Does the textbook outcome in pancreatic surgery score after pancreaticoduodenectomy for ampullary carcinoma have prognostic value?

BACKGROUND: The value of the textbook outcome in pancreatic surgery (TOPS) score, a composite measure of surgical performance for quality assurance, was evaluated in a South African tertiary hospital cohort of pancreaticoduodenectomies (PD) performed for adenocarcinoma of the ampulla of Vater (AAV). METHODS: A review of all patients undergoing a PD for AAV at a single centre between January 1999 and December 2023 was performed. Demographic, operative, pathological and postoperative variables were recorded. Ten clinical and histological variables were used to construct a TOPS score. These included an R0 resection, no postoperative pancreatic fistula (POPF), no bile leak, no post-pancreatectomy haemorrhage, no delayed gastric emptying, no major postoperative complications (< Gr 3 Clavien-Dindo), no readmission to ICU, length of stay ≤ 10 days, no 30-day readmission or intervention and no 30-day mortality. A textbook outcome (TO) was defined as the fulfilment of all 10 variables. In patients in whom TO was not achieved, the reasons for failure were identified. In addition, the number of patients who had major complications and died were categorised as failure to rescue (FTR). RESULTS: A positive TOPS score was achieved in 27 of 79 (34.2%) patients undergoing a PD. Overall five-year survival after PD was 33.9%. TOPS conferred a significant 1-year survival benefit, 88.9% vs 66.7% (OR 4.12, 95% CI 1.08-15.67, p = 0.038). There was no significant difference in 5-year survival between TOPS and non-TOPS patients, 40.0% vs 32.4% (OR 1.39, 95% CI 0.48-3.99, p = 0.54). A POPF occurred in 31.6% patients, resulting in a significantly longer hospital admission, 17 vs 10 days (95% CI 2.66-11.34, p = 0.0019). Twenty-one (26.6%) patients developed a major complication, five of whom died (FTR = 6.3%). CONCLUSION: This study confirmed the value of TOPS as a useful measurement to assess hospital quality metrics and short-term survival after PD for AAV. One quarter of patients developed a major complication with a 6.3% FTR.

Intermediate and long-term survival prediction using prognostic scores in patients undergoing salvage TIPS for uncontrolled variceal bleeding.

BACKGROUND: This study investigated the value of prognostic scores to predict 90-day, 1-, 3- and 5-year survival after salvage TIPS (sTIPS) in patients with exsanguinating variceal bleeding who failed endoscopic intervention. METHODS: The Model for End-Stage Liver Disease (MELD), Model for End-Stage Liver Disease Sodium (MELDNa), Acute Physiology and Chronic Health Evaluation II (APACHE II) and Child-Pugh (C-P) grades and scores were calculated using Kaplan-Meier curves and Cox proportional hazards models in sTIPS patients treated between August 1991 and November 2020. RESULTS: Thirty-four patients (29 men, 5 women), mean age 52 years, SD ± 11.6 underwent sTIPS which controlled bleeding in 32 (94%) patients. Ten (29.4%) patients died in hospital at a median of 4.8 (range 1-10) days. On bivariate analysis, C-P score ≥ 10 (p = 0.017), high C-P grade (p = 0.048), MELD ≥ 15 (p = 0.010), MELD-Na score ≥ 22 (p < 0.001) and APACHE II score ≥ 15 (p < 0.001) predicted 90-day mortality. Individual clinical characteristics associated with 90-day mortality were grade 3 ascites (p = 0.029), > 10 units of blood transfused (p = 0.004), balloon tube placement (p < 0.001), endotracheal intubation (< 0.001) and inotrope support (p < 0.001). The overall 90-day, 1-, 3- and 5-year survival rates were 67.6%, 55.9%, 26.5% and 20.6% respectively. Nine patients (26.5%) were alive at a median of two years (range 1-18 years) post-TIPS. Patients with C-P grade A, C-P score < 10, MELD score < 15, MELD-Na score < 22 and APACHE II score < 15 had significantly better 90-day, 1-, 3- and 5-year survival rates. CONCLUSION: Although sTIPS controlled variceal bleeding in 94% of patients after failed endoscopic therapy, in-hospital mortality was 29% and less than one quarter were alive after five years. The selected cut-off values for the nominated scoring systems accurately predicted 90-day mortality and long-term survival.

Temporal Structures in Electron Spectra and Charge Sign Effects in Galactic Cosmic Rays.

