Stereotactic body radiation therapy in hepatocellular carcinoma: Optimal treatment strategies based on liver segmentation and functional hepatic reserve

AimTo discuss current dosage for stereotactic body radiation therapy (SBRT) in hepatocellular carcinoma (HCC) patients and suggest alternative treatment strategies according to liver segmentation as defined by the Couinaud classification.BackgroundSBRT is a safe and effective alternative treatment for HCC patients who are unable to undergo liver ablation/resection. However, the SBRT fractionation schemes and treatment planning strategies are not well established.Materials and methodsIn this article, the latest developments and key findings from research studies exploring the efficacy of SBRT fractionation schemes for treatment of HCC are reviewed. Patients’ characteristics, fractionation schemes, treatment outcomes and toxicities were compiled. Special attention was focused on SBRT fractionation approaches that take into consideration liver segmentation according to the Couinaud classification and functional hepatic reserve based on Child–Pugh (CP) liver cirrhosis classification.ResultsThe most common SBRT fractionation schemes for HCC were 3 × 10–20 Gy, 4–6 × 8–10 Gy, and 10 × 5–5.5 Gy. Based on previous SBRT studies, and in consideration of tumor size and CP classification, we proposed 3 × 15–25 Gy for patients with tumor size <3 cm and adequate liver reserve (CP-A score 5), 5 × 10–12 Gy for patients with tumor sizes between 3 and 5 cm or inadequate liver reserve (CP-A score 6), and 10 × 5–5.5 Gy for patients with tumor size >5 cm or CP-B score.ConclusionsTreatment schemes in SBRT for HCC vary according to liver segmentation and functional hepatic reserve. Further prospective studies may be necessary to identify the optimal dose of SBRT for HCC.     

Use of a second-dose calculation algorithm to check dosimetric parameters for the dose distribution of a first-dose calculation algorithm for lung SBRT plans

PurposeTo verify lung stereotactic body radiotherapy (SBRT) plans using a secondary treatment planning system (TPS) as an independent method of verification and to define tolerance levels (TLs) in lung SBRT between the primary and secondary TPSs.MethodsA total of 147 lung SBRT plans calculated using X-ray voxel Monte Carlo (XVMC) were exported from iPlan to Eclipse in DICOM format. Dose distributions were recalculated using the Acuros XB (AXB) and the anisotropic analytical algorithm (AAA), while maintaining monitor units (MUs) and the beam arrangement. Dose to isocenter and dose-volumetric parameters, such as D₂, D₅₀, D₉₅ and D₉₈, were evaluated for each patient. The TLs of all parameters between XVMC and AXB (TL_AXB) and between XVMC and AAA (TL_AAA) were calculated as the mean ± 1.96 standard deviations.ResultsAXB values agreed with XVMC values within 3.5% for all dosimetric parameters in all patients. By contrast, AAA sometimes calculated a 10% higher dose in PTV D₉₅ and D₉₈ than XVMC. The TL_AXB and TL_AAA of the dose to isocenter were −0.3 ± 1.4% and 0.6 ± 2.9%, respectively. Those of D₉₅ were 1.3 ± 1.8% and 1.7 ± 3.6%, respectively.ConclusionsThis study quantitatively demonstrated that the dosimetric performance of AXB is almost equal to that of XVMC, compared with that of AAA. Therefore, AXB is a more appropriate algorithm for an independent verification method for XVMC.     

Translational and rotational localization errors in cone-beam CT based image-guided lung stereotactic radiotherapy

PurposeAccurate localization is crucial in delivering safe and effective stereotactic body radiation therapy (SBRT). The aim of this study was to analyse the accuracy of image-guidance using the cone-beam computed tomography (CBCT) of the VERO system in 57 patients treated for lung SBRT and to calculate the treatment margins.Materials and methodsThe internal target volume (ITV) was obtained by contouring the tumor on maximum and mean intensity projection CT images reconstructed from a respiration correlated 4D-CT. Translational and rotational tumor localization errors were identified by comparing the manual registration of the ITV to the motion-blurred tumor on the CBCT and they were corrected by means of the robotic couch and the ring rotation. A verification CBCT was acquired after correction in order to evaluate residual errors.ResultsThe mean 3D vector at initial set-up was 6.6 ± 2.3 mm, which was significantly reduced to 1.6 ± 0.8 mm after 6D automatic correction. 94% of the rotational errors were within 3°. The PTV margins used to compensate for residual tumor localization errors were 3.1, 3.5 and 3.3 mm in the LR, SI and AP directions, respectively.ConclusionsOn-line image guidance with the ITV–CBCT matching technique and automatic 6D correction of the VERO system allowed a very accurate tumor localization in lung SBRT.     

