Prospective Treatment Planning Research Articles

NTCP Modeling of Patient Reported Xerostomia after De-Intensified Chemoradiotherapy for HPV Associated Oropharynx Cancer

Patients with head & neck tumors are commonly treated with external radiation therapy. Due to the proximity of the parotids to the tumor they often receive high doses to a portion of their volume. We prospectively enrolled patients on an IRB-approved clinical trial to estimate the correlation between different normal tissue complication probability (NTCP) models and dosimetric indices of the parotid and submandibular glands with the patient reported severity of xerostomia 12 months post de-intensified chemoradiotherapy. 120 patients with favorable risk, HPV-associated oropharyngeal squamous cell carcinoma were treated with de-intensified chemoradiotherapy. 60Gy delivered with intensity modulated radiotherapy was prescribed to all patients, who also received concurrent weekly intravenous cancer-treating drugs (30 mg/m2). The dose constraints for contralateral parotid and submandibular glands were mean dose <26 and <35, respectively. The status of xerostomia was reported pre- and post-treatment using the patient reported outcome version of the CTCAE (PRO-CTCAE): none/mild/moderate/severe/very severe. We correlated individual patient dosimetric data from the contralateral parotid and contralateral glands (parotid and submandibular glands combined) with the changes in the severity of xerostomia at 12 month post-treatment. A change in severity (from baseline) of ≥ 2 was considered clinically meaningful. The clinical data were fitted by the Lyman-Kutcher-Burman (LKB) and Relative Seriality (RS) NTCP models. Xerostomia increased in 40 patients (33%). Median mean doses to the contralateral parotid and combined glands were 23Gy (range: 5.1-47.1Gy) and 28Gy (range: 6-50Gy), respectively. For both structures, the V15Gy and mean doses correlated best with the subsequent xerostomia (AUC = 0.68-0.70). The values for the D50, m and n parameters of the Lyman-Kutcher-Burman model are 67Gy, 0.58 and 0.01 for the contralateral parotid and 56Gy, 0.56 and 0.12 for the combined glands. The values for the D50, γ and s parameters of the Relative Seriality model are 31.0Gy, 0.46 and 1.0 for the contralateral parotid and 39Gy, 0.48 and 1.0 for the combined glands. The AUC values for the two NTCP models for the contralateral parotid and combined glands and were similar 0.65 and 0.64, respectively. A statistically significant Odds Ratio of 5.7 (95%CI: 2.0-16.1Gy) was found for the contralateral parotid at V15Gy ≤ 53% and 7.8 (95%CI: 2.2-27.5Gy) for the combined glands at V15Gy ≤ 61%. The dosimetric thresholds V15Gy ≤ 53% to the contralateral parotid and V15Gy ≤ 61% to the combined parotid and submandibular glands were found to significantly reduce the risk for xerostomia. The dose-response curve of xerostomia could be determined by fitting the clinical data with the LKB and RS NTCP models. These models can provide constraints, which can be very useful in prospective treatment plan optimization and evaluation.

NTCP Modeling of Xerostomia Related to Parotid Dose from Whole-Brain Radiation Therapy

