[Personnel requirements of medical radiation physics in radiotherapy in comparison to the current guidelines "radiation protection in medicine" : Special consideration of intensity-modulated radiation therapy].

In 1994 and 1998 reports on staffing levels in medical radiation physics for radiation therapy were published by the "Deutsche Gesellschaft für Medizinische Physik" (DGMP, German Society for Medical Physics). Because of the technical and methodological progress, changes in recommended qualifications of staff and new governmental regulations, it was necessary to establish new staffing levels. The data were derived from a new survey in clinics.

[Staff requirements in medical radiation physics for diagnostic radiology in Germany: results of a questionnaire].

To get a general idea of the actual staffing situation in medical radiation physics, all active members of the German Society of Medical Physics (DGMP) were surveyed by the task force "staff requirements" ("Personalbedarf") of the DGMP in 1999. Of the 322 forms sent out, 173 could be evaluated. The staff requirements in medical radiation physics were calculated from the major elements of the radiology equipment and from the staff responsibilities as defined in the DGMP Reports 8 and 10, and compared with the actual number of staff members.

[Staffing levels in medical radiation physics in radiation therapy in Germany. Summary of a questionnaire].

To get a general idea of the actual staffing level situation in medical radiation physics in 1999 a survey was carried out by the task-group "Personalbedarf" of Deutsche Gesellschaft für Medizinische Physik (DGMP) among all DGMP-members who are active in this field. Main components for equipment and activities are defined in Report 8 and 10 of DGMP for staffing requirements in medical radiation physics. 322 forms were sent out, 173 of them have been evaluated.

[Staffing in medical radiation physics in Germany--summary of a questionnaire].

To obtain an overview of the actual staffing levels in Medical Radiation Physics, a survey was carried out in 1999 by the task-group "Staffing requirements" of the Deutsche Gesellschaft für Medizinische Physik (DGMP; German Society of Medical Physics) among all DGMP members active in this field. The main components for equipment and activities are defined as in Report 8 and 10 of the DGMP for staffing requirements in Medical Radiation Physics. The survey focused on these main components.

Physical and technical quality assurance in the CHARTWEL-Bronchus trial.

Background: On-site physical quality assurance (QA) was performed in the participating centers of the CHARTWEL-Bronchus trial to ensure that physical and technical treatment parameters correspond with the requirements of this trial.

Material And Methods: Questionnaires were sent to the clinics to obtain information on the equipment and in-house QA policies. In addition, two phantoms with drillings for an ionization chamber were shipped with detailed instructions for CT-based treatment planning of a fixed field (RW3 phantom) and a standardized isocentric 3-field technique (Rando humanoid phantom).

Short-term CT and MR changes in brain tumors following 125I interstitial irradiation.

Purpose: The study was undertaken to assess characteristic short-term CT and MR changes in brain tumors following 125I interstitial irradiation.

Method: Sixteen patients were included who had both CT and MR control examinations at regular intervals over a period of 18 months following treatment. Two groups were distinguished: low grade tumors (11 cases) and high grade malignancies (5 patients).

[Radiation exposure in abdominal radiography with digital luminescence radiography and conventional screen-film system: an experimental animal study].

Purpose: To determine and compare the minimum required radiation exposure for a.-p. abdominal radiographs with digital luminescence radiography (DLR) and a screen-film system (SFS) providing adequate image quality in clinical routine.

A study of dose reduction using digital luminescence radiography for lateral skull radiography.

For lateral skull radiography the minimum required radiation patient exposure to ensure adequate image quality was determined for digital luminescence radiography (DLR) in comparison with a screen-film system (speed class 200). Radiographs were produced with a grid technique on conventional X-ray equipment. A real prepared female head including a true fracture above the pars petrosa ossis temporalis was imaged.

[The personnel needs of health physics in radiotherapy].

Using a questionnaire, mean occupation time values for the different medical physics activities were derived in 1992; they formed the basis for recommendations of minimum physics staffing levels in radiotherapy. The recommended staffing levels were compared with the actual staffing levels and to other national and international recommendations.

The radiation exposure of the patient from stable-xenon computed tomography.

For stable-xenon computed tomography (CT), an X-ray examination for measurement of cerebral blood circulation in the brain, the radiation exposure of the patient was determined in order to estimate the risk of inducing cancer. Organ doses of brain, eyelenses, thyroid and gonads have been calculated using the measured air kerma free-in-air on the axis of rotation and organ-specific conversion factors calculated with the Monte Carlo method. Dose measurements with TLD-100 rods using a humanoid Alderson phantom were carried out for verification of the calculated organ doses.

[Computer-assisted dosimetry system for the monitor calibration of accelerators].

