A radiolucent bite-block apparatus.

A bite-block, patient immobilization apparatus has been constructed using all plastic parts. The apparatus may be used in C-T scanning without detriment to the images produced. The construction details are given and the procedure used to produce a bite block is described. A method to reduce electron backscattering onto the buccal mucosa from metal fillings is given.

A basis for blocking the spinal cord in opposed field irradiation.

The concept of partial tolerance is applied to the equivalent dose formula for spinal cord tolerance to allow for the change in dose when open and blocked fields are used in a course of radiotherapy. The field arrangement considered is parallel opposed irradiation. Certain assumptions are made regarding the contribution of dose to the spinal cord from open and blocked fields, which allows for the development of an equation to calculate the number of fractions that require spinal cord shielding in the posterior field. The use of a form to facilitate these calculations is described.

A port film marker.

A device is described consisting of brass strips embedded in a plastic plate. When inserted in a radiation beam, it produces an image of a cross centered in the field. Cuts in the brass at defined intervals project a scale on the film used to determine a magnification factor. A marker in the lower right-hand quadrant provides rapid, unequivocal orientation of the film. This capability of orientation to a beam's-eye-view makes anatomical markers redundant.

Radiotherapy treatment planning using lymphoscintigraphy.

A method for the three dimensional location of lymph nodes with respect to the skin surface is described. The technique is based on the reconstruction of surface shape using isocentric radiographs taken with metal chains draped on the patient. Registration of the radiographic study to the lymphoscintigraphic study is accomplished automatically by matching the location of four radiopaque and radioisotope markers. This method allows nodes to be located in a beam's eye view with any set up of an isocentric radiotherapy machine. An accurate determination of the depth of lymph nodes is obtained, which is of value in electron beam therapy.

Oral pilocarpine for radiation-induced xerostomia: integrated efficacy and safety results from two prospective randomized clinical trials.

PURPOSE: Pilocarpine hydrochloride administered in either a fixed-dose or in a dose-titration protocol three times a day for 12 weeks was evaluated for its ability to relieve symptoms of postradiation xerostomia and to improve saliva production. The studies were randomized, double-blind, placebo-controlled, multicenter clinical trials. A total of 369 patients who had received at least 40 Gy of radiation to the head and neck with clinically significant xerostomia were enrolled in the two studies. In the dose-titration study, 162 patients were enrolled and they received a thrice daily regimen of 2.5 mg tablets for first 4 weeks, 5.0 mg tablets for the second 4 weeks, and 10.0 mg tablets for last 4 weeks of a 12-week study. Patients in the titration study were allowed to down titrate following at least one dose escalation to alleviate bothersome side effects, if any. In the fixed dose study, 207 patients received either placebo, 5.0 mg, or 10.0 mg tablets t.i.d. for 12 weeks. METHODS AND MATERIALS: Patients were evaluated for symptomatic relief by responding to questionnaires using visual analog scales and categorical questions; and, for saliva production by sialometry. Questionnaires measured relief of intraoral dryness, improvement in overall condition (global response), oral discomfort, difficulty in speaking, chewing and swallowing, denture wearing, and usage of artificial saliva. Evaluations were conducted at baseline, and weeks 4, 8, and 12. RESULTS: There were statistically significant improvements in salivary flow in pilocarpine treatment groups vs. placebo. There was a significant improvement in the overall "global" condition of xerostomia associated with the use of pilocarpine in both studies. In the fixed-dose study, there were significant improvements in oral dryness, mouth comfort, ability to speak, and reduction in the use of oral comfort agents. The dose-titration study showed improvements in dryness that approached significance (p = 0.057) and a decreased use of oral comfort agents (p = 0.045). All pilocarpine dosages (2.5, 5.0, and 10.0 mg three times a day) were judged to be safe. Adverse experiences were those expected for a cholinergic agonist, with the most common being mild to moderate sweating. The incidence of these events increased by dose. CONCLUSION: It is concluded that in these studies pilocarpine produced clinically significant benefits with acceptable side effects and risks for the treatment of symptomatic postradiation xerostomia. The incidence of most adverse events increased with dose. Best results may require continuous treatment for more than 8 weeks with doses greater than 2.5 mg three times a day. A 5.0 mg thrice daily regimen produced the best clinical results when both efficacy and side effects were taken into consideration. There may be some patients who would experience some additional benefit by increasing the dose to 10 mg thrice daily.