We recently reported an association between parotid dose and xerostomia in patients receiving whole brain radiation therapy (WBRT). The purpose of this analysis is to perform normal tissue complication probability (NTCP) modeling to further explore the parotid dosimetric indices associated with patient-reported xerostomia. Patients receiving WBRT (25-40 Gy in 10-20 fractions) for any diagnosis were enrolled on a prospective observational study. WBRT was delivered with 3D-conformal radiation therapy using standard opposed lateral fields covering C1. The parotids were not prospectively delineated, but retrospectively delineated and considered one structure for analysis. Patients completed the University of Michigan Xerostomia Questionnaire (Xerostomia score, scaled 0-100, higher is worse) and a 4-point dry mouth “bother” score (1-Not at all, 2-A little, 3-Quite a bit, 4-Very much) at baseline, conclusion of WBRT, 2 weeks, 1 month (primary endpoint), 3 months, and 6 months post-WBRT. The clinical data were fitted by the Lyman-Kutcher-Burman (LKB) and Relative Seriality (RS) NTCP models using outcomes at 1 month post-RT. We defined toxicity as a ≥20 point worsening in xerostomia score, or a ≥2 point worsening in bother score. 55 patients who reached the primary time point of 1 month were eligible for analysis. Median WBRT dose was 30 Gy in 10 fractions. Median parotid mean dose was 17Gy (Range, 11-28Gy) and median parotid V20Gy was 48% (Range, 24-84%). Xerostomia score increased by ≥20 in 19 patients (35%), and bother score increased by ≥2 points in 11 patients (20%). Parotid V5Gy-V20Gy were found to correlate best with toxicity, with AUC 0.68 for xerostomia score and 0.69 to 0.71 for bother score. AUC values for parotid mean dose were 0.64 and 0.65 for xerostomia score and bother score respectively. The values for the D50, m and n parameters of the Lyman-Kutcher-Burman model were 22.3Gy, 0.84 and 1.0, respectively for xerostomia score and 28.4Gy, 0.55 and 1.0 for bother score. Similarly, the values for the D50, γ and s parameters of the Relative Seriality model were 23.5Gy, 0.28 and 0.0001, respectively for xerostomia score and 32.0Gy, 0.45 and 0.0001 for bother score. A statistically significant toxicity Odds Ratio of 8.6 and 9.1 was observed in patients with parotid V20Gy > 48% for xerostomia score and bother score, respectively. Clinically significant xerostomia was fairly common after WBRT and correlated well with parotid V5Gy-V20Gy. The dose-response for xerostomia could be determined by fitting the clinical data with the LKB and RS NTCP models. These data support the need for minimization of parotid dose in patients receiving WBRT. Additionally, they can be very useful in prospective treatment plan optimization and evaluation.

Correlation between preoperative endoscopic ultrasound and surgical pathology staging of gastric adenocarcinoma: A single institution retrospective review.

Recent evidence validates the effectiveness of neoadjuvant chemotherapy in the treatment of gastric adenocarcinoma. Endoscopic ultrasonographic (EUS) staging has been proposed as a useful adjunct in this setting. We performed a retrospective review of patients treated at our institution for gastric adenocarcinoma between July 2005 and January 2014. We identified patients referred for EUS before surgery as part of a prospective treatment plan. Histopathologic staging was compared to EUS staging, with a focus on T- and N-stage. Agreement between the two modalities was examined using kappa-statistics. We identified 614 patients with biopsy-proven gastric adenocarcinoma; 145 underwent curative-intent surgery. Surgical pathology and EUS results were available from 69 patients. The accuracy of EUS for the evaluation of T- and N-stage was 44.9% and 56.5%, respectively. EUS demonstrated greater concordance with histopathology at evaluating T-stage (κ = 0.3469) than N-stage (κ = 0.1316). EUS underestimated T- and N-stage in 40.8% and 30.4% of patients, respectively. EUS seems to correlate poorly with pathology in the preoperative staging of gastric adenocarcinoma. In the majority of inaccurate cases, EUS underestimates T-stage and N-stage, limiting its utility in the neoadjuvant setting.

Tumor and red bone marrow dosimetry: comparison of methods for prospective treatment planning in pretargeted radioimmunotherapy.