We present the precision measurements of 11 years of daily cosmic electron fluxes in the rigidity interval from 1.00 to 41.9 GV based on 2.0×10^{8} electrons collected with the Alpha Magnetic Spectrometer (AMS) aboard the International Space Station. The electron fluxes exhibit variations on multiple timescales. Recurrent electron flux variations with periods of 27 days, 13.5 days, and 9 days are observed. We find that the electron fluxes show distinctly different time variations from the proton fluxes. Remarkably, a hysteresis between the electron flux and the proton flux is observed with a significance of greater than 6σ at rigidities below 8.5 GV. Furthermore, significant structures in the electron-proton hysteresis are observed corresponding to sharp structures in both fluxes. This continuous daily electron data provide unique input to the understanding of the charge sign dependence of cosmic rays over an 11-year solar cycle.

Factors influencing in-hospital mortality for salvage percutaneous transjugular intrahepatic portosystemic shunting in cirrhotic patients with recalcitrant variceal bleeding after failed endoscopic intervention.

BACKGROUND: Endoscopic therapy is the first-line treatment of choice for control of acute variceal bleeding (AVB). In high-risk patients with persistent AVB despite pharmacological treatment and endoscopic intervention, percutaneous transjugular intrahepatic portosystemic shunting (TIPS) provides a minimally invasive salvage method to reduce portal pressure and control bleeding. OBJECTIVES: To evaluate factors influencing in-hospital mortality after salvage TIPS (sTIPS) in patients with exsanguinating variceal bleeding despite medical treatment and endoscopic intervention. METHODS: Clinical and laboratory data were analysed in all patients treated with sTIPS following failed endoscopic therapy for AVB between August 1991 and November 2020. Factors associated with and predictors of death were determined using bivariate analysis and univariate logistic regression analysis. RESULTS: Thirty-four patients (29 men, 5 women), mean age 52 years (range 31 - 80), received sTIPS for uncontrolled (n=11) or refractory (n=23) AVB. The causes of portal hypertension were alcohol-related (n=24) and non-alcohol-related cirrhosis. Salvage TIPS controlled bleeding in 32 patients, with recurrence in 1. Ten patients died in hospital (mean 4.8 days, range 1 - 10) of liver failure (n=4), multiorgan failure (n=3), alcoholic cardiomyopathy (n=2) and uncontrolled gastric variceal bleeding (n=1). On bivariate analysis, factors associated with death were Child-Pugh (C-P) score ≥10 (p=0.006), sodium Model for End-stage Liver Disease (MELD-Na) score ≥22 (p<0.001), ≥8 units of blood transfused (p<0.001), Sengstaken-Blakemore balloon tube placement (p<0.001), endotracheal intubation (p<0.001), inotropic support (p<0.001) and endoscopically uncontrolled bleeding (p<0.001). Univariate logistic regression analysis showed that the most significant predictors of mortality were inotrope dependency (odds ratio (OR) 134; p<0.001), endotracheal intubation (OR 99; p<0.001), endoscopically uncontrolled bleeding (OR 28; p=0.001), grade 3 ascites (OR 20.9; p=0.012) and C-P grade C (OR 8.8; p=0.011). CONCLUSION: Salvage TIPS controlled variceal bleeding in 94% of patients after failed endoscopic therapy with 29% in-hospital mortality. The most significant predictors of mortality were C-P grade C, grade 3 ascites, inotrope requirement, endotracheal intubation and endoscopically uncontrolled bleeding.

Properties of Daily Helium Fluxes.

We present the precision measurement of 2824 daily helium fluxes in cosmic rays from May 20, 2011 to October 29, 2019 in the rigidity interval from 1.71 to 100 GV based on 7.6×10^{8} helium nuclei collected with the Alpha Magnetic Spectrometer (AMS) aboard the International Space Station. The helium flux and the helium to proton flux ratio exhibit variations on multiple timescales. In nearly all the time intervals from 2014 to 2018, we observed recurrent helium flux variations with a period of 27 days. Shorter periods of 9 days and 13.5 days are observed in 2016. The strength of all three periodicities changes with time and rigidity. In the entire time period, we found that below ∼7 GV the helium flux exhibits larger time variations than the proton flux, and above ∼7 GV the helium to proton flux ratio is time independent. Remarkably, below 2.4 GV a hysteresis between the helium to proton flux ratio and the helium flux was observed at greater than the 7σ level. This shows that at low rigidity the modulation of the helium to proton flux ratio is different before and after the solar maximum in 2014.

