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Biomedical subjects

M Wollin

Publications and source records attributed to M Wollin.

At least 19 recordsLinked to original sources
PubMed1992

Iodine125 interstitial brachytherapy in the treatment of carcinoma of the lung.

In a prospective study, 14 patients with primary non-oat cell lung carcinoma were treated with intraoperative Iodine125 (I125) implantation of the lung tumor via lateral thoracotomy or median sternotomy. Staging mediastinal node dissection was performed in each case. Patients were selected when wedge or segmental resections were not technically feasible, such that lobectomy or completion pneumonectomy would have been required or pulmonary function studies were poor. Doses ranged from 8,000 cGy at the periphery to 20,000 cGy at the center. With a minimum 12 month follow-up, mean and median survivals were 16.7 and 15.1 months, respectively. Local control was achieved in 10 of 14 patients (71%) with all local failures occurring in pathologic stage III patients. When separated according to tumor size, local control was obtained in six of seven tumors of less than 3 cm and four of five tumors of 3-5 cm. Both cases with masses greater than 5 cm failed locally. There was one operative mortality and two postoperative complications. All other patients were discharged within one week of surgery. There was no radiation pneumonitis. I125 lung brachytherapy is an excellent alternative treatment for T1 and T2 tumors when medical conditions preclude curative resection.

Aged↗
PubMed1991

Predicting normal tissue injury in radiation therapy.

We tested three radiobiologic models, the nominal standard dose (NSD), the biologic index of reaction (BIR), and the linear quadratic (LQ) models to determine which best predicts normal tissue injury in radiation therapy. Clinical data for radiation myelopathy, rib fracture and pericardial effusion were used for all three models to predict injury. We assumed that on the average injuries occurred at higher equivalent doses of radiation than were received by patients who were not injured. We used a t-test to determine whether there were in fact significant differences in the mean values of the equivalent doses among the injured and non-injured. The means were calculated for the four sets of injury by the three models. For the LQ model it was necessary to choose a value for the parameter alpha/beta; the results were not sensitive to the choice over the range of 1/2 to 12 Gy. None of these models showed a significant difference between injured and non-injured patients for all four sets of data. The BIR model showed significant differences in three sets, the LQ model was significant in two and marginally significant in one set, and the NSD was significant in two sets. This analysis illustrates therefore, that the linear quadratic model can be adopted for analysis of clinical data with results that are no worse and possibly better than the NSD model.

Humans↗
PubMed1990

The CT scanner as a therapy machine.

Many tumors in the brain and in other tissues can be delineated precisely in images obtained with a CT scanner. After the scan is obtained the patient is taken to another room for radiation therapy and is positioned in the beam with the aid of external markers, simulators or stereotactic devices. This procedure is time consuming and subject to error when precise localization of the beam is desired. The CT scanner itself, with the addition of a collimator, is capable of delivering radiation therapy with great precision without the need for external markers. The patient can be scanned and treated on the same table, the isocenter of the beam can be placed precisely in the center of the lesion, the beam can be restricted to just those planes in which the lesion appears several arcs can be obtained by simply tilting the gantry, and the position of the patient in the beam can be monitored continuously during therapy. We describe here the properties of the CTX, the CT scanner modified for therapy.

Animals↗
PubMed1990

Optimization of arc angles in rotational therapy.

Data is presented that will aid in optimizing the arc angles used for rotational therapy for a 6 Mv x-ray beam. Computer calculations of isodose distributions were carried out and the Ap and Lateral dimensions of the 95 and 100% isodose line were tabularized as a function of the field width (6-14 cm), distance between isocenter and patient midline (0-3 cm), and bilateral 120 or 100 degrees arc angle. The 300 degrees rotation cases we studied were generally found to be inferior to 120 degrees or 100 degrees bilateral arc rotations. 120 degrees arcs are best when the target center is within 2 cm of the patient's Ap center. As that separation increases, the bilateral arc angle should be decreased or wedges should be rotated through 300 degrees to avoid maximum doses greater than 105%. The data tables can be used as a starting point for computer calculations to select the field width and the arc angle for a particular target location and size. Of note is the degree to which the dimensions of the 100% isodose line decreases for small field widths and large isocenter to patient midline distances.

Humans↗
PubMed1990

Buried penis. A novel approach.

Buried penis is a congenital abnormality in which the phallus is concealed within the subcutaneous tissue. The corporal bodies and glans have developed normally. A deficiency of penile shaft skin in association with abnormal mobility of the skin gives rise to the phenotypic appearance. The skin defect may be related to an abnormal attachment of dartos muscle during embryogenesis. Correction of this condition requires separation of these abnormal muscular attachments and provision of skin coverage of the penile shaft. It is imperative not to circumcise the patient as this will worsen the skin deficiency. We describe a novel technique for correcting buried penis performed on 12 patients at the Great Ormond Street Hospital for Sick Children. A satisfactory cosmetic result was obtained in all patients.

Humans↗
PubMed1989

Treatment selection for base of tongue carcinoma.