BackgroundRed bone marrow (RBM) toxicity is dose-limiting in (pretargeted) radioimmunotherapy (RIT). Previous blood-based and two-dimensional (2D) image-based methods have failed to show a clear dose-response relationship. We developed a three-dimensional (3D) image-based RBM dosimetry approach using the Monte Carlo-based 3D radiobiological dosimetry (3D-RD) software and determined its additional value for predicting RBM toxicity.MethodsRBM doses were calculated for 13 colorectal cancer patients after pretargeted RIT with the two-step administration of an anti-CEA × anti-HSG bispecific monoclonal antibody and a 177Lu-labeled di-HSG-peptide. 3D-RD RBM dosimetry was based on the lumbar vertebrae, delineated on single photon emission computed tomography (SPECT) scans acquired directly, 3, 24, and 72 h after 177Lu administration. RBM doses were correlated to hematologic effects, according to NCI-CTC v3 and compared with conventional 2D cranium-based and blood-based dosimetry results. Tumor doses were calculated with 3D-RD, which has not been possible with 2D dosimetry. Tumor-to-RBM dose ratios were calculated and compared for 177Lu-based pretargeted RIT and simulated pretargeted RIT with 90Y.Results3D-RD RBM doses of all seven patients who developed thrombocytopenia were higher (range 0.43 to 0.97 Gy) than that of the six patients without thrombocytopenia (range 0.12 to 0.39 Gy), except in one patient (0.47 Gy) without thrombocytopenia but with grade 2 leucopenia. Blood and 2D image-based RBM doses for patients with grade 1 to 2 thrombocytopenia were in the same range as in patients without thrombocytopenia (0.14 to 0.29 and 0.11 to 0.26 Gy, respectively). Blood-based RBM doses for two grade 3 to 4 patients were higher (0.66 and 0.51 Gy, respectively) than the others, and the cranium-based dose of only the grade 4 patient was higher (0.34 Gy). Tumor-to-RBM dose ratios would increase by 25% on average when treating with 90Y instead of 177Lu.Conclusions3D dosimetry identifies patients at risk of developing any grade of RBM toxicity more accurately than blood- or 2D image-based methods. It has the added value to enable calculation of tumor-to-RBM dose ratios.

Multidisciplinary Breast Conference Improves Patient Management and Treatment

Introduction: Multidisciplinary breast conference (BC) that discusses different clinicopathological aspects of disease creates a sound, complete and unique treatment plan for each patient. The aim of this study was to investigate the role of weekly breast tumor boards in patient management and treatment modifications. Methods: From June 2010 to June 2011, 242 patients (Stage 0 to Stage 4 breast cancer) were prospectively presented before a multidisciplinary team. Presentation included clinical data, imaging and pathological review followed by prospective treatment plan formulated by the physician group. If postoperative presentation, final histopathology of the tumor and adjuvant treatment relevant to each patient was discussed. Breast conference was performed via teleconference, including video projection of pathology slides and images. Feedback evaluations were completed and returned to the Tumor Registry for consistent weekly improvement of BC. Results: 102 patients (42%) had modified management after being presented at BC, 38% (n = 39) surgical, 33% (n = 34) medical (chemotherapy/endocrine therapy), 17% (n = 17) radiation, 6% (n = 6) both medical and radiation treatment and 6% (n = 6) imaging changes. Majority of changes were made to patients with Stage IA (27%) followed by Stage 0 (21%) breast cancer. Conclusion: Breast conference presents a significant impact on patient management and serves as a model for best practice in cancer care. Consultative discussion of each case permits every team member to be acutely aware of the patient’s condition, contribute to treatment plan and permit a harmonious and cooperative team approach while assuring best treatment for the patient.

SU‐E‐T‐162: Prospective Treatment Plan Modeling To Guide Patient‐Specific Treatment Setups for Hypofractionated Intracranial and Spinal Radiosurgery

Purpose: Residual patient setup shifts such as 1 mm or 1 degree are commonly observed during online treatment setups of hypofractionated radiosurgery (HRS) of spine and intracranial lesions. To effectively guide patient‐specific setups, a prospective treatment planning approach was developed for such treatments. Methods: For a cohort of intracranial and spinal HRS treatments, individualized setup guidelines were prospectively determined via the following approach: (1) systematically shift and rotate 3D patient image data in incremental small steps. (2) For each step such as 0.1 mm or 0.1 degree, dose distributions from original treatment plan were recalculated. (3) Each resulting dose distributions were then iteratively checked against a set of preset dosimetric criteria for compliance. (4) From step 3, maximum tolerable shift levels along the major axes were then determined. Finally, we tested such an approached on a cohort of treatment cases performed at our institutions. Results: For studied treatment sessions (n=63), the mean maximum tolerable shift levels including rotations projected unto the major axes were determined to be 2.0±0.7mm, 2.1±0.9 mm and 1.9±0.8 mm along the lateral, longitudinal, and vertical axis, respectively. Such tolerance levels were significantly (p=0.02) larger than the machine preset tolerance level of 1.0 mm that commonly enforced for all treatment sessions. However, more than 50% of the treatment sessions exhibited sub‐millimeter tolerance level along certain directions to meet critical structure constraints. For example, a 0.6‐mm anterior maximum shift could incur 36% increase in the maximum dose to the brainstem for one patient case. Conclusion: Patient specific online setup guidelines for HRS has been demonstrated to prevent potential deleterious effects from residual shifts while facilitating online setups by providing more room of larger acceptable shifts for a majority of treatment cases.

