Dose-escalated simultaneous integrated-boost treatment of prostate cancer patients via helical tomotherapy

Purpose

The goal of this work was to assess the feasibility of moderately hypofractionated simultaneous integrated-boost intensity-modulated radiotherapy (SIB-IMRT) with helical tomotherapy in patients with localized prostate cancer regarding acute side effects and dose–volume histogram data (DVH data).

Methods

Acute side effects and DVH data were evaluated of the first 40 intermediate risk prostate cancer patients treated with a definitive daily image-guided SIB-IMRT protocol via helical tomotherapy in our department. The planning target volume including the prostate and the base of the seminal vesicles with safety margins was treated with 70?Gy in 35 fractions. The boost volume containing the prostate and 3?mm safety margins (5?mm craniocaudal) was treated as SIB to a total dose of 76?Gy (2.17?Gy per fraction). Planning constraints for the anterior rectal wall were set in order not to exceed the dose of 76?Gy prescribed to the boost volume. Acute toxicity was evaluated prospectively using a modified CTCAE (Common Terminology Criteria for Adverse Events) score.

Results

SIB-IMRT allowed good rectal sparing, although the full boost dose was permitted to the anterior rectal wall. Median rectum dose was 38?Gy in all patients and the median volumes receiving at least 65?Gy (V65), 70?Gy (V70), and 75?Gy (V75) were 13.5%, 9%, and 3%, respectively. No grade?4 toxicity was observed. Acute grade?3 toxicity was observed in 20% of patients involving nocturia only. Grade?2 acute intestinal and urological side effects occurred in 25% and 57.5%, respectively. No correlation was found between acute toxicity and the DVH data.

Conclusion

This institutional SIB-IMRT protocol using daily image guidance as a precondition for smaller safety margins allows dose escalation to the prostate without increasing acute toxicity.     

Lhermitte sign and myelopathy after irradiation of the cervical spinal cord in radiotherapy treatment of head and neck cancer

Background and purpose

The goal of this work was to examine toxicity and risk factors after irradiation of the cervical spinal cord.

Patients and methods

A total of 437?patients irradiated for a laryngeal and oropharyngeal carcinoma were eligible (median follow-up 27?months). Spinal cord contouring was defined differently over time as anatomically defined spinal cord area (SCA) and the spinal cord on CT (SC) with a margin of 3 or 5?mm (SCP3/SCP5).

Results

None developed chronic progressive radiation myelopathy (CPRM) (maximum spinal dose 21.8?C69?Gy); 3.9% (17/437) developed a Lhermitte sign (LS) with a median duration of 6?months (range 1?C30?months) and was reversible in all patients. Risk factors for developing LS were younger age (52 vs. 61?years, p?3 and 7.9?cm³ for patients with and without LS, respectively.

Conclusion

LS is more frequently observed in younger patients and in patients treated with accelerated radiotherapy. A dose?Cvolume relationship was seen for V45 in the case of SCA. For higher doses, no clear dose?Cvolume relationships were observed.     

Moderate hypofractionation and simultaneous integrated boost with volumetric modulated arc therapy (RapidArc) for prostate cancer

Purpose

In the present study, the acute toxicity profiles for prostate patients treated with simultaneous integrated boost (SIB) with volumetric modulated arcs in a hypofractionated regime are reported.

Patients and methods

A total of 70?patients treated with RapidArc between May 2010 and September 2011 were retrospectively evaluated. Patients were stratified into low (36%), intermediate (49%), and high-risk (16%) groups. Target volumes (expanded to define the planning volumes (PTV)) were clinical target volume (CTV) 1: prostate; CTV2: CTV1 + seminal vesicles; CTV3: CTV2 + pelvic nodes. Low-risk patients received 71.4?Gy to PTV1; intermediate-risk 74.2?Gy to PTV1 and 61.6 or 65.5?Gy to PTV2; high-risk 74.2?Gy to PTV1, 61.6 or 65.5?Gy to PTV2, and 51.8?Gy to PTV3. All treatments were in 28?fractions. The median follow-up was 11?months (range 3.5–23?months). The acute rectal, gastrointestinal (GI) and genitourinary (GU) toxicities were scored according to EORTC/RTOG scales.