Coronary artery disease following mediastinal radiation therapy.

Coronary artery disease occurred in four young men (mean age 41 years) who had received curative irradiation therapy for mediastinal malignancies 12 to 18 (mean 15) years previously. None was at high risk for developing coronary artery disease by Framingham criteria. Angiography demonstrated proximal coronary artery disease with normal distal vessels. Distribution of the lesions correlated with radiation dosimetry in that vessels exposed to higher radiation intensity were more frequently diseased. Three patients had coronary bypass grafting for intractable angina and are asymptomatic at 10 to 43 months. A total of 163 patients underwent mediastinal irradiation for lymphoma or thymoma between 1959 and 1980. Among the 29 who survived 10 or more years, five (18%) developed severe coronary artery disease, implicating thoracic radiotherapy as an important risk factor. Because of the importance of mantle irradiation in the treatment of lymphomas, the prevalence of these neoplasms, and the survival patterns following treatment, many long-term survivors may be at increased risk for the development of coronary artery disease. Recognition of the relationship between radiotherapy and coronary artery disease may lead to earlier diagnosis and more timely intervention. Standard surgical treatment may be particularly beneficial because of the relative youth of most of these patients and because the proximal distribution of typical lesions increases the likelihood of complete revascularization.

Quality control of radiation therapy in multi-institutional randomized clinical trial for localized prostate cancer.

The National Prostatic Cancer Project (NPCP) from 1978 through 1985 compared definitive radiation therapy for Stages B2, C, D1 lesions in those who received only radiation treatment to those who received two years of additional cyclophosphamide (Cytoxan) or estramustine phosphate (Emcyt) chemotherapy. Two hundred fifty-four patients were entered and 229 evaluated for compliance of the spatial localization of the prostate through review of the simulation and port films. In 78 per cent this was satisfactory, whereas in 12 per cent it was unsatisfactory, and another 10 per cent were not evaluable. The principle cause of an unsatisfactory rating was failure to adequately cover the prostatic target volume, especially the apex which was found to be variable in location. Routine use of retrograde urethrocystography is urged as part of the localization method in patients to receive definitive external beam radiation therapy for prostate cancer. The role and impact of quality assurance programs for radiotherapy in cooperative clinical study groups is reviewed and discussed.

Combination transurethral resection, systemic chemotherapy, and pelvic radiotherapy for invasive (T2-T4) bladder cancer unsuitable for cystectomy: a phase I/II Southwestern Oncology Group study.

OBJECTIVES: Primarily to evaluate the toxicity and, secondarily, the tumor response and patient survival associated with a three-phase combined modality treatment plan for patients with invasive transitional cell carcinoma (TCC) of the bladder (T2-T4,NX-N2, MO) who are medically unsuitable for or who refuse cystectomy. METHODS: Eligible patients initially underwent extensive transurethral resection (TUR) of the primary tumor with the attempt to resect disease totally. Subsequently, they received systemic combination chemotherapy consisting of two cycles of methotrexate, cisplatin, and vinblastine (MCV), followed by cystoscopic re-evaluation of the bladder tumor. Patients then received 6480 cGy radiotherapy to the bladder with concurrent systemic cisplatin. Toxicity, primary tumor response, and overall survival were evaluated. RESULTS: Of 34 eligible patients, 27 patients completed the treatment series. Twenty-two received 80% to 100% of the prescribed doses of MCV and only 2 patients experienced grade 4 hematologic toxicities. The most common toxicities were gastrointestinal (23), hematologic (21), and renal (8). The complete response (CR) rate after all treatment phases was 56% (19 of 34), 10 patients achieving a complete tumor resection of visible tumor at the initial TUR of the bladder (TURB); 3, a CR after MCV; and 6, after radiotherapy and concomitant cisplatin. The median overall survival was 21 months with 6 of 34 (18%) alive at 57 months (range, 36 to 75). Complete resection of tumor by TURB was associated with prolonged overall survival. The bladder was the initial site of recurrence in 85% of patients who had achieved a CR status. CONCLUSIONS: This older age patient group tolerated this combined modality therapy with acceptable toxicities, but the overall survival rate was not improved compared with those reported with radiotherapy alone.