Variation of the prescription dose using the analytical anisotropic algorithm in lung stereotactic body radiation therapy

PurposeThe aim of the present investigation was to evaluate the dosimetric variation regarding the analytical anisotropic algorithm (AAA) relative to other algorithms in lung stereotactic body radiation therapy (SBRT). We conducted a multi-institutional study involving six institutions using a secondary check program and compared the AAA to the Acuros XB (AXB) in two institutions.MethodsAll lung SBRT plans (128 patients) were generated using the AAA, pencil beam convolution with the Batho (PBC-B) and adaptive convolve (AC). All institutions used the same secondary check program (simple MU analysis [SMU]) implemented by a Clarkson-based dose calculation algorithm. Measurement was performed in a heterogeneous phantom to compare doses using the three different algorithms and the SMU for the measurements. A retrospective analysis was performed to compute the confidence limit (CL; mean ± 2SD) for the dose deviation between the AAA, PBC, AC and SMU. The variations between the AAA and AXB were evaluated in two institutions, then the CL was acquired.ResultsIn comparing the measurements, the AAA showed the largest systematic dose error (3%). In calculation comparisons, the CLs of the dose deviation were 8.7 ± 9.9% (AAA), 4.2 ± 3.9% (PBC-B) and 5.7 ± 4.9% (AC). The CLs of the dose deviation between the AXB and the AAA were 1.8 ± 1.5% and −0.1 ± 4.4%, respectively, in the two institutions.ConclusionsThe CL of the AAA showed much larger variation than the other algorithms. Relative to the AXB, larger systematic and random deviations still appeared. Thus, care should be taken in the use of AAA for lung SBRT.     

Problème diagnostique posé par une lésion hépatique hypermétabolique en TEP à la fluorocholine (18F) : à propos d’un cas

IntroductionWe report a case of atypical fluorocholine (18F) PET/CT hypermetabolic hepatic lesion discovered during the staging of a prostate carcinoma.Case reportBecause of elevated PSA serum level, the patient had prostate biopsies which elicited an adenocarcinoma with a Gleason score of 8 (4 + 4). Pelvic MRI did not display any extracapsular disease extension. The PET/CT scan demonstrated a prostatic focal uptake and a liver increased uptake area matching with a segment VII hepatic nodule measuring 25 mm within a fatty liver, which was hypometabolic on the PET scan and hypodense on the CT scan. The liver ultrasound study reported the lesion as a focal spared area of healthy liver tissue within steatosis, whereas MRI diagnostic conclusion was inflammatory hepatocellular adenoma. When asking the patient, it appeared that the hepatic nodule had been known for 7 years, its size was unchanged, and, from previous radiologic imaging, it had been considered as an adenoma. However, there was no histological proof.DiscussionIn the interpretation of the PET/CT scan findings, we excluded a hepatocellular carcinoma and a prostate metastasis due to the long period of time during which the nodule had been followed up without significant change. We thought that focal nodular hyperplasia, which is fluorocholine avid, was the most likely diagnosis, knowing that hepatocellular adenomas, including the inflammatory type, have not been reported to display increased fluorocholine uptake. We noticed that the patient's fatty liver uptake was low, which could have accounted for a falsely increased uptake by the nodule. But, similarly to other authors, we could not find any relationship between CT density and fluorocholine uptake.ConclusionThis case shows a discrepancy between the radiologic and nuclear medicine findings. However, this hepatic nodule is likely to be benign because of the lesion characteristics and the patient medical history.     

