.0%-58.1%), respectively. The actual mean effective (131)I half-life in the thyroid remnant tissue was greatly lower than that described in the ATA and NRC models: 47.6 versus 175.2 hours. On the basis of the current dose limits, typically administered activities of 3.7 GBq to a patient with ablation treatment or 7.4 GBq to a patient with follow-up treatment required 3 days of sleeping apart for keeping the doses to pregnant women and children below 1 mSv. No precautions were required for non-cosleeping nonpregnant adult family members.

Radiation exposure of eyes, thyroid gland and hands in orthopaedic staff: a systematic review.

BackgroundVarious procedures, especially minimal invasive techniques using fluoroscopy, pose a risk of radiation exposure to orthopaedic staff. Anatomical sites such as the eyes, thyroid glands and hands are more vulnerable to radiation considering the limited use of personal protective devices in the workplace. The objective of the study is to assess the annual mean cumulative and per procedure radiation dose received at anatomical locations like eyes, thyroid glands and hands in orthopaedic staff using systematic review.MethodsThe review of literature was conducted using systematic search of the database sources like PUBMED and EMBASE using appropriate keywords. The eligibility criteria and the data extraction of literature were based on study design (cohort or cross-sectional study), study population (orthopaedic surgeons or their assistants), exposure (doses of workplace radiation exposure at hands/fingers, eye/forehead, neck/thyroid), language (German and English). The literature search was conducted using a PRISMA checklist and flow chart.ResultsForty-two articles were found eligible and included for the review. The results show that radiation doses for the anatomical locations of eye, thyroid gland and hands were lower than the dose levels recommended. But there is a considerable variation of radiation dose received at all three anatomical locations mainly due to different situations including procedures (open and minimally invasive), work experience (junior and senior surgeons),distance from the primary and secondary radiation, and use of personal protective equipments (PPEs). The surgeons receive higher radiation dose during minimally invasive procedures compared to open procedures. Junior surgeons are at higher risk of radiation exposure compared to seniors. PPEs play a significant role in reduction of radiation dose.ConclusionsAlthough the current radiation precautions appear to be adequate based on the low dose radiation, more in-depth studies are required on the variations of radiation dose in orthopaedic staff, at different anatomical locations and situations.

Radioimmunotherapy for B-Cell Non-Hodgkin Lymphomas

Radioimmunotherapy (RIT) is a safe and effective therapeutic option for patients with indolent B-cell non-Hodgkin lymphomas (NHL), in both up-front and relapsed/refractory settings. Two approved agents (90Y-ibritumomab tiuxetan and 131I-tositumomab) are available in the United States. Both target CD20 with similar clinical outcomes but with unique clinical considerations and radiation precautions due to the use of varying radioisotopes. This paper reviews the available evidence for these approved RIT agents and examines the recently published and ongoing clinical trials of potential novel indications for aggressive B-cell NHL. A pretreatment biodistribution evaluation required before administering the 90Y-ibritumomab tiuxetan therapeutic dose has been removed, which once limited its usage. The potential clinical applications of RIT include relapsed/refractory indolent B-cell NHL, diffuse large B-cell lymphoma, indolent lymphoma in the front-line setting, and mantle cell lymphoma. Multiple novel RIT agents are in preclinical and clinical development, and the addition of radiosensitizers or external-beam radiotherapy may act in synergy with RIT for both indolent and aggressive lymphomas. The risk of treatment-related myelodysplastic syndrome does not appear to be higher in patients treated with RIT over those receiving chemotherapy alone. RIT is a safe, effective, and significantly underutilized therapy for patients with B-cell NHL, and many studies have demonstrated the efficacy of 90Y-ibritumomab tiuxetan and 131I-tositumomab for relapsed/refractory indolent B-cell lymphomas. Continued research to establish its efficacy for other lymphoma subtypes is warranted.

