[en] To assess the extent of extra imaging beyond the prescribed anatomical margins for chest and abdominal CT and to determine associated extra patient and organ dose estimates. For 167 consecutive patients undergoing routine chest and/or abdominal examination with 128-slice CT, extra imaging length was evaluated on coronal images. Effective and organ doses (thyroid, liver, breasts, testes) were calculated. Paired t-test was applied to evaluate statistically significant differences between prescribed and actual imaging length, and associated doses. 133 (80%) examinations had extra coverage (mean 4.6 cm, range 1-19.5 cm). Significantly higher (P < 0.05) effective doses for chest CT (mean 4.8 mSv vs 4.2 mSv for actual vs prescribed volume of interest), abdominal CT (8.4 mSv vs 7.9 mSv) or thorax-abdominal CT (12.8 mSv vs 11.9 mSv) were found. A significantly higher (P < 0.001) organ dose was estimated for thyroid (extra dose 99% corresponding to 5.1 mSv), liver (56%, 2.2 mSv), testes (115%, 7.6 mSv), and breasts (163%, 1.5 mSv). Imaging beyond anatomical limits during routine chest and abdominal CT results in higher organ and effective doses. Continuous training of the technologists remains important. Physicians and technologists must be kept aware of the additional dose associated with extra imaging. (orig.)

[en] Purpose: Two approaches have been suggested for escalating the total dose in radiotherapy treatment of prostate cancer. One is conformal radiotherapy; the other is hyperfractionation using many small fractions. Both imply some possible prolongation in overall treatment time. To judge whether prolonged treatment schedules would be detrimental, it is necessary to know the proliferation rates in human prostate tumors, specifically, the potential doubling time (Tpot). There is a lack of data on this parameter in the literature. Methods and Materials: Seven patients with adenocarcinoma of the prostate were studied. A tracer dose of 100 mg/m² of IUdR was infused intravenously 4-12 h before biopsies were taken. Biopsies were fixed in 70% ethanol, stored at 4 deg. C, and later prepared and stained by standard methods for flow cytometry, using the red fluorescence signal for DNA and the green fluorescence signal (fluorescein isothiocyanate) for 5-iodo-2'-deoxyuridine. The duration of DNA synthesis (Ts) was determined by the relative movement (RM) method, knowing the interval between tracer administration and biopsy. Tpot was calculated as the quotient of Ts by labeling index (LI). Results: In two of the seven tumors the LI was too low (<0.6%) for a reliable estimate of RM to be made, so no determination of Tpot was possible for these tumors. The mean LI values in the other five tumors were 2.4%, 1.4%, 1.0%, 3.0%, and 0.9%. The durations of Ts were 13.2, 9.5, 10.0, 11.7, and 12.7 h, respectively. The resulting values of Tpot were 23, 28, 42, 16, and 61 days, respectively. Conclusion: The low labeling indices in prostate tumors, also reported by others, made estimation of Ts by RM impossible in about a third of these tumors. However, five tumors yielded long estimates for Tpot, implying that prolongation from 6 to about 8 weeks should not be detrimental

[en] Purpose: To investigate whether the use of transaxial and coronal MR imaging improves the ability to localize the apex of the prostate and the anterior part of the rectum compared to the use of transaxial CT alone, and whether the incorporation of MR could improve the coverage of the prostate by the radiotherapy field and change the volume of rectum irradiated. Methods and Materials: Ten consecutive patients with localized prostate carcinoma underwent a CT and an axial and coronal MR scan in treatment position. The CT and MR images were mathematically aligned, and three observers were asked to contour independently the prostate and the rectum on CT and on MR. The interobserver variability of the prostatic apex location and of the delineation of the anterior rectal wall were assessed for each image modality. A dosimetry study was performed to evaluate the dose to the rectum when MR was used in addition to CT to localize the pelvic organs. Results: The interobserver variation of the prostatic apex location was largest on CT ranging from 0.54 to 1.07 cm, and smallest on coronal MR ranging from 0.17 to 0.25 cm. The interobserver variation of the delineation of the anterior rectum on MR was small and constant along the whole length of the prostate (0.09 ± 0.02 cm), while for CT it was comparable to that for the MR delineation at the base of the prostate, but it increased gradually towards the apex, where the variation reached 0.39 cm. The volume of MR rectum receiving more than 80% of the prescribed dose was on average reduced by 23.8 ± 11.2% from the CT to the MR treatment plan. Conclusion: It can be concluded that the additional use of axial and coronal MR scans, in designing the treatment plan for localized prostate carcinoma, improves substantially the localization accuracy of the prostatic apex and the anterior aspect of the rectum, resulting in a better coverage of the prostate and a potential to reduce the volume of the rectum irradiated to a high dose