Local control rates in stereotactic body radiotherapy (SBRT) of lung metastases associated with the biologically effective dose

AimTo evaluate dose differences in lung metastases treated with stereotactic body radiotherapy (SBRT), and the correlation with local control, regarding the dose algorithm, target volume and tissue density.BackgroundSeveral studies showed excellent local control rates in SBRT for lung metastases, with different fractionation schemes depending on the tumour location or size. These results depend on the dose distributions received by the lesions in terms of the tissue heterogeneity corrections performed by the dose algorithms.Materials and methodsForty-seven lung metastases treated with SBRT, using intrafraction control and respiratory gating with internal fiducial markers as surrogates (ExacTrac, BrainLAB AG), were calculated using Pencil Beam (PB) and Monte Carlo (MC) (iPlan, BrainLAB AG).Dose differences between both algorithms were obtained for the dose received by 99% (D_99%) and 50% (D_50%) of the planning treatment volume (PTV). The biologically effective dose delivered to 99% (BED_99%) and 50% (BED_50%) of the PTV were estimated from the MC results. Local control was evaluated after 24 months of median follow-up (range: 3–52 months).ResultsThe greatest variations (40.0% in ΔD_99% and 38.4% in ΔD_50%) were found for the lower volume and density cases. The BED_99% and BED_50% were strongly correlated with observed local control rates: 100% and 61.5% for BED_99% > 85 Gy and <85 Gy (p < 0.0001), respectively, and 100% and 58.3% for BED_50% > 100 Gy and <100 Gy (p < 0.0001), respectively.ConclusionsLung metastases treated with SBRT, with delivered BED_99% > 85 Gy and BED_50% > 100 Gy, present better local control rates than those treated with lower BED values (p = 0.001).     

The relationship between ethnicity,social deprivation and late presentation of colorectal cancer

IntroductionTumour staging at time of presentation is an important factor in determining survival in colorectal cancer. The aim of this paper is to investigate the relationship between ethnicity and deprivation in late (Stage IV) presentation of colorectal cancer.MethodsData from the Thames Cancer Registry comprising 77,057 colorectal cancer patients between the years 2000 and 2012 were analysed.ResultsA total of 17,348 patients were identified with complete data, of which 53.9% were male. Patients from a Black Afro/Caribbean background were diagnosed with CRC at a much younger age than the White British group (median age 67 compared with 72, p < 0.001). In multiple regression, ethnicity, deprivation and age were positive predictors of presenting with advanced tumour stage at time of diagnosis. Black patients were more likely to present with Stage IV tumours than white patients (OR 1.37, 95% CI 1.18–1.59, p < 0.001). Social deprivation was also a predictor of Stage IV cancer presentation, with the most deprived group (Quintile 5) 1.26 times more likely to be diagnosed with Stage IV cancer compared with the most affluent group (CI 1.13–1.40, p < 0.001). Sub-group analyses demonstrated that Black & Affluent patients were still at greater risk of Stage IV CRC than their White & Affluent counterparts (OR 1.24, 95% CI 1.11–1.45, p = 0.023). Patients with rectal cancer were less likely to present with Stage IV CRC (OR 0.66, 95% CI 0.61–0.71, p < 0.001).ConclusionRacial and age related disparities exist in tumour presentation in the United Kingdom. Patients from black and socially deprived backgrounds as well as the elderly are more likely to present with advanced tumours at time of diagnosis.     

Impacto asistencial tras la introducción de la ecografía tiroidea en una unidad monográfica de atención al nódulo tiroideo

IntroductionWorldwide incidence of thyroid cancer has increased in recent decades.ObjectiveTo provide evidence of the diagnostic and care efficiency of a monographic thyroid nodule clinic integrating clinical examination, ultrasound examination, and cytology with on site evaluation.Patients and methodsPatients attending the monographic thyroid nodule clinic from January 2004 to June 2010. Two periods may be distinguished based on availability of ultrasound equipment at the time of the visit: a first period (P1: 01/2004-09/2007) where no ultrasound equipment was available at the clinic and FNA by palpation was performed, and a second period (P2: 10/2007-06/2010) where this equipment was available and ultrasound-guided FNA was performed.ResultsA total of 1036 patients [P1: 537 (52%), P2: 499 (48%)] were seen and enrolled.Diagnostic efficiency (P1 vs P2): 143 vs 181 patients were seen annually, p < 0.001; FNA number/nodule: 1.68 vs 1.17, p < 0.001; percent FNAs with inadequate material: 26% vs 5.3%, p < 0.001; mean (SD) nodule size: 23.6 (12.4) vs 21.7 (11.7) mm, p 0.040; proportion of nodules examined less than 10 mm in size: 9.9% vs 13.7%, p 0.030.Care efficiency: mean time (range) from the first visit to surgery indication: 332 (0-2177) vs 108 (0-596) days, p < 0.001; proportion of patients referred for surgery due to suspect cytology/other reasons: 1.06 vs 2.21, p < 0.001; and operated benign neoplasm/pathology: 0.47 vs 0.93, p = 0.002.ConclusionA monographic thyroid nodule clinic integrating clinical examination, ultrasound, and cytology evaluated on site increases diagnostic and care efficiency in patients with thyroid nodules.     

