Short communication: Positioning of temperature measurement points using multiplanar computed tomography

A method is described for the use of computed tomography and multiplanar reconstruction to depict in single images the full course of obliquely running thermometry catheters. In 14 patients given thermoradiotherapy for locally advanced breast carcinoma, reformatted images of the full catheter course were obtained for all 98 catheters so far tested. The main clinical advantage of this time-consuming procedure was the ability to determine the localization within the catheters of individual temperature measurement points of multipoint thermistor probes. It was also possible to study the localization of the measurement points in relation to the tumour margins.     

A simple method for the correction of distorted digital angiographic images for stereotactic target localization

The most commonly used imaging modality for the diagnosis and localization of arteriovenous malformations (AVMs) treated with stereotactic radiotherapy is traditional angiography, but it would be desirable to also use digital subtraction angiography (DSA). However, DSA images are distorted due to the electron-optical characteristics of the X-ray image intensifier. For that reason, we have developed a method for the correction of the image distortion. The ISIS II Treatment Planning System (ISIS II TPS), developed at the Curie Institute, has been used for image acquisition and stereotactic localization. A grid phantom has been constructed for determining the distortion of the DSA images. The software developed for the correction has been implemented into the TPS and is based on a correction vector produced by matching the distorted and corrected grid points. The method has been tested for its ability to correct the position of all grid points as well as its effectiveness in real cases as compared to traditional angiography. The maximum displacement of the corrected grid points compared with their original position is measured to be 0.1 mm. The accuracy of the target localization using the corrected DSA images is comparable with traditional angiography localization and falls inside acceptable accuracy limits. In conclusion, this method offers the possibility of using DSA images for stereotactic localization without limiting the requested accuracy.     

Interventional MRA: concepts for active visualization of catheters and stents

A precondition to safe guidance of vascular guidewires and catheters during the course of magnetic resonance (MR)-guided vascular intervention is a high-contrast visualization of the instruments. The integration of miniature radiofrequency (RF) coils and coaxial cables into guidewires and catheters enables the reception of RF signal from the lumen of blood vessels, and thus the active visualization of the instruments. Moreover, metallic vascular implants (stents) can be modified to act as intravascular RF antennas that inductively couple their RF signal to a conventional surface RF coil. Such stent resonators show signal amplification inside the lumen of the stent and thus can be visualized with high contrast in MR images. Furthermore, once such a device has been implanted, the method offers the potential for non-invasive long-term follow-up of the stent patency.     

Significant rectal and bladder dose reduction via utilization of Foley balloon catheters in high-dose-rate tandem and ovoid intracavitary brachytherapy of the uterine cervix

PURPOSE: To ascertain the potential for dose reduction to bladder and rectal points by using intravaginal Foley balloon catheters as a mechanism for structural displacement during tandem and ovoid high-dose-rate intracavitary brachytherapy of the uterine cervix. METHODS AND MATERIALS: In 22 patients, two Foley balloons were placed intravaginally, with one balloon placed anterior to the tandem and one posterior, as close to the flange as patient geometry allowed. A series of 57 consecutive digitized treatment plans was assessed with and without liquid contrast inflation of Foley catheter balloons. Planning X-rays were acquired and digitized. Software calculated dose was then defined for two bladder and two rectal points, both with and without Foley balloon inflation. Results were then assessed using parametric statistical analysis. RESULTS: Collectively and between equivalent points, a statistically significant (p < or = 0.01) diminution in calculated dose was observed with inflation of intracavitary balloon catheters, with a mean reduction in calculated dose of 16% and 17.6% for bladder and rectal points, respectively. CONCLUSION: The potential advantages available from dose reduction using intracavitary balloon catheters include decreased high-dose-rate-induced organ toxicity, case-by-case customizability, and low cost of implementation. As such, further exploration of this technique is warranted.     

Daily organ tracking in intensity-modulated radiotherapy of prostate cancer using an electronic portal imaging device with a dose saving acquisition mode.

