Patient Effective Dose Research Articles

Fluoro-D-glucose (18F-FDG) PET/CT and patient effective dose

In the present study, patient exposures Evaluations herein concern patient exposures (positron and gamma-rays) that result from fluoro-D-g1ucose PET and CT were investigated and radio-carcinogenic risks estimated. The six-month study, conducted at King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia, included a total of 636 patients (lymphoma = 187, nasopharyngeal carcinoma = 82, thyroid = 30 and others = 337). Patient effective dose estimations were made from administered radioactivity (AA) and CT exposures (General Electric (GE) PET/CT VCT), the mean and range of AA (in MBq) and effective dose (in mSv) were respectively: lymphoma 433.9 ± 70.6 (297.5–735.9) and 8.2 ± 1.3 (5.7–13.9); nasopharyngeal carcinoma 417.7 ± 55.9 (325.6–547.6) and 7.9 ± 1.1 (6.2–10.4); thyroid 450.1 ± 71.4 (344.1–566.1) and 8.6 ± 1.4 (6.5–10.8). In the same units, the mean and range of AA and effective dose for other procedures were 421.6 ± 58.3 (283.4–606.8) and 8.0 ± 1.1 (5.4–11.5), respectively. The mean and range of the tube current-time product (mAs) for the CT procedures were 30 (8.2–42.4). A constant tube voltage of 120 kVp was used for all patient procedures. On average, CT contributed 73% to patient effective doses, suggesting that optimisation of CT acquisition parameters are vital in seeking effective dose reduction. Patient effective doses were found to be a little above that of previous studies.

Dosis de radiación durante la inserción guiada por fluoroscopia de un dispositivo de acceso venoso central: un estudio observacional retrospectivo

IntroductionCentral venous access devices (CVAD) are used to deliver intravenous therapy to the bloodstream. CVAD insertion is sometimes fluoroscopically guided and thus associated with radiation dose to both the patient and the staff members within the room. The objective of this study is to assess the radiation dose to the patient through a retrospective audit and directly measure the exposure to staff members in simulated procedures. A secondary objective is to evaluate the radiation exposure to the staff and patients when utilising fluoroscopic pulse rate of 7.5 pps and 4 pps. Material and MethodsA retrospective audit of patients undergoing Permcath and Hickman line insertions was conducted. The patients were grouped by the pulse rate used for the duration of the study; 4 pulses per second (pps) (n=24) and 7.5 pps (n=33). A STEP OD-2 monitor and PMMA was used in a simulated environment to estimate the radiation exposure to locations that a Radiologist, Nurse and Radiographer would be standing during the procedures using the average procedure details collected in the retrospective audit. Measurements were conducted at heights to reflect a whole body estimate and an estimate to the lens of the eye. ResultsThe results show that the median dose area product (DAP) for CVAD insertion is 0.7Gy.cm2 and 0.3Gy.cm2 for procedures done at 7.5 pps and 4 pps, respectively. This corresponded to an effective dose of 0.22 mSv and 0.1 mSv. The radiologist, nurse and radiographer were exposed to a whole-body shielded dose of 0.36μSv, 0.1μSv and 0.05μSv when 7.5 pps was utilised and 0.13μSv, 0.03μSv and 0.02μSv when 4 pps was used. The exposure to the head of radiologist, nurse and radiographer was 2.1μSv, 1.4μSv, and 0.6μSv in the 7.5 pps studies and 0.7μSv, 0.5μSv, and 0.2μSv when 4pps was used. ConclusionThe patient effective dose was estimated to be 0.1-0.22 mSv depending on the fluoroscopic pulse rate utilised during CVAD insertions. Additionally, The radiologist, nurse and radiographer whole body and lens exposure was estimated in a simulated setting. In all cases, there was a statistically significant dose reduction when the lower fluoroscopic pulse rate was used. Thus, where possible, consideration should be given to utilising a lower pulse rate during CVAD insertions to reduce the exposure to both staff and patients.