Magnetic resonance temperature imaging validation of a bioheat transfer model for laser‐induced thermal therapy

Purpose: Magnetic resonance‐guided laser‐induced thermal therapy (MRgLITT) is currently undergoing initial safety and feasibility clinical studies for the treatment of intracranial lesions in humans. As studies progress towards evaluation of treatment efficacy, predictive computational models may play an important role for prospective 3D treatment planning. The current work critically evaluates a computational model of laser induced bioheat transfer against retrospective multiplanar MR thermal imaging (MRTI) in a canine model of the MRgLITT procedure in the brain.Methods: A 3D finite element model of the bioheat transfer that couples Pennes equation to a diffusion theory approximation of light transport in tissue is used. The laser source is modelled conformal with the applicator geometry. Dirichlet boundary conditions are used to model the temperature of the actively cooled catheter. The MRgLITT procedure was performed on n = 4 canines using a 1‐cm diffusing tip 15‐W diode laser (980 nm). A weighted norm is used as the metric of comparison between the spatiotemporal MR‐derived temperature estimates and model prediction.Results: The normalised error history between the computational models and MRTI was within 1–4 standard deviations of MRTI noise. Active cooling models indicate that the applicator temperature has a strong effect on the maximum temperature reached, but does not significantly decrease the tissue temperature away from the active tip.Conclusions: Results demonstrate the computational model of the bioheat transfer may provide a reasonable approximation of the laser–tissue interaction, which could be useful for treatment planning, but cannot readily replace MR temperature imaging in a complex environment such as the brain.

High-fidelity Computer Models for Prospective Treatment Planning of Radiofrequency Ablation with In Vitro Experimental Correlation

To evaluate the accuracy of computer simulation in predicting the thermal damage region produced by a radiofrequency (RF) ablation procedure in an in vitro perfused bovine liver model. The thermal dose end point in the liver model is used to assess quantitatively computer prediction for use in prospective treatment planning of RF ablation procedures. Geometric details of the tri-cooled tip electrode were modeled. The resistive heating of a pulsed voltage delivery was simulated in four dimensions using finite element models (FEM) implemented on high-performance parallel computing architectures. A range of physically realistic blood perfusion parameters, 3.6-53.6 kg/sec/m(3), was considered in the computer model. An Arrhenius damage model was used to predict the thermal dose. Dice similarity coefficients (DSC) were the metric of comparison between computational predictions and T1-weighted contrast-enhanced images of the damage obtained from a RF procedure performed on an in vitro perfused bovine liver model. For a perfusion parameter greater than 16.3 kg/sec/m(3), simulations predict the temporal evolution of the damaged volume is perfusion limited and will reach a maximum value. Over a range of physically meaningful perfusion values, 16.3-33.1 kg/sec/m(3), the predicted thermal dose reaches the maximum damage volume within 2 minutes of the delivery and is in good agreement (DSC > 0.7) with experimental measurements obtained from the perfused liver model. As measured by the computed volumetric DSC, computer prediction accuracy of the thermal dose shows good correlation with ablation lesions measured in vitro in perfused bovine liver models over a range of physically realistic perfusion values.

Tumor Board: More Than Treatment Planning—A 1-Year Prospective Survey

The aim of this study was to evaluate the impact of gynecologic oncology tumor boards (TBs) on patient care and graduate education. Sequential TBs were prospectively recorded. Case presentations preceded review of diagnostic studies and pathology. Following consultative dialogue, treatment plans were synthesized. Disposition alterations were categorized as major, minor, or none. In 52 weekly TBs, 153 patients were presented. Alterations were made in 53 cases. Major alterations (n = 13) predominantly resulted from pathology reassignments. Minor alterations (n = 40) resulted from pathology, staging, radiology, and surgical team clarifications. Multidisciplinary TBs provide important information for prospective treatment planning and a significant educational opportunity for postgraduate trainees.

