Fletcher-Suit colpostat has an internal structure to reduce dose to bladder and rectum. Some programs were developed to calculate dose at any point in water in three dimension around the colpostat containing Cs-137 tube, to find the shielding effect to dose by the internal structure, and to draw isodose cuties and iso-shielding effect cuties. Computer was an IBM compatible AT with EGA card and language was MS-Basic V6.0. Material, shape and geometry of the structure, tube and colpostat were considered in algorithm for calculation of dose. Dose rates per unit mg. Ra. eq. in water calculated by a program were stored in auxiliary memory devices and retrieved in another programs. Isodose curves on medial side shrieked. Dose distribution was not symmetric about a transverse axis bisecting the colpostat. Reduction of dose was more excessive on top side than on bottom. Iso-shielding effect cutie showed that the shielding effect was higher on top side than on bottom, and that there was shielding effect over almost all area of medial side. Such results were related to both shifted position of tribe in the colpostat and asymmetric distribution of active source in the tube. Maximum of shielding effect was 49% on top side and 44% on bottom side. The direction of iso-shielding effect curve was generally radial from the center of active source. In treatment planning using Fletcher-Suit colpostat, the internal structure should be considered to find precise doses to bladder and rectum, etc.
Axis, Cervical Vertebra ; Memory ; Rectum ; Urinary Bladder ; Water

This paper presents dose distributions in water around Fletcher-Suit colpostat containing 137Cs tube, and shielding effect of internal lead shield. Using ready packed film, author measured dose distribution in water around the colpostat containing cesium source. Nine sheets of films on one side of the colpostat are packed with acryl frames cut out so as to fill water, and irradiated in water by cesium source in the colpostat. Dose distributions on transverse plane and upper plane 0.5 cm from upper surface of the colpostat were measured. Shielding effect was greater in upper medial direction than in lower medial direction. And that was the greatest around 30degree from the axis of the colpostat on upper side and around 50degree on lower side. In the region 7 cm from the center of the colpostat, shielding efficiency was 0.23 to 0.35 on the lower 50degree and 0.26 to 0.42 on the upper 30degree, and decreased with increase of distance.
Axis, Cervical Vertebra ; Cesium ; Water

Several combinations of measuring devices and phantoms were studied to measure electron beams. Silicon PN junction diode was used to find the dependence of depth dose profile on field size on axis of electron beam Depths of 50, 80 and 90% doses increased with the field size for small fields. For some larger fields, they were nearly constant. The smallest of field sizes over which the parameters were constant was enlarged with increase of the energy of electron beams. Depth dose distributions on axis of electron beam of 10 x 10 cm2 field were studied with several combinations of measuring devices and phantoms. Cylindrical ion chamber could not be used for measurement of surface dose, and was not convenient for measurement of near surface region of 6 MeV electron. With some exceptions, parameters agreed well with those studied by different devices and phantoms. Surface dose in some energies showed 4% difference between maximum and minimum. For 18 MeV, depths of 80 and 90% doses were considerably shallower by film than by others. Parallel-plate ion chamber with polystyrene phamtom and silicon PN junction would be recommended for measurement of central axis depth dose of electron beams with considerably large field size. It is desirable not to use cylindrical ion chamber for the purpose of measurement of surface dose or near surface region for lower energy electron beam. It is questionable that film would be recommended for measurement of dose distribution of electron with high energy like as 18 MeV.
Axis, Cervical Vertebra ; Polystyrenes ; Silicones

Whole brain irradiation is one mode in the treatment of brain cancer and brain metastasis, but it might cause brain injury such as brain necrosis. It has been studied whether the dose distribution could be a cause of brain injury. The dose distribution in whole brain irradiated by Co-0 beam has been measured by means of calibrated TLD chips inserted in the brain of Humanoid phantom. The following results were obtained. 1. Dose distribution on each transverse section of the brain was uniform. 2. On the midsagital plane of the brain, the dose was highest in upper portion and lowest in lower portion, varying 8 from 104% to 90%. 3. When the radiation field includes free space of 2cm or more width out of the head, the dose distribution in the whole brain is almost independent of the field width. 4. It is important to determine adequate shielding area and to set shielding block exactly in repetition of treatment.
Brain Injuries ; Brain Neoplasms ; Brain* ; Head ; Necrosis ; Neoplasm Metastasis ; Radiotherapy*