Sixty-two previously untreated patients with squamous cell carcinoma of the base of tongue were retrospectively analyzed. The American Joint Committee on Cancer (AJCC) Stage distribution was I-3, II-7, III-24, and IV-28. The choice of treatment was nonrandomized. The local control was 10/18 with high-dose preoperative radiation, 17/30 with external beam radiation only, and 4/14 with external beam plus interstitial implantation. The median survival for the three treatment regimens were 63, 51, and 13 months, respectively. Preoperative radiation is suggested for tumors with inferior (laryngeal) spread or those with extensive superior extension (to tonsillar fossa and beyond). For centrally placed lesions in the base of the tongue (with or without lateral hypopharyngeal wall spread), radiation alone is recommended. An interstitial implantation should be restricted to lesions equal to or less than 4 x 3 x 2.5 cm3. Since this insertion is technically more demanding than for tumors of the mobile tongue, they should be performed by the more experienced brachytherapist.

Brachytherapy↗
PubMed1989

Priorities in urinary diversion following pyeloplasty.

Debate continues regarding optimal drainage following pyeloplasty. We reviewed the method of drainage in 100 consecutive dismembered pyeloplasties performed from 1983 to 1987. Of the children 20 per cent underwent pyeloplasty with placement of a nephrostomy tube and transanastomotic stent (group 1), while 80 per cent underwent pyeloplasty performed in a nonintubated fashion (group 2). A urethral bladder catheter was used in 20 per cent of the patients in group 1 and in 90 per cent in group 2. While the over-all complication rates and long-term results were similar for both groups, the nature of complications for each group differed. The intubated group had a 10.5 per cent incidence of urinary tract infection, while the nonintubated group demonstrated an 8.6 per cent incidence of postoperative anastomotic leakage. A nephrostomy tube and stent appear to be unnecessary in the routine pyeloplasty and may prolong hospitalization. Selective use of upper tract drainage may help to decrease the incidence of postoperative leakage in specific cases.

Child↗
PubMed1989

Prognostic factors for recurrence and cosmesis in 393 patients after radiation therapy for early mammary carcinoma.

Between 1978 and 1985, 393 of 2,765 (14%) patients with operable cancer of the breast (clinical stage T0-3N0-2M0) were irradiated after excisional biopsy and staging axillary dissection. Of 77 patients with microscopic axillary metastases, 68 received systemic adjuvant therapy. Treatment failed locally in 26 cases, and there were seven patients with distant metastasis. The three major factors for increased local treatment failure were (a) age below 40 years (P = .003), (b) negative estrogen receptor assay result (P = .03), and (c) failure to deliver a radiation boost dose when tumor was present at the margin of the specimen (P = .002). The size of the tumor, the nodal status, the progesterone receptor assay result, and the presence of ductal carcinoma in situ mixed with infiltrating carcinoma did not show a significant influence on local recurrence. In 274 of 393 (70%) patients, cosmesis was evaluated. The four major factors affecting cosmesis favorably were (a) utilization of a wedge (P less than .0001); (b) treatment of two fields a day (P less than .0001); (c) failure to use a separate treatment port to the regional lymph nodes, so as to avoid field junctions (P = .0003); and (d) small size of specimen (less than 50 cm2) (P = .0171). A second or third cancer was found in 39 of the 393 (10%) patients; contralateral breast cancer was the most common form (n = 23), followed by genitourinary cancer (n = 5). The most frequent complication was arm edema (6%).

Adult↗
PubMed1979

Interface radiation dosimetry in mandibular reconstruction.

When a beam of radiation crosses the interface between two substances, secondary electrons are generated. This results in enhancement of the absorbed dose of radiation roughly proportional to the difference in atomic numbers. Interfaces are created in reconstruction of the mandible with implantable trays containing hematopoietic bone marrow and cancellous bone chips. Radiation was measured in tissue-equivalent material surrounding mandibular tray implants of titanium, vitallium, stainless steel, and Dacron/polyetherurethane. The absorbed dose was enhanced by 29% to 36% adjacent to the metallic trays; 1% dose enhancement was noted adjacent to the Dacron/polyetherurethane tray. We conclude that, when radiation therapy is necessary following mandibular reconstruction, homogeneity of dose is maintained and local soft-tissue reactions to excessive irradiation may be avoided by using a nonmetallic tray.

Biocompatible Materials↗
PubMed1976

Analysis of dose, dose-rate and treatment time in the production of injuries by radium treatment for cancer of the uterine cervix.

A retrospective study has been made of 15 patients who had developed severe complications to the bladder, rectum and ureters after radiation therapy for carcinoma of the cervix. Comprehensive dose distribution in the pelvis were calculated with computer assistance to visualize how the normal organs had been irradiated. The risk of normal tissue injury was analysed graphically with respect to the maximum radium dose, dose-rate and irradiation time. The two groups of data representing the injured and non-injured organs separate much better in a dose-rate versus dose plot than in a conventional Strandqvist type dose-time plot. This implies that in radium therapy, the dose-rate rather than the treatment time, is the important parameter in modifying the risk of normal tissue injury. Our results show a good separation of injured from non-injured cases only when the maximum values of dose and dose-rate were used. This suggests that clinically significant injury may develop from relatively small regions of high dose and dose-rate. Since the dose-rate varies from point to point in the pelvis (unlike treatment time), comprehensive determinations of dose-rate distributions are required in order to locate the sites of potential injuries.

Dose-Response Relationship, Radiation↗