Diagnostic de l’embolie pulmonaire chez la femme enceinte : apport de la scintigraphie. Étude rétrospective à propos de 116 cas

IntroductionPulmonary embolism during pregnancy is a leading cause of maternal mortality. The aim of our study was to evaluate pregnant women with suspected pulmonary embolism prevalence of lesions on the lung perfusion as well as the relationship between the parenchymal lesions and various clinical factors and biological risk.MethodsThis is a retrospective study of 116 pregnant patients referred for suspected pulmonary embolism. The median age was 30 years, ranging from 15 to 47 years and the median gestational term was 31 weeks with a range of 12 to 40 weeks. Suspicion of pulmonary embolism was established with the presence of clinical signs (dyspnea, chest pain and palpitations). No patient had received a chest radiograph. The patients underwent planar perfusion scintigraphy with injected activity of 40 to 50 MBq of macroaggregates of human albumin (MAA) labeled with 99mTc. The scintigraphic results were classified according to the PIOPED criteria, depending on the likelihood of EP. The scans with low or intermediate probability were included in the same group, that of indeterminate results.ResultsThe scan was positive (with high probability) in 16 patients (13.8%), normal in 78 patients (67.2%) and classified as inconclusive in 22 patients (18.9%). In 16 patients with a positive scan, the lesions were interested the left lung in 10 cases (62.5%), the right lung in 1 case (6.25%) and were bilateral in 5 cases (31.25%).ConclusionsIn cases of suspected pulmonary embolism in a pregnant woman, the choice of imaging technique depends on both its diagnostic value and also its adverse effects. Lung scintigraphy is the examination to be carried out first in pregnant women with a chest radiograph. In others, it is that angiography should be performed as first line.     

Biochemical relapse free survival rate in patients with prostate cancer treated with external radiotherapy: outcomes obtained at the CMN Siglo XXI Hospital de Oncología,CMN 20 de Noviembre and Hospital General de México of the México City

AimBiochemical relapse-free survival (bRFS) rate is determined by a cohort of Mexican patients (n = 595) with prostate cancer who received treatment with external radiotherapy.BackgroundPatients with prostate cancer were collected from CMN Siglo XXI (IMSS), CMN 20 de Noviembre (ISSSTE), and Hospital General de México (HGM). For the IMSS, 173 patients that are treated with three-dimensional conformal radiation therapy (3D-CRT) and 250 with SBRT, for the ISSSTE 57 patients are treated with 3D-CRT and on the HGM 115 patients are managed with intensity modulated radiation therapy (IMRT). The percentage of patients by risk group is: low 11.1%, intermediate 35.1% and high 53.8%. The average follow-up is 39 months, and the Phoenix criterion was used to determine the bRFS.Materials and methodsThe Kaplan–Meier technique for the construction of the survival curves and, the Cox proportional hazards to model the cofactors.Results(a) The bRFS rates obtained are 95.9% for the SBRT (7 Gy fx, IMSS), 94.6% for the 3D-CRT (1.8 Gy fx, IMSS), 91.3% to the 3D-CRT (2.65 Gy fx, IMSS), 89.1% for the SBRT (7.25 Gy fx, IMSS), 88.7% for the IMRT (1.8 Gy fx, HGM) %, and 87.7% for the 3D-CRT (1.8 Gy fx, ISSSTE). (b) There is no statistically significant difference in the bRFS rates by fractionation scheme, c) Although the numerical difference in the bRFS rate per risk group is 95.5%, 93.8% and 89.1% for low, intermediate and high risk, respectively, these are not statistically significant.ConclusionsThe RT techniques for the treatment of PCa are statistically equivalent with respect to the bRFS rate. This paper confirms that the bRFS rates of Mexican PCa patients who were treated with conventional vs. hypofractionated schemes do not differ significantly.     