Radiation dosimetry of 18F-AzaFol: A first in-human use of a folate receptor PET tracer

BackgroundThe folate receptor alpha (FRα) is an interesting target for imaging and therapy of different cancers. We present the first in-human radiation dosimetry and radiation safety results acquired within a prospective, multicentric trial (NCT03242993) evaluating the 18F-AzaFol (3′-aza-2′-[18F]fluorofolic acid) as the first clinically assessed PET tracer targeting the FRα.Material and methodsSix eligible patients presented a histologically confirmed adenocarcinoma of the lung with measurable lesions (≥ 10 mm according to RECIST 1.1). TOF-PET images were acquired at 3, 11, 18, 30, 40, 50, and 60 min after the intravenous injection of 327 MBq (range 299–399 MBq) of 18F-AzaFol to establish dosimetry. Organ absorbed doses (AD), tumor AD, and patient effective doses (E) were assessed using the OLINDA/EXM v.2.0 software and compared with pre-clinical results.ResultsNo serious related adverse events were observed. The highest AD were in the liver, the kidneys, the urinary bladder, and the spleen (51.9, 45.8, 39.1, and 35.4 μGy/MBq, respectively). Estimated patient and gender-averaged E were 18.0 ± 2.6 and 19.7 ± 1.4 μSv/MBq, respectively. E in-human exceeded the value of 14.0 μSv/MBq extrapolated from pre-clinical data. Average tumor AD was 34.8 μGy/MBq (range 13.6–60.5 μGy/MBq).Conclusions18F-Azafol is a PET agent with favorable dosimetric properties and a reasonable radiation dose burden for patients which merits further evaluation to assess its performance.Trial registrationClinicalTrial.gov, NCT03242993, posted on August 8, 2017

Results of the clinical evaluation of the low-dose protocols of the digital linear tomography of the chest

High levels of tuberculosis morbidity in the Russian Federation lead to the extensive use of X-ray diagnostics for the tuberculosis screening and assessment of the effectiveness of treatment. Digital radiography and computed tomography are traditionally used for the diagnostics of tuberculosis. These methods are associated with significant drawbacks: low specificity for radiography, high costs per examination, significant patient doses, and limited availability for computed tomography. As an additional method for the assessment of the effectiveness of the tuberculosis treatment it is possible to use linear tomography performed on the digital X-ray units. The aim of the current study was to evaluate the possibility of utilization of the digital linear tomography for the control of the effectiveness of tuberculosis treatment in a dedicated antitubercular medical facility. The study was divided in two stages. The first stage was aimed at the assessment of the diagnostic image quality of the digital linear tomograms obtained using the previously developed low-dose imaging protocols. Image quality assessment was performed using an anthropomorphic chest phantom and dedicated imitators of the lung lesions. Image quality was assessed by the experts (radiologists) based on the developed image quality criteria. Results of the first stage of the study indicate that all low-dose protocols allow obtaining images with at least acceptable image quality. Hence it was possible to propose low-dose protocols for clinical evaluations. The second stage of the study was performed as a prospective cohort survey aimed at the evaluation of the structure of X-ray examinations, patient doses and clinical image quality of the digital linear tomograms in antitubercular early treatment center. The cohort survey included two patient samples, uniform by age and gender composition, anthropometric characteristics and structure of diagnosis. One of the samples was imaged using standard (vendor) digital linear protocols, other – using the proposed low-dose protocols. Dose data collection (measurement of dose-area product and subsequent calculation of effective dose) and expert image quality assessment was performed for each patient. The results of the second stage of the study indicate that the use of the low-dose protocols allow reducing the patient effective doses per examination up to a factor of 6–8 (0.56 – 5.9 mSv for standard protocols; 0.2 – 1.15 mSv for low-dose protocols) due to the reduction in tube current-time product (126 mean mAs and 11 mean mAs, respectively). The dose reduction is accompanied by the reduction in the image quality of the linear tomograms (from “excellent” or “good” for standard protocols to “acceptable” for low-dose protocols). However, that dose not hinder the conclusion decision and identification of pathologies. Results of the study indicate that digital linear tomography can be used for the evaluation of the dynamics of the pathological process in the lungs with the previously defined localization of the pathology. The presented low-dose protocols were implemented into radiological practice of the antitubercular early treatment center. Currently, the proposed low-dose protocols are under evaluation for the large-scale study on the base of general practice hospitals

