Patient Dose Reduction Research Articles

Hematologic adverse events following palbociclib (PAL) dose reduction in patients (pts) with hormone receptor‒positive (HR+)/human epidermal growth factor receptor 2‒negative (HER2‒) advanced breast cancer (ABC): Pooled analysis from randomized phase 2 and 3 studies.

1060Background: A previous pooled analysis showed that 36.9% of pts receiving PAL required dose reduction, most occurring during the first 6 mo of treatment and with decreasing frequency during sub...

Decreased operator X-ray exposure by optimized fluoroscopy during radiofrequency ablation of common atrial flutter.

To evaluate operator and patient irradiation during radiofrequency ablation (RFA) of common atrial flutter (AF) using three different fluoroscopy settings. A total of 38 patients who underwent RFA of AF with three different fluoroscopy settings (low dose, standard dose and collimated field) were included. Twelve patients (11 men, 1 woman; mean age, 67±12 [SD]years) were included in the low dose group (3.75 frames per second), 13 patients (13 men; mean age, 66±8 [SD]years) were included in the standard dose group (7.5 frames per second) and 13 patients (13 men; mean age, 71±12 [SD]years) were included in the collimated field group (7.5 frames per second). Operator and patient exposure were compared between groups. No differences in procedure time and radiation exposure were found between the three groups. In the low dose group, mean operator X-ray exposures of eye-lens (4.7±2.9 [SD]μSv/h; range: 0.9-10.5μSv/h), whole body (1.6±1.2 [SD]μSv/h; range 0.5-3.6μSv/h) and hand skin (11.1±10.8 [SD] μSv/h; range 2.4-35.4μSv/h) were significantly lower than those in the standard dose group (P<0.001). Significant patient dose reduction was found between low dose group (0.7±0.4 [SD]Gy/h; range: 0.3-0.9Gy/h) and standard (1.7±0.5 [SD]Gy/h; range: 0.8 to 3.9Gy/h) and collimated (1.8±0.5 [SD]Gy/h; range: 0.7-3.0Gy/h) groups (P<0.01). The use of a low dose setting (3.75 f/s) during fluoroscopy dramatically reduces operator's irradiation during RFA of AF by a mean of 90%.

Chemotherapy for metastatic colon cancer: No effect on survival when the dose is reduced due to side effects

Background5-Fluorouracil (5FU), Folinic acid (FA), and Oxaliplatin (FOLFOX) or 5FU, FA, and Irinotecan (FOLFIRI) are standard regimens for palliative chemotherapy of metastatic colon cancer. Since data showing the influence of dose reduction in palliative treatment are rare, the objective of this single center, retrospective study was to further characterize the influence of dose reduction on efficacy of these therapeutic regimens.MethodsOne hundred nine patients, diagnosed with stage IV colon cancer between 2004 and 2012 and receiving palliative first-line chemotherapy with either FOLFOX or FOLFIRI regimens in our outpatient clinic were analyzed for treatment efficacy. Patients who received dose reductions due to side effects usually received doses of 80% or lower of per protocol dose. Survival data were obtained from the Regensburg Tumor Registry. Survival analysis was performed using Kaplan-Meier statistical analysis and multivariable analysis.ResultsA dose reduction due to side effects was necessary in 46 (42%) patients. Dose reduction was independent of age. Major reasons for dose reduction were neutropenia (30%) followed by polyneuropathy (16%) and diarrhea (14%). Dosage was more often reduced in patients receiving FOLFOX based therapy. Comparison of patients with dose reduction versus patients with full dosage showed no significant difference on overall survival (p = 0.430). Subgroup analysis revealed dose reduction in patients with N2 stage disease was associated with improved survival. Patients who underwent dose reduction received more cycles of chemotherapy (13.7 vs. 10.8 cycles) and cumulative dosage was similar in both groups.ConclusionContrary to our expectations, the need to reduce chemotherapy dosage due to side effects does not indicate a worse prognosis in our retrospective analysis. We believe this can in part be explained by better adaption to interindividual pharmacokinetics and longer time of treatment.