Asynchronisme cardiaque chez le sujet à QRS fin. Étude par échocardiographie Doppler tissulaire

ObjectiveTo assess the prevalence of different types of cardiac dyssynchrony by pulsed Doppler ultrasound and Doppler tissue in patients with narrow QRS with or without left ventricular systolic dysfunction.MethodologyProspective, cross-sectional survey at the Institute of Cardiology of Abidjan, from January to April 2012, in subjects with narrow QRS. Group 1: patients with dilated cardiomyopathy with severe left ventricular dysfunction (left ventricular end diastolic diameter greater than 60 mm and/or 30 mm/m² and ejection fraction less than 35% NYHA stage IV). Group 2: normal subjects with normal echocardiography. All patients underwent an evaluation including tissue Doppler search for different types of dyssynchrony (atrioventricular, interventricular and left intraventricular).ResultsPatients in group 1 were significantly older (51.5 ± 15.8 vs. 35.8 ± 7.8, P = 0.03), with larger left ventricular diameters and significantly higher pulmonary systolic pressure. The prevalence of different types of dyssynchrony in group 1 were: atrioventricular dyssynchrony 43.7%, interventricular dyssynchrony 37.5%, left ventricular dyssynchrony 65.6%. Group 2: atrioventricular dyssynchrony 0%, interventricular dyssynchrony 0%, left ventricular dyssynchrony 35%.ConclusionA large proportion of patients with left ventricular systolic dysfunction and narrow QRS have cardiac dyssynchrony and left ventricular dyssynchrony can be found in healthy patients. This raises the problem of the specificity of Doppler ultrasound criteria using cardiac tissue Doppler to assess cardiac dyssynchrony.     

Conduction velocity of the human phrenic nerve in the neck

PurposeTo measure phrenic nerve conduction velocity in the neck in humans.ScopeWe studied 15 healthy subjects (9 men, 32.4 ± 6.7). We performed bipolar electrical phrenic stimulation in the neck, from a distal and a proximal stimulation site, and recorded diaphragm electromyographic responses on the surface of the chest. The ratio of the between-site distance to the latency difference provided phrenic velocities. Ulnar motor velocity was assessed similarly. In addition, five homogeneous patients with Charcot-Marie-Tooth disease type 1A (CMT1A) were studied for validation purposes. We obtained diaphragmatic responses from the two stimulation sites in all cases. The distal latencies (anterior axillary line recording) were 6.51 ± 0.63 ms (right) and 6.13 ± 0.64 ms (left). The minimal between site distance was 39 mm. Phrenic motor velocity was 55.2 ± 6.3 m s^?1 (right) and 56.3 ± 7.2 m s^?1 (left). In CMT1A, phrenic velocities were 17.1 ± 8.1 m s^?1 (from 7 to 32 m s^?1) and were similar to ulnar and median velocities.ConclusionsPhrenic nerve velocities can be estimated in humans and compare with upper limb motor conduction velocities. This should refine the investigation of phrenic function in peripheral neuropathies.     

Transrectal implantation and stability of gold markers in prostate bed for salvage radiotherapy of macroscopic recurrences

Background and purposeThe objective of the study was to verify the stability of gold markers in the prostatic bed (PB) during salvage radiotherapy.Material and methodsSeven patients, diagnosed with a macroscopic nodule visible on MRI, underwent targeted MRI-guided biopsies. Three gold markers were implanted into the PB close to the relapsing nodule for CT/MRI fusion. A dose of 60 Gy was delivered using IMRT to the PB followed by a dose escalation up to 72 Gy to the macroscopic nodule. Daily anterior and left-lateral kV-images were acquired for repositioning. The coordinates of the center of each marker were measured on the two kV-images. The distance variations (Dvar) of the markers in the first session and the subsequent ones were compared.ResultsNo marker was lost during treatment. The average distance between markers was 7.8 mm. The average Dvar was 0.8 mm, in absolute value. A total of 380/528 (72%) Dvar were ⩽1 mm. A Dvar greater than 2 mm was observed in 5.7% of measurements, with a maximum value of 4.8 mm.ConclusionsDespite the absence of the prostate, the implantation of gold markers in the PB remains feasible, with Dvar often less than 2 mm, and could be used to develop new approaches of salvage focal radiotherapy on the macroscopic relapse after prostatectomy.     