Sympathetic overdrive in patients with impaired carbohydrate metabolism

Clinical studies have shown that sympathetic hyperactivation (sympathetic overdrive) is one of the main features of arterial hypertension, type 2 diabetes, and obesity, which are often found simultaneously.The landmark British Prospective Diabetes Study (UKPDS), which lasted 20 years, showed that beta-blockers reduce any-cause mortality by 23 % in patients with young and middle-aged hypertension, overweight or obese with diabetes 2 type. The researchers concluded that the advantage of long-term use of BB in this study is due to the fact that in a population of patients with obesity, diabetes mellitus, hypertension and an extremely high level of activity of the sympathetic system of β1-blockade is especially effective.An analysis of subsequent large-scale clinical trials of the effectiveness of beta-blockers (in particular, bisoprolol in CIBIS II) showed that in patients with heart failure and diabetes, these drugs reduce overall mortality by 16 %.The safety study of the use of bisoprolol in effective therapeutic doses in patients with type 2 diabetes mellitus and hypertension did not reveal a statistically significant negative effect of this highly selective β1-blocker on carbohydrate and lipid metabolism.

Evaluation of Patient's Dose and Estimate of Cancer Risk in Electrophysiology Studies and Ablation in Cath Lab Center of Afshar Hospital, Yazd, Iran

Introduction: Today electrophysiology studies and ablation have been developed due to increasing arrhythmias disorder of heart. In these diagnostic – treatments methods, the use of fluoroscopy can be causes patient radiation dose, therefore evaluation of patient's absorbed dose is necessary to protection of the radiation. The aim of this study was to evaluate the absorbed dose in patients undergoing electrophysiology and cardiac ablation and to estimate their risk of cancer in Yazd Afshar Hospital. Methods: This study was a cross-sectional study. In this study, the mean absorbed dose of referral patients for electrophysiology studies and ablation had been measured in the cat. Lab of Afshar Hospital, Yazd. The dosimeter had been used in this research was KAP meter, the M4 DIAMENTOR made in Germany that was able to measure dose-area product and time of the fluoroscopy. The patient effective dose was calculated by the PCXMC software from dose-area product. Results: The mean dose-area in ablation and electrophysiology studies was respectively 153.34±105.32 and 5.62 14.88 Gy.cm2 and the radiation time range was recorded 3.32 to 68.65 minutes and 1.03 to 6.28 minutes, respectively. The mean effective dose of ablation and electrophysiology studies were respectively 16.38 and 1.65 mSv. The cancer risk per ten thousands of patients, who were under the ablation and electrophysiology examinations were estimated 13 and 1.3 people, respectively. Conclusion: Increasing of patient dose due to ablation in this study relation to the other studies can be due to long old of image intensifier device.

Evaluation of Radiation dosimetry of 99mTc-HYNIC-PSMA and imaging in prostate cancer

This study aims to evaluate the radiation dosimetry of a new technetium-99m‒labelled small-molecule inhibitor of prostate-specific membrane antigen (HYNIC-Glu-Urea-A, 99mTc-HYNIC-PSMA) and its feasibility as a tumor-imaging agent in prostate cancer (PCa) patients. A total of 15 PCa patients were enrolled in this study. For the dosimetry study, 5 PCa patients received whole-body planar scans at 0.5 h, 1 h, 2 h, 4 h and 8 h after 99mTc-HYNIC-PSMA injection. The Dosimetry Toolkit (GE, Milwaukee) was used to process the data and segment the organs in the SPECT/CT images, which were then projected onto planar images. The organ-specific absorbed doses, total-body absorbed doses and 99mTc-HYNIC-PSMA effective doses of patients were calculated using OLINDA/EXM 1.1 software. Whole-body SPECT/CT images were also acquired from additional 10 prostate patients to investigate the feasibility of 99mTc-HYNIC-PSMA for imaging tumors by calculating the ratio of tumor-to-background tracer uptake at 2 h after 740 MBq administration. The total-body absorbed dose was 1.54E-03 ± 2.43E-04 mGy/MBq, and the effective dose was 3.72E-03 ± 4.5E-04 mSv/MBq. Compared to published studies of other similar PSMA tracers and 99mTc-targeted conventional tracers, the absorbed doses of 99mTc-HYNIC-PSMA in all organs showed that it could be used safely in the human body. In addition, 99mTc-HYNIC-PSMA showed high tracer uptake (with a tumor-to-background ratio of 9.42 ± 2.62) in the malignant lesions of PCa patients, making it a promising radiopharmaceutical imaging method for site-specific management of PCa.

