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Biomedical subjects

R Walstam

Publications and source records attributed to R Walstam.

At least 19 recordsLinked to original sources
PubMed1995

Therapeutic radiation physics. A review of developments in Sweden.

Therapeutic radiology was initially based purely on clinical experience. Radiation physics was introduced in Sweden when Rolf M. Sievert started the "Radiumhemmet Physics Laboratory" in 1920. Dosimetry standards, in vivo dosimetry, brachyradium techniques, teleradium therapy and radiation protection were areas for development. After world war II there has been a continuous expansion of the profession due to the introduction of high energy accelerators for photon and electron therapy and artificial radionuclides. Hospital physicists are responsible for the performance of advanced equipment, design and use of beaming shaping devices, and computer systems for treatment planning and verification. Swedish physicists have been engaged in the international organizations for radiation dosimetry (ICRU) and radiation protection (ICRP), in activities by IAEA, WHO, and UNSCEAR. The international cooperation in hospital physics and radiation protection has been initiated and promoted by Swedish physicists.

History, 19th Century↗
PubMed1977

Electron therapy of intraorbital tumors.

The authors describe a modification of a previously reported method of treating intraorbital tumors using multiple electron beams. An adjustable metal shield is inserted in the electron tube to protect the lens. The three-dimensional dose distribution was determined by film measurements and the film density measured with an RFA-1 densitometer on line with a computer. The density values were stored in a three-dimensional matrix. Different planes in the matrix can be selected for isodose plotting.

Electrons↗
PubMed1977

[Radiation-physical conditions concerning irradiation by means of remote afterloading (author's transl)].

Afterloading techniques, proposed as early as 1903, came into practical use only during the last two decades. Remote afterloading techniques were introduced clinically when suitable sealed gamma sources became available and reliable equipment were designed, transferring the radiation sources between a shielding container and suitably designed irradiators in the patient. The technique can be used with low or high dose-rate and offers several advantages, such as complete elimination of all radiation protection problems, optimization of the treatment technique - through several means - and possibly increased treatment capacity. Two applications of a particularly flexible system are illustrated. Requirements for the development, advantages with today's technique and possibilities for future development are discussed.

Female↗
PubMed1976

Radiation therapy of nasopharyngeal carcinoma in East Africa.

Results of irradiation, 1 to 3 years after treatment, are presented in 64 cases of nasopharyngeal carcinoma in East Africans. Two types of anatomic point indices are presented. Both correlate well with the results. Prophylactic irradiation of the mediastinum and both axillae was not followed by any evident improvement of the results.

Adolescent↗
PubMed1975

[Possibilities of dose distribution in the afterloading technic].

Remote (controlled) afterloading installations, offer the possibility to improve the dose distributions of the different applicators, since this apparatus permits the employment of artificial radionuclides with a high specific activity and with low energy of gamma rays. It is therefore possible to incorporate effective shielding into the applicators. The possible individual fitting of the dose distribution, however, demands considerable clinical effort, as the extension of the tumor in question has to be ascertained with sufficient accuracy. Otherwise, underdosage to tumor cells may happen within the shielded area. Most afterloading techniques are using stiff applicators and geometrical fixation within patients; configuration and position of the radiation sources in the patient therefore remain unchanged during the whole irradiation. Thus, it becomes possible to adapt additional external irradiation more exactly than before to the intracavitary dose distribution.

Female↗
PubMed1975

[Criteria for an optimal isotope in gynecologic radiotherapy].

With regard to the evident disadvantages of radium, nowadays an artificial radiation source always should be considered, since it may be much more favorable for any intracavity application. The most usual ones are Cs-137, Co-60 and Ir-192. Each of these isotopes has its advantages and disadvantages; therefore the choice of the isotope must take into account the criteria and requirements for each intracavitary radiation technique.

Cesium Radioisotopes↗