An articulating retractor holder to facilitate laparoscopic adrenalectomy and nephrectomy.

PURPOSE: Minimally invasive surgical approaches to renal and adrenal tumors have gained increasing use. The addition of robotic assistance and mechanical devices has decreased the number of assistants required for these often long cases. We describe an articulating arm retractor holder to aid in liver and spleen retraction during laparoscopic surgery. MATERIALS AND METHODS: The articulating retractor holder consists of 4 components, including a base rod, flexible extension arm, stainless steel precision clamp and table attachment. During laparoscopy the abdomen is visualized using standard approaches. The articulating retractor holder is clamped to the table via the base rod and brought into the surgical field using sterile technique. A retractor is placed intracorporeally to elevate the liver or spleen and the handle is secured in place using the precision clamp. RESULTS: The articulating retractor holder was used in all right and approximately 50% of left laparoscopic cases. Adequate visualization was obtained in all patients. There were no device failures or retractor related complications. CONCLUSIONS: The articulating retractor holder is a useful tool to aid in laparoscopic retraction that should be added to the urologist armamentarium.

Head and neck compensation for total body irradiation using opposed laterals.

Using shaped brass compensators that follow the coronal profile of a patient's head and neck, we confirm that adequate compensation can be made to prevent overdosing in these regions when delivering total body irradiation using opposed lateral fields. Initially, these compensators were custom made for each patient, but we have shown that the variation from patient to patient is sufficiently small that individual compensators can be used for a number of different patients without compromising the dose distribution. In a subgroup of 35 patients on whom diode measurements were made, 20 used compensators from the library of approximately 40 compensators made for previous patients and 15 required new compensators to be fabricated. No significant difference (3.4% on average) was observed in the dose distribution. By examining the profiles accumulated from 81 patients, we have shown that the primary difference between patients is not in the shape of the head and neck, but in the distance from the top of the head to the suprasternal notch and in the slope of the shoulders; thus, shaped compensators are not necessary and the same quality of dose homogeneity can be achieved using simple flat brass plates. Further, if the arms are supported so that the slope of the shoulders is constant, a relatively small number (15) of square-ended plates of thickness ranging from 4.0 to 11.0 mm would be sufficient to treat all 81 patients in our sample.

A simple CT aperture emulator for use with a radiotherapy simulator.

Tumor localization in radiation treatment planning often involves the generation of quantitative anatomical data from multiple imaging modalities. It is desirable to take all of the images in the selected treatment position, which is usually decided upon during the initial simulator session. The different scanning modalities are often operated by different staff, at different times and in different locations; thus, it is difficult to ensure consistency in the position of the patient's body, and its documentation, at various times and places. Also, devices such as CT and MR scanners frequently pose restrictions due to their limited apertures. Failure to consider the physical limitations of such scanning equipment at the time of simulation or localization may result in placing the patient in a treatment position which will not fit through the aperture of the CT (or MRI) scanner, or which will result in a clinically important portion of the anatomy being "cut off" in the resulting scans. This can lead to re-simulation of the patient or result in a lack of accurate coordination of simulator and CT scan data. To minimize problems such as these, we have developed a CT Aperture Emulator which can be used at the time of the initial simulation. This is a lightweight "halo" easily attached to the simulator, which mimics the size and shape of the CT aperture. It permits reproducible adjustment of the patient's position, while allowing technologists and physicians to set up the patient with respect to potential CT constraints, in particular with regard to the use of immobilization and support devices. The emulator device also facilitates reproducing a patient's treatment position on the CT scanner. The concept has been found to have additional clinical uses and can be extended to a variety of imaging equipment.

A light-diffusing device for intraoperative photodynamic therapy in the peritoneal or pleural cavity.

Light delivery to anatomic areas involved by tumor is critical for effective photodynamic therapy. The authors provide a detailed overview of a light-diffusing device which they have used for intraoperative illumination of the peritoneal and pleural cavities in patients with tumors involving the surfaces of these cavities. Their device represents an inexpensive modification of widely available endotracheal tubes. It has been used to deliver intraoperative photodynamic therapy in over 50 patients without episodes of device failure. When combined with a lipid-based, light-diffusing medium and on-line power/energy density monitoring, it allows homogeneous illumination of these complex surfaces.

An isocentric chair for the simulation and treatment of radiation therapy patients.

There are a variety of clinical situations in which patients undergoing radiation therapy can benefit from being treated in an upright position. The authors describe a new design for a treatment chair to assist in accomplishing this task. The present chair differs from previous designs in that it can be used with existing radiotherapy simulators as well as treatment units and that it permits isocentric setup and treatment of tumors either at the nominal source-to-axis distance (SAD) of a machine or at extended distance. This design permits treatment of mediastinal tumors as well as those of the head and neck using a variety of field arrangements including AP-PA, opposed laterals, and multiple obliques. The seat is designed on the "tool platform" principle. A wide variety of devices can be attached onto it to ensure accurate and reproducible, yet comfortable, patient positioning.

A flexible cystoscope holder/surgical retractor that really works.