Erratum: Properties of a New Group of Cosmic Nuclei: Results from the Alpha Magnetic Spectrometer on Sodium, Aluminum, and Nitrogen [Phys. Rev. Lett. 127, 021101 (2021)].

This corrects the article DOI: 10.1103/PhysRevLett.127.021101.

Properties of a New Group of Cosmic Nuclei: Results from the Alpha Magnetic Spectrometer on Sodium, Aluminum, and Nitrogen.

We report the properties of sodium (Na) and aluminum (Al) cosmic rays in the rigidity range 2.15 GV to 3.0 TV based on 0.46 million sodium and 0.51 million aluminum nuclei collected by the Alpha Magnetic Spectrometer experiment on the International Space Station. We found that Na and Al, together with nitrogen (N), belong to a distinct cosmic ray group. In this group, we observe that, similar to the N flux, both the Na flux and Al flux are well described by the sums of a primary cosmic ray component (proportional to the silicon flux) and a secondary cosmic ray component (proportional to the fluorine flux). The fraction of the primary component increases with rigidity for the N, Na, and Al fluxes and becomes dominant at the highest rigidities. The Na/Si and Al/Si abundance ratios at the source, 0.036±0.003 for Na/Si and 0.103±0.004 for Al/Si, are determined independent of cosmic ray propagation.

Properties of Heavy Secondary Fluorine Cosmic Rays: Results from the Alpha Magnetic Spectrometer.

Precise knowledge of the charge and rigidity dependence of the secondary cosmic ray fluxes and the secondary-to-primary flux ratios is essential in the understanding of cosmic ray propagation. We report the properties of heavy secondary cosmic ray fluorine F in the rigidity R range 2.15 GV to 2.9 TV based on 0.29 million events collected by the Alpha Magnetic Spectrometer experiment on the International Space Station. The fluorine spectrum deviates from a single power law above 200 GV. The heavier secondary-to-primary F/Si flux ratio rigidity dependence is distinctly different from the lighter B/O (or B/C) rigidity dependence. In particular, above 10 GV, the F/Si/B/O ratio can be described by a power law R^{δ} with δ=0.052±0.007. This shows that the propagation properties of heavy cosmic rays, from F to Si, are different from those of light cosmic rays, from He to O, and that the secondary cosmic rays have two classes.

Properties of Iron Primary Cosmic Rays: Results from the Alpha Magnetic Spectrometer.

We report the observation of new properties of primary iron (Fe) cosmic rays in the rigidity range 2.65 GV to 3.0 TV with 0.62×10^{6} iron nuclei collected by the Alpha Magnetic Spectrometer experiment on the International Space Station. Above 80.5 GV the rigidity dependence of the cosmic ray Fe flux is identical to the rigidity dependence of the primary cosmic ray He, C, and O fluxes, with the Fe/O flux ratio being constant at 0.155±0.006. This shows that unexpectedly Fe and He, C, and O belong to the same class of primary cosmic rays which is different from the primary cosmic rays Ne, Mg, and Si class.

Periodicities in the Daily Proton Fluxes from 2011 to 2019 Measured by the Alpha Magnetic Spectrometer on the International Space Station from 1 to 100 GV.

We present the precision measurement of the daily proton fluxes in cosmic rays from May 20, 2011 to October 29, 2019 (a total of 2824 days or 114 Bartels rotations) in the rigidity interval from 1 to 100 GV based on 5.5×10^{9} protons collected with the Alpha Magnetic Spectrometer aboard the International Space Station. The proton fluxes exhibit variations on multiple timescales. From 2014 to 2018, we observed recurrent flux variations with a period of 27 days. Shorter periods of 9 days and 13.5 days are observed in 2016. The strength of all three periodicities changes with time and rigidity. The rigidity dependence of the 27-day periodicity is different from the rigidity dependences of 9-day and 13.5-day periods. Unexpectedly, the strength of 9-day and 13.5-day periodicities increases with increasing rigidities up to ∼10 GV and ∼20 GV, respectively. Then the strength of the periodicities decreases with increasing rigidity up to 100 GV.

Properties of Neon, Magnesium, and Silicon Primary Cosmic Rays Results from the Alpha Magnetic Spectrometer.