PURPOSE: To investigate the levels of radiation exposure of an operator which may be influenced by the wearing an apron, type of procedure, duration of fluoroscopy and operator's skill during various interventional procedures MATERIALS AND METHODS: Radiation doses were measured both inside and outside the apron(0.5mm lead equivalent) of the operator by a film badge monitoring method and the duration of fluoroscopy was measured in 96 procedures prospectively. The procedures were 30 transcatheter arterial embolizations (TAE), 25 percutaneous transhepatic biliary drainages (PTBD), 16 stone removals (SR), 15 percutaneous needle aspirations (PCNA) and 10 percutaneous nephrostomies(PCN). To assess the difference of exposure by the operator's skill, the procedures of TAE and PTBD were done separately by groups of staffs and residents. RESULTS: Average protective effect of the apron was 72.8%. Average radiation exposure(unit:micro Sv/procedure) was 23.3 in PTBD by residents, 10.0 in PTBD by staffs, 10.0 in SR, 8.7 in TAE by residents, 7.3 in TAE by staffs, 9.0 in PCN and 6.0 in PCNA. Average radiation exposure of residents were 1.9 times greater than those of staffs. CONCLUSION: Radiation exposure was not proportionally related to the duration of fiuoroscopy, but influenced by wearing an apron, various types o[procedure and operator's skills.
Aspirations (Psychology) ; Film Dosimetry ; Fluoroscopy ; Needles ; Pregnenolone Carbonitrile ; Proliferating Cell Nuclear Antigen ; Prospective Studies

In brachytherapy of uterine cervical cancer using the high dose rate remote afterloading system, it is of prime importance to determine the position of the radiation sources and to estimate the irradiation time. However, calculation with manual method is so time consuming and laborious, that authors designed a software as an aid to intracavitary radiotherapy planning using the personal computer to obtain the precision of treatment without being too complicated for routine use. Optimal source arrangement in combination with dose rate at each specific points and irradiation time can be easily determined using this software in several minutes.
Brachytherapy* ; Microcomputers ; Radiotherapy ; Uterine Cervical Neoplasms*

In electron therapy, lead cutout or low-melting alloy block is used for shaping the field. Material for shaping electron field affects the output factor as well as the collimation system. The authors measured the output factors of electron beams for shaped fields from Clinac-18 using ionization chamber of Farmer type on polystyrene phantom. They analyzed the incident energy, collimation system and size of shaped field. For shaped field the variation of output factor for the field (A/P) has appearance of a smooth curve for all energy and all applicator collimator combination. The output factors for open field deviate from the curves for shaped fields. An output factor for a given field can be calculated by equivalent field method such as A/P method, if a combination of applicator and collimator is fixed.
Alloys ; Polystyrenes

The study was undertaken to assess the CT density of the antibiotics solution. CT scan of six antibioticssolution-streptomycin, chloramphenicol, Na-penicillin, ampicillin, kanamycin and cefamezine-in concentration ofabout 33% (approximatly single dose of intramuscular injection) was performed, using plastic syringes. Variousconcentrations of striptomycin, chloramphenicol and Na-panicillin were also examined for evaluation of relationbetween concentration and the CT density of the antibiotics. In addition, relationship between CT number andmathematically calculated effective atomic number and electron density of the antibiotics was evaluated. Theresults are as follows; 1. The CT densities of all antibiotics reveal high density (CT number 80–150) inconcentration of single intramuscular injection dose. 2. CT number of striptomycin, chloramphenicol andNa-penicillin gradually increased with increase of concentration of the antibiotics, producing linear proportionto concentration, effective atomic number and electron density of the antibiotics. 3. Therefore, density ofantibiotics should be included in differential diagnosis when high density on CT scan is observed.
Ampicillin ; Anti-Bacterial Agents ; Chloramphenicol ; Diagnosis, Differential ; Injections, Intramuscular ; Kanamycin ; Plastics ; Syringes ; Tomography, X-Ray Computed

High energy photon beam margin due to a less side scatter and the other things. But there still remains a penumbra where the dose changes rapidly in the region near the edge of a radiation beam, although it is short in width. It is suggested that the width of the penumbra depends on the source size, distance from source to diaphragm, source to skin distance, and depth in tissue. However, it is also supposed that the other factors influence the penumbra width. In this paper, we investigate changes of the physical penumbra widths according to various field sizes and depths, by using the three dimensional dosimetry system. As a result, we found that as field size and depth increase, the physical penumbra width also increases.
Diaphragm ; Skin

To obtain 7 MeV electron beam which is suitable for treatment of the chest wall after radical of modified radical mastectomy, the authors reduced the energy of electron beam by means by Lucite plate inserted in the beam. To determine the proper thickness of the Lucite plate necessary to reduce the energy of 9 MeV electron beam to 6 MeV, dosimetry was made by using a parallel plate ionization chamber in polystyrene phantom. Separation between two adjacent fields, 7 MeV for chest wall and 12 MeV for internal mammary region, was studied by means of film dosimetry in both polytyrene phantom and Humanoid phantom. The results were as follows. 1. The average energy of 9 MeV electron beam transmitted through the Lucite plate was reduced. Reduction was proportional to the thickness of the Lucite plate in the rate of 1.7 MeV/cm. 2. The proper thickness of the Lucite plate necessary to obtain 6 MeV electron beam from 9 MeV was 1.2 cm. 3. 7 MeV electron beam, 80% dose at 2cm depth, is adequate for treatment of the chest wall. 4. Proper separation between two adjacent electron fields, 7 MeV and 12 MeV, was 5mm on both flat surface and sloping surface to produce uniform dose distribution.
Film Dosimetry ; Mastectomy, Modified Radical ; Polymethyl Methacrylate ; Polystyrenes ; Thoracic Wall* ; Thorax*