Results

Acute toxicities were recorded for the GU [G0?=?31/70 (44%), G1?=?22/70 (31%); G2?=?16/70 (23%); G3?=?1/70 (1%)], the rectum [G0?=?46/70 (66%); G1?=?12/70 (17%); G2?=?12/70 (17%); no G3], and the GI [G0?=?54/69 (77%); G1?=?11/69 (16%); G2?=?4/69 (6%); no G3]. Median time to rectal, GU, and GI toxicities were 27, 30, and 33 days, respectively. Only the GI toxicity correlated with stage and pelvic irradiation. Univariate analysis presented significant correlations between GI toxicity and intestinal irradiation (V_50?Gy and V_60?Gy). In the multivariate analysis, the only significant dosimetric variable was V_50?Gy for the intestinal cavity.

Conclusion

Moderate hypofractionation with SIB and RapidArc was shown to be safe, with acceptable acute toxicity. Longer follow-up is needed to assess late toxicity and clinical outcome.     

Reduction of rectal doses by removal of gas in the rectum during vaginal cuff brachytherapy

Objective

The goal of this work was to evaluate whether the volume reduction related to removal of gas in the rectum could be translated in lower doses to organs at risk (OAR) during vaginal cuff brachytherapy (VBT).

Material and methods

Fourteen pairs of brachytherapy planning CT scans derived from 11 patients were re-segmented and re-planned using the same parameters. The only difference between pairs of CTs was the presence or lack of gas in the rectum. The first CT showed the basal status and the second was carried out after gas removal with a tube. A set of values derived from bladder and rectum dose–volume histograms (DVH) and dose–surface histograms (DSH) were extracted. Moreover the cylinder position related to the patient craniocaudal axis was recorded.

Results

Rectum volume decreased significantly from 77.8?±?45 to 55.43?±?17.6 ml (p?=?0.0052) after gas removal. Such volume diminution represented a significant reduction on all rectal DVH parameters analyzed except D_25?% and D_50?%. DSH parameter results were similar to previous ones. A nonsignificant increase of the bladder volume was observed and was associated with an increase of the DVH metrics analyzed.

Conclusion

Removal of gas pockets is a simple and inexpensive maneuver that decreases rectal dose parameters on VBT, which can be translated as a better therapeutic ratio. It also suggests that other actions directed to empty the rectum could have a similar effect.     

Practically acquired and modified cone-beam computed tomography images for accurate dose calculation in head and neck cancer

Background

On-line cone-beam computed tomography (CBCT) may be used to reconstruct the dose for geometric changes of patients and tumors during radiotherapy course. This study is to establish a practical method to modify the CBCT for accurate dose calculation in head and neck cancer.

Patients and Methods

Fan-beam CT (FBCT) and Elekta??s CBCT were used to acquire images. The CT numbers for different materials on CBCT were mathematically modified to match them with FBCT. Three phantoms were scanned by FBCT and CBCT for image uniformity, spatial resolution, and CT numbers, and to compare the dose distribution from orthogonal beams. A Rando phantom was scanned and planned with intensity-modulated radiation therapy (IMRT). Finally, two nasopharyngeal cancer patients treated with IMRT had their CBCT image sets calculated for dose comparison.

Results

With 360° acquisition of CBCT and high-resolution reconstruction, the uniformity of CT number distribution was improved and the otherwise large variations for background and high-density materials were reduced significantly. The dose difference between FBCT and CBCT was < 2% in phantoms. In the Rando phantom and the patients, the dose?Cvolume histograms were similar. The corresponding isodose curves covering ?? 90% of prescribed dose on FBCT and CBCT were close to each other (within 2 mm). Most dosimetric differences were from the setup errors related to the interval changes in body shape and tumor response.

Conclusion

The specific CBCT acquisition, reconstruction, and CT number modification can generate accurate dose calculation for the potential use in adaptive radiotherapy.     

Tangential vs. defined radiotherapy in early breast cancer treatment without axillary lymph node dissection

Purpose

Recent studies have demonstrated low regional recurrence rates in early-stage breast cancer omitting axillary lymph node dissection (ALND) in patients who have positive nodes in sentinel lymph node dissection (SLND). This finding has triggered an active discussion about the effect of radiotherapy within this approach. The purpose of this study was to analyze the dose distribution in the axilla in standard tangential radiotherapy (SRT) for breast cancer and the effects on normal tissue exposure when anatomic level I–III axillary lymph node areas are included in the tangential radiotherapy field configuration.

Patients and methods

We prospectively analyzed the dosimetric treatment plans from 51 consecutive women with early-stage breast cancer undergoing radiotherapy. We compared and analyzed the SRT and the defined radiotherapy (DRT) methods for each patient. The clinical target volume (CTV) of SRT included the breast tissue without specific contouring of lymph node areas, whereas the CTV of DRT included the level I–III lymph node areas.