Patient organ and effective dose estimation in CT: comparison of four software applications

BackgroundRadiation dose in computed tomography (CT) has become a topic of high interest due to the increasing numbers of CT examinations performed worldwide. Hence, dose tracking and organ dose calculation software are increasingly used. We evaluated the organ dose variability associated with the use of different software applications or calculation methods.MethodsWe tested four commercial software applications on CT protocols actually in use in our hospital: CT-Expo, NCICT, NCICTX, and Virtual Dose. We compared dose coefficients, estimated organ doses and effective doses obtained by the four software applications by varying exposure parameters. Our results were also compared with estimates reported by the software authors.ResultsAll four software applications showed dependence on tube voltage and volume CT dose index, while only CT-Expo was also dependent on other exposure parameters, in particular scanner model and pitch caused a variability till 50%. We found a disagreement between our results and those reported by the software authors (up to 600%), mainly due to a different extent of examined body regions. The relative range of the comparison of the four software applications was within 35% for most organs inside the scan region, but increased over the 100% for organs partially irradiated and outside the scan region. For effective doses, this variability was less evident (ranging from 9 to 36%).ConclusionsThe two main sources of organ dose variability were the software application used and the scan region set. Dose estimate must be related to the process used for its calculation.

Определение лучевой нагрузки на пациентов при стоматологических рентгенологических исследованиях

Purpose: Improving the quality of radiation assessment of patients of the medical institution of the dental profile using the calculated values of effective doses.
 Material and methods: Using the RED-2018 and ORTO-2018 programs, the values of effective patient exposure doses for 29 medical organizations of the dental profile were calculated. The obtained values of the effective dose were compared with the values specified in the methodological recommendations MP 0100 / 1659-07-26 of February 16, 2007 “Filling of forms of federal state statistical observation 3-DOZ”.
 Results: The analysis showed that the doses obtained using the RED-2018 and ORTO-2018 computer programs, respectively, are 21 and 14 times lower than the doses indicated in the methodological recommendations MP 0100 / 1659-07-26. 
 Conclusion: It is shown that the developed computer programs can be applied by a dentist practicing physician who performs an x-ray examination in order to automatically and reliably determine the patient’s dose when performing x-ray-mathematical studies in accordance with the guidelines of MU 2.6.1.2944-11 “Monitoring effective doses of patients during x-ray examinations” also used in the preparation of radiation hygienic passports of organizations and statistical form 3-DOZ. The indication of the actually calculated values of the effective dose of the patient, rather than repeatedly overestimated averages, will reduce the level of radiophobia in society.

Patient Dose Estimation from Digital Radiography Repeat Rate

Purpose: This research aimed at estimating the patient effective dose from digital radiography repeat rateand evaluating the factors that contribute to the repetition of radiographic procedures in two referral hospitals in Sari, Iran. Materials and Methods: Entrance skin dose and effective dose per common radiography procedures in digital radiography were measured. 1724 X-ray exposures were investigated prospectively. The annual number of each radiography procedure was obtained from the archives of the digital radiography department. The patient cumulative dose was the calculation from annual exposures Repeat Rate (RR) and effective dose per digital radiography procedures. Results: The mean exposure RR per examination was 1.12% and the total percentage of a repeat of all examination was 8.9%. Annual cumulative dose (man-mSivert) resulted from radiographic RR was 449.2.The chest and lumbar spine radiography had the highest annual number and the highest radiation dose, respectively; therefore, these procedures transfer the largest annual dose from repeated radiographic images to the patients. The factors leading to the repetition included the radiographer error (69%), the X-ray tube and equipment error (10.4%), the patient related error (16.1%) and other cases (4.1%). The average effective dose for each examination was 0.36 mSv. Conclusion: Digital radiographic repeat rate increases a 1.1 % annual patient effective dose from the base level that receives from the current radiographic examination. Inconsistency of the center of the digital panel and the central axis of the X-ray beam and error in the selection of the upright or table digital panel are among the most important factors in the repetition of digital radiography.