BACKGROUND AND PURPOSE: Daily use of conventional electronic portal imaging devices (EPID) for organ tracking is limited due to the relatively high dose required for high quality image acquisition. We studied the use of a novel dose saving acquisition mode (RadMode) allowing to take images with one monitor unit per image in prostate cancer patients undergoing intensity-modulated radiotherapy (IMRT) and tracking of implanted fiducial gold markers. PATIENTS AND METHODS: Twenty five patients underwent implantation of three fiducial gold markers prior to the planning CT. Before each treatment of a course of 37 fractions, orthogonal localization images from the antero-posterior and from the lateral direction were acquired. Portal images of both the setup procedure and the five IMRT treatment beams were analyzed. RESULTS: On average, four localization images were needed for a correct patient setup, resulting in four monitor units extra dose per fraction. The mean extra dose delivered to the patient was thereby increased by 1.2%. The procedure was precise enough to reduce the mean displacements prior to treatment to < o =0.3 mm. CONCLUSIONS: The use of a new dose saving acquisition mode enables to perform daily EPID-based prostate tracking with a cumulative extra dose of below 1 Gy. This concept is efficiently used in IMRT-treated patients, where separation of setup beams from treatment beams is mandatory.     

Marker seed migration in prostate localization

PURPOSE: Marker seed location was analyzed to test the hypothesis that there is no intraseed migration within the prostate, a premise fundamental to the technique of marker seed localization of this organ. Despite increasing interest in the use of implanted seeds as fiducial markers for gland location, there are few data available with which to evaluate the validity of this technique, particularly over the entire course of external beam radiation therapy. METHODS AND MATERIALS: Between May 2001 and December 2001, after obtaining fully informed written consent, 9 patients with early stage prostate cancer were enrolled on an institutionally reviewed protocol. Patients had four to five marker seeds implanted into the prostate under transrectal ultrasound guidance before definitive radiotherapy. The porous gold seeds were each 1.2 x 2.0 mm in dimension. Seed locations from orthogonal radiographs based on the initial simulation and weekly orthogonal films were digitized using a CMS Focus planning system, thereby facilitating the determination of intraseed spacing. The digitization of the isocenter from each orthogonal pair of radiographs was used to determine digitizing error for seed localization. Pubic symphysis, bilateral femoral heads, and isocenter were also digitized and will be analyzed at a later date. RESULTS: Overall, the average migration of all the seeds in the patients was 1.2 +/- 0.2 (SD) mm. The greatest average movement of any seed in any patient was 1.9 mm over the entire 7-week course of radiotherapy. The smallest average movement was 0.6 mm. The greatest change in intraseed spacing in any of the patients during the full course of therapy was 6.6 mm. One seed in 1 patient was lost at the start of the third week of therapy and censored from analysis. Digitizing error in seed localization was calculated to be 0.20 +/- 0.03 (SD) mm. CONCLUSIONS: As an aggregate, there is negligible seed migration within the prostate over the entire course of definitive radiotherapy. However, there are small, detectable movements in individual seed locations, perhaps resulting from topographic changes in the gland secondary to seed placement, anatomic changes in bladder and rectum, or treatment itself. With respect to seed migration, prostate marker seeds represent an accurate and reliable surrogate of gland location during a full course of radiotherapy.     

Accuracy and conformity of stereotactically guided interstitial brain tumour therapy using I-125 seeds.

OBJECTIVE: To assess the accuracy of the stereotactic implantation procedure of catheters containing I-125 seeds in brain tumours and investigate the effect of catheter deviations on the dose distribution in patients. METHODS: A randomised sample (n = 37) of all patients treated with I-125 seeds in our department between 6/1994 and 2/2002 was examined. Intraoperative X-ray images were used to measure deviations of implanted I-125 seed catheters from their planned positions and the influence on dose conformity, tumour surface dose and dose burden of surrounding healthy brain tissue was determined. RESULTS: The mean spatial target point deviation was 2.0 mm (maximum 4.1 mm, SD 0.9 mm) and in 54.1% of the cases, reduction of the planned dose was greater than 5%. Target point deviations less than 1.5 mm have only minor influence on surface dose and conformity. Results indicated that in 10.8% of the cases the realized dose distribution showed a 'slight deviation', according to the guideline criteria for external radiosurgery of the Radiation Therapy Oncology Group. In 89.2% of the patients the applied dose conformed to the target volume. CONCLUSIONS: Stereotactically guided interstitial irradiation with I-125 seeds can be used to treat brain tumours and metastases with high conformity comparable to radiosurgery. The observed deviations of the stereotactically implanted I-125 seed catheters from their planned target points were smaller when compared to frameless procedures. In order to maintain the required spatial accuracy of 1.5 mm in interstitial therapy using I-125 seeds, it appears necessary to optimise stereotactic instruments further.     