Results

We evaluated the dose given in SRT covering the axillary lymph node areas of level I–III as contoured in DRT. The mean V_D95?% of the entire level I–III lymph node area in SRT was 50.28?% (range, 37.31–63.24?%), V_D45 Gy was 70.1?% (54.8–85.4?%), and V_D40 Gy was 83.5?% (72.3–94.8?%). A significant difference was observed between lung dose and heart toxicity in SRT vs. DRT. The V_20 Gy and V_30 Gy of the right and the left lung in DRT were significantly higher in DRT than in SRT (p?<?0.001). The mean heart dose in SRT was significantly lower (3.93 vs. 4.72 Gy, p?=?0.005).

Conclusion

We demonstrated a relevant dose exposure of the axilla in SRT that should substantially reduce local recurrences. Furthermore, we demonstrated a significant increase in lung and heart exposure when including the axillary lymph nodes regions in the tangential radiotherapy field set-up.     

Comparison of a simple dose-guided intervention technique for prostate radiotherapy with existing anatomical image guidance methods

Objectives

A simple dose-guided intervention technique for prostate radiotherapy using an isodose overlay method combined with soft-tissue-based corrective couch shifts has been proposed previously. This planning study assesses the potential clinical impact of such a correction strategy.

Methods

10 patients, each with 8–11 on-treatment CT studies (n=97), were assessed using this technique and compared with no intervention, bony anatomy intervention and soft-tissue intervention methods. Each assessment technique used a 4-mm action level for intervention. Outcomes were evaluated using measures of sensitivity, specificity and dosimetric effect, and compared across intervention techniques. Dosimetric effect was defined as the change in dosimetric coverage by the 95% isodose from the no intervention case of an evaluation construct called the verification target volume.

Results

Bony anatomy, soft tissue and dosimetric overlay-based interventions demonstrated sensitivity of 0.56, 0.73 and 1.00 and specificity of 0.64, 0.20 and 0.66, respectively. A detrimental dosimetric effect was shown in 7% of interventions for each technique, with benefit in 30%, 35% and 55% for bony anatomy, soft tissue and dosimetric overlay techniques, respectively.

Conclusion

Used in conjunction with soft-tissue-based corrective couch shifts, the dosimetric overlay technique allows effective filtering out of dosimetrically unnecessary interventions, making it more likely that any intervention made will result in improved target volume coverage.Image-guided radiotherapy (IGRT) aims to improve treatment delivery accuracy by visualising the patient''s anatomy immediately prior to treatment, comparing this with the localisation data, usually a CT scan, and identifying and compensating for inaccuracies in the set up or target position that would compromise treatment efficacy [1]. In cancer of the prostate, potential inaccuracies include misalignments of the patient, e.g. caused by pelvic rotation or skin drag against the treatment couch, or changes in internal anatomy as a result of motion caused by bladder or rectal filling.Planar megavoltage (MV) imaging using electronic portal imaging devices has long been used to verify bony anatomy position [2] and, in recent years, the increased availability of kilovoltage and three-dimensional MV in-room imaging systems has enabled soft-tissue visualisation [3-6]. Image-based correction using translational couch shifts is now routine practice in modern radiotherapy centres, with bony anatomy, fiducial marker and soft-tissue-based assessment protocols being well documented [7-12].In prostate radiotherapy, moving from bony anatomy to soft-tissue-based assessment and intervention changes the approach from a surrogate for target position to tracking the target itself. Logically this should improve treatment accuracy, since the effect of internal motion on prostate position should be directly taken into account. However, clinical intervention strategies assume that any breach of a defined action level always requires a corrective shift and takes no account of the expected dose distribution in the patient.Systematic and random error components of the margin between the clinical target volume (CTV) and the planning target volume (PTV) mean that dosimetric coverage of the CTV will not be compromised if, despite changes in position, it remains within the International Commission on Radiation Units and Measurements (ICRU) 50/62-compliant 95% dose “cloud” [13,14]. In such a case, clinical intervention would not be necessary. Using dose-guided radiotherapy, the coverage of the daily verification CTV (vCTV) could be assessed against the expected daily dose distribution. An informed decision on the need to intervene could then be made based on probable dosimetric coverage, taking account of remaining uncertainties.Such an online dose-guided technique could be performed using a full dose recalculation based on the daily on-treatment anatomy immediately prior to treatment delivery. However, the implementation of any online dose-guided intervention poses a number of logistical problems: it would be time consuming, require prompt access to treatment planning stations, be prone to error because of the short decision time available and is a significant role extension for treatment staff more used to anatomical matching techniques. An alternative technique would be to use a sufficiently accurate surrogate for a full dose calculation, allowing dose-based judgements without the need for a potentially time-consuming calculation while a patient is in the treatment position.A previous paper proposed a dosimetric overlay method for dose-based assessment in image-guided radiotherapy of the prostate [15]. The technique involved the use of an overlay of the treatment plan 95% isodose over an on-treatment verification CT scan, achieved by a quick CT reference point registration between the verification CT scan and the localisation planning scan. The isodose could then be used in lieu of a full recalculation of the dose distribution on the pre-treatment scan and used to assess the adequacy of CTV coverage on that day. The paper showed that the technique was a feasible and acceptable means of assessment for prostate radiotherapy and that uncertainties between a full recalculation and this overlay isodose for a given patient anatomy were quantifiable and reasonable.This paper describes a planning study performed to determine the efficacy of the dosimetric evaluation technique described in Smyth et al [15] compared with both existing bony anatomy and soft tissue-matching and intervention protocols. Issues around future clinical implementation of the dosimetric overlay technique will also be discussed.     