Cumulative effective dose caused by diagnostic imaging and its associated risk for cancer development in trauma patients referred to the emergency department

Background: The current study aimed to determine the cumulative effective dose caused by diagnostic imaging and its associated risk for cancer development in trauma patients referred to an emergency department. Methods: This study was carried out retrospectively in an emergency department (Kashan, Iran) from April 2015 to October 2015. Then, the types of diagnostic radiologic studies performed on adult trauma patients in their first 24 h upon presentation were recorded. Finally, the cumulative effective dose of trauma patients and its associated risk for cancer development were obtained. Results: In total, the patients received 3323 radiologic examinations including 2169 radiographs and 1154 computed tomography (CT)-scans. The most common type of plain radiographic and CT-scan examinations included anterior posterior and posterior anterior chest as well as head, respectively. The mean cumulative effective dose received by trauma patients referred to the emergency department was 2.47 ± 4.29 mSv. Most of the effective dose was from CT-scan examinations (90.65% of total cumulative effective dose; 2181.91 mSv). The majority of patients (83.40%) received between 0.00 and 5.00 mSv cumulative effective dose. Moreover, the cancer risk per average cumulative effective dose received by trauma patients was 1.01 × 10−4. Conclusions: In current study, the mean cumulative effective dose per each trauma patient (2.47 mSv) was relatively less than that of the other evaluated studies. It was also found that although the number of CT-scans was relatively few compared to plain radiographs, most of the cumulative effective dose of patients resulted from CT-scans; hence, using unnecessary CT-scan examinations should be avoided.

The peptide analogue of neurotensin with antipsychotic and pro-cognitive effects: results of the pilot clinical trial

To evaluate the psychotropic specific spectrum activity of the novel peptide drug dilept and to find its effective doses in patients with schizotypal disorder. The effects of dilept were studied in 25 patients (33.4±10.0 years old) with schizotypal disorder (F21.3) with predominance of obsessive-compulsive, hypochondriac, phobic symptoms, mild cognitive impairment and negative symptoms. Patients were treated with dilept 60, 120 and 200 mg daily for 14 days as monotherapy (with allowance of phenazepam up to 2 mg single doses for insomnia and anxiety) followed by combined treatment with phenazepam in the case of insufficient effectiveness of dilept monotherapy. The Positive and Negative Syndrome scale (PANSS), Psychopathological Symptom Severity scale, Clinical Global Impression scale (CGI) and Wechsler Adult Intelligence scale (WAIS-R) were used as outcome measures. Dilept demonstrated the unique spectrum of psychotropic activity: antipsychotic with stimulating action, favorable effect on negative symptoms and cognitive dysfunction. Treatment action was the most evident when dilept was used in the dose 200 mg/day. There was no evidence of any side-effects known to be typical for antipsychotics. The efficacy of dilept and phenazepam combination is dependent on dilept's antipsychotic and pro-cognitive effects, while benzodiazepine lacks these effects.

Estimation of the Effective Dose for Patients Undergoing PA Chest X-Ray Examination in Selected Hospitals of Al Najaf Governorate-Iraq

Estimation of the Effective Dose for Patients Undergoing PA Chest X-Ray Examination in Selected Hospitals of Al Najaf Governorate-Iraq

Evaluation of effective and peak skin dose of patients undergoing interventional cardiology procedures

Introduction: Interventional cardiology procedures result in substantial patient radiation dose due to prolonged fluoroscopy time and radiographic exposure. These procedures not only lead to significant effective doses for the patient but also can potentially cause deterministic effects on the patient’s skin. The aim of this study is to investigate the effective dose and peak skin dose(PSD) of patients during frequently performed cardiology procedures as: coronary angiography(CA) and combined – coronary angiography and percutaneous intervention(CA + PCI) and to evaluate if there is a chance of getting a skin injuries.