Stabilization of equipment during endoscopic procedures frequently presents a problem. Most attempts to anchor a cystoscope have been cumbersome or have afforded transient stability. We describe an easily adjustable, flexible cystoscope holder that may be attached readily and locked in place after positioning. The unique open-sided clamp allows for a firm but delicate grasp of fiberoptic instruments. In addition to this function the flexible cystoscope holder may be adapted easily to become a surgical retractor. Our experience with this instrument has led to greater versatility during endoscopic and open procedures.

125I interstitial brachytherapy for primary malignant brain tumors: technical aspects of treatment planning and implantation methods.

Use of interstitial radiation holds promise in the treatment of primary malignant brain tumors, but optimal technical factors have yet to be determined. We have developed a method of precise CT directed stereotactic placement of radioactive sources in a predetermined target volume. We use low activity (1-2 millicurie/speed) sources of 125I loaded in silastic catheters, which are positioned in a parallel array in the target. Positioning of such multiple sources toward the periphery of the volume enhances achievable dose homogeneity. Seeds of various activities can be differentially loaded into each catheter and the catheters can be positioned at various radii from the central target so that the treated volume corresponds to the identified (often irregular) target volume. Although the implant is designed to be permanent, the sources can be removed easily in a second procedure.

Intraoperative radiation therapy at the National Cancer Institute: technical innovations and dosimetry.

The technical complexity of intraoperative radiotherapy (IORT) requires modification of the standard physical and dosimetric methods used in external electron beam therapy. At the National Cancer Institute, a number of technical innovations have been integrated into ongoing clinical studies of IORT. These include: (1) an electron beam applicator system that is significantly different from other IORT systems and includes customized "squircle" applicators; (2) peripheral dose shields; (3) a modified surgical table replacing the standard radiation treatment couch; and (4) routine use of multiple IORT fields that necessitates field matching. The IORT applicator system and related devices and techniques are dosimetrically characterized in detail both for use in the IORT program and in order to illustrate many useful facets of electron dosimetry.

Treatment of murine intraperitoneal ovarian ascitic tumor with hematoporphyrin derivative and laser light.

An ascitic murine tumor, ovarian embryonal carcinoma, was used as a model of human ovarian carcinoma restricted to the peritoneum. The tumor was treated with a combination of hematoporphyrin derivative (HPD) and i.p. 514-nm laser light. Mice were given injections of 2 X 10(5) tumor cells, and by 9 days, there were 2 to 4 g of ascitic tumor/mouse. On Day 9, mice (68) were treated as follows: (12) no treatment; (12) only HPD (50 mg/kg i.p.); (12) laser only (9.6 J for 16 min); and (32) HPD (50 mg/kg i.p.) and 2 h later, laser treatment. On Day 15, a second treatment with HPD and laser was given to 15 mice. All mice not receiving HPD-laser treatment died between Days 20 and 23. The response rate as determined by decrease in weight and abdominal size for HPD-laser-treated mice was 90%, but the response was short, and all but one animal died by Day 34. However, 6 of 15 of the twice-treated group are alive at 90 days and considered cured. Photoradiotherapy with HPD for i.p. ascitic tumors appears to have promise as a treatment modality.

Peripheral dose to the testes: the design and clinical use of a practical and effective gonadal shield.

A simple and practical gonadal shield has been developed for use near megavoltage radiation fields. The lead shield encloses only the testes, allowing its use with nearly any radiation field that does not include the testes. The dose to the testes with and without the shield has been measured extensively both in phantoms and on patients. The gonadal shield allows a 3 to 10-fold reduction in dose to the testes depending primarily on the distance from the field edge to the gonads. When the shield is used, the gonadal dose is always less than 1% of the patient's prescription dose. Based on our patient studies of testicular injury following conventionally-fractionated irradiation, a dose of less than 50 cGy (1% of a typical 5000 cGy treatment regimen) should preserve normal testicular function.

A simple system for manual image reconstruction from pairs of X ray films.

A simple mechanical back-projection system for X ray films is described which is easy to construct and implement. It enables mechanical simulation of the X ray geometry used when taking pairs of isocentric radiographs for reconstruction purposes. Such pairs may be conventional "AP and Lateral" sets but often it is preferable to take them in oblique directions on the order of 90 degrees apart. The device and the reconstruction method have proved to be very useful in determining target volumes for radiation treatment planning, especially if surgical clips and/or distinct anatomical structures are present. As an instructional tool it has advantages over an also locally developed computer-assisted method of reconstruction. The present system has proved to be highly useful especially in delineating the target volume for treatment planning of soft tissue sarcomas of the extremities and peripheral parts of the body, where detailed and accurate tailoring of shielding blocks is often of vital importance.

Simplified bite-block immobilization of the head.

The use of bite blocks to immobilize a patient's head for therapeutic radiology usually involves the mechanical positioning of a rod protruding from the block. This position must be recorded at simulation time and preset for each treatment session. The authors describe a device which simply requires the vertical positioning of an auxiliary bar which, in turn, is attached vertically to the primary rod at simulation time.

Television system for verification and documentation of treatment fields during intraoperative radiation therapy.

Intraoperative radiation therapy (IORT) involves direct treatment of tumors or tumor beds with large single doses of radiation. The verification of the area to be treated before irradiation and the documentation of the treated area are critical for IORT, just as for other types of radiation therapy. A television system which allows the target area to be directly imaged immediately before irradiation has been developed. Verification and documentation of treatment fields has made the IORT television system indispensable.