Is it necessary to repeat CT imaging and replanning during the course of intensity-modulated radiation therapy for locoregionally advanced nasopharyngeal carcinoma?

Purpose

Our aim was to evaluate the volumetric and dosimetric changes of target volumes and organs at risk (OARs) during intensity-modulated radiation therapy (IMRT) for locoregionally advanced nasopharyngeal carcinoma (NPC) and the necessity of replanning.

Materials and methods

Twenty locoregionally advanced NPC patients treated by concurrent chemotherapy and IMRT were included. CT and MR images were acquired before treatment and at weeks 2, 3, 4, 5 and 6 during treatment. The target volumes and OARs were contoured based on the fused CT-MRI images and hybrid plans were generated. The changes of volume and dosimetry were measured by comparing original plan and hybrid plans.

Results

Significant volumetric changes of target volumes and parotid gland were observed. The primary nasopharyngeal tumor (GTVnx), CTV1, involved lymph nodes (GTVnd) and left and right parotid glands, shrank at a mean rate of 14.7, 11.56, 11.40, 6.54 and 6.78 % per treatment week, respectively. There were no significant dosimetric changes in GTVnx, GTVnd, CTV1, spinal cord and brain stem while the differences of dose to left and right parotid glands were significant (F = 6.73, P = 0.007; F = 7.43, P = 0.007).

Conclusions

Remarkable volumetric changes were observed. However, the dosimetric changes were inconspicuous except for the parotid. Replanning might contribute to protect the parotid gland.     

Volumetric evaluation of an alternative bladder point in brachytherapy for locally advanced cervical cancer

Purpose

To evaluate an alternative dose point, so-called ALG (for Alain Gerbaulet), for the bladder in comparison to the International Commission on Radiation Units and Measurements (ICRU) point and D2cm³ (minimal dose to maximally exposed 2 cm³) in a large cohort of patients with locally advanced cervical cancer treated with external beam radiotherapy followed by image-guided pulsed dose rate brachytherapy.

Methods and materials

For each patient, the ALG point was constructed 1.5 cm above the ICRU bladder, parallel to the tandem (coronal and sagittal planes). The dosimetric data from 162 patients were reviewed.

Results

Average doses to ALG and bladder points were 19.40 Gy?±?7.93 and 17.14?±?8.70, respectively (p?=?0.01). The 2 cm³ bladder dose averaged 24.40?±?6.77 Gy. Ratios between D2cm³ and dose points were 1.37?±?0.46 and 1.68?±?0.74 (p?<?0.001) for ALG and ICRU points, respectively. Both dose points appeared correlated with D2cm³ (p?<?0.001) with coefficients of determination (R²) of 0.331 and 0.399 respectively. The estimated dose to the ICRU point of the rectum was 12.77?±?4.21 and 15.76?±?5.94 for D2cm³ (p?<?0.0001). Both values were significantly correlated (p?<?0.0001, R²?=?0.485).

Conclusion

The ALG point underestimates the D2cm³, but its mean on a large cohort is closer to D2cm³ than the dose to ICRU point. However, it shows great variability between cases and the weak strength of its correlation to D2cm³ indicates that it is not a good surrogate for individual volumetric evaluation of the dose D2cm³.     

