Variation in accumulated dose of volumetric-modulated arc therapy for pancreatic cancer due to different beam starting phases.

PURPOSE: To assess the effects of different beam starting phases on dosimetric variations in the clinical target volume (CTV) and organs at risk (OARs), and to identify the relationship between plan complexity and the dosimetric impact of interplay effects in volumetric-modulated arc therapy (VMAT) plans for pancreatic cancer. METHODS: Single and double full-arc VMAT plans were generated for 11 patients. A dose of 50.4 Gy in 28 fractions was prescribed to cover 50% of the planning target volume. Patient-specific Digital Imaging and Communications in Medicine-Radiation Therapy plan files were divided into 10 files based on the respiratory phases in four-dimensional computed tomography (4DCT) simulations. The phase-divided VMAT plans were calculated in consideration of the beam starting phase for each arc and were then combined in the mid-ventilation phase of 4DCT (4D plans). The dose-volumetric parameters were compared with the calculated dose distributions without consideration of the interplay effects (3D plans). Additionally, relationships among plan parameters such as modulation complexity scores, monitor units (MUs), and dose-volumetric parameters were evaluated. RESULTS: Dosimetric differences in the median values associated with different beam starting phases were within ± 1.0% and ± 0.2% for the CTV and ± 0.5% and ± 0.9% for the OARs during single and double full-arc VMAT, respectively. Significant differences caused by variations in the beam starting phases were observed only for the dose-volumetric parameters of the CTV during single full-arc VMAT (P < 0.05), associated with moderate or strong correlations between the MUs and the dosimetric differences between the 4D and 3D plans. CONCLUSIONS: The beam starting phase affected CTV dosimetric variations of single full-arc VMAT. The use of double full-arc VMAT mitigated this problem. However, variation in the dose delivered to OARs was not dependent on the beam starting phase, even for single full-arc VMAT.

[Comparison of Monitor Unit between Electron Monte Carlo Algorithm by Different Dose Normalization Methods and Conventional Manual Calculation].

The purpose of this study was to evaluate the discrepancy between the monitor unit (MU) calculated by different dose normalization methods in the electron Monte Carlo (eMC) algorithm and the conventional manual MU. In the water phantom condition, the manual MU obtained from the measured output factor was compared with the calculated MU by the eMC algorithm, using 24 different irradiation field shapes and several different energies of electron beam. In the breast boost condition, calculated MUs by both calculation methods were evaluated for 45 cases. As a result, the MUs computed by the eMC algorithm in the water phantom varied according to the dose normalization methods, and the mean±standard deviation of the difference between the manual and calculated MU were 1.1±1.4%, 0.0±1.0% and 0.4±1.2% in peak depth normalization (PN), no plan normalization (NPN) and 100% at body maximum (100%BM), respectively. In breast-boost cases, the MU difference between the manual and the calculated MU were 6.1±3.7%, 3.4±2.8% and 1.1±2.9% in PN, NPN and 100%BM, respectively. We revealed that the resultant MU calculated by eMC algorithm was dependent on the dose normalization method and the averaged differences exceeded 6% in PN, especially in breast boost condition. When using the eMC in the breast boost condition, it is desirable to select an appropriate dose normalization method according to dose prescription policies at each facility.

Optimization of Couch Modeling in the Change of Dose Calculation Methods and Their Versions.