Retrospective analysis of the impact of anthracycline dose reduction and chemotherapy delays on the outcomes of early breast cancer molecular subtypes

BackgroundThe objective of study was to determine the effect of anthracycline dose reduction and chemotherapy delays on 5-year overall survival in patients with stage I-III breast cancer, to establish the impact of molecular subtypes on the anthracycline modification effects and to analyze reasons for such chemotherapy scheme modifications.MethodsMedical records of patients with stage I-III breast cancer were reviewed. Inclusion criteria involved stage I- III breast carcinoma; radical surgery performed and 4 courses of AC regimen (doxorubicin and cyclophosphamide), or at least 6 courses of FAC regimen (fluorouracil, doxorubicin and cyclophosphamide) completed; no neoadjuvant chemotherapy applied; no taxane group medications administered; medical records maintain comprehensive data on treatment and follow-up. 5- year overall survival were analyzed using Kaplan-Meier and Cox proportional hazards models.ResultsSignificant 3.17 times higher death risk at 5 year period in patients who experienced anthracycline dose reduction compared with patients who did not experience any modifications was established (HR = 3.17, 95% CI 1.7–5.9, p < 0.001). Increased death risk in patients who experienced both chemotherapy dose reduction and treatment delays compared with patients who did not experience any modifications was also established (HR = 2.76, 95% CI 1.3–5.6, p < 0.05). 5- year overall survival was affected by anthracycline dose reduction by more than 15% in ER-HER2- group (80% v. 55.6%, p = 0.015), ER + HER2- group (90.7% v. 64.9%, p < 0.01) and ER+/-HER2+ group (100% v. 84.4%, p = 0.019). 5-year overall survival was affected by chemotherapy delays more than 2 cycles in ER-HER2- group (79.2% v. 51.4%, p = 0.002), ER + HER2- group (86.3% v. 58.8%, p = 0.014) and there was no difference in ER+/-HER2+ group. Main reasons for chemotherapy scheme modifications (in decreasing order) were the following: neutropenia, modifications with no objective medical reasons, thrombocytopenia, anaemia, fatigue, infection.ConclusionsAnthracycline dose reduction in patients with stage I- III breast cancer were associated with higher mortality risk and significantly decreased 5- year absolute survival in all molecular subtypes. Chemotherapy delays alone were not associated with decreased survival only in HER2 positive subtype. The most common reason for dose reduction or chemotherapy delays was neutropenia.

PO-0968: Dual energy and iterative CBCT reconstruction allows reducing patient dose

PO-0968: Dual energy and iterative CBCT reconstruction allows reducing patient dose

204 (PB-105) - The effect of surveillance for symptomatic toxicities with real-time clinician reporting on dose reduction, hospitalization and febrile neutropenia in Danish breast cancer patients—a population-based cluster randomized trial using the Patient-Reported Outcomes version of Common Terminology Criteria for Adverse Events (PRO-CTCAE)

204 (PB-105) - The effect of surveillance for symptomatic toxicities with real-time clinician reporting on dose reduction, hospitalization and febrile neutropenia in Danish breast cancer patients—a population-based cluster randomized trial using the Patient-Reported Outcomes version of Common Terminology Criteria for Adverse Events (PRO-CTCAE)

Population PK and Exposure-Response Relationships for the Antibody-Drug Conjugate Brentuximab Vedotin in CTCL Patients in the Phase III ALCANZA Study.

The antibody–drug conjugate (ADC) brentuximab vedotin consists of the CD30‐directed antibody attached to the microtubule‐disrupting agent monomethyl auristatin E (MMAE). In pharmacokinetic models, including data from six studies (380 patients with classical Hodgkin's, systemic anaplastic large‐cell, and cutaneous T‐cell (CTCL) lymphomas), lower clearance of ADC and modestly higher ADC exposure in CTCL patients did not translate into higher MMAE exposure. In CTCL patients from the phase III ALCANZA study (n = 66), improved progression‐free survival with brentuximab vedotin vs. controls was not related to ADC exposure. ADC exposure was a predictor of grade ≥3 treatment‐emergent adverse events (TEAEs). Results support the consistent benefit observed with brentuximab vedotin 1.8 mg/kg every 3 weeks across the range of exposures in ALCANZA and support dose reductions in patients experiencing TEAEs at the starting dose.