Node-positive left-sided breast cancer: does VMAT improve treatment plan quality with respect to IMRT?

Purpose

The aim of the present work was to explore plan quality and dosimetric accuracy of intensity-modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) for lymph node-positive left-sided breast cancer.

Methods

VMAT and IMRT plans were generated with the Pinnacle³ V9.0 treatment planning system for 10 lymph node-positive left-sided breast cancer patients. VMAT plans were created using a single arc and IMRT was performed with 4 beams using 6, 10, and 15 MV photon energy, respectively. Plans were evaluated both manually and automatically using ArtiView?. Dosimetric plan verification was performed with a 2D ionization chamber array placed in a full scatter phantom.

Results

Photon energy had no significant influence on plan quality for both VMAT and IMRT. Large variability in low doses to the heart was found due to patient anatomy (range V_5 Gy 26.5–95?%). Slightly more normal tissue dose was found for VMAT (e.g., V_Tissue30%?=?22?%) than in IMRT (V_Tissue30%?=?18?%). The manual and ArtiView? plan evaluation coincided very accurately for most dose metrics (difference <?1?%). In VMAT, 96.7?% of detector points passed the 3?%/3 mm gamma criterion; marginally better accuracy was found in IMRT (98.3?%).

Conclusion

VMAT for node-positive left-sided breast cancer retains target homogeneity and coverage when compared to IMRT and allows maximum doses to organs at risk to be reduced. ArtiView? enables fast and accurate plan evaluation.     

Comparison of IMRT and VMAT plans with different energy levels using Monte-Carlo algorithm for prostate cancer

Purpose

To make dosimetric comparisons of volumetric-modulated arc therapy (VMAT) and 7-field intensity-modulated radiotherapy (IMRT) with dynamic MLCs using the Monaco treatment planning system with Monte Carlo algorithm.

Materials and methods

Single-arc VMAT and 7-field IMRT treatment plans were compared for 12 intermediate risk prostate cancer patients treated with prostate and seminal vesicle radiotherapy. For all patients, the prescribed dose was 78 Gy delivered in 39 fractions. The dosimetric data of IMRT and VMAT plans with 6, 10 and 15 MV energies were compared. The comparison was made for target volume, organs at risk (OAR) doses, and for monitor units (MU).

Results

The normal tissue surrounding the target were lower in VMAT plans compared to IMRT plans. VMAT plans achieved lower doses to all OARs for nearly all dosimetric endpoints. VMAT plans achieved 9.4, 9.0 and 7.0 % relative decrease in MUs required for RT delivery, for 6, 10 and 15 MV energy levels, respectively. The target volume and OAR dosimetric values did not differ significantly between 6, 10 and 15 MV photon energies.

Conclusion

VMAT plans were found to be dosimetrically equivalent to IMRT plans for prostate cancer patients, with better rectum and bladder sparing and fewer MUs required.     

In-vivo comparison of the acute retention of stem cell derivatives and fibroblasts after intramyocardial transplantation in the mouse model

Purpose

Various strategies have been applied to increase the engraftment of an intramyocardial cell transplant (Tx) to treat ischemic myocardium. Thereby, co-transplanted fibroblasts (FB) improve the long-term survival of stem cell derivatives (SCD) in a murine model of myocardial infarction. For therapeutic use, the time frame in which FB exert putative supportive effects needs to be identified. Therefore, we tracked the biodistribution and retention of SCD and FB in vivo using highly sensitive positron emission tomography (PET) imaging.

Methods

Murine [¹⁸?F]-fluorodeoxyglucose (FDG) labeled SCD and FB were transplanted after left anterior descending artery (LAD) ligation into the border zone of the ischemic area in female C57BL/6 mice. Cardiac retention and biodistribution during the initial 2 h after injection were measured via PET imaging.

Results

Massive initial cell loss occurred independently of the cell type. Thereby, FB were retained slightly, yet significantly better than SCD until 60 min post-injection (7.5?±?1.7 vs. 5.2?±?0.7 % ID at 25 min and 7.0?±?1.5 vs. 4.8?±?0.8 % ID at 60 min). Thereafter, a fraction of ～5 % that withstood the massive initial washout remained at the site of injection independently of the applied cell type (120 min, SCD vs. FB P?=?0.64). Most of the lost cells were detected in the lungs (～30 % ID).