In external radiotherapy, the X-ray beam passes through the treatment couch, leading to the dose reduction by the attenuation of the couch. As a method to compensate for the reduction, radiation treatment planning systems (RTPS) support virtual couch function, namely "couch modeling method". In the couch modeling method, the computed tomography (CT) numbers assigned to each structure should be optimized by comparing calculations to measurements for accurate dose calculation. Thus, re-optimization of CT numbers will be required when the dose calculation algorithm or their version changes. The purpose of this study is to evaluate the calculation accuracy of the couch modeling method in different calculation algorithms and their versions. The optimal CT numbers were determined by minimizing the difference between measured transmission factors and calculated ones. When CT numbers optimized by Anisotropic Analytical Algorithm (AAA) Ver. 8.6 were used, the maximum and the mean difference of transmission factor were 5.8% and 1.5%, respectively, for Acuros XB (AXB) Ver. 11.0. However, when CT numbers optimized by AXB Ver. 11.0 were used, they were 2.6% and 0.6%, respectively. The CT numbers for couch structures should be optimized when changing dose calculation algorithms and their versions. From the comparison of the measured transmission to calculation, it was found that the CT numbers had high accuracy.

Dosimetric Verification around High-density Materials for External Beam Radiotherapy.

It is generally known that the dose distribution around the high-density materials is not accurate with commercially available radiation treatment planning systems (RTPS). Recently, Acuros XB (AXB) has been clinically available for dose calculation algorithm. The AXB is based on the linear Boltzmann transport equation - the governing equation - that describes the distribution of radiation particles resulting from their interactions with matter. The purpose of this study was to evaluate the dose calculation accuracy around high-density materials for AXB under three X-rays energy on the basis of measured values with EBT3 and compare AXB with various dose calculation algorithms (AAA, XVMC) in RTPS and Monte Carlo. First, two different metals, including titanium and stainless steel, were inserted at the center of a water-equivalent phantom, and the depth dose was measured with EBT3. Next, after a phantom which reproduced the geometry of measurement was virtually created in RTPS, dose distributions were calculated with three commercially available algorithms (AXB, AAA, and XVMC) and MC. The calculated doses were then compared with the measured ones. As a result, compared to other algorithms, it was found that the dose calculation accuracy of AXB at the exit side of high-density materials was comparable to that of MC and measured value with EBT3. However, note that AXB underestimated the dose up to approximately 30% at the plane of incidence because it cannot exactly estimate the impact of the backscatter.

Interfraction positional variation in pancreatic tumors using daily breath-hold cone-beam computed tomography with visual feedback.

We assessed interfraction positional variation in pancreatic tumors using daily breath-hold cone-beam computed tomography at end-exhalation (EE) with visual feedback (BH-CBCT). Eleven consecutive patients with pancreatic cancer who underwent BH intensity-modulated radiation therapy with visual feedback were enrolled. All participating patients stopped oral intake, with the exception of drugs and water, for > 3 hr before treatment planning and daily treatment. Each patient was fixed in the supine position on an individualized vacuum pillow. An isotropic margin of 5 mm was added to the clinical target volume to create the planning target volume (PTV). The prescription dose was 42 to 51 Gy in 15 fractions. After correcting initial setup errors based on bony anatomy, the first BH-CBCT scans were performed before beam delivery in every fraction. BH-CBCT acquisition was obtained in three or four times breath holds by interrupting the acquisition two or three times, depending on the patient's BH ability. The image acquisition time for a 360° gantry rotation was approximately 90 s, including the interruption time due to BH. The initial setup errors were corrected based on bony structure, and the residual errors in the target position were then recorded. The magnitude of the interfraction variation in target position was assessed for 165 fractions. The systematic and random errors were 1.2 and 1.8 mm, 1.1 and 1.8 mm, and 1.7 and 2.9 mm in the left-right (LR), anterior-posterior (AP), and superior-inferior (SI) directions, respectively. Absolute interfraction variations of > 5 mm were observed in 18 fractions (11.0%) from seven patients because of EE-BH failure. In conclusion, target matching is required to correct interfraction variation even with visual feedback, especially to ensure safe delivery of escalated doses to patients with pancreatic cancer.

Dosimetric evaluation of the Acuros XB algorithm for a 4 MV photon beam in head and neck intensity-modulated radiation therapy.