57 Calculation of organ dose for pediatric patients undergoing computed tomography examinations: A software comparison

Introduction. The increased number of performed ’Computed Tomography (CT)’ examinations raise public concerns regarding associated stochastic risk to patients. Pediatric patients are more susceptible to radiation-induced risks than are adults owing to their rapidly growing tissues. We developed a Dose Archiving and Communication System that gives multiple dose indexes (organ dose, effective dose, and skin-dose mapping) for patients undergoing radiological imaging exams. The aim of this study was to compare the organ dose values given by our software for pediatric patients undergoing CT exams with those of another software named VirtualDose.

Radiation Dose and Lifetime Risk of Cancer Incidence and Mortality in Patients Undergoing 16 Slice CT Emergency Examinations

In this paper, we evaluate the patients effective and organ radiation dose in different CT emergency procedures and the associated lifetime risk of cancer incidence and mortality. The data were collected from 150 CT examinations. For each examination, we have collected CT exposure parameters including the number of series, tube voltage, various tube current values, patient age, gender, scan rotation time, slice width, number of slices, pitch, scan length, CT dose index (CTDIvol) and the Dose Length Product (DLP). Effective and organ doses were evaluated using DLP and k Coefficients from the European Guidelines and CT-Expo Software. Lifetime risk of cancer incidence and mortality were estimated using BEIR VII report conversion factors.

Intraoperative radiation exposure in hip arthroscopy: a systematic review.

Fluoroscopy is used in hip arthroscopy (HA) for portal placement, instrument localisation, and guidance in bony resection. The recent increase in arthroscopic hip procedures may place patients and surgeons at risk for increased radiation exposure and radiation-induced complications. The purpose of the current systematic review was to assess intraoperative radiation exposure in HA. The systematic review was conducted according to PRISMA guidelines; inclusion criteria were studies assessing radiation exposure in HA. 9 studies including 994 patients were included. Mean age was 38.6 years and 48% (436 of 906) were female. Mean time of fluoroscopy exposure was 0.58 minutes. Dose area product was 129.5 cGycm2. Mean intraoperative absorbed radiation dose studies was 12.6 mGy. Mean intraoperative effective dose was 0.48 mSv. The mean occupational exposure to the surgeon per case was 0.0031 mSv. Higher patient body mass index (BMI) correlated to greater patient effective and cumulative dose (p < 0.05, r = 0.404), and greater occupational exposure (p < 0.001, r = 0.460). Increasing surgeon experience decreased fluoroscopy time (p = 0.039) and radiation dose (p = 0.002). Radiation dose and effective dose were well under the thresholds for deterministic effects (2 Gy) and annual radiation exposure for occupational workers (20 mSv). Intraoperative radiation exposure to patients and surgeons is within acceptable annual radiation limits. Ensuring careful selection of perioperative imaging modalities, proper protective shielding, specifically the use of leaded eyeglasses, and optimal C-arm positioning are key strategies to reduce radiation exposure to patients and surgeons alike.

Artificial intelligence evaluation of simulated phantom lung nodules with different pre-adaptive iteration techniques

Objective: To investigate the detection rate of pulmonary nodules and the accuracy of automated measurement in chest simulation phantom by artificial intelligent computer-aided detection of pulmonary nodules with different pre-adaptive iterative techniques (ASIR-V) in wide-spectrum CT scanning. Methods: Sixteen pulmonary nodules with different diameters, densities and shapes were placed in the chest simulation phantom from December 2017 to March 2018. The weight of ASIR-V was set at 0%, 20%, 30%, 40% and 50% respectively by using Revolution CT broadband energy spectrum scanning protocol. Spearman correlation analysis was used to analyze the dose volume CT dose index (CTDIvol) and dose length product (DLP) of each group. Scanning data were imported into Tuma Shenwei artificial pulmonary nodule analysis software to evaluate the nature of the detected nodules, and ICC was used to detect the differences among groups. Results: With the increase of ASIR-V weight, the effective dose of patients decreased gradually. CTDIvol of five groups of radiation dose volume CT dose index was 7.93, 7.24, 5.85, 5.15, 3.76 mGy,dose-length product DLP was 379, 346, 280, 246, 179 mGy·cm.There was a linear negative correlation between ASIR-V weights and CTDIvol as well as DLP, r value was-0.969, P<0.01.There was no significant difference in the detection rate of pulmonary nodules between AI and physicians (P>0.05). There was high intraclass correlation coefficients for the diameter, volume, CT value and malignant percentage of pulmonary nodules (ICCs:0.981-1.000). Conclusions: Radiation dose of unenhanced chest CT scan using wide detector spectral imaging decreased with the increasing of preset ASIR-V. Lung nodule detection rate and evaluation performance can be maintained well by using ASIR-V reconstructions at lower radiation dosage.