We report the observation of new properties of primary cosmic rays, neon (Ne), magnesium (Mg), and silicon (Si), measured in the rigidity range 2.15 GV to 3.0 TV with 1.8×10^{6} Ne, 2.2×10^{6} Mg, and 1.6×10^{6} Si nuclei collected by the Alpha Magnetic Spectrometer experiment on the International Space Station. The Ne and Mg spectra have identical rigidity dependence above 3.65 GV. The three spectra have identical rigidity dependence above 86.5 GV, deviate from a single power law above 200 GV, and harden in an identical way. Unexpectedly, above 86.5 GV the rigidity dependence of primary cosmic rays Ne, Mg, and Si spectra is different from the rigidity dependence of primary cosmic rays He, C, and O. This shows that the Ne, Mg, and Si and He, C, and O are two different classes of primary cosmic rays.

Resection of biliary mucinous cystic neoplasms of the liver: a prospective cohort series of 13 consecutive patients.

BACKGROUND: Biliary mucinous cystic neoplasms (BMCNs) are uncommon neoplastic septated intrahepatic cysts which are often incorrectly diagnosed and have the potential for malignant transformation. OBJECTIVE: To assess the outcome of surgical resection of BMCNs. METHOD: A prospective liver surgery database was used to identify patients who underwent surgery at Groote Schuur Hospital Complex for BMCN from 1999 to 2015. Demographic variables including age and gender were documented as well as detailed preoperative imaging, location and size, operative treatment, extent of resection, histology, postoperative complications and outcome. RESULTS: Thirteen female patients (median age 45 years) had surgery. Eleven were diagnosed by imaging for symptoms. Two were jaundiced. One cyst was found during an elective cholecystectomy. Five cysts were located centrally in the liver. Before referral three cysts were treated with percutaneous drainage and two were treated with operative deroofing. Six patients had anatomical liver resections and seven patients had non anatomical liver resections of which two needed ablation of residual cyst wall. One patient needed a biliary-enteric reconstruction to treat a fistula. Median operative time was 183 minutes (range: 130-375). No invasive carcinoma was found. There was no operative mortality. One surgical site infection and one intra-abdominal collection were treated. Two patients developed recurrent BMCN after 24 months. CONCLUSION: BMCNs should be considered in middle aged women who have well encapsulated multilocular liver cysts. Treatment of large central BMCNs adjacent to vascular and biliary structures may require technically complex liver resections and are best managed in a specialised hepato-pancreatico-biliary unit.

Distal malignant biliary obstruction: a prospective randomised trial comparing plastic and uncovered self-expanding metal stents in the palliation of symptomatic jaundice.

BACKGROUND: The aim of this study was to determine the safety and clinical effectiveness of 10Fr plastic biliary stents compared to uncovered self-expanding metal stents (SEMS) for palliative treatment of patients with inoperable extra-hepatic malignant biliary obstruction in a public hospital in South Africa. METHOD: From January 2009 to December 2013, 40 patients who were admitted to a tertiary academic centre because of distal malignant biliary obstruction were enrolled in a prospective randomized study. Patients were randomly assigned to receive an uncovered SEMS or a plastic stent deployed through the biliary stricture during endoscopic retrograde cholangiopancreatography (ERCP). RESULTS: Patient survival time in the two groups did not differ significantly (median: SEMS - 114 days; plastic - 107 days). Stent failure was more common in the plastic stent group (7/19 vs. 1/21). The results became significant after 6 months of follow-up. There was no significant difference between the two groups in the incidence of serious adverse events. CONCLUSION: SEMS had a longer duration of patency than plastic stents, which recommends their use in the palliative treatment of patients with biliary obstruction due to distal malignant biliary obstruction.

Distal malignant biliary obstruction: a prospective randomised trial comparing plastic and uncovered self-expanding metal stents in the palliation of symptomatic jaundice

Background: The aim of this study was to determine the safety and clinical effectiveness of 10Fr plastic biliary stents compared to uncovered self-expanding metal stents (SEMS) for palliative treatment of patients with inoperable extra-hepatic malignant biliary obstruction in a public hospital in South Africa.Methods: From January 2009 to December 2013, 40 patients who were admitted to a tertiary academic centre because of distal malignant biliary obstruction were enrolled in a prospective randomized study. Patients were randomly assigned to receive an uncovered SEMS or a plastic stent deployed through the biliary stricture during endoscopic retrograde cholangiopancreatography (ERCP).Results: Patient survival time in the two groups did not differ significantly (median: SEMS ­ 114 days; plastic ­ 107 days). Stent failure was more common in the plastic stent group (7/19 vs. 1/21). The results became significant after 6 months of follow-up. There was no significant difference between the two groups in the incidence of serious adverse events.Conclusions: SEMS had a longer duration of patency than plastic stents, which recommends their use in the palliative treatment of patients with biliary obstruction due to distal malignant biliary obstruction