RF hyperthermia array modelling; validation by means of measured EM-field distributions

The accuracy of a hyperthermia treatment simulation determines its role in prospective treatment planning and dosimetry for the individual patient. Of importance are (1) the accuracy of the numerical simulation method, and (2) the numerical description of the hyperthermia treatment system. The accuracy of the numerical method is generally determined by analysis of a problem that is analytically solvable. The validity of the description of the hyperthermia system is to be investigated by comparison of the simulated and measured EM-field amplitude and phase of the clinical operational hyperthermia system. In this paper, the numerical description of the AMC-4 waveguide phased array for which treatment planning is performed by the Weak Form of the Conjugate Gradient FFT method is investigated. The accuracy of the description is analysed for four setups, varying the bolus size and the number of waveguides attached to a phantom. The comparison of experimental and numerical data has demonstrated the ability of the Weak Formulation of the Conjugate Gradient FFT method to predict the EM-field of the AMC-4 waveguide array hyperthermia system, including effects due to bolus size variations. However, based on the comparison of the measured EM-field distributions and those obtained from simulations, the accuracy of the planning system is found to be insufficient for quantitative SAR dosimetry for individual patients. Qualitative SAR dosimetry can be applied in cases where the accuracy is of minor importance, e.g. for the retrospective analysis of problematic hyperthermia treatments. Prospective applications of the treatment planning system include the (qualitative) determination/simulation of a set of starting points giving a 'close to optimal' amplitude and phase setting, the prediction of possible problem areas and the analysis of the performance of new/improved hyperthermia devices.

RF hyperthermia array modelling; validation by means of measured EM-field distributions.

The accuracy of a hyperthermia treatment simulation determines its role in prospective treatment planning and dosimetry for the individual patient. Of importance are (1) the accuracy of the numerical simulation method, and (2) the numerical description of the hyperthermia treatment system. The accuracy of the numerical method is generally determined by analysis of a problem that is analytically solvable. The validity of the description of the hyperthermia system is to be investigated by comparison of the simulated and measured EM-field amplitude and phase of the clinical operational hyperthermia system. In this paper, the numerical description of the AMC-4 waveguide phased array for which treatment planning is performed by the Weak Form of the Conjugate Gradient FFT method is investigated. The accuracy of the description is analysed for four set-ups, varying the bolus size and the number of waveguides attached to a phantom. The comparison of experimental and numerical data has demonstrated the ability of the Weak Formulation of the Conjugate Gradient FFT method to predict the EM-field of the AMC-4 waveguide array hyperthermia system, including effects due to bolus size variations. However, based on the comparison of the measured EM-field distributions and those obtained from simulations, the accuracy of the planning system is found to be insufficient for quantitative SAR dosimetry for individual patients. Qualitative SAR dosimetry can be applied in cases where the accuracy is of minor importance, e.g. for the retrospective analysis of problematic hyperthermia treatments. Prospective applications of the treatment planning system include the (qualitative) determination/simulation of a set of starting points giving a 'close to optimal' amplitude and phase setting, the prediction of possible problem areas and the analysis of the performance of new/improved hyperthermia devices.

Ultrasound power deposition model for the chest wall

An ultrasound power deposition model for the chest wall was developed based on secondary-source and plane-wave theories. The anatomic model consisted of a muscle-ribs–lung volume, accounted for wave reflection and refraction at muscle-rib and muscle-lung interfaces, and computed power deposition due to the propagation of both reflected and transmitted waves. Lung tissue was assumed to be air-equivalent. The parts of the theory and numerical program dealing with reflection were experimentally evaluated by comparing simulations with acoustic field measurements using several pertinent reflecting materials. Satisfactory agreement was found. A series of simulations were performed to study the influence of angle of incidence of the beam, frequency, and thickness of muscle tissue overlying the ribs on power deposition distributions that may be expected during superficial ultrasound (US) hyperthermia of chest wall recurrences. Both reflection at major interfaces and attenuation in bone were the determining factors affecting power deposition, the dominance of one vs. the other depending on the angle of incidence of the beam. Sufficient energy is reflected by these interfaces to suggest that improvements in thermal doses to overlying tissues are possible with adequate manipulation of the sound field (advances in ultrasonic heating devices) and prospective treatment planning.