In this study, we assessed the differences in the dose distribution of a 4 MV photon beam among different calculation algorithms: the Acuros XB (AXB) algorithm, the analytic anisotropic algorithm (AAA), and the pencil beam convolution (PBC) algorithm (ver. 11.0.31), in phantoms and in clinical intensity-modulated radiation therapy (IMRT) plans. Homogeneous and heterogeneous, including middle-, low-, and high-density, phantoms were combined to assess the percentage depth dose and lateral dose profiles among AXB, AAA, and PBC. For the phantom containing the low-density area, AXB was in agreement with measurement within 0.5%, while the greatest differences between the AAA and PBC calculations and measurement were 2.7% and 3.6%, respectively. AXB showed agreement with measurement within 2.5% at the high-density area, while AAA and PBC overestimated the dose by more than 4.5% and 4.0%, respectively. Furthermore, 15 IMRT plans, calculated using AXB, for oropharyngeal, hypopharyngeal, and laryngeal carcinomas were analyzed. The dose prescription was 70 Gy to 50% of the planning target volume (PTV70). Subsequently, each plan was recalculated using AAA and PBC while maintaining the AXB-calculated monitor units, leaf motion, and beam arrangement. Additionally, nine hypopharyngeal and laryngeal cancer patients were analyzed in terms of PTV70 for cartilaginous structures (PTV(70_cartilage)). The doses covering 50% to PTV70 calculated by AAA and PBC were 2.1% ± 1.0% and 3.7% ± 0.8% significantly higher than those using AXB, respectively (p < 0.01). The increases in doses to PTV(70_cartilage) calculated by AAA and PBC relative to AXB were 3.9% and 5.3% on average, respectively, and were relatively greater than those in the entire PTV70. AXB was found to be in better agreement with measurement in phantoms in heterogeneous areas for the 4 MV photon beam. Considering AXB as the standard, AAA and PBC overestimated the IMRT dose for head and neck cancer. The dosimetric differences should not be ignored, particularly with cartilaginous structures in PTV.

Uterine artery pseudoaneurysm hidden behind septic abortion: pseudoaneurysm without preceding procedure.

Uterine artery pseudoaneurysm (UAP) can occur after cesarean section or traumatic delivery, usually manifesting as postpartum hemorrhage. Here we report a patient with UAP possibly caused by septic abortion. She had high fever and bleeding with positive urine pregnancy test. We diagnosed this condition as septic abortion. Ultrasound revealed an intrauterine echogenic mass and color Doppler revealed swirling blood flow within the mass. Contrast-enhanced computed tomography showed a heterogeneously enhanced intrauterine mass. Selective internal iliac artery angiography revealed contrast medium within the mass immediately after medium injection. Bilateral uterine artery embolization was performed, after which medium no longer accumulated in the uterus, and hemostasis was achieved, confirming the diagnosis as UAP. Antibiotic treatment ameliorated the infection and the uterine content was expelled and absorbed. UAP can occur even without preceding procedures and may manifest abortive, and not postpartum, hemorrhage. UAP may be hidden behind septic abortion.

Uterine artery pseudoaneurysm: not a rare condition occurring after non-traumatic delivery or non-traumatic abortion.

PURPOSE: Uterine artery pseudoaneurysm (UAP) is considered a rare disorder after traumatic delivery or traumatic pregnancy termination such as cesarean section or dilatation and curettage, initially manifesting as genital hemorrhage. Our clinical impression contradicts these three assumptions; after traumatic delivery/termination, hemorrhage, and its rarity. Thus, we attempted to clarify these three issues. METHODS: We retrospectively analyzed 22 UAP cases treated at our institute over a 6-year period. RESULTS: Uterine artery pseudoaneurysm occurred in 2-3/1,000 deliveries. Of 22 cases, half occurred after non-traumatic deliveries or non-traumatic pregnancy termination. Fifty-five percent (12/22) showed no hemorrhage; ultrasound or color Doppler revealed UAP. Thus, half of UAP occurred after non-traumatic deliveries or non-traumatic pregnancy termination and showed no hemorrhage at the time of their diagnoses. All patients received transarterial embolization, which stopped blood flow into UAP or achieved hemostasis. CONCLUSION: We must be aware that UAP may not be so rare and it may be present in patients after non-traumatic deliveries/pregnancy termination and without postpartum or postabortal hemorrhage.