Long-term silicone central venous catheters impregnated with minocycline and rifampin decrease rates of catheter-related bloodstream infection in cancer patients: a prospective randomized clinical trial.

PURPOSE: To evaluate the efficacy of long-term nontunneled silicone catheters impregnated with minocycline and rifampin (M-R) in reducing catheter-related bloodstream infections. PATIENTS AND METHODS: This prospective, randomized, double-blind clinical trial was conducted at M.D. Anderson Cancer Center, a tertiary care hospital in Houston, TX. All patients in the trial had a malignancy. RESULTS: Between September 1999 and May 2002, 356 assessable catheters were used: 182 M-R and 174 nonimpregnated. The patients' characteristics were comparable between the two study groups. The mean (+/- standard deviation) duration of catheterization with M-R catheters was comparable to that of nonimpregnated catheters (66.21 +/- 30.88 v 63.01 +/- 30.80 days). A total of 17 catheter-related bloodstream infections occurred during the course of the study. Three were associated with the use of M-R catheters and 14 were associated with the nonimpregnated catheters, with a rate of catheter-related bloodstream infection of 0.25 and 1.28/1,000 catheter-days, respectively (P = .003). Gram-positive cocci accounted for the majority of the organisms causing the infections. There were no allergic reactions associated with M-R catheters. CONCLUSION: Long-term nontunneled central venous catheters impregnated with minocycline and rifampin are efficacious and safe in reducing catheter-related bloodstream infections in cancer patients.     

Percutaneous placement of two single-lumen Silastic catheters for long-term venous access. Lessons learned with experience in over 200 patients

A simple, fast technique for percutaneous insertion of two single-lumen, large-bore Silastic catheters for long-term venous access is described. Helpful technical points are discussed. Recent experience with insertion of 102 catheters using this technique yielded no major complications.     

Obstructed central venous catheters. Restoring function with a 12-hour infusion of low-dose urokinase

Thrombotic obstruction frequently prohibits infusion through or withdrawal of blood from central venous catheters and can occur in conjunction with symptomatic thrombosis of the subclavian vein. Thirty catheters were radiographically proved to be obstructed by thrombus and had not responded to at least one instillation of 5000 units of urokinase. All catheters were treated with a 12-hour infusion of urokinase at the rate of 40,000 units/hour. The obstructing thrombus was either eliminated or reduced in size in all instances and full function was restored in all but one catheter. No bleeding complications were seen. Six patients with obstructed catheters also had symptoms of subclavian vein thrombosis. All patients with symptoms of subclavian vein obstruction became asymptomatic on anticoagulant therapy even though no attempt at dissolving the thrombus obstructing the subclavian vein was made. A 12-hour infusion of low doses of urokinase can safely salvage function of obstructed catheters that otherwise may require replacement. Patients with concomitant subclavian vein thrombosis become asymptomatic on anticoagulant therapy without need to dissolve the obstructing thrombus.     

术中胸腔内胸壁定位法在肺结节术中的应用体会

背景与目的：探讨一种简单、安全、准确、无创的肺结节术中定位方法,以供更多的术者参考,惠及更多的肺结节患者。方法：收集100例在浙江省舟山医院胸心外科行亚肺叶切除术的肺小结节患者。结合术前CT影像,测定肺结节在胸壁内侧壁层胸膜上的定位点后,电凝钩留置在此点上,嘱麻醉师充分鼓肺后屏气,电凝钩在肺表面留下烧灼点,为肺小结节在胸膜表面的定位点。切下标本后,测量肺表面定位烧灼点与结节之间距离、结节与切缘距离数据,来评价定位准确性。结果：定位准确率达99.1%,其中仅有1例患者肺小结节与定位点有明显偏差（>1.5 cm）,二次切割后找到肺结节,其余患者均为一次性切除成功,手术成功率为100.0%,无并发症发生。结论：术中胸腔内胸壁定位法无创、简便、安全,无并发症发生,尤其对特殊部位肺结节能较准确定位,有明显的优势,值得推广。     

Technetium-99m-labeled macroaggregated albumin arteriography for detection of abnormally positioned arterial catheters during infusion chemotherapy