Resection of biliary mucinous cystic neoplasms of the liver: a prospective cohort series of 13 consecutive patients

Background: Biliary mucinous cystic neoplasms (BMCNs) are uncommon neoplastic septated intrahepatic cysts which are often incorrectly diagnosed and have the potential for malignant transformation.Objectives:To assess the outcome of surgical resection of BMCNs.Methods:A prospective liver surgery database was used to identify patients who underwent surgery at Groote Schuur Hospital Complex for BMCN from 1999 to 2015. Demographic variables including age and gender were documented as well as detailed preoperative imaging, location and size, operative treatment, extent of resection, histology, postoperative complications and outcome.Results:Thirteen female patients (median age 45 years) had surgery. Eleven were diagnosed by imaging for symptoms. Two were jaundiced. One cyst was found during an elective cholecystectomy. Five cysts were located centrally in the liver. Before referral three cysts were treated with percutaneous drainage and two were treated with operative deroofing. Six patients had anatomical liver resections and seven patients had non anatomical liver resections of which two needed ablation of residual cyst wall. One patient needed a biliary-enteric reconstruction to treat a fistula. Median operative time was 183 minutes (range: 130­375). No invasive carcinoma was found. There was no operative mortality. One surgical site infection and one intra-abdominal collection were treated. Two patients developed recurrent BMCN after 24 months.Conclusion:BMCNs should be considered in middle aged women who have well encapsulated multilocular liver cysts. Treatment of large central BMCNs adjacent to vascular and biliary structures may require technically complex liver resections and are best managed in a specialised hepato-pancreatico-biliary unit

Resection of benign liver tumours: an analysis of 62 consecutive cases treated in an academic referral centre.

BACKGROUND: Benign tumours of the liver are increasingly diagnosed and constitute a substantial proportion of all hepatic tumours evaluated and resected at tertiary referral centres. This study assessed the safety and outcome after resection of benign liver tumours at a major referral centre. METHOD: All patients with symptomatic benign liver tumours who underwent resection were identified from a prospective departmental database of a total of 474 liver resections (LRs). Demographic data, operative management and morbidity and mortality using the Accordion classification were analysed. RESULTS: Sixty-two patients (56 women, 6 men, median age 45 years, range 17-82) underwent resection of symptomatic haemangiomata n=23 (37.1%), focal nodular hyperplasia n=19 (30.6%), biliary cystadenoma n=16 (25.8%) and hepatic adenomas n=4 (6.5%). A major resection was required in 25 patients, 14 patients had 4 segments resected, 11 had 3 segments and 37 patients had 2 or fewer segments resected. Median operating time was 169 minutes (range 80-410). Median blood loss was 300 ml (range 50-4500 ml) and an intra-operative blood transfusion was required in 6 patients. Median length of post-operative hospital stay was 7 days (range 4-32). Complications occurred in 11 patients (Accordion grades 1 n=1, 2 n=4, 3 n=1, 4 n=4, 6 n=1). Four patients required re-operation (bleeding n=2, bile leak n=1, small bowel obstruction n=1). An elderly patient died in hospital on day 16 following a postoperative cerebrovascular accident. CONCLUSION: Clinically relevant symptomatic benign liver tumours comprise a substantial proportion of LRs. Our data suggest that resections can be performed safely with minimal blood loss and transfusion requirements. We advocate selective resection according to established indications. Despite the low postoperative mortality rate, the risk of postoperative complications emphasizes the need for careful selection of patients for resection.

Incidence and management of postoperative bile leaks: A prospective cohort analysis of 467 liver resections.

BACKGROUND: Bile leaks from the parenchymal transection margin are a major cause of morbidity following major liver resections. The aim of this study was to benchmark the incidence and identify the risk factors for postoperative bile leakage after hepatic resection. PATIENTS AND METHODS: A prospective database of 467 consecutive liver resections performed by the University of Cape Town HPB surgical unit between January 1990 and January 2016 was analysed. The relationship of demographic, clinical and perioperative factors to the development of bile leakage was determined. Bile leak and postoperative complications severity were graded using the International Study Group of Liver Surgery and Accordion classifications. RESULTS: Overall morbidity was 24% (n = 112), with bile leaks occurring in 25 (5.4%) patients. Significantly more bile leaks occurred in patients who had major resections (≥ 3 segments) and longer total operative times (p < 0.05). There were 5 Grade A bile leaks which stopped spontaneously. Seventeen Grade B leaks required a combination of percutaneous drainage (n = 15), endoscopic biliary stenting (n = 8) and percutaneous transhepatic biliary drainage (n = 3). All 3 Grade C leaks required laparotomy for definitive drainage. Median hospital stay in the 442 patients without a bile leak was 8 days (IQR 1-98) compared with 12 days (IQR 6-30) for the 25 with bile leaks (p < 0.05) with no mortality. Major resections (≥ 3 segments) and total operative time (> 180mins) were significantly associated with bile leaks. CONCLUSION: The incidence of bile leakage was 5.4% and occurred after major liver resections with longer operative times and resulted in significantly extended hospitalisation. Most were effectively treated nonoperatively by percutaneous drainage of the collection and/or endoscopic or percutaneous biliary drainage without mortality.