Conclusions

We were able to quantitatively define the retention and biodistribution of different cell types via PET imaging in a mouse model after intramyocardial Tx. The utmost accuracy was achieved through this cell- and organ-specific approach by correcting PET data for cellular FDG efflux. Thereby, we observed a massive initial cell loss of ～95 %, causing low rates of long-term engraftment for both SCD and FB. We conclude that FB are not privileged compared to SCD regarding their acute retention kinetics, and therefore exert their beneficial effects at a later time point.     

Where is the most common site of DVT? Evaluation by CT venography

Purpose

Our aim was to clarify the common site of deep venous thrombosis (DVT) in patients suspected of having pulmonary embolism using computed tomography pulmonary angiography with computed tomography venography (CTV).

Materials and methods

We evaluated 215 patients. For all studies, 100?ml of 370?mg?I/ml nonionic contrast material was administered. CTV were scanned with helical acquisition starting at 3?min in four-slice multidetector-row computed tomography (MDCT) or 5?min in 64-MDCT after the start of contrast material injection. The site of DVT was divided into iliac vein, femoral vein, popliteal vein, or calf vein. Calf vein was divided into muscular (soleal and gastrocnemius) and nonmuscular (anterior/posterior tibial and peroneal) veins. The 2?×?2 chi-square test was used.

Results

One hundred and thirty-seven patients showed DVT; the muscular calf vein was more prevalent than other veins (P?Conclusions Our study showed that the most common site of DVT was the muscular calf vein.     

Impact of a rectal and bladder preparation protocol on prostate cancer outcome in patients treated with external beam radiotherapy

Purpose and objective

To test the hypothesis that a rectal and bladder preparation protocol is associated with an increase in prostate cancer specific survival (PCSS), clinical disease free survival (CDFS) and biochemical disease free survival (BDFS).

Patients and methods

From 1999 to 2012, 1080 prostate cancer (PCa) patients were treated with three-dimensional conformal radiotherapy (3DCRT). Of these patients, 761 were treated with an empty rectum and comfortably full bladder (RBP) preparation protocol, while for 319 patients no rectal/bladder preparation (NRBP) protocol was adopted.

Results

Compared with NRBP patients, patients with RBP had significantly higher BDFS (64% vs 48% at 10 years, respectively), CDFS (81% vs 70.5% at 10 years, respectively) and PCSS (95% vs 88% at 10 years, respectively) (log-rank test p < 0.001). Multivariate analysis (MVA) indicated for all treated patients and intermediate high-risk patients that the Gleason score (GS) and the rectal and bladder preparation were the most important prognostic factors for PCSS, CDFS and BDFS. With regard to high- and very high-risk patients, GS, RBP, prostate cancer staging and RT dose were predictors of PCSS, CDFS and BDFS in univariate analysis (UVA).

Conclusion

We found strong evidence that rectal and bladder preparation significantly decreases biochemical and clinical failures and the probability of death from PCa in patients treated without daily image-guided prostate localization, presumably since patients with RBP are able to maintain a reproducibly empty rectum and comfortably full bladder across the whole treatment compared with NRPB patients.

     

Subtracted 3D CT angiography for the evaluation of intracranial aneurysms in 256-slice multidetector CT: usefulness of the 80-kVp plus compact contrast medium bolus protocol

Objectives

To evaluate the usefulness of an 80-kVp and compact contrast material protocol for arterial phase subtracted cerebral 3D-CTA using 256-slice multidetector CT.

Methods

Thirty-two patients underwent CT with 100 kVp and received a contrast dose of 370 mgI/kg body weight over 15 s (protocol A). Thirty-three patients underwent CT with 100 kVp and received a contrast dose of 296 mgI/kg body weight over 10 s (protocol B). Thirty-three other patients underwent CT with 80 kVp and received a contrast medium dose of 296 mgI/kg body weight over 10 s (protocol C). We compared the arterial attenuation and contrast noise ratio (CNR) of each protocol. Two independent readers assessed overall image quality.

Results

Arterial attenuation was significantly higher under protocols A (418.6?±?71.1 HU) and C (442.7?±?79.3 HU) than under protocol B (355.8?±?107.2 HU; P?<?0.05). The CNR of protocol C (26.1?±?6.1) was higher than that of protocol A (20.7?±?8.4; P?<?0.05). The overall image quality of protocol A was higher than that of protocol C (P?<?0.01).

Conclusion

The 80-kVp plus compact contrast protocol is well suited to arterial phase subtracted cerebral 3D-CTA without confounding venous enhancement.