Comprehensive Breast Centers: Priorities and Pitfalls.

Comprehensive breast centers are developed for a variety of reasons, but the major motivations are usually to reduce psychological morbidity, develop an interdisciplinary team, provide comprehensive services in a patient-focused manner, improve clinical and emotional outcomes, and develop an organized "system" of care. However, the development of "comprehensive" breast centers presents far more of a challenge than a breast-imaging center and must be undertaken with great care and commitment. If the medical staff and operational issues are not appropriately identified and addressed, the long-term success will be threatened. Each breast center is different, but some of the principal priorities and pitfalls are described. The priorities relate to breast subspecialization, access and coordination, prospective treatment planning, and comprehensive programmatic services. Among the many potential pitfalls, the focus in this article is operational and OncoPolitics.

A prospective evaluation of hepatic resection for colorectal carcinoma metastases to the liver: Follow-up report

Single institution studies of hepatic resection have implied that some subsets of patients with metastases from colon and rectum adenocarcinoma can be cured by surgery. However, it is unknown how such patients can be selected and what, in fact, the ultimate cure rate is. The objective of this multi-institutional study was to define in a prospective manner how many patients predicted to have resectable liver metastases actually could undergo curative resection and what the disease-free and overall survival were. A prospective 15-institution treatment plan included all patients who were predicted to have resectable metastases from colon and rectum cancer primaries. Results were compared among patients who underwent successful resection, patients who underwent resection with pathologically defined inadequate margins, and patients who underwent exploration but were found at surgery not to have resectable liver metastases. Fourteen institutions throughout North America and one in Milan who were members of the Gastrointestinal Tumor Study Group at the inception of this protocol in July of 1984 participated in the study. The patient population consisted of all those with metachronous or synchronous metastases from colon or rectum adenocarcinoma seen during a consecutive 3 1/2 year period with protocol registry at the time liver metastases were predicted to be isolated and resectable. Intervention consisted of the application of standard preoperative screening tests, abdominal exploration, and resection of all patients who had liver-only surgically resectable disease. The main outcome measures were: Accuracy of preoperative staging, acute and chronic operative morbidity, and disease-free, as well as overall, survival among the three treatment groups. The minimum follow up on all surviving patiens after curative resection was 2.2 years, with a median follow up of 3.2 years. Median survival times for patients receiving curative and noncurative resections and for those receiving no resection were estimated to be 35.7, 21.2, and 16.5 months, respectively. No statistically significant difference in the survival distribution of the noncuratively resected or the non-resected patients was observed. The survival distribution of curatively resected patients remains statistically superior to the distribution of noncuratively resected patients and those receiving no resection (P=0.01). These results confirmed that, although liver resection for hepatic metastases from colorectal car cinoma is safe to do and presently constitutes the only standard curative treatment for potentially resectable disease, it ultimately cures few patients.

Fast and efficient computer modeling of ferromagnetic seed arrays of arbitrary orientation for hyperthermia treatment planning