Bremsstrahlung parameters of praseodymium-142 in different human tissues: a dosimetric perspective for 142Pr radionuclide therapy

Praseodymium-142 [T 1/2=19.12h, [Formula: see text]=2.162MeV (96.3%), Eγ=1575keV (3.7%)] is one of the (141)Pr radioisotopes. Many studies have been attempted to assess the significance of usage (142)Pr in radionuclide therapy. In many studies, the dosimetric parameters of (142)Pr sources were calculated by modeling (142)Pr sources in the water phantom and scoring the energy deposited around it. However, the medical dosimetry calculations in water phantom consider Bremsstrahlung production, raising the question: "How important is to simulate human tissues instead of using water phantom?" This study answers these questions by estimation of (142)Pr Bremsstrahlung parameters. The Bremsstrahlung parameters of (142)Pr as therapeutic beta nuclides in different human tissues (adipose, blood, brain, breast, cell nucleus, eye lens, gastrointestinal tract, heart, kidney, liver, lung deflated, lymph, muscle, ovary, pancreas, cartilage, red marrow, spongiosa, yellow marrow, skin, spleen, testis, thyroid and different skeleton bones) were calculated by extending the national council for radiation protection model. The specific Bremsstrahlung constant (Γ Br), probability of energy loss by beta during Bremsstrahlung emission (P Br) and Bremsstrahlung activity (A release)Br were estimated. It should be mentioned that Monte Carlo simulation was used for estimation of (142)Pr Bremsstrahlung activity based on the element compositions of different human tissues and the calculated exposures from the anthropomorphic phantoms. Γ Br for yellow marrow was smallest amount (1.1962×10(-3) C/kg-cm(2)/MBq-h) compared to the other tissues and highest for cortical bone (2.4764×10(-3) C/kg-cm(2)/MBq-h), and, overall, Γ Br for skeletal tissues were greater than other tissues. In addition, Γ Br breast was 1.8261×10(-3) C/kg-cm(2)/MBq-h which was greater than sacrum and spongiosa bones. Moreover, according to (A release)Br of (142)Pr, the patients receiving (142)Pr do not have to be hospitalized for radiation precautions and the Bremsstrahlung production does not prevent the therapy for outpatients. However, modeling (142)Pr source in water phantom for simulation of (142)Pr source in soft tissues could be acceptable due to similarity of Γ Br in water and soft tissues; this approximation is a gross computation in the mediums encompassing high atomic numbers. These data may be practical in the investigation of Bremsstrahlung absorbed dose where (142)Pr is involved in radionuclide therapy.

Beta induced Bremsstrahlung exposure in DNA and RNA

The Bremsstrahlung exposure induced by some of the therapeutic beta nuclides ( 90Y, 143Pm, 169Er, 204Tl, 210Bi, 89Sr, 45Ca and 131I) in DNA and RNA has been calculated by extending the national council for radiation protection model. It has estimated the specific Bremsstrahlung constant (Γ Br), Probability of energy loss by beta during Bremsstrahlung emission ( P Br ) and Bremsstrahlung activity ( A release ) Br . The estimated Bremsstrahlung activities of pure beta nuclides in DNA and RNA are extremely large (10 2 GBq–10 6 GBq). The patients receiving such nuclides would never receive that much activity because of prohibitive radiation toxicity (few 100 MBq). Thus the patients receiving these pure beta emitting nuclides do not have to be hospitalized for radiation precautions. It is also estimated the Bremsstrahlung yield ( I Br ) for wide energy range (0.01 MeV–100 MeV) using the tabulated values given for elements by Lucien pages. The variation of I Br as a function of incident electron energy is shown graphically. This data may be useful in the analysis of Bremsstrahlung dose where beta emitting nuclide is involved in medical therapy.

Bremsstrahlung exposure of tissues from beta-therapeutic nuclides

The Bremsstrahlung exposure rate from beta point source, probability of energy loss by beta during the Bremsstrahlung emission and the Bremsstrahlung activity of tissues have been calculated. The Bremsstrahlung yield for tissues in the wide energy range is also estimated from 0.01 to 100MeV using the tabulated values given for elements by Lucien pages. The estimated Bremsstrahlung activities of pure beta nuclides in all types of tissues are extremely large (102–106GBq). The patients receiving such nuclides would never receive that much activity because of prohibitive radiation toxicity (few 100MBq). Thus the patients receiving these pure beta emitting nuclides do not have to be hospitalized for radiation precautions.

Validation of Flow Cytometric Measurements of NK Cytotoxicity Against Chromium Release Assay for Use in Clinical Monitoring of Immune Function.