[en] The aim of this study was to compare dose and image quality (IQ) of a baseline low-dose computed tomography (CT) (fix mAs) vs. an ultra-low-dose CT (automatic tube current modulation, ATCM) in patients with suspected urinary stone disease and to assess the added value of iterative reconstruction. CT examination was performed on 193 patients (103 baseline low-dose, 90 ultra-low-dose). Filtered back projection (FBP) was used for both protocols, and Sinogram Affirmed Iterative Reconstruction (SAFIRE) was used for the ultra-low-dose protocol only. Dose and ureter stones information were collected for both protocols. Subjective IQ was assessed by two radiologists scoring noise, visibility of the ureter and overall IQ. Objective IQ (contrast-to-noise ratio, CNR) was assessed for the ultra-low-dose protocol only (FBP and SAFIRE). The ultra-low-dose protocol (ATCM) showed a 22% decrease in mean effective dose ( p < 0.001) and improved visibility of the pelvic ureter (p = 0.02). CNR was higher for SAFIRE (p < 0.0001). SAFIRE improves the objective IQ, but not the subjective IQ for the chosen clinical task. (authors)

[en] To assess acute (primary endpoint) and late toxicity, quality of life (QOL), biochemical or clinical failure (secondary endpoints) of a hypofractionated IMRT schedule for prostate cancer (PC). 38 men with localized PC received 66 Gy (2.64 Gy) to prostate,2 Gy to seminal vesicles (50 Gy total) using IMRT. Acute toxicity was evaluated weekly during radiotherapy (RT), at 1–3 months afterwards using RTOG acute scoring system. Late side effects were scored at 6, 9, 12, 16, 20, 24 and 36 months after RT using RTOG/EORTC criteria. Quality of life was assessed by EORTC-C30 questionnaire and PR25 prostate module. Biochemical failure was defined using ASTRO consensus and nadir+2 definition, clinical failure as local, regional or distant relapse. None experienced grade III-IV toxicity. 10% had no acute genito-urinary (GU) toxicity, 63% grade I; 26% grade II. Maximum acute gastrointestinal (GI) scores 0, I, II were 37%, 47% and 16%. Maximal acute toxicity was reached weeks 4–5 and resolved within 4 weeks after RT in 82%. Grade II rectal bleeding needing coagulation had a peak incidence of 18% at 16 months after RT but is 0% at 24–36 months. One developed a urethral stricture at 2 years (grade II late GU toxicity) successfully dilated until now. QOL urinary symptom scores reached a peak incidence 1 month after RT but normalized 6 months later. Bowel symptom scores before, at 1–6 months showed similar values but rose slowly 2–3 years after RT. Nadir of sexual symptom scores was reached 1–6 months after RT but improved 2–3 years later as well as physical, cognitive and role functional scales. Emotional, social functional scales were lowest before RT when diagnosis was given but improved later. Two years after RT global health status normalized. This hypofractionated IMRT schedule for PC using 25 fractions of 2.64 Gy did not result in severe acute side effects. Until now late urethral, rectal toxicities seemed acceptable as well as failure rates. Detailed analysis of QOL questionnaires resulted in the same conclusion

[en] Routine PSA testing has led to diagnosis and treatment of prostate cancer at earlier stages than previously. Earlier and technically-improved treatment, together with escalation of dose has enhanced cure rates. Although, the incidence of nodal metastases is now lower than in pre-PSA days, more extended pelvic lymphadenectomies have shown the actual rate of lymph node involvement to be higher than had been determined from standard radical prostate surgery. As in cancers in other sites, especially in their earlier stages, lymph node metastases may exist in the absence of haematogenous dissemination. This, together with the improved rates of control of the primary prostate tumour, suggests that elective irradiation of early-stage lymph nodes from prostate cancer should enhance survival in a manner analogous to improvements seen with this approach in other cancers. Although, the absolute incidence of positive nodes in locally advanced prostate cancer warrants elective radiotherapy, it is relatively low and the modest improvements to be expected may be undetected in the results of a small trial

[en] Purpose: To date no guidelines are available for contouring prostate cancer inside the gland, as visible on multiparametric (mp-) MRI. We assessed inter-institutional differences in interpretation of mp-MRI in the multicenter phase III FLAME trial.