Purpose : Effective hyperthermia treatment planning requires an ability to predict temperatures quickly and accurately from an arbitrary distribution of power. Our purpose was to design such a fast executing computer code, MGARRAY, to compute steady-state temperatures from ferromagnetic seed heating, allowing seeds to have arbitrary orientations and to be curved to permit more realistic modeling of clinical situations. We further required flexibility for the tissue domain, allowing inhomogeneity with respect to thermal conductivity and blood perfusion, as well as an arbitrary shaped boundary. Methods and Materials : MGARRAY uses multigrid methods and a finite volume discretization to solve the Pennes bioheat transfer equation in three dimensions. We used MGARRAY to compare temperature distributions that result from an array of straight, parallel seeds and from an array of seeds that were curved and tilted randomly by 13°. Results : On a personal workstation the Central Processing Unit (CPU) time of MGARRAY was under 4 min. We found that the median temperature in a predetermined target volume was ∼0.8°C higher in the straight array than in the curved array. At specific locations within the target volume temperature differed by ∼0.5−0.9°C, but could differ by up to several degrees, depending on proximity to a seed and the level of blood perfusion. Conclusion : These differences can impact on retrospective analyses whereby temperatures at a few locations are used to infer the overall temperature field and blood perfusion levels. The flexibility and computational speed of MGARRAY could potentially lead to a substantial improvement in both retrospective and prospective hyperthermia treatment planning.

Nonoperative management of blunt abdominal trauma: The role of sequential diagnostic peritoneal lavage, computed tomography, and angiography

To determine the usefulness of sequential nonoperative diagnostic studies in the evaluation and treatment of stable patients after blunt abdominal trauma. Retrospective review of a prospective treatment plan in a large urban Level I trauma center. Fifty-two patients deemed stable after initial evaluation following blunt abdominal trauma. Patients with a positive diagnostic peritoneal lavage for red blood cells underwent abdominal computed tomography (CT) scanning. If CT demonstrated a visceral injury, it was followed by diagnostic angiography. Attempts were made to treat on-going bleeding by transcatheter embolization. Fifteen patients had negative CT scans and were successfully observed. In the other 37 patients, CT identified 17 liver, 16 splenic, and eight kidney injuries; eight extra-peritoneal bleeds; and one mesenteric hematoma. Six of these patients were observed. Thirty underwent diagnostic angiograms. Twelve had no active bleeding, and all were observed successfully. Seventeen underwent successful embolization of the bleeding site(s). One had injuries not controllable by embolization and required exploration. Six patients required laparotomy later in their course, but none had intra-abdominal bleeding or a missed intestinal injury. Despite being performed after diagnostic peritoneal lavage, CT missed only two injuries. There was one main complication, delayed recognition of a diaphragmatic injury. Three patients died, two from multiple organ failure and one from a pulmonary embolus; none was believed to be related to this technique. With our algorithm, 45 patients (86%) were spared laparotomy. Diagnostic peritoneal lavage and CT are complementary when evaluating blunt abdominal trauma. Diagnostic peritoneal lavage is an effective screening tool. CT may be reserved for stable patients with a positive diagnostic peritoneal lavage to specify the organs injured. Bleeding often may be treated by embolization, limiting the rate of surgery.

MABDOS: a generalized program for internal radionuclide dosimetry

Dosimetry calculations of monoclonal antibodies (MABs) are made difficult because the focus of radioactivity is targeted for a nonstandard volume in a nonstandard geometry, precluding straightforward application of the MIRD formalism. MABDOS, a program for performing internal radionuclide dosimetry, addresses this shortcoming. It accounts for the perturbations introduced by the inclusion of tumor(s) as additional source/target of radiation. Biodistribution data are conformed to a compartmental model, allowing the forward simulation of compartmental activity. Integration of the resultant time-activity curves yields cumulative activities for each compartment. Allowing compartments to represent physical organ spaces, cumulative activities are loaded into a column vector representing radionuclide source organs. A matrix multiplication between column vector and the appropriate S table is carried out. S factors for tumors as source and target organ are calculated by treating the tumor as a spherical perturbation to Standard Man geometry, and carrying out a Monte Carlo simulation on-the-fly. The software presents an integrated modeling/dosimetry environment and offers a viable methodology for performing prospective treatment planning.

Controversies and hazards in the treatment of pit viper bites.

This paper discusses the pathology produced by pit viper venom and the pharmacologically active substances released by the action of venom on human tissue. The risks of many of the popular methods of treatment such as tourniquets, cryotherapy, incisions, excisions, and cortisone are also discussed. A prospective treatment plan was devised which was limited to measures of proven benefit, and 28 patients were treated with no mortality or tissue necrosis.