Chromium (51Cr) release assays have long been a standard technique for measuring the cytolytic activity of various immune effector cells. Although relatively easy to perform, these assays suffer from problems with sensitivity and require special radiation precautions limiting their routine use in clinical laboratories. Several flow cytometric techniques measuring cytotoxicity have been introduced and used as a measure of immune response. These assays are more rapid than the 51Cr based assay and have the added advantage of freeing the laboratory from the precautions required when working with radioactivity. Such testing has however largely been restricted to the research setting. In an attempt to extend these benefits to a clinical laboratory, we attempted to validate two commercially available flow cytometry kits (CyToxiLux Plus® & GranToxiLux®, OncoImmunin, Gathersburg, MD) measuring either caspase or granzyme B activity inside K562 target cells induced by interaction with NK cells. These assays were then compared with a standard NK cytotoxicity assay using 51Cr release technique. With K562 as a target, we parallel tested three CD56+CD3-KIR- NK clones; both the 51Cr and caspase based cytotoxicity values were highly positive. With WH autologous EBV cell line as target, we parallel tested five NK clones and five normal control donors as effectors. As expected, all cytotoxicity values for both assays were <10%. The caspase and granzyme assays were then compared and the degree of separation in the flow cytometric plots of the granzyme based assay were found to be marginally superior facilitating analysis of the data. The granzyme B assay therefore was chosen for investigation in the clinical samples. The granzyme and 51Cr assays were then compared both in 49 normal control donors and in 10 patients. There was a high level of concordance between the two assays. Comparing all results using linear correlation yielded a squared correlation (R2) value of 0.6878. However, given the wide range of NK activity in normal control donors the degree of positivity may not be clinically significant. Therefore, the data was examined in the context of a positive 51Cr response. Using a 2×2 table to exam the level of agreement, the kappa statistic was 0.63, indicating good agreement between the assays. When progressively fewer effector cells were added to a fixed number of target cells, the % cytotoxicity decreased from 39% to 0% with the flow cytometric assay and from 26% to 1% with the 51Cr assay. In the normal control donors the positive values ranged from 17% to 65% cytotoxicity using the flow assay compared with the previous range of 15% to 72% established with 51Cr. Patients having cytotoxicity values below 17% were deemed as having an unreactive or abnormal low result. One of the patients with few CD56+CD3- NK cells had consistently low cytotoxicity each time tested. For the patients who have either undergone allogeneic stem cell transplantation or have a known immunodeficiency, further clinical follow-up will serve to establish the clinical relevance of these measurements. These preliminary data suggest that the flow cytometric technique can be used in the clinical setting for immune monitoring.

External dose rates in radioiodine treatment of benign goitre: Estimation versus direct measurement

Objective. According to European recommendations, the external dose rate (ED) in radioiodine‐treated goitre patients can be determined by estimating from calculation of the residual activity (RA) in the patient based on radioiodine uptake measurements or by measuring ED directly. In the European guidelines, “Radiation Protection 97”, it is assumed that an RA of 600 MBq 131I causes an ED of 30 μSv/h at a distance of 1 m. This implies a slope of 0.05 µSv/h/MBq for the ratio ED/RA relationship, but, theoretically, this ratio is higher, at 0.07, a difference that is due to measurement in air versus in a scattering medium. We sought to investigate what the true ratio might be. Material and methods. Sixty‐six patients scheduled for radioiodine treatment of benign goitre (mean size 102 mL, range 20–440), who received 131I orally (mean 984 MBq, range 173–3700) were examined. After 24 h and 96 h iodine uptake percentage we examined 7269 patients scheduled for radioiodine treatment of benign goitre (mean size 1042 mL, range 20–440) who received 131I orally (mean 101,100 MBq, range 180–3700). After 24 h and 96 h, the iodine uptake was determined, RA calculated and ED measured using a hand‐held dosimeter. Results. At 24 and 96 h, we observed a slope ratio of 0.103 µSv/h/MBq (95 % CI: 0.09564–0.111) and 0.101 µSv/h/MBq (95 % CI: 0.0915–0.11107), respectively, for the ED/RA relationship. None of the confidence intervals included the value 0.05 µSv/h/MBq, reflecting that the observed slopes differed significantly from the expected slope (p<0.001). Consequently, an RA of 600 MBq typically causes an ED of 60 and not 30 μSv/h, and therefore dose rates based on radioiodine uptake measurements and established assumptions were only about half as high as the directly measured values. We noticed that with an RA roughly below 450 MBq, the anticipated slope of 0.05 µSv/h/MBq is within the prediction interval of our claimed ratio, therefore we cannot rebut the anticipated slope for lower doses. Conclusions. Dose‐rate estimates based on radioiodine uptake measurements and established assumptions were only about half as high as the directly measured values in patients receiving doses higher than the widely accepted limits for outpatient treatment. This finding may have substantial implications for us, in that it makes a considerable difference whether the radiation precautions are taken to limit doses to the patient's surroundings and for deciding if a patient may or may not be regarded as an outpatient, as well as for the safe discharge of an inpatient from hospital.