Chemotherapy dose reductions in obese patients undergoing adjuvant chemotherapy for colorectal cancer: secondary analyses of trial data and the Greater Manchester and Cheshire Cancer Network Audit.

763 Background: In patients with stage II/III colorectal cancer receiving adjuvant chemotherapy, doses are calculated using body surface area (BSA) but often capped at BSA &gt; 2.0. Dose capping might be a mechanism of reported poorer survival in obese patients. We aimed to investigate the different dosing schedules across BMI categories, using trial and ‘real world’ audit datasets, and determine its impact upon overall survival. Methods: Data was accessed for 1122 patients from the control arm of the MOSAIC trial (accessed via the Data Project Sphere) and 327 patients from the Greater Manchester and Cheshire Cancer Network (GMCCN) audit. Pearson’s χ2 and correlation coefficient were used to assess the relationship between BMI (expressed as normal, overweight and obese: and as continuous, respectively) and dose reductions. A multiple logistic regression model was constructed to compare the odds of receiving dose reductions in each BMI category. 4-year overall survival was calculated for each BMI category and dose status. Results: In MOSAIC, there were increasing dose reductions by BMI category: normal, 3%; overweight, 5%; and obese, 11%, with similar patterns in the GMCCN OxMdG group. Obese patients in MOSAIC and the GMCCN OxMdG group had 3- and 12-fold higher odds (OR = 3.4 and 12.5, CI = 1.6-7.0 and 2.0-78.1), respectively, of receiving dose reductions. However, these differences did not translate to differences in overall survival by BMI category or dose status. Conclusions: In our investigated datasets, there appears to be a relationship between increasing BMI and dose reductions, though it is modest and does not manifest as a detrimental influence on overall survival. Our findings agreed with other studies performed using stage IV cancer patients, although the relationship between increasing BMI and dose reductions is more prominent in patients with metastatic disease. Investigating other outcome measures such as cancer-specific survival and chemotherapy related toxicity is required for clarity.

Low-dose Lung Cancer Screening at an Academic Medical Center: Initial Experience and Dose Reduction Strategies

Implementation of low dose computed tomography (LDCT) lung cancer screening programs has followed the demonstration of reduced lung cancer mortality in the National Lung Screening Trial and subsequent consensus screening recommendations. Here we aim to assess the initial results of a screening program at an academic medical center, to discuss the challenges of implementing such a program, and suggest strategies for reducing patient dose. Retrospective review of all patients who underwent LDCT lung cancer screening at our institution between March 2015 and July 2016 was performed to assess the lung cancer detection rate, the spectrum of imaging findings (nodule or mass characteristics, degree of emphysema, etc.), and patient radiation dose indices. A total of 272 patients were screened during the study period. Approximately 50% (n = 135) were women. The lung cancer detection rate was 2.2% (n = 6). One patient underwent chemoradiation therapy, whereas the remainder underwent uneventful thoracoscopic resection. Approximately, 80% of screened patients met United States Preventative Services Task Force criteria for LDCT screening. The median pack-years of smoking was 42 pack-years. The mean volume CT dose index for the screening CTs was 3.12 mGy. Utilizing tube current modulation and iterative reconstruction, where available, resulted in lower patient doses. Initial LDCT lung cancer screening at our institution yielded results similar to those of the National Lung Screening Trial. Thorough prescreening evaluation, joint decision-making, centralized coordination of screening-related care, and patient size conscious scanning protocols are critical elements of a safe and successful lung cancer screening program.

Dose adjustment of cisplatin, etoposide, and ifosfamide according to kidney function: a retrospective analysis and implications for medication safety.