[Use of surgical clips to verify positional accuracy in image-guided accelerated partial breast irradiation].

The purpose of this study was to evaluate the accuracy of positional verification during overall radiation treatment periods in accelerated partial breast irradiation using one or more surgical clips. We first investigated the appropriate computed tomography (CT) slice thickness and detectability of clips for a matching criterion in a phantom study. Next, clinical investigations were carried on 12 patients with multiple clips positioned around the lumpectomy cavity. During radiation treatment planning, a 5-mm region of interest (5-mm ROI) was defined by adding a three dimentional (3D) margin of 5 mm to each clip. During treatment, the clips on two orthogonal kilovoltage X-ray images acquired were moved so as to be included in the corresponding 5-mm ROI on digitally reconstructed radiographs (DRRs). Positional accuracy was calculated using the displacement of each clip in the verification images. The displacements of each clip acquired in all setups were then calculated throughout the overall radiation treatment period and the factors affecting the displacement of clips were investigated. Positional accuracy was also investigated in setups using skin marks and in setups using the bone structure around the thorax. We demonstrated in a phantom study that a CT slice thickness of 2.5 mm was appropriate. In our clinical investigations, 91% of the clips were included in the 5-mm ROI. The interfractional displacement of clips was large, with a long distance between the isocenter and each clip at the time of radiation treatment planning.

Efficacy of gonadal shielding in dose reduction for female pelvic radiography.

This study aimed to evaluate the dose reduction using gonad shielding (GS) during pelvic imaging. Three types of pelvic images (radiography, magnetic resonance and computed tomography) were fused to elucidate the three-dimensional relationship between the position of ovaries and GS. To estimate the dose received by the ovaries, the off-axis dose at any given depth was measured under two different imaging conditions using thermoluminescence dosemeters and a polymethyl methacrylate phantom. The mean ovarian depth was 8.4 cm. The mean estimated ovarian dose without an additional filter was 0.36 mGy without GS and 0.14 mGy with GS. The mean estimated ovarian dose with an additional filter was 0.24 mGy without GS and 0.10 mGy with GS. The efficacy of ovarian dose reduction should be evaluated based on the achieved ovarian dose, considering the ovarian depth and use of additional filtration, rather than the ovarian protection rate of GS.

Important surgical measures and techniques at cesarean hysterectomy for placenta previa accreta.

For cesarean hysterectomy with placenta previa accreta, "universally achievable" measures are required. We propose eight measures: (i) placement of intra-iliac arterial occlusion balloon catheters; (ii) placement of ureter stents; (iii) "holding the cervix" to identify the site to be transected; (iv) uterine fundal incision; (v) avoidance of uterotonics; (vi) "M cross double ligation" for ligating the ovarian ligament; (vii) "filling the bladder" to identify the bladder separation site and "opening the bladder" for placenta previa accreta with bladder invasion; and (viii) to continue to clamp the medial side of the parametrium or the cervix or employment of the "double edge pick-up" to ligate it. These eight measures are simple, easy, effective, and thus "universally achievable".

Adenomyomectomy, curettage, and then uterine artery pseudoaneurysm occupying the entire uterine cavity.

Uterine artery pseudoaneurysm can occur after cesarean section or traumatic delivery, usually manifesting as postpartum hemorrhage. Pregnant women after adenomyomectomy sometimes suffer some adverse events, among which uterine rupture has been widely acknowledged. We describe a post-abortive woman who had uterine artery pseudoaneurysm occupying the entire uterine cavity. She underwent adenomyomectomy and became pregnant. She experienced a missed abortion and underwent evacuation and curettage, which caused bleeding. Several days later, ultrasound revealed an intrauterine mass with marked blood flow. Angiography revealed the un-ruptured left uterine artery pseudoaneurysm, with arterial embolization stopping the flow within the pseudoaneurysm. Adenomyomectomy with subsequent curettage was considered to have caused the pseudoaneurysm. We must be cautious that pseudoaneurysm may occur in post-abortive women after adenomyomectomy.