Extramedullary facial plasmacytomas with anaplastic features: a diagnostic dilemma with implications for treatment.

Extramedullary plasmacytomas (EMPs) are rare plasma-cell tumors of the soft tissue that occur predominantly in the nasal sinuses and oropharynx. Subcutaneous and cutaneous plasmacytomas of the face are distinctly unusual. The authors report a case of rapidly expanding EMP involving the lip and contralateral nasolabial fold of a native Alaskan man with a 25-year history of recurring solitary bone plasmacytomas (SBP). An incisional biopsy revealed sheets of monotypic plasmablasts with anaplastic features. The pathologic and clinical findings were most consistent with a Richter transformation from a low-grade to a high-grade malignancy, or anaplastic myeloma (AM). With combined chemotherapy and radiation therapy, he achieved a complete response. The clinical and laboratory features of this most unusual plasma-cell dyscrasia are reviewed with an emphasis placed on diagnosis and treatment.

A method for the assessment of the output of irregularly shaped electron fields.

A simple approach to the calculation of dose in cone-collimated electron fields is presented. The method accounts for variations in lateral scatter with field size using a Clarkson Integration. The reduction in output by an irregularly shaped aperture is evaluated based on measurements of the output at various distances from the aperture in a field 2.5 cm in diameter. The first 14 months of clinical use were analysed and it is shown that in 42 out of 600 calculations, the cutout factor was less than 0.95 and that in 77% of these, the calculation method was accurate to +/- 3%.

An isocentrically mounted stand for total body irradiation.

The purpose of this study was to construct a stand to support a patient for total body photon irradiation and to expedite the set-up and treatment by rotating the stand. As in other isocentric treatments, the midline dose is impacted less by source-to-skin distance variations. The method of immobilizing the patient is described. A 10 mm lucite plate is supported in front of the patient to increase skin dose. A matrix of holes in this plate serves to index the location of blocks used to shield the lungs. The dosimetry of the set-up is described, as is the production of tissue deficit compensators. The results of phantom studies and in vivo thermoluminescent dosimetry measurements are presented.

An estimate of the margin required when defining blocks around the prostate.

The portal films of 54 consecutive patients treated for primary prostate cancer have been compared to the simulation films. The systematic and random uncertainty in the set-up, defined by the couch movement required to move the patient to the simulated position, was determined to be 1.6 mm UP (SD 3.3 mm), 0.3 mm RT (SD 2.6 mm) and 1.3 mm IN (SD 2.4 mm). The area of fields defined on simulation films was compared with that on portal films to determine the error in block production which was -0.7 mm (SD = 0.9 mm). Five sources of uncertainty in the radiotherapy have been identified, three occur before and two during the course of treatment. A method for combining these uncertainties is proposed and used on the data obtained in this study. This provides estimates of the margin required when drawing blocks so that the minimum dose to the target is 95% of the prescription in 95% of treatments. The block margins are not uniform and range from 21 mm, when drawing the block outline to the posterior on a lateral film, to 13 m when drawing laterally on an anterior film.

A frameless method for stereotactic radiotherapy.