Primary seromucinous cystadenocarcinoma of the mesentery.

A 72-year-old woman presented with a slow growing mass on the left side of the abdomen, which was found to originate from the mesentery of the descending colon. Histopathology revealed a seromucinous cystadenocarcinoma of the mesentery, a rare clinical entity occurring most often in females. There are only 20 cases reported in the literature. It is postulated that these tumours develop as a result of serous or mucinous metaplasia of pre-existing coelomic mesothelium. Surgical excision remains the mainstay of successful management.

Severe post-pancreatoduodenectomy haemorrhage: An analytical review based on 118 consecutive pancreatoduodenectomy patients in a South African Academic Hospital.

BACKGROUND: Bleeding after a major pancreatic resection, although uncommon, has serious implications and substantial mortality rates. AIM: To analyse our experience with severe post-pancreatoduodenectomy haemorrhage (PPH) over the last 7 years to establish the incidence, causes, intervention required and outcome. METHOD: All patients who underwent a pancreatoduodenectomy (PD) between January 2008 and December 2015 were identified from a prospectively maintained database. Data analysed included demographic information, operative details, anastomotic technique, histology, postoperative complications including pancreatic fistula and PPH, length of hospital stay, need for blood products and special investigations. Pancreatic fistula was classified according to the International Study Group of Pancreatic Surgery (ISGPS) classification. A modified ISGPS classification was used for PPH. RESULTS: One hundred and eighteen patients underwent PD during the study period of whom 6 (5.0%) died perioperatively. Twenty patients (16.9%) developed a pancreatic fistula and 11 patients (9.3%) had a severe PPH of whom one (9.1%) died. No patients had a severe bleed during the first 24 hours postoperatively. Four patients bled within the first 5 days and the remaining 7 after five days. Six patients bled from the gastroduodenal artery and were all preceded by a pancreatic fistula. Three of the 7 patients who bled late presented with extraluminal bleeding, 3 presented with intraluminal bleeding and 1 with a combination of both. Patients presenting in the first 5 days were all successfully managed either endoscopically or surgically. Five patients who presented beyond 5 days postoperatively were managed primarily with interventional angiography, either with coiling or deployment of a covered stent. Three patients who had radiological intervention developed a liver abscess or necrosis. CONCLUSION: Severe PPH is associated with substantial morbidity. Clinical factors including the onset of the bleeding, presentation with either extra and/or intraluminal haemorrhage, and the presence of a pancreatic fistula give an indication of the likely aetiology of the bleeding. A management algorithm based on these factors is presented.

Measurements of the neutron spectrum in transit to Mars on the Mars Science Laboratory.

The Mars Science Laboratory spacecraft, containing the Curiosity rover, was launched to Mars on 26 November 2011. Although designed for measuring the radiation on the surface of Mars, the Radiation Assessment Detector (RAD) measured the radiation environment inside the spacecraft during most of the 253-day, 560-million-kilometer cruise to Mars. An important factor for determining the biological impact of the radiation environment inside the spacecraft is the specific contribution of neutrons with their high biological effectiveness. We apply an inversion method (based on a maximum-likelihood estimation) to calculate the neutron and gamma spectra from the RAD neutral particle measurements. The measured neutron spectrum (12-436 MeV) translates into a radiation dose rate of 3.8±1.2 µGy/day and a dose equivalent of 19±5 µSv/day. Extrapolating the measured spectrum (0.1-1000 MeV), we find that the total neutron-induced dose rate is 6±2 µGy/day and the dose equivalent rate is 30±10 µSv/day. For a 360 day round-trip from Earth to Mars with comparable shielding, this translates into a neutron induced dose equivalent of about 11±4 mSv.