Effects of interportal error on dose distribution in patients undergoing breath-holding intensity-modulated radiotherapy for pancreatic cancer: evaluation of a new treatment planning method.

In patients with pancreatic cancer, intensity-modulated radiotherapy (IMRT) under breath holding facilitates concentration of the radiation dose in the tumor, while sparing the neighboring organs at risk and minimizing interplay effects between movement of the multileaf collimator and motion of the internal structures. Although the breath-holding technique provides high interportal reproducibility of target position, dosimetric errors caused by interportal breath-holding positional error have not been reported. Here, we investigated the effects of interportal breath-holding positional errors on IMRT dose distribution by incorporating interportal positional error into the original treatment plan, using random numbers in ten patients treated for pancreatic cancer. We also developed a treatment planning technique that shortens breath-holding time without increasing dosimetric quality assurance workload. The key feature of our proposed method is performance of dose calculation using the same optimized fluence map as the original plan, after dose per fraction in the original plan was cut in half and the number of fractions was doubled. Results confirmed that interportal error had a negligible effect on dose distribution over multiple fractions. Variations in the homogeneity index and the dose delivered to 98%, 2%, and 50% of the volume for the planning target volume, and the dose delivered to 1 cc of the volume for the duodenum and stomach were ±1%, on average, in comparison with the original plan. The new treatment planning method decreased breath-holding time by 33%, and differences in dose-volume metrics between the original and the new treatment plans were within ± 1%. An additional advantage of our proposed method is that interportal errors can be better averaged out; thus, dose distribution in the proposed method may be closer to the planned dose distribution than with the original plans.

Assessing target localization accuracy across different soft-tissue matching protocols using end-exhalation breath-hold cone-beam computed tomography in patients with pancreatic cancer.

The purpose of this study was to retrospectively assess target localization accuracy across different soft-tissue matching protocols using cone-beam computed tomography (CBCT) in a large sample of patients with pancreatic cancer and to estimate the optimal margin size for each protocol. Fifty-four consecutive patients with pancreatic cancer who underwent 15-fraction volumetric modulated arc therapy under the end-exhalation breath-hold condition were enrolled. Two soft-tissue matching protocols were used according to the resectability classification, including gross tumor volume (GTV) matching for potentially resectable tumors and planning target volume (PTV) matching for borderline resectable or unresectable tumors. The tolerance of the target localization error in both matching protocols was set to 5 mm in any direction. The optimal margin size for each soft-tissue matching protocol was calculated from the systematic and random errors of the inter- and intrafraction positional variations using the van Herk formula. The inter- and intrafraction positional variations of PTV matching were smaller than those of GTV matching. The percentage of target localization errors exceeding 5 mm in the first CBCT scan of each fraction in the superior-inferior direction was 12.6 and 4.8% for GTV and PTV matching, respectively. The optimal margin sizes for GTV and PTV matching were 3.7 and 2.7, 5.4 and 4.1 and 3.9 and 3.0 mm in the anterior-posterior, superior-inferior and left-right directions, respectively. Target localization accuracy in PTV matching was higher than that in GTV matching. By setting the tolerance of the target localization error, treatment can be successful within the planned margin size.

Applicability evaluation of the TRS-483 protocol for the determination of small-field output factors using different multi-leaf collimator and field-shaping types.