Purpose: A computerized dosimetry system for calibration of the dose monitor of a medical accelerator was developed with the aim of saving time and reducing errors during measurement and analysis of measured data.

Method: The PC-based part of the programme system controls measurements with dosimeters of type Dosimentor using an interface IF4. After transmission of the measured data to an UNIX-network the other part of the programme system serves as a tool for analysis.

[The determination of the ovarian dosage in defecography on a digital C-arm unit].

When using defaecography as a radiological tool for diagnosing the anorectal function in female patients, the ovaries are inevitably directly exposed. With the aim of minimising the ovarian dose applied both the area-dose product and the surface dose above the ovaries were measured during investigations of female patients with a digital C-arm unit. These values were converted into ovarian doses using tissue-air ratios.

[A mathematical description of the relative dosage distributions of stereotactic collimator tubes in 6-MV photon radiation].

The relative dose distributions of small circular fields for 6 MV photons may be calculated using a simple mathematical model. This model has been developed for stereotactic collimators with cylindrical cross section and diameters between 5 mm and 30 mm. The model consists of the description of depth dose curves and off-axis dose distributions.

[Monte Carlo calculations and TLD measurements to determine the two-dimensional dosage distribution of 125-iodine seed, Model 6702].

The angular and radial dose distribution around a type 6702 125-Iodine-seed was measured in water and air using thermoluminescence dosimetry. The radial distribution could be confirmed using Monte Carlo simulation techniques. The simulation produced enough data to allow the derivation of a new analytical function describing the radial dose distribution.

[Uncertainties in the localization of radiation sources in brachytherapy].

While investigating ways to solve the problem of locating radiation sources applied in brachytherapy a device was constructed which enables a precise assessment of their or their applicators' position from two only roughly positioned orthogonal radiographs. The overall accuracy (including exposure and evaluation) achieved is +/- 1 mm. The constructional elements and the evaluation algorithm are described and the influence of the location uncertainty on the uncertainty of the dose applied are discussed.

[A simple device for positioning and fixing the head in radiotherapy of brain tumors in frontal and lateral position].

In radiotherapy of cerebral tumors in the occipital, central, and parietal area it can be favourable to fix the patient's head in frontal or lateral position. It is true that this problem can be solved by manufacturing individual face masks of PVC with the vacuum deep-drawing method, but this method is very time- and cost-consuming. The present study suggests a simplified method using the thermoplastic polyester "Orfit".

Plastic material used to optimize radiotherapy of head and neck tumors and the mammary carcinoma.

In order to improve head and neck tumor therapy, face masks were developed. The physical and mechanical properties of 11 apparently suitable materials were tested using a phantom. According to our studies "HEXCELITE" (supplied by Medimex, Hamburg, F.

[Systematic research on the dose distribution in mantle field irradiation with Co60 gamma radiation in the Alderson phantom].

A mantle field is localized according to the patient's data in an inhomogenous Alderson phantom. After having established the irradiation scheme, the dose distributions measured in the Alderson phantom are compared with those measured and calculated in an homogenous water phantom. The possible side effects of this irradiation technique can be assessed on the basis of the radiation exposure of heart, lung and spinal marrow.

[Chest wall moulages for radiotherapy of resected breast cancer with fast electrons: comparative tests of different materials].

Irradiation of the thoracic wall with high-speed electrons is one of the standard methods of prophylaxis and therapy of local recurrences and cutaneous metastases of an operated mammary carcinoma. The surface dose, however, is only 85% of the maximum dose, due to the depth dose curve of the electron beams with the preponderantly applied energy of 7MeV. This is a poor value, since most of all recurrences appear near to the surface and so the risk of giving an insufficient dose is involved.

[Face masks for radiotherapy of head and neck tumors: comparative tests of different materials].

A most precise immobilisation of the patient's head is indispensable in order to reach a high degree of exactness and reproducibility in radiotherapy of malignant head and neck tumors. Face masks made of different synthetic materials have proved to be a simple and economical solution for this problem. Based on our own experiences with "Baycast Longuettes" (manufacturing firm: Johnson & Johnson, Düsseldorf), eleven substances have been tested in the phantom (compound of plaster and synthetic resin, thermoplast, polyurethane foam, compounds of cotton and synthetic resin, and fibre glass compounds).

[Calculation of the dose distribution for ultrahard X-ray bremsstrahlung].

The dose distribution of the 42 MV X-ray bremsstrahlung of the betatron is represented by reference dose, depth dose and transverse dose. The method used to determine the parameters of a system of functions to approximate reference dose and depth dose is described and the coefficient schemes of the functions are indicated. The standardized equivalent field surface and the opening ratio of the useful radiation stop of the betatron serve as variables for the approximation.