Clearance of cisplatin, etoposide, and ifosfamide depends on kidney function and dosages should be adjusted in patients with renal impairment. However, there is still limited data on the adherence of physicians to dosing recommendations for these drugs in cancer patients with renal impairment. Three thousand four hundred forty-eight prescriptions to 369 patients, treated in the Comprehensive Cancer Center of a German university hospital, were retrospectively evaluated. The administered relative doses of cisplatin, etoposide, and ifosfamide were compared with relative doses recommended at the time of prescription according to the patients' creatinine clearance. Cisplatin is contraindicated according to two German summary of product characteristics (SmPC) in patients with a creatinine clearance < 60mL/min. Nevertheless, 37 cisplatin prescriptions were made for this group of patients (i.e., 2.0% of all cisplatin prescriptions). According to one German SmPC (valid in the year of data analysis), etoposide dosage should be reduced in patients with a creatinine clearance from 15 to 50mL/min, while it is contraindicated below 15mL/min. Thirteen etoposide prescriptions were without dose reduction in patients with creatinine clearance from 15 to 50mL/min (1.5% of all etoposide prescriptions); one patient received etoposide with creatinine clearance below 15mL/min. In 8.9% of ifosfamide prescriptions, patients did not receive a reduced dose in spite of respective recommendations. Dosages of cisplatin, etoposide, and ifosfamide are not always adjusted as recommended in patients with renal impairment. Consistent international dosing recommendations (e.g., in SmPCs), preferentially included in clinical decision support systems, should be developed to tackle this problem.

Abstract ID: 176 Geant4 implementation of inter-atomic interference effect in small-angle coherent X-ray scattering for materials of medical interest

Advanced applications of digital mammography such as dual-energy and tomosynthesis require multiple exposures and thus deliver higher dose compared to standard mammograms. A straightforward manner to reduce patient dose without affecting image quality would be removal of the anti-scatter grid, provided that the involved reconstruction algorithms are able to take the scatter figure into account [1]. Monte Carlo simulations are very well suited for the calculation of X-ray scatter distribution and can be used to integrate such information within the reconstruction software. Geant4 is an open source C++ particle tracking code widely used in several physical fields, including medical physics [2,3]. However, the coherent scattering cross section used by the standard Geant4 code does not take into account the influence of molecular interference. According to the independent atomic scattering approximation (the so-called free-atom model), coherent radiation is indistinguishable from primary radiation because its angular distribution is peaked in the forward direction. Since interference effects occur between x-rays scattered by neighbouring atoms in matter, it was shown experimentally that the scatter distribution is affected by the molecular structure of the target, even in amorphous materials. The most important consequence is that the coherent scatter distribution is not peaked in the forward direction, and the position of the maximum is strongly material-dependent [4]. In this contribution, we present the implementation of a method to take into account inter-atomic interference in small-angle coherent scattering in Geant4, including a dedicated data set of suitable molecular form factor values for several materials of clinical interest. Furthermore, we present scatter images of simple geometric phantoms in which the Rayleigh contribution is rigorously evaluated.

The utility of digital breast tomosynthesis in axillary lymph node post clip mammography

Regional breast cancer staging with axillary lymph node biopsy has been in the spotlight in recent years following results of the American College of Surgeons Oncology Group (ACOSOG) Z1011 trial. Subsequent studies have demonstrated that clip marker placement in biopsy proven metastatic axillary lymph nodes aids in targeted axillary lymph node dissection, ensuring excision of known metastatic disease and reducing the false negative rate of sentinel lymph node biopsy. We believe the use of DBT for documentation of axillary lymph node clip marker placement presents an opportunity to expand on the established benefits of this new technology. DBT can provide three-dimensional assessment of axillary clip marker placement, assists future follow-up and localization, improves workflow efficiency, helps potentially reduce patient dose and enhances the patient experience.

Single-Arm Phase 2 Trial of Elective Nodal Dose Reduction for Patients With Locoregionally Advanced Squamous Cell Carcinoma of the Head and Neck