Evaluation of the target dose coverage of stereotactic body radiotherapy for lung cancer using helical tomotherapy: A dynamic phantom study

AimTo evaluate the target dose coverage for lung stereotactic body radiotherapy (SBRT) using helical tomotherapy (HT) with the internal tumor volume (ITV) margin settings adjusted according to the degree of tumor motion.BackgroundLung SBRT with HT may cause a dosimetric error when the target motion is large.Materials and methodsTwo lung SBRT plans were created using a tomotherapy planning station. Using these original plans, five plans with different ITV margins (4.0–20.0 mm for superior-inferior [SI] dimension) were generated. To evaluate the effects of respiratory motion on HT, an original dynamic motion phantom was developed. The respiratory wave of a healthy volunteer was used for dynamic motion as the typical tumor respiratory motion. Five patterns of motion amplitude that corresponded to five ITV margin sizes and three breathing cycles of 7, 14, and 28 breaths per minute were used. We evaluated the target dose change between a static delivery and a dynamic delivery with each motion pattern.ResultsThe target dose difference increased as the tumor size decreased and as the tumor motion increased. Although a target dose difference of <5 % was observed at ≤10 mm of tumor motion for each condition, a maximum difference of -9.94 % ± 7.10 % was observed in cases of small tumors with 20 mm of tumor motion under slow respiration.ConclusionsMinimizing respiratory movement is recommended as much as possible for lung SBRT with HT, especially for cases involving small tumors.     

In silico comparison of photons versus carbon ions in single fraction therapy of lung cancer

PurposeStereotactic body image guided radiation therapy (SBRT) shows good results for lung cancer treatment. Better normal tissue sparing might be achieved with scanned carbon ion therapy (PT). Therefore an in silico trial was conducted to find potential advantages of and patients suited for PT.MethodsFor 19 patients treated with SBRT, PT plans were calculated on 4D-CTs with simulated breathing motion. Prescribed single fraction dose was 24 Gy and OAR constraints used for photon planning were respected. Motion was mitigated by rescanning and range-adapted ITVs. Doses were compared to the original SBRT plans.ResultsCTV coverage was the same in SBRT and PT. The field-specific PTV including range margins for PT was 1.5 (median, 25–75% 1.3–2.1) times larger than for SBRT. Nevertheless, maximum point dose and mean dose in OARs were higher in SBRT by 2.8 (1.6–3.7) Gy and 0.7 (0.3–1.6) Gy, respectively. Patients with a CTV >2.5 cc or with multiple lung lesions showed larger differences in OAR doses in favor of PT.ConclusionsPatients receive less dose in critical OARs such as heart, spinal cord, esophagus, trachea and aorta with PT, while maintaining the same target coverage. Patients with multiple or larger lesions are particularly suited for PT.     

Variable angle stereo imaging for rapid patient position correction in an in-house real-time position monitoring system

PurposeTo develop and validate a variable angle stereo image based position correction methodology in an X-ray based in-house online position monitoring system.Materials and methodsA stereo imaging module that enables 3D position determination and couch correction of the patient based on images acquired at any arbitrary angle and arbitrary angular separation was developed and incorporated to the in-house SeedTracker real-time position monitoring system. The accuracy of the developed system was studied by imaging an anthropomorphic phantom implanted with radiopaque markers set to known offset positions from its reference position in an Elekta linear accelerator (LA) and associated XVI imaging system. The accuracy of the system was further validated using CBCT data set from 10 prostate SBRT patients. The time gains achieved with the stereo image based position correction was compared with the manual matching of seed positions in Digitally Reconstructed Radiographs (DRRs) and kV images in the Mosaiq record and verify system.ResultsBased on phantom and patient CBCT dataset study stereo imaging module implemented in the SeedTracker shown to have an accuracy of 0.1(σ = 0.5) mm in detecting the 3D position offset. The time comparison study showed that stereo image based methodology implemented in SeedTracker was a minimum of 80(4) s faster than the manual method implemented in Mosaiq R&V system with a maximum time saving of 146(6) s.ConclusionThe variable angle stereo image based position correction method was shown to be accurate and faster than the standard manual DRR–kV image based correction approach, leading to more efficient treatment.     