The arterial catheter position of 500 courses of intra-arterial chemotherapy were monitored by intraarterially introduced Technetium-99m macroaggregated albumin (MAA) particles. Seventeen instances of abnormally positioned catheters (3.4%) were detected by MAA arterial perfusion (MAAAP). All these abnormally positioned catheters were subsequently repositioned resulting in improved tumor perfusion. Plain radiographs obtained in eight instances failed to reveal the abnormally positioned catheter in four, while all eight of these abnormally positioned catheters were detected by MAAAP. Abnormally positioned catheters detected by MAAAP were either immediately after arterial catheter placement (nine instances) or during the course of chemotherapy (eight instances). Of the right instances of displaced catheters during intra-arterial chemotherapy, six instances were accompanied by clinical signs and symptoms suggestive of displaced catheter. Arteriovenous shunting was documented in 5 of 12 hepatic MAAAP studies as evidenced by increased lung activity. When the catheters were displaced in these cases, the lung activity changed: completely disappearing in two instances; decreasing in two instances and remaining unchanged in one.     

Cone-beam CT localization of internal target volumes for stereotactic body radiotherapy of lung lesions

PURPOSE: In this study, we investigate a technique of matching internal target volumes (ITVs) in four-dimensional (4D) simulation computed tomography (CT) to the composite target volume in free-breathing on-board cone-beam (CB) CT. The technique is illustrated by using both phantom and patient cases. METHODS AND MATERIALS: A dynamic phantom with a target ball simulating respiratory motion with various amplitude and cycle times was used to verify localization accuracy. The dynamic phantom was scanned using simulation CT with a phase-based retrospective sorting technique. The ITV was then determined based on 10 sets of sorted images. The size and epicenter of the ITV identified from 4D simulation CT images and the composite target volume identified from on-board CBCT images were compared to assess localization accuracy. Similarly, for two clinical cases of patients with lung cancer, ITVs defined from 4D simulation CT images and CBCT images were compared. RESULTS: For the phantom, localization accuracy between the ITV in 4D simulation CT and the composite target volume in CBCT was within 1 mm, and ITV was within 8.7%. For patient cases, ITVs on simulation CT and CBCT were within 8.0%. CONCLUSION: This study shows that CBCT is a useful tool to localize ITV for targets affected by respiratory motion. Verification of the ITV from 4D simulation CT using on-board free-breathing CBCT is feasible for the target localization of lung tumors.     

The importance of postoperative CT image fusion verification of stereotactic interstitial irradiation for brain tumors

PURPOSE: The aim of our study was verification of the position of implanted catheters with (125)I seeds after the catheter implantation for the brachytherapy of brain tumors. METHODS AND MATERIALS: The fusion of the CT image used at planning and after the implantation of the catheters enabled us to verify the position of the catheters containing the isotopes. After this, the tumor volume covered by the prescribed dose (TV(PD)) and the normal tissue volume covered by the prescribed dose (NTV(PD)) were compared between the plan and the actual result. The image fusion was performed by the BrainLab-Target 1.19 software on an Alfa 430 (Digital) workstation. RESULTS: The position of the catheters was adjusted in 14 (20%) of the 70 image fusion cases being studied. The position of 16 of the 116 catheters (13.8%) required adjustment after the fusion of control images in the 70 cases studied. The Student t probe revealed a significant difference between the TV(PD) values of the reality and the plans (75.8% vs. 92.4%, p < 0.0001). There was a significant difference between values of the real performances and planning for NTV(PD) (86.8% vs. 76%, p = 0.001) and for the conformity index (0.37 vs. 0.54, p = 0.0001), too. CONCLUSION: The application of the interstitial irradiation with CT control allows us to identify and correct possible inaccuracies in catheter positioning during the operation. The procedure then becomes far more accurate and reliable, and as such, the irradiation becomes more conformal than without catheter adjustment.     