Key Points

? Subtracted 3D CT angiography is useful in the evaluation of intracranial aneurysms. ? A compact contrast material protocol increased arterial attenuation without venous contamination. ? Low-kVp CT compensated for the decreased amount of contrast medium. ? An 80-kVp CT with a compact enhancement bolus provides good intracranial 3D-CT angiography.     

Post-mortem whole body computed tomography of opioid (heroin and methadone) fatalities: frequent findings and comparison to autopsy

Objective

To investigate frequent findings in cases of fatal opioid intoxication in whole-body post-mortem computed tomography (PMCT).

Methods

PMCT of 55 cases in which heroin and/or methadone had been found responsible for death were retrospectively evaluated (study group), and were compared with PMCT images of an age- and sex-matched control group. Imaging results were compared with conventional autopsy.

Results

The most common findings in the study group were: pulmonary oedema (95 %), aspiration (66 %), distended urinary bladder (42 %), cerebral oedema (49 %), pulmonary emphysema (38 %) and fatty liver disease (36 %). These PMCT findings occurred significantly more often in the study group than in the control group (p?<?0.05). The combination of lung oedema, brain oedema and distended urinary bladder was seen in 26 % of the cases in the study group but never in the control group (0 %). This triad, as indicator of opioid-related deaths, had a specificity of 100 %, as confirmed by autopsy and toxicological analysis.

Conclusions

Frequent findings in cases of fatal opioid intoxication were demonstrated. The triad of brain oedema, lung oedema and a distended urinary bladder on PMCT was highly specific for drug-associated cases of death.

Key Points

? Frequent findings in cases of fatal opioid intoxication were investigated. ? Lung oedema, brain oedema and full urinary bladder represent a highly specific constellation. ? This combination of findings in post-mortem CT should raise suspicion of intoxication.     

Adjuvant intensity-modulated proton therapy in malignant pleural mesothelioma

Purpose

Intensity-modulated radiation therapy (IMRT) is the state-of-the-art treatment for patients with malignant pleural mesothelioma (MPM). The goal of this work was to assess whether intensity-modulated proton therapy (IMPT) could further improve the dosimetric results allowed by IMRT.

Patients and methods

We re-planned 7 MPM cases using both photons and protons, by carrying out IMRT and IMPT plans. For both techniques, conventional dose comparisons and normal tissue complication probability (NTCP) analysis were performed. In 3?cases, additional IMPT plans were generated with different beam dimensions.

Results

IMPT allowed a slight improvement in target coverage and clear advantages in dose conformity (p?mean reduction of 9.5?Gy, p?=?0.001) and ipsilateral kidney (V₂₀ reduction of 58%, p?=?0.001), together with a very large reduction of mean dose for the contralateral lung (0.2?Gy vs 6.1?Gy, p?=?0.0001). NTCP values for the liver showed a systematic superiority of IMPT with respect to IMRT for both the esophagus (average NTCP 14% vs. 30.5%) and the ipsilateral kidney (p?=?0.001). Concerning plans obtained with different spot dimensions, a slight loss of target coverage was observed along with sigma increase, while maintaining OAR irradiation always under planning constraints.

Conclusion

Results suggest that IMPT allows better OAR sparing with respect to IMRT, mainly for the liver, ipsilateral kidney, and contralateral lung. The use of a spot dimension larger than 3?×?3?mm (up to 9?×?9?mm) does not compromise dosimetric results and allows a shorter delivery time.     

Erectile dysfunction after prostate three-dimensional conformal radiation therapy

Purpose

Erectile dysfunction is associated with all the common treatment options for prostate cancer. The aim of this research was to evaluate the relationship between erectile function and radiation dose to the penile bulb (PB) and other proximal penile structures in men receiving conformal radiotherapy (CRT) without hormonal therapy (HT) for prostate cancer, whose sexual function was known before treatment.

Patients and methods

The study included 19 patients treated with 3D-CRT for localized prostate cancer at our department, who were self-reported to be potent before treatment, had not received HT, and had complete follow-up data available. Our evaluation was based on the International Index of Erectile Function (IIEF-5). Dose–volume histograms (DVHs) were used to evaluate the dose to the PB. Statistical analysis was performed with an unconditional logistic regression model.

Results

All patients reported change in potency after radiation. Eight patients (42%) remained potent but showed a decrease of 1 or 2 levels of potency, as defined by the IIEF-5 questionnaire (reduced potency group), while 11 patients (58%) reported a change of higher levels and revealed a severe erectile dysfunction after 2?years (impotence group). Multivariate analysis of morphological and dosimetric variables yielded significance for the mean dose (p?=?0.05 with an odds ratio of 1.14 and 95% CI 1–1.30). Patients receiving a mean dose of less than 50?Gy to the PB appear to have a much greater likelihood of maintaining potency.