A frameless method for stereotactic multiple arc radiotherapy (SMART) is described. Three short gold wires are implanted in the scalp approximately 100 mm apart. These are localized in a computed tomographic or angiographic study along with the target. Subsequently the gold markers are localized on beam films and the target position calculated using a computer program ISOLOC. This program provides the couch movements required to move the target to the isocentre and a micropositioner attached to the couch is used to make the adjustment. Beam films are repeated until the movements required are less than 1 mm in any direction. It is shown that the simple procedures of implanting the markers subcutaneously do not provide a stable reference system in about 25% of patients and the markers are now screwed into the cranium. The precision of the method is evaluated by phantom studies and measurements taken during several hundred treatments.

The incorporation of partial shielding of the spinal cord in a tissue deficit compensator in radiotherapy of the thorax.

A method to determine the shape of a patient by placing radiopaque wires and chains on the skin and taking two isocentric X-ray films is described. The wire locations are reconstructed by X-ray stereo photogrammetry, and a beam's eye view of the wire frame structure can be obtained with reference to the original setup of the "stereo-pair" films. An algorithm for paving between the wires with triangular plates is described which allows the calculation of the tissue deficit distance and compensator thickness. The depth and distance to points on the spinal cord are calculated, and the dose rate is calculated using a standard irregular field computation program. The limit for spinal cord tolerance is specified in terms of the maximum daily dose based on an equivalent dose formula. The additional thickness of compensator, required for the posterior field compensator to satisfy the tolerance limit, is calculated. The technique readily accommodates the kyphotic and scoliotic spine and has been in routine clinical use for seven years.

Practical 3-D radiotherapy planning of brain tumors.

In postoperative radiotherapy of brain tumors it is usually the case that preoperative imaging studies, either CT or MRI, were performed outside of the purview of the radiation therapy department. Thus the target volume is defined in an imaging study that does not lend itself readily for entry to a 3-D treatment planning system. A method is described that adjusts the patient structure defined by scan data to an appropriate position for radiotherapy. Software tools that are simple to use have been incorporated in a 3-D treatment planning program that allows oblique treatment planes to be defined. The program provides beam's-eye-view plots of the fields that are used to overlay simulation films and will automatically describe a field blocking outline that provides a prescribed margin on the target volume or other structures that have been defined. Finally, dose calculations in arbitrary planes through the head are made and isodose plots produced.

Radiation therapy for localized prostate cancer.

Since 1965, 401 patients with prostate cancer have received intensive local pelvic radiation therapy at the Virginia Mason Medical Center. Two hundred seventy-seven of these patients were treated from 1965 through 1975, comprising the study group. Two hundred twenty-one of this series were in the Stage C category. The 36 Stage B cancers were either medically nonoperable, or advanced extent, or had high-grade histopathology. Ten patients each were in diffuse Stage A or Stage D groups, the latter receiving local palliative intensive treatment to the prostate area. The mean age of the patients was 67.6 years. The five year survival of the Stage C group was 57.7%. There was no apparent influence on the survival of irradiated Stage C patients who received estrogen therapy. Current treatment techniques employ 10 megavolt photon beam with whole pelvic nodal fields and bilateral arc rotational boost fields. The incidence of reactions and complications is presented.

Are pelvic irradiation and routine staging laparotomy necessary in clinically staged IA and IIA Hodgkin's disease?

Thirty-nine patients with clinically staged IA and IIA Hodgkin's disease were treated with mantle plus paraaortic/splenic irradiation between 1968 and 1975. All patients had supradiaphragmatic presentations, and none had staging laparotomies. With a follow-up time of 1 to 9 years, mean 4.3 years, the overall relapse-free survival is 92% (100% for stage IA and 89% for stage IIA). The absolute relapse-free 5-year survival is 91% There were no pelvic recurrences. These data show that routine staging laparotomy and pelvic irradiation are not indicated for clinically staged IA and IIA Hodgkin's disease with supradiaphragmatic presentation. The criteria for staging laparotomy in early-stage Hodgkin's disease are discussed.