Dosimetry is the measuring of ionizing radiation at a place or in an individual. Its is a tool meant to give approximate amounts or effective dose occurring due to exposure over a given time.
Dose Estimates from Diagnostic Imaging Procedures
Fetal dose calculations
To calculate the fetal dose radiation FetDose V4 software from radiographic and CT examinations are mostly, it estimates fetal radiation doses. The fetal can absorb dose from a chain of radiographic sessions attended by the mother. To calculate the surface dose for any radiograph, the following formulae apply.
Df=∑i=1nNUDd, ESD, i×ESDradio, i×SFi
ESDrad=[(FSDQAFSDEX)×(kVpEXkVpQA)]2×output×mA
Df=∑i=1nDAPi×NUDd, DAP, i×SFi
The fetal dose CT session is calculated using the equation.
Df = (NUDV × CTDIsoft tissue × [mAs / 100]) / Pitch
Pediatric dose issues
The biological effect of radiations in the fetus is categorized into two: deterministic and stochastic. When the radiation-caused effects occur in exposure to emissions exceeding a minimum threshold, deterministic effects arise. These include skin injury, cataracts, alopecia, or sterility. Other effects occurring due to dose given are stochastic. Radiation safety standard has been developed to control potentially dangerous radiation; the safety standard has been set to 1mSv, which is low and poses a minimum and negligible risk of fetal damage. Depending on the level of exposure, the miscarriage and neonatal deaths may occur, growth restrictions, and malformations.
Risk estimates
The risk estimated for fetal development is high due to the large number of pregnant mothers exposed to varying degrees of exposure. Depending on the levels of exposure, different health effects occur due to radiation doses. Radiations reaching mothers’ blood are transferred to the fetus’s bloodstream. The amounts of these radiations and the stage of fetal growth, together with the radiation’s properties, cause a range of health conditions for the fetus.
Points of Concern During Therapy
Pacemakers and the radiation field
Using radiotherapy in regions close to implanted pacemaker makes it malfunction or cause it to fail. The failure is attributed to ionizing effect and electromagnetic interference. The radiations destroy the electromagnetic components of the pacemaker and interfere with its memory. Furthermore, it loads the insulator with many electron-holes, which accumulates charges on it.
Dose estimates near prosthetics
The dose estimate differs depending on the region where the prosthesis is situated; care should be taken to avoid exposing it to radiation. Radiation therapy doses around the pelvic area should be 65Gy or lower. A 25% increment on a healthy bone near the prosthesis may not cause a surge in morbidity. Other findings recommend that 78Gy be the maximum level for exposure in a region near prosthesis beyond which morbidity may occur.
Large patients and skin reaction
The area to be exposed to radiation need to be handled with care. The skin should be washed gently using lukewarm water and little soap and then be dried. Lotion, ointment, makeups, and perfumed products are not used. The named products interfere with radiations and the treatment or may cause irritation after the treatment. There is more risk for developing skin cancer if care is not taken, exposing the treated area to the sun during or after treatment.
TPS model accuracy issues
TPS model accuracy errors require a medical physicist to be very vigilant when generating the beams and setting them to avoid inaccurately calculated dose. TPS issues occur when the system generates the beam quality different from its expected quality; the variance causes more or less radiation exposure to the patient leading to severe complications.
In conclusion, it is critical to understand the working of the radiation and dangers it poses to patients. Care should be taken to ensure the treatment planning system is working accurately. The medical physicist should be extremely vigilant to notice slight changes it the workings of the system. Radiations can pose adverse effects of fetal development, health cells, and prosthesis, confirming that TPS should be regularly checked for proper functioning.