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Biomedical subjects

P Julin

Publications and source records attributed to P Julin.

At least 37 records · Page 2Linked to original sources
PubMed1988

Undiagnosed benign cementoblastoma in a patient with a 6-year pain condition. Report of a case.

Symptoms in the lower first molar developed in a 15-year-old girl. The problems started with tenderness during occlusion. The first radiographic examination revealed a radiopacity at the distal root, which was considered in the radiographic report to be a cementoma. Therapy commenced with occlusal adjustment, but this was followed 20 months later by endodontic therapy, which was undertaken because of the suspicion of partial pulpal necrosis with condensing osteitis. A painful condition developed and led first to apicoectomy and then to extraction 2 1/2 years after the start of the endodontic therapy. Light microscopic examination of adjacent hard tissue revealed signs of chronic inflammation on both occasions, and a diagnosis of diffuse sclerosing osteomyelitis was made. The pain was not relieved but remained at a tolerable level for 18 months. Then a reexamination of the first radiographs led to a strong suspicion of a benign cementoblastoma. A thorough third operation revealed a small piece of hard tissue in a lacuna of the lingual part of the mandible covered buccally by granulation tissue and inflammatory affected bone. The final histopathologic diagnosis was benign cementoblastoma combined with chronic inflammation.

Adolescent↗
PubMed1987

Rapid developing of Ektaspeed dental film by increase of temperature.

Three rapid developing solutions and one standard solution were tested for contrast and fog with Ektaspeed film at temperatures ranging from 15 degrees to 30 degrees C. Temperatures below 18 degrees C were found to give extremely long developing times, more than 3 minutes with rapid developers, and were not recommended. In the interval between 21 degrees C and 24 degrees C the standard developer needed 3.5-2.5 minutes to get optimum contrast. Two rapid developers needed 1.5 minutes and the fastest 1 minute to get satisfactory contrast throughout this temperature range. A further increase of the temperature gave only a marginal time saving with the rapid solutions and was not considered worthwhile. The relation between developing time and temperature for the rapid developers had a very steep gradient below 21 degrees C, while it levelled out at room temperature. For the standard developer the time/temperature function had a more even gradient from 7.5 minutes at 15 degrees C to 1.5 minutes at 27 degrees C, i.e. an average reduction of 0.5 minute per degree. Between 27 degrees C and 30 degrees C the gradient levelled out. The fog did not increase significantly until at 30 degrees C or at more than double the optimal developing time at room temperature. Recommendations of optimal developing time of Ektaspeed film at different temperatures are given for the four tested developing solutions.

Radiography, Dental↗
PubMed1986

Cysts of the nasopalatine duct.

Nasopalatine duct cysts in 70 patients were reexamined clinically and radiographically. 50 of them were also reexamined histopathologically. 20 specimens of normal duct tissue were likewise examined. More than half of the cysts showed clinical symptoms. The form on the radiograph was usually spherical or oval. Only 1 of 5 cysts was heart-shaped; 1 of 10 was unilateral. The mesiodistal width of the cysts ranged from 4-40 mm, with 75% from 6-12 mm. 3 of 4 showed pronounced radiolucency. Every 2nd cyst was completely surrounded by a thin radiopaque border. The histopathological investigation showed small cysts to be present in 1 of 4 clinically and radiographically normal nasopalatine ducts. More than 1 of 4 clinically and radiographically diagnosed cysts lacked histopathological characteristics of a cystic cavity. The type of epithelium in the cysts was independent of the vertical position in the duct.

Adolescent↗
PubMed1986

Optimal processing of Ektaspeed dental film.

Three rapid and two standard developing solutions have been tested. A jaw specimen and an aluminium step wedge were exposed on Kodak Ektaspeed film with a 60 kVp dental x-ray machine. The films were developed during varying times at 21 degrees C under controlled conditions. The image quality was tested with a densitometer as well as visually. The characteristic density curves were constructed and the relative speed, average density, fog and contrast were calculated for each test film. The time at which the contrast specified by the film manufacturer was reached, and beyond which the speed and contrast increased only marginally was regarded as the optimal developing time. With longer developing times no increase in image quality could be perceived visual by three trained observers. The optimal developing time at room temperature 21 degrees C, for the different solutions were found to be Kodak Dental 1:1 1.5 minutes Elfwing Rapid 1:3 1.0 minutes Scanfors Dental 1:2 1.5 minutes Kodak Dental 1:3 3.0 minutes Gevaert G 150 1:5 3.0 minutes The characteristic curves were identical for all developing solutions at the times recommended above and the total fog was below 0.20. However, the image quality was maintained and only an insignificant increase of fog was found even when those times were doubled.

Radiography, Dental↗
PubMed1985

Absorbed doses at varying tube voltage in lateral cephalography.

Absorbed doses in organs of special interest from lateral cephalography were measured by thermoluminescence dosimetry in a tissue equivalent phantom head. The radiographic examination was performed in a standardized manner by using a carefully collimated radiation field and a near-focus dodger. The actual tube voltages ranged from 63-127 kVp. The absorbed dose was described as a function of tube voltage. In all measurement sites the absorbed dose decreased with increasing tube voltage. This reduction was most obvious in the low tube voltage range. From the results a lowest recommendable tube voltage was given for the different measurement sites varying from approximately 75 kVp (thyroid region) to approximately 100 kVp (parotid region). A high tube voltage was found to be important for a low absorbed dose in different organs in lateral cephalography.

Bone Marrow↗
PubMed1984

Reduction of absorbed doses in radiography of the facial skeleton.