[en] Introduction: Intrafractional motion consists of two components: (1) the movement between the on-line repositioning procedure and the treatment start and (2) the movement during the treatment delivery. The goal of this study is to estimate this intrafractional movement of the prostate during prostate cancer radiotherapy. Material and methods: Twenty-seven patients with prostate cancer and implanted fiducials underwent a marker match procedure before a five-field IMRT treatment. For all fields, in-treatment images were obtained and then processed to enable automatic marker detection. Combining the subsequent projection images, five positions of each marker were determined using the shortest path approach. The residual set-up error (RSE) after kV-MV based prostate localization, the prostate position as a function of time during a radiotherapy session and the required margins to account for intrafractional motion were determined. Results: The mean RSE and standard deviation in the antero-posterior, cranio-caudal and left-right direction were 2.3 ± 1.5 mm, 0.2 ± 1.1 mm and -0.1 ± 1.1 mm, respectively. Almost all motions occurred in the posterior direction before the first treatment beam as the percentage of excursions >5 mm was reduced significantly when the RSE was not accounted for. The required margins for intrafractional motion increased with prolongation of the treatment. Application of a repositioning protocol after every beam could decrease the 1 cm margin from CTV to PTV by 2 mm. Conclusions: The RSE is the main contributor to intrafractional motion. This RSE after on-line prostate localization and patient repositioning in the posterior direction emphasizes the need to speed up the marker match procedure. Also, a prostate IMRT treatment should be administered as fast as possible, to ensure that the pre-treatment repositioning efforts are not erased by intrafractional prostate motion. This warrants an optimized workflow with the use of faster treatment techniques.

[en] PSMA-PET has become the PET technique of choice to localise the site of biochemically recurrent prostate cancer (PCa). With hybrid PET/MRI, the advantages of MRI are added to molecular characteristic of PET. The aim of this study was to investigate the incremental value of PET/MR versus PET/CT in patients with biochemically recurrent PCa by head-to-head comparison. Thirty-four patients with biochemically recurrent PCa were prospectively included. They underwent [${}^{68}$GA]Ga-PSMA-11 PET/CT, followed by simultaneous PET/MR. All PET (PET${}_{CT}$, PET${}_{MR}$), CT and MR images were evaluated for number of lesions and location. The number of lesions at specific sites was compared using Wilcoxon-sign-rank test. For PET, the maximum and mean standardised uptake values (SUVs) were calculated for each lesion compared using a two-sided paired t test. PET${}_{CT}$ and PET${}_{MR}$ scans were positive in 19 and 20 patients, detecting 73 and 79 lesions respectively. All lesions detected on PET${}_{CT}$ were also detected on PET${}_{MR}$. CT and MRI only were positive in 14 and 17 patients, detecting 38 and 50 lesions, respectively, which was significantly lower than PET${}_{CT}$ and PET${}_{MR}$ respectively. Combined interpretation showed more lesions on PET/MR than on PET/CT (88 vs 81). No significant difference in detection of presence of local recurrence nor distant metastases was found. SUV${}_{mean}$ and SUV${}_{max}$ values were significantly higher on PET${}_{MR}$ than on PET${}_{CT}$ in local recurrence and lymph node metastases. [${}^{68}$GA]Ga-PSMA-11 PET/MR was able to detect biochemically recurrent PCa at least as accurately as PET/CT for local recurrence, lymph node metastasis and distant metastasis. PSMA PET/MRI detects the location of biochemical recurrence at least as accurately as PET/CT. Substitution of PET/CT by PET/MRI adds sensitivity in PSMA lesion detection also in the setting of distant recurrence due to both the MR and TOF PET components.

[en] Objective: To determine predictors of technical success, dysfunction recurrence and patency after percutaneous transluminal angioplasty (PTA) of de novo dysfunctional hemodialysis arteriovenous fistulas (AVFs). Methods: Retrospective analysis of first time PTA of 167 AVF in 162 patients (100 men, 66 ± 13 years). Anatomical (location, length, grade and number of stenoses) and clinical variables (sex, age, prior AVF, diabetes mellitus and AVF age, side and location) were reviewed. Results: 217 stenoses or segmental occlusions were treated. Technical success rate (84.4%) was higher in radiocephalic AVF compared to brachial artery–median vein AVF (p = 0.030) and was negatively correlated with initial stenosis (p = 0.049). Dysfunction recurrence was seen in 52.7% and correlated negatively with technical success (p = 0.013) and AVF age (p = 0.008). Early dysfunction (within 6 months) was negatively correlated with AVF age (p = 0.016) and positively with diabetes (p = 0.003). Higher AVF age resulted in higher primary (p = 0.005) and secondary patency rates (p = 0.037–0.005). Conclusions: Technical success of PTA in hemodialysis AVF is affected by AVF type and initial stenosis and has significant effect on dysfunction recurrence, but not on AVF longevity. Younger AVF has increased risk for (early) recurrent dysfunction and lower patency rates. Patients with diabetes mellitus have higher risk for early dysfunction