To evaluate a novel chemoradiation therapy (CRT) regimen for patients with squamous cell carcinoma of the head and neck (SCCHN) incorporating a lower intensity modulated radiation therapy dose to electively treated neck lymph nodes than is currently standard. Eligible patients had locally advanced SCCHN of the oral cavity, oropharynx, larynx, or hypopharynx. The 7-week CRT course consisted of weekly cisplatin at 35mg/m2 concurrently with sequential-boost intensity modulated radiation therapy: 36Gy to high- and low-risk planning target volumes followed by a sequential boost to the high-risk planning target volume to 70Gy. The primary endpoint was elective nodal failure. Secondary endpoints were survival, toxicity, feeding tube duration, and quality of life evaluated by the FACT-HN and QOL-RTI surveys. Between 2011 and 2014, 54 patients were enrolled, 31 (57%) of whom had human papillomavirus (HPV)-positive disease.Of the patients, 35 (65%) had stage IVa disease. The median follow-up period for survivors was 36months (range, 12-66months). Elective nodal failure did not develop in any patient. The actuarial 3-year survival rate for the entire cohort was 91% (95% confidence interval [CI] 0.79-0.96); for the HPV-negative group, 85% (95% CI 0.61-0.95); and for the HPV-positive group, 96% (95% CI 0.77-0.99). Common grade 3 toxicities were dysphagia (79%), mucositis and/or stomatitis (41%), nausea (20%), xerostomia (13%), vomiting (11%), and neutropenia (10%). The median feeding tube duration was 142days. Patient FACT-HN scores were higher at 3, 6, and 12months versus at the end of treatment (P < .0001). Total FACT-HN scores returned to pretreatment baseline by 6months. Overall QOL-RTI scores were lower from pretreatment to the end of treatment through 12months (P = .0001). This CRT regimen for patients with advanced SCCHN demonstrated the potential feasibility of reducing the elective dose to the neck, a topic that requires additional study in future clinical trials.

Efficacy and safety of adrenocorticotropic hormone gel in refractory dermatomyositis and polymyositis

AimTo evaluate the efficacy, safety, tolerability and steroid-sparing effect of repository corticotropin injection (RCI), in an open-label clinical trial, in refractory adult polymyositis (PM) and dermatomyositis (DM).MethodsAdults with refractory PM...

The benefits of folic acid-modified gold nanoparticles in CT-based molecular imaging: radiation dose reduction and image contrast enhancement

X-ray computed tomography (CT) requires an optimal compromise between image quality and patient dose. While high image quality is an important requirement in CT, the radiation dose must be kept minimal to protect the patients from ionizing radiation-associated risks. The use of probes based on gold nanoparticles (AuNPs) along with active targeting ligands for specific recognition of cancer cells may be one of the balanced solutions. Herein, we report the effect of folic acid (FA)-modified AuNP as a targeted nanoprobe on the contrast enhancement of CT images as well as its potential for patient dose reduction. For this purpose, nasopharyngeal KB cancer cells overexpressing FA receptors were incubated with AuNPs with and without FA modification and imaged in a CT scanner with the following X-ray tube parameters: peak tube voltage of 130 KVp, and tube current–time products of 60, 90, 120, 160 and 250 mAs. Moreover, in order to estimate the radiation dose to which the patient was exposed during a head CT protocol, the CT dose index (CTDI) value was measured by an X-ray electrometer by changing the tube current–time product. Raising the tube current–time product from 60 to 250 mAs significantly increased the absorbed dose from 18 mGy to 75 mGy. This increase was not associated with a significant enhancement of the image quality of the KB cells. However, an obvious increase in image brightness and CT signal intensity (quantified by Hounsfield units [HU]) were observed in cells exposed to nanoparticles without any increase in the mAs product or radiation dose. Under the same Au concentration, KB cells exposed to FA-modified AuNPs had significantly higher HU and brighter CT images than those of the cells exposed to AuNPs without FA modification. In conclusion, FA-modified AuNP can be considered as a targeted CT nanoprobe with the potential for dose reduction by keeping the required mAs product as low as possible while enhancing image contrast.

Impact of Opioid Dose Reduction and Risk Mitigation Initiatives on Chronic Opioid Therapy Patients at Higher Risk for Opioid-Related Adverse Outcomes