Conclusion

Our data suggest a possible existence of a dose–volume correlation between the dose applied to the PB and radiation-induced impotence.     

RapidArc combined with the active breathing coordinator provides an effective and accurate approach for the radiotherapy of hepatocellular carcinoma

Purpose

The goal of this research was to investigate the feasibility of volumetric modulated arc therapy, RapidArc (RA), in association with the active breathing coordinator (ABC) for the treatment of hepatocellular carcinoma (HCC) with radiotherapy.

Patients and materials

A total of 12?patients with HCC, after receiving transcatheter arterial chemoembolization (TACE) treatment, underwent three-dimensional computer tomography (3D-CT) scanning associated with ABC using end inspiration hold (EIH), end expiration hold (EEH), and free breathing (FB) techniques. The three-dimensional conformal radiotherapy (3D-CRT), intensity-modulated radiotherapy (IMRT), and RA plans (three 135° arcs) were designed on different CT images, respectively. The liver volume, gross tumor volume (GTV), and planning target volume (PTV) of the three breath status and the dosimetric differences of the different plans were compared.

Results

There were no significant differences in the volumes of live and GTV between the three breathing techniques (p?>?0.05); the PTV in FB was greater than in the EEH and EIH (p?20, V₃₀, and V₄₀ of normal liver compared to 3D-CRT, while the V₅ and V₁₀ in RA were higher than in IMRT. The mean values in mean dose, V₁₀, V₂₀, V₃₀, and V₄₀ of the normal liver were reduced from 13.12?Gy, 46%, 24%, 13%, and 8% in RA_FB to 10.23?Gy, 35%, 16%, 8%, and 5% in RA_EEH and 9.23?Gy, 32%, 16%, 8%, and 5% in RA_EIH?, respectively. In addition, the treatment time of RA was equal to 3D-CRT, which was significantly shorter than IMRT.

Conclusion

RA in conjunction with ABC for the treatment of HCC with radiotherapy can achieve better dose delivery and ensure the accuracy of the target volume, which spares more organs at risk, uses fewer monitor units, and shortens treatment time.     

Diagnostic accuracy of 128-slice dual-source CT coronary angiography: a randomized comparison of different acquisition protocols

Objectives

To compare the diagnostic performance and radiation exposure of 128-slice dual-source CT coronary angiography (CTCA) protocols to detect coronary stenosis with more than 50 % lumen obstruction.

Methods

We prospectively included 459 symptomatic patients referred for CTCA. Patients were randomized between high-pitch spiral vs. narrow-window sequential CTCA protocols (heart rate below 65 bpm, group A), or between wide-window sequential vs. retrospective spiral protocols (heart rate above 65 bpm, group B). Diagnostic performance of CTCA was compared with quantitative coronary angiography in 267 patients.

Results

In group A (231 patients, 146 men, mean heart rate 58?±?7 bpm), high-pitch spiral CTCA yielded a lower per-segment sensitivity compared to sequential CTCA (89 % vs. 97 %, P?=?0.01). Specificity, PPV and NPV were comparable (95 %, 62 %, 99 % vs. 96 %, 73 %, 100 %, P?>?0.05) but radiation dose was lower (1.16?±?0.60 vs. 3.82?±?1.65 mSv, P?<?0.001). In group B (228 patients, 132 men, mean heart rate 75?±?11 bpm), per-segment sensitivity, specificity, PPV and NPV were comparable (94 %, 95 %, 67 %, 99 % vs. 92 %, 95 %, 66 %, 99 %, P?>?0.05). Radiation dose of sequential CTCA was lower compared to retrospective CTCA (6.12?±?2.58 vs. 8.13?±?4.52 mSv, P?<?0.001). Diagnostic performance was comparable in both groups.

Conclusion

Sequential CTCA should be used in patients with regular heart rates using 128-slice dual-source CT, providing optimal diagnostic accuracy with as low as reasonably achievable (ALARA) radiation dose.

Key Points

? 128-slice dual-source CT coronary angiography offers several different acquisition protocols. ? Randomized comparison of protocols reveals an optimal protocol selection strategy. ? Appropriate CTCA protocol selection lowers radiation dose, while maintaining high quality. ? CTCA protocol selection should be based on individual patient characteristics. ? A prospective sequential protocol is preferred for CTCA.