Biomedical subjects

M T Gillin

Publications and source records attributed to M T Gillin.

At least 37 records · Page 2Linked to original sources

PubMed1989

Technical modifications in hyperfractionated total body irradiation for T-lymphocyte deplete bone marrow transplant.

The Medical College of Wisconsin implemented a major bone marrow transplant (BMT) program in July 1985. The type of transplants to be focused on were allogeneic T-lymphocyte deplete. Total body irradiation (TBI) was initially patterned after the Memorial method. Patients received total body irradiation in a sitting position at a dose rate of 20-25 cGy/minute with 50% attenuation lung blocks used both anterior/posterior and posterior/anterior. Electron boosting was utilized for the ribs beneath the lung blocks. Occasionally, lower extremity boosting was required because of the sitting position. A dose of 14 Gy was chosen since T-lymphocyte deplete bone marrow transplant data suggest the need for higher total doses to consistently obtain engraftment. This dose was given in 3 equal daily fractions over 3 days following conditioning chemotherapy. Six of 11 patients treated in this manner developed lethal pulmonary events. In response to the pulmonary toxicity, partial lung shielding was increased to 60% attenuation. In the next 107 patients receiving this program of total body irradiation there was a reduced incidence of fatal pulmonary events (10 cases of fatal idiopathic interstitial pneumonitis and 12 cases of fatal pulmonary infections) after a median follow-up of 9 months. This was an obvious improvement over the initial group. A significant level of hepato-renal toxicity was also observed with 14 Gy total body irradiation when no liver or kidney blocking was used. Of the first 20 patients treated, three cases of fatal veno-occlusive disease resulted. Subsequently, a 10% attenuation right sided liver block was added. Five of 98 patients treated with this block have developed fatal hepatic dysfunction, (median follow-up of 7.2 months). This incidence is not statistically different from the initial group but favors the use of the liver block. Some renal toxicity was also detected with the earlier regimen, especially in pediatric patients. Partial kidney blocking has been implemented to minimize this toxicity. Our current dose rate has been reduced to 8 cGy/minute in a further attempt to reduce organ toxicity. To date, this selective blocking has not adversely affected the excellent rate (96%) of first time engraftments.

Adolescent↗

PubMed1989

Electron beam port films.

Portal localization films are taken in order to assure the accurate placement of the treatment field relative to the patient anatomy. This is routinely done for photon fields and maybe for electron fields. This paper describes a technique which uses the bremsstrahlung component of an electron beam of energy 10 MeV and greater to expose a film to image a treatment port. These films provide verification of the placement of the electron field and document the treatment of a specific area.

Electrons↗

PubMed1989

Dose to the cardiac vascular and conduction systems in primary breast irradiation.

Using computerized tomography (CT) in which cardiac anatomy was defined, doses delivered to the cardiac compartments, vascular and conduction systems were assessed for various standard techniques of primary breast irradiation. Included in the analysis were 6 MV photon tangents (T) alone, or in conjunction with a separate internal mammary field (IMF). Beams evaluated in the IMF were 6 MV photons, 12 MeV electron beam, and mixed photon/electron beam; Cobalt 60 was also analyzed as an alternate photon beam. Treatment of the IMF with photons, either alone or in combination with electron beam, delivered doses ranging between 30 Gy to 50 Gy to all chambers of the heart, coronary arteries and branches of the conduction system. Complete sparing of the posterior cardiac structures and volume is accomplished with treatment plans using tangents alone or in combination with 12 MeV electron beam irradiation to the IMF. Sparing of the anterior wall of the left ventricle, Bundle of His and left anterior descending coronary artery is also achieved in treatment with tangents and 12 MeV electron beam IMF. Doses to this region with tangents alone ranged from 20 Gy to 45 Gy compared to 0 to 30 Gy with tangents and 12 MeV electron beam IMF. Clinical significance of these findings will be discussed.

Breast Neoplasms↗

PubMed1988

Head and neck tumors: dosimetric considerations of mixed-energy photon beam therapy.

The goal of sophisticated treatment planning in radiation therapy is to maximize dose to the tumor or target volume, while the integral dose is minimized, to reduce normal tissue morbidity. In the head and neck regions, the anatomic irregularities of individual patients and the critical structures that limit the administration of dose within the irradiated volumes often complicate the optimization of dosimetry. The availability of dual-energy accelerators that deliver beams of low- and high-energy photons allows the convenient administration of mixed-energy photon irradiation and facilitates the development of optimal treatment strategies for selected lesions. Highly lateralized carcinomas of the upper aerodigestive tract, in which sparing of contralateral cervicofascial tissue is desirable, are particularly well suited for this technique. Treatment plans that make use of irradiation with conventional single-energy beams and mixed-energy photon therapy are compared for representative lesions of the head and neck.

Carcinoma, Squamous Cell↗

PubMed1986

Dose distribution in total skin electron beam irradiation using the six-field technique.

Total skin low energy electron beam irradiation is used to treat superficially widespread skin lesions such as cutaneous T-cell lymphoma. Total skin irradiation involves delivering an adequate dose at a depth of 0.25 to 1.0 cm, while sparing underlying tissue. The dose distributions obtained when using a modified Stanford six-field technique depend upon the beam energy, the beam angle, the diameter and shape of the body part, and other variables. The dose distribution uniformity of six pairs of angulated electron beams has been studied as a function of beam energy, the gantry angle, +/- theta, above and below the horizontal and the diameter of a cylindrical polystyrene phantom. Depth doses and dose uniformity for single and multiple fields have been measured as a function of beam energy, phantom diameter and position.

Electrons↗

PubMed1985

Correlation of treatment volume with milligram-hours for intracavitary applications for carcinoma of the cervix.

Following the recommendations of the European Curietherapy Group, the three-dimensional dose distribution corresponding to various milligram-hour volumes has been analyzed according to its length, width, and height dimensions. Thus, it is possible to state the dimensions of a number of isodose surfaces for a dose prescription given in milligram-hours. Problems associated with the exact placement of the three-dimensional dose distribution in relation to the patient's anatomy are discussed.

Brachytherapy↗

PubMed1984

Single and double plane implants: a comparison of the Manchester System with the Paris System.

A comparison between the Manchester System and the Paris System of interstitial dosimetry has been made in the case of single and double plane implants. The rules of both systems are reviewed. A brief description of the Paris System is presented in an appendix. Dose distributions for two different examples are presented in two orthogonal planes. The Paris System uses considerably fewer sources than the Manchester System. It results in a larger volume of high dose than the Manchester System. The use of Iridium-192 sources strength and source length can be adjusted represents a significant advantage. The Paris System attempts to adapt the implant configuration to the clinical situation as the target thickness is used to define the source separation and the target length is used to define the source length. The differences in the dose definition are discussed.

Brachytherapy↗

PubMed1981