Use of Low-Energy X-Rays in the Treatment of Superficial Nonmelanomatous Skin Cancers

The Photon Radiosurgery System (PRS), developed by the Photoelectron Corporation in Lexington, Massachusetts, produces low-energy x-rays from the tip of a needle-like probe at a high dose-rate. This portable device can be located directly over the target volume, delivering a uniform dose while sparing surrounding normal structures. To evaluate its radiotherapeutic profile, a prospective phase I Food and Drug Administration trial was performed utilizing this device in the management of nonmelanomatous skin cancers. Target doses ranged from 10 Gray in one fraction to 30 Gray in three weekly fractions. Thirty-eight lesions in 18 patients were treated. The overall completed response rate for all histologies at 12 months was 83%. No significant acute or late morbidity was encountered. Our results to date demonstrate that low-energy x-rays produced by the PRS were as effective in managing nonmelanomatous skin tumors as other radiation treatment modalities without the need for cumbersome shielding or radiation precautions.

Allergic reaction to nanocolloid during lymphoscintigraphy for sentinel lymph node biopsy

Editor—We read with interest the case report by Stefanutto and colleagues,1Stefanutto TB Shapiro WA Wright PMC Anaphylactactic reaction to isosulphan blue.Br J Anaesth. 2002; 89: 527-528Crossref PubMed Scopus (23) Google Scholar concerning an anaphylactic reaction to isosulphan blue dye during routine sentinel lymph node biopsy for breast surgery. We agree that anaesthetists must be aware of the potential serious risks of anaphylaxis in this group of patients. However, this is not a new finding; anaphylaxis to the blue dye has been well documented.2Cashman JN Editorial—Sentinel lymph node biopsy: anaesthetic implications.Eur J Anaesthesiol. 2001; 18: 273-276Crossref PubMed Google Scholar We would like to add a further potential area of concern that was highlighted recently in a patient, of what appears to be an allergic reaction to technetium99m nanocolloid during lymphoscintigraphy. The patient, a 31-yr-old male weighing 75 kg, was admitted to hospital after previous removal of a malignant melanoma (Breslow thickness 1 mm) from over his left scapula, for further wide local excision, lymphoscintigraphy, and sentinel node biopsy. He was taking no medications, and was without any significant medical history. There was no past history of asthma or any atopic episodes. On the day before surgery, he underwent an intradermal injection of technetium99m nanocolloid albumen. Within 10 min of injection of the colloid, the patient developed a widespread, non-itchy urticarial skin reaction. There was no associated wheeze, difficulty breathing, or cardiovascular symptoms. Immediately, he was given chlorpheniramine 10 mg i.v., and the rash settled without further consequence over the next hour. The subsequent general anaesthetic was carried out uneventfully. Induction of anaesthesia was facilitated with fentanyl 0.5 mg kg−1 and propofol 2.5 mg kg−1. Anaesthesia was maintained using isoflurane in oxygen and nitrous oxide with the patient breathing spontaneously. Chlorpheniramine 10 mg and hydrocortisone 100 mg were given intravenously at induction. During surgery, patent V blue dye 0.5 ml was injected intradermally without incident. Another general anaesthetic 5 weeks later for block dissection of axillary nodes was equally uneventful. The use of sentinel lymph node biopsy in the staging of malignancies, particularly melanomas and breast cancers, has gained in popularity in recent years. The accuracy of injecting blue dye around the site of the primary malignancy can be increased using lymphoscintigraphy and intraoperative gamma probe detection after radiocolloid injection. The most commonly used radiopharmaceutical agent is technetium99m nanocolloid, which requires standard radiation precautions to be taken when handling to protect personnel. We are unable to find any reports of anaphylactoid type reactions to the radiocolloid in the literature. It could be argued that there is no evidence that the patient in this case had a true anaphylactic reaction. Further skin-prick testing was not carried out as the intradermal injection is a form of skin testing in itself. However, according to a classification based on symptom severity,3Mertes PM Laxenaire M-C Allergic reactions occurring during anaesthesia.Eur J Anaesthesiol. 2002; 19: 240-262Crossref PubMed Google Scholar our patient reacted with Grade 1 type cutaneous symptoms that can consist of generalized erythema, urticaria or angio-oedema. A similar reaction with a widespread blue rash occurred after injection of blue patent V dye during sentinel lymph node biopsy for breast carcinoma.4Mullan MH Kissin MW Deacock SJ Minerva.Br Med J. 2000; 321: 460Crossref Google Scholar This was treated successfully with hydrocortisone and chlorpheniramine. We suggest that it is possible that there may be some cross reactivity with blue dye and it is worth noting even though the patient did not suffer any serious consequences. Patients who have urticarial reactions at lymphoscintigraphy may have an increased risk of anaphylaxis intraoperatively, which anaesthetists must be aware of and give prophylactic treatment. We would also like to point out that, in our establishment, all such patients are treated as inpatients and not as day cases. We would agree with the authors that the day surgery setting may not be a suitable clinical area for such cases.