Radiation absorbed doses from radiography of the paranasal sinuses and the facial skeleton were measured with thermoluminescent dosimeters (TLD) on a phantom head using high-sensitivity screens in an Orbix stand. The entrance doses to the skin of the head ranged from 0.31 to 2.9 mGy per exposure. The absorbed dose from a full series of sinus exposures averaged 0.33 mGy for the oral mucous membrane, 0.33 mGy for the maxillary sinus mucous membrane, 0.11 mGy for the parotid gland, 0.15 mGy for the submandibular gland, 0.61 mGy for the eye lens, and 0.75 mGy for the thyroid gland region. A leaded soft collar adapted to the thyroid region reduced the thyroid doses by more than one order of magnitude, but also reduced the image field. The mean energy imparted from a full series of paranasal sinus projections was 4.8 mJ and from a total series of the facial skeleton, 7.9 mJ.

Facial Bones↗
PubMed1984

Radiation absorbed doses in cephalography.

Radiation absorbed doses to different organs in the head and neck region in lateral (LAT) and postero-anterior (PA) cephalography were investigated. The doses were measured by thermoluminescence dosimeters (TLD) on a tissue equivalent phantom head. Lanthanide screens in speed group 4 were used at 90 and 85 kVp. A near-focus aluminium dodger was used and the radiation beam was collimated strictly to the face. The maximum entrance dose from LAT was 0.25 mGy and 0.42 mGy from a PA exposure. The doses to the salivary glands ranged between 0.2 and 0.02 mGy at LAT and between 0.15 and 0.04 mGy at PA exposures. The average thyroid gland dose without any shielding was 0.11 mGy (LAT) and 0.06 mGy (PA). When a dodger was used the dose was reduced to 0.07 mGy (LAT). If the thyroid gland was shielded off, the dose was further reduced to 0.01 mGy and if the thyroid region was collimated out of the primary radiation field the dose was reduced to only 0.005 mGy.

Cephalometry↗
PubMed1983

Radiation shielding in dental radiography.

The protective effect in the thyroid region from different types of radiation shielding at intraoral radiography has been studied as well as the reduction of the absorbed dose to the sternal and the gonadal regions. The shielding tested were the different types of leaded aprons, of which three had an attached leaded collar and the other two were used in combination with separate soft leaded collars. Furthermore one of the soft leaded collars and an unflexible horizontal leaded shield were tested separately. Two dental x-ray machines of 60 and 65 kVp with rectangular and circular tube collimators were used. The exposure times corresponded to speed group E film. The absorbed doses were measured with two ionization chambers. No significant difference in the protective effect in the thyroid gland could be found between the different types of radiation shieldings. There was a dose reduction by approximately a factor of 2 to the thyroid region down to 0.08 mGy per full survey using parallelling technique, and below 0.001 mGy per single bitewing exposure. The shielding reduced the thyroid dose using bisecting-angle technique by a factor of 5 down to 0.15 mGy per full survey (20 exposures). In the sternal region the combinations of apron and collar reduced the absorbed dose from a full survey to below 2 microGy compared with 18 microGy (parallelling) and 31 microGy (bisecting-angle) without any shielding. With the horizontal leaded shield a reduction by a factor of 6 was obtained, but no significant sternal dose reduction could be detected from the soft collar alone. The gonadal dose could be reduced by a factor of 10 with the horizontal leaded shield, parallelling technique and circular collimator. Using leaded aprons the gonadal was approximately one per cent of the dose without any shielding, i.e. below 0.01 microGy per single intraoral exposure.

Humans↗
PubMed1982

Radiation absorbed doses at radiographic examination of third molars.

The radiation absorbed doses to critical organs, i.e. the thyroid and salivary glands and the gonadal region, were measured at radiographic examination of third molars. A tissue equivalent phantom was used together with ionization chamber detectors and TLDs. In the maxilla three, and in the mandible four different projections were used; also an extraoral lateral view. The greatest thyroid dose, 35 muGy, came from a mandibular disto-oblique projection with the circular tube collimator and Ultra-Speed film. the thyroid dose from an extraoral lateral view with high sensitivity screens was 3.7 muGy. The doses in different parts of the parotid gland from the disto-oblique mandibular projection with Ultra-Speed film ranged between 2.65 and 0.052 mGy. The corresponding doses in the submandibular gland were 1.74 mGy beneath the mandible and 0.458 mGy in the fovea. A rectangular tube collimator reduced the doses by approximately 50%. the Ekta-Speed film required approximately 40% lower exposure than the Ultra-Speed film. Without shielding the gonadal doses from a complete examination of four third molars were of the same order of magnitude as from a full survey with intraoral films, i.e. 3-7 muGy. A horizontal radiation shield reduced the thyroid doses by between 12 and 46% and the gonadal doses by between 50 and 95%. The reduction effect from the shield was relatively greater when using the larger aperture of the tube collimator. Combinations of leaded aprons and soft leaded collars reduced the thyroid doses by between 15 and 42% and the gonadal doses by two orders of magnitude.

Gonads↗
PubMed1981

Image distortion in rotational panoramic radiography. II. Vertical distances.

Films, exposed with rotational panoramic radiography, are generally considered inferior regarding the accuracy of measurements. Theoretic mathematical calculations, confirmed by an experimental test, have been performed in order to evaluate the reliability of measurements of distances that appear vertical in the image. It is demonstrated that, within certain limits, the panoramic film may be used for vertical measurements in clinical practice provided the patient has been properly positioned in the equipment during the exposure.

Mathematics↗