PURPOSE: To evaluate the applicability of TRS-483 output correction factors (CFs) for small-field output factors (OFs) using different multi-leaf collimators (MLC) and field-shaping types. METHODS: All measurements were performed on TrueBeam, TrueBeam STx, and Halcyon using 6 MV flattening filter-free energy. Four detectors, including CC01, CC04, microDiamond, and EDGE, were used. Nominal field sizes ranging from 1 × 1 to 4 × 4, and 10 × 10 cm2 were used to measure small-field OFs at source-to-axis distance of 100 cm with a 0° gantry angle in a 3D water phantom. Further, the field-shaping types were defined using jaw collimator or MLC (five different configurations). A field size of 10 × 10 cm2 was used as the reference for calculation of OFs obtained as ratio of detector readings (OFdet). The percentage difference and coefficient of variation of OFdet and OFdet corrected by applying CF were compared for each field size and configuration. RESULTS: For OFdet corrected by applying CF, the ranges of percentage difference and coefficient of variation in all configurations for ≥ 2 × 2 cm2 fields were reduced from 1.2-2.2 to 0.8-1.3 percentage points (%pt) and from 0.5-1.0 to 0.4-0.7%, respectively. For 1 × 1 cm2 field, the ranges of percentage difference and coefficient of variation were reduced from 3.3-5.7 to 1.2-2.2 %pt and from 2.2-3.7 to 0.8-1.1%, respectively. CONCLUSIONS: The CFs described in TRS-483 dosimetry protocol have broad applicability in reducing OF variations between detectors under different MLC and field-shaping types.

New patient setup procedure using surface-guided imaging to reduce body touch and skin marks in whole-breast irradiation during the COVID-19 pandemic.

This study aimed to assess the effectiveness of a new patient-setup procedure using surface-guided imaging during the coronavirus disease 2019 (COVID-19) pandemic for left-sided whole-breast irradiation with deep inspiration breath-hold. Two setup procedures were compared regarding patient positioning accuracy for the first 22 patients. The first was a traditional setup (T-setup) procedure that used a surface-guided system after patient setup with traditional skin marks and lasers. The second procedure involved a new setup (N-setup) that used only a surface-guided system. The positioning accuracy of the remaining 23 patients was assessed using a setup that combined marker reduction and the N-setup procedure. No significant difference was observed in positioning accuracy between the two setups. The positioning accuracy of the marker-reduction setup was within 3 mm in all directions. The N-setup procedure may be a useful strategy for preventing infection during or after the COVID-19 pandemic.

Effect of angular dependence for small-field dosimetry using seven different detectors.

BACKGROUND: Small-field dosimetry is challenging for radiotherapy dosimetry because of the loss of lateral charged equilibrium, partial occlusion of the primary photon source by the collimating devices, perturbation effects caused by the detector materials and their design, and the detector size relative to the radiation field size, which leads to a volume averaging effect. Therefore, a suitable tool for small-field dosimetry requires high spatial resolution, tissue equivalence, angular independence, and energy and dose rate independence to achieve sufficient accuracy. Recently, with the increasing use of combinations of coplanar and non-coplanar beams for small-field dosimetry, there is a need to clarify angular dependence for dosimetry where the detector is oriented at various angles to the incident beam. However, the effect of angular dependence on small-field dosimetry with coplanar and non-coplanar beams has not been fully clarified. PURPOSE: This study clarified the effect of angular dependence on small-field dosimetry with coplanar and non-coplanar beams using various detectors. METHODS: Seven different detectors were used: CC01, RAZOR, RAZOR Nano, Pinpoint 3D, stereotactic field diode (SFD), microSilicon, and microDiamond. All measurements were taken using a TrueBeam STx with 6 MV and 10 MV flattening filter-free (FFF) energies using a water-equivalent spherical phantom with a source-to-axis distance of 100 cm. The detector was inserted in a perpendicular orientation, and the gantry was rotated at 15° increments from the incidence beam angle. A multi-leaf collimator (MLC) with four field sizes of 0.5 × 0.5, 1 × 1, 2 × 2, and 3 × 3 cm2 , and four couch angles from 0°, 30°, 60°, and 90° (coplanar and non-coplanar) were adopted. The angular dependence response (AR) was defined as the ratio of the detector response at a given irradiation gantry angle normalized to the detector response at 0°. The maximum AR differences were calculated between the maximum and minimum AR values for each detector, field size, energy, and couch angle. RESULTS: The maximum AR difference for the coplanar beam was within 3.3% for all conditions, excluding the maximum AR differences in 0.5 × 0.5 cm2 field for CC01 and RAZOR. The maximum AR difference for non-coplanar beams was within 2.5% for fields larger than 1 × 1 cm2 , excluding the maximum AR differences for RAZOR Nano, SFD, and microSilicon. The Pinpoint 3D demonstrated stable AR tendencies compared to other detectors. The maximum difference was within 2.0%, except for the 0.5 × 0.5 cm2 field and couch angle at 90°. The tendencies of AR values for each detector were similar when using different energies. CONCLUSION: This study clarified the inherent angular dependence of seven detectors that were suitable for small-field dosimetry. The Pinpoint 3D chamber had the smallest angular dependence of all detectors for the coplanar and non-coplanar beams. The findings of this study can contribute to the calculation of the AR correction factor, and it may be possible to adapt detectors with a large angular dependence on coplanar and non-coplanar beams. However, note that the gantry sag and detector-specific uncertainties increase as the field size decreases.