We aimed to determine if opioid risk reduction initiatives including dose reduction and risk mitigation strategies for chronic noncancer pain patients receiving chronic opioid therapy (COT) had a differential impact on average daily opioid doses of COT patients at higher risk for opioid-related adverse outcomes compared with lower-risk patients. Interrupted time series. Group Health Cooperative (GH), a health care delivery system and insurance within Washington State, between 2006 and 2014. GH enrollees on COT defined as receiving a supply of 70 or more days of opioids within 90 days using electronic pharmacy data for filled prescriptions. We compared the average daily morphine equivalent doses (MED) of COT patients with and without each of the following higher-risk characteristics: mental disorders, substance use disorders, sedative use, and male gender. In all four pairwise comparisons, the higher-risk subgroup had a higher average daily MED than the lower-risk subgroup across the study period. Adjusted for covariates, modest differences in the annual rate of reduction in average daily MED were noted between higher- and lower-risk subgroups in three pairwise comparisons: those with mental disorders vs without (-8.2 mg/y vs -5.2 mg/y, P = 0.005), with sedative use vs without (-9.2 mg/y vs -5.8 mg/y, P = 0.004); mg), in men vs women (-8.8 mg/y vs -5.9 mg/y, P = 0.01). Using clinical policy initiatives in a health care system, dose reductions were achieved among COT patients at higher risk for opioid-related adverse outcomes that were at least as large as those among lower-risk patients.

Ribociclib plus letrozole versus letrozole alone in patients with de novo HR+, HER2\u2212 advanced breast cancer in the randomized MONALEESA-2 trial

PurposeDetermine the efficacy and safety of first-line ribociclib plus letrozole in patients with de novo advanced breast cancer.MethodsPostmenopausal women with HR+ , HER2− advanced breast cancer and no prior systemic therapy for advanced disease were enrolled in the Phase III MONALEESA-2 trial (NCT01958021). Patients were randomized to ribociclib (600 mg/day; 3 weeks-on/1 week-off) plus letrozole (2.5 mg/day; continuous) or placebo plus letrozole until disease progression, unacceptable toxicity, death, or treatment discontinuation. The primary endpoint was investigator-assessed progression-free survival; predefined subgroup analysis evaluated progression-free survival in patients with de novo advanced breast cancer. Secondary endpoints included safety and overall response rate.ResultsSix hundred and sixty-eight patients were enrolled, of whom 227 patients (34%; ribociclib plus letrozole vs placebo plus letrozole arm: n = 114 vs. n = 113) presented with de novo advanced breast cancer. Median progression-free survival was not reached in the ribociclib plus letrozole arm versus 16.4 months in the placebo plus letrozole arm in patients with de novo advanced breast cancer (hazard ratio 0.45, 95% confidence interval 0.27–0.75). The most common Grade 3/4 adverse events were neutropenia and leukopenia; incidence rates were similar to those observed in the full MONALEESA-2 population. Ribociclib dose interruptions and reductions in patients with de novo disease occurred at similar frequencies to the overall study population.ConclusionsRibociclib plus letrozole improved progression-free survival vs placebo plus letrozole and was well tolerated in postmenopausal women with HR+, HER2− de novo advanced breast cancer.

Decrease in salivary cortisol levels after glucocorticoid dose reduction in patients with adrenal insufficiency: A prospective proof-of-concept study.

Patients with adrenal insufficiency (AI) require lifelong glucocorticoid (GC) replacement therapy. Cortisol measurement in saliva is increasingly being used: we assessed salivary cortisol rhythm in outpatients with AI, to provide new insights regarding the management of GC treatment. Nineteen AI outpatients collected six saliva samples from awakening (Fa , before taking the morning GC therapy), during the day (F1.5h , F6h before the afternoon GC dose, F8.5h , F12h ) until bedtime (Fb ). We measured daily cortisol exposure by calculating the area under the curve (AUCFa→Fb ). Saliva samples were collected at baseline and one year after GG dose reduction (by at least 5mg of hydrocortisone). Hydrocortisone equivalents decreased from median 25mg/d (baseline, interquartile range IQR 20-27.5) to 15mg/d (IQR 15-20, P<.01). As expected, we observed a reduction in both daily cortisol exposure (AUCFa→Fb 23982nmol·h/L, IQR 12635-45369, to 14689nmol·h/L, IQR 7168-25378, P<.001) and salivary cortisol levels at F6h (24.8nmol/L, IQR 20.1-35.7, to 21nmol/L, IQR 8.7-29.2, P<.05) and Fb (8.7nmol/L, IQR 3.4-20.2, to 3.7nmol/L, IQR 3.0-5.8, P<.05). None of the patients developed signs or symptoms consistent with AI after GC reduction. Median diastolic blood pressure (DPB) values fell from baseline to the end of follow-up (87.5mm Hg, IQR 80-90, to 80mm Hg, IQR 80-85, P<.05). The AUCFa→Fb of patients at baseline was above the reference value (90th percentile of controls) in 12 patients (60%); after the dosage reduction, 30% of patients normalized their daily cortisol exposure (AUCFa→Fb ). The reduction in GC treatment in patients with AI resulted in better control of daily cortisol rhythm, measured with salivary cortisol, and in an improvement of DPB. Further studies are needed to ascertain if salivary cortisol could be used as a biomarker to manage GC replacement therapy.