The effect of deep hypothermia on the human pulmonary circulation

ObjectiveAcute rises in pulmonary artery pressures following complex cardiac surgery are associated with high morbidity and mortality. We hypothesised that periods of deep hypothermia predispose to elevated pulmonary pressures upon rewarming. We investigated the effect of this hypothermic preconditioning on isolated human pulmonary arteries and isolated perfused lungs.MethodsIsometric tension was measured in human pulmonary artery rings (n=24). We assessed the constriction and dilation of these arteries at 37 °C and 17 °C. Isolated perfused human lung models consisted of lobes ventilated via a bronchial cannula and perfused with Krebs via a pulmonary artery cannula. Bronchial and pulmonary artery pressures were recorded. We investigated the effect of temperature using a heat exchanger.ResultsRewarming from 17 °C to 37 °C caused a 1.3 fold increase in resting tension (p<0.05). Arteries constricted 8.6 times greater to 30 nM KCl, constricted 17 times greater to 1 nM Endothelin-1 and dilated 30.3 times greater to 100 μM SNP at 37 °C than at 17 °C (p<0.005). No difference was observed in the responses of arteries originally maintained at 37 °C compared to those arteries maintained at 17 °C and rewarmed to 37 °C. Hypothermia blunted the increase in pulmonary artery pressures to stimulants such as potassium chloride as well as to H-R but did not precondition arteries to higher pulmonary artery pressures upon re-warming.ConclusionsDeep hypothermia reduces the responsiveness of human pulmonary arteries but does not, however, precondition an exaggerated response to vasoactive agents upon re-warming.     

Is the lack of respiratory gating prejudicial for left breast TomoDirect treatments?

Background and purposeTomoDirect (TD) can only operate in free-breathing. The purpose of this study is to compare TD with breath-hold 3D conformal radiotherapy (3DCRT) and intensity modulated radiotherapy (IMRT) techniques for left breast treatments, and to determine if the lack of respiratory gating is a handicap for cardiac sparing.Materials and methods15 patients treated for left breast had two computed tomography simulation, in free breathing (FB) and in deep-inspiration breath-hold (DIBH). Four treatments were planned: TD-FB, 3DCRT-FB, 3DCRT-DIBH and IMRT-DIBH. Dose to PTV, heart, lungs, right breast and patient were compared.ResultsA slightly lower cardiac mean dose is found for 3DCRT-DIBH than for TD-FB group (1.99 Gy Vs 2.89 Gy, p = 0.0462), while no statistical difference is found for heart V₂₀. TD-FB plans show the best PTV dose homogeneity (0.053, p < 0.001) and the lowest left lung mean dose (5.16 Gy, p < 0.001). No major differences are found for the other organs.ConclusionsTomoDirect and breath-hold 3DCRT are complementary techniques for left breast treatments: for a minority of patients, respiratory gating is mandatory to lower cardiac dose; for the remaining majority of patients, TomoDirect achieves better PTV homogeneity and reduced left lung dose, with cardiac dose equivalent to 3DCRT-DIBH.     

The importance of image guided radiotherapy in small cell lung cancer: Case report and review of literature

AimDescribe the anatomical changes and tumor displacement due to a rapid response of a patient’s small cell lung cancer (SCLC) during definitive chemoradiotherapy (CRT).BackgroundThe treatment for SCLC is based on CRT. If interfractional changes during RT are incorrectly assessed they might compromise adequate coverage of the tumor or increase dose to organs at risk. Image guided RT with cone-beam computed tomography (CBCT) allows to identify daily treatment variations.Material and methodsDescribe a SCLC case with rapid changes in size, shape and location of the primary tumor during RT.Case reportA 62-year-old woman was diagnosed with SCLC with complete obstruction of the anterior and lingular bronchi and incomplete left thorax expansion due to a 12 × 15 cm mass. During CRT (45 Gy in 1.5 Gy per fraction, twice daily) the patient presented rapid tumor response, leading to resolution of bronchi obstruction and hemithorax expansion. Tumor shifted up to 4 cm from its original position. The identification of variations led to two new simulations and planning in a 3-week treatment course.ConclusionsThe complete radiological response was possible due to systematic monitoring of the tumor during CRT. We recommend frequent on-site image verification. Daily CBCT should be considered with pretreatment tumor obstruction, pleural effusion, atelectasis, large volumes or radiosensitive histology that might resolve early and rapidly and could lead to a miss of the tumor or increased toxicity. Further research should be made in replanning effect in coverage of microscopic disease since it increases uncertainty in this scenario.