未扪及肿块的乳腺癌病灶定位与手术方法

目的 探讨仅影像学表现为恶性钙化而乳房未扪及肿块乳腺癌的病灶定位方法、手术方法及其治疗效果.方法 对61例乳房体检不能触及肿块、影像学检查也未发现肿块,仅X线钼靶片或超声检查显示恶性钙化病灶或局部血流丰富的乳腺癌(T1～2NOM0)患者,术前应用全数字化平板乳腺机(FFDM),对钙化病灶进行坐标法立体定位、术中精确切除病灶、术后应用FFDM法复检标本,同时行广基带血管腺体组织瓣Ⅰ期乳房内成形保乳手术(单发病灶者)或乳腺癌改良根治术(多中心病灶者).结果 50例行保乳手术的患者,坐标法定位病灶的准确率为100%(50/50).对病灶切缘阴性、FFDM复检无病灶残留者,其广基带血管腺体组织瓣乳腺Ⅰ期成形结果按JCRT标准,达优率为86.0%(43/50);Compliance差值为1.5 cm.11例行乳腺癌改良根治术,均为外弥漫性恶性钙化多中心病灶者.61例患者的随访时间为6～58个月(中位随访时间为39个月).全组仅1例远处转移,无局部复发患者.结论 对不能扪及肿块的乳腺癌病灶,应用FFDM坐标法定位,准确可行.对单发病灶者,在定位下行保乳手术,同时行广基带血管腺体组织瓣Ⅰ期乳房内成形术,疗效满意.     

Use of a totally implantable drug delivery system in a university-affiliated community hospital

We reviewed our experience at the Western Reserve Care System with totally implantable drug delivery systems (IDDS) in cancer patients with vascular access problems. Fifty-one ports were placed in 50 patients. Forty-nine of the IDDS were placed under local anesthesia. One patient developed a hemothorax during placement. Two catheters were removed because of infection. Two catheters found to be occluded responded to flushing with streptokinase. All catheters remained functional up to the time of treatment completion or of the patient's death. The low morbidity and high success rates of IDDS should encourage placement early in the course of chemotherapy.     

Prophylactic urokinase in the management of long-term venous access devices in children: a Children's Oncology Group study.

PURPOSE: Infection and thrombosis are serious complications of long-term vascular access devices in children undergoing chemotherapy. Since routine fibrinolytic therapy may decrease these complications, the purpose of this study was to compare the efficacy of an every-2-week administration of urokinase with standard heparin flushes in reducing the incidence of device-related infections and occlusions. MATERIALS AND METHODS: This study was a prospective, randomized phase III multicenter trial conducted by the Children's Cancer Group, in which patients with implantable ports or tunneled catheters received either urokinase or heparin every 2 weeks for 12 months. Study end points were time to first occlusion or time to first device-related infection. RESULTS: Five hundred seventy-seven patients from 29 institutions were enrolled, of whom 51% had external catheters and 49% had ports. Urokinase administration resulted in fewer occlusive events than heparin (23% v 31%; P =.02), a longer time to first occlusive event (log-rank analysis, P =.006), and a 1.6-fold difference in the rate of occlusive events (Poisson regression, P =.003). Similar results were noted when comparing ports and tunneled catheters. The urokinase group also had a 1.4-fold difference in the rate of infection (Poisson regression, P =.05) and longer time to first infection (log-rank, P =.07), but the difference was significant only in tunneled catheters. CONCLUSION: Urokinase administration every 2 weeks significantly affects the rate of occlusive events in ports and tunneled catheters and of infectious events in external catheters compared with heparin administration.     

Impact of probe pressure variability on prostate localization for ultrasound-based image-guided radiotherapy

Purpose

To evaluate the impact of transabdominal probe pressure on prostate positioning with an intramodality ultrasound (US) image-guided-radiotherapy system and to quantify pressure variability over the treatment course.

Material and methods

8 prostate cancer patients (group A) and 17 healthy volunteers underwent 3 consecutive US images with increasing probe pressure levels, and 1 CT acquisition for the group A only. Prostate positions were compared after manual registration of the first US image contour projected on 2 others. Group A’s pressure levels were quantified by measuring skin-to-skin distances between corresponding CT–US images. The same methodology was used on paired CT/CBCT–US images acquired during treatments of 18 prostate cancer patients to determine whether the different pressure levels applied to the group A were close to the clinical practices and to quantify pressure variability along the treatment course.

Results

84% of 3D prostate displacements were above 2 mm for at least one pressure level. Probe pressures deliberately applied were similar to the ones observed clinically. The latter drastically varied between sessions.

Conclusion

Even with an intramodality system, probe pressure can impact prostate localization because of the pressure variability along the treatment course. Therefore, margins should be expanded from 0.5 to 1.2 mm to ensure treatment accuracy.