Achieving the Lowest Effective Antipsychotic Dose for Patients with Remitted Psychosis: A Proposed Guided Dose-Reduction Algorithm.

Continuing antipsychotic treatment in patients with schizophrenia under clinical remission remains controversial. Even though the mainstream opinion declares an outweighed balance against medication discontinuation, recent reviews and critiques suggest that some patients may remain symptom free and well functioning after stopping antipsychotics, but few predictors can identify who can try medication discontinuation, whilst no guidelines exist for reducing medication to reach the lowest effective dose safely. Analyzing the findings from studies employing different methodologies, adopting evidence from pharmacodynamic research, and observing dose reduction in stable patients, as well as taking inspiration from the metaphor of the Cantor set in natural philosophy, we introduce an alternative solution and propose a guided dose-reduction algorithm that follows a set of clear precautions and instructions. The algorithm recommends only a fraction (no more than 25%) of the dosage to be reduced at a time, with at least a 6-month stabilization period required before reducing another 25% of the dose. Patients are empowered to actively participate in decision making when they are ready for further dose tapering, or should they retreat to a previous dosage if warning signs of a relapse re-emerge. An intermittent or irregular dosing schedule can be used to adapt this algorithm to real-world practice. Our preliminary findings suggest that patients with remitted psychosis can do well along this path. We anticipate that this approach can help optimize the risk-benefit ratio and instill a hope in patients with schizophrenia that they can maintain in stable remission under a lower antipsychotic dose without an increased risk of relapse.

Clinical Implication of Dosimetry of Computed Tomography- and Fluoroscopy-Guided Intrathecal Therapy With Nusinersen in Adult Patients With Spinal Muscular Atrophy.

Background: Spinal muscular atrophy (SMA) is a genetic disorder that leads to progressive tetraparesis. Nusinersen is the first approved drug for the treatment of SMA and is administered via intrathecal injections. Neuromyopathic scoliosis and spondylodesis can impede lumbar punctures, thus necessitating the use of radiological imaging. Furthermore, dosimetry of this potentially lifelong therapy should be supervised.Methods: Fluoroscopy-assisted or computed tomography (CT)-guided intrathecal injections of nusinersen were performed in adult patients with SMA type 2 and 3. The mean effective dose was compared in patients with and without spondylodesis as well as in those with SMA type 2 and 3. The dosimetry was analyzed in relation to the motor function evaluated with the Revised Upper Limb module (RULM) score and the Hammersmith Functional Motor Scale-Expanded (HFMSE) score.Results: Fifteen patients with SMA type 2 and 3 underwent radiological imaging-assisted intrathecal injections. The mean effective dose per CT-guided injection per patient was 2.59 (±1.67) mSv (n = 12). The mean dose area product (DAP) per fluoroscopy-guided injection per patient was 200.48 (±323.67) μGym2 (n = 3). With increase in the number of injections, the effective dose (r = −0.23) (p < 0.05) and the DAP (r = −0.09) (p > 0.05) decreased. The mean effective dose in 4 patients without spinal fusion (SMA type 2) was 1.39 (±0.51) mSv, whereas that in 8 patients with spondylodesis (SMA type 2 and 3) was 3.21 (±1.73) mSv. The mean effective dose in 5 SMA type 2 patients with spondylodesis was 2.68 (±1.47) mSv (n = 5) and in 3 SMA type 3 patients was 4.00 (±1.82) mSv. Dosimetry did not show significant correlation with the clinical severity of the disease (RULM score: r = −0.045, p > 0.05 and HFMSE score: r = −0.001, p > 0.05).Conclusions: In SMA type 2 and 3 patients undergoing radiological imaging-assisted injections, the effective dose and DAP decreased during therapy with nusinersen. The mean effective dose in patients with spondylodesis was higher than that in patients without spondylodesis. Dosimetry should be monitored carefully in order to detect and prevent unnecessary radiation exposure.