Impact of posttransplant portosystemic shunts on liver transplantation.

BACKGROUND: Posttransplant portosystemic shunts may result in severe fatty changes, portal vein complications, or graft liver failure because they reduce the effectiveness of portal perfusion through a portal steal phenomenon. However, the indications and timing of surgical and interventional treatments for posttransplant portosystemic shunts are still a matter of debate. We performed a retrospective investigation of the present state of long-term outpatients with posttransplant portosystemic shunts. METHODS: This study comprised 150 outpatients who underwent liver transplantation between October 1988 and August 2006 in our department and other facilities. The diagnosis was based on the presence of any portosystemic shunts with the diameter of more than 5 mm indicated by computed tomography. RESULTS: A total of 16 patients (16/150, 10.7 %) were diagnosed as having posttransplant portosystemic shunt. Among them, eight patients (8/16, 50.0 %) developed portal vein complications, and 1 (1/16, 6.3 %) developed graft liver failure. CONCLUSIONS: The persistence of posttransplant portosystemic shunts results in portal vein complications or graft liver failure. Therefore, surgical and interventional treatment for patients with posttransplant portosystemic shunts should be performed based on the clinical and radiologic findings.

[Verification of Effectiveness of Gonad Shielding in Female Hip Joint Radiography].

PURPOSE: It has been reported that the placement of protective equipment in female pelvic radiography is predominantly inadequate compared with that of male. We analyzed the actual situation of ovarian shielding by protective devices using X-ray, CT, and MR images obtained in the past, and evaluated the effectiveness of gonadal protection in female hip radiography. METHODS: The ovaries were contoured in MR images and the pelvic bone was extracted by CT images. The MR/CT fusion images were created using a 3D workstation. The amount of physiological fluctuation in the ovarian location was measured. The fusion images in the ray-summation display were manually superimposed with the X-ray image, and the percentage of ovaries that could be shielded by the protective device was classified into four categories: (a) complete protection, (b) partial protection, (c) failure of protection, and (d) image retaking. RESULTS: The mean and maximum ovarian fluctuations were 1.1 cm and 3.9 cm in the superior and inferior directions, respectively, and 0.7 cm and 2.0 cm in the left and right directions, respectively. The percentage of ovaries shielded was 18.9% for complete protection, 58.5% for partial protection, 15.1% for inadequate protection, and 7.5% for image retaking. CONCLUSION: The effectiveness of gonadal protection is low because the protective device could not cover the entire ovary in about 80% of the female hip radiographs.