Iterative reconstruction and automatic tube voltage selection reduce clinical CT radiation doses and image noise

IntroductionComputed Tomography (CT) use has increased in recent years with trends indicating increasing population doses as a result. Optimization of clinical radiation doses through technological developments has demonstrated potential to reduce patient dose from CT. This study aimed to quantify these dose reductions across a large clinical cohort. MethodsPatient cohort was divided into three groups, assigned by CT optimisation technique. Group one underwent scanning with automated tube current modulation only. Group two underwent scanning with automated tube current modulation and iterative reconstruction and group three underwent scanning with automated tube current modulation, iterative reconstruction and automatic tube voltage modulation. Patient dose length product doses were retrospectively collected for the three groups. Clinical radiation doses between the groups were compared for four common CT examinations (Brain, pulmonary angiography, abdomen and thorax abdomen pelvis scans). ResultsOf 4011 patients, group one comprised of 1643 patients (40.96%), group two 1077 patients (26.85%) and group three 1291 patients (32.19%). No differences were found when comparing AP diameter between groups (p ≥ 0.05). Statistically significant dose reductions of 16–31% were achieved using iterative reconstruction alone (p = 0.001) and 24–42% with both iterative reconstruction and automatic tube voltage selection (p = 0.001). Objective noise improved when iterative reconstruction was used (p < 0.05). ConclusionThe application of optimization software confers significant dose savings during routine clinical CT examinations. Figures are based on a large clinical cohort, with equipment, staff and procedural protocols remaining consistent throughout. Dose reductions are likely to reflect the clinical dose reducing potential of the optimization software investigated.

Estimation and comparison of the radiation effective dose during coronary computed tomography angiography examinations on single-source 64-MDCT and dual-source 128-MDCT

Goal. To estimate and compare the radiation dose associated with coronary computed tomography angiography (CCTA) examinations on two multi-detector CT scanners (MDCT), 64-MDCT and 128-MDCT, in daily practice. Methods. Scan parameters of 90 patients undergoing retrospective electrocardiographic gating spiral CCTA exam were recorded during a period on a single-source 64-MDCT and a dual-source 128-MDCT, and average scan parameters were derived that were used for dosimetry. The computed tomography dose index (CTDI) with a pencil ionisation chamber and polymethyl methacrylate body phantom with diameter of 32 cm was measured on both scanners. The dose–length product (DLP) was calculated and the DLP to effective dose conversion factor (for chest scan at 120 kV of 0.014 mSv mGy–1 cm–1) was used to estimate effective dose (ED). Results. Patients’ heart rate, scan length, pitch factor, CTDIv, DLP and ED for 128-MDCT were 64 (5) (beats min–1), 161 (10) (mm), 0.26, 47 (12) (mGy), 769 (212) (mGy cm) and 10.3 (3.1) (mSv), respectively [mean (one standard deviation)]. Patients’ heart rate, scan length, pitch factor, CTDIv, DLP and ED for 64-MDCT were 60 (7) (beats min–1), 172 (14) (mm), 0.2, 60 (6) (mGy), 1068 (98) (mGy cm) and 14.9 (1.4) (mSv), respectively. Conclusion. Our results indicated that the CTDIv, DLP and the effective dose with 128-MDCT is significantly lower than with 64-MDCT (p < 0.05). As differences between the exposure parameter mAs on two CT scanners was not significant (p > 0.05) and the kV was constant for both scanners (120 kV), the differences resulted from a shorter scan length on the 128-MDCT and use of a higher pitch factor (0.26 and 0.2 in the 128-MDCT and 64-MDCT, respectively). Comparison with other published studies confirms the findings and indicates methods for reducing patient dose.