A generalized algorithm for determining the time of release and the duration of post-release radiation precautions following radionuclide therapy.

The Nuclear Regulatory Commission has recently amended its regulation concerning patients who have received therapeutic amounts of radioactivity. The amended regulation allows patient release based on a total effective dose equivalent (TEDE) limit of 5 mSv (500 mrem) instead of the activity administered or retained [1,110 MBq (30 mCi)] or the dose rate [0.05 mSv h(-1) (5 mrem h(-1)) at 1 m]. Record-keeping and written post-release radiation safety precautions are required, however. A general algorithm, combining patient-specific kinetics and dose rate measurements, has been developed to systematically determine the actual duration of post-release radiation precautions as well as the time of release post-treatment. This algorithm is based on the maximum permissible effective dose equivalents (MPEDEs) of the respective cohorts exposed, 5 mSv (500 mrem) to non-pregnant adult family members and 1 mSv (100 mrem) to pregnant women, children, and members of the general public. Operational equations to determine the times post-radionuclide treatment of release from medical confinement, of not working, of avoiding pregnant women and children, of limiting holding of children, and of sleeping partners not sleeping together have been derived and illustrated with a hypothetical example. TEDE-based release criteria should be less restrictive than the previous activity-based or dose rate-based release criteria. However, post-release radiation precautions may be more intrusive and longer in duration than those to which most practitioners have grown accustomed. Up to now, however, the duration (typically 1-2 d) of advised post-release precautions had not been rigorously derived from MPEDEs and were generally inappropriately short. Even so, dose-based release criteria should prove more cost-effective overall than hospitalization of patients commonly imposed by activity-based and dose rate-based release criteria.

A nine-year evaluation of emergency department personnel exposure to ionizing radiation

Emergency department personnel experience potential occupational hazards from exposure to ionizing radiation (x-rays). To assess this risk, ionizing radiation exposure was analyzed during a nine-year period for 128 ED personnel. The group consisted of 21 physicians, 92 nurses, and 15 ancillary personnel. Exposure was measured for both penetrating and nonpenetrating radiation using standard film dosimeter badges. Film badge use compliance was 66.7% for physicians, 86.2% for nurses, and 86.7% for ancillary personnel. Penetrating radiation exposure averaged 0.12 mrem/month for physicians, 0.70 mrem/month for nurses, and 0 mrem/month for ancillary personnel, all less than the average natural background exposure. We concluded that if standard radiation precautions are taken, the occupational risk from ionizing radiation exposure to personnel in the ED is minimal, and that routine monitoring of radiation exposure of ED personnel is unnecessary.

Cerebral blood flow and metabolism studies comparing krypton 85 desaturation technique with argon desaturation technique using the mass spectrometer.

Average cerebral blood flow determinations were performed 26 times comparing argon desaturation curves measured by mass spectrometry to the krypton 85 desaturation technique of McHenry. 1 During 17 of these studies krypton 85 and argon desaturations were performed simultaneously. Mean cerebral blood flow difference was 7.2 ± 5.7% for simultaneous determinations and 7.9 ± 6.6% for the total, establishing that the two techniques are comparable. Some of the advantages of using argon in mass spectrometry include: no blood needs to be withdrawn, curves can be observed at the time they are obtained, radiation precautions are not required, multiple studies do not affect the patient, and partial pressures of oxygen and carbon dioxide can be observed constantly.